WO2013051824A1 - Apparatus and method for controlling uplink transmission power in a wireless communication system - Google Patents

Apparatus and method for controlling uplink transmission power in a wireless communication system Download PDF

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Publication number
WO2013051824A1
WO2013051824A1 PCT/KR2012/007902 KR2012007902W WO2013051824A1 WO 2013051824 A1 WO2013051824 A1 WO 2013051824A1 KR 2012007902 W KR2012007902 W KR 2012007902W WO 2013051824 A1 WO2013051824 A1 WO 2013051824A1
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Prior art keywords
transmission
uplink
reference signal
path loss
terminal
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PCT/KR2012/007902
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French (fr)
Korean (ko)
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김종남
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주식회사 팬택
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/06—TPC algorithms
    • H04W52/14—Separate analysis of uplink or downlink
    • H04W52/146—Uplink power control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/24—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters
    • H04W52/242—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters taking into account path loss
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/022—Site diversity; Macro-diversity
    • H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/26—TPC being performed according to specific parameters using transmission rate or quality of service QoS [Quality of Service]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/38—TPC being performed in particular situations
    • H04W52/40—TPC being performed in particular situations during macro-diversity or soft handoff

Definitions

  • the present invention relates to wireless communication, and more particularly, to an apparatus and method for controlling uplink transmission power in a wireless communication system.
  • Multi-cell coordination is also referred to as cooperative multiple point transmission and reception (CoMP).
  • CoMP includes a beam avoidance technique in which neighboring cells cooperate to mitigate interference to a user at a cell boundary, and a joint transmission technique in which neighboring cells cooperate to transmit the same data.
  • Next-generation wireless communication systems such as Institute of Electrical and Electronics Engineers (IEEE) 802.16m or 3rd Generation Partnership Project (3GPP) long term evolution (LTE) -Advanced, are located at cell boundaries and are subject to severe interference from adjacent cells.
  • IEEE Institute of Electrical and Electronics Engineers
  • 3GPP 3rd Generation Partnership Project
  • LTE long term evolution
  • CoMP can be considered.
  • CoMP Co-power remote radio heads
  • a criterion for determining the uplink transmission power has not yet been determined.
  • An object of the present invention is to provide an apparatus and method for controlling uplink transmission power in a wireless communication system.
  • Another object of the present invention is to provide an apparatus and method for operating in a muting mode in a PL measurement section.
  • Another object of the present invention is to provide an apparatus and method for obtaining an uplink path loss value using a reference signal received in a PL measurement section.
  • Another technical problem of the present invention is to provide an apparatus and method for calculating an uplink path loss value for each transmit / receive point in a cooperative multipoint scheme in which a plurality of transmit / receive points communicate with a terminal.
  • a control method of uplink transmission power for a terminal performed by a terminal.
  • the method includes the steps of calculating, by the terminal, an uplink path loss value in a designated PL measurement interval to measure an uplink pathloss (PL) value, and calculating an uplink transmission power based on the uplink path loss value. And transmitting an uplink signal according to the uplink transmission power.
  • the PL measurement interval includes a plurality of subframes, the PL measurement interval includes non-transmission timing at which a sub-transmission point operates in a muting mode, wherein the sub-transmission point is a sub-transmission point for a cell specific reference signal. This mode is set to zero-power.
  • a method of controlling uplink transmission power for a terminal performed by a remote radio head may include operating in a muting mode at a non-transmission timing included in a PL measurement interval used for measuring an uplink pathloss (PL) value by the terminal, in the PL measurement interval, in addition to the non-transmission timing. Transmitting a cell-specific reference signal to the terminal at a time point; and receiving, from the terminal, an uplink signal transmitted with uplink transmission power based on an uplink path loss value calculated in the PL measurement interval. .
  • PL pathloss
  • the path loss value of each uplink receiving point can be independently measured, and the uplink transmission power is estimated by inferring the uplink path loss values of the entire uplink receiving points. Can be controlled.
  • estimating uplink path loss using CRS increases the reliability of the measurement compared to using other reference signals such as CSI-RS, and also prevents the decrease in data transmission efficiency due to the overshoot of reference signal transmission. have.
  • FIG. 1 is a block diagram showing a wireless communication system to which the present invention is applied.
  • FIGS. 2 and 3 schematically show the structure of a radio frame to which the present invention is applied.
  • FIG. 4 is a flowchart illustrating a method of controlling uplink transmission power for a terminal according to an embodiment of the present invention.
  • FIG. 5 is a diagram illustrating a non-transmission timing in a muting period and an offset according to an embodiment of the present invention.
  • FIG. 6 is a diagram illustrating non-transmission timing in a PL measurement section according to an embodiment of the present invention.
  • FIG. 7 is a flowchart illustrating an operation of measuring, by the terminal, an uplink power loss value using a PL measurement interval according to an embodiment of the present invention.
  • FIG. 8 is a diagram illustrating a non-transmission timing in a muting period according to an embodiment of the present invention.
  • FIG. 9 is a flowchart illustrating an operation of measuring an uplink power loss value by a terminal according to another embodiment of the present invention.
  • FIG. 10 is a flowchart illustrating a method of controlling a transmission of a reference signal in a PL measurement section by a sub transceiver according to an example of the present invention.
  • 11 is an example of a scenario of controlling uplink transmission power according to the present invention.
  • FIG 13 is another example of a scenario of controlling uplink transmission power according to the present invention.
  • FIG. 14 is a block diagram illustrating a terminal and a transmission and reception point according to an embodiment of the present invention.
  • the present specification describes a communication network, and the work performed in the communication network is performed in the process of controlling the network and transmitting data in a system (for example, a base station) that manages the communication network, or a terminal linked to the network. Work can be done in a system (for example, a base station) that manages the communication network, or a terminal linked to the network. Work can be done in a system (for example, a base station) that manages the communication network, or a terminal linked to the network. Work can be done in a system (for example, a base station) that manages the communication network, or a terminal linked to the network. Work can be done in a system (for example, a base station) that manages the communication network, or a terminal linked to the network. Work can be done in a system (for example, a base station) that manages the communication network, or a terminal linked to the network. Work can be done in a system (for example, a base station) that manages the communication network, or a terminal linked to
  • control channel may be interpreted to mean transmitting control information through a specific channel.
  • the control channel may be, for example, a physical downlink control channel (PDCCH) or a physical uplink control channel (PUCCH).
  • PDCH physical downlink control channel
  • PUCCH physical uplink control channel
  • FIG. 1 is a block diagram showing a wireless communication system to which the present invention is applied.
  • the wireless communication system 10 is widely deployed to provide various communication services such as voice and packet data.
  • the wireless communication system 10 includes at least one base station (BS) 11.
  • Each base station 11 provides a communication service for a particular geographic area or frequency area (generally called a cell) 15a, 15b, 15c.
  • Cells 15a, 15b, and 15c may in turn be divided into a number of regions (called sectors).
  • the user equipment (UE) 12 may be fixed or mobile, and may include a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, and a PDA. (personal digital assistant), wireless modem (wireless modem), a handheld device (handheld device) may be called other terms.
  • the base station 11 generally refers to a station that communicates with the terminal 12, and includes an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, an femto eNB, and a home. It may be referred to by other terms such as a base station (HeNB), a relay, a remote radio head (RRH), and the like.
  • eNB evolved-NodeB
  • BTS base transceiver system
  • HeNB base station
  • RRH remote radio head
  • Cells 15a, 15b, and 15c should be interpreted in a comprehensive sense indicating some areas covered by the base station 11, and encompass all of the various coverage areas such as megacells, macrocells, microcells, picocells, and femtocells. to be.
  • downlink refers to a communication or communication path from the base station 11 to the terminal 12
  • uplink refers to a communication or communication path from the terminal 12 to the base station 11.
  • the transmitter may be part of the base station 11 and the receiver may be part of the terminal 12.
  • the transmitter may be part of the terminal 12 and the receiver may be part of the base station 11.
  • CDMA Code Division Multiple Access
  • TDMA Time Division Multiple Access
  • FDMA Frequency Division Multiple Access
  • OFDMA Orthogonal Frequency Division Multiple Access
  • SC-FDMA Single Carrier-FDMA
  • OFDM-FDMA OFDM-FDMA
  • OFDM-FDMA OFDM-FDMA
  • OFDM-TDMA OFDM-FDMA
  • the uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme transmitted using different times or a frequency division duplex (FDD) scheme transmitted using different frequencies.
  • TDD time division duplex
  • FDD frequency division duplex
  • the wireless communication system 10 may be a Coordinated Multi Point (CoMP) system.
  • the CoMP system refers to a communication system supporting CoMP or a communication system to which CoMP is applied.
  • CoMP is a technique for adjusting or combining signals transmitted or received by multi transmission / reception (Tx / Rx) points.
  • CoMP can increase data rates and provide high quality and high throughput.
  • the transmission / reception point may be defined as a component carrier or a cell or a base station (macro base station, pico base station, femto base station, etc.), or a remote radio head (RRH).
  • the transmission / reception point may be defined as a set of antenna ports.
  • the transceiver may transmit information about the set of antenna ports to the terminal through radio resource control (RRC) signaling. Therefore, a plurality of transmission and reception points in one cell may be defined as a set of antenna ports. The intersection between the set of antenna ports is always empty.
  • RRC radio resource control
  • the base station 11 of the cell 15a, the base station 11 of the cell 15b and the base station 11 of the cell 15c may configure multiple transmission / reception points.
  • the multiple transmit / receive points may be base stations of a macro cell forming a homogeneous network.
  • the multiple transmit / receive points may also be base stations of macro cells and base stations of pico cells within macro cells, forming a heterogeneous network.
  • the multiple transmission / reception points may be a base station of the macro cell and a remote radio unit (RRU) in the macro cell.
  • the multiple transmission / reception points may be RRHs belonging to the base station of the macro cell and RRHs belonging to the base station of the heterogeneous cell (e.g. pico cell) in the macro cell.
  • the CoMP system may selectively apply CoMP.
  • a mode in which a CoMP system performs communication using CoMP is called a CoMP mode, and a mode other than the CoMP system is called a normal mode.
  • the CoMP system may operate in CoMP mode.
  • the CoMP system may operate in a normal mode.
  • the terminal 12 may be a CoMP terminal.
  • the CoMP terminal is a component of the CoMP system and performs communication with a CoMP cooperating set. Like the CoMP system, the CoMP terminal may operate in the CoMP mode or in the normal mode.
  • the CoMP cooperative set is a set of transmit / receive points that directly or indirectly participate in data transmission on a time-frequency resource for a CoMP terminal.
  • the base station 11 of the cell 15a, the base station 11 of the cell 15b, and the base station 11 of the cell 15c may form a CoMP cooperative set.
  • the transmit and receive points do not necessarily have to provide the same coverage.
  • base station 11 of cell 15a may be a base station providing a macro cell
  • base station 11 of cell 15b may be an RRH.
  • Participating directly in data transmission or reception means that the transmitting and receiving points transmit downlink data to the CoMP terminal or receive uplink data from the CoMP terminal.
  • Indirect participation in data transmission or reception means that the transmit / receive points do not transmit downlink data to the CoMP terminal or receive uplink data from the CoMP terminal, but contribute to making a decision about user scheduling / beamforming. .
  • the CoMP terminal may simultaneously receive signals from the CoMP cooperative set or transmit signals simultaneously to the CoMP cooperative set. At this time, the CoMP system minimizes the interference effect between the CoMP cooperation sets in consideration of the channel environment of each cell constituting the CoMP cooperation set.
  • a channel environment is formed between the reception point and the CoMP terminal.
  • the channel environment is a set of parameters that affect scheduling for a CoMP terminal, such as a frequency bandwidth allocated to the CoMP terminal and a downlink pathloss (PL).
  • the channel environment is formed individually for each receiving point. This means that the channel environment may be different for each receiving point. If the channel environment is different for each receiving point, the CoMP terminal should set uplink transmission power differently for each receiving point. Therefore, the CoMP terminal needs to know how the channel environment is different for each receiving point.
  • the first scenario is an intra-site CoMP scenario in which a plurality of cells exist around one base station.
  • the second scenario is a high-power CoMP scenario in which a plurality of high-power RRHs exist around one macro cell.
  • the third scenario is a CoMP scenario in which a low-power RRH exists around one macro cell but the physical cell ID of the RRH and the physical cell ID of the macro cell are not the same.
  • the fourth scenario is a CoMP scenario in which a low-power RRH exists around one macro cell, but the physical cell ID of the RRH and the physical cell ID of the macro cell are the same. Therefore, in the fourth scenario, the transmission pattern of the reference signal determined by the cell ID also matches.
  • the transmission and reception point to which the present invention is applied may include a base station, a cell, or an RRH. That is, the base station or the RRH may be a transmission / reception point. Meanwhile, the plurality of base stations may be multiple transmission / reception points, and the plurality of RRHs may be multiple transmission / reception points. Of course, the operation of all base stations or RRH described in the present invention can be equally applied to other types of transmission and reception points.
  • the layers of the radio interface protocol between the terminal and the base station are based on the lower three layers of the Open System Interconnection (OSI) model, which is well known in the communication system. It may be divided into a second layer L2 and a third layer L3. Among them, the physical layer belonging to the first layer provides an information transfer service using a physical channel.
  • OSI Open System Interconnection
  • the PDCCH includes a resource allocation and transmission format of a downlink shared channel (DL-SCH), resource allocation information of an uplink shared channel (UL-SCH), and a physical downlink shared channel.
  • Resource allocation of a higher layer control message such as a random access response transmitted on a PDSCH, a set of transmission power control (TPC) commands for individual terminals in an arbitrary terminal group, and the like.
  • TPC transmission power control
  • a plurality of PDCCHs may be transmitted in the control region, and the terminal may monitor the plurality of PDCCHs.
  • DCI downlink control information
  • the DCI may include an uplink or downlink resource allocation field, an uplink transmission power control command field, a control field for paging, a control field for indicating a random access response (RA response), and the like.
  • DCI has different uses according to its format, and fields defined in DCI are also different.
  • Table 1 shows DCIs according to various formats.
  • Table 1 DCI format Explanation 0 Used for scheduling of PUSCH (Uplink Grant) One Used for scheduling one PDSCH codeword in one cell 1A Used for simple scheduling of one PDSCH codeword in one cell and random access procedure initiated by PDCCH command 1B Used for simple scheduling of one PDSCH codeword in one cell using precoding information 1C Used for brief scheduling of one PDSCH codeword and notification of MCCH change 1D Used for simple scheduling of one PDSCH codeword in one cell containing precoding and power offset information 2 Used for PDSCH scheduling for UE configured in spatial multiplexing mode 2A Used for PDSCH scheduling of UE configured in long delay CDD mode 2B Used in transmission mode 8 (double layer transmission) 2C Used in transmission mode 9 (multi-layer transmission) 3 Used to transmit TPC commands for PUCCH and PUSCH with power adjustment of 2 bits 3A Used to transmit TPC commands for PUCCH and PUSCH with single bit power adjustment 4 Used for scheduling of PUSCH (Uplink Grant). In particular, it is used for PUSCH scheduling for a
  • DCI format 0 is uplink scheduling information, format 1 for scheduling one PDSCH codeword, format 1A for compact scheduling of one PDSCH codeword, and very simple of DL-SCH.
  • Format 1C for scheduling format 2 for PDSCH scheduling in closed-loop spatial multiplexing mode, format 2A for PDSCH scheduling in open-loop spatial multiplexing mode, and uplink channel Formats 3 and 3A for transmission of a transmission power control (TPC) command.
  • TPC transmission power control
  • Each field of the DCI is sequentially mapped to n information bits a 0 to a n-1 . For example, if DCI is mapped to information bits of a total of 44 bits in length, each DCI field is sequentially mapped to a 0 to a 43 .
  • DCI formats 0, 1A, 3, and 3A may all have the same payload size.
  • DCI format 0 may be called an uplink grant.
  • FIGS. 2 and 3 schematically show the structure of a radio frame to which the present invention is applied.
  • a radio frame includes 10 subframes.
  • One subframe includes two slots.
  • the time (length) of transmitting one subframe is called a transmission time interval (TTI).
  • TTI transmission time interval
  • one subframe may have a length of 1 ms
  • one slot may have a length of 0.5 ms.
  • One slot may include a plurality of symbols in the time domain.
  • the symbol in a wireless system using orthogonal frequency division multiple access (OFDMA) in downlink (DL), the symbol may be an orthogonal frequency division multiplexing (OFDM) symbol.
  • OFDM orthogonal frequency division multiplexing
  • the representation of the symbol period in the time domain is not limited by the multiple access scheme or the name.
  • the plurality of symbols in the time domain may be a Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbol, a symbol interval, or the like in addition to the OFDM symbol.
  • SC-FDMA Single Carrier-Frequency Division Multiple Access
  • the number of OFDM symbols included in one slot may vary depending on the length of a cyclic prefix (CP). For example, in case of a normal CP, one slot may include 7 OFDM symbols, and in case of an extended CP, one slot may include 6 OFDM symbols.
  • CP cyclic prefix
  • One slot includes a plurality of subcarriers in the frequency domain and seven OFDM symbols in the time domain.
  • a resource block (RB) is a resource allocation unit. If a resource block includes 12 subcarriers in the frequency domain, one resource block may include 7 ⁇ 12 resource elements (REs).
  • the resource element represents the smallest frequency-time unit to which the modulation symbol of the data channel or the modulation symbol of the control channel is mapped. If there are M subcarriers on one OFDM symbol, and one slot includes N OFDM symbols, one slot includes MxN resource elements.
  • a wireless communication system it is necessary to estimate an uplink channel or a downlink channel for data transmission / reception, system synchronization acquisition, channel information feedback, and the like.
  • the process of restoring a transmission signal by compensating for distortion of a signal caused by a sudden change in channel environment is called channel estimation.
  • channel estimation it is necessary to measure the channel state (channel state) for the cell to which the terminal belongs or other cells.
  • a reference signal (RS) that is known to the UE and the transceiver is mutually used for channel estimation or channel state measurement.
  • the channel estimate estimated using the reference signal p Is Depends on the value, so to get an accurate estimate of You need to converge to zero.
  • the channel can be estimated by minimizing the effects of
  • the reference signal may be allocated to all subcarriers or may be allocated between data subcarriers for transmitting data.
  • a signal of a specific transmission timing is composed of only a reference signal such as a preamble in order to obtain a gain of channel estimation performance. In this case, the data transfer amount is relatively reduced.
  • the amount of data transmission can be increased.
  • the downlink reference signal includes a cell-specific RS (CRS), an MBSFN reference signal, a UE-specific RS, a positioning reference signal (PRS), and channel state information (CSI). And a reference signal (CSI-RS).
  • CRS cell-specific RS
  • MBSFN reference signal MBSFN reference signal
  • PRS positioning reference signal
  • CSI-RS channel state information
  • resource elements used for reference signals of one antenna are not used for reference signals of another antenna. This is to avoid interference between antennas. For example, only one reference signal may be transmitted per antenna.
  • the CRS is a reference signal transmitted to all terminals in a cell and used for channel estimation.
  • the CRS may be transmitted in all downlink subframes in a cell supporting PDSCH transmission.
  • the UE specific reference signal is a reference signal received by a specific terminal or a specific terminal group in a cell, and is mainly used for data demodulation of a specific terminal or a specific terminal group, and thus may be called a demodulation RS (DMRS).
  • DMRS demodulation RS
  • the MBSFN reference signal is a reference signal for providing a multimedia broadcast multicast service (MBMS) and may be transmitted in a subframe allocated for MBSFN transmission.
  • the MBSFN reference signal may be defined only in the extended CP structure.
  • the PRS may be used for location measurement of the terminal.
  • the PRS may be transmitted only through resource blocks in a downlink subframe allocated for PRS transmission.
  • CSI-RS may be used for estimation of channel state information.
  • the CSI-RS is placed in the frequency domain or time domain.
  • Channel quality indicator (CQI), precoding matrix indicator (PMI) and rank indicator (RI) rank information such as channel quality indicator (CQI), if necessary through the estimation of the channel state using the CSI-RS As reported from the terminal.
  • the CSI-RS may be transmitted on one or more antenna ports.
  • the uplink path loss value may be estimated based on the CRS or CSI-RS or the sounding reference signal (SRS) or the physical random access channel (PRACH).
  • SRS sounding reference signal
  • PRACH physical random access channel
  • the base station when measuring the path loss value using the SRS or PRACH, calculates the received power difference between the transmission and reception points for the SRS or PRACH transmitted by the terminal, and between the transmission and reception points forming the uplink cooperative set
  • the path loss value is inferred to control the uplink transmission power of the terminal.
  • the CSI-RS is used for the measurement of the path loss, only one resource element based on antenna port 0 per pair of resource blocks can be used as a sample of the power loss.
  • the transmission period of CSI-RS is 5, 10, 20, 40, 50 ms, the number of samples used to obtain the average value of the path loss is limited, so the reliability of the measured value is low.
  • the transmission period of the CSI-RS is shortened to increase the reliability of the average value of the path loss, the data transmission efficiency may decrease due to the frequent transmission of the CSI-RS reference signal.
  • the UE when the UE measures the downlink path loss by using the CRS, eight resource elements per pair of resource block pairs may be used as a sample for measuring the path loss based on the antenna port 0.
  • the number of samples used to obtain the average value of the path loss is sufficient. The specific number of samples may be an implementation issue of the terminal within a range satisfying the accuracy of a given measurement.
  • FIG. 4 is a flowchart illustrating a method of controlling uplink transmission power for a terminal according to an embodiment of the present invention.
  • the primary TX / RX point provides RS scheduling as a secondary TX / RX point (S400).
  • the primary transmit and receive points and the secondary transmit and receive points form a cooperative set according to the cooperative multipoint method.
  • the primary transmit / receive point and the secondary transmit / receive point may cooperatively receive an uplink signal from the terminal, or may cooperatively transmit a downlink signal to the terminal.
  • the primary transmit / receive point may be a macro base station, and the secondary transmit / receive point may be a base station having less coverage than the macro base station, for example, an RRH or a pico base station.
  • the reference signal scheduling means that the transmission of the second reference signal is scheduled.
  • Transmission timing or non-transmission timing of the second reference signal is defined by the reference signal scheduling.
  • the transmission timing refers to the timing at which the secondary transceiver transmits the second reference signal
  • the non-transmission timing refers to the timing at which the secondary transceiver does not transmit the second reference signal.
  • the secondary transmission / reception point transmits or does not transmit the second reference signal.
  • reference signal scheduling defines non-transmission timing.
  • all embodiments and technical spirits of the present invention described below may be equally applicable to the case in which reference signal scheduling defines transmission timing.
  • Non-transmission timing may be defined as an offset of every muting period.
  • the muting period is set to n subframes (n ⁇ 1).
  • the muting period is set in ms.
  • the offset indicates a time point after a certain time from the start of every muting period.
  • FIG. 5 is a diagram illustrating a non-transmission timing in a muting period and an offset according to an embodiment of the present invention.
  • the reference signal scheduling means that the transmission of the second reference signal is scheduled.
  • Transmission timing or non-transmission timing of the second reference signal is defined by the reference signal scheduling.
  • the transmission timing refers to the timing at which the secondary transceiver transmits the second reference signal
  • the non-transmission timing refers to the timing at which the secondary transceiver does not transmit the second reference signal.
  • the secondary transmission / reception point transmits or does not transmit the second reference signal.
  • reference signal scheduling defines non-transmission timing.
  • all embodiments and technical spirits of the present invention described below may be equally applicable to the case in which reference signal scheduling defines transmission timing.
  • Non-transmission timing may be defined as an offset of every muting period.
  • the muting period is set to n subframes (n ⁇ 1).
  • the muting period is set in ms.
  • the offset indicates a time point after a certain time from the start of every muting period.
  • the secondary transmission / reception point sets non-transmission timing of the second reference signal based on the reference signal scheduling of the primary transmission / reception point (S405).
