WO2013151360A1 - 무선 통신 시스템에서 mbms 기반 셀 재선택 방법 및 이를 지원하는 장치 - Google Patents
무선 통신 시스템에서 mbms 기반 셀 재선택 방법 및 이를 지원하는 장치 Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/06—Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0007—Control or signalling for completing the hand-off for multicast or broadcast services, e.g. MBMS
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0055—Transmission or use of information for re-establishing the radio link
- H04W36/0069—Transmission or use of information for re-establishing the radio link in case of dual connectivity, e.g. decoupled uplink/downlink
- H04W36/00695—Transmission or use of information for re-establishing the radio link in case of dual connectivity, e.g. decoupled uplink/downlink using split of the control plane or user plane
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/08—Reselecting an access point
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/20—Selecting an access point
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/08—Access restriction or access information delivery, e.g. discovery data delivery
- H04W48/12—Access restriction or access information delivery, e.g. discovery data delivery using downlink control channel
Definitions
- the present invention relates to wireless communication, and more particularly, to a cell reselection method based on MBMS (Multicast Broadcast Multimedia Service) in a wireless communication system and an apparatus supporting the same.
- MBMS Multicast Broadcast Multimedia Service
- 3GPP LTE long term evolution
- UMTS Universal Mobile Telecommunications System
- 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in downlink and single carrier-frequency division multiple access (SC-FDMA) in uplink.
- OFDMA orthogonal frequency division multiple access
- SC-FDMA single carrier-frequency division multiple access
- MIMO multiple input multiple output
- LTE-A 3GPP LTE-Advanced
- the terminal represented by the mobile device moves, the quality of the currently provided service may be degraded, or a cell capable of providing a better service may be found. As a result, the terminal may move to a new cell.
- the terminal In order for the terminal to move to a new cell, the terminal continuously performs measurements on the serving cell and the adjacent cell. When the measurement result satisfies the condition for performing mobility, the terminal may receive an indication from the serving cell or move directly.
- the terminal may be provided with an enhanced service by maintaining a connection to a cell providing a specific service or a cell to which access is allowed. For example, it may be desirable for a terminal that wants to receive a Multicast Broadcast Multimedia Service (MBMS) to be provided with a service by accessing a cell providing the MBMS. As a method for this, a separate priority may be applied to the frequency of the cell providing the MBMS so that the UE may reselect the cell where the MBMS is provided.
- MBMS Multicast Broadcast Multimedia Service
- a UE that is receiving or wants to receive an MBMS may perform cell reselection by applying a higher priority to a frequency at which the MBMS is expected to be provided if it is out of coverage of the cell providing the MBMS.
- the target cell selected through the cell reselection as described above may be a cell that does not actually provide the MBMS, and accessing such a cell by the UE may be contrary to the original purpose of performing cell reselection by adjusting the priority. .
- An object of the present invention is to provide an MBMS-based cell reselection method performed by a terminal in a wireless communication system.
- a cell reselection method performed by a terminal in a wireless communication system determines whether system information for a multicast broadcast multimedia service (MBMS) is broadcast from a neighbor cell, and if system information for the MBMS is broadcast, applies a highest priority to a frequency of the neighbor cell. Performing a reselection.
- MBMS multicast broadcast multimedia service
- the system information for the MBMS may be a System Information Block (SIB) 13 of system information broadcast from the neighbor cell.
- SIB System Information Block
- the method may further include performing cell reselection by applying a signaled priority to a frequency of the neighboring cell if system information for the MBMS is not broadcast.
- the terminal may be receiving an MBMS or may be interested in receiving an MBMS service.
- a preparation timer associated with a time interval not applying the highest priority for the frequency a timer may be further included.
- the method may further comprise resetting the formulation timer if an MBMS service is provided at the frequency.
- the method may further include resetting the preparation timer when the serving cell of the terminal is changed.
- the method may further comprise resetting the formulation timer if the tracking area is changed.
- a wireless device operating in a wireless communication system includes a Radio Frequency (RF) unit for transmitting and receiving radio signals and a processor operatively coupled to the RF unit.
- the processor determines whether system information for a multicast broadcast multimedia service (MBMS) is broadcast from a neighbor cell, and if system information for the MBMS is broadcast, applies a highest priority to a frequency of the neighbor cell to reconfigure a cell. Is set to perform the selection.
- MBMS multicast broadcast multimedia service
- the UE can be prevented from actually accessing the cell of the frequency where the MBMS is not provided.
- the terminal may determine whether the MBMS is actually provided in the cell and may not apply the highest priority to the frequency of the cell.
- the UEs can select and approach another cell on a high priority frequency instead of a cell having a low frequency priority without providing an MBMS.
- the terminal may avoid access to a crowded cell, thereby receiving a more efficient service, and the network may provide an efficient service through appropriate load balancing.
- FIG. 1 shows a wireless communication system to which the present invention is applied.
- FIG. 2 is a block diagram illustrating a radio protocol architecture for a user plane.
- FIG. 3 is a block diagram illustrating a radio protocol structure for a control plane.
- FIG. 4 is a flowchart illustrating an operation of a terminal in an RRC idle state.
- FIG. 5 is a flowchart illustrating a process of establishing an RRC connection.
- FIG. 6 is a flowchart illustrating a RRC connection resetting process.
- FIG. 7 is a diagram illustrating a RRC connection reestablishment procedure.
- FIG. 8 is a diagram illustrating an example of cell reselection performed by a terminal related to an MBMS.
- FIG. 9 is a flowchart illustrating cell reselection according to an embodiment of the present invention.
- FIG. 10 is a flowchart illustrating an example of a cell reselection method according to an embodiment of the present invention.
- FIG. 11 is a diagram illustrating an example of terminal movement when a cell reselection method according to an embodiment of the present invention is applied.
- FIG. 12 is a block diagram illustrating a wireless device in which an embodiment of the present invention is implemented.
- E-UTRAN Evolved-UMTS Terrestrial Radio Access Network
- LTE Long Term Evolution
- the E-UTRAN includes a base station (BS) 20 that provides a control plane and a user plane to a user equipment (UE).
- the terminal 10 may be fixed or mobile and may be called by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), a wireless device (Wireless Device), and the like.
- the base station 20 refers to a fixed station communicating with the terminal 10, and may be referred to by other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, and the like.
