Communication method and device

Abstract

A communication method and apparatus may be applied to a communication scenario in which a network controlled repeater (NCR) is deployed. The method includes: a first access network device determines indication information and transmits system information of a first cell, where the system information includes the indication information. The indication information indicates a public land mobile network PLMN corresponding to a first synchronization signal and a physical broadcast channel block (SSB) of the first cell. A first terminal device receives the system information and determines the PLMN corresponding to the first SSB based on the indication information in the system information. Based on this solution, a specific PLMN is configured for SSBs that can be forwarded by the NCR, allowing terminal devices that select the specific PLMN to access the network via the NCR and denying terminal devices that select other PLMNs from accessing the network via the NCR. As a result, the NCR serves terminal devices that select the specific PLMN, improving operator control over the NCR.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to Chinese Patent Application No. 202211724099.0, entitled "COMMUNICATION METHOD AND APPARATUS," filed with the State Intellectual Property Office of China on December 30, 2023, and Chinese Patent Application No. 202310149707.8, entitled "COMMUNICATION METHOD AND APPARATUS," filed with the State Intellectual Property Office of China on February 14, 2022, both of which applications are incorporated herein by reference in their entireties.

[0002] [Technical field] TECHNICAL FIELD Embodiments of this application relate to the field of communications, and in particular to communication methods and devices. [Background technology]

[0003] The fifth-generation (5G) mobile communication system uses spectrum resources with higher frequency bands to obtain wider transmission bandwidths. However, due to the propagation characteristics of high-frequency radio, the propagation loss and penetration loss of high-frequency radio are very large. As a result, it is difficult to expand the coverage area, and even within the coverage area, dead spots exist. Therefore, the 5G system requires a relay system to expand the coverage area.

[0004] As an intelligent repeater, the network controlled repeater (NCR) supports functions such as uplink and downlink sensing, dynamic time division duplex (TDD), beam sensing, access side beamforming (BF), uplink and downlink transmit power control, and dynamic switching, enabling easy and efficient area expansion.

[0005] Currently, the related implementation of an integrated access and backhaul (IAB) node is usually used in the design of an NCR. However, the NCR and IAB nodes are not completely the same. Therefore, the related implementation of an IAB node cannot be completely copied for an NCR. Summary of the Invention

[0006] This application provides a communication method and apparatus for designing related implementations of NCR.

[0007] According to a first aspect, there is provided a communication method, which may be executed by a first terminal device, or may be executed by a component of the first terminal device, such as a processor, chip, or chip system of the first terminal device, or may be realized by a logic module or software capable of realizing all or part of the functions of the first terminal device, the method including the steps of receiving system information of a first cell, the system information including indication information, the indication information indicating a public land mobile network (PLMN) corresponding to a first synchronization signal and a physical broadcast channel block (SSB) of the first cell, and determining a PLMN corresponding to the first SSB based on the indication information.

[0008] Based on this solution, the first terminal device may know the correspondence relationship between the SSB and the PLMN based on the received system information, and perform related processing based on the correspondence relationship. For example, the terminal device may select an SSB based on the correspondence relationship between the SSB and the PLMN and the PLMN selected by the terminal device, thereby increasing the access success rate of the terminal device.

[0009] In a possible design, if the PLMN corresponding to the first SSB includes the first PLMN, the first SSB supports a terminal device that selects the first PLMN when performing initial access.

[0010] Based on a possible design, if the SSB selected by the first terminal device is the first SSB and the PLMN selected by the first terminal device is the first PLMN, the first SSB supports the terminal device in selecting the first PLMN when performing initial access, so the first terminal device may perform initial access based on the first SSB.

[0011] In a possible design, if the PLMN corresponding to the first SSB does not include the first PLMN, the first SSB does not support a terminal device that selects the first PLMN when performing initial access.

[0012] Based on a possible design, if the SSB selected by the first terminal device is the first SSB and the PLMN selected by the first terminal device is the first PLMN, the first SSB does not support the terminal device selecting the first PLMN when performing initial access, so the first terminal device may reselect another SSB.

[0013] In a possible design, the first SSB is an SSB selected by the first terminal device in the initial access procedure, and the communication method further includes selecting a fifth SSB of the first cell and performing initial access based on the fifth SSB when the PLMN corresponding to the first SSB does not include the first PLMN, or performing initial access based on the first SSB when the PLMN corresponding to the first SSB includes the first PLMN, where the first PLMN is the PLMN selected by the first terminal device in the initial access procedure.

[0014] In a possible design, the indication information further indicates a PLMN corresponding to the fifth SSB, where the PLMN corresponding to the fifth SSB includes the first PLMN.

[0015] Based on a possible design, the terminal device may determine whether to continue completing initial access based on the SSB selected by the terminal device or reselect an SSB based on the correspondence between the SSB and the PLMN and the SSB and PLMN selected by the terminal device. For example, if the PLMN corresponding to the SSB selected by the terminal device includes the PLMN selected by the terminal device, the terminal device continues completing initial access based on the SSB selected by the terminal device, or if the PLMN corresponding to the SSB selected by the terminal device does not include the PLMN selected by the terminal device, the terminal device reselects an SSB. Based on this, a specific PLMN is configured for SSBs that can be forwarded by NCR, allowing terminal devices that select the specific PLMN to access the network via the NCR and denying terminal devices that select other PLMNs from accessing the network via the NCR. As a result, the NCR serves terminal devices that select the specific PLMN, improving the operator's control over NCR.

[0016] In a possible design, the indication information includes an identifier of the first SSB and identification information of the PLMN corresponding to the first SSB.

[0017] According to a second aspect, there is provided a communication method. The method may be executed by a first access network device, or may be executed by a component of the first access network device, such as a processor, chip, or chip system of the first access network device, or may be realized by a logic module or software capable of realizing all or part of the functions of the first access network device. The method includes the steps of determining indication information and transmitting system information of a first cell, the system information including the indication information. The indication information indicates a public land mobile network (PLMN) corresponding to a first synchronization signal and a physical broadcast channel block (SSB) of the first cell.

[0018] Based on this solution, the access network device may broadcast the PLMN corresponding to the SSB in the system information, so that the terminal device receiving the system information can know the correspondence between the SSB and the PLMN and perform related processing based on the correspondence. For example, the terminal device may decide to continue completing the initial access based on the SSB selected by the terminal device or to reselect the SSB based on the correspondence between the SSB and the PLMN and the SSB and PLMN selected by the terminal device. For example, if the PLMN corresponding to the SSB selected by the terminal device includes the PLMN selected by the terminal device, the terminal device continues to complete the initial access based on the SSB selected by the terminal device, or if the PLMN corresponding to the SSB selected by the terminal device does not include the PLMN selected by the terminal device, the terminal device reselects the SSB.

[0019] Based on this, a specific PLMN is configured for SSBs that can be forwarded by the NCR, allowing terminal devices that select the specific PLMN to access the network via the NCR and denying terminal devices that select other PLMNs from accessing the network via the NCR, thereby allowing the NCR to serve terminal devices that select the specific PLMN and improving the operator's control over the NCR.

[0020] In a possible design, if the PLMN corresponding to the first SSB includes the first PLMN, the first SSB supports a terminal device that selects the first PLMN when performing initial access.

[0021] In a possible design, if the PLMN corresponding to the first SSB does not include the first PLMN, the first SSB does not support a terminal device that selects the first PLMN when performing initial access.

[0022] In a possible design, the indication information includes an identifier of the first SSB and identification information of the PLMN corresponding to the first SSB.

[0023] According to a third aspect, there is provided a communication method, which may be executed by a first access network device, or may be executed by a component of the first access network device, such as a processor, chip, or chip system of the first access network device, or may be realized by a logic module or software capable of realizing all or part of the functions of the first access network device, the method including: receiving first information via a first NCR, the first information indicating a first public land mobile network PLMN, the first PLMN being a PLMN selected by the first terminal device in an initial access procedure; and denying access of the first terminal device via the first NCR if the first NCR does not support the first PLMN.

[0024] Based on this solution, for a terminal device accessing a network via an NCR, the access network device may determine whether the NCR supports the PLMN selected by the terminal device. If the NCR does not support the PLMN selected by the terminal device, the access of the terminal device via the NCR is denied. In other words, through the control of the access network device, a terminal device that selects a PLMN supported by the NCR may be allowed to access the network via the NCR and enjoy the relay service provided by the NCR, while a terminal device that selects a PLMN not supported by the NCR may be denied to access the network via the NCR. Thus, the NCR provides services to terminal devices that select a specific PLMN, improving the operator's control over the NCR.

[0025] In one possible design, the method further includes receiving second information, the second information indicating at least one PLMN supported by the first NCR.

[0026] In a possible design, if the PLMN selected by the first NCR in the initial access procedure is different from the first PLMN, the first NCR does not support the first PLMN.

[0027] In a possible design, if the first PLMN does not support access of the network controlled repeater mobile terminal NCR-MT, the first NCR does not support the first PLMN.

[0028] In a possible design, before receiving the first information via the first NCR, the method further includes a step of transmitting system information, the system information indicating whether the first cell supports NCR-MT access.

[0029] Based on a possible design, whether the first cell supports NCR-MT access is configured at the granularity of the cell, so that the signaling overhead can be reduced.

[0030] In a possible design, before receiving the first information via the first NCR, the method further includes a step of transmitting system information, the system information indicating whether each PLMN supported by the first cell supports NCR-MT access.

[0031] Based on a possible design, whether each PLMN supports NCR-MT access can be configured at the granularity of the PLMN, thereby improving the flexibility of the configuration.

[0032] In a possible design, the step of denying access to the first terminal device via the first NCR includes performing beam switching for the first terminal device.

[0033] In a possible design, the step of denying access of the first terminal device via the first NCR includes a step of sending a radio resource control (RRC) message to the first terminal device, the RRC message being used to release an RRC connection between the first terminal device and the first access network device.

[0034] In a possible design, the RRC message includes third information, which indicates a second SSB, which is used for the next access of the first terminal device, and the SSBs that can be forwarded by the first NCR do not include the second SSB, or the third information indicates a third SSB, which is not used for the next access of the first terminal device, and the third SSB is an SSB that can be forwarded by the first NCR.

[0035] According to a possible design, the first access network device indicates to the first terminal device an SSB to be selected during the next access, thereby avoiding the first terminal device still selecting an SSB that does not support the first PLMN to perform the next access, thereby reducing the access delay of the first terminal device and improving access efficiency. Alternatively, the first access network device indicates to the first terminal device an SSB that cannot be used for the first terminal device's access, thereby avoiding the first terminal device selecting an SSB that cannot be used for the first terminal device's access during the next access, thereby reducing the access delay of the first terminal device and improving access efficiency.

[0036] In one possible design, denying access to the first terminal device via the first NCR includes performing a cell handover for the first terminal device.

[0037] Based on a possible design, the signal quality of the first terminal device can be improved. This is because the first terminal device accesses the first access network device through the first NCR, which indicates that the first terminal device may be located at the cell edge of the first cell. If the first terminal device cannot access the first cell through the first NCR, the signal quality after the first terminal device does not access the first cell through the first NCR is very poor. Therefore, a cell handover is performed for the first terminal device, so that the first terminal device can access a target cell with good signal quality, thereby improving the signal quality of the first terminal device.

[0038] In a possible design, the step of performing a cell handover to the first terminal device includes a step of sending measurement configuration information to the first terminal device, wherein the SSB that can be forwarded by the second NCR is not present in the measurement object indicated by the measurement configuration information, and the PLMNs served by the second NCR do not include the first PLMN.

[0039] Based on the configuration of the measurement object, the first terminal device does not measure the SSB that can be transferred by the second NCR, and therefore does not select the SSB, i.e., does not access the network via the second NCR, thereby avoiding the case where the first terminal device is rejected by the access network device after accessing the network via the second NCR, thereby improving cell handover efficiency.

[0040] In a possible design, the second NCR includes an NCR controlled by a second access network device.

[0041] In a possible design, the method further includes receiving fourth information, the fourth information indicating SSBs that can be forwarded by at least one NCR controlled by the second access network device and / or PLMNs served by the at least one NCR.

[0042] According to a fourth aspect, there is provided a communication method. The method may be executed by a first NCR, or may be executed by a component of the first NCR, such as a processor, chip, or chip system of the first NCR, or may be realized by a logic module or software capable of realizing all or part of the functions of the first NCR. The method includes the steps of determining second information and sending the second information to a first access network device. The second information indicates at least one public land mobile network (PLMN) supported by the first NCR, and the first NCR is an NCR controlled by the first access network device.

[0043] Based on this solution, the first NCR indicates at least one PLMN supported by the first NCR to the first access network device, so that the first access network device knows the at least one PLMN supported by the first NCR, determines whether the first NCR supports the PLMN selected by the terminal device accessing the network via the first NCR, and can further perform access control for the terminal device.

[0044] According to a fifth aspect, there is provided a communication method. The method may be executed by a first NCR, or may be executed by a component of the first NCR, such as a processor, chip, or chip system of the first NCR, or may be realized by a logic module or software capable of realizing all or part of the functions of the first NCR. The method includes: a first network controlled repeater mobile terminal (NCR-MT) determines that a frequency band supported by a first network controlled repeater forwarding module (NCR-Fwd) is a first frequency band, and the first NCR-MT performs initial access on the first frequency band.

[0045] Based on this solution, when performing initial access, the NCR-MT takes into account the capabilities of the NCR-Fwd and performs initial access or measurement on the frequency band supported by the NCR-Fwd, so that after the NCR-MT subsequently accesses the network, the NCR-Fwd can also operate normally, avoiding the case where the cell accessed by the NCR-MT is on a frequency band not supported by the NCR-Fwd, and ensuring the normal operation of the NCR.

[0046] In a possible design, after the first NCR-MT completes initial access, the method further includes: the first NCR-MT measures a synchronization signal and a physical broadcast channel block SSB on the first frequency band.

[0047] According to a sixth aspect, there is provided a communication method. The method may be executed by a first NCR, or may be executed by a component of the first NCR, such as a processor, chip, or chip system of the first NCR, or may be realized by a logic module or software capable of realizing all or part of the functions of the first NCR. The method includes:

[0048] The first network controlled repeater mobile terminal NCR-MT receives system information of the first cell, the system information including NCR support information, closed access group (CAG) information corresponding to at least one public land mobile network (PLMN) supported by the first cell, and cell reservation information, the NCR support information indicating whether each PLMN supported by the first cell supports access for the NCR-MT, the cell reservation information indicating whether the first cell is a reserved cell, the first NCR-MT ignores the CAG information and the cell reservation information and accesses the first cell when the NCR support information indicates that the first PLMN supports access for the NCR-MT, and the first PLMN is the PLMN selected by the first NCR-MT in the initial access procedure.

[0049] Based on this solution, the NCR-MT ignores CAG information and cell reservation information, so that non-NPN NCRs (i.e., NCRs that do not satisfy the NPN constraints) are allowed to access CAG-only cells, improving the coverage of non-NPN NCRs, reducing the production cost and complexity of NCRs, and facilitating large-scale deployment of NCRs.

[0050] Furthermore, because NCR-Fwd transparently amplifies and forwards only physical signals, ignoring NPN constraints by NCR-MT does not affect general terminal devices. Even when a non-NPN NCR accesses a CAG-only cell, the general terminal device in the CAG-only cell still determines the NPN constraints, and the AMF network element still performs NPN access control for the general terminal device. This prevents non-NPN UEs from accessing the CAG-only cell and does not cause extra energy consumption for the general terminal device.

