WO2016163431A1 - ユーザ端末及び制御方法 - Google Patents
ユーザ端末及び制御方法 Download PDFInfo
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- WO2016163431A1 WO2016163431A1 PCT/JP2016/061327 JP2016061327W WO2016163431A1 WO 2016163431 A1 WO2016163431 A1 WO 2016163431A1 JP 2016061327 W JP2016061327 W JP 2016061327W WO 2016163431 A1 WO2016163431 A1 WO 2016163431A1
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- user terminal
- discovery signal
- parameter
- resource pool
- discovery
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W8/00—Network data management
- H04W8/005—Discovery of network devices, e.g. terminals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W56/00—Synchronisation arrangements
- H04W56/001—Synchronization between nodes
- H04W56/0015—Synchronization between nodes one node acting as a reference for the others
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/02—Selection of wireless resources by user or terminal
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/20—Control channels or signalling for resource management
Definitions
- the present invention relates to a user terminal and a control method used in a mobile communication system that supports D2D (Device to Device) communication, which is direct inter-terminal communication.
- D2D Device to Device
- 3GPP 3rd Generation Partnership Project
- D2D Device to Device
- the D2D proximity service (D2D ProSe) is a service that enables direct terminal-to-terminal communication within a synchronous cluster composed of a plurality of synchronized user terminals.
- the D2D proximity service includes a D2D discovery procedure (ProSe Discovery) for discovering a nearby terminal and D2D communication (ProSe Communication) that is direct inter-terminal communication.
- a user terminal is a user terminal used in a mobile communication system that supports D2D (Device to Device) communication, which is direct inter-terminal communication, and the user terminal itself is out of cell coverage.
- D2D Device to Device
- a transmission unit that transmits a signal to another user terminal synchronized with the user terminal
- a reception unit that receives a signal from the other user terminal, a resource pool for the D2D discovery signal, and a resource pool for the D2D discovery signal
- a storage unit that stores a transmission probability parameter indicating a probability that the D2D discovery signal is transmitted; and a control unit that executes a process of adjusting the transmission probability parameter according to the resource usage in the resource pool for the D2D discovery signal; .
- the embodiment provides a user terminal and a control method capable of realizing an efficient D2D discovery procedure when a plurality of synchronized user terminals are located outside the cell coverage.
- the user terminal according to the embodiment includes: It is used in a mobile communication system that supports D2D (Device to Device) communication, which is direct communication between terminals.
- D2D Device to Device
- the user terminal outside the cell coverage, a transmission unit that transmits a signal to another user terminal synchronized with the user terminal, a reception unit that receives a signal from the other user terminal, and a resource pool for D2D discovery signal And a storage unit for storing a transmission probability parameter (tx-Probability) indicating a probability that the D2D discovery signal is transmitted in the resource pool for the D2D discovery signal, and according to the resource usage in the resource pool for the D2D discovery signal And a control unit that executes processing for adjusting the transmission probability parameter.
- a transmission probability parameter tx-Probability
- control unit executes a process of transmitting information on the adjustment parameter obtained by adjusting the transmission probability parameter to the other user terminal.
- the user terminal is a synchronization source of the other user terminal.
- the said control part performs the process which also transmits the information regarding the said adjustment parameter, when a synchronizing signal is transmitted to the said other user terminal from the own user terminal.
- control unit adjusts the transmission restriction probability parameter according to the process of detecting the resource usage of the other user terminal in the resource pool for the D2D discovery signal and the detected resource usage And processing to execute.
- the control unit further stops the process of transmitting the D2D discovery signal from the own user terminal while executing the process of detecting the resource usage of the other user terminal.
- control unit executes a process of transmitting a D2D discovery signal based on the adjustment parameter.
- control unit executes a process of transmitting information related to the adjustment parameter to the other user terminal, and then executes a process of transmitting a D2D discovery signal based on the adjustment parameter.
- control unit executes a process of adjusting the transmission probability parameter so that the probability decreases as the resource usage (LOAD) in the resource pool for the D2D discovery signal increases.
- LOAD resource usage
- control unit executes a process of adjusting the transmission probability parameter so that the probability increases as the resource usage amount in the resource pool for the D2D discovery signal decreases.
- the user terminal is used in a mobile communication system that supports D2D communication that is direct inter-terminal communication.
- the user terminal outside cell coverage, a transmission unit that transmits a signal to the other user terminal in synchronization with another user terminal that is a synchronization source, and a reception unit that receives a signal from the other user terminal , A D2D discovery signal resource pool, a storage unit that stores a transmission probability parameter indicating a probability that the D2D discovery signal is transmitted in the D2D discovery signal resource pool, and a control that executes processing for adjusting the transmission probability parameter A section.
- the control unit adjusts the transmission probability parameter using the information regarding the adjustment parameter.
- the adjustment parameter is obtained when the other user terminal adjusts a transmission probability parameter stored in the other user terminal according to a resource usage amount in the resource protocol for the D2D discovery signal. It is a parameter.
- the control method in the user terminal according to the embodiment is used in a mobile communication system that supports D2D communication that is direct inter-terminal communication.