- eNB evolved-NodeB
- BTS base transceiver system
- access point and the like.
- the base stations 20 may be connected to each other through an X2 interface.
- the base station 20 is connected to a Serving Gateway (S-GW) through an MME (Mobility Management Entity) and an S1-U through an Evolved Packet Core (EPC) 30, more specifically, an S1-MME through an S1 interface.
- S-GW Serving Gateway
- MME Mobility Management Entity
- EPC Evolved Packet Core
- EPC 30 is composed of MME, S-GW and P-GW (Packet Data Network-Gateway).
- the MME has information about the access information of the terminal or the capability of the terminal, and this information is mainly used for mobility management of the terminal.
- S-GW is a gateway having an E-UTRAN as an endpoint
- P-GW is a gateway having a PDN as an endpoint.
- Layers of the Radio Interface Protocol between the terminal and the network are based on the lower three layers of the Open System Interconnection (OSI) reference model, which is widely known in communication systems.
- L2 second layer
- L3 third layer
- the RRC Radio Resource Control
- the RRC layer located in the third layer plays a role of controlling radio resources between the terminal and the network. To this end, the RRC layer exchanges an RRC message between the terminal and the base station.
- FIG. 2 is a block diagram illustrating a radio protocol architecture for a user plane.
- 3 is a block diagram illustrating a radio protocol structure for a control plane.
- the user plane is a protocol stack for user data transmission
- the control plane is a protocol stack for control signal transmission.
- a physical layer (PHY) layer provides an information transfer service to a higher layer using a physical channel.
- the physical layer is connected to a medium access control (MAC) layer, which is an upper layer, through a transport channel. Data is moved between the MAC layer and the physical layer through the transport channel. Transport channels are classified according to how and with what characteristics data is transmitted over the air interface.
- MAC medium access control
- the physical channel may be modulated by an orthogonal frequency division multiplexing (OFDM) scheme and utilizes time and frequency as radio resources.
- OFDM orthogonal frequency division multiplexing
- the functions of the MAC layer include mapping between logical channels and transport channels and multiplexing / demultiplexing into transport blocks provided as physical channels on transport channels of MAC service data units (SDUs) belonging to the logical channels.
- the MAC layer provides a service to a Radio Link Control (RLC) layer through a logical channel.
- RLC Radio Link Control
- RLC layer Functions of the RLC layer include concatenation, segmentation, and reassembly of RLC SDUs.
- QoS Quality of Service
- the RLC layer has a transparent mode (TM), an unacknowledged mode (UM), and an acknowledged mode (Acknowledged Mode).
- TM transparent mode
- UM unacknowledged mode
- Acknowledged Mode acknowledged mode
- AM Three modes of operation (AM).
- AM RLC provides error correction through an automatic repeat request (ARQ).
- the RRC (Radio Resource Control) layer is defined only in the control plane.
- the RRC layer is responsible for the control of logical channels, transport channels, and physical channels in connection with configuration, re-configuration, and release of radio bearers.
- RB means a logical path provided by the first layer (PHY layer) and the second layer (MAC layer, RLC layer, PDCP layer) for data transmission between the terminal and the network.
- PDCP Packet Data Convergence Protocol
- Functions of the Packet Data Convergence Protocol (PDCP) layer in the user plane include delivery of user data, header compression, and ciphering.
- the functionality of the Packet Data Convergence Protocol (PDCP) layer in the control plane includes the transfer of control plane data and encryption / integrity protection.
- the establishment of the RB means a process of defining characteristics of a radio protocol layer and a channel to provide a specific service, and setting each specific parameter and operation method.
- RB can be further divided into SRB (Signaling RB) and DRB (Data RB).
- SRB is used as a path for transmitting RRC messages in the control plane
- DRB is used as a path for transmitting user data in the user plane.
- the UE If an RRC connection is established between the RRC layer of the UE and the RRC layer of the E-UTRAN, the UE is in an RRC connected state, otherwise it is in an RRC idle state.
- the downlink transmission channel for transmitting data from the network to the UE includes a BCH (Broadcast Channel) for transmitting system information and a downlink shared channel (SCH) for transmitting user traffic or control messages.
- Traffic or control messages of a downlink multicast or broadcast service may be transmitted through a downlink SCH or may be transmitted through a separate downlink multicast channel (MCH).
- the uplink transport channel for transmitting data from the terminal to the network includes a random access channel (RACH) for transmitting an initial control message and an uplink shared channel (SCH) for transmitting user traffic or control messages.
- RACH random access channel
- SCH uplink shared channel
- BCCH broadcast control channel
- PCCH paging control channel
- CCCH common control channel
- MCCH multicast control channel
- MTCH multicast traffic
- the physical channel is composed of several OFDM symbols in the time domain and several sub-carriers in the frequency domain.
- One sub-frame consists of a plurality of OFDM symbols in the time domain.
- the RB is a resource allocation unit and includes a plurality of OFDM symbols and a plurality of subcarriers.
- each subframe may use specific subcarriers of specific OFDM symbols (eg, the first OFDM symbol) of the corresponding subframe for the physical downlink control channel (PDCCH), that is, the L1 / L2 control channel.
- Transmission Time Interval is a unit time of subframe transmission.
- the RRC state refers to whether or not the RRC layer of the UE is in a logical connection with the RRC layer of the E-UTRAN. If connected, the RRC connection state is called. Since the UE in the RRC connected state has an RRC connection, the E-UTRAN can grasp the existence of the corresponding UE in a cell unit, and thus can effectively control the UE. On the other hand, the UE of the RRC idle state cannot be recognized by the E-UTRAN, and is managed by the CN (core network) in units of a tracking area, which is a larger area unit than a cell. That is, the UE in the RRC idle state is identified only in a large area unit, and must move to the RRC connected state to receive a normal mobile communication service such as voice or data.
- CN core network
- the terminal When the user first powers on the terminal, the terminal first searches for an appropriate cell and then stays in an RRC idle state in the cell.
- the UE in the RRC idle state needs to establish an RRC connection, it establishes an RRC connection with the E-UTRAN through an RRC connection procedure and transitions to the RRC connected state.
- RRC connection procedure There are several cases in which the UE in RRC idle state needs to establish an RRC connection. For example, an uplink data transmission is necessary due to a user's call attempt, or a paging message is sent from E-UTRAN. If received, a response message may be sent.