  • the main transceiver point transmits the reference signal scheduling information to the terminal (S410).
  • the reference signal scheduling information may be signaling used in an RRC related procedure such as radio resource control (RRC) establishment and RRC reconfiguration.
  • Reference signal scheduling information includes a parameter to be set for the path loss measurement.
  • the reference signal scheduling information includes information about a muting period and an offset indicating non-transmission timing of the secondary transmission / reception point.
  • the reference signal scheduling information includes information about the reference signal transmission power of the secondary transmission / reception point.
  • the reference signal scheduling information includes information about the size of the cooperative set, that is, the number of transmission and reception points included in the cooperative set.
  • the reference signal scheduling information includes at least one of information on the muting period and the offset of the sub transmission and reception points, information on the reference signal transmission power of the sub transmission and reception points, and information on the size of the cooperative set.
  • step S410 is described as being performed after step S405, but this is only an example, and step S405 and step S410 may be performed simultaneously or step S410 may be performed before step S405.
  • step S420 is described as being performed after step S415, this is only an example, and step S420 may be performed before step S415 according to the offset value.
  • the terminal acknowledges the non-transmission timing and the path loss (PL) measurement interval of the sub transceiver from the reference signal scheduling information received in step S410 (acknowledge).
  • the terminal measures an uplink path loss based on the first reference signal or the first reference signal and the second reference signal received in the PL measurement section (S425).
  • the PL measurement interval is a time interval designated for the UE to measure an uplink path loss value, and includes at least one non-transmission timing.
  • the length of the PL measurement interval is determined according to the number of transmission and reception points constituting the cooperative set. For example, when the primary transmit / receive point and two secondary transmit / receive points form one cooperative set, the PL measurement interval may be three consecutive subframes as shown in FIG. 6.
  • subframes #i to # (i + 2) are PL measurement intervals.
  • each transmit / receive point may have at least one unique non-transmission timing.
  • the non-transmission timing of the first subcarrier is subframes #i and # (i + 2), and the offset is 1.
  • the non-transmission timing of the second subcarrier is subframes #i and # (i + 1), and the offset is 2.
  • subframe #i the terminal receives only the reference signal of the main transmission / reception point
  • subframe # (i + 1) the terminal receives the reference signals of the main transmission point and the first sub-reception point
  • subframe # (i + 2) the terminal receives the reference signals of the main transceiver point and the second sub-receive point.
  • all transmission / reception points may transmit a reference signal.
  • the length of the PL measurement interval is determined depending on whether the reference signal transmission powers of the sub-transmission and reception points belonging to the cooperative set are the same or different. For example, if the reference signal transmission power of the sub transmission and reception points is the same, the PL measurement interval may be two subframes. Alternatively, when the reference signal transmission powers of the n sub transmission / reception points are different from each other, the PL measurement interval may be (n + 1) subframes.
  • the terminal calculates uplink transmission power based on the measured uplink path loss value (S430).
  • the terminal transmits an uplink signal to the base station at the calculated uplink transmission power (S435).
  • the UE determines uplink transmission power based on a path loss of a downlink reference signal.
  • a transmission point for transmitting a downlink signal to a terminal and a reception point for receiving an uplink signal from the terminal coincide with one base station.
  • a downlink transmission point may not coincide with an uplink reception point. That is, a transmission point and a reception point may be separated for one terminal.
  • the uplink power control method on the premise that the transmitting point and the receiving point are the same is not suitable.
  • the terminal Since a plurality of uplink paths are formed between one terminal and a plurality of receiving points, the terminal should be able to obtain uplink path loss independently for each uplink path. If a plurality of receiving points all have different physical cell IDs as in the third scenario of the CoMP system, the CoMP terminal may distinguish each receiving point, and may identify an uplink path for each receiving point. On the other hand, according to the fourth scenario, since the transmitting and receiving points simultaneously transmit a reference signal based on the same physical cell ID to the terminal in a pathloss between different transmitting and receiving points, the terminal can distinguish the reference signals. none.
  • the UE measures downlink path loss without receiving reference signals of at least one transmission / reception point every subframe. For example, referring to FIG. 6, in subframe #i, the UE measures downlink path loss without receiving reference signals of the second and third transmission and reception points.
  • the UE may obtain a downlink path loss value based on a combination of reference signals of different transmission / reception points in every subframe of the PL measurement period. By combining the downlink path loss values obtained for each subframe in this way, the UE can extract the downlink path loss values for each transmission / reception point individually. Furthermore, the terminal can obtain an uplink path loss value as a nonlinear average value of the downlink path loss values.
  • FIG. 7 is a flowchart illustrating an operation of measuring, by the terminal, an uplink power loss value using a PL measurement interval according to an embodiment of the present invention.
  • This is a case where the primary transmit / receive point and the first and second sub-receive points form a cooperative set, and the first and second sub-receive points transmit a reference signal with different powers P S1 and P S2 .
  • the muting period and the period in which the UE measures the RSRP may coincide, and the PL measurement interval has a different value depending on the size of the cooperative set.
  • the terminal receives a reference signal every subframe in the PL measurement period (S700).
  • the i-th path loss value is calculated based on the reference signal received in subframe #i in which all sub-transmitting and receiving points are the muting mode (S705). Since all the sub transmission and reception points are in the muting mode, the UE receives only the reference signals of the main transmission / reception points belonging to group 1 in subframe #i.
  • the i th path loss value is calculated by the following equation.
  • L i is the i-th path loss value for the downlink in dB unit.
  • L P is a path loss value of the reference signal of the primary transceiver.
  • the reference signal power of the reference signal is provided by an upper layer, and is an energy per resource element (EPRE) value of a downlink reference signal in dBm units.
  • EPRE energy per resource element
  • RSRP Reference Signal Received Power
  • RSRP i is the RSRP measured in subframe #i. That is, when the main transceiver point informs the terminal of the transmission power value of the reference signal, the terminal may obtain the i-th path loss value by subtracting the measured value of the power of the reference signal actually received from the reference signal transmission power value.
  • the UE calculates a (i + 1) th path loss value based on the reference signal received in the subframe # (i + 1) in which the second transmission / reception point is the muting mode (S710).
  • the primary transmit / receive point belonging to group 2 and the first secondary transmit / receive point transmit a reference signal, and thus, the (i + 1) path loss value is calculated by the following equation.
  • Equation 3 Is the (i + 1) path loss value, P P is the reference signal transmit power of the primary transceiver point, P S1 is the reference signal transmit power of the first secondary transceiver point, and L S1 is the reference of the first secondary transceiver point The path loss value for the signal.
  • P P and no P S1 is because P P is very large (eg more than 16 dB difference) compared to P S1 , and P S1 is negligibly small and can be viewed as zero.
  • I a value that can be measured by the terminal
  • P P and P S1 are values that the terminal already knows
  • L P is a value obtained from Equation 2. Accordingly, the terminal can obtain L S1 from the (i + 1) th path loss value as in the following equation.
  • the UE calculates a (i + 2) th path loss value based on the reference signal received in the subframe # (i + 2) in which the first sub transceiver point is the muting mode (S715).
  • subframe # (i + 2) the primary transmit / receive point belonging to group 3 and the second sub-transmit / receive point transmit reference signals, so that the (i + 2) th path loss value is calculated by the following equation.
  • P S2 is a reference signal transmission power of the second sub transceiver station
  • L S2 is a path loss value of the reference signal of the second secondary transceiver point.
  • Is a value that can be measured by the terminal P P and P S2 are values that the terminal already knows
  • L P is a value obtained from Equation 2. Accordingly, the UE can obtain L S2 from the (i + 2) th path loss value as in the following equation.
  • the terminal determines a path loss value L P for the reference signal of the primary transceiver point, a path loss value L S1 for the reference signal of the first secondary transceiver point, and a path loss value L S2 for the reference signal of the second secondary transceiver point. Based on the uplink path loss value PL C is obtained by the following equation (S720).
  • the uplink path loss value PL C is obtained as a non-linear average value of L P , L S1 , and L S2 .
  • the terminal calculates uplink transmission power using the uplink path loss value PL C (S725).
  • the uplink transmission power P PUSCH, C (i) is scaled by the number of antennas for which at least one PUSCH transmission is performed and the number of antennas configured according to a transmission scheme.
  • C is a serving cell to perform uplink transmission
  • i is a number of a subframe in which uplink transmission is performed with power P PUSCH, C (i).
  • the adjusted total uplink transmission power is equally divided and allocated to the antennas performing at least one PUSCH transmission.
  • PUSCH transmission power is further divided into i) a case in which PUSCH and PUCCH are not transmitted simultaneously for any serving cell C and ii) a case in which both PUSCH and PUCCH are simultaneously transmitted.
  • the UE calculates an uplink transmission power P PUSCH, C (i) defined by the following equation in subframe i for the serving cell C.
  • the UE calculates an uplink transmission power P PUSCH, C (i) defined by the following equation in subframe i for the serving cell C.
  • P CMAX, C (i ) is the maximum UE transmission power is configured for the serving cell C, Is the linear value of dB. Meanwhile, Is a value obtained by linearly converting P PUCCH (i).
  • M PUSCH, C (i) is a value representing the bandwidth of a resource allocated with a PUSCH in the subframe i for the serving cell C as the number of resource blocks.
  • P 0_PUSCH, C (i) is the sum of P 0_NOMINAL_PUSCH, C (j) and P 0_UE_PUSCH, C (j) for the serving cell C.
  • j 0.
  • j 1.
  • j 2.
  • ⁇ C (j) 1.
  • K S is a parameter provided as deltaMCS-Enabled in the upper layer for each serving cell C.
  • transmission mode 2 which is a mode for transmit diversity
  • K S 0.
  • C is the number of code blocks
  • K r is the size of the code block
  • O CQI is the number of CQI / PMI bits including the number of CRC bits
  • ⁇ PUSCH offset ⁇ CQI offset is set. Otherwise, it is always set to 1.
  • ⁇ PUSCH, C is a correction value.
  • it is determined by referring to a TPC command present in DCI format 0 or 4 for serving cell c or a TPC command in DCI format 3 / 3A that is encoded and transmitted jointly with other terminals.
  • DCI format 3 / 3A cyclic cyclic redundancy check (CRC) parity bits are scrambled with TPC-PUSCH-RNTI, so only terminals assigned the RNTI value can be checked.
  • CRC cyclic cyclic redundancy check
  • a different TPC-PUSCH-RNTI value may be allocated to each serving cell to distinguish each serving cell.
  • a different TPC-PUSCH-RNTI value may be assigned to each transmit / receive point to distinguish between the transmit and receive points.
  • f c (i) indicates a PUSCH power control adjustment state for the serving cell C.
  • the uplink path loss value PL C can be calculated using only the i th path loss value and the (i + 1) th path loss value by the operation in Equations 3, 4, and 5, Calculations according to Equations 6 and 7 may be omitted.
  • the reference signal transmission powers of the sub transceivers belonging to the cooperative set may all be the same.
  • all the sub transmission and reception points may have the same non-transmission timing as shown in FIG. 8, and may operate in a muting mode at the same non-transmission timing. Every sub-transmission point has only one non-transmission timing in each muting period. That is, the non-transmission timing limit can be reduced. Since the offset 1 of all secondary transmission and reception points are equally designated, the UE can obtain an uplink path loss value without any separate signaling indicating the offset. That is, the burden of signaling can also be reduced. In addition, the terminal may calculate the path loss for the reference signal of the main transmission and reception points and the path loss of the reference signal of the secondary transmission and reception points.
  • FIG. 9 is a flowchart illustrating an operation of measuring an uplink power loss value by a terminal according to another embodiment of the present invention. This is a case where the sub transmission points all transmit the reference signal with the same power, and as shown in FIG. 8, non-transmission timing of all the sub transmission points coincides within the PL measurement interval.
  • the terminal receives a reference signal every subframe in the PL measurement interval (S900).
  • the i-th path loss value is calculated based on the reference signal received in subframe #i in which all sub-transmitting and receiving points are the muting mode (S905).
  • the i th path loss value is calculated by the following equation.
  • L i is the i-th path loss value for the downlink in dB unit.
  • L P is a path loss value for the reference signal of the main transceiver point.
  • the reference signal power of the reference signal is provided by an upper layer, and is an energy per resource element (EPRE) value of a downlink reference signal in dBm units.
  • EPRE energy per resource element
  • RSRP is defined as the linear average over the power contributions of all resource elements carrying a reference signal within the measured frequency bandwidth under consideration. That is, when the main transceiver point informs the terminal of the transmission power value of the reference signal, the terminal may obtain the i-th path loss value by subtracting the measured value of the power of the reference signal actually received from the reference signal transmission power value.
  • the terminal calculates a (i + 1) th path loss value based on the reference signal received in subframe # (i + 1) in which all transmission and reception points transmit the reference signal (S910).
  • subframe # (i + 1) all transmission / reception points belonging to group 2 transmit a reference signal, and thus, the (i + 1) th path loss value is calculated by the following equation.
  • Equation 11 Is the (i + 1) path loss value, P P is the reference signal transmission power of the main transmission / reception point, P S is the reference signal transmission power of all secondary transmission / reception points, and L S1 is the reference signal of the first secondary transmission / reception point.
  • the path loss value for, L S2 is a path loss value for the reference signal of the second secondary transceiver point.
  • P P and P S are values that the terminal already knows, and L P is a value obtained from Equation 10. Accordingly, the terminal may obtain the nonlinear sum of the (i + 1) th path loss values L S1 and L S2 as shown in the following equation.
  • the UE can obtain the uplink path loss value PL C by the following equation (S915).
  • an uplink path loss PL value C is obtained as a non-linear mean value of P L, L S1, L S2.
  • the UE calculates uplink transmission power using the uplink path loss value PL C (S920).
  • the reference signal scheduling information includes at least one of non-Tx timing information indicating non-transmission timing of the secondary transceiver point, information on the reference signal transmission power of the secondary transceiver point, and information on the size of the cooperative set. Include.
  • the non-transmission timing information defines the non-transmission timing of the reference signal of each sub-reception point as a muting period and an offset. This is a case where the reference signal transmission power of each sub-reception point belonging to the cooperative set is different.
  • the offset indicates the point in time at which the reference signal of the sub transmission / reception point is transmitted.
  • the sub transmission / reception points operate in the muting mode at timings other than the offset within the PL measurement period.
  • Non-transmission timing information is defined individually for each sub-reception point included in the cooperative set. For example, non-transmission timing information may be defined as 4 bits as shown in the following table.
  • N is the length (number of subframes) of the PL measurement interval.
  • N may mean the size of the cooperative set, that is, the number of transmission and reception points included in the cooperative set.
  • the muting period of the specific CC is 20ms
  • the specific transmission / reception point transmits a reference signal
  • the specific sub-reception point operates in a muting mode.
  • the non-transmission timing information defines the non-transmission timing of the reference signal of each sub-reception point as a muting period. This is the case where the reference signal transmission power of each sub-reception point belonging to the cooperative set is the same.
  • the sub transmission / reception point operates in the muting mode at the end of each muting period or at the beginning of the PL measurement interval.
  • Non-transmission timing information is defined individually for each sub-reception point included in the cooperative set.
  • the non-transmission timing information may be defined as 2 bits as shown in the following table.
  • the specific sub-reception point operates in a muting mode every 20 ms.
  • the reference signal scheduling information restricts or controls the transmission of the reference signal of each sub-transmission point belonging to the cooperative set, so that the terminal can selectively receive only the reference signal of the specific transmission / reception point during the PL measurement interval.
  • FIG. 10 is a flowchart illustrating a method of controlling a transmission of a reference signal in a PL measurement section by a sub transceiver according to an example of the present invention.
  • the secondary transmission / reception point receives reference signal scheduling from the primary transmission / reception point (S1000). At this time, the secondary transmission and reception point, may transmit the information about the reference signal scheduling to the terminal (not shown in the figure).
  • the secondary transmission / reception point sets non-transmission timing according to the reference signal scheduling (S1005). Non-transmission timing is present in the PL measurement interval and is repeated periodically. Non-transmission timing is defined by a muting period and an offset, or by a muting period only.
  • the secondary transmission / reception point determines whether the current subframe is a non-transmission timing of the PL measurement interval based on the reference signal scheduling (S1010). If the current subframe is non-transmission timing, the secondary transmission and reception point operates in the muting mode (S1015). If the current subframe is not the non-transmission timing, the secondary transmission and reception point transmits a reference signal to the terminal (S1020).
  • the reference signal includes a cell specific reference signal (CRS).
  • the secondary transmission / reception point receives an uplink signal from the terminal (S1025).
  • the uplink signal includes a physical channel such as a PUSCH or a PUCCH.
  • the uplink signal is transmitted using the uplink transmission power determined by the terminal, and the uplink transmission power is determined based on the uplink path loss value determined based on the reference signal and the non-transmission timing.
  • 11 is an example of a scenario of controlling uplink transmission power according to the present invention.
  • a macro base station (eNodeB) 1100 serving as a main transmission / reception point and an RRH 1105 serving as a secondary transmission / reception point form one cooperative set and communicate with a UE UE 1110 in a CoMP scheme.
  • a transmission point for transmitting a downlink signal and a reception point for receiving an uplink signal are different. That is, the transmission point is the macro base station 1100 and the reception point is the RRH 1105.
  • a low power RRH may have a smaller transmission power than a macro base station, so that downlink coverage is small, but in the case of uplink, an RRH having a small uplink power loss may be selected.
  • the macro base station 1100 transmits a downlink signal to the terminal 1110, where a downlink path loss (PL_DL) occurs.
  • the terminal 1110 transmits an uplink signal to the RRH 1105, where an uplink path loss (PL_UL) occurs.
  • the terminal uses the downlink path loss (PL_DL) to obtain the uplink path loss (PL_UL)
  • the terminal uses the downlink path loss (PL_DL) to obtain the uplink path loss (PL_UL) to obtain the uplink path loss (PL_UL)
  • the terminal since the path itself is different, the correct uplink path loss (PL_UL) is not accurate.
  • the terminal receives the CRS from the RRH 1105 to obtain the uplink path loss (PL_UL)
  • the terminal distinguishes two CRSs because the macro base station 1100 transmits the same CRS. Can not. Therefore, the uplink path loss PL_UL cannot be accurately calculated.
  • an uplink path loss for the macro base station 1100 can be obtained at the non-transmission timing, and the non-transmission timing is determined.
  • the uplink path loss PL_UL for the RRH 1105 may be obtained at the excluded time point.
  • a macro base station (eNodeB) 1200 that is a main transmission / reception point and an RRH 1205 that is a secondary transmission / reception point form one cooperative set, and communicate with a UE UE 1210 in a CoMP scheme.
  • eNodeB eNodeB
  • RRH 1205 a secondary transmission / reception point
  • a transmission point for transmitting a downlink signal and a reception point for receiving an uplink signal are partially the same. That is, the transmission point is the macro base station 1200 and the receiving point is the macro base station 1200 and the RRH 1205.
  • the macro base station 1200 transmits a downlink signal to the terminal 1210, where a downlink path loss (PL_DL) occurs.
  • the terminal 1210 transmits an uplink signal to the macro base station 1200 and the RRH 1205, where a first uplink path loss PL_UL1 and a second uplink path loss PL_UL2 occur, respectively.
  • the terminal 1210 In order for the terminal 1210 to obtain the first uplink path loss PL_UL1, it must first receive a CRS from the macro base station 1200. However, in the cooperative multiple communication scenario 4, since the RRH 1205 also transmits the same CRS to the terminal 1210, the terminal 1210 cannot obtain an accurate first uplink path loss PL_UL1. The same applies to the second uplink path loss PL_UL1. However, according to the present invention, since the RRH 1205 operates in the muting mode at a specific non-transmission timing, the first uplink path loss PL_UL1 for the macro base station 1200 can be obtained at the non-transmission timing. The second uplink path loss PL_UL2 for the RRH 1205 may be obtained at a time other than the non-transmission timing.
  • FIG 13 is another example of a scenario of controlling uplink transmission power according to the present invention.
  • the macro base station 1300, the RRH1 1305, and the RRH2 1310 transmit downlink signals to the terminal 1210, respectively, and each of the first downlink path loss (PL_DL1) and the second downlink path loss (PL_DL2) ), A third downlink path loss PL_DL3 occurs.
  • the terminal 1210 transmits an uplink signal to the macro base station 1300, the RRH1 1305, and the RRH2 1310, and at this time, a first uplink path loss (PL_UL1) and a second uplink path loss (for each). PL_UL2) and a third uplink path loss PL_UL3.
  • the RRH1 1305 and the RRH2 1310 operate in a muting mode at the first non-transmission timing
  • the RRH2 1310 operate in a muting mode at the second non-transmission timing
  • the RRH1 1305 operates in the muting mode.
  • 3 Operates in muting mode at non-transmission timing.
  • the UE 1315 may obtain the first uplink path loss PL_UL1 for the macro base station 1300 at the first non-transmission timing, and the second uplink path loss for the RRH1 1305 at the second non-transmission timing. (PL_UL2) can be obtained, and the third uplink path loss (PL_UL3) for the RRH2 1310 can be obtained at the third non-transmission timing.
  • FIG. 14 is a block diagram illustrating a terminal and a transmission and reception point according to an embodiment of the present invention.
  • the terminal 1400 includes a terminal RF unit 1405 and a terminal processor 1410.
  • the terminal processor 1410 includes a terminal message processor 1411 and a transmission power controller 1412.
  • the terminal RF unit 1405 receives reference signal (RS) scheduling information from the main transmission / reception point 1480, receives a reference signal from the transmission / reception point 1450, and transmits an uplink signal to the transmission / reception point 1450.
  • RS reference signal
  • the transceiver point 1450 may be a secondary transceiver point.
  • the terminal message processor 1411 analyzes the information included in the RS scheduling information, obtains non-transmission timing information of the transmission / reception point 1450, and transmits the non-transmission timing information to the transmission power control unit 1412.
  • the transmit power controller 1412 may obtain an uplink path loss value according to the operation flowchart of FIG. 7 or 9.
  • the transmission power control unit 1412 may include a first downlink path loss value generated at the non-transmission timing of the transmission / reception point 1450 and a second downlink path loss value generated at the transmission timing of the transmission / reception point 1450.
  • the transmit power controller 1412 estimates a first uplink path loss value from a first downlink path loss value, a reference signal transmit power value of the transceiver point 1450, the first uplink path loss value, and A second uplink path loss value is obtained from the first downlink path loss value.
  • the transmission power controller 1412 determines a final uplink path loss value by taking a non-linear average value of the first and second uplink path loss values.
  • the transmit power controller 1412 calculates the uplink transmit power by substituting the final uplink path loss value into an equation for obtaining the uplink transmit power value as shown in Equation (8).
  • the terminal RF unit 1405 transmits an uplink signal to the transceiver point 1450 using the uplink transmission power obtained by the transmission power control unit 1412.
  • the transceiver point 1450 includes a transceiver point RF unit 1455 and a transceiver point processor 1460.
  • the transmit / receive point processor 1460 includes a transmit / receive point message processor 1462 and an RS transmission controller 1462.
  • the transceiver point RF unit 1455 transmits a reference signal to the terminal 1400 based on the non-transmission timing.
  • the transceiver point RF unit 1455 receives an uplink signal transmitted at a specific level of transmission power from the terminal 1400, and receives RS scheduling information from the primary transceiver point 1480.
  • the transceiver message processor 1541 may analyze the received uplink signal or RS scheduling information, perform an operation according to the uplink signal, or extract non-transmission timing information unique to the transceiver point 1450 to generate an RS transmission controller ( 1462) or a higher layer message.
  • the RS transmission control unit 1462 controls the transmission of the reference signal of the transmission / reception point 1450.
  • the RS transmission controller 1462 controls the transmission / reception point 1450 to operate in a muting mode at non-transmission timing.
  • the muting mode is a mode in which the RS transmission control unit 1462 sets the reference signal to zero power.