[0051] According to a seventh aspect, there is provided a communication method. The method may be executed by a mobility management network element, or may be executed by a component of the mobility management network element, such as a processor, chip, or chip system of the mobility management network element, or may be realized by a logical module or software that can realize all or part of the functions of the mobility management network element. The method includes: the mobility management network element receives a fourth message from a first access network device, the fourth message including fifth information, where the fifth information indicates that a terminal device associated with the fourth message is a network controlled repeater mobile terminal NCR-MT, and the mobility management network element determines not to perform non-public network NPN access control for the terminal device based on the fifth information.

[0052] Based on this solution, the mobility management network element does not perform NPN access control for the NCR-MT, so that non-NPN NCRs (i.e., NCRs that do not satisfy the NPN constraints) are allowed to access CAG-only cells, improving the coverage of non-NPN NCRs, reducing the production cost and complexity of NCRs, and facilitating large-scale deployment of NCRs.

[0053] According to an eighth aspect, there is provided a communication method. The method may be executed by a first access network device, or may be executed by a component of the first access network device, such as a processor, chip, or chip system of the first access network device, or may be realized by a logic module or software capable of realizing all or part of the functions of the first access network device. The method includes:

[0054] The first access network device sends a first message to the mobility management network element, where the first message is used to request a system temporary mobile subscriber identity (S-TMSI) of the first network controlled repeater mobile terminal (NCR-MT), or the first message is used to request the mobility management network element to retain an NG interface application protocol identity (NGAP ID) of the first NCR-MT. When the first access network device needs to send control information to the idle first NCR-MT, the first access network device sends a second message to the mobility management network element, where the second message is used to request initiating paging for the idle first NCR-MT, and the second message includes the S-TMSI of the first NCR-MT, or the second message includes the NGAP ID of the first NCR-MT.

[0055] Based on this solution, when the access network device releases the NCR-MT to the RRC idle state, the access network device requests the S-TMSI of the NCR-MT from the mobility management network element or requests the mobility management network element to store the NGAP ID of the NCR-MT, so that when the access network device needs to send control information to the NCR-MT again, the access network device may identify the NCR-MT by using the S-TMSI or NGAP ID, so that the mobility management network element can send a paging message to the NCR-MT and wake up the NCR-MT, allowing the NCR-MT to enter the RRC connected state.

[0056] In other words, based on this solution, after releasing the NCR-MT to the RRC idle state, the access network device can wake up the NCR-MT again. NCR energy saving is realized without affecting the access network device's control over the NCR. This facilitates the normal operation of the NCR.

[0057] In a possible design, the first message includes the radio access network side NGAP ID of the first NCR-MT and / or the mobility management network element side NGAP ID of the first NCR-MT.

[0058] In a possible design, the first message is used to request an S-TMSI of the first NCR-MT, and the method further includes: the first access device receives a third message from the mobility management network element, the third message including the S-TMSI of the first NCR-MT, and the first access network device stores the S-TMSI of the first NCR-MT.

[0059] In a possible design, the second message includes the S-TMSI of the first NCR-MT.

[0060] In a possible design, the first message is used to request the mobility management network element to retain the NGAP identification information of the first NCR-MT, and the method includes: the first access network device stores the NGAP ID of the first NCR-MT.

[0061] In a possible design, the second message includes the NGAP ID of the first NCR-MT.

[0062] According to a ninth aspect, there is provided a communication method. The method may be executed by a first access network device, or may be executed by a component of the first access network device, such as a processor, chip, or chip system of the first access network device, or may be realized by a logic module or software capable of realizing all or part of the functions of the first access network device. The method includes: the first access network device sends measurement configuration information to a first terminal device, and an SSB that can be forwarded by a second NCR does not exist in a measurement object indicated by the measurement configuration information, the PLMNs served by the second NCR do not include the first PLMN, and the first PLMN is a PLMN selected by the first terminal device in an initial access procedure.

[0063] Based on this solution, since the SSB that can be transferred by the second NCR does not exist in the measurement object configured by the first access network device for the first terminal device, the first terminal device does not measure the SSB that can be transferred by the second NCR, and therefore does not select the SSB, i.e., does not access the network via the second NCR, thereby avoiding the case where the first terminal device accesses the network via the wrong NCR, and improving the network access efficiency of the terminal device.

[0064] In a possible design, the second NCR includes an NCR controlled by a second access network device.

[0065] According to a tenth aspect, there is provided a communication method. The method may be executed by a first access network device, or may be executed by a component of the first access network device, such as a processor, chip, or chip system of the first access network device, or may be realized by a logic module or software capable of realizing all or part of the functions of the first access network device. The method includes: the first access network device receives fourth information from a second access network device, the fourth information indicating SSBs that can be forwarded by at least one NCR controlled by the second access network device and / or PLMNs served by the at least one NCR.

[0066] Based on this solution, the first access network device can know relevant information of the NCR controlled by the second access network device, so that the first access network device configures a cell of the first access network device or a terminal device accessing the first access network device. For example, the first access network device may configure an appropriate measurement object for the terminal device accessing the first access network device based on relevant information of the NCR controlled by the second access network device.

[0067] In a possible design, the method further includes: the first access network device sending sixth information to the second access network device, the sixth information indicating SSBs that can be forwarded by at least one NCR controlled by the first access network device and / or PLMNs served by the at least one NCR.

[0068] According to an eleventh aspect, there is provided a communication method. The method may be executed by a first NCR, or may be executed by a component of the first NCR, such as a processor, chip, or chip system of the first NCR, or may be realized by a logic module or software capable of realizing all or part of the functions of the first NCR. The method includes: when a first condition is met, the first NCR-Fwd determines that the first NCR-MT needs to enter an idle state, and the first NCR-MT sends a first message to a first access network device, where the first message is used to request the first NCR-MT to release a radio resource control connection (RRC connection).

[0069] The first condition includes: the first NCR-Fwd receives first instruction information from the first operation, administration and maintenance server, the first instruction information indicating to turn off the first NCR or instructing the first NCR-MT to enter an idle state; alternatively, the first condition includes that the turn-off time of the first NCR arrives.

[0070] Based on this solution, the NCR-Fwd may determine whether the NCR-MT needs to enter the idle state. When the NCR-MT needs to enter the idle state, the NCR-MT requests the access network device to release the NCR-MT's RRC connection and enters the idle state. This conforms to the currently defined principle that only the access network device can control the NCR-MT to enter the idle state, and is highly compatible. Furthermore, when receiving instruction information indicating that the NCR should be turned off or when the NCR's off time arrives, the NCR-Fwd determines that the NCR-MT needs to enter the idle state. Since the NCR-MT may not need to control the NCR-Fwd after the NCR-Fwd is turned off, the NCR-MT enters the idle state in this scenario, thereby realizing NCR energy savings.

[0071] According to a twelfth aspect, there is provided a communication method, which may be executed by a first access network device, or may be executed by a component of the first access network device, such as a processor, chip, or chip system of the first access network device, or may be realized by a logical module or software capable of realizing all or part of the functions of the first access network device, the method including: receiving a second message from a second Operation, Administration, and Maintenance (OAM) Server, where the second message is used to notify the first access network device to release a radio resource control (RRC) connection of the first NCR-MT; and sending a third message to the first NCR, where the third message is used to release the RRC connection of the first NCR-MT.

[0072] Based on this solution, the access network device may release the NCR-MT to the idle state based on the notification or request of the OAM server. This conforms to the currently defined principle that only the access network device can control the NCR-MT to enter the idle state, and has high compatibility. Furthermore, when it determines that the NCR-Fwd is off, the OAM server may notify or request that the NCR-MT be released to the idle state. Since the NCR-MT may not need to control the NCR-Fwd after the NCR-Fwd is turned off, the NCR-MT is released to the idle state in this scenario, realizing NCR energy savings.

[0073] In one possible design, the second message includes an identifier of the first NCR.

[0074] According to a thirteenth aspect, there is provided a communication method, which may be executed by a first access network device, or may be executed by a component of the first access network device, such as a processor, chip, or chip system of the first access network device, or may be realized by a logic module or software capable of realizing all or part of the functions of the first access network device, the method including: receiving a fourth message from a second Operation, Administration, and Maintenance OAM Server, where the fourth message is used to notify the first access network device to instruct the first NCR-MT to enter a connected state; and sending a broadcast message, where the broadcast message instructs the first NCR-MT to enter a connected state.

[0075] Based on this solution, after the NCR-MT enters the idle state, the access network device may send a broadcast message to instruct the NCR-MT to enter the connected state based on the notification message of the OAM server. In other words, after the NCR-MT is released to the RRC idle state, the NCR-MT can wake up again. NCR energy savings are achieved without affecting the access network device's control over the NCR. This facilitates normal operation of the NCR.

[0076] In one possible design, the broadcast message includes an identifier of the first NCR and second instruction information, and the second instruction information instructs the first NCR-MT to enter a connected state. In one possible design, the broadcast message is a SIB or a MIB.

[0077] According to a fourteenth aspect, there is provided a communication apparatus for implementing various methods. The communication apparatus may be the first terminal device of the first aspect or an apparatus, such as a chip or chip system, included in the first terminal device. The communication apparatus may be the first access network device of the second, third, eighth, ninth, tenth, twelfth, or thirteenth aspects or an apparatus, such as a chip or chip system, included in the first access network device. The communication apparatus may be the first NCR of the fourth, fifth, sixth, or eleventh aspects or an apparatus, such as a chip or chip system, included in the first NCR. Alternatively, the communication apparatus may be the mobility management network element of the seventh aspect or an apparatus, such as a chip or chip system, included in the mobility management network element. The communication apparatus includes corresponding modules, units, or means for implementing the methods. The modules, units, or means may be implemented by hardware, software, or hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to functions.

[0078] In some possible designs, the communications device may include a processing module and a transceiver module. The processing module may be configured to implement the processing functions of any one of the above aspects and any one of the possible implementations of the above aspects. The transceiver module may include a receiving module and a transmitting module configured to implement the receiving function and the transmitting function, respectively, of any one of the above aspects and any one of the possible implementations of the above aspects.

[0079] In some possible designs, a transceiver module may include a transceiver circuit, a transceiver machine, a transceiver, or a communication interface.

[0080] According to a fifteenth aspect, there is provided a communication apparatus including a processor and a memory. The memory is configured to store computer instructions. When the processor executes the instructions, the communication apparatus is capable of performing a method according to any one of the above aspects. The communication apparatus may be the first terminal device of the first aspect or an apparatus, such as a chip or chip system, included in the first terminal device. The communication apparatus may be the first access network device of the second, third, eighth, ninth, tenth, twelfth, or thirteenth aspects or an apparatus, such as a chip or chip system, included in the first access network device. The communication apparatus may be the first NCR of the fourth, fifth, sixth, or eleventh aspects or an apparatus, such as a chip or chip system, included in the first NCR. Alternatively, the communication apparatus may be the mobility management network element of the seventh aspect or an apparatus, such as a chip or chip system, included in the mobility management network element.

[0081] According to a sixteenth aspect, there is provided a communication apparatus including a processor and a communication interface. The communication interface is configured to receive and / or transmit signals, and the processor is configured to execute a computer program or instructions to enable the communication apparatus to perform a method according to any one of the above aspects. The communication apparatus may be the first terminal device of the first aspect or an apparatus, such as a chip or chip system, included in the first terminal device. The communication apparatus may be the first access network device of the second, third, eighth, ninth, tenth, twelfth, or thirteenth aspects or an apparatus, such as a chip or chip system, included in the first access network device. The communication apparatus may be the first NCR of the fourth, fifth, sixth, or eleventh aspects or an apparatus, such as a chip or chip system, included in the first NCR. Alternatively, the communication apparatus may be the mobility management network element of the seventh aspect or an apparatus, such as a chip or chip system, included in the mobility management network element.

[0082] According to a seventeenth aspect, there is provided a communication apparatus including at least one processor. The processor is configured to execute computer programs or instructions stored in a memory to enable the communication apparatus to perform a method according to any one of the above aspects. The memory may be coupled to the processor or may be independent of the processor. The communication apparatus may be the first terminal device of the first aspect or an apparatus, such as a chip or chip system, included in the first terminal device. The communication apparatus may be the first access network device of the second, third, eighth, ninth, tenth, twelfth, or thirteenth aspects or an apparatus, such as a chip or chip system, included in the first access network device. The communication apparatus may be the first NCR of the fourth, fifth, sixth, or eleventh aspects or an apparatus, such as a chip or chip system, included in the first NCR. Alternatively, the communication apparatus may be the mobility management network element of the seventh aspect or an apparatus, such as a chip or chip system, included in the mobility management network element.

[0083] According to an eighteenth aspect, there is provided a computer-readable storage medium storing a computer program or instructions that, when executed on a communication device, enables the communication device to perform a method according to any one of the above aspects.

[0084] According to a nineteenth aspect, there is provided a computer program product comprising instructions, which, when executed on a communications device, enable the communications device to perform a method according to any one of the above aspects.

[0085] According to a twentieth aspect, there is provided a communications device (e.g., the communications device may be a chip or a chip system), the communications device including a processor configured to implement the functionality of any one of the above aspects.

[0086] In some possible designs, the communication device includes a memory configured to store necessary program instructions and data.

[0087] In some possible designs, when the device is a chip system, the device may include the chip, or may include both the chip and other discrete components.

[0088] It can be understood that when the communication device provided in any one of the fourteenth to twentieth aspects is a chip or a chip system, the transmitting operation / function of the communication device can be understood as outputting information, and the receiving operation / function of the communication device can be understood as inputting information.

[0089] The technical effects provided by any one of the designs of the 14th to 20th aspects refer to the technical effects provided by the different designs of the 1st to 13th aspects, and the details will not be described again in this specification. [Brief explanation of the drawings]

[0090] [Figure 1] 1 is a diagram of a communication scenario in which NCR is deployed in accordance with this application. [Figure 2] 1 is a diagram of the structure of the NCR according to this application. [Figure 3] 1 is a schematic flow chart of initial access of an IAB node or NCR according to the present application. [Figure 4] 1 is a schematic flowchart of access control in an NPN according to this application. [Figure 5] 1 is a diagram of the structure of a communication system according to this application; [Figure 6] 1 is a schematic flow chart of a communication method according to the present application. [Figure 7] 1 is a schematic flow chart of a communication method according to the present application. [Figure 8] 1 is a schematic flow chart of a communication method according to the present application. [Figure 9]1 is a schematic flow chart of a cell handover according to the present application. [Figure 10] 1 is a schematic flow chart of a communication method according to the present application. [Figure 11] 1 is a schematic flow chart of a communication method according to the present application. [Figure 12] 1 is a schematic flow chart of the initial access according to this application. [Figure 13] 1 is a schematic flow chart of a communication method according to the present application. [Figure 14] 1 is a schematic flow chart of a communication method according to the present application. [Figure 15] 1 is a schematic flow chart of a communication method according to the present application. [Figure 16] 1 is a diagram of the structure of a communication device according to this application; [Figure 17] 1 is a diagram of the structure of another communication device according to the present application; [Figure 18] 1 is a schematic flow chart of a communication method according to the present application. [Figure 19] FIG. 1 is a diagram of the data plane protocol stack of an OAM Server and an NCR according to this application. [Figure 20] 1 is a schematic flow chart of a communication method according to the present application. [Figure 21] 1 is a schematic flow chart of a communication method according to the present application. DETAILED DESCRIPTION OF THE INVENTION

[0091] In the description of this application, unless otherwise specified, " / " represents an "or" relationship between related objects. For example, A / B may represent A or B. In this application, "and / or" simply describes an association relationship between related objects and indicates that three relationships may exist. For example, A and / or B may represent three cases, namely, that only A exists, that both A and B exist, and that only B exists, and A and B may be singular or plural.

