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WO2018062786A1 - Procédé et appareil permettant de commander un srb - Google Patents

Procédé et appareil permettant de commander un srb Download PDF

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Publication number
WO2018062786A1
WO2018062786A1 PCT/KR2017/010535 KR2017010535W WO2018062786A1 WO 2018062786 A1 WO2018062786 A1 WO 2018062786A1 KR 2017010535 W KR2017010535 W KR 2017010535W WO 2018062786 A1 WO2018062786 A1 WO 2018062786A1
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WO
WIPO (PCT)
Prior art keywords
srb
base station
terminal
cell
rrc
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Ceased
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PCT/KR2017/010535
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English (en)
Korean (ko)
Inventor
이영대
김상원
이재욱
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LG Electronics Inc
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LG Electronics Inc
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Priority to US16/333,418 priority Critical patent/US11076442B2/en
Publication of WO2018062786A1 publication Critical patent/WO2018062786A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/15—Setup of multiple wireless link connections
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/19—Connection re-establishment

Definitions

  • the present invention relates to a wireless communication system, and more particularly, to a method for a terminal to control a signaling radio bearer (SRB) and an apparatus supporting the same.
  • SRB signaling radio bearer
  • a 5G communication system or a pre-5G communication system is called a system after a 4G network (beyond 4G network) or after a long term evolution (LTE) system (post LTE).
  • the terminal 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 Link Failure (RLF). If the radio link failure is determined, the UE abandons communication maintenance with the current serving cell, selects a new cell through a cell selection (or cell reselection) procedure, and attempts to reestablish RRC connection to the new cell.
  • RLF Radio Link Failure
  • the reliability of the RRC connection is important. If a connection failure occurs, not only the terminal but also the base station cannot use a data radio bearer (DRB), and thus data transmission is impossible. For example, while the RRC connection reestablishment procedure is in progress, the UE cannot perform data transmission / reception. Therefore, in order to secure the reliability of the RRC connection, a method for controlling a signaling radio bearer (SRB) by the terminal and an apparatus supporting the same need to be proposed.
  • SRB signaling radio bearer
  • a method for controlling a signaling radio bearer (SRB) by a terminal in a wireless communication system includes: establishing a radio resource control (RRC) connection with a first base station and establishing a first SRB; Establishing a second SRB with a second base station, wherein the second SRB is in a suspended state; And if the quality of the cell at the first base station is worse than a first threshold, resuming the suspended second SRB.
  • RRC radio resource control
  • the method may further include suspending the first SRB.
  • the method may further include resuming the suspended second SRB if the quality of the cell at the second base station is better than a second threshold.
  • the method may further include resuming the suspended second SRB when a radio link failure related timer or a handover failure related timer is started.
  • the method may further include resuming the suspended second SRB when a re-establishment procedure for the RRC connection is initiated.
  • the method may further include resuming the suspended second SRB when the terminal determines to suspend the first SRB.
  • the second SRB may be a temporary SRB.
  • the first base station may be a base station in which an RRC entity for the terminal is located
  • the second base station may be a base station in which an RRC entity for the terminal is not located.
  • a method for controlling a signaling radio bearer (SRB) by a terminal in a wireless communication system comprises: establishing a radio resource control (RRC) connection and a first SRB with a first base station, wherein the first SRB is in a suspended state; Establishing a second base station and a second SRB; And if the quality of the cell at the first base station is better than a first threshold, resuming the suspended first SRB.
  • RRC radio resource control
  • the method may further include suspending the second SRB.
  • the method may further include resuming the suspended first SRB if the quality of the cell at the second base station is worse than a second threshold.
  • the method may further include resuming the suspended first SRB when the radio link failure related timer or the handover failure related timer is stopped.
  • the method may further include resuming the suspended first SRB when the terminal determines to suspend the second SRB.
  • the first base station may be a base station in which an RRC entity for the terminal is located
  • the second base station may be a base station in which an RRC entity for the terminal is not located.
  • a terminal for controlling a signaling radio bearer (SRB) in a wireless communication system includes a memory; Transceiver; And a processor connecting the memory and the transceiver, wherein the processor establishes a radio resource control (RRC) connection and a first SRB and a second base station and a second SRB.
  • RRC radio resource control
  • the SRB is in a suspended state, and may be configured to resume the suspended second SRB if the quality of the cell at the first base station is worse than a first threshold.
  • the reliability of the RRC connection can be improved.
  • FIG. 1 shows a structure of an LTE system.
  • FIG. 2 shows an air interface protocol of an LTE system for a control plane.
  • FIG 3 shows an air interface protocol of an LTE system for a user plane.
  • FIG. 7 illustrates a procedure of controlling an SRB by a terminal according to an embodiment of the present invention.