  • the RS transmission control unit 1462 controls the transmission / reception point RF unit 1455 to transmit the reference signal at other times except for the non-transmission timing, and controls the transmission / reception point RF unit 1455 not to transmit the reference signal at non-transmission timing. do.

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Abstract

The present invention relates to an apparatus and method for controlling uplink transmission power in a wireless communication system. The method for controlling uplink transmission power for a terminal includes the steps of: calculating an uplink path loss value by the terminal in a PL measurement interval designated to measure the uplink path loss value; calculating uplink transmission power based on the uplink path loss value; and transmitting an uplink signal according to the uplink transmission power. According to the present invention, each path loss value at each uplink reception point can be independently measured in a cooperative multipoint communication environment, and the uplink transmission power can be controlled by inferring the uplink path loss value for overall multiple uplink reception points.

Description

무선 통신 시스템에서 상향링크 전송 전력을 제어하는 장치 및 방법Apparatus and method for controlling uplink transmission power in a wireless communication system
본 발명은 무선통신에 관한 것으로서, 보다 상세하게는 무선 통신 시스템에서 상향링크 전송 전력을 제어하는 장치 및 방법에 관한 것이다. The present invention relates to wireless communication, and more particularly, to an apparatus and method for controlling uplink transmission power in a wireless communication system.
무선통신 시스템의 성능과 통신 용량을 높이기 위하여 다중 셀 협력(multi-cell cooperation)이 소개되고 있다. 다중 셀 협력은 협력적 다중점 송수신(cooperative multiple point transmission and reception: CoMP)라고도 한다. In order to increase the performance and communication capacity of a wireless communication system, multi-cell cooperation has been introduced. Multi-cell coordination is also referred to as cooperative multiple point transmission and reception (CoMP).
CoMP에는 인접하는 셀들이 협력하여 셀 경계의 사용자에게 간섭을 완화하는 빔 회피 기법과 인접하는 셀들이 협력하여 동일한 데이터를 전송하는 조인트 전송(joint transmission) 기법 등이 있다. CoMP includes a beam avoidance technique in which neighboring cells cooperate to mitigate interference to a user at a cell boundary, and a joint transmission technique in which neighboring cells cooperate to transmit the same data.
IEEE(Institute of Electrical and Electronics Engineers) 802.16m이나 3GPP(3rd Generation Partnership Project) LTE(long term evolution)-Advanced와 같은 차세대 무선 통신 시스템에 있어서 셀 경계에 위치하여 인접 셀로부터 심한 간섭을 받는 사용자들의 성능을 개선하는 것이 주요 요구 사항의 하나로 대두되고 있으며, 이를 해결하기 위하여 CoMP가 고려될 수가 있다.Next-generation wireless communication systems, such as Institute of Electrical and Electronics Engineers (IEEE) 802.16m or 3rd Generation Partnership Project (3GPP) long term evolution (LTE) -Advanced, are located at cell boundaries and are subject to severe interference from adjacent cells. In order to solve this problem, CoMP can be considered.
이러한 CoMP에 관하여 다양한 시나리오가 가능하다. 하나의 기지국 주변에 다수의 셀이 존재하는 인트라-사이트(intra-site) CoMP가 있고, 하나의 매크로 셀 주변에 복수의 고-전력(High-Power) 원격 무선헤드(Remote Radio Head : RRH)가 존재하는 고-전력 RRH CoMP가 있고, 하나의 매크로 셀 주변에 저-전력(low-power) RRH가 존재하되 RRH의 셀 ID와 매크로 셀의 셀 ID가 동일한 경우와 동일하지 않은 경우가 각각 존재하는 저전력 RRH CoMP가 있다. Various scenarios are possible with this CoMP. There is an intra-site CoMP with multiple cells around one base station, and a plurality of high-power remote radio heads (RRHs) around one macro cell. There are high-power RRH CoMPs that exist, and low-power RRHs exist around one macro cell, but the cell IDs of the RRHs and the cell IDs of the macro cells are not the same. There is a low power RRH CoMP.
단말이 CoMP로 동작하는 하나 또는 다수의 송수신점에 대해 상향링크 전송을 수행할 때, 상향링크 전송 전력을 결정하는 기준이 아직까지 정해진 바가 없다. When the terminal performs uplink transmission for one or more transmission / reception points operating in CoMP, a criterion for determining the uplink transmission power has not yet been determined.
본 발명의 기술적 과제는 무선 통신 시스템에서 상향링크 전송 전력을 제어하는 장치 및 방법을 제공함에 있다. An object of the present invention is to provide an apparatus and method for controlling uplink transmission power in a wireless communication system.
본 발명의 다른 기술적 과제는 PL 측정구간에서 뮤팅 모드로 동작하는 장치 및 방법을 제공함에 있다.Another object of the present invention is to provide an apparatus and method for operating in a muting mode in a PL measurement section.
본 발명의 또 다른 기술적 과제는 PL 측정구간에서 수신된 기준신호를 이용하여 상향링크 경로 손실값을 구하는 장치 및 방법을 제공함에 있다.Another object of the present invention is to provide an apparatus and method for obtaining an uplink path loss value using a reference signal received in a PL measurement section.
본 발명의 또 다른 기술적 과제는 다수의 송수신점이 단말과 통신하는 협력적 다중점 방식에서 각 송수신점에 대한 상향링크 경로 손실값을 계산하는 장치 및 방법을 제공함에 있다. Another technical problem of the present invention is to provide an apparatus and method for calculating an uplink path loss value for each transmit / receive point in a cooperative multipoint scheme in which a plurality of transmit / receive points communicate with a terminal.
본 발명의 일 양태에 따르면, 단말에 의해 수행되는 단말에 관한 상향링크 전송 전력의 제어방법을 제공한다. 상기 방법은 상기 단말이 상향링크 경로 손실(pathloss: PL) 값을 측정하도록 지정된 PL 측정구간에서 상향링크 경로 손실값을 계산하는 단계, 상기 상향링크 경로 손실값을 기반으로 상향링크 전송 전력을 계산하는 단계, 및 상향링크 신호를 상기 상향링크 전송 전력에 따라 전송하는 단계를 포함한다. 상기 PL 측정구간은 복수의 서브프레임들을 포함하고, 상기 PL 측정구간은 부 송수신점이 뮤팅 모드(muting mode)로 동작하는 비전송 타이밍을 포함하며, 상기 뮤팅 모드는 상기 부 송수신점이 셀 특정 기준 신호를 영 전력(zero-power)으로 설정하는 모드이다. According to an aspect of the present invention, there is provided a control method of uplink transmission power for a terminal performed by a terminal. The method includes the steps of calculating, by the terminal, an uplink path loss value in a designated PL measurement interval to measure an uplink pathloss (PL) value, and calculating an uplink transmission power based on the uplink path loss value. And transmitting an uplink signal according to the uplink transmission power. The PL measurement interval includes a plurality of subframes, the PL measurement interval includes non-transmission timing at which a sub-transmission point operates in a muting mode, wherein the sub-transmission point is a sub-transmission point for a cell specific reference signal. This mode is set to zero-power.
본 발명의 다른 양태에 따르면, 원격 무선 헤드에 의해 수행되는 단말에 관한 상향링크 전송 전력의 제어방법을 제공한다. 상기 방법은 상기 단말이 상향링크 경로 손실(pathloss: PL) 값을 측정하는데 사용되는 PL 측정 구간내에 포함된 비전송 타이밍에, 뮤팅 모드로 동작하는 단계, 상기 PL 측정구간에서, 상기 비전송 타이밍 이외의 시점에 셀 특정 기준 신호를 상기 단말로 전송하는 단계, 및 상기 PL 측정 구간에서 계산된 상향링크 경로 손실값에 기반한 상향링크 전송 전력으로 전송된 상향링크 신호를 상기 단말로부터 수신하는 단계를 포함한다. According to another aspect of the present invention, there is provided a method of controlling uplink transmission power for a terminal performed by a remote radio head. The method may include operating in a muting mode at a non-transmission timing included in a PL measurement interval used for measuring an uplink pathloss (PL) value by the terminal, in the PL measurement interval, in addition to the non-transmission timing. Transmitting a cell-specific reference signal to the terminal at a time point; and receiving, from the terminal, an uplink signal transmitted with uplink transmission power based on an uplink path loss value calculated in the PL measurement interval. .
본 발명에 따르면, 협력적 다중점 통신 환경에서 각 상향링크 수신점의 경로손실 값을 독립적으로 측정가능하고, 다수의 상향링크 수신점들 전체에 대한 상향링크 경로 손실 값을 유추하여 상향링크 전송 전력을 제어할 수 있다. 또한 CRS를 이용하여 상향링크의 경로 손실을 추정하게 되면 CSI-RS와 같은 다른 기준신호를 이용하는 경우에 비해 측정의 신뢰도가 증가하고, 기준신호 전송의 남발로 인한 데이터 전송효율의 감소 현상도 차단할 수 있다.According to the present invention, in the cooperative multi-point communication environment, the path loss value of each uplink receiving point can be independently measured, and the uplink transmission power is estimated by inferring the uplink path loss values of the entire uplink receiving points. Can be controlled. In addition, estimating uplink path loss using CRS increases the reliability of the measurement compared to using other reference signals such as CSI-RS, and also prevents the decrease in data transmission efficiency due to the overshoot of reference signal transmission. have.
도 1은 본 발명이 적용되는 무선통신 시스템을 나타낸 블록도이다. 1 is a block diagram showing a wireless communication system to which the present invention is applied.
도 2 및 도 3은 본 발명이 적용되는 무선 프레임의 구조를 개략적으로 나타낸 것이다. 2 and 3 schematically show the structure of a radio frame to which the present invention is applied.
도 4는 본 발명의 일 예에 따른 단말에 관한 상향링크 전송 전력의 제어방법을 설명하는 흐름도이다.4 is a flowchart illustrating a method of controlling uplink transmission power for a terminal according to an embodiment of the present invention.
도 5는 본 발명의 일 예에 따른 비전송 타이밍을 뮤팅 주기와 오프셋으로 나타낸 도면이다.5 is a diagram illustrating a non-transmission timing in a muting period and an offset according to an embodiment of the present invention.
도 6은 본 발명의 일 예에 따른 PL 측정구간에서 비전송 타이밍을 도시한 도면이다.6 is a diagram illustrating non-transmission timing in a PL measurement section according to an embodiment of the present invention.
도 7은 본 발명의 일 예에 따른 단말이 PL 측정구간을 이용하여 상향링크 전력 손실값을 측정하는 동작을 설명하는 순서도이다.7 is a flowchart illustrating an operation of measuring, by the terminal, an uplink power loss value using a PL measurement interval according to an embodiment of the present invention.
도 8은 본 발명의 일 예에 따른 비전송 타이밍을 뮤팅 주기로 나타낸 도면이다.8 is a diagram illustrating a non-transmission timing in a muting period according to an embodiment of the present invention.
도 9는 본 발명의 다른 예에 따른 단말이 상향링크 전력 손실값을 측정하는 동작을 설명하는 순서도이다.9 is a flowchart illustrating an operation of measuring an uplink power loss value by a terminal according to another embodiment of the present invention.
도 10은 본 발명의 일 예에 따른 부 송수신점이 PL 측정구간에서 기준신호의 전송을 제어하는 방법을 나타내는 순서도이다.10 is a flowchart illustrating a method of controlling a transmission of a reference signal in a PL measurement section by a sub transceiver according to an example of the present invention.
도 11은 본 발명에 따라 상향링크 전송전력을 제어하는 시나리오의 일 예이다.11 is an example of a scenario of controlling uplink transmission power according to the present invention.
도 12는 본 발명에 따라 상향링크 전송전력을 제어하는 시나리오의 다른 예이다.12 is another example of a scenario of controlling uplink transmission power according to the present invention.
도 13은 본 발명에 따라 상향링크 전송전력을 제어하는 시나리오의 또 다른 예이다.13 is another example of a scenario of controlling uplink transmission power according to the present invention.
도 14는 본 발명의 일 예에 따른 단말과 송수신점을 도시한 블록도이다.14 is a block diagram illustrating a terminal and a transmission and reception point according to an embodiment of the present invention.
이하, 본 명세서에서는 일부 실시예들을 예시적인 도면을 통해 상세하게 설명한다. 각 도면의 구성 요소들에 참조 부호를 부가함에 있어서, 동일한 구성 요소들에 대해서는 비록 다른 도면상에 표시되더라도 가능한 한 동일한 부호를 가지도록 하고 있음에 유의해야 한다. 또한, 본 명세서의 실시예를 설명함에 있어, 관련된 공지 구성 또는 기능에 대한 구체적인 설명이 본 명세서의 요지를 흐릴 수 있다고 판단되는 경우에는 그 상세한 설명은 생략한다.Hereinafter, some embodiments will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even though they are shown in different drawings. In addition, in describing the embodiments of the present specification, when it is determined that the detailed description of the related well-known configuration or function may obscure the subject matter of the present specification, the detailed description thereof will be omitted.
본 명세서는 통신 네트워크를 대상으로 설명하며, 통신 네트워크에서 이루어지는 작업은 해당 통신 네트워크를 관할하는 시스템(예를 들어 기지국)에서 네트워크를 제어하고 데이터를 송신하는 과정에서 이루어지거나, 해당 네트워크에 링크된 단말에서 작업이 이루어질 수 있다. The present specification describes a communication network, and the work performed in the communication network is performed in the process of controlling the network and transmitting data in a system (for example, a base station) that manages the communication network, or a terminal linked to the network. Work can be done in
본 발명의 실시예들에 따르면, '제어 채널을 전송한다라는 의미는 특정 채널을 통해 제어 정보가 전송되는 의미로 해석될 수 있다. 여기서, 제어 채널은 일례로 물리 하향링크 제어채널(Physical Downlink Control Channel: PDCCH) 혹은 물리 상향링크 제어채널(Physical Uplink Control Channel: PUCCH)가 될 수 있다. According to embodiments of the present invention, 'transmitting the control channel may be interpreted to mean transmitting control information through a specific channel. Here, the control channel may be, for example, a physical downlink control channel (PDCCH) or a physical uplink control channel (PUCCH).
도 1은 본 발명이 적용되는 무선통신 시스템을 나타낸 블록도이다. 1 is a block diagram showing a wireless communication system to which the present invention is applied.
도 1을 참조하면, 무선통신 시스템(10)은 음성, 패킷 데이터 등과 같은 다양한 통신 서비스를 제공하기 위해 널리 배치된다. 무선통신 시스템(10)은 적어도 하나의 기지국(11; Base Station, BS)을 포함한다. 각 기지국(11)은 특정한 지리적 영역 또는 주파수 영역(일반적으로 셀(cell)이라고 함)(15a, 15b, 15c)에 대해 통신 서비스를 제공한다. 셀(15a, 15b, 15c)은 다시 다수의 영역들(섹터라고 함)로 나누어질 수 있다. Referring to FIG. 1, the wireless communication system 10 is widely deployed to provide various communication services such as voice and packet data. The wireless communication system 10 includes at least one base station (BS) 11. Each base station 11 provides a communication service for a particular geographic area or frequency area (generally called a cell) 15a, 15b, 15c. Cells 15a, 15b, and 15c may in turn be divided into a number of regions (called sectors).
단말(12; User Equipment, UE)은 고정되거나 이동성을 가질 수 있으며, MS(mobile station), MT(mobile terminal), UT(user terminal), SS(subscriber station), 무선기기(wireless device), PDA(personal digital assistant), 무선 모뎀(wireless modem), 휴대기기(handheld device) 등 다른 용어로 불릴 수 있다. 기지국(11)은 일반적으로 단말(12)과 통신하는 지점(station)을 말하며, eNB(evolved-NodeB), BTS(Base Transceiver System), 액세스 포인트(Access Point), 펨토 기지국(femto eNB), 가내 기지국(Home eNB: HeNB), 릴레이(relay), 원격 무선 헤드(Remote Radio Head: RRH)등 다른 용어로 불릴 수 있다. 셀(15a, 15b, 15c)은 기지국(11)이 커버하는 일부 영역을 나타내는 포괄적인 의미로 해석되어야 하며, 메가셀, 매크로셀, 마이크로셀, 피코셀, 펨토셀 등 다양한 커버리지 영역을 모두 포괄하는 의미이다.The user equipment (UE) 12 may be fixed or mobile, and may include a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, and a PDA. (personal digital assistant), wireless modem (wireless modem), a handheld device (handheld device) may be called other terms. The base station 11 generally refers to a station that communicates with the terminal 12, and includes an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, an femto eNB, and a home. It may be referred to by other terms such as a base station (HeNB), a relay, a remote radio head (RRH), and the like. Cells 15a, 15b, and 15c should be interpreted in a comprehensive sense indicating some areas covered by the base station 11, and encompass all of the various coverage areas such as megacells, macrocells, microcells, picocells, and femtocells. to be.
이하에서 하향링크(downlink)는 기지국(11)에서 단말(12)로의 통신 또는 통신 경로를 의미하며, 상향링크(uplink)는 단말(12)에서 기지국(11)으로의 통신 또는 통신 경로를 의미한다. 하향링크에서 송신기는 기지국(11)의 일부분일 수 있고, 수신기는 단말(12)의 일부분일 수 있다. 상향링크에서 송신기는 단말(12)의 일부분일 수 있고, 수신기는 기지국(11)의 일부분일 수 있다. 무선통신 시스템(10)에 적용되는 다중 접속 기법에는 제한이 없다. CDMA(Code Division Multiple Access), TDMA(Time Division Multiple Access), FDMA(Frequency Division Multiple Access), OFDMA(Orthogonal Frequency Division Multiple Access), SC-FDMA(Single Carrier-FDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA와 같은 다양한 다중 접속 기법을 사용할 수 있다. 이들 변조 기법들은 통신 시스템의 다중 사용자들로부터 수신된 신호들을 복조하여 통신 시스템의 용량을 증가시킨다. 상향링크 전송 및 하향링크 전송은 서로 다른 시간을 사용하여 전송되는 TDD(Time Division Duplex) 방식 또는 서로 다른 주파수를 사용하여 전송되는 FDD(Frequency Division Duplex) 방식이 사용될 수 있다.Hereinafter, downlink refers to a communication or communication path from the base station 11 to the terminal 12, and uplink refers to a communication or communication path from the terminal 12 to the base station 11. . In downlink, the transmitter may be part of the base station 11 and the receiver may be part of the terminal 12. In uplink, the transmitter may be part of the terminal 12 and the receiver may be part of the base station 11. There is no limitation on the multiple access scheme applied to the wireless communication system 10. Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA), OFDM-FDMA, OFDM-TDMA For example, various multiple access schemes such as OFDM-CDMA may be used. These modulation techniques demodulate signals received from multiple users of a communication system to increase the capacity of the communication system. The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme transmitted using different times or a frequency division duplex (FDD) scheme transmitted using different frequencies.
무선통신 시스템(10)은 CoMP(Coordinated Multi Point) 시스템일 수 있다. CoMP 시스템은 CoMP를 지원하는 통신 시스템 또는 CoMP가 적용되는 통신 시스템을 말한다. CoMP는 다중 송수신점들(multi transmission/reception(Tx/Rx) points)에 의해 전송 또는 수신되는 신호들을 조정 또는 조합하는 기술이다. CoMP는 데이터 전송율을 증가시키고 높은 품질과 높은 수율(throughput)을 제공할 수 있다. The wireless communication system 10 may be a Coordinated Multi Point (CoMP) system. The CoMP system refers to a communication system supporting CoMP or a communication system to which CoMP is applied. CoMP is a technique for adjusting or combining signals transmitted or received by multi transmission / reception (Tx / Rx) points. CoMP can increase data rates and provide high quality and high throughput.
송수신점은 요소 반송파, 또는 셀, 또는 기지국(매크로 기지국, 피코 기지국(Pico eNB), 펨토 기지국(Femto eNB)등), 또는 원격 무선 헤드(remote radio head: RRH) 중 어느 것으로 정의될 수 있다. 또는 송수신점은 안테나 포트(antenna port)들의 집합으로 정의될 수 있다. 그리고 송수신점은 안테나 포트들의 집합에 관한 정보를 무선자원제어(radio resource control: RRC) 시그널링(signaling)으로 단말에 전송할 수 있다. 따라서 하나의 셀 내에 다수의 송수신점들을 안테나 포트들의 집합으로 정의할 수 있다. 상기 안테나 포트들의 집합 간의 교집합은 언제나 공집합이다.The transmission / reception point may be defined as a component carrier or a cell or a base station (macro base station, pico base station, femto base station, etc.), or a remote radio head (RRH). Alternatively, the transmission / reception point may be defined as a set of antenna ports. The transceiver may transmit information about the set of antenna ports to the terminal through radio resource control (RRC) signaling. Therefore, a plurality of transmission and reception points in one cell may be defined as a set of antenna ports. The intersection between the set of antenna ports is always empty.
셀(15a)의 기지국(11), 셀(15b)의 기지국(11) 그리고 셀(15c)의 기지국(11)들이 다중 송수신점들을 구성할 수 있다. 예컨대, 다중 송수신점들은 호모지니어스(homogeneous) 네트워크를 형성하는 매크로 셀의 기지국들일 수 있다. 또한, 다중 송수신점은 헤테로지니어스(heterogeneous) 네트워크를 형성하는, 매크로 셀의 기지국과 매크로 셀 내의 피코 셀의 기지국들일 수도 있다. 또한, 다중 송수신점은 매크로 셀의 기지국과 매크로 셀 내의 RRU(Remote Radio Unit)일 수도 있다. 또한, 다중 송수신점은 매크로 셀 내, 매크로 셀의 기지국에 속하는 RRH와 이종 셀(e.g. 피코 셀)의 기지국 속하는 RRH일 수도 있다.The base station 11 of the cell 15a, the base station 11 of the cell 15b and the base station 11 of the cell 15c may configure multiple transmission / reception points. For example, the multiple transmit / receive points may be base stations of a macro cell forming a homogeneous network. The multiple transmit / receive points may also be base stations of macro cells and base stations of pico cells within macro cells, forming a heterogeneous network. In addition, the multiple transmission / reception points may be a base station of the macro cell and a remote radio unit (RRU) in the macro cell. In addition, the multiple transmission / reception points may be RRHs belonging to the base station of the macro cell and RRHs belonging to the base station of the heterogeneous cell (e.g. pico cell) in the macro cell.
CoMP 시스템은 CoMP를 선택적으로 적용할 수 있다. CoMP 시스템이 CoMP를 이용하여 통신을 수행하는 모드를 CoMP 모드라 하고, 그렇지 않은 모드를 일반 모드(normal mode)라 한다. 예를 들어, CoMP가 유리하다고 판단되면, CoMP 시스템은 CoMP 모드로 동작할 수 있다. 반면 CoMP가 불리하다고 판단되면, CoMP 시스템은 일반 모드로 동작할 수 있다. The CoMP system may selectively apply CoMP. A mode in which a CoMP system performs communication using CoMP is called a CoMP mode, and a mode other than the CoMP system is called a normal mode. For example, if CoMP is determined to be advantageous, the CoMP system may operate in CoMP mode. On the other hand, if CoMP is determined to be disadvantageous, the CoMP system may operate in a normal mode.