- the user terminal detects the resource usage in the resource pool for the D2D discovery signal outside the cell coverage, and the D2D discovery signal is transmitted in the resource pool for the D2D discovery signal according to the detected resource usage.
- the transmission probability parameter indicating the probability of transmission is adjusted.
- the user terminal transmits information on the adjustment parameter obtained by adjusting the transmission probability parameter to another user terminal synchronized with the user terminal.
- the control method in the user terminal according to the embodiment is used in a mobile communication system that supports D2D communication that is direct inter-terminal communication.
- the user terminal acquires information on adjustment parameters transmitted from other user terminals that are synchronization sources outside the cell coverage, and stores the information on the acquired user parameters using the information on the acquired adjustment parameters.
- Adjust the transmission probability parameter is a parameter indicating a probability that the D2D discovery signal is transmitted in the resource pool for the D2D discovery signal.
- the adjustment parameter is a parameter obtained by the other user terminal adjusting the transmission probability parameter stored in the other user terminal according to the resource usage in the resource pool for the D2D discovery signal. It is.
- the user terminal transmits a D2D discovery signal based on the adjusted transmission probability parameter.
- FIG. 1 is a configuration diagram of an LTE system according to the embodiment.
- the LTE system according to the embodiment includes a UE (User Equipment) 100, an E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 10, and an EPC (Evolved Packet Core) 20.
- UE User Equipment
- E-UTRAN Evolved Universal Terrestrial Radio Access Network
- EPC Evolved Packet Core
- the UE 100 corresponds to a user terminal.
- the UE 100 is a mobile communication device, and performs wireless communication with a connection destination cell (serving cell).
- the configuration of the UE 100 will be described later.
- the E-UTRAN 10 corresponds to a radio access network.
- the E-UTRAN 10 includes an eNB 200 (evolved Node-B).
- the eNB 200 corresponds to a base station.
- the eNB 200 is connected to each other via the X2 interface. The configuration of the eNB 200 will be described later.
- the eNB 200 manages one or a plurality of cells and performs radio communication with the UE 100 that has established a connection with the own cell.
- the eNB 200 has a radio resource management (RRM) function, a user data routing function, a measurement control function for mobility control / scheduling, and the like.
- RRM radio resource management
- Cell is used as a term indicating a minimum unit of a radio communication area, and is also used as a term indicating a function of performing radio communication with the UE 100.
- the EPC 20 corresponds to a core network.
- the EUTRAN 10 and the EPC 20 constitute an LTE system network (LTE network).
- the EPC 20 includes an MME (Mobility Management Entity) / S-GW (Serving-Gateway) 300.
- the MME performs various mobility controls for the UE 100.
- the S-GW controls user data transfer.
- the MME / S-GW 300 is connected to the eNB 200 via the S1 interface.
- FIG. 2 is a block diagram of the UE 100.
- the UE 100 includes an antenna 101, a wireless transceiver 110, a user interface 120, a UICC (Universal Integrated Circuit Card) 130, a battery 140, a memory 150, and a processor 160.
- the memory 150 corresponds to a storage unit
- the processor 160 corresponds to a control unit (controller).
- the memory 150 may be integrated with the processor 160, and this set (that is, a chip set) may be used as a processor 160 '(controller) that constitutes a control unit.
- the controller executes various processes described later and various communication protocols.
- the antenna 101 and the wireless transceiver 110 are used for transmitting and receiving wireless signals.
- the radio transceiver 110 converts the baseband signal (transmission signal) output from the processor 160 into a radio signal and transmits it from the antenna 101. Further, the radio transceiver 110 converts a radio signal received by the antenna 101 into a baseband signal (received signal) and outputs the baseband signal to the processor 160.
- the wireless transceiver 110 and the processor 160 constitute a transmission unit and a reception unit.
- the wireless transceiver 110 may include a plurality of transmitters and / or a plurality of receivers. The embodiment mainly assumes a case where the wireless transceiver 110 includes only one transmitter and one receiver.
- the user interface 120 is an interface with a user who owns the UE 100, and includes, for example, a display, a microphone, a speaker, and various buttons.
- the user interface 120 receives an operation from the user and outputs a signal indicating the content of the operation to the processor 160.
- the UICC 130 is a detachable storage medium that stores subscriber information.
- the UICC 130 may be referred to as a SIM (Subscriber Identity Module) or a USIM (Universal SIM).
- SIM Subscriber Identity Module
- USIM Universal SIM
- the UICC 130 stores a “Pre-configured parameter” to be described later.
- the battery 140 stores power to be supplied to each block of the UE 100.
- the UE 100 is a card type terminal, the UE 100 may not include the user interface 120 and the battery 140.
- the memory 150 stores a program executed by the processor 160 and information used for processing by the processor 160.
- the processor 160 includes a baseband processor that modulates / demodulates and encodes / decodes a baseband signal, and a CPU (Central Processing Unit) that executes programs stored in the memory 150 and performs various processes. .
- the processor 160 may further include a codec that performs encoding / decoding of an audio / video signal.
- the processor 160 executes various processes to be described later and various communication protocols.