- the non-access stratum (NAS) layer located above the RRC layer performs functions such as session management and mobility management.
- EMM-REGISTERED EPS Mobility Management-REGISTERED
- EMM-DEREGISTERED EMM-DEREGISTERED
- the initial terminal is in the EMM-DEREGISTERED state, and the terminal performs a process of registering with the corresponding network through an initial attach procedure to access the network. If the attach procedure is successfully performed, the UE and the MME are in the EMM-REGISTERED state.
- an EPS Connection Management (ECM) -IDLE state In order to manage a signaling connection between the UE and the EPC, two states are defined, an EPS Connection Management (ECM) -IDLE state and an ECM-CONNECTED state, and these two states are applied to the UE and the MME.
- ECM EPS Connection Management
- ECM-IDLE state When the UE in the ECM-IDLE state establishes an RRC connection with the E-UTRAN, the UE is in the ECM-CONNECTED state.
- the MME in the ECM-IDLE state becomes the ECM-CONNECTED state when it establishes an S1 connection with the E-UTRAN.
- the E-UTRAN does not have context information of the terminal.
- the UE in the ECM-IDLE state performs a terminal-based mobility related procedure such as cell selection or cell reselection without receiving a command from the network.
- a terminal-based mobility related procedure such as cell selection or cell reselection without receiving a command from the network.
- the terminal when the terminal is in the ECM-CONNECTED state, the mobility of the terminal is managed by the command of the network.
- the terminal In the ECM-IDLE state, if the position of the terminal is different from the position known by the network, the terminal informs the network of the corresponding position of the terminal through a tracking area update procedure.
- the system information includes essential information that the terminal needs to know in order to access the base station. Therefore, the terminal must receive all system information before accessing the base station, and must always have the latest system information. In addition, since the system information is information that all terminals in a cell should know, the base station periodically transmits the system information.
- the system information includes a master information block (MIB) and a scheduling block (SB). , SIB System Information Block).
- MIB master information block
- SB scheduling block
- the MIB enables the UE to know the physical configuration of the cell, for example, bandwidth.
- SB informs transmission information of SIBs, for example, a transmission period.
- SIB is a collection of related system information. For example, some SIBs contain only information of neighboring cells, and some SIBs contain only information of an uplink radio channel used by the terminal.
- services provided by a network to a terminal can be classified into three types as follows.
- the terminal also recognizes the cell type differently according to which service can be provided. The following describes the service type first, followed by the cell type.
- Limited service This service provides Emergency Call and Tsunami Warning System (ETWS) and can be provided in an acceptable cell.
- ETWS Emergency Call and Tsunami Warning System
- Normal service This service means a public use for general use, and can be provided in a suitable or normal cell.
- This service means service for network operator. This cell can be used only by network operator and not by general users.
- the cell types may be classified as follows.
- Acceptable cell A cell in which the terminal can receive limited service. This cell is a cell that is not barred from the viewpoint of the terminal and satisfies the cell selection criteria of the terminal.
- Suitable cell The cell that the terminal can receive a regular service. This cell satisfies the conditions of an acceptable cell and at the same time satisfies additional conditions. As an additional condition, this cell must belong to a Public Land Mobile Network (PLMN) to which the terminal can access, and must be a cell which is not prohibited from performing a tracking area update procedure of the terminal. If the cell is a CSG cell, the terminal should be a cell that can be connected to the cell as a CSG member.
- PLMN Public Land Mobile Network
- Barred cell A cell that broadcasts information that a cell is a prohibited cell through system information.
- Reserved cell A cell that broadcasts information that a cell is a reserved cell through system information.
- 4 is a flowchart illustrating an operation of a terminal in an RRC idle state. 4 illustrates a procedure in which a UE, which is initially powered on, registers with a network through a cell selection process and then reselects a cell if necessary.
- the terminal selects a radio access technology (RAT) for communicating with a public land mobile network (PLMN), which is a network to be serviced (S410).
- RAT radio access technology
- PLMN public land mobile network
- S410 a network to be serviced
- Information about the PLMN and the RAT may be selected by a user of the terminal or may be stored in a universal subscriber identity module (USIM).
- USIM universal subscriber identity module
- the terminal selects a cell having the largest value among the measured base station and a cell whose signal strength or quality is greater than a specific value (Cell Selection) (S420). This is referred to as initial cell selection by the UE that is powered on to perform cell selection. The cell selection procedure will be described later.
- the terminal receives system information periodically transmitted by the base station.
- the above specific value refers to a value defined in the system in order to ensure the quality of the physical signal in data transmission / reception. Therefore, the value may vary depending on the RAT applied.
- the terminal performs a network registration procedure (S430).
- the terminal registers its information (eg IMSI) in order to receive a service (eg paging) from the network.
- IMSI information
- a service eg paging
- the terminal selects a cell, the terminal does not register to the access network, and if the network information received from the system information (e.g., tracking area identity; TAI) is different from the network information known to the network, the terminal registers to the network. do.
- the system information e.g., tracking area identity; TAI
- the terminal performs cell reselection based on the service environment provided by the cell or the environment of the terminal (S440).
- the terminal selects one of the other cells that provides better signal characteristics than the cell of the base station to which the terminal is connected if the strength or quality of the signal measured from the base station being service is lower than the value measured from the base station of the adjacent cell. do.
- This process is called Cell Re-Selection, which is distinguished from Initial Cell Selection of Step 2.
- a time constraint is placed. The cell reselection procedure will be described later.
- FIG. 5 is a flowchart illustrating a process of establishing an RRC connection.
- the terminal sends an RRC connection request message to the network requesting an RRC connection (S510).
- the network sends an RRC connection setup message in response to the RRC connection request (S520). After receiving the RRC connection configuration message, the terminal enters the RRC connection mode.
- the terminal sends an RRC Connection Setup Complete message used to confirm successful completion of RRC connection establishment to the network (S530).
- RRC connection reconfiguration is used to modify an RRC connection. It is used to establish / modify / release RBs, perform handovers, and set up / modify / release measurements.
- the network sends an RRC connection reconfiguration message for modifying the RRC connection to the terminal (S610).
- the UE sends an RRC connection reconfiguration complete message used to confirm successful completion of the RRC connection reconfiguration to the network (S620).