[0092] Furthermore, in the description of this application, "plurality" means two or more unless otherwise specified. "At least one of the following items" or similar expressions means any combination of those items, including any combination of a single item or multiple items. For example, at least one of a, b, or c may refer to a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c may be singular or plural.

[0093] Furthermore, in order to clearly describe the technical solutions in the embodiments of this application, terms such as "first" and "second" are used to distinguish between the same or similar items that provide essentially the same function or purpose in the embodiments of this application. Those skilled in the art can understand that terms such as "first" and "second" do not limit the number or execution order, and terms such as "first" and "second" do not indicate clear distinctions.

[0094] Furthermore, in the embodiments of this application, words such as "exemplary," "for example," and the like represent providing an example, illustration, or explanation. Any embodiment or design manner described as "for example" or "for example" in the embodiments of this application should not be described as being preferred or having more advantages than other embodiments or design manners. Rather, the use of terms such as "for example" or "for example" is intended to present related concepts in a particular way for ease of understanding.

[0095] The term "embodiment" as used throughout this specification may be understood to mean that a particular feature, structure, or characteristic associated with this embodiment is included in at least one embodiment of this application. Thus, embodiments throughout the specification do not necessarily refer to the same embodiment. Furthermore, these particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. It may be understood that the sequence numbers of various processes do not imply an execution order in the various embodiments of this application. The execution order of the processes should be determined based on the functions and internal logic of the processes and should not be construed as any limitation on the implementation process of the embodiments of this application.

[0096] In this application, "when" and "if" may be understood to mean that the corresponding processing is performed in a target situation, is not intended to be time-limited, does not require a decision action during implementation, and does not imply any other limitation.

[0097] It can be understood that in some scenarios, some optional features in the embodiments of this application may be independently implemented to solve corresponding technical problems and achieve corresponding effects, without relying on other features, for example, on the solutions on which the optional features are currently based. Alternatively, in some scenarios, optional features may be combined with other features based on requirements. Correspondingly, the devices provided in the embodiments of this application may also implement these features or functions accordingly. Details will not be described herein.

[0098] In this application, unless otherwise specified, the same or similar parts in the embodiments will refer to each other. In the embodiments and implementation methods / methods in the embodiments of this application, unless otherwise specified or unless a logical contradiction occurs, the terms and / or descriptions will be consistent and may be cross-referenced between different embodiments and implementation methods / methods in the embodiments. The technical features in different embodiments and implementation methods / methods in the embodiments may be combined to form new embodiments, implementation methods or methods based on their internal logical relationships. The following implementation methods in this application are not intended to limit the protection scope of this application.

[0099] To facilitate understanding of the technical solutions in the embodiments of this application, the related art of this application is first briefly described below.

[0100] 1. Radio frequency (RF) repeater:

[0101] Coverage is a fundamental function of cellular networks. Deploying relay nodes in areas with poor signal coverage can extend the network coverage area. As a non-regenerative relay node, a radio frequency repeater may amplify and forward received signals and has advantages such as low cost, simple structure, easy deployment, low power consumption, and low maintenance cost. Based on these advantages, deploying radio frequency repeaters has become the simplest and most cost-effective solution for improving network coverage. Therefore, radio frequency repeaters have been widely deployed in second-generation (2G), third-generation (3G), and fourth-generation (4G) mobile communication systems.

[0102] It should be noted that "repeater" in this application may also be referred to as "repeater" and the two descriptions may be interchangeable.

[0103] 2. New Radio (NR) Repeater:

[0104] Fifth-generation (5G) mobile communication systems use spectrum resources with higher frequency bands to obtain wider transmission bandwidths. However, due to the propagation characteristics of high-frequency radio, the propagation loss and penetration loss of high-frequency radio are very large. As a result, it is difficult to expand the coverage area, and even within the coverage area, dead spots exist. Therefore, more relay systems are needed to expand the coverage area. An NR repeater (also called a 5G RF repeater) is a repeater introduced in 5G systems. An NR repeater usually includes only a radio unit (RU).

[0105] The NR repeater may support frequency division duplex (FDD) or time division duplex (TDD) in the 5G frequency range 1 (FR1) and frequency range 2 (FR2) frequency bands.

[0106] Furthermore, 5G systems will support technologies such as dynamic TDD, bandwidth part (BWP), massive multi-input multi-output, and hybrid beamforming (BF), so NR repeaters will have significantly different capabilities than before.

[0107] Based on the current 3GPP standard, NR repeaters do not perform adaptive beamforming on the user access side, but typically use static beamforming with a fixed direction. This solution results in poor performance when the access side terminal device encounters strong interference.

[0108] 3. Network Controlled Repeater (NCR):

[0109] The NCR is also called an intelligent repeater. The NCR may acquire effective control information such as timing information, spatial beam information, bandwidth information, and switching information, and realize functions such as uplink and downlink sensing, dynamic TDD, configurable bandwidth, beam sensing, access side BF, uplink / downlink (DL / UL) transmission power control, and dynamic switching.

[0110] For example, as shown in Figure 1, NCR may realize adaptive baseband filtering at the user access side, which can provide better relaying for communication between terminal devices and base stations. In the FR2 frequency band, NCR with adaptive baseband filtering capability can realize easy and efficient area deployment.

[0111] The NCR differs from a typical repeater in terms of architecture. As shown in Figure 2, the NCR includes an RU module and a mobile terminal (MT) module. The RU module of the NCR is also called a forwarding module, commonly referred to as NCR-Fwd. The NCR-Fwd has the function of transparently amplifying and forwarding physical layer signals without protocol stack processing. The MT module of the NCR, commonly referred to as NCR-MT, is configured to receive and feed back base station control signaling.

[0112] The link between the NCR-Fwd and the terminal device is called the access link, and the link between the NCR-Fwd and the base station is called the backhaul link. The link between the NCR-MT and the base station is called the control link. The control link is the same as the radio resource control (RRC) connection between a general terminal device and a base station. In other words, the NCR-MT has the protocol functions of the RRC layer and each layer below the RRC layer. That is, the NCR-MT has the protocol functions of the RRC layer, radio link control (RLC) layer, medium access control (MAC) layer, and physical (PHY) layer.

[0113] The base station may send control information (e.g., beam direction and power control) of the NCR-Fwd to the NCR-MT. For example, the base station may send the control information to the NCR-MT by using an RRC message, a MAC control element (CE), etc. After receiving the control information, the NCR-MT controls the NCR-Fwd to perform corresponding operations. In other words, the "network control" function in the NCR is mainly reflected in the interaction between the base station and the NCR-MT. The NCR-Fwd is the controlled object and has simple functions.

[0114] 4. Integrated Access and Backhaul (IAB):

[0115] An IAB network includes an IAB node (also called a relay node) and an IAB donor. The IAB node may provide wireless access services to user equipment (UE), and service data of the UE is transmitted to the IAB donor by the IAB node through a wireless backhaul link. The IAB node may access the IAB donor or may be connected to the IAB donor through another IAB node.

[0116] An IAB node may include at least one mobile terminal (MT) and at least one distributed unit (DU).

[0117] When an IAB node is directed to its parent node (which may be an IAB donor or another IAB node), the IAB node may be used as a terminal device, i.e., in the role of a terminal of the IAB-node. In this case, an MT function or an MT entity provides the IAB node with the role of a terminal. When an IAB node is directed to its child node (which may be another IAB node or a general UE), the IAB node may be used as a network device, i.e., in the role of a network device of the IAB node. In this case, a DU function or a DU entity provides the IAB node with the role of a network device.

[0118] The IAB donor is an access network element with complete base station functionality. It may include one central unit (CU) and at least one distributed unit (DU). The interface between the CU and the DU is an F1 interface. The IAB donor is connected to the core network that serves the UE.

[0119] For ease of explanation, in the following embodiments of this application, the MT of an IAB node is referred to as IAB-MT for short, and the DU of an IAB node is referred to as IAB-DU for short. One transmission path between a terminal device and an IAB donor may include one or more IAB nodes. Each IAB node needs to maintain a wireless backhaul link (BL) directed to its parent node and a wireless link directed to its child node. If the child node of an IAB node is a terminal device, the wireless link between the IAB node and the child node (i.e., the terminal device) is a wireless access link (AL). If the child node of an IAB node is another IAB node, the wireless link between the IAB node and the child node (i.e., another IAB node) is a wireless backhaul link.

[0120] Based on the above explanation, it is not difficult to see the similarities between NCR and IAB. From a functional perspective, both NCR and IAB are relays that can improve network coverage. From the UE's perspective, the UE is unaware of the existence of either NCR or IAB nodes. In IAB, the UE does not distinguish between the IAB-DU and the DU of other general base stations. The UE can access the network provided that it accesses the DU and the IAB backhaul link is invisible to the UE. In NCR, the UE is unaware of the existence of NCR. NCR-Fwd transparently amplifies and forwards physical signals and is invisible to the UE. NCR-MT is used by the network side to control NCR-Fwd and is invisible to the UE.

[0121] The differences between NCR and IAB are as follows:

[0122] In terms of hop count, IAB is more complex and supports features such as multi-hop, dual connectivity and IAB node mobility. NCR is a single-hop fixed repeater.

[0123] From an architectural perspective, the IAB node includes a DU and has the functionality of the upper layer protocol stack. New cells may be created by the DU. The cell served by the IAB-DU may be configured by the donor CU through the F1 interface. The cell created by the IAB-DU (serving the UE) and the parent node cell accessed by the IAB-MT are two cells. The donor CU configures the two cells separately. However, the NCR-Fwd does not create new cells, but only amplifies and forwards existing cell signals. Cell-level configuration (e.g., cell identifier configuration) cannot be performed for the NCR-Fwd; only physical signal-level configuration (e.g., beam steering) can be performed for the NCR-Fwd.

[0124] In terms of connectivity, the backhaul link of the IAB node is on the IAB-MT, and all data transmitted between the IAB-DU and the parent node and between the IAB-DU and the IAB donor must pass through the IAB-MT. However, in NCR, there is an NCR backhaul link between the NCR-Fwd and the base station, and there is an NCR-MT control link between the NCR-MT and the base station, not a backhaul link.

[0125] 5.IAB-MT Initial Access Procedures:

[0126] The initial access procedure of the IAB-MT is similar to the initial access procedure of a general UE. For a general UE, the initial access procedure generally includes the following steps:

[0127] (1) Search for the frequency.

[0128] When powered on, if the UE does not store cell frequency information (e.g., in a scenario where the UE is powered on for the first time in a cell), the UE scans all frequencies on the supported frequency band. If the UE stores previously found cell frequency information (e.g., in a scenario where the UE is powered off and then powered on again in a cell), the UE searches the previously stored cell frequencies.

[0129] For example, a base station (e.g., a next-generation NodeB (gNB)) transmits a synchronization signal and a physical broadcast channel (PBCH) block (SSB) for each cell on the corresponding frequency of the cell, and the UE can select the SSB with the best signal quality through scanning.

[0130] The SSB includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a PBCH.

[0131] For example, SSB may be carried by using an SSB beam. Therefore, in this embodiment of the application, transmitting an SSB by a base station may alternatively be understood as transmitting an SSB beam, and receiving an SSB by a UE may alternatively be understood as receiving an SSB beam. SSB and SSB beam may be interchangeable. In the spatial domain, both SSB transmission and reception are periodically scanned.

[0132] (2) Obtain the physical cell identifier (PCI) and master information block (MIB).

[0133] For example, the UE may determine the PCI based on the PSS and SSS in the SSB selected by the UE in step (1). The PCI and frequency may uniquely identify a cell. Therefore, after determining the PCI, the UE may know the cell selected by the UE. Furthermore, the UE may further decode the PBCH in the SSB to obtain the MIB of the cell. The MIB defines the most basic system information of the cell and the parameters required to obtain system information block 1 (SIB1).

[0134] (3) Obtain SIB1.

[0135] For example, the MIB includes time-frequency location information of a physical downlink control channel (PDCCH). After reading the MIB, the UE may monitor the PDCCH at the corresponding time-frequency location and read downlink control information (DCI) in the PDCCH. The DCI indicates the time-frequency location of a physical downlink shared channel (PDSCH) carrying SIB1, so that the UE may receive the PDSCH at the corresponding time-frequency location to receive SIB1.

[0136] (4) Select a public land mobile network (PLMN) and initiate random access.

[0137] The PLMN may be understood as an operator identifier (ID), and different PLMN values ​​correspond to different operators. The UE may select a corresponding operator network (i.e., a PLMN) based on subscription information.

[0138] For example, SIB1 includes PLMNs supported by the cell. After acquiring SIB1, the UE may know the PLMNs supported by the current cell. If the PLMNs supported by the current cell include the PLMN selected by the UE, the UE initiates random access within the current cell. SIB1 includes the random access channel configuration required for random access. If the current cell does not support the PLMN selected by the UE, the UE returns to step (1) to reselect another SSB to select another cell.

[0139] (5) Set up an RRC connection, register with the core network, and set up the UE context.

[0140] For example, the random access procedure includes an RRC connection setup process between the UE and the base station. After the random access is completed, the UE may send an RRC Setup Complete message to the base station, which carries the PLMN selected by the UE in step (4) for the network side to verify whether the UE is authorized.

[0141] After receiving the RRC setup complete message, the base station queries an access and mobility management function (AMF) network element corresponding to the PLMN selected by the UE and sends an NG interface message, such as an INITIAL UE MESSAGE, to the AMF network element, which carries the UE's identity and capability information. After receiving the NG interface message, the AMF network element and other core network elements complete UE authentication, non-access stratum (NAS) security registration, etc., and set up a UE context on the core network side. The NG interface may be an interface between a radio access network and a core network, for example, an interface between a gNB (or CU) and an AMF network element.

[0142] Then, the AMF network element sends an INITIAL CONTEXT SETUP REQUEST message to the base station to set up a UE context on the radio access network (RAN) side. Furthermore, the base station configures a signaling radio bearer (SRB) and a data radio bearer (DRB) for the UE. In this case, the UE may set up a protocol data unit (PDU) session with the core network based on service requirements to perform data transmission.

[0143] The difference between the IAB-MT initial access procedure and a general UE initial access procedure is that after selecting a PLMN, the IAB-MT also needs to read the IAB-support information element in SIB1, which indicates whether the cell supports IAB-MT access. The iab-support information element is an enumeration type and includes two cases: present (indicating that the cell supports IAB-MT access) and absent (indicating that the cell does not support IAB-MT access).

[0144] The iab-support information element is configured at the granularity of PLMN (i.e., per PLMN). SIB1 is configured with an iab-support value for each PLMN supported by the cell. During the initial access procedure, a general UE ignores the iab-support information element, and the IAB-MT reads the iab-support information element corresponding to the PLMN selected by the IAB-MT. If the value of the iab-support information element is present, the IAB-MT may select the current cell for access. If the value of the iab-support information element is absent, the IAB-MT may reselect another cell. For example, the reason a cell does not support the IAB service may be that the donor CU has not been upgraded to a CU that supports IAB capabilities, or that the operator does not expect to support the IAB service in the cell from a deployment perspective.

[0145] In a scenario where a cell belongs to (or supports) only one operator (one PLMN), configuring the iab-support information element at the PLMN granularity has the same effect as configuring the iab-support information element at the cell granularity (i.e., per cell). However, in a RAN sharing scenario, multiple operators are co-located. A cell may belong to (or support) multiple operators (PLMNs), i.e., a cell may support access for UEs of multiple operators. In this case, the iab-support information element is configured at the PLMN granularity, so that different operators can independently decide whether they support IAB services, i.e., whether they support IAB-MT access.