- FIG. 3 is a block diagram of the eNB 200.
- the eNB 200 includes an antenna 201, a radio transceiver 210, a network interface 220, a memory 230, and a processor 240 (controller).
- the memory 230 may be integrated with the processor 240, and this set (that is, a chip set) may be used as a processor 240 '(controller) that constitutes a control unit.
- the antenna 201 and the wireless transceiver 210 are used for transmitting and receiving wireless signals.
- the radio transceiver 210 converts the baseband signal (transmission signal) output from the processor 240 into a radio signal and transmits it from the antenna 201.
- the radio transceiver 210 converts a radio signal received by the antenna 201 into a baseband signal (received signal) and outputs the baseband signal to the processor 240.
- the wireless transceiver 210 and the processor 240 constitute a transmission unit and a reception unit.
- the network interface 220 is connected to the neighboring eNB 200 via the X2 interface and is connected to the MME / S-GW 300 via the S1 interface.
- the network interface 220 is used for communication performed on the X2 interface and communication performed on the S1 interface.
- the memory 230 stores a program executed by the processor 240 and information used for processing by the processor 240.
- the processor 240 includes a baseband processor that performs modulation / demodulation and encoding / decoding of a baseband signal, and a CPU that executes programs stored in the memory 230 and performs various processes.
- the processor 240 executes various processes and various communication protocols described later.
- FIG. 4 is a protocol stack diagram of a radio interface in the LTE system. As shown in FIG. 4, the radio interface protocol is divided into the first to third layers of the OSI reference model, and the first layer is a physical (PHY) layer.
- the second layer includes a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, and a PDCP (Packet Data Convergence Protocol) layer.
- the third layer includes an RRC (Radio Resource Control) layer.
- the physical layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Between the physical layer of UE100 and the physical layer of eNB200, user data and a control signal are transmitted via a physical channel.
- the MAC layer performs data priority control, retransmission processing by hybrid ARQ (HARQ), and the like. Between the MAC layer of the UE 100 and the MAC layer of the eNB 200, user data and control signals are transmitted via a transport channel.
- the MAC layer of the eNB 200 includes a scheduler that determines (schedules) uplink / downlink transport formats (transport block size, modulation / coding scheme) and resource blocks allocated to the UE 100.
- the RLC layer transmits data to the RLC layer on the receiving side using the functions of the MAC layer and the physical layer. Between the RLC layer of the UE 100 and the RLC layer of the eNB 200, user data and control signals are transmitted via a logical channel.
- the PDCP layer performs header compression / decompression and encryption / decryption.
- the RRC layer is defined only in the control plane that handles control signals. Control signals (RRC messages) for various settings are transmitted between the RRC layer of the UE 100 and the RRC layer of the eNB 200.
- the RRC layer controls the logical channel, the transport channel, and the physical channel according to establishment, re-establishment, and release of the radio bearer.
- RRC connection When there is a connection (RRC connection) between the RRC of the UE 100 and the RRC of the eNB 200, the UE 100 is in the RRC connected mode, otherwise, the UE 100 is in the RRC idle mode.
- the NAS (Non Access Stratum) layer located above the RRC layer performs session management and mobility management.
- the physical layer or the RRC layer constitutes an AS (Access Stratum) entity 100A.
- the NAS layer constitutes the NAS entity 100B.
- the functions of the AS entity 100A and the NAS entity 100B are executed by the processor 160 (control unit). That is, the processor 160 (control unit) includes the AS entity 100A and the NAS entity 100B.
- the AS entity 100A performs cell selection / reselection, and the NAS entity 100B performs PLMN selection.
- FIG. 5 is a configuration diagram of a radio frame used in the LTE system.
- OFDMA Orthogonal Frequency Division Multiple Access
- SC-FDMA Single Carrier Frequency Multiple Access
- the radio frame is composed of 10 subframes arranged in the time direction.
- Each subframe is composed of two slots arranged in the time direction.
- the length of each subframe is 1 ms, and the length of each slot is 0.5 ms.
- Each subframe includes a plurality of resource blocks (RB) in the frequency direction and includes a plurality of symbols in the time direction.
- Each resource block includes a plurality of subcarriers in the frequency direction.
- One subcarrier and one symbol constitute a resource element.
- the frequency resource is configured by a resource block
- the time resource is configured by a subframe (or slot).
- the D2D discovery procedure is mainly described for the D2D proximity service according to the embodiment.
- the LTE system according to the embodiment supports D2D proximity service.
- the D2D proximity service is a service that enables direct UE-to-UE communication within a synchronized cluster composed of a plurality of synchronized UEs 100.
- the D2D proximity service includes a D2D discovery procedure (ProSe Discovery) for discovering a nearby UE and D2D communication (ProSe Communication) that is direct UE-to-UE communication.
- the D2D communication may be referred to as “Direct communication”.
- a scenario in which all the UEs 100 forming the synchronous cluster are located in the cell coverage is referred to as “in coverage”.
- a scenario in which all UEs 100 forming a synchronous cluster are located outside cell coverage is referred to as “out of coverage”.