단말(12)은 CoMP 단말일 수 있다. CoMP 단말은 CoMP 시스템을 구성하는 요소로서, CoMP 협력 집합(CoMP Cooperating Set)과 통신을 수행한다. CoMP 단말도 CoMP 시스템과 마찬가지로 CoMP 모드로 동작하거나, 일반 모드로 동작할 수 있다. 그리고 CoMP 협력 집합은 CoMP 단말에 대하여 어떤 시간-주파수 자원에서 데이터 전송에 직/간접적으로 참여하는 송수신점들의 집합이다. 예를 들어 셀(15a)의 기지국(11), 셀(15b)의 기지국(11) 그리고 셀(15c)의 기지국(11)들이 CoMP 협력 집합을 구성할 수 있다. 또한 송수신점들은 반드시 동일한 커버리지를 제공할 필요는 없다. 예를 들어, 셀(15a)의 기지국(11)은 매크로 셀을 제공하는 기지국이고, 셀(15b)의 기지국(11)은 RRH일 수 있다. The terminal 12 may be a CoMP terminal. The CoMP terminal is a component of the CoMP system and performs communication with a CoMP cooperating set. Like the CoMP system, the CoMP terminal may operate in the CoMP mode or in the normal mode. The CoMP cooperative set is a set of transmit / receive points that directly or indirectly participate in data transmission on a time-frequency resource for a CoMP terminal. For example, the base station 11 of the cell 15a, the base station 11 of the cell 15b, and the base station 11 of the cell 15c may form a CoMP cooperative set. Also, the transmit and receive points do not necessarily have to provide the same coverage. For example, base station 11 of cell 15a may be a base station providing a macro cell, and base station 11 of cell 15b may be an RRH.
데이터 전송 또는 수신에 직접 참여한다는 것은, 송수신점들이 하향링크 데이터를 CoMP 단말로 전송하거나 상향링크 데이터를 CoMP 단말로부터 수신하는 것을 의미한다. 데이터 전송 또는 수신에 간접 참여한다는 것은, 송수신점들이 하향링크 데이터를 CoMP 단말로 전송하거나 상향링크 데이터를 CoMP 단말로부터 수신하지 않지만, 사용자 스케줄링/빔포밍에 대한 결정을 내리는 데에 공헌한다는 것을 의미한다. Participating directly in data transmission or reception means that the transmitting and receiving points transmit downlink data to the CoMP terminal or receive uplink data from the CoMP terminal. Indirect participation in data transmission or reception means that the transmit / receive points do not transmit downlink data to the CoMP terminal or receive uplink data from the CoMP terminal, but contribute to making a decision about user scheduling / beamforming. .
CoMP 단말은 CoMP 협력 집합으로부터 동시에 신호를 수신하거나, CoMP 협력 집합으로 동시에 신호를 전송할 수 있다. 이때 CoMP 시스템은 CoMP 협력 집합을 구성하는 각 셀의 채널 환경을 고려하여 CoMP 협력 집합 간에 간섭 영향을 최소화한다. The CoMP terminal may simultaneously receive signals from the CoMP cooperative set or transmit signals simultaneously to the CoMP cooperative set. At this time, the CoMP system minimizes the interference effect between the CoMP cooperation sets in consideration of the channel environment of each cell constituting the CoMP cooperation set.
CoMP 단말이 상향링크 전송을 수행할 때, 수신점과 CoMP 단말간에 채널환경이 형성된다. 예를 들어 채널환경은 CoMP 단말에 할당되는 주파수 대역폭, 하향링크 경로감쇄(pathloss: PL) 등 CoMP 단말을 위한 스케줄링에 영향을 주는 파라미터들의 집합이다. 채널환경은 수신점마다 개별적으로 형성된다. 이는 채널환경이 수신점마다 다를 수 있음을 의미한다. 만약 채널환경이 수신점마다 다르면, CoMP 단말은 각 수신점에 대해 상향링크 전송 전력을 달리 설정해야 한다. 따라서 CoMP 단말은 채널환경이 각 수신점마다 어떻게 다른지 알아야 한다. When the CoMP terminal performs uplink transmission, a channel environment is formed between the reception point and the CoMP terminal. For example, the channel environment is a set of parameters that affect scheduling for a CoMP terminal, such as a frequency bandwidth allocated to the CoMP terminal and a downlink pathloss (PL). The channel environment is formed individually for each receiving point. This means that the channel environment may be different for each receiving point. If the channel environment is different for each receiving point, the CoMP terminal should set uplink transmission power differently for each receiving point. Therefore, the CoMP terminal needs to know how the channel environment is different for each receiving point.
CoMP 시스템의 운용시, 다양한 시나리오가 가능하다. 제1 시나리오는 하나의 기지국 주변에 다수의 셀이 존재하는 인트라-사이트(intra-site) CoMP 시나리오이다. 제2 시나리오는 하나의 매크로 셀 주변에 복수의 고-전력(High-Power) RRH가 존재하는 고-전력 CoMP 시나리오이다. 제3 시나리오는 하나의 매크로 셀 주변에 저-전력(low-power) RRH가 존재하되 RRH의 물리적 셀 ID와 매크로 셀의 물리적 셀 ID가 동일하지 않은 CoMP 시나리오이다. 제4 시나리오는 하나의 매크로 셀 주변에 저-전력 RRH가 존재하되 RRH의 물리적 셀 ID와 매크로 셀의 물리적 셀 ID가 동일한 CoMP 시나리오이다. 따라서 제4 시나리오에서는 셀 ID에 의해 결정되는 기준 신호의 전송 패턴도 일치한다.When operating a CoMP system, various scenarios are possible. The first scenario is an intra-site CoMP scenario in which a plurality of cells exist around one base station. The second scenario is a high-power CoMP scenario in which a plurality of high-power RRHs exist around one macro cell. The third scenario is a CoMP scenario in which a low-power RRH exists around one macro cell but the physical cell ID of the RRH and the physical cell ID of the macro cell are not the same. The fourth scenario is a CoMP scenario in which a low-power RRH exists around one macro cell, but the physical cell ID of the RRH and the physical cell ID of the macro cell are the same. Therefore, in the fourth scenario, the transmission pattern of the reference signal determined by the cell ID also matches.
본 발명이 적용되는 송수신점은 기지국, 셀 또는 RRH를 포함할 수 있다. 즉 기지국 또는 RRH가 송수신점이 될 수 있다. 한편 복수의 기지국이 다중 송수신점들이 될 수도 있고, 복수의 RRH들이 다중 송수신점들이 될 수도 있다. 물론 본 발명에서 설명되는 모든 기지국 또는 RRH의 동작은 다른 형태의 송수신점에도 동일하게 적용될 수 있다. The transmission and reception point to which the present invention is applied may include a base station, a cell, or an RRH. That is, the base station or the RRH may be a transmission / reception point. Meanwhile, the plurality of base stations may be multiple transmission / reception points, and the plurality of RRHs may be multiple transmission / reception points. Of course, the operation of all base stations or RRH described in the present invention can be equally applied to other types of transmission and reception points.
단말과 기지국 사이의 무선 인터페이스 프로토콜(radio interface protocol)의 계층들은 통신시스템에서 널리 알려진 개방형 시스템간 상호접속 (Open System Interconnection; OSI) 모델의 하위 3개 계층을 바탕으로 제1 계층(L1), 제2 계층(L2), 제3 계층(L3)으로 구분될 수 있다. 이 중에서 제1 계층에 속하는 물리계층은 물리채널(physical channel)을 이용한 정보 전송 서비스(information transfer service)를 제공한다. The layers of the radio interface protocol between the terminal and the base station are based on the lower three layers of the Open System Interconnection (OSI) model, which is well known in the communication system. It may be divided into a second layer L2 and a third layer L3. Among them, the physical layer belonging to the first layer provides an information transfer service using a physical channel.
물리계층에서 사용되는 몇몇 물리채널들이 있다. PDCCH는 하향링크 공용채널(Downlink Shared Channel: DL-SCH)의 자원 할당 및 전송 포맷, 상향링크 공용채널(Uplink Shared Channel: UL-SCH)의 자원 할당 정보, 물리하향링크 공용채널(physical downlink shared channel: PDSCH)상으로 전송되는 랜덤 액세스 응답과 같은 상위 계층 제어 메시지의 자원 할당, 임의의 단말 그룹내 개별 단말들에 대한 전송 전력 제어(transmission power control: TPC) 명령(command)의 집합 등을 나를 수 있다. 복수의 PDCCH가 제어영역 내에서 전송될 수 있으며, 단말은 복수의 PDCCH를 모니터링할 수 있다. There are several physical channels used in the physical layer. The PDCCH includes a resource allocation and transmission format of a downlink shared channel (DL-SCH), resource allocation information of an uplink shared channel (UL-SCH), and a physical downlink shared channel. Resource allocation of a higher layer control message such as a random access response transmitted on a PDSCH, a set of transmission power control (TPC) commands for individual terminals in an arbitrary terminal group, and the like. have. A plurality of PDCCHs may be transmitted in the control region, and the terminal may monitor the plurality of PDCCHs.
PDCCH에 맵핑되는 물리계층의 제어정보를 하향링크 제어정보(downlink control information; 이하 DCI)라고 한다. 즉, DCI는 PDCCH을 통해 전송된다. DCI는 상향링크 또는 하향링크 자원할당필드, 상향링크 전송전력제어 명령 필드, 페이징을 위한 제어필드, 랜덤 액세스 응답(RA response)을 지시(indicate)하기 위한 제어필드 등을 포함할 수 있다. Control information of the physical layer mapped to the PDCCH is referred to as downlink control information (DCI). That is, DCI is transmitted through the PDCCH. The DCI may include an uplink or downlink resource allocation field, an uplink transmission power control command field, a control field for paging, a control field for indicating a random access response (RA response), and the like.
DCI는 그 포맷(format)에 따라 사용용도가 다르고, DCI내에서 정의되는 필드(field)도 다르다. 표 1은 여러가지 포맷에 따른 DCI를 나타낸다. DCI has different uses according to its format, and fields defined in DCI are also different. Table 1 shows DCIs according to various formats.
표 1
DCI 포맷 설명
0 PUSCH(상향링크 그랜트)의 스케줄링에 사용됨
1 1개 셀에서의 1개의 PDSCH 코드워드(codeword)의 스케줄링에 사용됨
1A 1개 셀에서의 1개의 PDSCH 코드워드의 간략한 스케줄링 및 PDCCH 명령에 의해 초기화되는 랜덤 액세스 절차에 사용됨
1B 프리코딩 정보를 이용한 1개 셀에서의 1개의 PDSCH 코드워드의 간략한 스케줄링에 사용됨
1C 1개의 PDSCH 코드워드의 간략한 스케줄링 및 MCCH 변경의 통지를 위해 사용됨
1D 프리코딩 및 전력 오프셋 정보를 포함하는 1개 셀에서의 1개의 PDSCH 코드워드의 간략한 스케줄링에 사용됨
2 공간 다중화 모드로 구성되는 단말에 대한 PDSCH 스케줄링에 사용됨
2A 긴 지연(large delay)의 CDD 모드로 구성된 단말의 PDSCH 스케줄링에 사용됨
2B 전송모드 8(이중 레이어(layer) 전송)에서 사용됨
2C 전송모드 9(다중 레이어(layer) 전송)에서 사용됨
3 2비트의 전력 조정을 포함하는 PUCCH와 PUSCH를 위한 TPC 명령의 전송에 사용됨
3A 단일 비트 전력 조정을 포함하는 PUCCH와 PUSCH를 위한 TPC 명령의 전송에 사용됨
4 PUSCH(상향링크 그랜트)의 스케줄링에 사용됨. 특히 공간 다중화 모드로 구성되는 단말에 대한 PUSCH 스케줄링에 사용됨
Table 1
DCI format Explanation
0 Used for scheduling of PUSCH (Uplink Grant)
One Used for scheduling one PDSCH codeword in one cell
1A Used for simple scheduling of one PDSCH codeword in one cell and random access procedure initiated by PDCCH command
1B Used for simple scheduling of one PDSCH codeword in one cell using precoding information
1C Used for brief scheduling of one PDSCH codeword and notification of MCCH change
1D Used for simple scheduling of one PDSCH codeword in one cell containing precoding and power offset information
2 Used for PDSCH scheduling for UE configured in spatial multiplexing mode
2A Used for PDSCH scheduling of UE configured in long delay CDD mode
2B Used in transmission mode 8 (double layer transmission)
2C Used in transmission mode 9 (multi-layer transmission)
3 Used to transmit TPC commands for PUCCH and PUSCH with power adjustment of 2 bits
3A Used to transmit TPC commands for PUCCH and PUSCH with single bit power adjustment
4 Used for scheduling of PUSCH (Uplink Grant). In particular, it is used for PUSCH scheduling for a terminal configured in a spatial multiplexing mode.
표 1을 참조하면, DCI 포맷 0은 상향링크 스케줄링 정보이고, 하나의 PDSCH 코드워드의 스케줄링을 위한 포맷 1, 하나의 PDSCH 코드워드의 간단한(compact) 스케줄링을 위한 포맷 1A, DL-SCH의 매우 간단한 스케줄링을 위한 포맷 1C, 폐루프(Closed-loop) 공간 다중화(spatial multiplexing) 모드에서 PDSCH 스케줄링을 위한 포맷 2, 개루프(Open-loop) 공간 다중화 모드에서 PDSCH 스케줄링을 위한 포맷 2A, 상향링크 채널을 위한 TPC(Transmission Power Control) 명령의 전송을 위한 포맷 3 및 3A 등이 있다. Referring to Table 1, DCI format 0 is uplink scheduling information, format 1 for scheduling one PDSCH codeword, format 1A for compact scheduling of one PDSCH codeword, and very simple of DL-SCH. Format 1C for scheduling, format 2 for PDSCH scheduling in closed-loop spatial multiplexing mode, format 2A for PDSCH scheduling in open-loop spatial multiplexing mode, and uplink channel Formats 3 and 3A for transmission of a transmission power control (TPC) command.
DCI의 각 필드는 n개의 정보비트(information bit) a0 내지 an-1에 순차적으로 맵핑된다. 예를 들어, DCI가 총 44비트 길이의 정보비트에 맵핑된다고 하면, DCI 각 필드가 순차적으로 a0 내지 a43에 맵핑된다. DCI 포맷 0, 1A, 3, 3A는 모두 동일한 페이로드(payload) 크기를 가질 수 있다. DCI 포맷 0은 상향링크 그랜트(uplink grant)라 불릴 수도 있다. Each field of the DCI is sequentially mapped to n information bits a 0 to a n-1 . For example, if DCI is mapped to information bits of a total of 44 bits in length, each DCI field is sequentially mapped to a 0 to a 43 . DCI formats 0, 1A, 3, and 3A may all have the same payload size. DCI format 0 may be called an uplink grant.
도 2 및 도 3은 본 발명이 적용되는 무선 프레임의 구조를 개략적으로 나타낸 것이다. 2 and 3 schematically show the structure of a radio frame to which the present invention is applied.
도 2 및 도 3을 참조하면, 무선 프레임(radio frame)은 10개의 서브프레임(subframe)을 포함한다. 하나의 서브프레임은 2개의 슬롯(slot)을 포함한다. 하나의 서브 프레임을 전송하는 시간(길이)을 전송 시간 구역(Transmission Time Interval: TTI)라 한다. 예컨대, 한 서브프레임(1 subframe)의 길이는 1ms 이고, 한 슬롯(1 slot)의 길이는 0.5ms 일 수 있다. 2 and 3, a radio frame includes 10 subframes. One subframe includes two slots. The time (length) of transmitting one subframe is called a transmission time interval (TTI). For example, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms.
한 슬롯은 시간 영역에서 복수의 심벌(symbol)들을 포함할 수 있다. 예컨대, 하향링크(DownLink, DL)에서 OFDMA(Orthogonal Frequency Division Multiple Access)를 사용하는 무선 시스템의 경우에 상기 심벌은 OFDM(Orthogonal Frequency Division Multiplexing) 심벌일 수 있다. 한편, 시간 영역의 심벌 구간(symbol period)에 대한 표현이 다중 접속 방식이나 명칭에 의해 제한되는 것은 아니다. 예를 들어, 시간 영역에 있어서 복수의 심벌은 OFDM 심벌 외에 SC-FDMA(Single Carrier-Frequency Division Multiple Access) 심벌, 심벌 구간 등일 수도 있다.One slot may include a plurality of symbols in the time domain. For example, in a wireless system using orthogonal frequency division multiple access (OFDMA) in downlink (DL), the symbol may be an orthogonal frequency division multiplexing (OFDM) symbol. Meanwhile, the representation of the symbol period in the time domain is not limited by the multiple access scheme or the name. For example, the plurality of symbols in the time domain may be a Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbol, a symbol interval, or the like in addition to the OFDM symbol.
하나의 슬롯에 포함되는 OFDM 심벌의 개수는 CP(Cyclic Prefix)의 길이에 따라 달라질 수 있다. 예컨대, 정규(normal) CP인 경우에 1 슬롯은 7 OFDM 심벌을 포함하고, 확장(extended) CP인 경우에 1 슬롯은 6 OFDM 심벌을 포함할 수 있다.The number of OFDM symbols included in one slot may vary depending on the length of a cyclic prefix (CP). For example, in case of a normal CP, one slot may include 7 OFDM symbols, and in case of an extended CP, one slot may include 6 OFDM symbols.
하나의 슬롯은 주파수 영역에서 복수의 부반송파를 포함하고, 시간 영역에서 7개의 OFDM 심벌을 포함한다. 자원 블록(Resource Block, RB)은 자원 할당 단위로, 자원 블록이 주파수 영역에서 12개의 부반송파를 포함한다면, 하나의 자원 블록은 7×12개의 자원 요소(Resource Element, RE)를 포함할 수 있다.One slot includes a plurality of subcarriers in the frequency domain and seven OFDM symbols in the time domain. A resource block (RB) is a resource allocation unit. If a resource block includes 12 subcarriers in the frequency domain, one resource block may include 7 × 12 resource elements (REs).
자원 요소는 데이터 채널의 변조 심벌 또는 제어 채널의 변조 심벌이 매핑되는 가장 작은 주파수-시간 단위를 나타낸다. 한 OFDM 심벌 상에 M개의 부반송파가 있고, 한 슬롯이 N개의 OFDM 심벌을 포함한다면, 한 슬롯은 MxN 개의 자원요소를 포함한다. The resource element represents the smallest frequency-time unit to which the modulation symbol of the data channel or the modulation symbol of the control channel is mapped. If there are M subcarriers on one OFDM symbol, and one slot includes N OFDM symbols, one slot includes MxN resource elements.
무선 통신 시스템에서는 데이터의 송/수신, 시스템 동기 획득, 채널 정보 피드백 등을 위하여 상향링크 채널 또는 하향링크의 채널을 추정할 필요가 있다. 급격한 채널환경의 변화에 의하여 생기는 신호의 왜곡(distortion)을 보상하여 전송 신호를 복원하는 과정을 채널추정(channel estimation)이라고 한다. 또한 단말이 속한 셀 혹은 다른 셀에 대한 채널 상태(channel state)도 측정할 필요가 있다. 일반적으로 채널 추정 또는 채널 상태 측정을 위해서 단말과 송수신점이 상호 간에 알고 있는 기준 신호(RS: Reference Signal)를 이용한다.In a wireless communication system, it is necessary to estimate an uplink channel or a downlink channel for data transmission / reception, system synchronization acquisition, channel information feedback, and the like. The process of restoring a transmission signal by compensating for distortion of a signal caused by a sudden change in channel environment is called channel estimation. In addition, it is necessary to measure the channel state (channel state) for the cell to which the terminal belongs or other cells. In general, a reference signal (RS) that is known to the UE and the transceiver is mutually used for channel estimation or channel state measurement.
단말은 기준 신호의 정보를 알고 있기 때문에 수신된 기준 신호를 기반으로 채널을 추정하고, 채널 값을 보상해서 송수신점에서 보낸 데이터를 정확히 얻어낼 수 있다. 송수신점에서 보내는 기준 신호를 p, 기준 신호가 전송 중에 겪게 되는 채널 정보를 h, 단말에서 발생하는 열 잡음을 n, 단말이 수신한 신호를 y라 하면 y=h?p+n과 같이 나타낼 수 있다. 이때 기준 신호 p는 단말이 이미 알고 있기 때문에 LS(Least Square) 방식을 이용할 경우 수학식 1과 같이 채널 정보(
Figure PCTKR2012007902-appb-I000001
)를 추정할 수 있다.Since the terminal knows the information of the reference signal, the terminal may estimate the channel based on the received reference signal and compensate the channel value to accurately obtain the data sent from the transmission and reception point. If p is the reference signal transmitted from the transmitting and receiving point, h is channel information experienced by the reference signal during transmission, n is thermal noise generated at the terminal, and y is the signal received at the terminal, such that y = h? P + n. have. In this case, since the reference signal p is already known by the terminal, when the LS (Least Square) method is used, channel information (
Figure PCTKR2012007902-appb-I000001
) Can be estimated.
수학식 1
Figure PCTKR2012007902-appb-M000001
 Equation 1
Figure PCTKR2012007902-appb-M000001
여기서, 기준 신호 p를 이용하여 추정한 채널 추정값
Figure PCTKR2012007902-appb-I000002
는
Figure PCTKR2012007902-appb-I000003
값에 의존하게 되므로, 정확한 h값의 추정을 위해서는
Figure PCTKR2012007902-appb-I000004
이 0에 수렴시킬 필요가 있다. 많은 개수의 기준 신호를 이용함으로써
Figure PCTKR2012007902-appb-I000005
의 영향을 최소화하여 채널을 추정할 수 있다. Here, the channel estimate estimated using the reference signal p
Figure PCTKR2012007902-appb-I000002
Is
Figure PCTKR2012007902-appb-I000003
Depends on the value, so to get an accurate estimate of
Figure PCTKR2012007902-appb-I000004
You need to converge to zero. By using a large number of reference signals
Figure PCTKR2012007902-appb-I000005
The channel can be estimated by minimizing the effects of
기준신호는 모든 부반송파에 할당될 수도 있고, 데이터를 전송하는 데이터 부반송파 사이에 할당될 수도 있다. 기준 신호가 모든 부반송파에 할당되는 방식에서는 채널 추정 성능의 이득을 얻기 위하여 특정 전송 타이밍의 신호가 프리앰블(preamble)와 같은 기준 신호만으로 이루어진다. 이 경우, 데이터 전송량은 상대적으로 줄어든다. 반면, 데이터 부반송파 사이에 기준 신호가 할당되는 방식에 의하면 데이터의 전송량을 증대시킬 수 있다. The reference signal may be allocated to all subcarriers or may be allocated between data subcarriers for transmitting data. In a method in which a reference signal is allocated to all subcarriers, a signal of a specific transmission timing is composed of only a reference signal such as a preamble in order to obtain a gain of channel estimation performance. In this case, the data transfer amount is relatively reduced. On the other hand, according to the method in which a reference signal is allocated between data subcarriers, the amount of data transmission can be increased.
하향링크 기준신호로는 셀 특정 기준 신호(CRS: Cell-specific RS), MBSFN 기준 신호, 단말 특정 기준 신호(UE-specific RS), 포지셔닝 기준 신호(PRS: Positioning RS) 및 CSI(Channel State Information) 기준 신호(CSI-RS) 등이 있다. The downlink reference signal includes a cell-specific RS (CRS), an MBSFN reference signal, a UE-specific RS, a positioning reference signal (PRS), and channel state information (CSI). And a reference signal (CSI-RS).
다중 안테나 시스템에서 한 안테나의 기준 신호에 사용된 자원 요소는 다른 안테나의 기준 신호에 사용되지 않는다. 안테나 간 간섭을 주지 않기 위해서이다. 예컨대, 한 안테나당 한 기준 신호만 전송되도록 할 수 있다. In a multi-antenna system, resource elements used for reference signals of one antenna are not used for reference signals of another antenna. This is to avoid interference between antennas. For example, only one reference signal may be transmitted per antenna.
CRS는 셀 내 모든 단말에게 전송되는 기준 신호로 채널 추정에 사용된다. CRS는 PDSCH 전송을 지원하는 셀 내의 모든 하향링크 서브프레임에서 전송될 수 있다. The CRS is a reference signal transmitted to all terminals in a cell and used for channel estimation. The CRS may be transmitted in all downlink subframes in a cell supporting PDSCH transmission.
단말 특정 기준 신호는 셀 내 특정 단말 또는 특정 단말 그룹이 수신하는 기준 신호로, 특정 단말 또는 특정 단말 그룹의 데이터 복조(demodulation)에 주로 사용되므로 복조 기준 신호(Demodulation RS: DMRS)라 불릴 수 있다.The UE specific reference signal is a reference signal received by a specific terminal or a specific terminal group in a cell, and is mainly used for data demodulation of a specific terminal or a specific terminal group, and thus may be called a demodulation RS (DMRS).