- PLMN public land mobile network
- PLMN is a network deployed and operated by mobile network operators. Each mobile network operator runs one or more PLMNs. Each PLMN may be identified by a mobile country code (MCC) and a mobile network code (MCC). The PLMN information of the cell is included in the system information and broadcasted.
- MCC mobile country code
- MCC mobile network code
- PLMN selection In PLMN selection, cell selection and cell reselection, various types of PLMNs may be considered by the terminal.
- HPLMN Home PLMN
- MCC Mobility Management Entity
- Equivalent HPLMN A PLMN that is equivalent to an HPLMN.
- Registered PLMN A PLMN that has successfully completed location registration.
- ELMN Equivalent PLMN
- Each mobile service consumer subscribes to HPLMN.
- HPLMN When a general service is provided to a terminal by HPLMN or EHPLMN, the terminal is not in a roaming state.
- a service is provided to a terminal by a PLMN other than HPLMN / EHPLMN, the terminal is in a roaming state, and the PLMN is called a VPLMN (Visited PLMN).
- PLMN public land mobile network
- PLMN is a network deployed or operated by a mobile network operator. Each mobile network operator operates one or more PLMNs. Each PLMN may be identified by a mobile country code (MCC) and a mobile network code (MCN). The PLMN information of the cell is included in the system information and broadcasted.
- MCC mobile country code
- MN mobile network code
- the terminal attempts to register the selected PLMN. If the registration is successful, the selected PLMN becomes a registered PLMN (RPLMN).
- the network may signal the PLMN list to the UE, which may consider PLMNs included in the PLMN list as PLMNs such as RPLMNs.
- the terminal registered in the network should be reachable by the network at all times. If the terminal is in the ECM-CONNECTED state (same as RRC connected state), the network recognizes that the terminal is receiving the service. However, when the terminal is in the ECM-IDLE state (same as the RRC idle state), the situation of the terminal is not valid in the eNB but is stored in the MME. In this case, the location of the UE in the ECM-IDLE state is known only to the MME as granularity of the list of tracking areas (TAs). A single TA is identified by a tracking area identity (TAI) consisting of the PLMN identifier to which the TA belongs and a tracking area code (TAC) that uniquely represents the TA within the PLMN.
- TAI tracking area identity
- TAC tracking area code
- the UE selects a cell having a signal quality and characteristics capable of receiving an appropriate service from among cells provided by the selected PLMN.
- the terminal selects / reselects a cell of appropriate quality and performs procedures for receiving service.
- the UE in the RRC idle state should always select a cell of appropriate quality and prepare to receive service through this cell. For example, a terminal that has just been powered on must select a cell of appropriate quality to register with the network. When the terminal in the RRC connected state enters the RRC idle state, the terminal should select a cell to stay in the RRC idle state. As such, the process of selecting a cell satisfying a certain condition in order for the terminal to stay in a service standby state such as an RRC idle state is called cell selection.
- the cell selection is performed in a state in which the UE does not currently determine a cell to stay in the RRC idle state, it is most important to select the cell as soon as possible. Therefore, if the cell provides a radio signal quality of a predetermined criterion or more, even if this cell is not the cell providing the best radio signal quality to the terminal, it may be selected during the cell selection process of the terminal.
- an initial cell selection process in which the terminal does not have prior information on the radio channel. Accordingly, the terminal searches all radio channels to find an appropriate cell. In each channel, the terminal finds the strongest cell. Thereafter, the terminal selects a corresponding cell if it finds a suitable cell that satisfies a cell selection criterion.
- the terminal may select the cell by using the stored information or by using the information broadcast in the cell.
- cell selection can be faster than the initial cell selection process.
- the UE selects a corresponding cell if it finds a cell that satisfies the cell selection criteria. If a suitable cell that satisfies the cell selection criteria is not found through this process, the UE performs an initial cell selection process.
- the terminal After the terminal selects a cell through a cell selection process, the strength or quality of a signal between the terminal and the base station may change due to a change in mobility or a wireless environment of the terminal. Therefore, if the quality of the selected cell is degraded, the terminal may select another cell that provides better quality. When reselecting a cell in this way, a cell that generally provides better signal quality than the currently selected cell is selected. This process is called cell reselection.
- the cell reselection process has a basic purpose in selecting a cell that generally provides the best quality to a terminal in view of the quality of a radio signal.
- the network may determine the priority for each frequency and notify the terminal. Upon receiving this priority, the UE considers this priority prior to the radio signal quality criteria in the cell reselection process.
- a method of selecting or reselecting a cell according to a signal characteristic of a wireless environment In selecting a cell for reselection when reselecting a cell, the following cell reselection is performed according to a cell's RAT and frequency characteristics. There may be a method of selection.
- Intra-frequency cell reselection Reselection of a cell having a center-frequency equal to the RAT, such as a cell where the UE is camping
- Inter-frequency cell reselection Reselects a cell having a center frequency different from that of the same RAT as the cell camping
- Inter-RAT cell reselection UE reselects a cell using a RAT different from the camping RAT
- the UE measures the quality of a serving cell and a neighboring cell for cell reselection.
- cell reselection is performed based on cell reselection criteria.
- the cell reselection criteria have the following characteristics with respect to serving cell and neighbor cell measurements.
- Intra-frequency cell reselection is basically based on ranking.
- Ranking is an operation of defining index values for cell reselection evaluation and using the index values to order the cells in the order of the index values.
- the cell with the best indicator is often called the best ranked cell.
- the cell index value is a value obtained by applying a frequency offset or a cell offset as necessary based on the value measured by the terminal for the corresponding cell.
- Inter-frequency cell reselection is based on the frequency priority provided by the network.
- the terminal attempts to camp on the frequency with the highest frequency priority.
- the network may provide the priorities to be commonly applied to the terminals in the cell or provide the frequency priority through broadcast signaling, or may provide the priority for each frequency for each terminal through dedicated signaling.
- the cell reselection priority provided through broadcast signaling may be referred to as common priority, and the cell reselection priority set by the network for each terminal may be referred to as a dedicated priority.
- the terminal may also receive a validity time associated with the dedicated priority.
- the terminal starts a validity timer set to the validity time received together.
- the terminal applies the dedicated priority in the RRC idle mode while the validity timer is running.
- the validity timer expires, the terminal discards the dedicated priority and applies the public priority again.
- the network may provide the UE with parameters (for example, frequency-specific offset) used for cell reselection for each frequency.