- a scenario in which some UEs 100 in the synchronization cluster are located within the cell coverage and the remaining UEs 100 are located outside the cell coverage is referred to as “partial coverage”.
- FIG. 6 is a diagram illustrating an operating environment according to the embodiment.
- FIG. 6 shows a state where the UE 100-1, UE 100-2, and UE 100-3 are using the D2D proximity service outside the coverage of the eNB 200.
- three UEs 100 are shown, but at least two UEs may be used.
- UE 100-1 is the synchronization source and UE 100-2 and UE 100-3 are the asynchronous sources.
- the UE 100-1, UE 100-2, and UE 100-3 are synchronized with each other using the UE 100-1 as a synchronization source.
- the UE 100-1, the UE 100-2, and the UE 100-3 execute the D2D discovery procedure while being synchronized with each other.
- each UE 100 (UE 100-1, UE 100-2, UE 100-3) transmits a D2D discovery signal (Discovery signal) for discovering neighboring terminals.
- a D2D discovery signal (Discovery signal) for discovering neighboring terminals.
- Type1 discovery As a method of D2D discovery procedure, a first method (Type1 discovery) in which radio resources that are not uniquely allocated to UE 100 are used for transmission of D2D discovery signals, and radio resources that are uniquely allocated to each UE 100 are D2D discovery signal There is a second method (Type2 discovery) used for transmission.
- a resource pool for D2D discovery signals is used for transmission of D2D discovery signals.
- the resource pool for the D2D discovery signal is shared in a synchronization cluster including a plurality of synchronized UEs 100.
- FIG. 7 is a diagram showing a configuration of a resource pool for the D2D discovery signal.
- the resource pool (Direct Discovery Resource Pools) for the D2D discovery signal is configured in the UP link.
- the resource pool for the D2D discovery signal can be configured in a resource region having a bandwidth of 10 MHz (50 lithos submalock) and a time direction of 40 ms.
- the resource pool for the D2D discovery signal is Xsec (X is, for example, “0.32” / “0.64” / “1.28” / “2.56” / “5.12” / “10.24 It can be any one value of “)”.
- the synchronized UEs 100 transmit the D2D discovery signal using time / frequency resources (resource blocks) in the resource pool for the D2D discovery signal.
- the resource pool for D2D discovery signal may be shared with the resource pool for D2D communication.
- the configuration of the resource pool for the D2D discovery signal and other information elements (such as “tx-Probability parameter” described later) described above are pre-configured.
- the preset parameters are hereinafter referred to as “Pre-configured parameters”.
- each information element (configuration of D2D discovery signal resource pool and other information elements) included in the Pre-configured parameter is the same for UEs used for the same purpose (military, fire, police, etc.).
- the pre-configured parameter is set.
- individual tx-Probability parameters can be set for each resource pool.
- the information indicating the configuration of the resource pool for the D2D discovery signal includes a parameter (offset value for starting position designation) that specifies a time / frequency region in which the resource pool for the D2D discovery signal is first configured in the radio frame.
- a parameter for specifying a frequency direction resource in the resource pool for the D2D discovery signal (frequency direction resource designation parameter), a repetition period (period) of the resource pool for the D2D discovery signal, and a specific subframe of the D2D discovery procedure Information indicating whether it is a time / frequency resource that can be used (bitmap information).
- the Pre-configured parameter is provided to the UE 100.
- the Pre-configured parameter is stored in advance in the UICC 130 of the UE 100. If the Pre-configured parameter is not stored in the UICC 130 in advance, the UE 100 may be stored in the memory 150 by receiving provision from the network (OAM or the like) via the eNB at a predetermined opportunity.
- the tx-Probability parameter indicates the transmission probability of the D2D discovery signal (announcement in a discovery) in the resource pool for the D2D discovery signal.
- the tx-Probability parameter includes “P25” indicating that the transmission probability is 25%, “P50” indicating that the transmission probability is 50%, “P75” indicating that the transmission probability is 75%, and transmission.
- “P100” indicating that the probability is 100% is defined. Incidentally, “P100” means that a D2D discovery signal is always transmitted by a time / frequency resource in a resource pool for a certain D2D discovery signal.
- one tx-Probability parameter (any one of “P25”, “P50”, “P75”, and “P100”) is set as a Pre-configured parameter for one UE 100.
- the tx-Probability parameter may be defined by a value other than “P25”, “P50”, “P75”, and “P100”.
- the plurality of UEs 100 configuring the synchronous cluster that is out of coverage may operate in the first scheme.
- Each UE 100 has one tx-Probability parameter (may be a common parameter or a different parameter).
- Each UE 100 selects a time / frequency resource in the resource pool for the D2D discovery signal based on a predetermined selection criterion according to the tx-Probability parameter that the UE 100 has, and uses the selected time / frequency resource. Transmit D2D discovery signal.