MBSFN 기준 신호는 MBMS(Multimedia Broadcast Multicast Service)를 제공하기 위한 기준 신호로, MBSFN 전송을 위해 할당된 서브프레임에서 전송될 수 있다. MBSFN 기준 신호는 확장 CP 구조에서만 정의될 수 있다.The MBSFN reference signal is a reference signal for providing a multimedia broadcast multicast service (MBMS) and may be transmitted in a subframe allocated for MBSFN transmission. The MBSFN reference signal may be defined only in the extended CP structure.
PRS는 단말의 위치 측정을 위해서 사용될 수 있다. PRS는 PRS 전송을 위하여 할당된 하향링크 서브프레임 내의 자원 블록을 통해서만 전송될 수 있다. The PRS may be used for location measurement of the terminal. The PRS may be transmitted only through resource blocks in a downlink subframe allocated for PRS transmission.
CSI-RS는 채널 상태 정보의 추정을 위해 사용될 수 있다. CSI-RS는 주파수 영역 또는 시간 영역에서 배치된다. CSI-RS를 이용한 채널 상태의 추정을 통해 필요한 경우에 채널 품질 지시자(CQI: Channel Quality Indicator), 프리코딩 행렬 지시자(PMI: Precoding Matrix Indicator) 및 랭크 지시자(RI: Rank Indicator) 등이 채널 상태 정보로서 단말로부터 보고될 수 있다. CSI-RS는 하나 이상의 안테나 포트상에서 전송될 수 있다. CSI-RS may be used for estimation of channel state information. The CSI-RS is placed in the frequency domain or time domain. Channel quality indicator (CQI), precoding matrix indicator (PMI) and rank indicator (RI) rank information such as channel quality indicator (CQI), if necessary through the estimation of the channel state using the CSI-RS As reported from the terminal. The CSI-RS may be transmitted on one or more antenna ports.
상향링크 경로 손실값은 CRS 또는 CSI-RS 또는 사운딩 기준신호(sounding reference signal: SRS) 또는 물리 랜덤 액세스 채널(physical random access channel: PRACH)에 기반하여 추정될 수 있다. 예를 들어, CSI-RS를 이용하여 경로 손실 값을 측정하는 경우, 기지국은 송수신점의 CSI-RS 패턴을 단말에게 지시하고, 단말은 CSI-RS를 통해 각 송수신점에서의 하향링크 경로 손실 값을 측정하며, 이를 기반으로 하여 상향링크 전력 손실 값을 유추해 낸다.The uplink path loss value may be estimated based on the CRS or CSI-RS or the sounding reference signal (SRS) or the physical random access channel (PRACH). For example, when measuring the path loss value using the CSI-RS, the base station instructs the terminal of the CSI-RS pattern of the transceiver point, the terminal via the CSI-RS downlink path loss value at each transceiver point We estimate the uplink power loss based on this.
또는 예를 들어 SRS나 PRACH를 이용하여 경로 손실 값을 측정하는 경우, 기지국은 단말이 전송하는 SRS 또는 PRACH에 대해 송수신점들간의 수신 전력차를 계산하고, 상향링크 협력 집합을 이루는 송수신점들간의 경로 손실 값을 유추하여 단말의 상향링크 전송 전력을 제어한다. Or, for example, when measuring the path loss value using the SRS or PRACH, the base station calculates the received power difference between the transmission and reception points for the SRS or PRACH transmitted by the terminal, and between the transmission and reception points forming the uplink cooperative set The path loss value is inferred to control the uplink transmission power of the terminal.
그러나, CSI-RS가 경로 손실의 측정을 위해 사용된다면 하나의 자원블록 쌍(pair)당 안테나 포트 0을 기준으로 1개의 자원요소만 전력손실의 표본으로 사용될 수 있다. 또한 CSI-RS의 전송주기가 5, 10, 20, 40, 50 ms인 점을 감안할 때 경로 손실의 평균값을 얻는데 사용되는 표본의 수가 제한되므로 측정값의 신뢰도가 낮다. 반대로 경로 손실의 평균값의 신뢰도를 높이기 위해 CSI-RS의 전송주기를 짧게 하면 빈번한 CSI-RS 참조신호의 전송으로 데이터 전송 효율이 떨어질 수 있다. However, if the CSI-RS is used for the measurement of the path loss, only one resource element based on antenna port 0 per pair of resource blocks can be used as a sample of the power loss. In addition, given that the transmission period of CSI-RS is 5, 10, 20, 40, 50 ms, the number of samples used to obtain the average value of the path loss is limited, so the reliability of the measured value is low. On the contrary, if the transmission period of the CSI-RS is shortened to increase the reliability of the average value of the path loss, the data transmission efficiency may decrease due to the frequent transmission of the CSI-RS reference signal.
반면, 단말이 CRS를 이용하여 하향링크 경로 손실을 측정하면 경로 손실을 측정하기 위한 표본으로 안테나 포트 0을 기준으로 하나의 자원블록 쌍(pair)당 8개의 자원요소들을 채용할 수 있다. 또한 모든 서브프레임에 CRS가 전송되는 점을 감안하면 경로 손실의 평균값을 얻는데 사용되는 표본의 수는 충분하다. 구체적인 표본의 수는 주어진 측정의 정확도를 만족시키는 범위 내에서 단말의 구현이슈일 수 있다. On the other hand, when the UE measures the downlink path loss by using the CRS, eight resource elements per pair of resource block pairs may be used as a sample for measuring the path loss based on the antenna port 0. In addition, considering that the CRS is transmitted in every subframe, the number of samples used to obtain the average value of the path loss is sufficient. The specific number of samples may be an implementation issue of the terminal within a range satisfying the accuracy of a given measurement.
도 4는 본 발명의 일 예에 따른 단말에 관한 상향링크 전송 전력의 제어방법을 설명하는 흐름도이다.4 is a flowchart illustrating a method of controlling uplink transmission power for a terminal according to an embodiment of the present invention.
도 4를 참조하면, 주 송수신점(primary TX/RX point)은 부 송수신점(secondary TX/RX point)으로 기준신호(RS) 스케줄링을 제공한다(S400). 주 송수신점과 부 송수신점은 협력적 다중점 방식에 따른 협력 집합을 형성한다. 예를 들어 주 송수신점과 부 송수신점이 협력적으로 단말로부터 상향링크 신호를 수신하거나, 단말로 하향링크 신호를 협력적으로 전송할 수 있다. 주 송수신점은 매크로 기지국이고, 부 송수신점은 매크로 기지국보다 커버리지가 작은 기지국, 예를 들어 RRH나 피코 기지국일 수 있다. Referring to FIG. 4, the primary TX / RX point provides RS scheduling as a secondary TX / RX point (S400). The primary transmit and receive points and the secondary transmit and receive points form a cooperative set according to the cooperative multipoint method. For example, the primary transmit / receive point and the secondary transmit / receive point may cooperatively receive an uplink signal from the terminal, or may cooperatively transmit a downlink signal to the terminal. The primary transmit / receive point may be a macro base station, and the secondary transmit / receive point may be a base station having less coverage than the macro base station, for example, an RRH or a pico base station.
부 송수신점이 단말로 전송하는 기준신호를 제2 기준신호라 할 때, 기준신호 스케줄링은 제2 기준신호의 전송을 스케줄링함을 의미한다. 기준 신호 스케줄링에 의해 제2 기준신호의 전송 타이밍(transmission timing) 또는 비전송 타이밍(non- transmission timing)이 정의된다. 전송 타이밍은 부 송수신점이 제2 기준신호를 전송하는 타이밍을 의미하고, 비전송 타이밍은 부 송수신점이 제2 기준신호를 전송하지 않는 타이밍을 의미한다. 기준신호 스케줄링에 따른 전송 타이밍 또는 비전송 타이밍에 기반하여, 부 송수신점은 제2 기준신호를 전송하거나, 전송하지 않는다. 이하에서는 기준신호 스케줄링이 비전송 타이밍을 정의하는 것으로 가정한다. 그러나, 이하에서 설명되는 본 발명의 모든 실시예와 기술적 사상은 기준신호 스케줄링이 전송 타이밍을 정의하는 경우에도 동일하게 적용될 수 있다. When the reference signal transmitted from the secondary transceiver point to the terminal is the second reference signal, the reference signal scheduling means that the transmission of the second reference signal is scheduled. Transmission timing or non-transmission timing of the second reference signal is defined by the reference signal scheduling. The transmission timing refers to the timing at which the secondary transceiver transmits the second reference signal, and the non-transmission timing refers to the timing at which the secondary transceiver does not transmit the second reference signal. Based on the transmission timing or non-transmission timing according to the reference signal scheduling, the secondary transmission / reception point transmits or does not transmit the second reference signal. Hereinafter, it is assumed that reference signal scheduling defines non-transmission timing. However, all embodiments and technical spirits of the present invention described below may be equally applicable to the case in which reference signal scheduling defines transmission timing.
비전송 타이밍은 매 뮤팅 주기(muting period)의 오프셋(offset)으로 정의될 수 있다. 일 예로서, 뮤팅 주기는 n개의 서브프레임으로 설정된다(n≥1). 다른 예로서, 뮤팅 주기는 ms 단위로 설정된다. 오프셋은 매 뮤팅 주기의 시작시점으로부터 일정한 시간 이후의 시점을 지시한다.Non-transmission timing may be defined as an offset of every muting period. As an example, the muting period is set to n subframes (n ≧ 1). As another example, the muting period is set in ms. The offset indicates a time point after a certain time from the start of every muting period.
도 5는 본 발명의 일 예에 따른 비전송 타이밍을 뮤팅 주기와 오프셋으로 나타낸 도면이다. 5 is a diagram illustrating a non-transmission timing in a muting period and an offset according to an embodiment of the present invention.
부 송수신점이 단말로 전송하는 기준신호를 제2 기준신호라 할 때, 기준신호 스케줄링은 제2 기준신호의 전송을 스케줄링함을 의미한다. 기준 신호 스케줄링에 의해 제2 기준신호의 전송 타이밍(transmission timing) 또는 비전송 타이밍(non- transmission timing)이 정의된다. 전송 타이밍은 부 송수신점이 제2 기준신호를 전송하는 타이밍을 의미하고, 비전송 타이밍은 부 송수신점이 제2 기준신호를 전송하지 않는 타이밍을 의미한다. 기준신호 스케줄링에 따른 전송 타이밍 또는 비전송 타이밍에 기반하여, 부 송수신점은 제2 기준신호를 전송하거나, 전송하지 않는다. 이하에서는 기준신호 스케줄링이 비전송 타이밍을 정의하는 것으로 가정한다. 그러나, 이하에서 설명되는 본 발명의 모든 실시예와 기술적 사상은 기준신호 스케줄링이 전송 타이밍을 정의하는 경우에도 동일하게 적용될 수 있다. When the reference signal transmitted from the secondary transceiver point to the terminal is the second reference signal, the reference signal scheduling means that the transmission of the second reference signal is scheduled. Transmission timing or non-transmission timing of the second reference signal is defined by the reference signal scheduling. The transmission timing refers to the timing at which the secondary transceiver transmits the second reference signal, and the non-transmission timing refers to the timing at which the secondary transceiver does not transmit the second reference signal. Based on the transmission timing or non-transmission timing according to the reference signal scheduling, the secondary transmission / reception point transmits or does not transmit the second reference signal. Hereinafter, it is assumed that reference signal scheduling defines non-transmission timing. However, all embodiments and technical spirits of the present invention described below may be equally applicable to the case in which reference signal scheduling defines transmission timing.
비전송 타이밍은 매 뮤팅 주기(muting period)의 오프셋(offset)으로 정의될 수 있다. 일 예로서, 뮤팅 주기는 n개의 서브프레임으로 설정된다(n≥1). 다른 예로서, 뮤팅 주기는 ms 단위로 설정된다. 오프셋은 매 뮤팅 주기의 시작시점으로부터 일정한 시간 이후의 시점을 지시한다.Non-transmission timing may be defined as an offset of every muting period. As an example, the muting period is set to n subframes (n ≧ 1). As another example, the muting period is set in ms. The offset indicates a time point after a certain time from the start of every muting period.
다시 도 4를 참조하면, 부 송수신점은 주 송수신점의 기준신호 스케줄링에 기반하여, 제2 기준신호의 비전송 타이밍을 설정한다(S405). Referring to FIG. 4 again, the secondary transmission / reception point sets non-transmission timing of the second reference signal based on the reference signal scheduling of the primary transmission / reception point (S405).
주 송수신점은 기준신호 스케줄링 정보를 단말로 전송한다(S410). 기준신호 스케줄링 정보는 무선자원제어(radio resource control: RRC) 설정(establishment), RRC 재구성(reconfiguration)과 같은 RRC 관련 절차에서 사용되는 시그널링(signaling)일 수 있다. 기준신호 스케줄링 정보는 경로 손실 측정을 위해 설정되어야 하는 파라미터를 포함한다. 일 예로서, 기준신호 스케줄링 정보는 부 송수신점의 비전송 타이밍을 지시하는 뮤팅 주기와 오프셋에 관한 정보를 포함한다. 다른 예로서, 기준신호 스케줄링 정보는 부 송수신점의 기준신호 전송 전력에 관한 정보를 포함한다. 또 다른 예로서, 기준신호 스케줄링 정보는 협력 집합의 크기, 즉 협력 집합에 포함되는 송수신점의 개수에 관한 정보를 포함한다. 또 다른 예로서, 기준신호 스케줄링 정보는 부 송수신점의 뮤팅 주기와 오프셋에 관한 정보, 부 송수신점의 기준신호 전송 전력에 관한 정보 및 협력 집합의 크기에 관한 정보 중 적어도 하나를 포함한다. The main transceiver point transmits the reference signal scheduling information to the terminal (S410). The reference signal scheduling information may be signaling used in an RRC related procedure such as radio resource control (RRC) establishment and RRC reconfiguration. Reference signal scheduling information includes a parameter to be set for the path loss measurement. As an example, the reference signal scheduling information includes information about a muting period and an offset indicating non-transmission timing of the secondary transmission / reception point. As another example, the reference signal scheduling information includes information about the reference signal transmission power of the secondary transmission / reception point. As another example, the reference signal scheduling information includes information about the size of the cooperative set, that is, the number of transmission and reception points included in the cooperative set. As another example, the reference signal scheduling information includes at least one of information on the muting period and the offset of the sub transmission and reception points, information on the reference signal transmission power of the sub transmission and reception points, and information on the size of the cooperative set.
도 4에서는 단계 S410이 단계 S405 다음에 수행되는 것으로 기재되어 있으나, 이는 예시일 뿐이고, 단계 S405와 단계 S410가 동시에 수행되거나 단계 S410이 단계 S405보다 먼저 수행될 수도 있다. In FIG. 4, step S410 is described as being performed after step S405, but this is only an example, and step S405 and step S410 may be performed simultaneously or step S410 may be performed before step S405.
설정된 비전송 타이밍에, 주 송수신점만이 주 기준신호를 단말로 전송하고, 부 송수신점은 뮤팅 모드(muting mode)로 동작한다(S415). 그리고 전송 타이밍에, 주 송수신점은 제1 기준신호를, 부 송수신점은 제2 기준신호를 단말로 전송한다(S420). 즉, 부 송수신점은 비전송 타이밍에는 뮤팅 모드로 동작하고, 전송 타이밍에는 제2 기준신호를 단말로 전송한다. 뮤팅 모드는 부 송수신점이 제2 기준신호를 전송하지 않는 모드이다. 또는 뮤팅 모드는 부 송수신점이 제2 기준신호의 전송전력을 0으로 설정하는 모드이다. 제2 기준신호의 뮤팅은 영 전력(zero-power) 기준신호 전송이라고 불릴 수도 있다. 단계 S420이 단계 S415 다음에 수행되는 것으로 기재되어 있으나, 이는 예시일 뿐이고, 오프셋 값에 따라 단계 S420이 단계 S415보다 먼저 수행될 수도 있다. At the set non-transmission timing, only the main transmission / reception point transmits the main reference signal to the terminal, and the sub transmission / reception point operates in a muting mode (S415). At the transmission timing, the main transmission / reception point transmits the first reference signal and the sub transmission / reception point transmits the second reference signal to the terminal (S420). That is, the secondary transmission and reception point operates in the muting mode at the non-transmission timing, and transmits the second reference signal to the terminal at the transmission timing. The muting mode is a mode in which the secondary transceiver does not transmit the second reference signal. Alternatively, the muting mode is a mode in which the secondary transceiver sets the transmit power of the second reference signal to zero. Muting the second reference signal may be referred to as zero-power reference signal transmission. Although step S420 is described as being performed after step S415, this is only an example, and step S420 may be performed before step S415 according to the offset value.
단말은 단계 S410에서 수신한 기준신호 스케줄링 정보로부터 부 송수신점의 비전송 타이밍과 경로손실(PL) 측정구간을 인지한다(acknowledge). 그리고 단말은 PL 측정구간에서 수신된 제1 기준신호 또는 제1 기준신호 및 제2 기준신호를 기반으로 상향링크 경로 손실값을 측정한다(S425). PL 측정구간은 단말이 상향링크 경로 손실값을 측정하도록 지정된 시간구간으로서, 적어도 하나의 비전송 타이밍을 포함한다. 일 예로서, PL 측정구간은 협력 집합을 구성하는 송수신점들의 개수에 따라 그 길이가 결정된다. 예를 들어, 주 송수신점과, 2개의 부 송수신점들이 하나의 협력 집합을 구성하는 경우, PL 측정구간은 도 6과 같이 3개의 연속적인 서브프레임들이 될 수 있다. The terminal acknowledges the non-transmission timing and the path loss (PL) measurement interval of the sub transceiver from the reference signal scheduling information received in step S410 (acknowledge). The terminal measures an uplink path loss based on the first reference signal or the first reference signal and the second reference signal received in the PL measurement section (S425). The PL measurement interval is a time interval designated for the UE to measure an uplink path loss value, and includes at least one non-transmission timing. As an example, the length of the PL measurement interval is determined according to the number of transmission and reception points constituting the cooperative set. For example, when the primary transmit / receive point and two secondary transmit / receive points form one cooperative set, the PL measurement interval may be three consecutive subframes as shown in FIG. 6.
도 6을 참조하면, 서브프레임 #i부터 #(i+2)까지가 PL 측정구간이다. 주 송수신점, 제1 부 송수신점 및 제2 부 송수신점들이 하나의 협력 집합을 구성할 때, 각 송수신점들은 적어도 하나의 고유한 비전송 타이밍을 가질 수 있다. 예를 들어, 제1 부송수신점의 비전송 타이밍은 서브프레임 #i와 #(i+2)이고, 오프셋은 1이 된다. 제2 부송수신점의 비전송 타이밍은 서브프레임 #i와 #(i+1)이고, 오프셋은 2가 된다. 단말의 관점에서 보면, 서브프레임 #i에서 단말은 주 송수신점의 기준신호만을 수신하고, 서브프레임 #(i+1)에서 단말은 주송수신점 및 제1 부송수신점의 기준신호를 수신하며, 서브프레임 #(i+2)에서 단말은 주 송수신점 및 제2 부송수신점의 기준신호를 수신한다. PL 측정구간 이외의 서브프레임에서는 모든 송수신점들이 기준신호를 전송할 수 있다. Referring to FIG. 6, subframes #i to # (i + 2) are PL measurement intervals. When the primary transmit / receive point, the first sub-receive point and the second sub-receive point constitute one cooperative set, each transmit / receive point may have at least one unique non-transmission timing. For example, the non-transmission timing of the first subcarrier is subframes #i and # (i + 2), and the offset is 1. The non-transmission timing of the second subcarrier is subframes #i and # (i + 1), and the offset is 2. From the point of view of the terminal, in subframe #i, the terminal receives only the reference signal of the main transmission / reception point, and in subframe # (i + 1), the terminal receives the reference signals of the main transmission point and the first sub-reception point, In subframe # (i + 2), the terminal receives the reference signals of the main transceiver point and the second sub-receive point. In subframes other than the PL measurement interval, all transmission / reception points may transmit a reference signal.
다른 예로서, PL 측정구간은 협력 집합에 속하는 부 송수신점들의 기준신호 전송전력이 동일한지, 다른지에 따라 그 길이가 결정된다. 예를 들어, 부 송수신점들의 기준신호 전송전력이 동일하면, PL 측정구간은 2개 서브프레임일 수 있다. 또는 n개의 부 송수신점들의 기준신호 전송전력이 서로 다르면, PL 측정구간은 (n+1)개의 서브프레임일 수 있다. As another example, the length of the PL measurement interval is determined depending on whether the reference signal transmission powers of the sub-transmission and reception points belonging to the cooperative set are the same or different. For example, if the reference signal transmission power of the sub transmission and reception points is the same, the PL measurement interval may be two subframes. Alternatively, when the reference signal transmission powers of the n sub transmission / reception points are different from each other, the PL measurement interval may be (n + 1) subframes.
다시 도 4를 참조하면, 단말은 측정된 상향링크 경로 손실값에 기반하여, 상향링크 전송전력을 계산한다(S430). Referring to FIG. 4 again, the terminal calculates uplink transmission power based on the measured uplink path loss value (S430).
단말은 계산된 상향링크 전송전력으로 상향링크 신호를 기지국으로 전송한다(S435). The terminal transmits an uplink signal to the base station at the calculated uplink transmission power (S435).
이하에서, 단말이 PL 측정구간에 기반하여 상향링크 경로 손실값을 측정하는 방법에 관하여 보다 상세히 설명된다. Hereinafter, a method of measuring an uplink path loss value based on a PL measurement interval by the terminal will be described in more detail.
Non-CoMP 방식과 같이 단말이 하나의 기지국과 하향링크와 상향링크를 형성하는 시스템에서, 단말은 하향링크 기준신호의 경로 손실을 기준으로 상향링크 전송전력을 결정한다. 그러나, 이는 단말로 하향링크 신호를 전송하는 전송점과 단말로부터 상향링크 신호를 수신하는 수신점이 하나의 기지국으로 일치함을 전제로 한다. 그런데 CoMP 방식에서는 하향링크 송신점이 상향링크 수신점과 일치하지 않는 현상이 발생할 수 있다. 즉, 하나의 단말에 대해 송신점과 수신점이 분리될 수 있다. 이때는 송신점과 수신점이 동일할 것을 전제로 하는 상향링크 전력제어 방식은 적합하지 않다. 또한 전송전력이 서로 다른 저전력 RRH와 매크로 기지국이 공존하는 헤테로지니어스 네트워크에서, 저전력 RRH와 매크로 기지국이 모두 수신점으로 동작하는 경우, 어느 수신점을 기준으로 상향링크 전력을 제어할지 모호하다. In a system in which a UE forms downlink and uplink with one base station as in the non-CoMP scheme, the UE determines uplink transmission power based on a path loss of a downlink reference signal. However, this assumes that a transmission point for transmitting a downlink signal to a terminal and a reception point for receiving an uplink signal from the terminal coincide with one base station. However, in the CoMP scheme, a downlink transmission point may not coincide with an uplink reception point. That is, a transmission point and a reception point may be separated for one terminal. In this case, the uplink power control method on the premise that the transmitting point and the receiving point are the same is not suitable. In addition, in a heterogeneous network in which a low power RRH and a macro base station coexist with different transmission powers, when both the low power RRH and the macro base station operate as reception points, it is ambiguous about which reception point to control the uplink power.