[0146] For example, a cell is shared by two operators, i.e., Operator 1 (PLMN1) and Operator 2 (PLMN2), i.e., the cell supports PLMN1 and PLMN2. If Operator 1 expects UEs that select Operator 1 to enjoy the IAB service of the cell, and Operator 2 does not expect or is not allowed to support the IAB service in the cell, the iab-support information element for PLMN1 may be set to present, and the iab-support information element for PLMN2 may be set to absent. In this way, only the IAB-MT of Operator 1 can access the cell. Furthermore, the donor CU may further control the SIB1 broadcast by the IAB-DU in the cell generated by the IAB-DU to indicate that the cell supports only PLMN1. In this way, only UEs that select PLMN1 can access via the IAB-DU and enjoy the IAB service.

[0147] It can be understood that if the SIB1 broadcasted by the IAB-DU in a cell generated by the IAB-DU indicates that the cell supports PLMN1 and PLMN2, a UE that selects PLMN2 may also perform access via the IAB-DU and enjoy IAB services. Therefore, the SIB1 broadcasted by the IAB-DU needs to be restricted to indicate that the cell supports only PLMN1.

[0148] IAB was introduced in 3GPP Release (R) 16, and the IAB node is similar to NCR. Therefore, in R-18 NCR subject research, IAB is used as a baseline for research as usual. For example, in the RAN2#120 meeting, it was agreed to introduce the NCR-support information element, which is configured at the PLMN granularity, and the IAB-MT initial access procedure is still used for NCR.

[0149] Furthermore, as shown in FIG. 3, the differences between the initial access of IAB-MT and NCR and the initial access of a general UE are as follows:

[0150] The AMF network element may include an indication in the NG interface setup response (NG SETUP RESPONSE) message in the NG interface setup process indicating whether the AMF network element supports IAB or NCR functionality, so that when selecting an AMF network element for IAB-MT or NCR-MT, the gNB may select an AMF network element that supports IAB or NCR functionality.

[0151] The IAB-MT or NCR-MT may include IAB or NCR indication information in the RRC setup complete message to indicate the IAB-MT or NCR-MT. The initial UE message (INITIAL UE MESSAGE) sent by the gNB to the AMF network element also carries the IAB or NCR indication information.

[0152] After the core network completes the authentication, when the AMF network element sends an INITIAL CONTEXT SETUP REQUEST message to the gNB to request that the RAN side set up a UE context, or sends a UE CONTEXT MODIFICATION REQUEST message to the gNB to request that the RAN side modify the UE context, the INITIAL CONTEXT SETUP REQUEST message or the UE CONTEXT MODIFICATION REQUEST message also carries IAB or NCR indication information to indicate to the RAN side that authentication for IAB-MT or NCR-MT has been completed.

[0153] It should be noted that Figure 3 merely provides an example of a general procedure by which an IAB-MT or NCR-MT performs initial access. The initial access procedure of an IAB-MT or NCR-MT is not limited to what is explicitly shown in Figure 3 in this application, and may include more or fewer steps than those in Figure 3.

[0154] 6. Non-public network (NPN):

[0155] The purpose of introducing NPN is to realize some of the functions of a non-public network (i.e., a "private network") via an operator's public network (PLMN). The identity of the NPN includes the identity of the PLMN and the identity of the closed access group (CAG). The CAG is a layer of identity below the PLMN, and one PLMN may contain multiple CAGs.

[0156] For example, a typical NPN is an enterprise campus network or campus network. A related unit (e.g., University A) may cooperate with an operator to configure some base station cells within the unit as CAG-cells or CAG-only cells. A CAG-cell allows access by UEs of a general PLMN and corresponding CAG UEs (e.g., UEs with University A's customized subscriber identity module (SIM) card inserted), but does not allow access by other CAG UEs (e.g., UEs with University B's customized SIM card inserted). A CAG-only cell allows access only by corresponding CAG UEs, but does not allow access by UEs of a general PLMN or other CAG UEs. This is a stricter access control.

[0157] The CAG information that the UE is allowed to access (e.g., the allowed CAG list) belongs to the UE's subscription information and is bound to the UE's SIM card. The information may be modified by the core network. The relevant modification operations are configured by the core network for the UE, and the RAN side does not analyze the information.

[0158] In an NPN, the PLMN information element in SIB1 may include a CAG information element, which indicates multiple CAGs included in the PLMN. A UE (also called a CAG UE or NPN UE) configured in the allowed CAG list adds a CAG selection process when selecting a PLMN. If the CAG of the PLMN includes a CAG corresponding to the UE, the UE selects the PLMN.

[0159] A UE that is not configured in the allowed CAG list (i.e., a general UE) reads the cellReservedForOtherUse information element in SIB1. If the cell is a CAG-only cell, this field is set to true; if the cell is a CAG cell, this field is set to false. If a general UE finds that the cellReservedForOtherUse information element is set to true, it considers the current cell to be a cell reserved for other UEs and does not access the cell. If a general UE finds that the cellReservedForOtherUse information element is set to false, it ignores the CAG decision and continues to perform PLMN selection, i.e., the UE may access the CAG cell as a general LMN UE.

[0160] For example, Table 1 shows an example of PLMN and CAG information broadcast by a cell. It can be seen from Table 1 that PLMN1 and PLMN2 each have an entry where the CAG ID is empty (represented by using -), so the cells are CAG cells but not CAG-only cells. [Table 1]

[0161] In NPN, the network side needs to perform access control to prevent malicious UEs from violating the rules. As shown in Figure 4, the UE may include a network index selected by the UE in an RRC Setup Complete message, and the gNB may send the network index to an AMF network element in an Initial UE message, so that the AMF network element performs access control. For example, the AMF network element may obtain the UE's allowed CAG list from a unified data management (UDM) network element and determine whether a CAG ID corresponding to the UE's selected network index is in the UE's allowed CAG list.

[0162] If the CAG ID is in the UE's allowed CAG list, the check is successful and the UE's allowed CAG list is sent to the gNB in ​​the initial context setup request message, so that the gNB exchanges the UE's CAG information with the target base station during the UE's cell handover process. If the CAG ID is not in the UE's allowed CAG list, the AMF network element denies the UE access.

[0163] In other words, in an NPN, when a UE is expected to access a CAG cell or a CAG-only cell, both the UE and the AMF network element need to determine CAG-related constraints, and only UEs that meet the CAG-related constraints can access the CAG cell or the CAG-only cell.

[0164] In the R16 IAB, the IAB-MT may also support NPN functionality, and the IAB-MT must also consider CAG constraints during access. Based on this, only certain IAB nodes (e.g., IAB nodes purchased by a unit) can access CAG-only cells. In the current NCR discussion, the NCR-MT may also support NPN functionality.

[0165] 7. RRC Idle (RRC_IDLE) state:

[0166] If the UE does not perform service transmission for a long time, the UE will enter the RRC idle state. For a UE in the RRC idle state, both the RAN side and the core network side will release the UE context.

[0167] When the UE intends to perform service transmission, the UE may initiate an RRC connection setup request to return to the active RRC connected state. Alternatively, when the core network receives the service request of the UE, the core network may trigger a paging message to wake up the UE to the RRC connected state.

[0168] The 5G system is used as an example. In the paging message, the UE may be identified by using the UE's 5G system temporary mobile subscriber identity (5G-S-TMSI). The 5G-S-TMSI is initially generated by the UE. The UE reports the UE's 5G-S-TMSI to the gNB in ​​the RRC setup process, and then the gNB reports the 5G-S-TMSI to the core network.

[0169] For security purposes, the UE's 5G-S-TMSI value is not permanent and may change. The new 5G-S-TMSI value is generated by the AMF network element and notified to the UE using an NAS message. The RAN side does not analyze the new 5G-S-TMSI value.

[0170] Currently, in the NCR standard discussion, it is considered that to achieve NCR energy saving, when the gNB does not need to frequently transmit control information to the NCR-MT, the gNB may release the NCR-MT to the RRC idle state. In this case, the NCR is downgraded to an NR repeater and no longer receives network control. The NCR-Fwd may continue to operate based on the latest configuration, i.e., the NCR-Fwd operates based on a fixed configuration.

[0171] 8. NG Interface Application Protocol (next generation application, NGAP) ID:

[0172] The UE NGAP ID identifies the UE with which the NG interface message is associated. For example, the UE NGAP ID includes an AMF UE NGAP ID assigned by the AMF network element and a RAN UE NGAP ID assigned by the RAN side.

[0173] When the UE performs initial access, the UE's first NG interface message (e.g., INITIAL UE MESSAGE) sent by the gNB to the AMF network element carries the RAN UE NGAP ID. The AMF network element then assigns the AMF UE NGAP ID to the UE and includes the mapping relationship between the AMF UE NGAP ID and the RAN UE NGAP ID in the initial context setup request message sent to the gNB.

[0174] Then, when the gNB and the AMF network element exchange messages for the UE again, both the gNB and the AMF network element need to carry the AMF UE NGAP ID and / or the RAN UE NGAP ID to identify the UE associated with the message.

[0175] As mentioned above, currently, IAB is usually used as a baseline for NCR research, and the related implementation of the IAB node is used for NCR. However, the differences between NCR and IAB nodes make it impossible to completely copy the related implementation of the IAB node for NCR. An example is as follows.

[0176] Similar to iab-support, configuring NCR-support at the PLMN granularity does not ensure that only UEs that select a specific PLMN can enjoy NCR service. This is because NCR-Fwd only transparently amplifies and forwards physical signals and cannot distinguish between PLMNs. For example, in SIB1, NCR-support for PLMN1 is set to present and NCR-support for PLMN2 is set to absent. In this case, the NCR-MT in PLMN1 is allowed to access the network and the NCR-MT in PLMN2 is prevented from accessing the network, but the NCR in PLMN1 cannot deny access to UEs that select PLMN2 via NCR. In other words, UEs that select PLMN2 ultimately still enjoy NCR service.

[0177] However, in IAB, the reason why only UEs within a specific PLMN can enjoy the IAB service is that the IAB node has a DU. In order to restrict UEs from selecting other PLMNs to access the IAB-DU, the donor CU may control the IAB-DU to broadcast that the PLMNs supported by the cell are PLMNs that the IAB-MT is allowed to access.

[0178] In other words, in an NCR scenario, how to allow UEs that select some PLMNs to perform access via NCR and how to deny UEs that select other PLMNs from accessing via NCR is currently an issue that needs to be urgently resolved.

[0179] Furthermore, unlike IAB-DU, NCR-Fwd does not generate new cells, but is configured to transparently amplify and forward physical signals. Even if an NCR-MT that does not satisfy the NPN constraints is allowed to access a CAG-only cell (e.g., an NCR-MT without an allowed CAG list configured accesses a CAG-only cell), the NPN access control result of any UE is not changed (because NPN access control is realized by an AMF network element). Furthermore, if the NCR-MT needs to determine the NPN constraints during access, the cost and complexity of NCR production will increase, and an NCR containing a specific MT will need to be produced for a specific NPN cell. This does not lead to widespread deployment of NCR.

[0180] Furthermore, for a UE in RRC idle state, currently, paging needs to be triggered via the core network to wake up the UE, and the gNB cannot wake up the UE from the RRC idle state. Therefore, when the gNB actively releases the NCR-MT to the RRC idle state, the gNB cannot wake up the NCR-MT again in the RRC idle state. As a result, the gNB cannot regain control of the NCR.

[0181] Based on the above analysis, this application provides a communication method for designing the relevant implementation scheme of NCR to facilitate the normal operation of NCR.

[0182] 5 is a diagram of the structure of a communication system to which the method according to this application can be applied. The communication system includes at least one access network device, at least one repeater, and at least one terminal device. Optionally, the communication system may further include a mobility management network element.

[0183] Optionally, repeaters are deployed in the cells of the access network devices, and the access network devices may control the repeaters. The repeaters may be configured to, for example, amplify and forward signals to improve the coverage area of ​​the access network devices. Terminal devices may communicate with the access network devices through the repeaters or may communicate directly with the access network devices over the air interface.

[0184] For example, in this embodiment of this application, a cell served by an access network device may alternatively be understood as a cell managed by the access network device, and the two descriptions may be interchangeable.

[0185] Optionally, the repeater may be an NCR, or may be a derivative device of an NCR, such as a relay device that supports fewer or more functions than those supported by an NCR. In this embodiment and in FIG. 5 of this application, an example in which the repeater is an NCR is used for explanation.

[0186] Optionally, an access network device is a device that connects a terminal device to a wireless network, and may be a node in a RAN, may be called a base station, or may be called a radio access network node (or device).

[0187] For example, the access network device may include an evolved NodeB (NodeB or eNB or e-NodeB, evolutional NodeB) in a long term evolution (LTE) system or an LTE-advanced (LTE-A) system, such as a conventional macro base station eNB and a micro base station eNB in ​​a heterogeneous network scenario. Alternatively, the access network device may include a next generation NodeB (gNB) in an NR system. Alternatively, the access network device may include a transmission reception point (TRP), a home base station (e.g., a home evolved NodeB or home NodeB, HNB), a baseband unit (BBU), a baseband pool (BBU pool), a wireless fidelity (Wi-Fi) access point (AP), etc. Alternatively, the access network device may include a base station in a non-terrestrial network (NTN), i.e., deployed on an airborne platform or a satellite. In NTN, an access network device may be used as a Layer 1 (L1) relay, a base station, or an integrated access and backhaul (IAB) node. Alternatively, the access network device may be a device that implements the functions of a base station in the Internet of Things (IoT), such as unmanned aerial vehicle communications, vehicle-to-everything (V2X), device-to-device (D2D), or machine-to-machine (M2M).

[0188] Alternatively, the access network device may be a module or unit capable of implementing some functions of a base station. For example, the access network device may be a central unit (CU), a distributed unit (DU), a CU control plane (CP), a CU user plane (UP), or a radio unit (RU). The CU and DU may be located separately or may be included in the same network element, such as a baseband unit (BBU). The RU may be included in a radio frequency device or radio unit, such as a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[0189] In different systems, the CU (or CU-CP and CU-UP), DU, or RU may also have different names, but those skilled in the art will understand their meanings. For example, an access network device may be an access network device or a module of an access network device in an open radio access network (open RAN, ORAN) system. In an ORAN system, the CU may also be referred to as an open (O)-CU, the DU may also be referred to as an O-DU, the CU-CP may also be referred to as an O-CU-CP, the CU-UP may also be referred to as an O-CU-UP, and the RU may also be referred to as an O-RU. Any one of the CU (or CU-CP or CU-UP), DU, and RU in this application may be realized by using a software module, a hardware module, or a combination of a software module and a hardware module.

[0190] Optionally, the CU and DU may be obtained through division based on protocol layers of a wireless network. For example, functions of a packet data convergence protocol (PDCP) layer and protocol layers above the PDCP layer (e.g., a radio resource control (RRC) layer and a service data adaptation protocol (SDAP) layer) are configured in the CU, and functions of protocol layers below the PDCP layer (e.g., a radio link control (RLC) layer, a media access control (MAC) layer, or a physical (PHY) layer) are configured in the DU. In another example, functions of protocol layers above the PDCP layer are configured in the CU, and functions of the PDCP layer and protocol layers below the PDCP layer are configured in the DU. This is not limited thereto.

[0191] The division of the processing functions of the CU and the DU based on the protocol layer is merely an example, and other division schemes may alternatively be used. For example, the CU or DU may have more protocol layer functions through division. In another example, the CU or DU may have some processing functions of the protocol layer through division. For example, some functions of the RLC layer and functions of the protocol layer above the RLC layer are assigned to the CU, and the remaining functions of the RLC layer and functions of the protocol layer below the RLC layer are assigned to the DU. In another example, the division of the functions of the CU or DU may alternatively be performed based on service type or other system requirements. For example, the division may be performed based on delay. Functions whose processing time must meet delay requirements are assigned to the DU, and functions whose processing time does not need to meet delay requirements are assigned to the CU.