- a situation of transmission delay of D2D discovery signal is assumed. This can occur when a resource pool for a certain D2D discovery signal uses a small amount of time / frequency resources for D2D discovery signal transmission (low load state). For example, the UE 100 having the tx-Probability parameter of “P25” has a low D2D discovery signal transmission probability in its own UE 100 even though the resource pool for the D2D discovery signal is in a low load state. There is a high possibility that the D2D discovery signal is not transmitted in the resource pool for the discovery signal. Then, when the D2D discovery signal is not transmitted in the resource pool for the D2D discovery signal, it is necessary to wait for the next resource pool opportunity for the D2D discovery signal. For this reason, transmission delay of the D2D discovery signal may occur.
- a situation of a collision of D2D discovery signals is assumed. This can occur when a resource pool for a certain D2D discovery signal uses a large amount of time / frequency resources for D2D discovery signal transmission (high load state).
- the UE 100 having the tx-Probability parameter of “P100” has a high transmission probability of the D2D discovery signal in the own UE 100 even though the resource pool for the D2D discovery signal is in a high load state. There is a high possibility of transmitting the D2D discovery signal in the resource pool for the discovery signal.
- FIG. 8 is a sequence diagram illustrating an operation state according to the embodiment.
- controller 160 (160 ') of this UE100 performs a process, in description of FIG. 8, it demonstrates as what UE100 performs for convenience.
- a plurality of UEs 100 perform the D2D discovery procedure outside the coverage.
- the UE 100-1 is a synchronization source
- the other UEs 100 are asynchronous sources.
- a plurality of UEs 100 are synchronized with each other using the UE 100-1 as a synchronization source.
- each UE 100 of a plurality of UEs 100 transmits information indicating the configuration of the resource pool for the D2D discovery signal and a Pre-configured parameter including the tx-Probability parameter to the UICC 130 in advance.
- the UE 100-1 sets “ ⁇ ” as the tx-Probability parameter. “ ⁇ ” is assumed to be any one of “P25”, “P50”, “P75”, and “P100” described above. “ ⁇ ” may be other than “P25”, “P50”, “P75”, and “P100”.
- the UEs 100-2 to 100-N are any one of information indicating the configuration of the resource pool for the D2D discovery signal and tx-Probability parameters (“ ⁇ ”, “ ⁇ ”, “ ⁇ ”... ) Including pre-configured parameters are stored in the UICC 130 in advance.
- ⁇ ”, “ ⁇ ”, “ ⁇ ”... Indicate the transmission probabilities shown above, and “ ⁇ ”, “ ⁇ ”, “ ⁇ ”... Indicate different transmission probabilities. .
- the UE 100-1 as the synchronization source is interested in transmitting the D2D discovery signal (step S1).
- the synchronization source UE 100-1 monitors the D2D discovery signal from the other UEs 100-2 to N in the resource pool for the D2D discovery signal, and detects the D2D discovery signal from the other UEs 1002 to N. As a result, the UE 100-1 checks (calculates / detects) the usage amount (Discovery Load) of the time / frequency resource in which the D2D discovery signal is transmitted in the resource pool for the D2D discovery signal (step S2).
- the UE 100-1 has the opportunity to transmit the D2D discovery signal from the own UE 100-1 based on the information indicating the configuration of the resource pool for the D2D discovery signal stored in the UICC 130 of the own UE 100-1 (D2D discovery). Even when the signal resource pool period) arrives, the process of transmitting the D2D discovery signal from the user terminal is stopped.
- the UE 100-1 adjusts (changes / selects / generates / calculates) the tx-Probability parameter according to the usage amount of the time / frequency resource. ) Is executed (step S3).
- step S3 the UE 100-1 adjusts the tx-Probability parameter from “ ⁇ ” to “ ⁇ ” according to the usage amount of the time / frequency resource in which the D2D discovery signal is transmitted.
- the UE 100-1 stores the adjusted tx-Probability parameter “ ⁇ ” in the UICC 130 by overwriting it or stores it in the memory 150. The specific contents of the stored adjustment process will be described again.
- the UE 100-1 includes information regarding the adjusted tx-Probability parameter “ ⁇ ” (adjustment parameter) in, for example, an MIB-SL (Master Information Block-Sidelink) message (control information), and A radio signal including SL is broadcast for UEs 100-2 to 100-N (step S4).
- the UE 100-1 may notify the information regarding the adjusted tx-Probability parameter “ ⁇ ” in a control message other than the MIB-SL.
- step S4 the information regarding the adjusted tx-Probability parameter “ ⁇ ” notified by the UE 100-1 is information indicating “ ⁇ ” itself.
- the information related to the adjusted tx-Probability parameter “ ⁇ ” is identification information (such as an offset value from the previously stored transmission probability) that allows UEs 100-2 to N to indirectly recognize “ ⁇ ”. May be.
- the UEs 100-2 to 100-N Upon receiving the radio signal including the MIB-SL broadcasted from the UE 100-1, the UEs 100-2 to 100-N temporarily store information about the adjusted tx-Probability parameter “ ⁇ ” included in the MIB-SL in the memory 150.
- the UEs 100-2 to 100 -N adjust (change / select) the tx-Probability parameter stored in the UICC 130 of the own UE 100 to become the adjusted tx-Probability parameter “ ⁇ ” stored in the memory 150.
- Generate / calculate is executed (step S5).