하나의 단말과 다수의 수신점들간에 다수의 상향링크 경로가 형성되므로, 단말은 각 상향링크 경로에 대해 독립적으로 상향링크 경로 손실을 구할 수 있어야 한다. CoMP 시스템의 제3 시나리오와 같이 다수의 수신점들이 모두 서로 다른 물리적 셀 ID를 가지면, CoMP 단말은 각 수신점을 구별할 수 있고, 각 수신점마다 상향링크 경로를 구별할 수 있다. 반면, 제4 시나리오에 따르면, 서로 다른 송수신점들간에 경로 손실(pathloss)이 서로 다른 상황에서 송수신점들이 동시에 동일한 물리적 셀 ID에 기반한 기준 신호를 단말로 전송하므로, 단말은 기준 신호들을 구별할 수 없다. Since a plurality of uplink paths are formed between one terminal and a plurality of receiving points, the terminal should be able to obtain uplink path loss independently for each uplink path. If a plurality of receiving points all have different physical cell IDs as in the third scenario of the CoMP system, the CoMP terminal may distinguish each receiving point, and may identify an uplink path for each receiving point. On the other hand, according to the fourth scenario, since the transmitting and receiving points simultaneously transmit a reference signal based on the same physical cell ID to the terminal in a pathloss between different transmitting and receiving points, the terminal can distinguish the reference signals. none.
다만, 뮤팅 모드가 허용되는 PL 측정구간에서는 단말은 매 서브프레임마다 적어도 하나의 송수신점의 기준신호를 수신하지 않은 채로 하향링크 경로 손실을 측정한다. 예를 들어, 도 6을 참조할 때, 서브프레임 #i에서 단말은 제2, 제3 송수신점의 기준신호를 수신하지 않은 상태에서 하향링크 경로 손실을 측정한다. 이와 같은 방식에 의하면 단말은 PL 측정구간의 매 서브프레임마다 다른 송수신점들의 기준신호의 조합에 기반한 하향링크 경로 손실값을 얻을 수 있다. 이렇게 각 서브프레임마다 얻어진 하향링크 경로 손실값들을 조합하면, 단말은 각 송수신점에 대한 하향링크 경로 손실값을 개별적으로 추출해낼 수 있다. 나아가 단말은 상기 하향링크 경로 손실값들에 대한 비선형 평균치(nonlinear average value)로서 상향링크 경로 손실값을 구할 수 있다. However, in the PL measurement interval in which the muting mode is allowed, the UE measures downlink path loss without receiving reference signals of at least one transmission / reception point every subframe. For example, referring to FIG. 6, in subframe #i, the UE measures downlink path loss without receiving reference signals of the second and third transmission and reception points. According to this method, the UE may obtain a downlink path loss value based on a combination of reference signals of different transmission / reception points in every subframe of the PL measurement period. By combining the downlink path loss values obtained for each subframe in this way, the UE can extract the downlink path loss values for each transmission / reception point individually. Furthermore, the terminal can obtain an uplink path loss value as a nonlinear average value of the downlink path loss values.
도 7은 본 발명의 일 예에 따른 단말이 PL 측정구간을 이용하여 상향링크 전력 손실값을 측정하는 동작을 설명하는 순서도이다. 이는 주 송수신점과 제1 및 제2 부 송수신점이 협력 집합을 이루고, 제1 및 제2 부 송수신점들이 서로 다른 전력 PS1, PS2로 기준 신호를 전송하는 경우이다. 뮤팅 주기와 단말이 RSRP를 측정하는 주기는 일치할 수 있으며, PL 측정구간은 협력 집합의 크기에 따라 다른 값을 가진다. 7 is a flowchart illustrating an operation of measuring, by the terminal, an uplink power loss value using a PL measurement interval according to an embodiment of the present invention. This is a case where the primary transmit / receive point and the first and second sub-receive points form a cooperative set, and the first and second sub-receive points transmit a reference signal with different powers P S1 and P S2 . The muting period and the period in which the UE measures the RSRP may coincide, and the PL measurement interval has a different value depending on the size of the cooperative set.
도 7을 참조하면, 단말은 PL 측정구간에서 매 서브프레임마다 기준신호를 수신한다(S700). Referring to FIG. 7, the terminal receives a reference signal every subframe in the PL measurement period (S700).
모든 부 송수신점들이 뮤팅 모드인 서브프레임 #i에서 수신된 기준신호를 기반으로 제i 경로 손실값을 계산한다(S705). 모든 부 송수신점들이 뮤팅 모드이므로, 서브프레임 #i에서는 단말은 그룹 1에 속하는 주 송수신점의 기준신호만을 수신한다. 제i 경로 손실값은 다음의 수학식에 의해 계산된다. The i-th path loss value is calculated based on the reference signal received in subframe #i in which all sub-transmitting and receiving points are the muting mode (S705). Since all the sub transmission and reception points are in the muting mode, the UE receives only the reference signals of the main transmission / reception points belonging to group 1 in subframe #i. The i th path loss value is calculated by the following equation.
수학식 2
Figure PCTKR2012007902-appb-M000002
 Equation 2
Figure PCTKR2012007902-appb-M000002
수학식 2를 참조하면, Li는 하향링크에 대한 제i 경로 손실값으로서 dB단위이다. LP는 주(Primary) 송수신점의 기준신호에 대한 경로 손실값이다. 서브프레임 #i에서는 주 송수신점만이 기준신호를 전송하므로, Li=LP이다. 기준신호의 전송전력(referenceSignalPower)은 상위계층에서 제공되며, 하향링크 기준신호의 자원요소당 에너지(Energy Per Resource Element: EPRE)값으로 dBm 단위이다. 기준신호 대 수신전력(Reference Signal Received Power: RSRP)은 고려되는 측정 주파수 대역폭(considered measurement frequency bandwidth)내의 기준신호를 운반하는 모든 자원요소들의 전력 기여들에 대한 선형 평균으로 정의된다. RSRPi는 서브프레임 #i에서 측정된 RSRP이다. 즉 주 송수신점이 기준신호의 전송전력 값을 단말에게 알려주면, 단말은 기준신호 전송전력 값에서 실제 수신한 기준신호의 전력을 측정한 값을 뺌으로써 제i 경로 손실값을 얻을 수 있다. Referring to Equation 2, L i is the i-th path loss value for the downlink in dB unit. L P is a path loss value of the reference signal of the primary transceiver. In subframe #i, since only the main transmission / reception point transmits a reference signal, L i = L P. The reference signal power of the reference signal is provided by an upper layer, and is an energy per resource element (EPRE) value of a downlink reference signal in dBm units. Reference Signal Received Power (RSRP) is defined as the linear average over the power contributions of all resource elements carrying a reference signal within the considered measurement frequency bandwidth. RSRP i is the RSRP measured in subframe #i. That is, when the main transceiver point informs the terminal of the transmission power value of the reference signal, the terminal may obtain the i-th path loss value by subtracting the measured value of the power of the reference signal actually received from the reference signal transmission power value.
다음으로, 단말은 제2 부 송수신점이 뮤팅 모드인 서브프레임 #(i+1)에서 수신된 기준신호를 기반으로 제(i+1) 경로 손실값을 계산한다(S710). 서브프레임 #(i+1)에서는 그룹 2에 속하는 주 송수신점과 제1 부 송수신점이 기준신호를 전송하므로, 제(i+1) 경로 손실값은 다음의 수학식에 의해 계산된다. Next, the UE calculates a (i + 1) th path loss value based on the reference signal received in the subframe # (i + 1) in which the second transmission / reception point is the muting mode (S710). In subframe # (i + 1), the primary transmit / receive point belonging to group 2 and the first secondary transmit / receive point transmit a reference signal, and thus, the (i + 1) path loss value is calculated by the following equation.
수학식 3
Figure PCTKR2012007902-appb-M000003
 Equation 3
Figure PCTKR2012007902-appb-M000003
수학식 3을 참조하면,
Figure PCTKR2012007902-appb-I000006
는 제(i+1) 경로 손실값이고, PP는 주 송수신점의 기준신호 전송전력이며, PS1은 제1 부 송수신점의 기준신호 전송전력이고, LS1은 제1 부 송수신점의 기준신호에 대한 경로 손실값이다. 분자에서, PP만 있고 PS1이 없는 이유는 PP가 PS1에 비해 매우 커서(예를 들어 16dB이상 차이가 남), PS1은 무시할 만큼 작아 0으로 볼 수 있기 때문이다.Referring to Equation 3,
Figure PCTKR2012007902-appb-I000006
Is the (i + 1) path loss value, P P is the reference signal transmit power of the primary transceiver point, P S1 is the reference signal transmit power of the first secondary transceiver point, and L S1 is the reference of the first secondary transceiver point The path loss value for the signal. In the numerator, only P P and no P S1 is because P P is very large (eg more than 16 dB difference) compared to P S1 , and P S1 is negligibly small and can be viewed as zero.
Figure PCTKR2012007902-appb-I000007
는 단말이 측정가능한 값이고, PP, PS1은 모두 단말이 이미 알고 있는 값이며, LP는 수학식 2에서 구해진 값이다. 따라서, 단말은 제(i+1) 경로 손실값으로부터 LS1를 다음의 수학식과 같이 구할 수 있다.
Figure PCTKR2012007902-appb-I000007
Is a value that can be measured by the terminal, P P and P S1 are values that the terminal already knows, and L P is a value obtained from Equation 2. Accordingly, the terminal can obtain L S1 from the (i + 1) th path loss value as in the following equation.
수학식 4
Figure PCTKR2012007902-appb-M000004
 Equation 4
Figure PCTKR2012007902-appb-M000004
다음으로, 단말은 제1 부 송수신점이 뮤팅 모드인 서브프레임 #(i+2)에서 수신된 기준신호를 기반으로 제(i+2) 경로 손실값을 계산한다(S715). 서브프레임 #(i+2)에서는 그룹 3에 속하는 주 송수신점과 제2 부 송수신점이 기준신호를 전송하므로, 제(i+2) 경로 손실값은 다음의 수학식에 의해 계산된다. Next, the UE calculates a (i + 2) th path loss value based on the reference signal received in the subframe # (i + 2) in which the first sub transceiver point is the muting mode (S715). In subframe # (i + 2), the primary transmit / receive point belonging to group 3 and the second sub-transmit / receive point transmit reference signals, so that the (i + 2) th path loss value is calculated by the following equation.
수학식 5
Figure PCTKR2012007902-appb-M000005
 Equation 5
Figure PCTKR2012007902-appb-M000005
수학식 5를 참조하면,
Figure PCTKR2012007902-appb-I000008
는 제(i+2) 경로 손실값이고, PS2는 제2 부 송수신점의 기준신호 전송전력이고, LS2은 제2 부 송수신점의 기준신호에 대한 경로 손실값이다.
Figure PCTKR2012007902-appb-I000009
는 단말이 측정가능한 값이고, PP, PS2는 모두 단말이 이미 알고 있는 값이며, LP는 수학식 2에서 구해진 값이다. 따라서, 단말은 제(i+2) 경로 손실값으로부터 LS2를 다음의 수학식과 같이 구할 수 있다.Referring to Equation 5,
Figure PCTKR2012007902-appb-I000008
Is a (i + 2) th path loss value, P S2 is a reference signal transmission power of the second sub transceiver station, and L S2 is a path loss value of the reference signal of the second secondary transceiver point.
Figure PCTKR2012007902-appb-I000009
Is a value that can be measured by the terminal, P P and P S2 are values that the terminal already knows, and L P is a value obtained from Equation 2. Accordingly, the UE can obtain L S2 from the (i + 2) th path loss value as in the following equation.
수학식 6
Figure PCTKR2012007902-appb-M000006
 Equation 6
Figure PCTKR2012007902-appb-M000006
단말은 주 송수신점의 기준신호에 대한 경로 손실값 LP와, 제1 부 송수신점의 기준신호에 대한 경로 손실값 LS1과, 제2 부 송수신점의 기준신호에 대한 경로 손실값 LS2를 기반으로, 상향링크 경로 손실값 PLC를 다음과 같은 수학식에 의해 구한다(S720).The terminal determines a path loss value L P for the reference signal of the primary transceiver point, a path loss value L S1 for the reference signal of the first secondary transceiver point, and a path loss value L S2 for the reference signal of the second secondary transceiver point. Based on the uplink path loss value PL C is obtained by the following equation (S720).
수학식 7
Figure PCTKR2012007902-appb-M000007
 Equation 7
Figure PCTKR2012007902-appb-M000007
수학식 7을 참조하면, 상향링크 경로 손실값 PLC는 LP, LS1, LS2의 비선형 평균치로써 구해진다. Referring to Equation 7, the uplink path loss value PL C is obtained as a non-linear average value of L P , L S1 , and L S2 .
단말은 상향링크 경로 손실값 PLC를 이용하여 상향링크 전송 전력을 계산한다(S725). PUSCH의 경우, 상향링크 전송 전력 PPUSCH,C(i)는 적어도 하나의 PUSCH 전송이 이루어지는 안테나의 개수와 전송방식에 따라 구성된 안테나의 개수로 조정(scale)된다. C는 상향링크 전송을 수행할 서빙셀이고, i는 전력 PPUSCH,C(i)로 상향링크 전송이 수행되는 서브프레임의 번호이다. 그리고, 조정된 전체 상향링크 전송 전력은 적어도 하나의 PUSCH 전송이 이루어지는 안테나에 대하여 동등하게 나누어져 할당된다. The terminal calculates uplink transmission power using the uplink path loss value PL C (S725). In the case of the PUSCH, the uplink transmission power P PUSCH, C (i) is scaled by the number of antennas for which at least one PUSCH transmission is performed and the number of antennas configured according to a transmission scheme. C is a serving cell to perform uplink transmission, and i is a number of a subframe in which uplink transmission is performed with power P PUSCH, C (i). The adjusted total uplink transmission power is equally divided and allocated to the antennas performing at least one PUSCH transmission.
PUSCH 전송 전력은 다시 임의의 서빙셀 C에 대하여 i) PUSCH와 PUCCH를 동시에 전송하지 않는 경우와 ii) PUSCH와 PUCCH를 동시에 전송하는 경우로 나뉜다.PUSCH transmission power is further divided into i) a case in which PUSCH and PUCCH are not transmitted simultaneously for any serving cell C and ii) a case in which both PUSCH and PUCCH are simultaneously transmitted.
i)의 경우, 단말은 서빙셀 C에 대한 서브프레임 i에서 아래의 수학식에 의해 정의되는 상향링크 전송 전력 PPUSCH,C(i)을 계산한다.In case of i), the UE calculates an uplink transmission power P PUSCH, C (i) defined by the following equation in subframe i for the serving cell C.
수학식 8
Figure PCTKR2012007902-appb-M000008
 Equation 8
Figure PCTKR2012007902-appb-M000008
ii)의 경우, 단말은 서빙셀 C에 대한 서브프레임 i에서 아래의 수학식에 의해 정의되는 상향링크 전송 전력 PPUSCH,C(i)을 계산한다.In the case of ii), the UE calculates an uplink transmission power P PUSCH, C (i) defined by the following equation in subframe i for the serving cell C.
수학식 9
Figure PCTKR2012007902-appb-M000009
 Equation 9
Figure PCTKR2012007902-appb-M000009
수학식 8과 수학식 9를 참조하면, PCMAX,C(i)는 서빙셀 C에 대하여 구성된 최대 단말 송출전력이고,
Figure PCTKR2012007902-appb-I000010
는 dB값을 선형으로 변환한 값이다. 한편,
Figure PCTKR2012007902-appb-I000011
는 PPUCCH(i)를 선형으로 변환한 값이다. MPUSCH,C(i)는 서빙셀 C에 대한 서브프레임 i에서 PUSCH가 할당된 자원의 대역폭을 자원블록의 개수로 표현한 값이다. Referring to Equation 8 and Equation 9, P CMAX, C (i ) is the maximum UE transmission power is configured for the serving cell C,
Figure PCTKR2012007902-appb-I000010
Is the linear value of dB. Meanwhile,
Figure PCTKR2012007902-appb-I000011
Is a value obtained by linearly converting P PUCCH (i). M PUSCH, C (i) is a value representing the bandwidth of a resource allocated with a PUSCH in the subframe i for the serving cell C as the number of resource blocks.
P0_PUSCH,C(i)는 서빙셀 C에 대한 P0_NOMINAL_PUSCH,C(j)와 P0_UE_PUSCH,C(j)의 합이다. 예를 들어, 반지속적(semi-persistent) 그랜드 PUSCH (재)전송인 경우 j=0값을 갖는다. 반면에, 동적 스케줄링되는(dynamic scheduled) 그랜드 PUSCH (재)전송인 경우 j=1값을 갖는다. j=0 또는 1인 경우 상위계층에 의해 시그널링된다. 그리고, 랜덤 액세스 응답 그랜트 PUSCH (재)전송인 경우 j=2값을 갖는다. 또한 랜덤 액세스 응답 그랜트 PUSCH (재)전송인 경우 P0_UE_PUSCH,C(2)=0이고 P0_NOMINAL_PUSCH,C(2)=P0_PRE+ΔPREAMBLE_Msg3이다, 여기서 파라미터 preambleInitialReceivedTargetPower(P0_PRE)와 ΔPREAMBLE_Msg3는 상위계층으로부터 시그널링된다.P 0_PUSCH, C (i) is the sum of P 0_NOMINAL_PUSCH, C (j) and P 0_UE_PUSCH, C (j) for the serving cell C. For example, in case of semi-persistent grand PUSCH (re) transmission, it has a value of j = 0. On the other hand, in case of dynamic scheduled grand PUSCH (re) transmission, j = 1. If j = 0 or 1, it is signaled by a higher layer. And, in case of random access response grant PUSCH (re) transmission, j = 2. In addition, for random access response grant PUSCH (re) transmission, P 0_UE_PUSCH, C (2) = 0 and P 0_NOMINAL_PUSCH, C (2) = P 0_PRE + Δ PREAMBLE_Msg3 , where the parameters preambleInitialReceivedTargetPower (P 0_PRE ) and Δ PREAMBLE_Msg3 Is signaled from.
만일 j=0 또는 1인 경우, 상위계층에서 제공되는 3비트 파라미터에 의해 αC∈{0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1} 값들 중에서 하나가 선택될 수 있다. j=2인 경우 항상 αC(j)=1이다. If j = 0 or 1, one of the values of α C ∈ {0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1} may be selected by the 3-bit parameter provided in the upper layer. When j = 2, α C (j) = 1.
ΔTF,C(i)=10log10((2BPRE·Ks-1)·βPUSCH offset)으로서, 변조 및 코딩 방식(Modulation and Coding Scheme: MCS)에 의한 영향을 반영하기 위한 파라미터이다. 여기서, KS는 각 서빙셀 C에 대하여 상위계층에서 deltaMCS-Enabled으로 제공되는 파라미터이다. 전송 다이버시티를 위한 모드인 전송모드 2인 경우 언제나 KS=0이다. UL-SCH 데이터 없이 PUSCH를 통해 제어정보만이 전송되는 경우 BPRE=OCQI/NRE이며, 상기 이외의 모든 경우에는 BPRE=
Figure PCTKR2012007902-appb-I000012
이다. 여기서, C는 코드블록의 개수이며, Kr은 코드블록의 크기이며, OCQI는 CRC 비트수를 포함한 CQI/PMI 비트 개수이며, NRE는 결정된 자원요소들의 개수이다. 즉, NRE=Msc PUSCH-initial·Nsymb PUSCH-initial이다. Δ TF, C (i) = 10log 10 ((2 BPRE · Ks −1) · β PUSCH offset ), which is a parameter for reflecting the influence of the modulation and coding scheme (MCS). Here, K S is a parameter provided as deltaMCS-Enabled in the upper layer for each serving cell C. In transmission mode 2, which is a mode for transmit diversity, K S = 0. If only control information is transmitted through the PUSCH without UL-SCH data, BPRE = O CQI / N RE . In all other cases, BPRE =
Figure PCTKR2012007902-appb-I000012
to be. Here, C is the number of code blocks, K r is the size of the code block, O CQI is the number of CQI / PMI bits including the number of CRC bits, N RE is the number of determined resource elements. That is, NRE = M sc PUSCH-initialN symb PUSCH-initial .
만일 PUSCH를 통해 UL-SCH 데이터 없이 제어정보만이 전송되는 경우 βPUSCH offset=βCQI offset로 설정하고 그 이외의 경우는 항상 1로 설정한다. If only control information is transmitted without UL-SCH data through the PUSCH, β PUSCH offset = β CQI offset is set. Otherwise, it is always set to 1.
δPUSCH,C는 수정 값이다. 또한 서빙셀 c에 대한 DCI 포멧 0 또는 4 내에 존재하는 전송전력제어명령(TPC command) 또는 다른 단말들과 공동으로 부호화되어 전송되는 DCI 포맷 3/3A내의 TPC 명령을 참조하여 결정된다. DCI 포맷 3/3A는 순환반복검사(Cyclic Redundancy Check: CRC) 패리티(parity) 비트들이 TPC-PUSCH-RNTI 로 스크램블링 되어 있어 상기 RNTI 값이 할당된 단말들만이 확인 가능하다. 여기서 상기 RNTI(Radio Network Temporary Identifier)값은 임의의 단말이 다수의 서빙셀들로 구성된 경우, 상기 각 서빙셀을 구분하기 위해 서빙셀마다 서로 다른 TPC-PUSCH-RNTI값이 할당될 수 있다. 또는 송수신점들을 구분하기 위해 각 송수신점마다 서로 다른 TPC-PUSCH-RNTI값이 할당될 수도 있다. fc(i)는 현재 서빙셀 C에 대한 PUSCH 전력제어 조정 상태를 나타낸다. δ PUSCH, C is a correction value. In addition, it is determined by referring to a TPC command present in DCI format 0 or 4 for serving cell c or a TPC command in DCI format 3 / 3A that is encoded and transmitted jointly with other terminals. In DCI format 3 / 3A, cyclic cyclic redundancy check (CRC) parity bits are scrambled with TPC-PUSCH-RNTI, so only terminals assigned the RNTI value can be checked. In this case, when an arbitrary terminal is configured with a plurality of serving cells, a different TPC-PUSCH-RNTI value may be allocated to each serving cell to distinguish each serving cell. Alternatively, a different TPC-PUSCH-RNTI value may be assigned to each transmit / receive point to distinguish between the transmit and receive points. f c (i) indicates a PUSCH power control adjustment state for the serving cell C.
도 7에서는 부 송수신점이 2개인 것으로 가정하여 설명하였으나, 부 송수신점은 1개일 수도 있고, 2개 이상일 수도 있다. 부 송수신점은 1개일 경우 수학식 3, 4, 5에서의 연산에 의한 제i 경로 손실값과 제(i+1) 경로 손실값만으로도 상향링크 경로 손실값 PLC를 계산할 수 있으므로, 단계 S710에 따른 수학식 6, 수학식 7의 계산은 생략될 수 있다. In FIG. 7, it is assumed that there are two secondary transmission / reception points. However, one secondary transmission / reception point may be one or two or more. In the case of one secondary transmission / reception point, the uplink path loss value PL C can be calculated using only the i th path loss value and the (i + 1) th path loss value by the operation in Equations 3, 4, and 5, Calculations according to Equations 6 and 7 may be omitted.
협력 집합에 속하는 부 송수신점들의 기준신호 전송전력은 모두 동일할 수도 있다. 이 경우, 모든 부 송수신점들은 도 8과 같이 동일한 비전송 타이밍을 가질 수 있으며, 동일한 비전송 타이밍에서 뮤팅 모드로 동작할 수 있다. 매 뮤팅 주기마다 모든 부 송수신점이 1회의 비전송 타이밍만을 가진다. 즉 비전송 타이밍 제한을 줄일 수 있다. 모든 부 송수신점들의 오프셋 1로 동일하게 지정되므로, 단말은 오프셋을 알려주는 별도의 시그널링이 없이도, 상향링크 경로 손실값을 구할 수 있다. 즉, 시그널링의 부담도 줄일 수 있다. 또한 단말은 주 송수신점의 기준신호에 대한 경로 손실과 부 송수신점들의 기준신호에 대한 경로 손실을 나누어 계산할 수 있다. The reference signal transmission powers of the sub transceivers belonging to the cooperative set may all be the same. In this case, all the sub transmission and reception points may have the same non-transmission timing as shown in FIG. 8, and may operate in a muting mode at the same non-transmission timing. Every sub-transmission point has only one non-transmission timing in each muting period. That is, the non-transmission timing limit can be reduced. Since the offset 1 of all secondary transmission and reception points are equally designated, the UE can obtain an uplink path loss value without any separate signaling indicating the offset. That is, the burden of signaling can also be reduced. In addition, the terminal may calculate the path loss for the reference signal of the main transmission and reception points and the path loss of the reference signal of the secondary transmission and reception points.