  • FIG. 8 illustrates a procedure of controlling an SRB by a terminal according to an embodiment of the present invention.
  • FIG 9 illustrates an example in which a temporary SRB is set according to an embodiment of the present invention.
  • FIG. 10 illustrates a method for maintaining an RRC connection through a temporary SRB and a procedure for a UE to reestablish an RRC connection when a connection fails according to an embodiment of the present invention.
  • FIG. 11 is a block diagram illustrating a method of controlling an SRB by a terminal according to an embodiment of the present invention.
  • FIG. 12 is a block diagram illustrating a method of controlling an SRB by a terminal according to an embodiment of the present invention.
  • FIG. 13 is a block diagram of a wireless communication system in which an embodiment of the present invention is implemented.
  • CDMA code division multiple access
  • FDMA frequency division multiple access
  • TDMA time division multiple access
  • OFDMA orthogonal frequency division multiple access
  • SC-FDMA single carrier frequency division multiple access
  • CDMA may be implemented with a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000.
  • TDMA may be implemented with wireless technologies such as global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM evolution (EDGE).
  • GSM global system for mobile communications
  • GPRS general packet radio service
  • EDGE enhanced data rates for GSM evolution
  • OFDMA may be implemented by wireless technologies such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA), and the like.
  • IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e.
  • UTRA is part of a universal mobile telecommunications system (UMTS).
  • 3rd generation partnership project (3GPP) long term evolution (LTE) is part of evolved UMTS (E-UMTS) using evolved-UMTS terrestrial radio access (E-UTRA), which employs OFDMA in downlink and SC in uplink -FDMA is adopted.
  • LTE-A (advanced) is the evolution of 3GPP LTE.
  • 5G communication system is the evolution of LTE-A.
  • FIG. 1 shows a structure of an LTE system.
  • Communication networks are widely deployed to provide various communication services such as IMS and Voice over internet protocol (VoIP) over packet data.
  • VoIP Voice over internet protocol
  • an LTE system structure includes one or more UEs 10, an evolved-UMTS terrestrial radio access network (E-UTRAN), and an evolved packet core (EPC).
  • the terminal 10 is a communication device moved by a user.
  • 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), and a wireless device.
  • MS mobile station
  • UT user terminal
  • SS subscriber station
  • wireless device a wireless device.
  • the E-UTRAN may include one or more evolved node-eB (eNB) 20, and a plurality of terminals may exist in one cell.
  • the eNB 20 provides an end point of a control plane and a user plane to the terminal.
  • the eNB 20 generally refers to a fixed station communicating with the terminal 10, and may be referred to in other terms such as a base station (BS), a base transceiver system (BTS), an access point, and the like.
  • BS base station
  • BTS base transceiver system
  • One eNB 20 may be arranged per cell. There may be one or more cells within the coverage of the eNB 20.
  • One cell may be configured to have one of bandwidths such as 1.25, 2.5, 5, 10, and 20 MHz to provide downlink (DL) or uplink (UL) transmission service to various terminals. In this case, different cells may be configured to provide different bandwidths.
  • DL means communication from the eNB 20 to the terminal 10
  • UL means communication from the terminal 10 to the eNB 20.
  • the transmitter may be part of the eNB 20 and the receiver may be part of the terminal 10.
  • the transmitter may be part of the terminal 10 and the receiver may be part of the eNB 20.
  • the EPC may include a mobility management entity (MME) that serves as a control plane, and a system architecture evolution (SAE) gateway (S-GW) that serves as a user plane.
  • MME mobility management entity
  • SAE system architecture evolution gateway
  • S-GW gateway
  • the MME / S-GW 30 may be located at the end of the network and is connected to an external network.
  • the MME has information about the access information of the terminal or the capability of the terminal, and this information may be mainly used for mobility management of the terminal.
  • S-GW is a gateway having an E-UTRAN as an endpoint.
  • the MME / S-GW 30 provides the terminal 10 with the endpoint of the session and the mobility management function.
  • the EPC may further include a packet data network (PDN) -gateway (GW).
  • PDN-GW is a gateway with PDN as an endpoint.
  • the MME includes non-access stratum (NAS) signaling to the eNB 20, NAS signaling security, access stratum (AS) security control, inter CN (node network) signaling for mobility between 3GPP access networks, idle mode terminal reachability ( Control and execution of paging retransmission), tracking area list management (for terminals in idle mode and active mode), P-GW and S-GW selection, MME selection for handover with MME change, 2G or 3G 3GPP access Bearer management, including roaming, authentication, and dedicated bearer settings, SGSN (serving GPRS support node) for handover to the network, public warning system (ETWS) and commercial mobile alarm system (PWS) It provides various functions such as CMAS) and message transmission support.