[0192] Optionally, the terminal device in the embodiments of this application may be a user-side device configured to realize wireless communication functions, such as a terminal or a chip that may be used in a terminal. The terminal may be a user equipment (UE), an access terminal, a terminal unit, a terminal station, a mobile station, a remote station, a remote terminal, a mobile device, a wireless communication device, a terminal agent, a terminal device, etc. in a 5G network or a future evolved PLMN after a 5G network. An access terminal may be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless communication capabilities, a computing device or other processing device connected to a wireless modem, an in-vehicle device, an unmanned aerial vehicle, a robot, a smart point of sale (POS) machine, a customer-premises equipment (CPE) or wearable device, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, etc. Alternatively, the terminal may be a terminal having a communication function in IoT, such as a terminal in V2X (e.g., a vehicle Internet device), a terminal in D2D communication, or a terminal in M2M communication. The terminal may be mobile or fixed.

[0193] Optionally, the mobility management network element is mainly responsible for signaling processing functions, such as access control, mobility management, attach and detach, and gateway selection. In a 5G communication system, the mobility management network element may be an AMF network element. In future communication systems, the mobility management network element may still be an AMF network element, or may have other names. This is not limited in this embodiment of the application.

[0194] The methods provided in the embodiments of this application will be described below with reference to the accompanying drawings. It may be understood that in the embodiments of this application, an executing entity may perform some or all of the steps in the embodiments of this application. The steps or operations are merely examples. In the embodiments of this application, other operations or variations of operations may also be performed. Furthermore, the steps may be performed in an order different from that presented in the embodiments of this application, and all operations in the embodiments of this application may not be performed.

[0195] It should be noted that in the following embodiments of this application, the names of messages between functions or entities, the names of various pieces of information in the messages, etc. are merely examples, and other names may exist in a specific implementation, which is not particularly limited in the embodiments of this application.

[0196] 6 shows a communication method according to an embodiment of this application. The communication method includes the following steps:

[0197] S601: A first access network device determines indication information.

[0198] The indication information indicates a PLMN corresponding to a first SSB of a first cell, for example, the first cell may be a cell served by a first access network device.

[0199] Optionally, an NCR may be deployed in the coverage area of ​​the first cell. For ease of description, in this embodiment, the NCR deployed in the coverage area of ​​the first cell is referred to as the first NCR.

[0200] Optionally, there may be N SSBs in the first cell, where N is a positive integer equal to or greater than 1. Each of the N SSBs corresponds to an SSB index, and different SSBs correspond to different SSB indices. The SSB index may indicate the direction of an SSB beam. Specifically, the directions of the SSB beams corresponding to different SSBs among the N SSBs are different.

[0201] Optionally, the first SSB may be any SSB of the first cell, or the first SSB may be an SSB that can be forwarded by the first NCR. The SSB that can be forwarded by the first NCR may alternatively be understood as an SSB that can be received by the first NCR, or the first NCR being able to forward at least one SSB may alternatively be understood as the first NCR being deployed within the beam range of an SSB beam corresponding to at least one SSB. For example, as shown in FIG. 1, an NCR may be deployed in a specific location and be able to receive only some SSBs of the cell. Therefore, the NCR may be able to forward only SSBs received by the NCR.

[0202] Optionally, for example, the first SSB is an SSB that can be transferred by the first NCR. In addition to the first SSB, the indication information may further indicate PLMNs corresponding to other SSBs that can be transferred by the first NCR. For example, the SSBs that can be transferred by the first NCR may include SSB1 and SSB2, and the indication information may indicate the PLMNs corresponding to SSB1 and SSB2, respectively.

[0203] Optionally, for example, the first SSB is any SSB of the first cell. In addition to the first SSB, the indication information may further indicate PLMNs corresponding to other SSBs of the first cell. For example, N may be equal to 8, and the indication information may indicate PLMNs corresponding to each of the eight SSBs of the first cell.

[0204] Optionally, the SSB's support for a PLMN may be understood as the SSB supporting a terminal device that selects a PLMN when performing initial access. For example, the terminal device that selects a PLMN may perform random access based on a random access-related configuration, such as a random access resource configured in the SSB.

[0205] In other words, the first SSB is used as an example. If the PLMN corresponding to the first SSB includes the first PLMN, the first SSB supports a terminal device that selects the first PLMN when performing initial access. If the PLMN corresponding to the first SSB does not include the first PLMN, the first SSB does not support a terminal device that selects the first PLMN when performing initial access.

[0206] Optionally, one SSB may correspond to at least one PLMN, and the indication information may include an identifier of the SSB and identification information of the PLMN corresponding to the SSB.

[0207] For example, the indication information may include an information element {SSB index, allowed PLMN set}, where the allowed PLMN set includes at least one PLMN identity.

[0208] S602: The first access network device transmits system information of the first cell. Correspondingly, the first terminal device receives the system information of the first cell.

[0209] The system information includes the indication information determined in step S601. For example, the system information may be MIB or SIB1, that is, the first access network device broadcasts the PLMN corresponding to the SSB in the MIB or SIB1 of the first cell.

[0210] S603: The first terminal device determines a PLMN corresponding to the first SSB based on the indication information.

[0211] Optionally, after receiving the system information of the first cell, the first terminal device may read the indication information in the system information and determine the PLMN corresponding to the first SSB according to the indication of the indication information. After determining the PLMN corresponding to the first SSB, the first terminal device may perform some processing.

[0212] For example, the SSB selected by the first terminal device in the initial access procedure is the first SSB, and the PLMN selected by the first terminal device is the first PLMN. After the first terminal device determines the PLMN corresponding to the first SSB, if the PLMN corresponding to the first SSB includes the first PLMN, the first terminal device may continue to perform initial access based on the first SSB, for example, perform random access based on the first SSB. If the PLMN corresponding to the first SSB does not include the first PLMN, this indicates that the first SSB does not support terminal devices that select the first PLMN when performing initial access. In this case, the first terminal device may reselect another SSB (denoted as the fifth SSB) of the first cell and perform initial access based on the fifth SSB.

[0213] Optionally, if the indication information further indicates a PLMN corresponding to an SSB other than the first SSB of the first cell, the first terminal device may select an SSB whose corresponding PLMN includes the first PLMN based on the indication information to complete the initial access. In other words, the indication information further indicates a PLMN corresponding to a fifth SSB, and the PLMN corresponding to the fifth SSB includes the first PLMN.

[0214] For example, assume that the indication information indicates that SSB1 corresponds to PLMN1, SSB2 corresponds to PLMN2, and the first NCR can forward SSB1 but cannot forward SSB2. In other words, the first NCR can provide relay services to terminal devices that select PLMN1 but cannot provide relay services to terminal devices that select PLMN2.

[0215] If the SSB selected by the first terminal device in the initial access procedure is SSB1 and the PLMN selected by the first terminal device is PLMN2, the first terminal device may know based on the indication information that the PLMN corresponding to SSB1 is PLMN1 and not PLMN2, i.e., that SSB1 supports access only for terminal devices that select PLMN1 and does not support access for terminal devices (including the first terminal device) that select PLMN2. In this case, the first terminal device may select another SSB of the first cell to complete the access. For example, the first terminal device may know based on the indication information that the PLMN corresponding to SSB2 is PLMN2. Therefore, the first terminal device may select SSB2 to complete the access.

[0216] Optionally, when the first terminal device learns based on the indication information that the PLMNs corresponding to the multiple SSBs each include PLMN2, the first terminal device may select an SSB with the best signal quality from the multiple SSBs to complete the access.

[0217] Based on the above solution, the access network device may broadcast the PLMN corresponding to the SSB in the system information, so that the terminal device receiving the system information can know the correspondence between the SSB and the PLMN, and perform related processing based on the correspondence.

[0218] For example, the terminal device may determine, based on the correspondence between the SSB and the PLMN and the SSB and PLMN selected by the terminal device, to continue completing the initial access based on the SSB selected by the terminal device or to reselect an SSB. For example, if the PLMN corresponding to the SSB selected by the terminal device includes the PLMN selected by the terminal device, the terminal device continues to complete the initial access based on the SSB selected by the terminal device, or if the PLMN corresponding to the SSB selected by the terminal device does not include the PLMN selected by the terminal device, the terminal device reselects the SSB.

[0219] Based on this, a specific PLMN is configured for SSBs that can be forwarded by the NCR, allowing terminal devices that select the specific PLMN to access the network via the NCR and denying terminal devices that select other PLMNs from accessing the network via the NCR, thereby allowing the NCR to serve terminal devices that select the specific PLMN and improving the operator's control over the NCR.

[0220] Optionally, for a terminal device accessing the first cell, the access network device may know the SSB and PLMN selected by the terminal device. For example, since there is a correspondence between the SSB and the random access resource, the access network device may determine the SSB selected by the terminal device based on the random access resource used by the terminal device to perform random access. The PLMN selected by the terminal device may be reported by the terminal device to the access network device after the random access is completed.

[0221] Optionally, the access network device may know the SSBs that can be transferred by the NCR. When the SSBs that can be transferred by the NCR include the SSB selected by the terminal device, the access network device may determine that the terminal device performs access via the NCR. Then, the network device may check whether the PLMN corresponding to the SSB selected by the terminal device includes the PLMN reported by the terminal device (i.e., the PLMN selected by the terminal device).

[0222] If the PLMN corresponding to the SSB selected by the terminal device does not include the PLMN reported by the terminal device, this indicates that the terminal device does not comply with the correspondence between the SSB and the PLMN broadcasted by the access network device, in which case the access network device may deny the terminal device access via NCR, for example, release the RRC connection, or perform beam switching.

[0223] For example, assume that SSB1 corresponds to PLMN1, SSB2 corresponds to PLMN2, and NCR can transfer SSB1 but cannot transfer SSB2. If the SSB selected by the terminal device in the initial access procedure is SSB1 and the PLMN selected by the terminal device is PLMN2, but the terminal device still performs initial access based on SSB1, the access network device may find through the above check that the terminal device does not comply with the correspondence between the SSB and the PLMN, i.e., the terminal device that does not belong to the service area of ​​the NCR still accesses the network via the NCR. Therefore, the access network device may deny the terminal device's access via the NCR. As a result, the terminal device no longer receives the service of the NCR.

[0224] Based on this solution, the case where a terminal device that does not belong to the service area of ​​the NCR accesses the network through the NCR is avoided, and the operator's control ability over the NCR can be further improved.

[0225] It should be noted that in this application, the method shown in FIG. 6 is not limited to being applied to communication scenarios in which NCRs are deployed, but may also be applied to other communication scenarios, for example, communication scenarios in which no relay system is involved, or communication scenarios in which other relay devices different from NCRs are deployed.

[0226] In addition to the method shown in Figure 6, the embodiment of this application further provides another communication method. As shown in Figure 7, the communication method includes the following steps:

[0227] S701: A first terminal device sends first information to a first access network device. Correspondingly, the first access network device receives the first information from the first terminal device.

[0228] Optionally, before step S701, the first terminal device performs an initial access procedure to access the first access network device, for example, to access the first cell of the first access network device.

[0229] Optionally, the first terminal device may access the first cell via a first NCR controlled by the first access network device. Therefore, the first information may alternatively be forwarded to the first access network device by the first NCR (the first terminal device is unaware of the first information). In other words, the first access network device receiving the first information from the first terminal device includes: the first access network device receives the first information from the first terminal device via the first NCR.

[0230] The first information indicates a first PLMN, which is a PLMN selected by the first terminal device in an initial access procedure.

[0231] Optionally, the first information may be carried in an RRC Setup Complete message. In other words, the first terminal device sends an RRC Setup Complete message to the first access network device, and the RRC Setup Complete message carries the first information.

[0232] Optionally, after receiving the first information, the first access network device may determine whether the first NCR supports the first PLMN. If the first NCR supports the first PLMN, this indicates that the first terminal device is authorized to enjoy the relay service provided by the first NCR, and the first terminal device may perform normal access via the first NCR. If the first NCR does not support the first PLMN, this indicates that the first terminal device is not authorized to perform access via the first NCR. In this case, the following step S702 may be performed.

[0233] Optionally, for each terminal device accessing the first access network device, the first access network device may determine whether the terminal device accesses the first access network device through the first NCR, for example, based on the SSB selected by the terminal device. For details, see the related description above. For terminal devices that perform access through the first NCR, the first access network device performs step S702. Specifically, before step S702, the first access network device may determine that the first terminal device accesses the first access network device through the first NCR.

[0234] S702: If the first NCR does not support the first PLMN, the first access network device denies the first terminal device access via the first NCR.

[0235] In other words, if the first NCR does not support the first PLMN, the first access network device denies the first terminal device access to the first cell or the first access network device via the first NCR.

[0236] Optionally, the first NCR not supporting the first PLMN may alternatively be understood as the first NCR not serving the first PLMN or the first NCR not serving a terminal device that selects the first PLMN, and the three descriptions may be interchangeable.

[0237] In a first possible implementation manner, if the PLMNs supported by the first NCR do not include the first PLMN, the first NCR does not support the first PLMN. In other words, if the PLMNs supported by the first NCR do not include the first PLMN, the first access network device denies the first terminal device access via the first NCR.

[0238] Optionally, the PLMNs supported by the first NCR may be reported to the first access network device by the first NCR. For example, before step S702, the first NCR may send second information to the first access network device, and the first access network device correspondingly receives the second information from the first NCR. The second information indicates at least one PLMN supported by the first NCR. For example, the second information includes identification information of at least one PLMN supported by the first NCR.

[0239] For example, as shown in FIG. 8, a MT of a first NCR (denoted as NCR-MT) may select a cell (the first cell is used as an example) that supports the access of the NCR-MT, and after completing the initial access procedure in the first cell, the NCR-MT sends an RRC setup complete message to the first access network device, where the RRC setup complete message carries the second information.

[0240] Optionally, the first NCR may support multiple PLMNs. For example, in a RAN sharing scenario in which three operators share the first cell, if the first NCR is jointly purchased by two operators, the first NCR may serve the terminal devices of the two operators, that is, the PLMNs supported by the first NCR are PLMNs corresponding to the two operators.

[0241] Optionally, the first NCR may further report the PLMN selected by the MT in the initial access procedure to the access network device. For example, the selected PLMN and the second information may be carried in the same message, e.g., both are carried in the RRC Setup Complete message, or the selected PLMN and the second information may be carried in different messages, which is not particularly limited in this application.

[0242] Optionally, the PLMN selected by the MT of the first NCR in the initial access procedure may be carried in a selected PLMN-Identity information element, and the second information may be carried in a supported PLMN-Identity-List information element.

[0243] Based on this implementation, the second information is carried in the supportedPLMN-Identity-List instead of extending the selectedPLMN-Identity information element into the selectedPLMN-Identity list information element to carry at least one PLMN supported by the first NCR. This can help the first access network device determine the PLMN selected by the MT of the first NCR and select an AMF network element corresponding to the PLMN to perform registration for the MT of the first NCR. If the selectedPLMN-Identity list information element carries multiple PLMNs, the first access network device cannot select an AMF network element to perform registration for the MT of the first NCR, resulting in access failure of the MT of the first NCR.

[0244] In a second possible implementation manner, if the PLMN selected by the first NCR (NCR-MT) in the initial access procedure is different from the first PLMN, the first NCR does not support the first PLMN. In other words, if the PLMN selected by the first NCR (NCR-MT) in the initial access procedure is different from the first PLMN, the first access network device denies the first terminal device access via the first NCR.