도 9는 본 발명의 다른 예에 따른 단말이 상향링크 전력 손실값을 측정하는 동작을 설명하는 순서도이다. 이는 부 송신점들이 모두 동일한 전력으로 기준 신호를 전송하는 경우이며, 도 8과 같이 모든 부 송신점들의 비전송 타이밍은 PL 측정구간내에서 일치한다. 9 is a flowchart illustrating an operation of measuring an uplink power loss value by a terminal according to another embodiment of the present invention. This is a case where the sub transmission points all transmit the reference signal with the same power, and as shown in FIG. 8, non-transmission timing of all the sub transmission points coincides within the PL measurement interval.
도 9를 참조하면, 단말은 PL 측정구간에서 매 서브프레임마다 기준신호를 수신한다(S900). 모든 부 송수신점들이 뮤팅 모드인 서브프레임 #i에서 수신된 기준신호를 기반으로 제i 경로 손실값을 계산한다(S905). 제i 경로 손실값은 다음의 수학식에 의해 계산된다. 9, the terminal receives a reference signal every subframe in the PL measurement interval (S900). The i-th path loss value is calculated based on the reference signal received in subframe #i in which all sub-transmitting and receiving points are the muting mode (S905). The i th path loss value is calculated by the following equation.
수학식 10
Figure PCTKR2012007902-appb-M000010
 Equation 10
Figure PCTKR2012007902-appb-M000010
수학식 10을 참조하면, Li는 하향링크에 대한 제i 경로 손실값으로서 dB단위이다. LP는 주 송수신점의 기준신호에 대한 경로 손실값이다. 서브프레임 #i에서는 그룹 1에 속하는 주 송수신점만이 기준신호를 전송하므로, Li=LP이다. 기준신호의 전송전력(referenceSignalPower)은 상위계층에서 제공되며, 하향링크 기준신호의 자원요소당 에너지(Energy Per Resource Element: EPRE)값으로 dBm 단위이다. RSRP는 고려되는 측정 주파수 대역폭내의 기준신호를 운반하는 모든 자원요소들의 전력 기여들에 대한 선형 평균으로 정의된다. 즉 주 송수신점이 기준신호의 전송전력 값을 단말에게 알려주면, 단말은 기준신호 전송전력 값에서 실제 수신한 기준신호의 전력을 측정한 값을 뺌으로써 제i 경로 손실값을 얻을 수 있다. Referring to Equation 10, L i is the i-th path loss value for the downlink in dB unit. L P is a path loss value for the reference signal of the main transceiver point. In subframe #i, since only the main transmission / reception point belonging to group 1 transmits a reference signal, L i = L P. The reference signal power of the reference signal is provided by an upper layer, and is an energy per resource element (EPRE) value of a downlink reference signal in dBm units. RSRP is defined as the linear average over the power contributions of all resource elements carrying a reference signal within the measured frequency bandwidth under consideration. That is, when the main transceiver point informs the terminal of the transmission power value of the reference signal, the terminal may obtain the i-th path loss value by subtracting the measured value of the power of the reference signal actually received from the reference signal transmission power value.
다음으로, 단말은 모든 송수신점들이 기준신호를 전송하는 서브프레임 #(i+1)에서 수신된 기준신호를 기반으로 제(i+1) 경로 손실값을 계산한다(S910). 서브프레임 #(i+1)에서는 그룹 2에 속하는 모든 송수신점들이 기준신호를 전송하므로, 제(i+1) 경로 손실값은 다음의 수학식에 의해 계산된다. Next, the terminal calculates a (i + 1) th path loss value based on the reference signal received in subframe # (i + 1) in which all transmission and reception points transmit the reference signal (S910). In subframe # (i + 1), all transmission / reception points belonging to group 2 transmit a reference signal, and thus, the (i + 1) th path loss value is calculated by the following equation.
수학식 11
Figure PCTKR2012007902-appb-M000011
 Equation 11
Figure PCTKR2012007902-appb-M000011
수학식 11을 참조하면,
Figure PCTKR2012007902-appb-I000013
는 제(i+1) 경로 손실값이고, PP는 주 송수신점의 기준신호 전송전력이며, PS는 모든 부 송수신점의 기준신호 전송전력이고, LS1은 제1 부 송수신점의 기준신호에 대한 경로 손실값, LS2은 제2 부 송수신점의 기준신호에 대한 경로 손실값이다.
Figure PCTKR2012007902-appb-I000014
는 단말이 측정가능한 값이고, PP, PS는 모두 단말이 이미 알고 있는 값이며, LP는 수학식 10에서 구해진 값이다. 따라서, 단말은 제(i+1) 경로 손실값 LS1와 LS2의 비선형 합은 다음의 수학식과 같이 구할 수 있다. Referring to Equation 11,
Figure PCTKR2012007902-appb-I000013
Is the (i + 1) path loss value, P P is the reference signal transmission power of the main transmission / reception point, P S is the reference signal transmission power of all secondary transmission / reception points, and L S1 is the reference signal of the first secondary transmission / reception point. The path loss value for, L S2, is a path loss value for the reference signal of the second secondary transceiver point.
Figure PCTKR2012007902-appb-I000014
Is a value that can be measured by the terminal, P P and P S are values that the terminal already knows, and L P is a value obtained from Equation 10. Accordingly, the terminal may obtain the nonlinear sum of the (i + 1) th path loss values L S1 and L S2 as shown in the following equation.
수학식 12
Figure PCTKR2012007902-appb-M000012
 Equation 12
Figure PCTKR2012007902-appb-M000012
따라서, 단말은 상향링크 경로 손실값 PLC를 다음과 같은 수학식에 의해 구할 수 있다(S915). Therefore, the UE can obtain the uplink path loss value PL C by the following equation (S915).
수학식 13
Figure PCTKR2012007902-appb-M000013
 Equation 13
Figure PCTKR2012007902-appb-M000013
수학식 13을 참조하면, 상향링크 경로 손실값 PLC는 LP, LS1, LS2의 비선형 평균치로써 구해진다. 단말은 상향링크 경로 손실값 PLC를 이용하여 상향링크 전송 전력을 계산한다(S920). Referring to Equation 13, an uplink path loss PL value C is obtained as a non-linear mean value of P L, L S1, L S2. The UE calculates uplink transmission power using the uplink path loss value PL C (S920).
이하에서 기준신호 스케줄링 정보에 관하여 보다 상세히 개시한다. 기준신호 스케줄링 정보는 부 송수신점의 비전송 타이밍을 지시하는 비전송 타이밍 정보(non-Tx timing information), 부 송수신점의 기준신호 전송 전력에 관한 정보 및 협력 집합의 크기에 관한 정보 중 적어도 하나를 포함한다. Hereinafter, the reference signal scheduling information will be described in more detail. The reference signal scheduling information includes at least one of non-Tx timing information indicating non-transmission timing of the secondary transceiver point, information on the reference signal transmission power of the secondary transceiver point, and information on the size of the cooperative set. Include.
일 예로서, 비전송 타이밍 정보는 각 부송수신점의 기준신호의 비전송 타이밍을 뮤팅 주기와, 오프셋으로 정의한다. 이는 협력 집합에 속하는 각 부송수신점의 기준신호 전송전력이 다른 경우이다. PL 측정구간내에서 오프셋은 부 송수신점의 기준신호가 전송되는 시점을 나타낸다. 반대로, PL 측정 구간내에서 오프셋 이외의 타이밍에는 부 송수신점이 뮤팅 모드로 동작한다. 비전송 타이밍 정보는 협력 집합에 포함된 각 부송수신점마다 개별적으로 정의된다. 예를 들어 비전송 타이밍 정보는 다음의 표와 같이 4비트로 정의될 수 있다. As an example, the non-transmission timing information defines the non-transmission timing of the reference signal of each sub-reception point as a muting period and an offset. This is a case where the reference signal transmission power of each sub-reception point belonging to the cooperative set is different. Within the PL measurement interval, the offset indicates the point in time at which the reference signal of the sub transmission / reception point is transmitted. On the contrary, the sub transmission / reception points operate in the muting mode at timings other than the offset within the PL measurement period. Non-transmission timing information is defined individually for each sub-reception point included in the cooperative set. For example, non-transmission timing information may be defined as 4 bits as shown in the following table.
표 2
비전송 타이밍 정보비트 뮤팅 주기(ms) 오프셋
0000 5 mod(1,N)
0001 5 mod(2,N)
0010 5 mod(3,N)
0011 5 mod(4,N)
0100 10 mod(1,N)
0101 10 mod(2,N)
0110 10 mod(3,N)
0111 10 mod(4,N)
1000 20 mod(1,N)
1001 20 mod(2,N)
1010 20 mod(3,N)
1011 20 mod(4,N)
1100 40 mod(1,N)
1101 40 mod(2,N)
1110 40 mod(3,N)
1111 40 mod(4,N)
TABLE 2
Non-transmission timing information bit Muting cycle (ms) offset
0000 5 mod (1, N)
0001 5 mod (2, N)
0010 5 mod (3, N)
0011 5 mod (4, N)
0100 10 mod (1, N)
0101 10 mod (2, N)
0110 10 mod (3, N)
0111 10 mod (4, N)
1000 20 mod (1, N)
1001 20 mod (2, N)
1010 20 mod (3, N)
1011 20 mod (4, N)
1100 40 mod (1, N)
1101 40 mod (2, N)
1110 40 mod (3, N)
1111 40 mod (4, N)
표 2를 참조하면, N은 PL 측정구간의 길이(서브프레임의 개수)이다. 또는, N은 협력 집합의 크기, 즉 협력 집합에 포함되는 송수신점의 개수를 의미할 수도 있다. 예를 들어, N=4이고 특정 부송수신점의 기준신호 스케줄링 정보가 1010이면, 상기 특정 부송수신점의 뮤팅 주기는 20ms이고, 오프셋은 mod(3,4)=3ms이다. 따라서, 상기 특정 부송수신점이 PL 측정구간내에서 기준신호를 전송하는 타이밍은 20ms(뮤팅 주기)+3ms(오프셋)=23ms이다. 예를 들어, 23ms에서 상기 특정 송수신점은 기준신호를 전송하고, 20ms, 21ms, 22ms에서 상기 특정 부송수신점이 뮤팅 모드로 동작한다. Referring to Table 2, N is the length (number of subframes) of the PL measurement interval. Alternatively, N may mean the size of the cooperative set, that is, the number of transmission and reception points included in the cooperative set. For example, when N = 4 and reference signal scheduling information of a specific CC is 1010, the muting period of the specific CC is 20ms, and an offset is mod (3,4) = 3ms. Accordingly, the timing of transmitting the reference signal within the PL measurement point is 20 ms (muting period) + 3 ms (offset) = 23 ms. For example, at 23ms, the specific transmission / reception point transmits a reference signal, and at 20ms, 21ms, and 22ms, the specific sub-reception point operates in a muting mode.
다른 예로서, 비전송 타이밍 정보는 각 부송수신점의 기준신호의 비전송 타이밍을 뮤팅 주기로써 정의한다. 이는 협력 집합에 속하는 각 부송수신점의 기준신호 전송전력이 동일한 경우이다. PL 측정 구간내에서 매 뮤팅 주기가 끝나는 시점 또는 시작하는 시점에서 부 송수신점이 뮤팅 모드로 동작한다. 비전송 타이밍 정보는 협력 집합에 포함된 각 부송수신점마다 개별적으로 정의된다. 예를 들어 비전송 타이밍 정보는 다음의 표와 같이 2비트로 정의될 수 있다.As another example, the non-transmission timing information defines the non-transmission timing of the reference signal of each sub-reception point as a muting period. This is the case where the reference signal transmission power of each sub-reception point belonging to the cooperative set is the same. The sub transmission / reception point operates in the muting mode at the end of each muting period or at the beginning of the PL measurement interval. Non-transmission timing information is defined individually for each sub-reception point included in the cooperative set. For example, the non-transmission timing information may be defined as 2 bits as shown in the following table.
표 3
비전송 타이밍 정보비트 뮤팅 주기
00 5ms
01 10ms
10 20ms
11 40ms
TABLE 3
Non-Transmission Timing Information Bit Muting cycle
00 5 ms
01 10 ms
10 20 ms
11 40 ms
표 3을 참조하면, 예를 들어 특정 부송수신점의 기준신호 스케줄링 정보가 10이면, 특정 부송수신점의 뮤팅 주기는 20ms이다. 따라서, 상기 특정 부송수신점은 매 20ms마다 뮤팅 모드로 동작한다. Referring to Table 3, for example, if reference signal scheduling information of a specific CC is 10, the muting period of the specific CC is 20 ms. Therefore, the specific sub-reception point operates in a muting mode every 20 ms.
이와 같이 기준신호 스케줄링 정보는 협력 집합에 속하는 각 부송신점들의 기준신호 전송을 제한하거나 제어함으로써, PL 측정구간 동안에는 단말이 특정 송수신점의 기준신호만을 선택적으로 수신할 수 있도록 한다. As such, the reference signal scheduling information restricts or controls the transmission of the reference signal of each sub-transmission point belonging to the cooperative set, so that the terminal can selectively receive only the reference signal of the specific transmission / reception point during the PL measurement interval.
도 10은 본 발명의 일 예에 따른 부 송수신점이 PL 측정구간에서 기준신호의 전송을 제어하는 방법을 나타내는 순서도이다.10 is a flowchart illustrating a method of controlling a transmission of a reference signal in a PL measurement section by a sub transceiver according to an example of the present invention.
도 10을 참조하면, 부 송수신점은 주 송수신점으로부터 기준신호 스케줄링을 수신한다(S1000). 이때, 부 송수신점은, 기준신호 스케줄링에 관한 정보를 단말로 전달해줄 수 있다(도면에 미도시). 부 송수신점은 기준신호 스케줄링에 따라 비전송 타이밍을 설정한다(S1005). 비전송 타이밍은 PL 측정구간에 존재하며, 주기적으로 반복된다. 비전송 타이밍은 뮤팅 주기와 오프셋으로 정의되거나, 뮤팅 주기만으로 정의된다. Referring to FIG. 10, the secondary transmission / reception point receives reference signal scheduling from the primary transmission / reception point (S1000). At this time, the secondary transmission and reception point, may transmit the information about the reference signal scheduling to the terminal (not shown in the figure). The secondary transmission / reception point sets non-transmission timing according to the reference signal scheduling (S1005). Non-transmission timing is present in the PL measurement interval and is repeated periodically. Non-transmission timing is defined by a muting period and an offset, or by a muting period only.
부 송수신점은 상기 기준신호 스케줄링에 기반하여, 현재 서브프레임이 PL 측정구간의 비전송 타이밍인지 판단한다(S1010). 만약 현재 서브프레임이 비전송 타이밍이면, 부 송수신점은 뮤팅 모드로 동작한다(S1015). 만약 현재 서브프레임이 비전송 타이밍이 아니면, 부 송수신점은 기준신호를 단말로 전송한다(S1020). 기준신호를 셀 특정 기준신호(CRS)를 포함한다. 부 송수신점은 단말로부터 상향링크 신호를 수신한다(S1025). 상향링크 신호는 PUSCH 또는 PUCCH와 같은 물리채널을 포함한다. 상향링크 신호는 단말이 결정한 상향링크 전송전력으로 전송되며, 상향링크 전송전력은 상기 기준신호와 비전송 타이밍에 기반하여 결정된 상향링크 경로 손실값에 기반하여 결정된다. The secondary transmission / reception point determines whether the current subframe is a non-transmission timing of the PL measurement interval based on the reference signal scheduling (S1010). If the current subframe is non-transmission timing, the secondary transmission and reception point operates in the muting mode (S1015). If the current subframe is not the non-transmission timing, the secondary transmission and reception point transmits a reference signal to the terminal (S1020). The reference signal includes a cell specific reference signal (CRS). The secondary transmission / reception point receives an uplink signal from the terminal (S1025). The uplink signal includes a physical channel such as a PUSCH or a PUCCH. The uplink signal is transmitted using the uplink transmission power determined by the terminal, and the uplink transmission power is determined based on the uplink path loss value determined based on the reference signal and the non-transmission timing.
도 11은 본 발명에 따라 상향링크 전송전력을 제어하는 시나리오의 일 예이다.11 is an example of a scenario of controlling uplink transmission power according to the present invention.
도 11을 참조하면, 주 송수신점인 매크로 기지국(eNodeB, 1100)과 부 송수신점인 RRH(1105)가 하나의 협력 집합을 구성하고, 단말(UE, 1110)과 CoMP 방식으로 통신을 수행한다. 이는 하향링크 신호를 전송하는 전송점과, 상향링크 신호를 수신하는 수신점이 다른 경우이다. 즉, 전송점은 매크로 기지국(1100)이고, 수신점은 RRH(1105)이다. 예를 들어 저전력 RRH는 매크로 기지국보다 전송전력이 작아 하향링크 커버리지(coverage)가 작지만 상향링크의 경우는 상향링크 전력손실이 작은 RRH가 선택될 수 있다. Referring to FIG. 11, a macro base station (eNodeB) 1100 serving as a main transmission / reception point and an RRH 1105 serving as a secondary transmission / reception point form one cooperative set and communicate with a UE UE 1110 in a CoMP scheme. This is a case where a transmission point for transmitting a downlink signal and a reception point for receiving an uplink signal are different. That is, the transmission point is the macro base station 1100 and the reception point is the RRH 1105. For example, a low power RRH may have a smaller transmission power than a macro base station, so that downlink coverage is small, but in the case of uplink, an RRH having a small uplink power loss may be selected.
매크로 기지국(1100)은 단말(1110)로 하향링크 신호를 전송하며, 이때 하향링크 경로 손실(PL_DL)이 발생한다. 그리고 단말(1110)은 RRH(1105)로 상향링크 신호를 전송하며, 이때 상향링크 경로 손실(PL_UL)이 발생한다. 단말이 상기 상향링크 경로 손실(PL_UL)을 구하기 위해 상기 하향링크 경로 손실(PL_DL)를 이용하는 경우, 경로 자체가 다르므로 정확한 상기 상향링크 경로 손실(PL_UL)은 정확하지 않다. 또는 협력다중통신 시나리오 4에서는 단말이 상기 상향링크 경로 손실(PL_UL)을 구하기 위해 RRH(1105)로부터 CRS를 수신하는 경우, 매크로 기지국(1100)이 동일한 CRS를 전송하기 때문에 단말은 2개의 CRS를 구별할 수 없다. 따라서 상기 상향링크 경로 손실(PL_UL)이 정확히 계산될 수 없다. 그러나, 본 발명에 따르면, RRH(1105)가 특정 비전송 타이밍에 뮤팅 모드로 동작하기 때문에, 상기 비전송 타이밍에 매크로 기지국(1100)에 대한 상향링크 경로 손실을 구할 수 있고, 상기 비전송 타이밍을 제외한 시점에 RRH(1105)에 대한 상기 상향링크 경로 손실(PL_UL)을 구할 수 있다. The macro base station 1100 transmits a downlink signal to the terminal 1110, where a downlink path loss (PL_DL) occurs. The terminal 1110 transmits an uplink signal to the RRH 1105, where an uplink path loss (PL_UL) occurs. When the terminal uses the downlink path loss (PL_DL) to obtain the uplink path loss (PL_UL), since the path itself is different, the correct uplink path loss (PL_UL) is not accurate. Alternatively, in the cooperative multiple communication scenario 4, when the terminal receives the CRS from the RRH 1105 to obtain the uplink path loss (PL_UL), the terminal distinguishes two CRSs because the macro base station 1100 transmits the same CRS. Can not. Therefore, the uplink path loss PL_UL cannot be accurately calculated. However, according to the present invention, since the RRH 1105 operates in a muting mode at a specific non-transmission timing, an uplink path loss for the macro base station 1100 can be obtained at the non-transmission timing, and the non-transmission timing is determined. The uplink path loss PL_UL for the RRH 1105 may be obtained at the excluded time point.
도 12는 본 발명에 따라 상향링크 전송전력을 제어하는 시나리오의 다른 예이다.12 is another example of a scenario of controlling uplink transmission power according to the present invention.
도 12를 참조하면, 주 송수신점인 매크로 기지국(eNodeB, 1200)과 부 송수신점인 RRH(1205)가 하나의 협력 집합을 구성하고, 단말(UE, 1210)과 CoMP 방식으로 통신을 수행한다. 이는 하향링크 신호를 전송하는 전송점과, 상향링크 신호를 수신하는 수신점이 일부 동일한 경우이다. 즉, 전송점은 매크로 기지국(1200)이고, 수신점은 매크로 기지국(1200)과 RRH(1205)이다.Referring to FIG. 12, a macro base station (eNodeB) 1200 that is a main transmission / reception point and an RRH 1205 that is a secondary transmission / reception point form one cooperative set, and communicate with a UE UE 1210 in a CoMP scheme. This is a case where a transmission point for transmitting a downlink signal and a reception point for receiving an uplink signal are partially the same. That is, the transmission point is the macro base station 1200 and the receiving point is the macro base station 1200 and the RRH 1205.
매크로 기지국(1200)은 단말(1210)로 하향링크 신호를 전송하며, 이때 하향링크 경로 손실(PL_DL)이 발생한다. 그리고 단말(1210)은 매크로 기지국(1200)과 RRH(1205)로 상향링크 신호를 전송하며, 이때 각각 제1 상향링크 경로 손실(PL_UL1)과 제2 상향링크 경로 손실(PL_UL2)이 발생한다. The macro base station 1200 transmits a downlink signal to the terminal 1210, where a downlink path loss (PL_DL) occurs. The terminal 1210 transmits an uplink signal to the macro base station 1200 and the RRH 1205, where a first uplink path loss PL_UL1 and a second uplink path loss PL_UL2 occur, respectively.
단말(1210)이 상기 제1 상향링크 경로 손실(PL_UL1)을 구하려면, 먼저 매크로 기지국(1200)으로부터 CRS를 수신하여야 한다. 그런데, 협력다중통신 시나리오 4에서는 RRH(1205)도 동일한 CRS를 단말(1210)로 전송하므로, 단말(1210)은 정확한 제1 상향링크 경로 손실(PL_UL1)을 구할 수 없다. 이는 제2 상향링크 경로 손실(PL_UL1)에 대해서도 마찬가지이다. 그러나, 본 발명에 따르면, RRH(1205)가 특정 비전송 타이밍에 뮤팅 모드로 동작하기 때문에, 상기 비전송 타이밍에 매크로 기지국(1200)에 대한 제1 상향링크 경로 손실(PL_UL1)을 구할 수 있고, 상기 비전송 타이밍을 제외한 시점에 RRH(1205)에 대한 제2 상기 상향링크 경로 손실(PL_UL2)을 구할 수 있다. In order for the terminal 1210 to obtain the first uplink path loss PL_UL1, it must first receive a CRS from the macro base station 1200. However, in the cooperative multiple communication scenario 4, since the RRH 1205 also transmits the same CRS to the terminal 1210, the terminal 1210 cannot obtain an accurate first uplink path loss PL_UL1. The same applies to the second uplink path loss PL_UL1. However, according to the present invention, since the RRH 1205 operates in the muting mode at a specific non-transmission timing, the first uplink path loss PL_UL1 for the macro base station 1200 can be obtained at the non-transmission timing. The second uplink path loss PL_UL2 for the RRH 1205 may be obtained at a time other than the non-transmission timing.