- the network may provide the UE with a neighboring cell list (NCL) used for cell reselection to the UE.
- NCL neighboring cell list
- This NCL contains cell-specific parameters (eg cell-specific offsets) used for cell reselection.
- the network may provide the UE with a cell reselection prohibition list (black list) used for cell reselection to the UE.
- the UE does not perform cell reselection for a cell included in the prohibition list.
- the ranking criterion used to prioritize the cells is defined as in Equation 1.
- R s is the ranking indicator of the serving cell
- R n is the ranking indicator of the neighbor cell
- Q meas s is the quality value measured by the UE for the serving cell
- Q meas n is the quality measured by the UE for the neighbor cell
- Q hyst is a hysteresis value for ranking
- Q offset is an offset between two cells.
- the terminal may alternately select two cells.
- Q hyst is a parameter for giving hysteresis in cell reselection to prevent the UE from reselecting two cells alternately.
- the UE measures R s of the serving cell and R n of the neighboring cell according to the above equation, considers the cell having the highest ranking indicator value as the best ranked cell, and reselects the cell.
- the quality of the cell serves as the most important criterion in cell reselection. If the reselected cell is not a normal cell, the terminal excludes the frequency or the corresponding cell from the cell reselection target.
- RLM Radio Link Monitoring
- the terminal monitors the downlink quality based on a cell-specific reference signal to detect the downlink radio link quality of the PCell.
- the UE estimates the downlink radio link quality for PCell downlink radio link quality monitoring purposes and compares it with thresholds Qout and Qin.
- the threshold Qout is defined as the level at which the downlink radio link cannot be stably received, which corresponds to a 10% block error rate of hypothetical PDCCH transmission in consideration of the PDFICH error.
- the threshold Qin is defined as a downlink radio link quality level that can be received more stably than the level of Qout, which corresponds to a 2% block error rate of virtual PDCCH transmission in consideration of PCFICH errors.
- RLF Radio Link Failure
- the UE continuously measures to maintain the quality of the radio link with the serving cell receiving the service.
- the terminal determines whether communication is impossible in the current situation due to deterioration of the quality of the radio link with the serving cell. If the quality of the serving cell is so low that communication is almost impossible, the terminal determines the current situation as a radio connection failure.
- the UE abandons communication with the current serving cell, selects a new cell through a cell selection (or cell reselection) procedure, and reestablishes an RRC connection to the new cell (RRC connection re). -establishment).
- the UE determines that there is a serious problem in the downlink communication quality based on the radio quality measurement result of the physical layer of the UE (when it is determined that the PCell quality is low during the RLM)
- FIG. 7 is a diagram illustrating a RRC connection reestablishment procedure.
- the terminal stops use of all radio bearers which have been set except for Signaling Radio Bearer # 0 (SRB 0) and initializes various sublayers of an access stratum (AS) (S710).
- SRB 0 Signaling Radio Bearer # 0
- AS access stratum
- each sublayer and physical layer are set to a default configuration.
- the UE maintains an RRC connection state.
- the UE performs a cell selection procedure for performing an RRC connection reconfiguration procedure (S720).
- the cell selection procedure of the RRC connection reestablishment procedure may be performed in the same manner as the cell selection procedure performed by the UE in the RRC idle state, although the UE maintains the RRC connection state.
- the terminal After performing the cell selection procedure, the terminal checks the system information of the corresponding cell to determine whether the corresponding cell is a suitable cell (S730). If it is determined that the selected cell is an appropriate E-UTRAN cell, the terminal transmits an RRC connection reestablishment request message to the cell (S740).
- the RRC connection re-establishment procedure is stopped, the terminal is in the RRC idle state Enter (S750).
- the terminal may be implemented to complete the confirmation of the appropriateness of the cell within a limited time through the cell selection procedure and the reception of system information of the selected cell.
- the UE may drive a timer as the RRC connection reestablishment procedure is initiated.
- the timer may be stopped when it is determined that the terminal has selected a suitable cell. If the timer expires, the UE may consider that the RRC connection reestablishment procedure has failed and may enter the RRC idle state.
- This timer is referred to hereinafter as a radio link failure timer.
- a timer named T311 may be used as a radio link failure timer.
- the terminal may obtain the setting value of this timer from the system information of the serving cell.
- the cell When the RRC connection reestablishment request message is received from the terminal and the request is accepted, the cell transmits an RRC connection reestablishment message to the terminal.
- the UE Upon receiving the RRC connection reestablishment message from the cell, the UE reconfigures the PDCP sublayer and the RLC sublayer for SRB1. In addition, it recalculates various key values related to security setting and reconfigures the PDCP sublayer responsible for security with newly calculated security key values. Through this, SRB 1 between the UE and the cell is opened and an RRC control message can be exchanged. The terminal completes the resumption of SRB1 and transmits an RRC connection reestablishment complete message indicating that the RRC connection reestablishment procedure is completed to the cell (S760).
- the cell transmits an RRC connection reestablishment reject message to the terminal.
- the cell and the terminal performs the RRC connection reestablishment procedure.
- the UE recovers the state before performing the RRC connection reestablishment procedure and guarantees the continuity of the service to the maximum.
- the UE reports this failure event to the network when an RLF occurs or a handover failure occurs in order to support Mobility Robustness Optimization (MRO) of the network.
- MRO Mobility Robustness Optimization
- the UE may provide an RLF report to the eNB.
- Radio measurements included in the RLF report can be used as potential reasons for failure to identify coverage problems. This information can be used to exclude such events from the MRO evaluation of intra-LTE mobility connection failures and to write those events as input to other algorithms.
- the UE may generate a valid RLF report for the eNB after reconnecting in the idle mode. For this purpose, the UE stores the latest RLF or handover failure related information, and for 48 hours after the RLF report is retrieved by the network or after the RLF or handover failure is detected, the RRC connection ( Re-establishment and handover may indicate to the LTE cell that the RLF report is valid.
- the UE maintains the information during state transition and RAT change, and indicates that the RLF report is valid again after returning to the LTE RAT.
- the validity of the RLF report in the RRC connection establishment procedure indicates that the UE has been interrupted such as a connection failure and that the RLF report due to this failure has not yet been delivered to the network.
- the RLF report from the terminal includes the following information.
- E-CGI of the target cell of the last cell in case of RRL or handover that provided a service to the terminal. If the E-CGI is unknown, PCI and frequency information is used instead.