[0245] Optionally, before step S702, the first NCR may report the PLMN selected by the MT in the initial access procedure to the access network device. For details, please refer to the related description of reporting the PLMN in the first possible implementation manner. The details will not be described again in this specification.

[0246] In a third possible implementation manner, if the first PLMN does not support NCR-MT access, the first NCR does not support the first PLMN. In other words, if the first PLMN does not support NCR-MT access, the first access network device denies the first terminal device access through the first NCR.

[0247] Optionally, the first terminal device accesses the first cell, and the PLMN selected by the first terminal device in the initial access procedure is the first PLMN, so the first PLMN is the PLMN of the first cell, and whether the first PLMN supports NCR-MT access may be configured by the first access network device. Thus, the first access network device may know whether the first PLMN supports NCR-MT access, and may determine whether the first NCR supports the first PLMN depending on whether the first PLMN supports NCR-MT access.

[0248] Optionally, as shown in Figure 8, before step S701, the first access network device may send system information (e.g., SIB1). The system information may indicate whether the first cell supports NCR-MT access, i.e., the first access network device configures an NCR-support information element at cell granularity (per cell). In this case, either all PLMNs supported by the first cell support NCR-MT access, or none of the PLMNs support NCR-MT access.

[0249] Alternatively, the system information may indicate whether each PLMN supported by the first cell supports NCR-MT access, i.e., the first access network device configures the NCR-support information element at the granularity of PLMN (per PLMN). In this case, some PLMNs supported by the first cell may support NCR-MT access, and other PLMNs may not support NCR-MT access, or all PLMNs may support NCR-MT access, or none of the PLMNs support NCR-MT access.

[0250] Optionally, when the first access network device configures the NCR-support information element at the granularity of a cell, the first access network device may determine whether the first NCR supports the first PLMN by using a first or second possible implementation manner.When the first access network device configures the NCR-support information element at the granularity of a PLMN, the first access network device may determine whether the first NCR supports the first PLMN by using a first, second, or third possible implementation manner.

[0251] Based on this implementation, whether the first cell supports NCR-MT access is configured at the granularity of the cell, thereby reducing signaling overhead. Furthermore, based on the first or second possible implementation, when configuration is performed at the granularity of the cell, whether the first PLMN supports NCR-MT access can also be determined. Whether each PLMN supports NCR-MT access is configured at the granularity of the PLMN, thereby improving configuration flexibility.

[0252] Based on the above solution, for a terminal device accessing a network via an NCR, the access network device may determine whether the NCR supports the PLMN selected by the terminal device. If the NCR does not support the PLMN selected by the terminal device, the access of the terminal device via the NCR is denied. In other words, through the control of the access network device, a terminal device that selects a PLMN supported by the NCR may be permitted to access the network via the NCR and enjoy the relay service provided by the NCR, while a terminal device that selects a PLMN not supported by the NCR may be denied to access the network via the NCR. Thus, the NCR provides services to terminal devices that select a specific PLMN, improving the operator's control over the NCR.

[0253] Optionally, in step S702, the first access network device may deny the first terminal device access via the first NCR in the following three ways:

[0254] Scheme 1: A first access network device performs beam switching to a first terminal device.

[0255] In other words, if the first NCR does not support the first PLMN, the first access network device performs beam switching for the first terminal device.

[0256] Optionally, after performing beam switching for the first terminal device, the first access network device may provide service to the first terminal device by using a beam that cannot be forwarded by the first NCR (i.e., a beam that cannot be received by the first NCR).

[0257] Manner 2: The first access network device sends an RRC message to the first terminal device. Correspondingly, the first terminal device receives an RRC message from the first access network device.

[0258] The RRC message is used to release the RRC connection between the first terminal device and the first access network device. For example, the RRC message may be an RRC Release (RRCRelease) message.

[0259] In other words, if the first NCR does not support the first PLMN, the first access network device sends an RRC message to the first terminal device, and the RRC message is used to release the RRC connection between the first terminal device and the first access network device.

[0260] Optionally, the RRC message may include third information. In a possible implementation, the third information indicates a second SSB, which is used for the next access of the first terminal device, and the SSBs that can be transferred by the first NCR do not include the second SSB. In other words, the first access network device instructs the first terminal device to select the second SSB during the next access. The PLMNs supported by the second SSB include the first PLMN. In this scenario, for example, the third information may be carried in a redirect carrier information (redirectCarrierInfo) information element.

[0261] Based on this possible implementation scheme, the first access network device indicates to the first terminal device the SSB to be selected during the next access, thereby avoiding the first terminal device still selecting an SSB that does not support the first PLMN to perform the next access, thereby reducing the access delay of the first terminal device and improving access efficiency.

[0262] In another possible implementation, the third information indicates a third SSB, which will not be used for the next access of the first terminal device and can be forwarded by the first NCR. After receiving the third information, the first terminal device may not measure the third SSB when performing measurements for the next access, and may select an SSB for access based on measurement results of other SSBs. In this scenario, for example, the third information may be carried in a banned carrier information (bannedCarrierInfo) information element.

[0263] Based on this possible implementation scheme, the first access network device indicates to the first terminal device an SSB that cannot be used for the first terminal device's access, thereby avoiding the first terminal device selecting an SSB that cannot be used for the first terminal device's access during the next access, thereby reducing the access delay of the first terminal device and improving access efficiency.

[0264] Manner 3: The first access network device performs a cell handover to the first terminal device.

[0265] In other words, if the first NCR does not support the first PLMN, the first access network device performs a cell handover for the first terminal device.

[0266] For example, as shown in FIG. 9, the first access network device performing cell handover to the first terminal device may include the following steps:

[0267] S901: A first access network device sends measurement configuration information to a first terminal device. Correspondingly, the first terminal device receives the measurement configuration information from the first access network device.

[0268] The SSBs that can be transferred by the second NCR are not present (or are excluded) in the measurement objects indicated by the measurement configuration information, and the PLMNs served (or supported) by the second NCR do not include the first PLMN.

[0269] For example, the SSBs that can be transferred by the second NCR include a fourth SSB. The measurement configuration information may include a measurement prohibition information element, and a frequency corresponding to the fourth SSB and an identifier of the fourth SSB are carried in the measurement prohibition information element. Then, when performing measurements on the frequency corresponding to the fourth SSB, the first terminal device may not measure the fourth SSB on the frequency.

[0270] Based on the configuration of the measurement object, the first terminal device does not measure the SSB that can be transferred by the second NCR, and therefore does not select the SSB, i.e., does not access the network via the second NCR, thereby avoiding the case where the first terminal device is rejected by the access network device after accessing the network via the second NCR, thereby improving cell handover efficiency.

[0271] Optionally, the second NCR includes an NCR other than the first NCR (deployed in a cell other than the first cell) controlled by the first access network device and / or an NCR controlled by the second access network device. For example, the first access network device may be understood as a source access network device for cell handover, and the second access network device may be understood as a target access network device for cell handover.

[0272] It should be noted that step S901 may be performed independently without depending on the method shown in Fig. 7. For example, step S901 may be applied to any scenario in which a measurement object needs to be configured, for example, any cell handover scenario.

[0273] Optionally, if the second NCR includes an NCR controlled by a second access network device, in a possible implementation, the SSBs that can be forwarded by at least one NCR controlled by the second access network device and / or the PLMNs served (or supported) by at least one NCR controlled by the second access network device may be configured for the first access network device via an operation, administration and maintenance (OAM) system.

[0274] If the second NCR includes an NCR controlled by a second access network device, in another possible implementation manner, the following step S900 may be further executed before step S901, as shown in FIG. 9.

[0275] S900: The second access network device sends fourth information to the first access network device. Correspondingly, the first access network device receives the fourth information from the second access network device.

[0276] The fourth information indicates SSBs that can be forwarded by at least one NCR controlled by the second access network device and / or PLMNs that are served (or supported) by at least one NCR controlled by the second access network device.

[0277] Optionally, the fourth information may be an XN interface setup request (XN SETUP REQUEST) message or an XN interface setup response (XN SETUP RESPONSE) message.

[0278] Optionally, the first access network device may alternatively send information to the second access network device to indicate SSBs that can be forwarded by at least one NCR controlled by the first access network device and / or PLMNs served (or supported) by at least one NCR.

[0279] Alternatively, step S900 may be performed independently without relying on the methods shown in Figures 7 and 9. In other words, information about the NCR (or NCR in a cell) controlled by the access network device (e.g., SSBs that can be forwarded by the NCR and / or PLMNs served by the NCR) may be exchanged between the access network devices as basic information of the cell. The scenario in which the access network devices exchange information is not limited in this application.

[0280] Optionally, step S900 is an optional step and may not be performed. In step S901, the first access network device may configure a measurement object for the first access network device according to the current prior art.

[0281] Optionally, after step S901, the cell handover procedure of the first terminal device may further include the following steps S902 to S904.

[0282] S902: The first terminal device sends a measurement report to the first access network device. Correspondingly, the first access network device receives the measurement report from the first terminal device.

[0283] Optionally, the measurement report may include PCI information measured by the first terminal device, an identifier of the measured SSB, and a measured signal strength of the SSB, which may be represented, for example, by using reference signal received power (RSRP) or reference signal received quality (RSRQ).

[0284] S903: The first access network device sends a handover request message to the second access network device. In response, the second access network device receives a handover request message from the first access network device.

[0285] Optionally, the handover request message includes an identifier of the target cell, an identifier of an SSB of the target cell measured by the first terminal device, a signal strength of the SSB measured by the first terminal device, and a PLMN selected by the first terminal device when the first terminal device accesses the first network device.

[0286] S904: The second access network device sends a handover request acknowledgment (Handover Request ACK) message to the first access network device. In response, the first access network device receives handover request acknowledgment information from the second access network device.

[0287] Optionally, the handover request acknowledgement message may include a random access resource allocated to the first terminal device by the second access network device based on an identifier of an SSB of the target cell measured by the first terminal device and a signal strength of the SSB measured by the first terminal device.

[0288] For example, when step S900 is executed and the measurement object indicated by the measurement configuration information in step S901 does not include an SSB that can be forwarded by the second NCR, the second access network device may allocate to the first terminal device a random access resource corresponding to the SSB with the highest signal strength measured by the first terminal device.

[0289] When step S900 is not performed and the first access network device configures a measurement object for the first access network device in step S901 according to the current prior art, the second access network device may first exclude SSBs that can be forwarded by the second NCR from the SSBs of the target cell measured by the first terminal device, and then allocate a random access resource corresponding to the SSB with the highest signal strength from the remaining SSBs to the first terminal device.

[0290] Optionally, after step S904, the first access network device may send the random access resource allocated to the first terminal device by the second access network device to the first terminal device. The first terminal device may initiate random access to the target cell on the random access resource to access the target cell.

[0291] Based on Scheme 3, the signal quality of the first terminal device can be improved. This is because, before step S701, the first terminal device accesses the first access network device through the first NCR, which indicates that the first terminal device may be located at the cell edge of the first cell. If the first terminal device cannot access the first cell through the first NCR, the signal quality after the first terminal device does not access the first cell through the first NCR is very poor. Therefore, a cell handover is performed for the first terminal device, so that the first terminal device can access a target cell with good signal quality, thereby improving the signal quality of the first terminal device.

[0292] Furthermore, in cell handover, based on the configuration of the measurement object in step S901, the first terminal device does not measure the SSB that can be transferred by the second NCR, and therefore does not select the SSB, i.e., does not access the network via the second NCR, thereby avoiding the case where the first terminal device is rejected by the access network device after accessing the network via the second NCR, thereby improving cell handover efficiency.

[0293] The above describes the initial access of a terminal device in an NCR scenario. The following describes the initial access procedure for NCR-MT.

[0294] Figure 10 shows another communication method according to this application. In the communication method, a related design is performed for the initial access of NCR-MT. See Figure 10. The method includes the following steps:

[0295] S1001: The first NCR-MT determines that the frequency band supported by the first NCR-Fwd is the first frequency band.

[0296] The first NCR-MT is the MT of the first NCR, and the first NCR-Fwd is the Fwd of the first NCR. The first NCR may be an NCR controlled by the first access network device.

[0297] Optionally, the frequency band supported by the first NCR-Fwd may alternatively be understood as the operating frequency band of the first NCR-Fwd, or the first NCR-Fwd being able to receive and transmit signals on the first frequency band.

[0298] S1002: A first NCR-MT performs initial access on a first frequency band.

[0299] Optionally, the first NCR-MT performing initial access on the first frequency band may include: the first NCR-MT searching for frequencies on the first frequency band or measuring SSB on the first frequency band.

[0300] Optionally, after measuring the SSB on the first frequency band, the first NCR-MT may select the SSB on the first frequency band and perform subsequent access procedures, such as acquiring PCI and MIB, acquiring SIB1, selecting a PLMN, and initiating random access. Please refer to the relevant description of the initial access procedure of the IAB-MT. The details will not be described again in this specification.

[0301] Optionally, after the first NCR-MT completes initial access, the method may further include: the first NCR-MT measures an SSB on the first frequency band. For example, the measurement may be used for cell reselection or cell handover. When the measurement is used for cell handover, the first NCR-MT may further send a measurement report to the first access network device. The measurement report may indicate an identifier of the SSB measured by the first NCR-MT on the first frequency band and a signal strength of the SSB measured by the first NCR-MT.

[0302] Based on this solution, when performing initial access, cell reselection or cell handover, the NCR-MT takes into account the capabilities of the NCR-Fwd and performs the initial access or measurement on the frequency band supported by the NCR-Fwd, so that the NCR-Fwd can operate normally after the NCR-MT subsequently accesses the network, avoiding the case where the cell accessed by the NCR-MT is on a frequency band not supported by the NCR-Fwd, and ensuring the normal operation of the NCR.

[0303] In addition to the method shown in Figure 10, this application also provides a communication method for designing initial access of NCR-MT in an NPN scenario, see Figure 11. The method includes the following steps:

[0304] S1101: A first access network device transmits system information of a first cell. Correspondingly, a first NCR-MT receives the system information of the first cell.

[0305] The system information includes NCR support information, CAG information corresponding to at least one PLMN supported by the first cell, and cell reservation information.

[0306] Optionally, the NCR support information indicates whether each PLMN supported by the first cell supports NCR-MT access, or indicates whether the first cell supports NCR-MT access. For example, the NCR support information may be information in an NCR-support information element.

[0307] Optionally, the CAG information corresponding to the at least one PLMN supported by the first cell may be a CAG identifier, etc. The system information may include CAG information corresponding to each PLMN supported by the first cell.

[0308] Optionally, the cell reservation information indicates whether the first cell is a reserved cell. For example, the cell reservation information may be carried in a cellReservedForOtherUse information element. If the first cell is a CAG-only cell, the information element may be set to true, indicating that the cell reservation information indicates that the first cell is a reserved cell. If the first cell is a CAG cell but not a CAG-only cell, the information element may be set to false, indicating that the cell reservation information indicates that the first cell is not a reserved cell.

[0309] Optionally, the system information may be SIB1.

[0310] S1102: The first NCR-MT ignores the CAG information and cell reservation information, and accesses the first cell when the NCR support information indicates that the first PLMN supports access of the NCR-MT.

[0311] The first PLMN is the PLMN selected by the first NCR-MT in the initial access procedure.

[0312] Optionally, the first NCR-MT ignoring the CAG information and the cell reservation information may include: The first NCR-MT ignores (or does not parse) information elements carrying CAG information (e.g., CAG information elements) and information elements carrying cell reservation information (e.g., cellReservedForOtherUse).