- the UEs 100-2 to N receive the D2D discovery signal based on the information indicating the configuration of the resource pool for the D2D discovery signal stored in the UICC 130 of the UE 100 and the adjusted tx-Probability parameter “ ⁇ ”. To transmit.
- the UE 100-1 broadcasts the radio signal including the MIB-SL, and then stores the information indicating the configuration of the resource pool for the D2D discovery signal stored in the UICC 130 of the own UE 100-1 and the adjusted post-adjustment stored. Based on the tx-Probability parameter “ ⁇ ”, the D2D discovery signal is transmitted for the UEs 100-2 to 100-N (step S6).
- the UE 100-1 and the UEs 100-2 to 100-N then repeat the processing of the steps S1 to S6.
- the UE 100-1 and the UEs 100-2 to N may adjust the tx-Probability parameter so that it returns to the initial value after the processing of the steps S1 to S6 is repeated a predetermined number of times or after a predetermined time has elapsed. .
- Example of tx-Probability parameter adjustment An example of adjusting the tx-Probability parameter in step S3 will be described.
- the UE 100-1 shows that the more the usage amount of the time / frequency resource, the lower the tx-Probability parameter Adjust to. For example, if the tx-Probability parameter “ ⁇ ” is “P100”, the tx-Probability parameter is lower than “P100” (at least one of “P75”, “P50”, or “P25”) Adjust so that
- the UE 100-1 adjusts so that the tx-Probability parameter becomes a higher value as the usage amount of the time / frequency resource is smaller. To do. For example, if the tx-Probability parameter “ ⁇ ” is “P25”, the tx-Probability parameter is larger than “P25” (at least one of “P50”, “P75”, and “P100”). Adjust so that
- the tx-Probability parameter can be adjusted according to the usage amount (Discovery Load) of the time / frequency resource in which the D2D discovery signal is transmitted. For this reason, in the scenario “out of coverage”, transmission delay and collision of the D2D discovery signal can be efficiently suppressed between the plurality of user terminals.
- the UE 100-1 informs the UEs 100-2 to N of information regarding one adjusted tx-Probability parameter.
- the UE 100-1 is configured to transmit the D2D discovery signal transmission time.
- a plurality of tx-Probability parameters may be generated according to the usage amount of the frequency resource, and information on the generated plurality of tx-Probability parameters may be notified to the UEs 100-2 to 100-N.
- more appropriate information can be selected and used from information regarding a plurality of tx-Probability parameters based on its own operating environment.
- the UE 100-1 can also be implemented in a scenario in which D2D communication by Mode-2 is performed “out of coverage”.
- the operation of “Mode-2” in the D2D communication means an operation in which the UE 100 selects a radio resource for transmitting D2D data (D2D data and / or control data) from the resource pool.
- UE 100-1 adjusts the tx-Probability parameter (one or more parameters) for the resource pool for D2D communication in “Mode-2” in D2D communication
- UE 100-1 sets the adjusted tx-Probability parameter to UE 100-2 ⁇ N can be sent.
- a D2D discovery signal is transmitted in a resource pool for D2D communication.
- This scenario may be referred to as “Discovery through Communication (DtC)”.
- DtC Discovery through Communication
- the UE 100-1 adjusts the tx-Probability parameter (one or more parameters) for the resource pool for D2D communication capable of transmitting the D2D discovery signal in this “DtC” scenario, the adjusted tx-Probability parameter May be transmitted to the UEs 100-2 to N.
- two operation modes (Mode-1 / Mode-2) of D2D communication are defined. Of the two modes, Mode-2 is as described above.
- the eNB 200 or a relay node (not shown) allocates radio resources for transmitting D2D data (D2D data and / or control data).
- the LTE system has been described as an example of the mobile communication system.
- the present invention is not limited to the LTE system, and the present invention may be applied to a system other than the LTE system.
- ProSe UE should select an appropriate SLSS transmission method based on public safety discovery or commercial discovery operation.
- the serving cell / PCell may configure the ProSe UE with multiple transmission resource pools and pool selection (based on random / RSRP) methods.
- the ProSe UE may configure the ProSe UE with multiple transmission resource pools and pool selection (based on random / RSRP) methods.
- there is no pool selection scheme for communication in the preset parameters there is no pool selection scheme for communication in the preset parameters.
- it may not be necessary to reuse the pool selection scheme for within network coverage.
- a new pool selection scheme based on discovery range may be useful.
- Proposal 2 It should be considered whether a pool selection scheme based on the discovery range is necessary.
- the serving cell / PCell may set txProbability to control the discovery message load generated by the type 1 discovery announcement.
- the serving cell / PCell may set txProbability via dedicated signaling / broadcast signaling.
- txProbability can be adjusted based on the type 1 discovery resource pool selection (depending on the eNB implementation).
- txProbability cannot be adjusted based on resource pool selection.
- a load control mechanism for out of network coverage is required, how to select an appropriate value for txProbability, for example based on the number of discovery messages in the resource pool or based on the received power of the discovery resource pool , Etc. need to be considered.
- Proposal 3 It is necessary to consider whether a load control mechanism for outside network coverage is necessary.
- the present invention is useful in the communication field.