- E-CGI of the cell that serviced the terminal when message 7 (RRC connection reset) was received by the terminal for example, at the last handover initialization.
- the eNB receiving the RLF failure from the terminal may forward the report to the eNB that provided the service to the terminal before the reported connection failure.
- Radio measurements included in the RLF report can be used to identify coverage issues as a potential cause of radio link failure. This information can be used to exclude these events from the MRO assessment of intra-LTE mobility connection failures and send them back as input to other algorithms.
- multimedia broadcast and multicast service (MBMS) will be described in detail.
- the transport channel MCH channel for the MBMS may be mapped to the logical channel MCCH channel or MTCH channel.
- the MCCH channel transmits MBMS related RRC messages, and the MTCH channel carries traffic of a specific MBMS service.
- MBSFN Single Frequency Network
- the UE may receive a plurality of MCCH channels.
- the PDCCH channel transmits an MBMS Radio Network Temporary Identity (M-RNTI) and an indicator indicating a specific MCCH channel.
- M-RNTI MBMS Radio Network Temporary Identity
- the UE supporting the MBMS may receive the M-RNTI and the MCCH indicator through the PDCCH channel, determine that the MBMS related RRC message has been changed in the specific MCCH channel, and receive the specific MCCH channel.
- the RRC message of the MCCH channel can be changed at every change cycle, and is repeatedly broadcasted at every repetition cycle.
- the UE may receive a dedicated service. For example, a user may watch a TV through his / her own smartphone, MBMS, and use the smartphone to chat using an instant messaging (IM) service such as MSN or Skype.
- IM instant messaging
- MBMS is provided through MTCH received by several terminals together, and services provided to each terminal individually, such as IM service, will be provided through a dedicated bearer such as DCCH or DTCH.
- some base stations can use multiple frequencies at the same time.
- the network may select one of several frequencies to provide MBMS only at that frequency and provide a dedicated bearer to each terminal at all frequencies.
- the terminal when a terminal that has received a service using a dedicated bearer at a frequency where no MBMS is provided, the terminal should be handed over to a frequency where the MBMS is provided, when the terminal wants to receive the MBMS.
- the terminal transmits an MBMS interest indication to the base station. That is, when the terminal wants to receive the MBMS, the terminal transmits an MBMS interest indication to the base station, and when the base station receives the indication, the terminal recognizes that the terminal wants to receive the MBMS and moves the terminal to the frequency at which the MBMS is provided. Let's do it.
- the MBMS interest indicator refers to information that the terminal wants to receive the MBMS, and additionally includes information on which frequency it wants to move to.
- the UE may select a cell on the frequency where the MBMS is provided as a target cell through inter-frequency cell reselection to the frequency where the MBMS is provided. Through this, the UE may access the corresponding cell and receive the MBMS when the cell provides the MBMS. In order for the UE to select a cell on the frequency where the MBMS can be provided, the highest priority may be applied to the frequency. A cell reselection method related to this will be described in detail with reference to FIG. 8.
- FIG. 8 is a diagram illustrating an example of cell reselection performed by a terminal related to an MBMS.
- a terminal receiving an MBMS on a specific frequency or interested in receiving an MBMS applies the highest priority to a corresponding frequency in performing cell reselection.
- the UE may move to the cell providing the MBMS and receive the MBMS by performing cell reselection using the frequency priority information reset to the highest priority instead of the frequency priority signaled by the network.
- terminal 1 is a terminal that is receiving or is interested in receiving an MBMS
- terminal 2 is a terminal that is not.
- cells 1, 2, and 3 are operating at frequency A
- cells 4, 5, and 6 are operating at frequency B.
- cells 1 and 2, cells 3 and 4, and cells 5 and 6 each have the same coverage.
- the priority for frequency A signaled by the network is '3' and the priority for frequency B is '5'.
- Terminal 1 approaches cell 1 and receives MBMS from cell 1.
- UE 1 is out of coverage of cell 1
- a new target cell is determined by cell reselection.
- Terminal 1 is a terminal that has been provided with the MBMS, and performs cell reselection by applying the highest priority to frequency A, which is the frequency at which the MBMS is provided. Accordingly, the terminal 1 determines the cell 2 as the target cell and approaches the cell 2 (S811).
- the cell reselection is performed by applying the highest priority to the frequency A. Accordingly, the terminal 1 determines the cell 3 as the target cell and approaches the cell 3 (S812).
- the terminal 2 accesses the cell 4 and receives a service from the cell 4.
- a new target cell is determined by cell reselection. Since the terminal 2 is not associated with the MBMS, the terminal 2 performs cell reselection by applying the frequency priority signaled from the network. Accordingly, the terminal may determine cell 5 operating at frequency B having priority 5 as a target cell instead of cell 2 operating at frequency A having priority 3 and approach cell 5 (S821). Subsequently, if the UE leaves the coverage of cell 5, it may determine cell 6 as a target cell based on the signaled priority and approach cell 6 (S822).
- the terminal 1 provided with the MBMS selects the cell reselection by applying the highest priority to a specific frequency provided by the MBMS, and thus may access the cell providing the MBMS.
- the UE when the MBMS is actually provided as described above, or if the highest priority is applied to the cell reselection for a specific frequency estimated that the MBMS will be provided by the UE, the UE has a low priority and does not provide the MBM.
- the problem of determining the target cell may occur.
- the UE since cell 2 does not provide MBMS on frequency A but highest priority is applied to frequency A, the UE selects cell 2 as a target cell and approaches.
- the terminals may access a cell that does not provide an actual MBMS, which may cause a problem that causes unnecessary congestion for the cell.
- the cell may stop providing the MBMS to convert the MBMS-related traffic into unicast traffic.
- the UE may perform cell reselection by continuously applying the highest priority to the frequency of the corresponding cell and may continuously access the corresponding frequency.
- the corresponding cell may experience a problem of increased traffic to the terminals. This may result in opposition to the operation of the cell base station and / or network operation to abort the MBMS to mitigate cell congestion.
- FIG. 9 is a flowchart illustrating cell reselection according to an embodiment of the present invention.
- the terminal determines whether to apply the highest priority to a specific frequency in cell reselection (S910).
- the highest priority may mean higher priority than the priority signaled by the network.