  • NAS non-access stratum
  • AS access stratum
  • inter CN node network
  • MME selection for handover with MME change
  • 2G or 3G 3GPP access Bearer management including roaming, authentication, and dedicated bearer settings
  • SGSN serving GPRS support no
  • S-GW hosts can be based on per-user packet filtering (eg, through deep packet inspection), legal blocking, terminal IP (Internet protocol) address assignment, transport level packing marking in DL, UL / DL service level charging, gating and It provides various functions of class enforcement, DL class enforcement based on APN-AMBR.
  • MME / S-GW 30 is simply represented as a "gateway", which may include both MME and S-GW.
  • An interface for user traffic transmission or control traffic transmission may be used.
  • the terminal 10 and the eNB 20 may be connected by the Uu interface.
  • the eNBs 20 may be interconnected by an X2 interface. Neighboring eNBs 20 may have a mesh network structure by the X2 interface.
  • the eNBs 20 may be connected with the EPC by the S1 interface.
  • the eNBs 20 may be connected to the EPC by the S1-MME interface and may be connected to the S-GW by the S1-U interface.
  • the S1 interface supports a many-to-many-relation between eNB 20 and MME / S-GW 30.
  • the eNB 20 may select for the gateway 30, routing to the gateway 30 during radio resource control (RRC) activation, scheduling and transmission of paging messages, scheduling channel information (BCH), and the like.
  • RRC radio resource control
  • BCH scheduling channel information
  • the gateway 30 may perform paging initiation, LTE idle state management, user plane encryption, SAE bearer control, and encryption and integrity protection functions of NAS signaling in the EPC.
  • FIG. 2 shows an air interface protocol of an LTE system for a control plane.
  • 3 shows an air interface protocol of an LTE system for a user plane.
  • the layer of the air interface protocol between the UE and the E-UTRAN is based on the lower three layers of the open system interconnection (OSI) model, which is well known in communication systems, and includes L1 (first layer), L2 (second layer), and L3 (third layer). Hierarchical).
  • the air interface protocol between the UE and the E-UTRAN may be horizontally divided into a physical layer, a data link layer, and a network layer, and vertically a protocol stack for transmitting control signals.
  • Layers of the radio interface protocol may exist in pairs in the UE and the E-UTRAN, which may be responsible for data transmission of the Uu interface.
  • the physical layer belongs to L1.
  • the physical layer provides an information transmission service to a higher layer through a physical channel.
  • the physical layer is connected to a higher layer of a media access control (MAC) layer through a transport channel.
  • Physical channels are mapped to transport channels.
  • Data may be transmitted between the MAC layer and the physical layer through a transport channel.
  • Data between different physical layers, that is, between the physical layer of the transmitter and the physical layer of the receiver may be transmitted using radio resources through a physical channel.
  • the physical layer may be modulated using an orthogonal frequency division multiplexing (OFDM) scheme, and utilizes time and frequency as radio resources.
  • OFDM orthogonal frequency division multiplexing
  • the physical layer uses several physical control channels.
  • a physical downlink control channel (PDCCH) reports resource allocation of a paging channel (PCH) and a downlink shared channel (DL-SCH), and hybrid automatic repeat request (HARQ) information related to the DL-SCH to the UE.
  • the PDCCH may carry an uplink grant to report to the UE regarding resource allocation of uplink transmission.
  • the physical control format indicator channel (PCFICH) informs the UE of the number of OFDM symbols used for the PDCCH and is transmitted every subframe.
  • a physical hybrid ARQ indicator channel (PHICH) carries a HARQ ACK (non-acknowledgement) / NACK (non-acknowledgement) signal for UL-SCH transmission.
  • a physical uplink control channel (PUCCH) carries UL control information such as HARQ ACK / NACK, a scheduling request, and a CQI for downlink transmission.
  • the physical uplink shared channel (PUSCH) carries an uplink shared channel (UL-SCH).
  • the physical channel includes a plurality of subframes in the time domain and a plurality of subcarriers in the frequency domain.
  • One subframe consists of a plurality of symbols in the time domain.
  • One subframe consists of a plurality of resource blocks (RBs).
  • One resource block is composed of a plurality of symbols and a plurality of subcarriers.
  • each subframe may use specific subcarriers of specific symbols of the corresponding subframe for the PDCCH.
  • the first symbol of the subframe may be used for the PDCCH.
  • the PDCCH may carry dynamically allocated resources, such as a physical resource block (PRB) and modulation and coding schemes (MCS).
  • a transmission time interval (TTI) which is a unit time at which data is transmitted, may be equal to the length of one subframe.