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Abstract
Description
D2D ProSeでは、同期がとられた複数のユーザ端末がセルカバレッジ外に位置するシナリオ(Out of coverage)が想定されている。かかるシナリオでは、セルカバレッジ外に位置する複数のユーザ端末が、ネットワークを介さずに直接的に端末間通信を実行する。このため、このシナリオにおける最適な運用のために、複数のユーザ端末間で効率良くD2D発見手続が行われることが望まれている。
以下において、本発明をLTEシステムに適用する場合の実施形態を説明する。
図1は、実施形態に係るLTEシステムの構成図である。図1に示すように、実施形態に係るLTEシステムは、UE(User Equipment)100、E-UTRAN(Evolved Universal Terrestrial Radio Access Network)10、及びEPC(Evolved Packet Core)20を備える。
以下において、実施形態に係るD2D近傍サービスについて、D2D発見手続を主として説明する。実施形態に係るLTEシステムは、D2D近傍サービスをサポートする。
tx-Probabilityパラメータは、D2D発見信号用のリソースプールにおけるD2D発見信号(announcement in a discovery)の送信確率を示す。tx-Probabilityパラメータは、送信確率が25%であることを示す「P25」、送信確率が50%であることを示す「P50」、送信確率が75%であることを示す「P75」、及び送信確率が100%であることを示す「P100」が規定される。ちなみに、「P100」は、D2D発見信号が、或るD2D発見信号用のリソースプール内の時間・周波数リソースによって必ず伝送されることを意味する。
上述したように、カバレッジ外にいる同期クラスタを構成する複数のUE100は、第1の方式で動作し得る。各UE100は、それぞれ1つのtx-Probabilityパラメータ(共通のパラメータでもよいし異なるパラメータでもよい)を持っている。各UE100は、自分が持っているtx-Probabilityパラメータに従って、それぞれがD2D発見信号用のリソースプール内の時間・周波数リソースを所定の選択基準に基づいて選択し、選択した時間・周波数リソースを使ってD2D発見信号を伝送する。
以下、図8に基づいて、本実施形態の動作内容について説明する。図8は、実施形態に係る動作状態を示すシーケンス図である。尚、UE100が実行する処理については、該UE100のコントローラ160(160’)が処理を実行するが、図8の説明においては、便宜上、UE100が行うものとして説明する。
ステップS3におけるtx-Probabilityパラメータの調整例について説明する。UE100-1は、ステップS2において、D2D発見信号が伝送される時間・周波数リソースの使用量をチェックした結果、該時間・周波数リソースの使用量が多いほど、tx-Probabilityパラメータが低い値となるように調整する。例えば、tx-Probabilityパラメータ「α」が「P100」であれば、tx-Probabilityパラメータを「P100」よりも下回る値(「P75」か「P50」か「P25」のうち、少なくともいずれか一つ)になるように調整する。
本実施形態では、上述したように、D2D発見信号が伝送される時間・周波数リソースの使用量(Discovery Load)に応じて、tx-Probabilityパラメータを調整できる。このため、「カバレッジ外」でのシナリオにおいて、複数のユーザ端末間で、D2D発見信号の送信遅延や衝突を効率良く抑制できる。
以下の目的が含まれるWIDが合意される。
同期処理について考慮すべきものは、Rel-12に仕様化されるセル間発見シナリオである。現在の仕様によれば、カバレッジの縁部に近いInCのUEは、発見送信用リソースプールの先頭(に最も近いサブフレーム)を介して一回限りのSLSSのみを送信することによって、発見動作を行える。よって、カバレッジの縁部に近いInCのUEは、公衆安全発見又は商用発見動作に基づいて適切なSLSS送信方法を選択すべきである。
(プール選択)
ネットワークカバレッジ内の動作では、サービングセル/PCellは、複数の送信リソースプール及びプール選択(ランダム/RSRPに基づく)の方法をProSe UEに設定し得る。一方、ネットワークカバレッジ外の動作では、事前設定されたパラメータに、通信のためのプール選択スキームが存在しない。よって、ネットワークカバレッジ内のためのプール選択スキームを再利用する必要がないかもしれない。しかし、発見範囲の側面を考慮すると、発見範囲に基づく新しいプール選択スキームは有用であり得る。
サービングセル/PCellは、type1発見アナウンスによって生成される発見メッセージの負荷を制御するために、txProbabilityを設定し得る。サービングセル/PCellは、専用シグナリング/ブロードキャストシグナリングを介してtxProbabilityを設定し得る。よって、txProbabilityは、type1発見リソースプール選択に基づいて調整され得る(eNB実装によって)。しかし、ネットワークカバレッジ外の状況では、txProbabilityが再利用される場合において、これをProSe UEに事前設定する必要があり、よって、リソースプール選択に基づいてtxProbabilityを調整することができない。ネットワークカバレッジ外のための負荷制御メカニズムが必要であれば、txProbabilityの適切な値をどのように選択するか、例えば、リソースプールにおける発見メッセージの数に基づくか、発見リソースプールの受信電力に基づくか、等を検討する必要がある。