[0313] Optionally, after the first NCR-MT accesses the first cell, the communication method may further include the following steps:

[0314] S1103: The first NCR-MT sends a message a to the first access network device. Correspondingly, the first access network device receives the message a from the first NCR-MT.

[0315] The message a includes an NCR indication, which indicates that the sender of the message a is an NCR or an NCR-MT. For example, the message a may be an RRC setup complete message.

[0316] S1104: The first access network device sends a message b to a mobility management network element (an AMF network element is used as an example). Correspondingly, the AMF network element receives a message b from the first access network device.

[0317] Message b includes fifth information, which indicates that the terminal device associated with message b is NCR-MT.

[0318] Optionally, message b may be an initial UE message. In addition, message b may also be referred to as a fourth message.

[0319] S1105: The AMF network element determines, based on the fifth information, not to perform NPN access control for the terminal device. In other words, the AMF network element does not perform NPN access control for the first NCR-MT.

[0320] Optionally, the AMF network element not performing NPN access control for the first NCR-MT may include: the AMF network element not checking the allowed CAG list of the first NCR-MT.

[0321] S1106: The AMF network element sends a message c to the first access network device. Correspondingly, the first access network device receives a message c from the AMF network element.

[0322] The message c is used to request the first access network device to set up a first NCR-MT context, for example, the message c may be an INITIAL CONTEXT SETUP REQUEST message.

[0323] Based on this solution, the NCR-MT ignores CAG information and cell reservation information, so that non-NPN NCRs (i.e., NCRs that do not satisfy the NPN constraints) are allowed to access CAG-only cells, improving the coverage of non-NPN NCRs, reducing the production cost and complexity of NCRs, and facilitating large-scale deployment of NCRs.

[0324] Furthermore, because NCR-Fwd transparently amplifies and forwards only physical signals, ignoring NPN constraints by NCR-MT does not affect general terminal devices. Even when a non-NPN NCR accesses a CAG-only cell, the general terminal device in the CAG-only cell still determines the NPN constraints, and the AMF network element still performs NPN access control for the general terminal device. This prevents non-NPN UEs from accessing the CAG-only cell and does not cause extra energy consumption for the general terminal device.

[0325] It should be noted that the communication methods shown in Figures 10 and 11 may be performed separately or in combination. When the communication methods are performed in combination, for example, as shown in Figure 12, the initial access procedure of the first NCR-MT may include the following steps:

[0326] S1201: A first access network device transmits an SSB.

[0327] S1202: The first NCR-MT measures SSB on the first frequency band.

[0328] The first frequency band is a frequency band supported by the first NCR-Fwd. In this embodiment, an example in which the SSB transmitted by the first access network device is on the first frequency band is used for description.

[0329] After measuring the SSB on the first frequency band, the first NCR-MT may select the SSB on the first frequency band, obtain the PCI and MIB based on the SSB, know the time-frequency position of SIB1, and perform the following step S1203.

[0330] S1203: The first access network device sends SIB1. Correspondingly, the first NCR-MT receives SIB1.

[0331] The SIB1 may be an implementation of the system information of the first cell in step S1101. Specifically, the SIB1 includes NCR support information included in the system information, CAG information corresponding to at least one PLMN supported by the first cell, and cell reservation information. For details, please refer to the related description in step S1101. The details will not be described again in this specification.

[0332] S1204: The first NCR-MT ignores the CAG information and cell reservation information and determines that the first PLMN supports the access of the NCR-MT.

[0333] S1205: The first NCR-MT and the first access network device perform random access.

[0334] Steps S1206 to S1209 are the same as steps S1103 to S1106. For details, please refer to the relevant explanations in steps S1103 to S1106. The details will not be explained again in this specification.

[0335] Optionally, after step S1209, the first NCR-MT may measure SSB on the first frequency band, and the measurement may be used for cell reselection or cell handover.

[0336] In addition to the above method, this application further provides a communication method for realizing an access network device actively triggering the wake-up of an idle NCR-MT. As shown in Figure 13, the communication method includes the following steps:

[0337] S1301: A first access network device sends a first message to a mobility management network element. In response, the mobility management network element receives the first message from the first access network device.

[0338] In a first possible implementation, the first message is used to request a system temporary mobile subscriber identity (S-TMSI) of the first NCR-MT. For example, in a 5G system, the S-TMSI may be a 5G-S-TMSI. The first message may also be referred to as a current S-TMSI request message.

[0339] It can be understood that since the access network device does not recognize the S-TMSI of the terminal device, the first access network device needs to request the S-TMSI of the first NCR-MT from the mobility management network element.

[0340] In a second possible implementation manner, the first message is used to request the mobility management network element to retain the NGAP ID of the first NCR-MT.

[0341] For example, the first message may be used to request the mobility management network element to retain the NGAP ID of the first NCR-MT when the mobility management network element releases the context of the first NCR-MT. The first message may also be referred to as a retain NCR-MT's NGAP ID request message.

[0342] S1302: The first access network device sends a second message to the mobility management network element. In response, the mobility management network element receives the second message from the first access network device.

[0343] The first access network device may perform step S1302 when the first access network device needs to send control information to the first NCR-MT in an idle state. The second message is used to request the first NCR-MT in an idle state to start paging.

[0344] In a first possible implementation manner, when the first message is used to request the S-TMSI of the first NCR-MT, the second message includes the S-TMSI of the first NCR-MT.

[0345] In a second possible implementation manner, when the first message is used to request the mobility management network element to retain the NGAP ID of the first NCR-MT, the second message includes the NGAP ID of the first NCR-MT, for example, a RAN UE NGAP ID and / or an AMF UE NGAP ID.

[0346] S1303: The mobility management network element sends a paging message of the first NCR-MT.

[0347] The paging message includes the S-TMSI of the first NCR-MT. The paging message is used to wake up the first NCR-MT, causing the first NCR-MT to enter a connected state.

[0348] The method shown in Figure 13 is further described below. When the first message is used to request the S-TMSI of the first NCR-MT: Optionally, the first message may include a radio access network side NGAP ID (e.g., RAN UE NGAP ID) of the first NCR-MT and / or a mobility management network element side NGAP ID (e.g., AMF UE NGAP ID) of the first NCR-MT, where the NGAP ID is used to notify the mobility management network element of the S-TMSI of the terminal device required by the first access network device.

[0349] Optionally, as shown in FIG. 14, after step S1301, the communication method may further include the following steps S1304 to S1306.

[0350] S1304: The mobility management network element sends a third message to the first access network device. Correspondingly, the first access network device receives the third message from the mobility management network element.

[0351] The third message includes the S-TMSI of the first NCR-MT, for example, the third message includes a mapping relationship between the S-TMSI and the NGAP ID (RAN UE NGAP ID and / or AMF UE NGAP ID).

[0352] After receiving the third message, the first access network device stores the S-TMSI of the first NCR-MT. For example, the first access network device stores a mapping relationship between the RAN-side identifier of the first NCR-MT and the S-TMSI of the first NCR-MT. The RAN-side identifier of the first NCR-MT may be, for example, a cell-radio network temporary identifier (C-RNTI).

[0353] S1305: The first access network device sends an RRC release message to the first NCR-MT. Correspondingly, the first NCR-MT receives an RRC release message from the first access network device.

[0354] The RRC release message is used to release the first NCR-MT to an RRC idle state, and the first access network device releases the context of the first NCR-MT on the RAC side.

[0355] S1306: The first access network device and the mobility management network element perform a UE context release procedure, and the first NCR-MT context is released on the core network side.

[0356] For example, the first access network device sends a UE Context release request message to the mobility management network element. After receiving the UE context release request, the mobility management network element sends a UE Context release response message to the first access network device.

[0357] After step S1306, the first NCR-MT is in an RRC idle state. Thereafter, when the first access network device needs to send control information to the first NCR-MT in the idle state, the first access network device may perform step S1302 and send a second message to the mobility management network element.

[0358] Optionally, the first access network device stores a mapping relationship between the C-RNTI of the first NCR-MT and the S-TMSI of the first NCR-MT. Thus, when the first access network device needs to again transmit control information to the idle NCR-MT identified by the C-RNTI, the first access network device may send a second message to the mobility management network element, where the second message carries the S-TMSI corresponding to the C-RNTI.

[0359] Optionally, the second message does not carry the NGAP ID of the first NCR-MT because the NG interface context of the first NCR-MT has been released. The second message is used by the first access network device to request the mobility management network element to initiate paging for the first NCR-MT, but the second message is not associated with the UE (NCR-MT).

[0360] When the first message is used to request the mobility management network element to retain the NGAP ID of the first NCR-MT, Optionally, the first message may include a radio access network side NGAP ID (e.g., RAN UE NGAP ID) of the first NCR-MT and / or a mobility management network element side NGAP ID (e.g., AMF UE NGAP ID) of the first NCR-MT, where the NGAP ID is used to notify the mobility management network element of the NGAP ID of the terminal device that the first access network device requests the mobility management network element to retain.

[0361] Optionally, as shown in FIG. 15, after step S1301, the communication method may further include the following steps S1307 to S1309.

[0362] S1307: The first access network device and the mobility management network element respectively store the NGAP ID of the first NCR-MT.

[0363] For example, the first access network device stores a mapping relationship between the RAN-side identifier (e.g., C-RNTI) of the first NCR-MT and the NGAP ID. The mobility management network element stores a mapping relationship between the S-TMSI of the first NCR-MT and the NGAP ID. The NGAP ID includes a RAN UE NGAP ID and / or an AMF UE NGAP ID.

[0364] S1308 and S1309 are the same as S1305 and S1306. For details, please refer to the relevant descriptions in steps S1305 and S1306. The details will not be described again in this specification.

[0365] It can be understood that the context of the first NCR-MT is released, but the information stored in step S1307 is still retained.

[0366] After step S1309, the first NCR-MT is in an RRC idle state. Thereafter, when the first access network device needs to send control information to the first NCR-MT in the idle state, the first access network device may perform step S1302 and send a second message to the mobility management network element.

[0367] Optionally, the first access network device stores a mapping relationship between the C-RNTI of the first NCR-MT and the NGAP ID of the first NCR-MT. Thus, when the first access network device needs to again transmit control information to the idle NCR-MT identified by the C-RNTI, the first access network device may send a second message to the mobility management network element, where the second message carries the RAN UE NGAP ID and / or the AMF UE NGAP ID corresponding to the C-RNTI.

[0368] After receiving the second message, the mobility management network element may identify the terminal device (i.e., the first NCR-MT) to which the paging message needs to be sent based on the information stored in S1307, and perform step S1303.

[0369] Based on this solution, when the access network device releases the NCR-MT to the RRC idle state, the access network device requests the S-TMSI of the NCR-MT from the mobility management network element or requests the mobility management network element to store the NGAP ID of the NCR-MT, so that when the access network device needs to send control information to the NCR-MT again, the access network device may identify the NCR-MT by using the S-TMSI or NGAP ID, so that the mobility management network element can send a paging message to the NCR-MT and wake up the NCR-MT, allowing the NCR-MT to enter the RRC connected state.

[0370] In other words, based on the above solution, after releasing the NCR-MT to the RRC idle state, the access network device can wake up the NCR-MT again. NCR energy saving is realized without affecting the access network device's control over the NCR. This facilitates the normal operation of the NCR.

[0371] Additionally, the NCR operation, administration and maintenance (OAM) server may indicate that the NCR should be turned off. For example, due to reasons such as NCR maintenance, the OAM server may execute remote control to turn off the NCR. In this case, the NCR-Fwd is turned off. However, it is not yet specified how to handle the NCR-MT in this scenario.

[0372] Based on this, this application further provides a communication method. When NCR-Fwd is turned off, NCR-MT can enter an idle state. As shown in Figure 18, the communication method includes the following steps:

[0373] S1801: When a first condition is met, the first NCR-Fwd determines that the first NCR-MT needs to (or will) enter an idle state.

[0374] The idle state may be an RRC idle state, and the idle state and the RRC idle state may be replaced with each other.Furthermore, for example, the first condition may have the following two cases:

[0375] Case 1: The first condition may include: a first NCR-Fwd receives first indication information from a first OAM server;

[0376] The first instruction information indicates to turn off the first NCR, or the first instruction information instructs the first NCR-MT to enter an idle state. The first OAM server is an OAM server of the first NCR.

[0377] In other words, before step S1801, the communication method may further include the following step S1800.

[0378] S1800: The first OAM server sends first instruction information to the first NCR-Fwd. In response, the first NCR-Fwd receives the first instruction information from the first OAM server.

[0379] Optionally, the data plane protocol stacks of the OAM server and the NCR may be as shown in Figure 19. See Figure 19. The peer data plane protocol stack between the NCR-Fwd and the OAM server includes at least one of an OAM layer, a transmission control protocol (TCP) layer, and an IP layer. The peer data plane protocol stack between the NCR-MT and an access network device (e.g., gNB) includes at least one of an SDAP layer, a PDCP layer, an RLC layer, a MAC layer, and a PHY layer. The peer data plane protocol stack between a user plane function (UPF) network element and the OAM server includes an IP layer. The peer data plane protocol stack between the UPF network element and the access network device includes at least one of a general packet radio service tunneling protocol for the user plane (GTP-U) layer, a user datagram protocol (UDP) layer, and an IP layer.

[0380] Optionally, based on the protocol stack shown in Figure 19, the information sent by the first OAM server may be transferred by using the PDU session of the first NCR-MT, but the information is parsed in the first NCR-Fwd. Thus, the first NCR-Fwd may know the content of the first indication information and determine (or judge) whether the first NCR-MT needs to enter the idle state based on the first indication information.

[0381] In a possible implementation, the first instruction information may indicate that the first NCR is to be turned off. In this case, the first NCR-Fwd may determine that the first NCR-MT needs to enter an idle state. In other words, the first NCR-Fwd may obtain (or infer or determine) that the first NCR-MT needs to enter an idle state based on the NCR being turned off.

[0382] Optionally, the first instruction information indicating to turn off the first NCR may alternatively be understood as the first instruction information instructing the first NCR to disable (or stop) the service. The two descriptions may be interchangeable, which is not particularly limited in this application.

[0383] Optionally, after receiving the first instruction information, the first NCR-Fwd may further be turned off based on the instruction of the first instruction information, for example, powered off, which is not particularly limited in this application.

[0384] In another possible implementation, the first instruction information may instruct the first NCR-MT to enter the idle state. In other words, the first OAM server may alternatively control the first NCR-MT and explicitly instruct the first NCR-MT to enter the idle state.

[0385] Optionally, after receiving the first instruction information, the first NCR-Fwd may analyze the first instruction information to find that the first OAM server instructs the first NCR-MT to enter an idle state, and determine that the first NCR-MT needs to enter an idle state.

[0386] Case 2: The first condition may include the arrival of an off-time of the first NCR.

[0387] Optionally, the arrival of the off-time of the first NCR may alternatively be understood as the arrival of a time when the first NCR is not permitted to provide service (or operate), the end of the service time of the first NCR, the end of the operation time of the first NCR, etc. The descriptions may be interchangeable.

[0388] Optionally, before step S1801, the first OAM server may pre-configure the times during which the first NCR is or is not allowed to provide service. For example, the first NCR may be configured to be turned on for a certain period of time and turned off for the remaining period, or the first NCR may be configured to be turned on and off alternately in a cyclical manner, e.g., turned on for a period of time, turned off for the next period of time, then turned on, turned off after being on for a period of time, etc.

[0389] Optionally, based on the pre-configuration of the first OAM server, the first NCR-Fwd may determine the on-time and off-time of the first NCR-Fwd. When the off-time arrives, the first NCR-Fwd may determine that the first NCR-MT needs to enter an idle state. Further, the first NCR-Fwd is turned off.