- the specific frequency at which the UE may be provided with the highest priority may be the frequency at which the MBMS is provided or is expected to be provided. Determining whether to apply the highest priority to the frequency may be implemented by checking whether system information required for obtaining MBMS control information is broadcast.
- the system information required for obtaining the MBMS control information may be SIB 13 among system information broadcast by the cell. Accordingly, the UE may determine whether SIB 13 is being broadcast by a neighbor cell, and if SIB 13 is being broadcast, may determine to apply the highest priority to a corresponding frequency.
- the highest priority may be applied to the corresponding frequency (S920).
- the priority signaled by the network may be applied to the corresponding frequency (S930).
- the UE may perform cell reselection based on the applied priority and access the selected target cell (S940).
- FIG. 10 is a flowchart illustrating an example of a cell reselection method according to an embodiment of the present invention.
- the terminal performs cell reselection evaluation for cell 1.
- the terminal receives the system information from the cell 1, but receives the SIB 13 required to obtain the MBMS control information (S1011).
- the UE may determine that SIB 13 is broadcast from Cell 1 and may determine to apply the highest priority to frequency A.
- the terminal applies the highest priority to the frequency A (S1012), and performs cell reselection based on the applied priority. Accordingly, the terminal may reselect cell 1 and camp on cell 1 (S1013).
- the UE may move out of the coverage of cell 1 and approach the coverage of cells 2 and 4 (S1021). Accordingly, the terminal performs cell reselection evaluation on cells 2 and 4 (S1022).
- Cell 2 may not broadcast SIB 13 because it does not provide MBMS.
- the terminal receives system information from cell 2 but does not receive SIB 13 required to obtain MBMS control information (S1023). Accordingly, the terminal applies the priority signaled from the network to the frequency A and the frequency B (S1024).
- the terminal performs cell reselection based on the applied priority. Since the priority for frequency A is '3' and the priority for frequency B is '5', the terminal may reselect cell 4 operating on frequency B of higher priority and camp on cell 4. There is (S1025).
- the UE may move out of the coverage of cell 4 and approach the coverage of cell 3 (S1031). Accordingly, the terminal performs cell reselection evaluation on cell 3 (S1032).
- the terminal Since the terminal has been previously provided with the MBMS and is a terminal interested in receiving the MBMS, it may be determined whether the cell 3 is broadcasting the SIB 13 necessary for obtaining the MBMS control information. Accordingly, the terminal receives the system information from the cell 3 from the cell 3, but receives the SIB 13 required to obtain the MBMS control information (S1033). The UE may determine that SIB 13 is broadcast from Cell 1 and may determine to apply the highest priority to frequency A. FIG.
- the terminal applies the highest priority to the frequency A (S1034), and performs cell reselection based on the applied priority. Accordingly, the terminal may reselect cell 3 and camp on cell 3 (S1035).
- FIG. 11 is a diagram illustrating an example of terminal movement when a cell reselection method according to an embodiment of the present invention is applied.
- terminal 1 and terminal 2 are receiving the MBMS or are interested in receiving the MBMS.
- cells 1, 2, and 3 are operating at frequency A
- cells 4, 5, and 6 are operating at frequency B.
- cells 1 and 2, cells 3 and 4, and cells 5 and 6 each have the same coverage.
- the priority for frequency A signaled by the network is '3' and the priority for frequency B is '5'.
- UE 1 moves based on the existing cell reselection method
- UE 1 moves based on the MBMS-based cell reselection method proposed in the embodiment of the present invention.
- UE 1 approaches cell 1 and receives MBMS from cell 1.
- a new target cell is determined by cell reselection. Since UE 1 moves based on the existing cell reselection scheme, the first priority is applied to the frequency A of the cell 2 without determining whether the cell 2 provides the actual MBMS. Accordingly, the terminal 1 determines the cell 2 as the target cell and approaches the cell 2 (S1111).
- cell reselection is performed by applying the highest priority to frequency A. Therefore, the terminal 1 determines the cell 3 as the target cell and approaches the cell 3 (S1112).
- Terminal 2 approaches cell 1 and receives MBMS from cell 1.
- UE 1 When UE 1 is out of coverage of cell 1, a new target cell is determined by cell reselection. Since UE 2 moves based on the cell reselection scheme proposed in the present invention, it is possible to determine whether MBMS is substantially provided at frequency A of cell 2. To this end, the UE determines whether SIB 13 necessary for obtaining MBMS control information is being broadcast from cell 2. If it is determined that cell 2 does not broadcast SIB 13, the terminal may apply the priorities signaled by the network to frequency A of cell 2 and frequency B of cell 5, respectively. Accordingly, the terminal may determine cell 5 operating at frequency B having priority 5 as the target cell instead of cell 2 operating at frequency A having priority 3 and approach cell 5 (S1121).
- the UE when the UE enters the coverage of Cell 3 and Cell 6 out of the coverage of Cell 5, it may be determined whether Cell 3 operating at frequency A, which is expected to provide MBMS service, substantially provides MBMS. To this end, the UE determines whether SIB 13 is being broadcast from cell 3. If it is determined that cell 3 does not broadcast SIB 13, the terminal may apply the highest priority to frequency A of cell 3. Accordingly, the terminal determines cell 3 as the target cell and accesses cell 3 (S1122).
- the UE applies the highest priority to the frequency until the specific condition is satisfied. May not be considered.
- the terminal 2 confirms that SIB 13 is not broadcasted at the frequency A of the cell 2 and selects and accesses the cell 5 operating at the frequency B through cell reselection, when a specific condition is satisfied. Up to frequency A application may not be considered. Specific conditions may be as follows.
- the terminal may start the formulation timer when it is determined that the MBMS is not provided at the frequency of a specific cell, and may reset the formulation timer when it is determined that the MBMS is provided at the corresponding frequency of another cell. have.
- the terminal may determine whether to apply the highest priority to the corresponding frequency, and may apply the priority according to the determination result.
- the UE can be prevented from actually accessing the cell of the frequency where the MBMS is not provided.
- the terminal may determine whether the MBMS is actually provided in the cell and may not apply the highest priority to the frequency of the cell.
- the UEs can select and approach another cell on a high priority frequency instead of a cell having a low frequency priority without providing an MBMS.
- the terminal may avoid access to a crowded cell, thereby receiving a more efficient service, and the network may provide an efficient service through appropriate load balancing.