本付記において、部分的ネットワークカバレッジ及びネットワークカバレッジ外のための考察及び提案がある。
米国仮出願第62/145739号(2015年4月10日)の全内容が参照により本願明細書に組み込まれている。
Claims (11)
- 直接的な端末間通信であるD2D(Device to Device)通信をサボートする移動通信システムにおいて用いられるユーザ端末であって、
セルカバレッジ外において、自ユーザ端末に同期する他のユーザ端末に信号を送信する送信部と、
前記他のユーザ端末からの信号を受信する受信部と、
D2D発見信号用のリソースプールおよび当該D2D発見信号用のリソースプールにおいてD2D発見信号が送信される確率を示す送信確率パラメータを記憶する記憶部と、
前記D2D発見信号用のリソースプールにおけるリソース使用量に応じて、前記送信確率パラメータを調整する処理を実行する制御部と、を備えることを特徴とするユーザ端末。 - 前記制御部は、前記送信確率パラメータを調整することによって得られた調整パラメータに関する情報を、前記他のユーザ端末に送信する処理を実行する前記請求項1記載のユーザ端末。
- 前記ユーザ端末は、前記他のユーザ端末の同期元であり、
前記制御部は、自ユーザ端末から前記他のユーザ端末に同期信号を送信するときに、前記調整パラメータに関する情報も送信する処理を実行する前記請求項2記載のユーザ端末。 - 前記制御部は、前記D2D発見信号用のリソースプールにおける前記他のユーザ端末のリソース使用量を検出する処理と、検出した前記リソース使用量に応じて、前記送信制限確率パラメータを調整する処理と、を実行し、
前記制御部は、更に、前記他のユーザ端末のリソース使用量を検出する処理を実行する間、自ユーザ端末からD2D発見信号を送信する処理を停止する前記請求項1記載のユーザ端末。 - 前記制御部は、前記調整パラメータに基づいて、D2D発見信号を送信する処理を実行する前記請求項1記載のユーザ端末。
- 前記制御部は、前記調整パラメータに関する情報を前記他のユーザ端末に送信する処理を実行した後、当該調整パラメータに基づいて、D2D発見信号を送信する処理を実行する前記請求項1記載のユーザ端末。
- 前記制御部は、前記D2D発見信号用のリソースプールにおけるリソース使用量が多いほど、前記確率が低くなるように前記送信確率パラメータを調整する処理を実行する前記請求項1記載のユーザ端末。
- 前記制御部は、前記D2D発見信号用のリソースプールにおけるリソース使用量が少ないほど、前記確率が高くなるように前記送信確率パラメータを調整する処理を実行する前記請求項1記載のユーザ端末。
- 直接的な端末間通信であるD2D(Device to Device)通信をサボートする移動通信システムにおいて用いられるユーザ端末であって、
セルカバレッジ外において、同期元である他のユーザ端末に同期して当該他のユーザ端末に信号を送信する送信部と、
前記他のユーザ端末からの信号を受信する受信部と、
D2D発見信号用のリソースプールおよび当該D2D発見信号用のリソースプールにおいてD2D発見信号が送信される確率を示す送信確率パラメータを記憶する記憶部と、
前記送信確率パラメータを調整する処理を実行する制御部と、を備え、
前記制御部は、前記他の端末から送信された調整パラメータに関する情報を取得した場合には、前記調整パラメータに関する情報を使用して前記送信確率パラメータを調整し、
前記調整パラメータは、前記他のユーザ端末が、前記D2D発見信号用のリソースプールにおけるリソース使用量に応じて、前記他のユーザ端末において記憶されていた送信確率パラメータを調整することによって得られたパラメータであるユーザ端末。 - 直接的な端末間通信であるD2D(Device to Device)通信をサボートする移動通信システムにおいて用いられるユーザ端末における制御方法であって、
前記ユーザ端末は、セルカバレッジ外において、D2D発見信号用のリソースプールにおけるリソース使用量を検出し、
前記検出されたリソース使用量に応じて、前記D2D発見信号用のリソースプールにおいてD2D発見信号が送信される確率を示す送信確率パラメータを調整し、
前記送信確率パラメータを調整することによって得られた調整パラメータに関する情報を、自ユーザ端末に同期する他のユーザ端末に送信する制御方法。 - 直接的な端末間通信であるD2D(Device to Device)通信をサポートする移動通信システムにおいて用いられるユーザ端末における制御方法であって、
前記ユーザ端末は、セルカバレッジ外において、同期元である他のユーザ端末から送信された調整パラメータに関する情報を取得し、
前記取得された調整パラメータに関する情報を使用して、自ユーザ端末において記憶していた送信確率パラメータを調整し、
前記送信確率パラメータは、D2D発見信号用のリソースプールにおいてD2D発見信号が送信される確率を示すパラメータであり、
前記調整パラメータは、前記他のユーザ端末が、前記D2D発見信号用のリソースプールにおけるリソース使用量に応じて、当該他のユーザ端末において記憶されていた送信確率パラメータを調整することによって得られたパラメータであり、
前記ユーザ端末は、前記調整された送信確率パラメータに基づいて、D2D発見信号を送信する制御方法。
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