  • One subframe may have a length of 1 ms.
  • a DL transport channel for transmitting data from a network to a UE includes a broadcast channel (BCH) for transmitting system information, a paging channel (PCH) for transmitting a paging message, and a DL-SCH for transmitting user traffic or control signals. And the like.
  • BCH broadcast channel
  • PCH paging channel
  • DL-SCH supports dynamic link adaptation and dynamic / semi-static resource allocation by varying HARQ, modulation, coding and transmit power.
  • the DL-SCH may enable the use of broadcast and beamforming throughout the cell.
  • System information carries one or more system information blocks. All system information blocks can be transmitted in the same period. Traffic or control signals of a multimedia broadcast / multicast service (MBMS) are transmitted through a multicast channel (MCH).
  • MCH multicast channel
  • the UL transport channel for transmitting data from the terminal to the network includes a random access channel (RAC) for transmitting an initial control message, a UL-SCH for transmitting user traffic or a control signal, and the like.
  • the UL-SCH can support dynamic link adaptation due to HARQ and transmit power and potential changes in modulation and coding.
  • the UL-SCH may enable the use of beamforming.
  • RACH is generally used for initial connection to a cell.
  • the MAC layer belonging to L2 provides a service to a radio link control (RLC) layer, which is a higher layer, through a logical channel.
  • RLC radio link control
  • the MAC layer provides a mapping function from a plurality of logical channels to a plurality of transport channels.
  • the MAC layer also provides a logical channel multiplexing function by mapping from multiple logical channels to a single transport channel.
  • the MAC sublayer provides data transfer services on logical channels.
  • the logical channel may be divided into a control channel for information transmission in the control plane and a traffic channel for information transmission in the user plane according to the type of information to be transmitted. That is, a set of logical channel types is defined for other data transfer services provided by the MAC layer.
  • the logical channel is located above the transport channel and mapped to the transport channel.
  • the control channel is used only for conveying information in the control plane.
  • the control channel provided by the MAC layer includes a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), and a dedicated control channel (DCCH).
  • BCCH is a downlink channel for broadcasting system control information.
  • PCCH is a downlink channel used for transmitting paging information and paging a terminal whose cell-level location is not known to the network.
  • CCCH is used by the terminal when there is no RRC connection with the network.
  • MCCH is a one-to-many downlink channel used to transmit MBMS control information from the network to the terminal.
  • DCCH is a one-to-one bidirectional channel used by the terminal for transmitting dedicated control information between the terminal and the network in an RRC connection state.
  • the traffic channel is used only for conveying information in the user plane.
  • the traffic channel provided by the MAC layer includes a dedicated traffic channel (DTCH) and a multicast traffic channel (MTCH).
  • DTCH is used for transmission of user information of one UE in a one-to-one channel and may exist in both uplink and downlink.
  • MTCH is a one-to-many downlink channel for transmitting traffic data from the network to the terminal.
  • the uplink connection between the logical channel and the transport channel includes a DCCH that can be mapped to the UL-SCH, a DTCH that can be mapped to the UL-SCH, and a CCCH that can be mapped to the UL-SCH.
  • the downlink connection between the logical channel and the transport channel is a BCCH that can be mapped to a BCH or DL-SCH, a PCCH that can be mapped to a PCH, a DCCH that can be mapped to a DL-SCH, a DTCH that can be mapped to a DL-SCH, MCCH that can be mapped to MCH and MTCH that can be mapped to MCH.
  • the RLC layer belongs to L2.
  • the function of the RLC layer includes adjusting the size of the data by segmentation / concatenation of the data received from the upper layer in the radio section such that the lower layer is suitable for transmitting data.
  • the RLC layer is divided into three modes: transparent mode (TM), unacknowledged mode (UM) and acknowledged mode (AM). Provides three modes of operation.
  • TM transparent mode
  • UM unacknowledged mode
  • AM acknowledged mode
  • AM RLC provides retransmission through automatic repeat request (ARQ) for reliable data transmission.
  • ARQ automatic repeat request
  • the function of the RLC layer may be implemented as a functional block inside the MAC layer, in which case the RLC layer may not exist.
  • the packet data convergence protocol (PDCP) layer belongs to L2.
  • the PDCP layer introduces an IP packet, such as IPv4 or IPv6, over a relatively low bandwidth air interface to provide header compression that reduces unnecessary control information so that the transmitted data is transmitted efficiently. Header compression improves transmission efficiency in the wireless section by transmitting only the information necessary for the header of the data.
  • the PDCP layer provides security. Security functions include encryption to prevent third party inspection and integrity protection to prevent third party data manipulation.
  • the radio resource control (RRC) layer belongs to L3.