도 13은 본 발명에 따라 상향링크 전송전력을 제어하는 시나리오의 또 다른 예이다.13 is another example of a scenario of controlling uplink transmission power according to the present invention.
도 13을 참조하면, 주 송수신점인 매크로 기지국(eNodeB, 1300)과 부 송수신점인 RRH1(1305), RRH2(1310)가 하나의 협력 집합을 구성하고, 단말(UE, 1315)과 CoMP 방식으로 통신을 수행한다. 이는 하향링크 신호를 전송하는 전송점과, 상향링크 신호를 수신하는 수신점이 동일한 경우이다. 즉, 전송점은 매크로 기지국(1300), RRH1(1305), RRH2(1310)이고, 수신점도 매크로 기지국(1300), RRH1(1305), RRH2(1310)이다.Referring to FIG. 13, a macro base station (eNodeB) 1300 serving as a main transmission / reception point, and an RRH1 1305 and an RRH2 1310 serving as a secondary transmission / reception point form one cooperative set, and the UE (UE) 1315 may use a CoMP scheme. Perform communication. This is the case where a transmission point for transmitting a downlink signal and a reception point for receiving an uplink signal are the same. That is, the transmission points are the macro base station 1300, RRH1 1305, and RRH2 1310, and the reception point is the macro base station 1300, RRH1 1305, and RRH2 1310.
매크로 기지국(1300), RRH1(1305), RRH2(1310)는 각각 단말(1210)로 하향링크 신호를 전송하며, 각각에 대해 제1 하향링크 경로 손실(PL_DL1), 제2 하향링크 경로 손실(PL_DL2), 제3 하향링크 경로 손실(PL_DL3)이 발생한다. 그리고 단말(1210)은 매크로 기지국(1300), RRH1(1305), RRH2(1310)로 상향링크 신호를 전송하며, 이때 각각에 대해 제1 상향링크 경로 손실(PL_UL1), 제2 상향링크 경로 손실(PL_UL2), 제3 상향링크 경로 손실(PL_UL3)이 발생한다. The macro base station 1300, the RRH1 1305, and the RRH2 1310 transmit downlink signals to the terminal 1210, respectively, and each of the first downlink path loss (PL_DL1) and the second downlink path loss (PL_DL2) ), A third downlink path loss PL_DL3 occurs. The terminal 1210 transmits an uplink signal to the macro base station 1300, the RRH1 1305, and the RRH2 1310, and at this time, a first uplink path loss (PL_UL1) and a second uplink path loss (for each). PL_UL2) and a third uplink path loss PL_UL3.
본 발명에 따르면, RRH1(1305)과 RRH2(1310)가 제1 비전송 타이밍에 뮤팅 모드로 동작하고, RRH2(1310)가 제2 비전송 타이밍에 뮤팅 모드로 동작하며, RRH1(1305)이 제3 비전송 타이밍에 뮤팅 모드로 동작한다. 단말(1315)은 제1 비전송 타이밍에 매크로 기지국(1300)에 대한 제1 상향링크 경로 손실(PL_UL1)을 구할 수 있고, 제2 비전송 타이밍에 RRH1(1305)에 대한 제2 상향링크 경로 손실(PL_UL2)을 구할 수 있으며, 제3 비전송 타이밍에 RRH2(1310)에 대한 제3 상향링크 경로 손실(PL_UL3)을 구할 수 있다. According to the present invention, the RRH1 1305 and the RRH2 1310 operate in a muting mode at the first non-transmission timing, the RRH2 1310 operate in a muting mode at the second non-transmission timing, and the RRH1 1305 operates in the muting mode. 3 Operates in muting mode at non-transmission timing. The UE 1315 may obtain the first uplink path loss PL_UL1 for the macro base station 1300 at the first non-transmission timing, and the second uplink path loss for the RRH1 1305 at the second non-transmission timing. (PL_UL2) can be obtained, and the third uplink path loss (PL_UL3) for the RRH2 1310 can be obtained at the third non-transmission timing.
도 14는 본 발명의 일 예에 따른 단말과 송수신점을 도시한 블록도이다.14 is a block diagram illustrating a terminal and a transmission and reception point according to an embodiment of the present invention.
도 14를 참조하면, 단말(1400)은 단말 RF부(1405) 및 단말 프로세서(1410)를 포함한다. 단말 프로세서(1410)는 단말 메시지 처리부(1411) 및 전송 전력 제어부(1412)를 포함한다. Referring to FIG. 14, the terminal 1400 includes a terminal RF unit 1405 and a terminal processor 1410. The terminal processor 1410 includes a terminal message processor 1411 and a transmission power controller 1412.
단말 RF부(1405)는 주 송수신점(1480)으로부터 기준신호(RS) 스케줄링 정보를 수신하고, 송수신점(1450)으로부터 기준신호를 수신하며, 송수신점(1450)으로 상향링크 신호를 전송한다. 송수신점(1450)은 부 송수신점일 수 있다. The terminal RF unit 1405 receives reference signal (RS) scheduling information from the main transmission / reception point 1480, receives a reference signal from the transmission / reception point 1450, and transmits an uplink signal to the transmission / reception point 1450. The transceiver point 1450 may be a secondary transceiver point.
단말 메시지 처리부(1411)는 RS 스케줄링 정보에 포함된 정보를 분석하여, 송수신점(1450)의 비전송 타이밍 정보를 획득하고, 비전송 타이밍 정보를 전송 전력 제어부(1412)로 전달한다. The terminal message processor 1411 analyzes the information included in the RS scheduling information, obtains non-transmission timing information of the transmission / reception point 1450, and transmits the non-transmission timing information to the transmission power control unit 1412.
전송 전력 제어부(1412)는 도 7 또는 도 9와 같은 동작 흐름도에 따라 상향링크 경로 손실값을 구할 수 있다. 예를 들어, 전송 전력 제어부(1412)는 송수신점(1450)의 비전송 타이밍에서 발생하는 제1 하향링크 경로 손실값과, 송수신점(1450)의 전송 타이밍에서 발생하는 제2 하향링크 경로 손실값을 구한다. 그리고 전송 전력 제어부(1412)는 제1 하향링크 경로 손실값에서 제1 상향링크 경로 손실값을 추정하고, 상기 송수신점(1450)의 기준신호 전송전력값과 상기 제1 상향링크 경로 손실값, 그리고 상기 제1 하향링크 경로 손실값에서 제2 상향링크 경로 손실값을 구한다. 그리고 전송 전력 제어부(1412)는 제1 및 제2 상향링크 경로 손실값들에 대해 비선형 평균치를 취하여 최종 상향링크 경로 손실값으로 결정한다. The transmit power controller 1412 may obtain an uplink path loss value according to the operation flowchart of FIG. 7 or 9. For example, the transmission power control unit 1412 may include a first downlink path loss value generated at the non-transmission timing of the transmission / reception point 1450 and a second downlink path loss value generated at the transmission timing of the transmission / reception point 1450. Obtain The transmit power controller 1412 estimates a first uplink path loss value from a first downlink path loss value, a reference signal transmit power value of the transceiver point 1450, the first uplink path loss value, and A second uplink path loss value is obtained from the first downlink path loss value. The transmission power controller 1412 determines a final uplink path loss value by taking a non-linear average value of the first and second uplink path loss values.
전송 전력 제어부(1412)는 최종 상향링크 경로 손실값을 수학식 8과 같이 상향링크 전송전력 값을 구하는 식에 대입하여 상향링크 전송전력을 계산한다. The transmit power controller 1412 calculates the uplink transmit power by substituting the final uplink path loss value into an equation for obtaining the uplink transmit power value as shown in Equation (8).
단말 RF부(1405)는 전송 전력 제어부(1412)에 의해 구해진 상향링크 전송전력으로 상향링크 신호를 송수신점(1450)으로 전송한다. The terminal RF unit 1405 transmits an uplink signal to the transceiver point 1450 using the uplink transmission power obtained by the transmission power control unit 1412.
송수신점(1450)은 송수신점 RF부(1455) 및 송수신점 프로세서(1460)를 포함한다. 송수신점 프로세서(1460)는 송수신점 메시지 처리부(1461) 및 RS 전송 제어부(1462)를 포함한다. The transceiver point 1450 includes a transceiver point RF unit 1455 and a transceiver point processor 1460. The transmit / receive point processor 1460 includes a transmit / receive point message processor 1462 and an RS transmission controller 1462.
송수신점 RF부(1455)는 비전송 타이밍에 기반하여, 기준신호를 단말(1400)로 전송한다. 그리고 송수신점 RF부(1455)는 특정한 수준의 송신전력으로 전송된 상향링크 신호를 단말(1400)로부터 수신하고, 주 송수신점(1480)으로부터 RS 스케줄링 정보를 수신한다. The transceiver point RF unit 1455 transmits a reference signal to the terminal 1400 based on the non-transmission timing. The transceiver point RF unit 1455 receives an uplink signal transmitted at a specific level of transmission power from the terminal 1400, and receives RS scheduling information from the primary transceiver point 1480.
송수신점 메시지 처리부(1461)는 수신된 상향링크 신호 또는 RS 스케줄링 정보를 해석하여, 상향링크 신호에 따른 동작을 수행하거나, 송수신점(1450)에 고유한 비전송 타이밍 정보를 추출하여 RS 전송 제어부(1462)로 전달하거나, 상위계층의 메시지를 생성한다. The transceiver message processor 1541 may analyze the received uplink signal or RS scheduling information, perform an operation according to the uplink signal, or extract non-transmission timing information unique to the transceiver point 1450 to generate an RS transmission controller ( 1462) or a higher layer message.
RS 전송 제어부(1462)는 송수신점(1450)의 기준신호 전송을 제어한다. 예를 들어, RS 전송 제어부(1462)는 비전송 타이밍에 송수신점(1450)을 뮤팅 모드로 동작하도록 제어한다. 뮤팅 모드는 RS 전송 제어부(1462)가 기준신호를 영전력으로 설정하는 모드이다. RS 전송 제어부(1462)는 비전송 타이밍을 제외한 다른 시점에는 송수신점 RF부(1455)가 기준신호를 전송하도록 제어하고, 비전송 타이밍에는 송수신점 RF부(1455)가 기준신호를 전송하지 않도록 제어한다. The RS transmission control unit 1462 controls the transmission of the reference signal of the transmission / reception point 1450. For example, the RS transmission controller 1462 controls the transmission / reception point 1450 to operate in a muting mode at non-transmission timing. The muting mode is a mode in which the RS transmission control unit 1462 sets the reference signal to zero power. The RS transmission control unit 1462 controls the transmission / reception point RF unit 1455 to transmit the reference signal at other times except for the non-transmission timing, and controls the transmission / reception point RF unit 1455 not to transmit the reference signal at non-transmission timing. do.
이상의 설명은 본 발명의 기술 사상을 예시적으로 설명한 것에 불과한 것으로서, 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자라면 본 발명의 본질적인 특성에서 벗어나지 않는 범위에서 다양한 수정 및 변형이 가능할 것이다. 따라서, 본 발명에 개시된 실시 예들은 본 발명의 기술 사상을 한정하기 위한 것이 아니라 설명하기 위한 것이고, 이러한 실시 예에 의하여 본 발명의 기술 사상의 범위가 한정되는 것은 아니다. 본 발명의 보호 범위는 아래의 청구범위에 의하여 해석되어야 하며, 그와 동등한 범위 내에 있는 모든 기술 사상은 본 발명의 권리범위에 포함되는 것으로 해석되어야 할 것이다. The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited thereto. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims (19)

  1. 단말에 의해 수행되는 상향링크 전송 전력의 제어방법에 있어서, In the control method of the uplink transmission power performed by the terminal,
    협력적 다중점(coordinated multiple points) 송수신 방식으로 동작하는 제1 그룹(group)의 송수신점(TX/RX point)들로부터 셀 특정 기준신호(cell specific reference signal: CRS)를 수신하는 제1 타이밍에, 제1 하향링크 경로 손실(path loss: PL)을 계산하는 단계;At a first timing of receiving a cell specific reference signal (CRS) from TX / RX points of a first group operating in a coordinated multiple point transmission / reception scheme. Calculating a first downlink path loss (PL);
    상기 제1 그룹과 다른 제2 그룹의 송수신점들로부터 셀 특정 기준신호를 수신하는 제2 타이밍에, 제2 하향링크 경로 손실을 계산하는 단계;Calculating a second downlink path loss at a second timing of receiving a cell specific reference signal from transmission / reception points of a second group different from the first group;
    상기 제1 및 제2 하향링크 경로 손실을 이용하여 상기 제1 및 제2 그룹의 모든 송수신점에 대한 하향링크 경로 손실을 개별적으로 계산하는 단계;Separately calculating downlink path loss for all transmission / reception points of the first and second groups using the first and second downlink path loss;
    상기 개별적으로 계산된 하향링크 경로 손실들의 비선형 평균치로써, 상향링크 경로 손실을 계산하는 단계;Calculating an uplink path loss as the non-linear average of the individually calculated downlink path losses;
    상기 상향링크 경로 손실을 기반으로 상향링크 전송 전력을 계산하는 단계; 및Calculating uplink transmission power based on the uplink path loss; And
    상향링크 신호를 상기 상향링크 전송 전력에 따라 전송하는 단계를 포함함을 특징으로 하는, 상향링크 전송 전력의 제어방법. And transmitting an uplink signal according to the uplink transmission power.
  2. 제 1 항에 있어서, The method of claim 1,
    상기 제2 타이밍은 일정한 주기와 오프셋(offset)으로 정의됨을 특징으로 하는, 상향링크 전송 전력의 제어방법. And wherein the second timing is defined by a constant period and an offset.
  3. 제 2 항에 있어서,The method of claim 2,
    상기 일정한 주기와 상기 오프셋에 관한 정보를 수신하는 단계를 더 포함함을 특징으로 하는, 상향링크 전송 전력의 제어방법.And receiving information regarding the constant period and the offset.
  4. 제 1 항에 있어서,The method of claim 1,
    상기 제1 그룹 또는 상기 제2 그룹은 주(primary) 송수신점과 부(secondary) 송수신점 중 적어도 하나를 포함하되, 상기 주 송수신점은 매크로 기지국(macro eNB)이고, 상기 부 송수신점은 원격 무선 헤드(remote radio head: RRH)임을 특징으로 하는, 상향링크 전송 전력의 제어방법.The first group or the second group includes at least one of a primary transceiver point and a secondary transceiver point, wherein the primary transceiver point is a macro eNB and the secondary transceiver point is a remote radio. And a remote radio head (RRH).
  5. 제 1 항에 있어서,The method of claim 1,
    상기 제2 타이밍에, 상기 셀 특정 기준신호는 영 전력(zero-power)로 설정됨을 특징으로 하는, 상향링크 전송 전력의 제어방법.And at the second timing, the cell specific reference signal is set to zero-power.
  6. 상향링크 전송 전력을 제어하는 단말에 있어서, In the terminal for controlling the uplink transmission power,
    협력적 다중점 송수신 방식으로 동작하는 제1 그룹의 송수신점들로부터 제1 타이밍에 제1 셀 특정 기준신호(CRS)를 수신하고, 상기 제1 그룹과 다른 제2 그룹의 송수신점들로부터 제2 타이밍에 제2 셀 특정 기준신호를 수신하는 RF부; 및Receiving a first cell specific reference signal (CRS) at a first timing from a first group of transmit / receive points operating in a cooperative multi-point transmit / receive scheme, and receiving a second cell from a second group of transmit / receive points different from the first group An RF unit configured to receive a second cell specific reference signal at a timing; And
    상기 제1 타이밍에 제1 하향링크 경로 손실을 계산하고, 상기 제2 타이밍에 제2 하향링크 경로 손실을 계산하며, 상기 제1 및 제2 하향링크 경로 손실을 이용하여 상기 제1 및 제2 그룹의 모든 송수신점에 대한 하향링크 경로 손실을 개별적으로 계산하고, 상기 개별적으로 계산된 하향링크 경로 손실들의 비선형 평균치로써 상향링크 경로 손실을 계산하며, 상기 상향링크 경로 손실을 기반으로 상향링크 전송 전력을 계산하는 전송 전력 제어부를 포함하되,Computing a first downlink path loss at the first timing, a second downlink path loss at the second timing, and using the first and second downlink path losses, the first and second groups. Compute downlink path loss for all transmission / reception points separately, calculate uplink path loss as the non-linear average of the individually calculated downlink path losses, and calculate uplink transmission power based on the uplink path loss. Including a transmission power control unit for calculating,
    상기 RF부는 상향링크 신호를 상기 상향링크 전송 전력에 따라 전송하는 것을 특징으로 하는, 단말. The RF unit, characterized in that for transmitting an uplink signal according to the uplink transmission power.
  7. 제 6 항에 있어서, The method of claim 6,
    상기 RF부는 일정한 주기와 오프셋(offset)으로 정의되는 상기 제2 타이밍에 상기 제2 셀 특정 기준신호를 수신함을 특징으로 하는, 단말. The RF unit is characterized in that for receiving the second cell specific reference signal at the second timing defined by a constant period and an offset.
  8. 제 7 항에 있어서,The method of claim 7, wherein
    상기 RF부는 상기 일정한 주기와 상기 오프셋에 관한 정보를 수신하고,The RF unit receives the information about the constant period and the offset,
    상기 일정한 주기와 상기 오프셋에 관한 정보를 처리하는 메시지 처리부를 더 포함함을 특징으로 하는, 단말.The terminal further comprises a message processing unit for processing the information about the fixed period and the offset.
  9. 제 6 항에 있어서,The method of claim 6,
    상기 제1 그룹 또는 상기 제2 그룹은 주 송수신점과 부 송수신점 중 적어도 하나를 포함하되, 상기 주 송수신점은 매크로 기지국이고, 상기 부 송수신점은 원격 무선 헤드임을 특징으로 하는, 단말.The first group or the second group includes at least one of a primary transmission point and a secondary transmission point, the primary transmission point and the macro base station, characterized in that the secondary transmission and reception point is a remote radio head, the terminal.
  10. 제 6 항에 있어서,The method of claim 6,
    상기 제2 타이밍에, 상기 셀 특정 기준신호는 영 전력로 설정됨을 특징으로 하는, 단말.And wherein the cell specific reference signal is set to zero power at the second timing.
  11. 원격 무선 헤드에 의해 수행되는 상향링크 전송 전력의 제어방법에 있어서, In the control method of the uplink transmission power performed by the remote radio head,
    단말이 상기 원격 무선 헤드에 대한 상향링크 경로 손실(pathloss: PL) 값을 측정하는데 사용되는 PL 측정 구간 내에서, 비전송 타이밍에 뮤팅 모드로 동작하는 단계;A terminal operating in a muting mode at non-transmission timing within a PL measurement interval used to measure an uplink pathloss (PL) value for the remote radio head;
    상기 PL 측정구간 내에서, 상기 비전송 타이밍 이외의 타이밍에 셀 특정 기준 신호를 상기 단말로 전송하는 단계; 및Transmitting a cell specific reference signal to the terminal at a timing other than the non-transmission timing within the PL measurement interval; And
    상기 PL 측정 구간에서 계산된 상향링크 경로 손실값에 기반한 상향링크 전송 전력으로 전송된 상향링크 신호를 상기 단말로부터 수신하는 단계를 포함함을 특징으로 하는, 상향링크 전송 전력의 제어방법. And receiving from the terminal an uplink signal transmitted with an uplink transmission power based on an uplink path loss value calculated in the PL measurement interval.
  12. 제 11 항에 있어서, 상기 비전송 타이밍은,The method of claim 11, wherein the non-transmission timing,
    상기 셀 특정 기준 신호의 전송전력정보 및 상기 셀 측정 기준 신호가 영 전력이 되는 주기로서 정의되거나, 또는 상기 전송전력정보와, 상기 주기 및 상기 주기내에서 셀 특정 기준 신호가 영 전력이 되지 않는 시점을 지시하는 오프셋으로서 정의됨을 특징으로 하는, 상향링크 전송 전력의 제어방법. When the transmission power information of the cell specific reference signal and the cell measurement reference signal are defined as a period of zero power, or when the transmission power information and the cell specific reference signal do not become zero power within the period and the period And an offset indicating an uplink transmission power.
  13. 제 11 항에 있어서, The method of claim 11,
    서로 다른 원격 무선 헤드들에는 상기 PL 측정구간 내에서 서로 다른 비전송 타이밍이 지정됨을 특징으로 하는, 상향링크 전송 전력의 제어방법. And different non-transmission timings are assigned to different remote radio heads within the PL measurement interval.
  14. 제 13 항에 있어서,The method of claim 13,
    상기 서로 다른 원격 무선 헤드들은 서로 다른 전력으로 셀 특정 기준 신호를 전송함을 특징으로 하는, 상향링크 전송 전력의 제어방법. And different remote radio heads transmit cell-specific reference signals at different powers.
  15. 제 11 항에 있어서,The method of claim 11,
    서로 다른 원격 무선 헤드들이 상기 PL 측정구간내에서 서로 동일한 비전송 타이밍이 할당됨을 특징으로 하는, 상향링크 전송 전력의 제어방법. And different remote radio heads are assigned the same non-transmission timing within the PL measurement interval.
  16. 제 15 항에 있어서,The method of claim 15,
    상기 서로 다른 원격 무선 헤드들은 모두 동일한 전력으로 셀 특정 기준 신호를 전송함을 특징으로 하는, 상향링크 전송 전력의 제어방법. And the different remote radio heads transmit cell specific reference signals with the same power.
  17. 상향링크 전송 전력을 제어하는 원격 무선 헤드에 있어서, In the remote radio head for controlling the uplink transmission power,
    단말이 상기 원격 무선 헤드에 대한 상향링크 경로 손실(pathloss: PL) 값을 측정하는데 사용되는 PL 측정 구간 내에서, 비전송 타이밍에 뮤팅 모드로 동작하도록 제어하는 RS 전송 제어부; 및An RS transmission control unit controlling the terminal to operate in a muting mode at non-transmission timing within a PL measurement interval used to measure an uplink pathloss (PL) value for the remote radio head; And
    상기 PL 측정구간 내에서, 상기 비전송 타이밍 이외의 타이밍에 셀 특정 기준 신호를 상기 단말로 전송하고, 상기 PL 측정 구간에서 계산된 상향링크 경로 손실값에 기반한 상향링크 전송 전력으로 전송된 상향링크 신호를 상기 단말로부터 수신하는 RF부를 포함함을 특징으로 하는, 원격 무선 헤드. In the PL measurement section, an uplink signal transmitted with uplink transmission power based on an uplink path loss value calculated in the PL measurement section by transmitting a cell specific reference signal to the terminal at a timing other than the non-transmission timing. Remote unit characterized in that it comprises an RF unit for receiving from the terminal.
  18. 제 11 항에 있어서, The method of claim 11,
    상기 RF부는, 상기 비전송 타이밍을 나타내는 기준신호 스케줄링 정보를 상기 원격 무선 헤드와 함께 협력적 송수신점으로 동작하는 매크로 기지국으로부터 수신하는 것을 포함함을 특징으로 하는, 원격 무선 헤드.And the RF unit receives reference signal scheduling information indicating the non-transmission timing from a macro base station operating as a cooperative transmission / reception point together with the remote radio head.
  19. 제 11 항에 있어서,The method of claim 11,
    상기 기준신호 스케줄링 정보는, The reference signal scheduling information,
    상기 셀 특정 기준 신호의 전송전력정보 및 상기 셀 측정 기준 신호가 영 전력이 되는 주기를 포함하거나, 또는 상기 전송전력정보와, 상기 주기 및 상기 주기내에서 셀 특정 기준 신호가 영 전력이 되지 않는 시점을 지시하는 오프셋을 포함함을 특징으로 하는, 원격 무선 헤드.A period in which the transmission power information of the cell specific reference signal and the cell measurement reference signal become zero power, or a time point at which the transmission power information and the cell specific reference signal do not become zero power within the period and the period. And an offset indicative of the remote radio head.
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