- FIG. 12 is a block diagram illustrating a wireless device in which an embodiment of the present invention is implemented. This apparatus may be implemented to perform the cell reselection method according to the embodiment of the present invention described above with reference to FIGS.
- the wireless device 1200 includes a processor 1210, a memory 1220, and an RF unit 1230.
- the processor 1210 implements the proposed functions, processes, and / or methods.
- the processor 1210 may be configured to determine whether to apply the highest priority for a particular frequency.
- the processor 1210 may be configured to determine whether SIB 13 is being broadcast at a corresponding frequency to determine whether to apply the highest priority.
- the processor 1210 may be configured to perform cell reselection by applying a highest priority or a priority signaled by a network to a specific frequency according to the determination result.
- the processor 1210 may be configured to implement embodiments of the present invention described above with reference to the drawings.
- the RF unit 1230 is connected to the processor 1210 to transmit and receive a radio signal.
- the processor may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices.
- the memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and / or other storage device.
- the RF unit may include a baseband circuit for processing a radio signal.
- the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function.
- the module may be stored in memory and executed by a processor.
- the memory may be internal or external to the processor and may be coupled to the processor by various well known means.
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Abstract
Description
Claims (16)
- 무선 통신 시스템에서 단말에 의하여 수행되는 셀 재선택 방법에 있어서,이웃 셀로부터 MBMS(Multicast Broadcast Multimedia Service)를 위한 시스템 정보가 브로드캐스트되는지 여부를 판단하고; 및상기 MBMS를 위한 시스템 정보가 브로드캐스트 되면, 상기 이웃 셀의 주파수에 최우선순위를 적용하여 셀 재선택을 수행하는 것;을 포함함을 특징으로 하는 셀 재선택 방법.
- 제 1항에 있어서, 상기 MBMS를 위한 시스템 정보는 상기 이웃 셀로부터 방송되는 시스템 정보의 SIB(System Information Block) 13인 것을 특징으로 하는 셀 재선택 방법.
- 제 2항에 있어서, 상기 방법은상기 MBMS를 위한 시스템 정보가 브로드캐스트되지 않으면, 상기 이웃 셀의 주파수에 시그널링된 우선순위를 적용하여 셀 재선택을 수행하는 것;을 더 포함함을 특징으로 하는 셀 재선택 방법.
- 제 3항에 있어서,상기 단말은 MBMS를 수신하고 있거나 또는 MBMS 서비스 수신에 관심이 있는 것을 특징으로 하는 셀 재선택 방법.
- 제 3항에 있어서, 상기 방법은상기 단말이 상기 시그널링된 우선순위를 적용하여 셀 재선택을 수행한 결과 상기 주파수와 다른 주파수 상의 셀로 이동하면, 상기 주파수에 대하여 상기 최우선순위를 적용하지 않는 시간 구간과 관련된 제제 타이머(prohibit timer)를 개시하는 것을 더 포함함을 특징으로 하는 셀 재선택 방법.
- 제 5항에 있어서, 상기 방법은,상기 주파수에서 MBMS 서비스가 제공되면, 상기 제제 타이머를 리셋시키는 것을 더 포함함을 특징으로 하는 셀 재선택 방법.
- 제 5항에 있어서, 상기 방법은,상기 단말의 서빙 셀이 변경되면, 상기 제제 타이머를 리셋시키는 것을 더 포함함을 특징으로 하는 셀 재선택 방법.
- 제 5항에 있어서, 상기 방법은,트래킹 영역(tracking area)가 변경되면, 상기 제제 타이머를 리셋시키는 것을 더 포함함을 특징으로 하는 셀 재선택 방법.
- 무선 통신 시스템에서 운영되는 무선 장치에 있어서, 상기 무선 장치는,무선 신호를 송신 및 수신하는 RF(Radio Frequency) 부; 및상기 RF부와 기능적으로 결합하여 동작하는 프로세서를 포함하되, 상기 프로세서는,이웃 셀로부터 MBMS(Multicast Broadcast Multimedia Service)를 위한 시스템 정보가 브로드캐스트되는지 여부를 판단하고,상기 MBMS를 위한 시스템 정보가 브로드캐스트 되면, 상기 이웃 셀의 주파수에 최우선순위를 적용하여 셀 재선택을 수행하도록 설정된 무선 장치.
- 제 9항에 있어서, 상기 MBMS를 위한 시스템 정보는 상기 이웃 셀로부터 방송되는 시스템 정보의 SIB(System Information Block) 13인 것을 특징으로 하는 무선 장치.
- 제 10항에 있어서, 상기 프로세서는상기 MBMS를 위한 시스템 정보가 브로드캐스트되지 않으면, 상기 이웃 셀의 주파수에 시그널링된 우선순위를 적용하여 셀 재선택을 수행하도록 설정된 것을 특징으로 하는 무선 장치.
- 제 11항에 있어서,상기 무선 장치는 MBMS를 수신하고 있거나 또는 MBMS 서비스 수신에 관심이 있는 것을 특징으로 하는 무선 장치.
- 제 11항에 있어서, 상기 프로세서는상기 무선 장치가 상기 시그널링된 우선순위를 적용하여 셀 재선택을 수행한 결과 상기 주파수와 다른 주파수 상의 셀로 이동하면, 상기 주파수에 대하여 상기 최우선순위를 적용하지 않는 시간 구간과 관련된 제제 타이머(prohibit timer)를 개시하도록 설정된 것을 특징으로 하는 무선 장치.
- 제 13항에 있어서, 상기 프로세서는상기 주파수에서 MBMS 서비스가 제공됨이 감지되면, 상기 제제 타이머를 리셋시키도록 설정된 것을 특징으로 하는 무선 장치.
- 제 13항에 있어서, 상기 프로세서는상기 무선 장치의 서빙 셀이 변경되면, 상기 제제 타이머를 리셋시키도록 설정된 것을 특징으로 하는 무선 장치.
- 제 13항에 있어서, 상기 프로세서는트래킹 영역(tracking area)가 변경되면, 상기 제제 타이머를 리셋시키도록 설정된 것을 특징으로 하는 무선 장치.
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US14/389,962 US9955399B2 (en) | 2012-04-05 | 2013-04-04 | Method for reselecting MBMS-based cells in wireless communication systems, and apparatus for supporting same |
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US20150071157A1 (en) | 2015-03-12 |
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