  • the RRC layer at the bottom of L3 is defined only in the control plane.
  • the RRC layer serves to control radio resources between the terminal and the network.
  • the UE and the network exchange RRC messages through the RRC layer.
  • the RRC layer is responsible for the control of logical channels, transport channels and physical channels in connection with the configuration, re-configuration and release of RBs.
  • RB is a logical path provided by L1 and L2 for data transmission between the terminal and the network. That is, RB means a service provided by L2 for data transmission between the UE and the E-UTRAN. Setting up an RB means defining the characteristics of the radio protocol layer and channel to provide a particular service, and determining each specific parameter and method of operation.
  • RBs may be classified into two types: signaling RBs (SRBs) and data RBs (DRBs).
  • SRBs signaling RBs
  • DRBs data RBs
  • the non-access stratum (NAS) layer located above the RRC layer performs functions such as session management and mobility management.
  • the RLC and MAC layers may perform functions such as scheduling, ARQ and HARQ.
  • the RRC layer (ended at the eNB at the network side) may perform functions such as broadcast, paging, RRC connection management, RB control, mobility function, and UE measurement report / control.
  • the NAS control protocol (terminated at the gateway's MME at the network side) may perform functions such as SAE bearer management, authentication, LTE_IDLE mobility handling, paging initiation at LTE_IDLE, and security control for signaling between the terminal and the gateway.
  • the RLC and MAC layer may perform the same function as the function in the control plane.
  • the PDCP layer may perform user plane functions such as header compression, integrity protection and encryption.
  • the terminal sends an RRC connection request message to the network requesting an RRC connection (S410).
  • the network sends an RRC connection setup message in response to the RRC connection request (S420). After receiving the RRC connection setup message, the terminal enters the RRC connection mode.
  • the UE sends an RRC Connection Setup Complete message to the network, which is used to confirm successful completion of RRC connection establishment (S430).
  • RRC connection reset is used to modify an RRC connection. It is used to set / 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 (S510).
  • the UE sends an RRC connection reconfiguration complete message used to confirm successful completion of the RRC connection reconfiguration to the network (S520).
  • the UE stops using all radio bearers which are set except for Signaling Radio Bearer # 0 (SRB 0) and initializes various sublayers of an access stratum (AS) (S610). In addition, each sublayer and physical layer are set to a default configuration. During this process, the UE maintains an RRC connection state.
  • SRB 0 Signaling Radio Bearer # 0
  • AS Access stratum
  • the UE performs a cell selection procedure for performing an RRC connection reestablishment procedure (S620).
  • 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 system information of the corresponding cell to determine whether the corresponding cell is a suitable cell (S630). If it is determined that the selected cell is an appropriate E-UTRAN cell, the UE transmits an RRC connection reestablishment request message to the cell (S640).
  • the RRC connection reestablishment procedure is stopped, the terminal is in the RRC idle state Enter (S650).
  • 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 receiving 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 UE 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 (S660).
  • the cell transmits an RRC connection reestablishment reject message to the terminal.
  • the cell and the terminal perform 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 reliability of the RRC connection is important. If a connection failure occurs, not only the terminal but also the base station cannot use a data radio bearer (DRB), and thus data transmission is impossible.
  • DRB data radio bearer
  • the RRC function supports recovery of an RRC connection by using an RRC connection reestablishment procedure.
  • the UE may perform cell selection and access to the selected cell.
  • the terminal may resume data transmission.
  • it may take time until the RRC connection reestablishment procedure is completed, and data transmission may be impossible during the corresponding time. Due to the interruption time as described above, user plane latency may be surpassed and packet delay may be increased. Therefore, reliable RRC connections are very important to minimize interruption time in connection failure cases.
  • RRC diversity has been regarded as a potential solution for improving mobility robustness. Due to RRC diversity, RLF can be prevented as long as the terminal can maintain a connection with at least one cell. This may prevent the RRC reestablishment procedure from being performed.
  • RRC diversity was not reflected in the LTE standard. In fact, it is also not clear to support RRC diversity when the RRC connection is in good condition. Moreover, various means exist to improve the reliability of RRC message delivery. In LTE, all RRC messages are carried over the MCG. For example, all RRC messages are carried over the MCG regardless of the SRB used in both downlink and uplink. This is also acceptable for LTE / NR interworking and standalone NR as long as the RRC connection is not jeopardized (eg, connection failure case). Thus, a mechanism to improve the reliability of the RRC connection may be needed only in connection failure cases.
  • SRB signaling radio bearer
  • FIG. 7 illustrates a procedure of controlling an SRB by a terminal according to an embodiment of the present invention.
  • the UE may make an RRC connection with the first base station and set up the first base station and the first SRB.
  • the first base station may be a master eNB or a gNB.
  • the first base station may be a base station where an RRC entity for the terminal is located.
  • the first SRB may provide exchange of RRC messages between the RRC entity of the first base station and the RRC entity of the terminal.
  • the first SRB may be one or more.
  • the terminal may set up a radio resource (and radio bearer) with the second base station, and set up the second base station and the second SRB.
  • the second base station may be a secondary eNB or a gNB.
  • the second base station may be a base station where an RRC entity for the terminal is not located.
  • the second base station may be connected to the first base station.
  • the second SRB may provide exchange of RRC messages between the RRC entity of the first base station and the RRC entity of the terminal.
  • the second SRB may be one or more.
  • the second SRB may be a temporary SRB.
  • the second SRB may be suspended.
  • the first SRB may be in a non-suspended state, while the second SRB may be in a suspended state.
  • the terminal may detect a condition for resuming the suspended second SRB.
  • the terminal may detect a condition of suspending the first SRB.
  • the conditions for resuming the suspended second SRB or the conditions for suspending the first SRB are as follows.
  • the cell quality of the cell at the second base station is better than the threshold value.
  • Condition 1-2 Cell quality of the cell at the first base station is worse than the threshold.
  • Condition 1-3 The timer associated with the radio link failure is started.
  • Condition 1-4 The timer associated with the handover failure is started.
  • Condition 1-5 An RRC connection reestablishment procedure for the terminal is initiated.
  • Condition 1-6 The UE decides to suspend the first SRB. For example, if data cannot be transmitted over the first SRB through the first base station, the terminal may decide to suspend the first SRB.
  • the terminal may resume the suspended second SRB. Furthermore, the terminal may suspend the first SRB.
  • FIG. 8 illustrates a procedure of controlling an SRB by a terminal according to an embodiment of the present invention.
  • the UE may establish an RRC connection with the first base station and set up the first base station and the first SRB.
  • the first base station may be a master eNB or a gNB.
  • the first base station may be a base station where an RRC entity for the terminal is located.
  • the first SRB may provide exchange of RRC messages between the RRC entity of the first base station and the RRC entity of the terminal.
  • the first SRB may be one or more.
  • the terminal may set up a radio resource (and radio bearer) with the second base station, and set up the second base station and the second SRB.
  • the second base station may be a secondary eNB or a gNB.
  • the second base station may be a base station where an RRC entity for the terminal is not located.
  • the second base station may be connected to the first base station.
  • the second SRB may provide exchange of RRC messages between the RRC entity of the first base station and the RRC entity of the terminal.
  • the second SRB may be one or more.
  • the second SRB may be a temporary SRB.
  • the first SRB may be suspended.
  • the second SRB may be in a non-suspended state, while the first SRB may be in a suspended state.
  • the terminal may detect a condition for resuming the suspended first SRB.
  • the terminal may detect a condition of suspending the second SRB.
  • the conditions for resuming the suspended first SRB or the conditions for suspending the second SRB are as follows.
  • the cell quality of the cell at the first base station is better than the threshold value.
  • the cell quality of the cell at the second base station is worse than the threshold value.
  • Condition 2-3 The timer associated with the radio link failure is stopped.
  • Condition 2-4 The timer associated with the handover failure is stopped.
  • the terminal decides to suspend the second SRB. For example, if data cannot be transmitted over the second SRB through the second base station, the terminal may decide to suspend the second SRB.
  • the terminal may resume the suspended first SRB. Furthermore, the terminal may suspend the second SRB.
  • FIG 9 illustrates an example in which a temporary SRB is set according to an embodiment of the present invention.
  • the temporary SRB may be a signaling radio bearer (SRB) set over an MCG and one or more SCGs.
  • the RRC message generated by the RRC in the MCG may be temporarily transmitted through the SCG resource when the connection fails. For example, even when the SRB is in an unavailable state, the terminal may receive an RRC message from the RRC entity of the MCG using the temporary SRB.
  • FIG. 10 illustrates a method for maintaining an RRC connection through a temporary SRB and a procedure for a UE to reestablish an RRC connection when a connection fails according to an embodiment of the present invention.
  • the UE may establish an RRC connection with an old master cell group cell. And, the UE can set up the old MCG cell and SRB1.
  • the SRB1 may be a normal SRB.
  • the UE having set up the old MCG cell and SRB1 in the RRC connection establishment procedure may perform SCG establishment (establishment).
  • SCG secondary cell group cell
  • the temporary SRB may be called t-SRB.
  • the temporary SRB may be in a suspended state until a connection failure occurs.
  • the UE may not use the temporary SRB.
  • step S1030 when the RRC connection between the UE and the old MCG cell is in a bad state, the UE may start using the temporary SRB instead of SRB1.
  • SRB1 may be suspended, and RRC connection may be maintained through the temporary SRB.
  • the UE may begin using a temporary SRB instead of SRB1.
  • the terminal may start using the temporary SRB instead of SRB1.
  • the terminal may start using the temporary SRB instead of SRB1.
  • the terminal may start using the temporary SRB instead of SRB1. For example, if the quality of the old MCG cell is worse than the threshold value, the quality of the SCG cell is better than the threshold value, the terminal may start using the temporary SRB instead of SRB1. For example, if the handover fails, the terminal can start using the temporary SRB instead of SRB1. For example, when an RLF or HOF related timer (eg, T310 or T311) starts, the terminal may start using a temporary SRB instead of SRB1. Although SRB1 is suspended in the RRC connection reestablishment procedure, the temporary SRB can be used to maintain the RRC connection. Data transmission via the DRB may still proceed on the SCG of the SCG bearer or split bearer.
  • RLF or HOF related timer eg, T310 or T311
  • the UE may still perform the RRC connection reestablishment procedure.
  • the RRC connection reestablishment procedure may follow a legacy LTE procedure when the MCG is in the E-UTRAN.
  • steps S1040a to S1040c may be selectively performed.
  • step S1040a if the RRC connection between the UE and the old MCG cell is in a good state, the UE may suspend the temporary SRB and resume SRB1. For example, if the RRC connection reestablishment procedure for the old MCG cell is successfully completed, the UE may suspend the temporary SRB and resume SRB1. For example, if the quality of the old MCG cell is better than the threshold, the terminal may suspend the temporary SRB and resume SRB1. For example, if the quality of the SCG cell is worse than the threshold, the terminal may suspend the temporary SRB and resume SRB1.
  • the terminal may suspend the temporary SRB and resume SRB1. Therefore, after reestablishing the RRC connection in the old MCG cell, the UE may switch from the temporary SRB to SRB1 to maintain the RRC connection.
  • the terminal may establish an RRC connection with a new master cell group cell (MCG cell).
  • MCG cell master cell group cell
  • the UE may set up a new MCG cell and SRB2.
  • the SRB2 may be a normal SRB.
  • the terminal may suspend the temporary SRB and set up SRB2.
  • the terminal may suspend the temporary SRB and set up SRB2.
  • the terminal may suspend the temporary SRB and set up SRB2.
  • the terminal may suspend the temporary SRB and set up SRB2. Therefore, after reestablishing the RRC connection in the new MCG cell, the UE may switch from the temporary SRB to SRB2 to maintain the RRC connection.
  • the terminal may establish an RRC connection with the SCG cell.
  • the UE may set up the SCG cell and the SRB3.
  • the SRB3 may be a normal SRB. That is, the terminal may re-establish the RRC connection with the SCG cell.
  • the SCG cell may be changed to the MCG cell.
  • the terminal may suspend the temporary SRB and set up SRB3.
  • the UE that has set up the SCG cell and the SRB3 in the RRC connection establishment procedure may perform SCG establishment with another SCG cell and may set up the temporary SCB with another SCG cell during the SCG establishment.
  • step S1040d the RRC connection reestablishment procedure may not be completed successfully. If the RRC connection reestablishment procedure is not completed successfully, the terminal may perform at least one of the following options.
  • the terminal enters the RRC_IDLE state. In this case, all radio bearers including the temporary SRB can be released.
  • the terminal enters a new RRC state.
  • the new RRC state may be a new RRC state that is neither an RRC_IDLE state nor an RRC_CONNECTED state.
  • the UE may select a cell in the new RRC state.
  • the new RRC state may be a state in which the UE may perform a cell reselection procedure and maintain the ECM_CONNECTED state.
  • the new RRC state may be an RRC_INACTIVE state.
  • the terminal may perform handover to the cell according to the following steps.
  • the UE may optionally transmit an RRC message requesting handover to the RRC entity of the MCG through the temporary SRB.
  • the RRC entity of the MCG may transmit a handover command message for the target cell to the terminal through the temporary SRB.
  • the terminal may move to the target cell, and transmit a handover complete message to the cell.
  • the cell may be configured as a PCell in MCG.
  • the terminal may still receive the RRC message using the second SRB, thereby improving reliability of RRC message delivery.
  • FIG. 11 is a block diagram illustrating a method of controlling an SRB by a terminal according to an embodiment of the present invention.
  • the UE may establish a radio resource control (RRC) connection and a first SRB with a first base station.
  • the first base station may be a base station where an RRC entity for the terminal is located.
  • the terminal may configure the second base station and the second SRB.
  • the second SRB may be in a suspended state.
  • the second SRB may be a temporary SRB.
  • the second base station may be a base station in which an RRC entity for the terminal is not located.
  • step S1130 if the quality of the cell at the first base station is lower than the first threshold value, the terminal may resume the suspended second SRB.
  • the terminal may suspend the first SRB.
  • the terminal may resume the suspended second SRB.
  • the terminal may resume the suspended second SRB.
  • the terminal may resume the suspended second SRB.
  • the terminal may resume the suspended second SRB.
  • FIG. 12 is a block diagram illustrating a method of controlling an SRB by a terminal according to an embodiment of the present invention.
  • the UE may establish a radio resource control (RRC) connection and a first SRB with a first base station.
  • the first SRB may be in a suspended state.
  • the first base station may be a base station where an RRC entity for the terminal is located.
  • the terminal may configure the second base station and the second SRB.
  • the second SRB may be a temporary SRB.
  • the second base station may be a base station in which an RRC entity for the terminal is not located.
  • step S1230 if the quality of the cell in the first base station is better than the first threshold value, the terminal may resume the suspended first SRB.
  • the terminal may suspend the second SRB.
  • the terminal may resume the suspended first SRB.
  • the terminal may resume the suspended first SRB.
  • the terminal may resume the suspended first SRB.
  • the terminal may resume the suspended first SRB.
  • FIG. 13 is a block diagram of a wireless communication system in which an embodiment of the present invention is implemented.
  • the base station 1300 includes a processor 1301, a memory 1302, and a transceiver 1303.
  • the memory 1302 is connected to the processor 1301 and stores various information for driving the processor 1301.
  • the transceiver 1303 is connected to the processor 1301 to transmit and / or receive a radio signal.
  • the processor 1301 implements the proposed functions, processes, and / or methods. In the above-described embodiment, the operation of the base station may be implemented by the processor 1301.
  • the terminal 1310 includes a processor 1311, a memory 1312, and a transceiver 1313.
  • the memory 1312 is connected to the processor 1311 and stores various information for driving the processor 1311.
  • the transceiver 1313 is connected to the processor 1311 to transmit and / or receive a radio signal.
  • the processor 1311 implements the proposed functions, processes and / or methods. In the above-described embodiment, the operation of the terminal may be implemented by the processor 1311.
  • 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 transceiver may include baseband circuitry for processing wireless signals.
  • the above 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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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne un procédé destiné à un terminal commandant un support radio de signalisation (SRB) dans un système de communication sans fil et un appareil le prenant en charge. Le procédé comprend les étapes consistant : à établir une connexion de commande de ressources radio (RRC) avec une première station de base et à définir un premier SRB ; à définir une seconde station de base et un second SRB, le second SRB étant temporairement suspendu ; et à reprendre le second SRB temporairement suspendu lorsque la qualité d'une cellule dans la première station de base est inférieure à une première valeur critique.
PCT/KR2017/010535 2016-09-28 2017-09-25 Procédé et appareil permettant de commander un srb Ceased WO2018062786A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US16/333,418 US11076442B2 (en) 2016-09-28 2017-09-25 Method and apparatus for controlling SRB

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201662401144P 2016-09-28 2016-09-28
US62/401,144 2016-09-28
KR20170105220 2017-08-21
KR10-2017-0105220 2017-08-21

Publications (1)

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WO2018062786A1 true WO2018062786A1 (fr) 2018-04-05

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PCT/KR2017/010535 Ceased WO2018062786A1 (fr) 2016-09-28 2017-09-25 Procédé et appareil permettant de commander un srb

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CN113747532B (zh) * 2019-03-22 2023-06-06 Oppo广东移动通信有限公司 无线通信的方法、终端设备和网络设备
GB2636136A (en) * 2023-11-30 2025-06-11 Nokia Technologies Oy Configuration of multiple signaling radio bearer sets

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WO2016003224A1 (fr) * 2014-07-02 2016-01-07 엘지전자 주식회사 Procédé d'interfonctionnement réalisé par une station de base et station de base utilisant ce dernier
US20160135103A1 (en) * 2013-07-17 2016-05-12 Lg Electronics Inc Method and apparatus for performing handover procedure for dual connectivity in wireless communication system
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WO2016003224A1 (fr) * 2014-07-02 2016-01-07 엘지전자 주식회사 Procédé d'interfonctionnement réalisé par une station de base et station de base utilisant ce dernier
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CN113747532B (zh) * 2019-03-22 2023-06-06 Oppo广东移动通信有限公司 无线通信的方法、终端设备和网络设备
GB2636136A (en) * 2023-11-30 2025-06-11 Nokia Technologies Oy Configuration of multiple signaling radio bearer sets

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