[0390] After the first NCR-MT determines that it needs to enter the idle state, the first NCR-MT may perform the following step S1802.

[0391] S1802: The first NCR-MT sends a first message to the first access network device. In response, the first access network device receives the first message from the first NCR-MT.

[0392] The first message is used to request the release of the RRC connection of the first NCR-MT, or the first message is used to request the release of the first NCR-MT to an idle state.

[0393] Optionally, after the first NCR-MT determines that it needs to enter the idle state, the first NCR-Fwd may notify the first NCR-MT that it needs to enter the idle state. The first NCR-MT may send a first message to the first access network device based on the notification of the first NCR-Fwd.

[0394] S1803: Perform an RRC connection release procedure of the first NCR-MT.

[0395] Optionally, after receiving the first message, the first access network device may trigger an RRC connection release procedure of the first NCR-MT. After the RRC connection release procedure of the first NCR-MT is completed, the first NCR-MT enters an idle state. For the implementation manner of step S1803, please refer to the related description in step S2002 below. The details will not be described again in this specification.

[0396] Based on this solution, the NCR-Fwd may determine whether the NCR-MT needs to enter the idle state. When the NCR-MT needs to enter the idle state, the NCR-MT requests the access network device to release the NCR-MT's RRC connection and enters the idle state. This conforms to the currently defined principle that only the access network device can control the NCR-MT to enter the idle state, and is highly compatible. Furthermore, when the NCR is instructed to be turned off, the NCR-Fwd determines that the NCR-MT needs to enter the idle state. Because the NCR-MT may not need to control the NCR-Fwd after it is turned off, the NCR-MT enters the idle state in this scenario, achieving NCR energy savings.

[0397] In addition to the method shown in Figure 18, this application also provides another communication method. When NCR-Fwd is turned off, NCR-MT can enter idle state. As shown in Figure 20, the communication method includes the following steps:

[0398] S2001: A second OAM server sends a second message to a first access network device. In response, the first access network device receives the second message from the second OAM server.

[0399] The second message is used to notify (or request) the first access network device to release the RRC connection of the first NCR-MT, or the second message is used to notify (or request) the first access network device to release the first NCR-MT to an idle state. The second OAM server is an OAM server of the first access network device.

[0400] Optionally, the OAM server of the first access network device and the OAM server of the first NCR may be the same OAM server, i.e., the second OAM server is the same as the first OAM server. In this case, when controlling the first NCR to be turned off, the second OAM server may send a second message to the first access network device.

[0401] Alternatively, the OAM server of the first access network device and the OAM server of the first NCR may be different OAM servers, i.e., the second OAM server is different from the first OAM server. In this case, before step S2001, the method may further include the following step S2000.

[0402] S2000: The first OAM server sends message A to the second OAM server. In response, the second OAM server receives message A from the first OAM server.

[0403] Message A is used to request the second OAM server to notify the first access network device to release the RRC connection of the first NCR-MT, or message A is used to request the second OAM server to notify the first access network device to release the first NCR-MT to an idle state.

[0404] Optionally, message A includes an identifier of the first NCR, which may be, for example, a persistent identifier of the first NCR maintained by the first OAM server.

[0405] Optionally, after receiving message A, the second OAM server may perform step S2001 and send a second message to the first access network device. The second message may carry an identifier of the first NCR.

[0406] Optionally, the first OAM server may send message A to the second OAM server when the first NCR is instructed to be turned off or when the preconfigured off-time of the first NCR arrives. Furthermore, the first NCR-Fwd may be turned off when the first OAM server receives an off-instruction or when the off-time of the first NCR arrives. For details, please refer to the related description in the method shown in Figure 18. The details will not be described again in this specification.

[0407] S2002: Perform an RRC connection release procedure of the first NCR-MT.

[0408] Optionally, after receiving the second message, the first access network device may trigger an RRC connection release procedure of the first NCR-MT. After the RRC connection release procedure of the first NCR-MT is completed, the first NCR-MT enters an idle state.

[0409] For example, step S2002 may include: the first access network device sending a third message to the first NCR; and the first NCR correspondingly receiving a third message from the first access network device. The third message is used to release the RRC connection of the first NCR-MT, or the third message is used to release the first NCR-MT to an idle state. For example, the third message may be an RRC Release message.

[0410] Further, in step S2002, the first access network device may further interact with the mobility management network element to release the context of the first NCR-MT.

[0411] Based on this solution, the access network device may release the NCR-MT to the idle state based on the notification or request of the OAM server. This conforms to the currently defined principle that only the access network device can control the NCR-MT to enter the idle state, and has high compatibility. Furthermore, when it is determined that the NCR-Fwd is to be turned off, the OAM server may notify or request that the NCR-MT be released to the idle state. Since the NCR-MT may not need to control the NCR-Fwd after it is turned off, the NCR-MT is released to the idle state in this scenario, realizing NCR energy savings.

[0412] After the first NCR-MT is released to the idle state, there may be a requirement to wake up the first NCR-MT again to allow the first NCR-MT to enter a connected state (i.e., an RRC connected state). Based on this, this application further provides the following two implementation schemes for waking up an NCR-MT in an idle state:

[0413] Method 1: The first OAM server initiates paging to the first NCR-MT.

[0414] Optionally, the first OAM server may initiate paging to the first NCR-MT when the first NCR needs to be turned on again.

[0415] After receiving the paging message, the first NCR-MT may initiate random access and enter a connected state.

[0416] Optionally, the first NCR-Fwd that was turned off may be turned on after the first NCR-MT receives the paging message. Alternatively, the first OAM server may send information to the first NCR to indicate that the first NCR-Fwd that was turned off will be turned on again.

[0417] Method 2: The first NCR-MT in an idle state is woken up by using the communication method shown in Figure 21. See Figure 21. The communication method includes the following steps:

[0418] S2101: The second OAM server sends a fourth message to the first access network device. In response, the first access network device receives the fourth message from the second OAM server.

[0419] The fourth message is used to notify (or request) the first access network device to instruct the first NCR-MT to enter a connected state, or the fourth message is used to notify (or request) the first access network device to wake up the first NCR-MT that is in an idle state.

[0420] Optionally, the OAM server of the first access network device and the OAM server of the first NCR may be the same OAM server, i.e., the second OAM server is the same as the first OAM server. In this case, the second OAM server may perform step S2101 when the first NCR needs to be powered on again.

[0421] Alternatively, the OAM server of the first access network device and the OAM server of the first NCR may be different OAM servers, i.e., the second OAM server is different from the first OAM server. In this case, before step S2101, the method may further include the following step S2100.

[0422] S2100: The first OAM server sends message B to the second OAM server. In response, the second OAM server receives message B from the first OAM server.

[0423] Message B is used to request the second OAM server to notify the first access network device to instruct the first NCR-MT to enter a connected state, or message B is used to request the second OAM server to notify the first access network device to wake up the first NCR-MT that is in an idle state.

[0424] Optionally, message B includes an identifier of the first NCR, which may be, for example, a persistent identifier of the first NCR maintained by the first OAM server.

[0425] Optionally, after receiving message B, the second OAM server may perform step S2101 and send a fourth message to the first access network device. The fourth message may carry an identifier of the first NCR.

[0426] Optionally, when the first NCR needs to be powered on again, the first OAM server may send message B to the second OAM server.

[0427] S2102: The first access network device sends a broadcast message, and the first NCR-MT receives the broadcast message in response.

[0428] The broadcast message instructs the first NCR-MT to enter a connected state, or the broadcast message is used to wake up the first NCR-MT in an idle state. For example, the broadcast message may be a MIB or a SIB.

[0429] Optionally, the broadcast message may include an identifier of the first NCR (e.g., a persistent identifier of the first NCR maintained by the first OAM side). In addition, the broadcast message may further include second indication information, which instructs the first NCR-MT to enter a connected state. For example, the second indication information may be a 1-bit indicator.

[0430] After step S2102, after receiving the broadcast message, the first NCR-MT may initiate random access and enter a connected state.

[0431] Optionally, the first NCR-Fwd that was turned off may be turned on after the first NCR-MT receives the broadcast message. Alternatively, the first OAM server may send information to the first NCR to indicate that the first NCR-Fwd that was turned off will be turned on again.

[0432] According to Scheme 1 or Scheme 2, after the NCR-MT enters the idle state, the OAM server may initiate paging to the NCR-MT to wake it up, or the access network device may send a broadcast message to instruct the NCR-MT to enter the connected state. In other words, after the NCR-MT is released to the RRC idle state, the NCR-MT can wake up again. NCR energy saving is realized without affecting the access network device's control over the NCR. This facilitates the normal operation of the NCR.

[0433] It should be noted that Method 1 or Method 2 may be combined with the method shown in FIG. 18 or FIG. 20. For example, Method 1 or Method 2 may be used to enable an NCR-MT to enter a connected state from an idle state after the NCR-MT is released to the idle state by using the method shown in FIG. 18 or FIG. 20. Alternatively, Method 1 or Method 2 may be applied to waking up an NCR-MT in an idle state in other scenarios. The use scenarios of Method 1 or Method 2 are not particularly limited in this application. The above mainly describes the solution provided in this application. Correspondingly, this application also provides a communication device. The communication device may be configured to implement the above method or may implement the functions of a first terminal device, a first access network device, a first NCR, or a mobility management network element. The communication device may be the first terminal device in the above method embodiment, or may be a component that can be used in the first terminal device, for example, a chip or a chip system; the communication device may be the first access network device in the above method embodiment, or may be a component that can be used in the first access network device, for example, a chip or a chip system; the communication device may be the first NCR in the above method embodiment, or may be a component that can be used in the first NCR; or the communication device may be a mobility management network element in the above method embodiment, or may be a component that can be used in the mobility management network element.

[0434] It can be understood that to realize the above functions, the communication device includes a hardware structure and / or a software module for performing the corresponding functions. Those skilled in the art should easily recognize that, in combination with the example units and algorithm steps described in the embodiments disclosed in this specification, this application may be realized by hardware or a combination of hardware and computer software. Whether the functions are performed by hardware or by hardware driven by computer software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to realize the described functions for each specific application, but the implementation method should not be considered to go beyond the scope of this application.

[0435] In the embodiments of this application, the communication device may be divided into functional modules based on the above method embodiments. For example, each functional module may be obtained through division based on its corresponding function, or two or more functions may be integrated into one processing module. The integrated module may be implemented in the form of hardware or in the form of a software functional module. It should be noted that in the embodiments of this application, the module division is an example and is merely a logical functional division. In actual implementation, other division methods may be used.

[0436] 16 is a diagram of the structure of a communication device 160. The communication device 160 includes a processing module 1601 and a transceiver module 1602. The communication device 160 may be configured to implement the functions of a first terminal device, a first access network device, a first NCR, or a mobility management network element.

[0437] In some embodiments, communication device 160 may further include a storage module (not shown in FIG. 16) configured to store program instructions and data.

[0438] In some embodiments, the transceiver module 1602 may also be referred to as a transceiver unit and may be configured to perform transmission and / or reception functions. The transceiver module 1602 may include a transceiver circuit, a transceiver machine, a transceiver, or a communication interface.

[0439] In some embodiments, the transceiver module 1602 may include a receiving module and a transmitting module, respectively, configured to perform the receiving and transmitting steps performed by the first terminal device, the first access network device, the first NCR, or the mobility management network element in the above method embodiments and / or configured to support other processes of the techniques described herein. The processing module 1601 may be configured to perform the processing (e.g., determining) steps performed by the first terminal device, the first access network device, the first NCR, or the mobility management network element in the above method embodiments and / or configured to support other processes of the techniques described herein.

[0440] When the communication device 160 is configured to implement the functionality of a first terminal device, The transceiver module 1602 is configured to receive system information of a first cell, the system information including indication information indicating a public land mobile network (PLMN) corresponding to a first synchronization signal and a physical broadcast channel block (SSB) of the first cell, and the processing module 1601 is configured to determine a PLMN corresponding to the first SSB based on the indication information.

[0441] Optionally, if the PLMN corresponding to the first SSB includes the first PLMN, the first SSB supports a terminal device that selects the first PLMN when performing initial access.

[0442] Optionally, if the PLMNs corresponding to the first SSB do not include the first PLMN, the first SSB does not support a terminal device selecting the first PLMN when performing initial access.

[0443] Optionally, when the first SSB is an SSB selected by the first terminal device in the initial access procedure, if the PLMN corresponding to the first SSB does not include the first PLMN, the processing module 1601 is configured to select a fifth SSB of the first cell and perform initial access based on the fifth SSB, where the first PLMN is the PLMN selected by the first terminal device in the initial access procedure.

[0444] Optionally, the indication information further indicates a PLMN corresponding to the fifth SSB, where the PLMN corresponding to the fifth SSB includes the first PLMN.

[0445] When the communication device 160 is configured to implement the functionality of a first access network device, In some embodiments, The processing module 1601 is configured to determine indication information, the indication information indicating a public land mobile network (PLMN) corresponding to a first synchronization signal and a physical broadcast channel block (SSB) of the first cell. The transceiver module 162 is configured to transmit system information of the first cell, the system information including the indication information.

[0446] Optionally, if the PLMN corresponding to the first SSB includes the first PLMN, the first SSB supports a terminal device that selects the first PLMN when performing initial access.

[0447] Optionally, if the PLMNs corresponding to the first SSB do not include the first PLMN, the first SSB does not support a terminal device selecting the first PLMN when performing initial access.

[0448] In other embodiments, The transceiver module 1602 is configured to receive first information via a first NCR, the first information indicating a first public land mobile network (PLMN), the first PLMN being a PLMN selected by the first terminal device in the initial access procedure. The processing module 161 is configured to deny access of the first terminal device via the first NCR if the first NCR does not support the first PLMN.

[0449] Optionally, the transceiver module 1602 is further configured to receive second information, the second information indicating at least one PLMN supported by the first NCR.

[0450] Optionally, if the PLMN selected by the first NCR in the initial access procedure is different from the first PLMN, the first NCR does not support the first PLMN.

[0451] Optionally, if the first PLMN does not support access of the network controlled repeater mobile terminal NCR-MT, the first NCR does not support the first PLMN.

[0452] Optionally, the transceiver module 1602 is further configured to transmit system information, where the system information indicates whether the first cell supports NCR-MT access.

[0453] Optionally, the transceiver module 1602 is configured to transmit system information, where the system information indicates whether each PLMN supported by the first cell supports NCR-MT access.

[0454] Optionally, the processing module 1601 being configured to deny access of the first terminal device via the first NCR includes: the processing module 1601 being configured to perform beam switching for the first terminal device.

[0455] Optionally, the processing module 1601 being configured to deny access of the first terminal device via the first NCR includes: the processing module being configured to send a radio resource control (RRC) message to the first terminal device through the transceiver module 1602, where the RRC message is used to release an RRC connection between the first terminal device and the first access network device.

[0456] Optionally, the RRC message includes third information, where the third information indicates a second SSB, where the second SSB is used for the next access of the first terminal device, and the SSBs that can be transferred by the first NCR do not include the second SSB, or the third information indicates a third SSB, where the third SSB is not used for the next access of the first terminal device, and the third SSB is an SSB that can be transferred by the first NCR.

[0457] Optionally, the processing module 1601 being configured to deny access of the first terminal device via the first NCR includes: the processing module 1601 being configured to perform a cell handover for the first terminal device.

[0458] Optionally, the processing module 1601 being configured to perform a cell handover to the first terminal device includes: the processing module 1601 being configured to send measurement configuration information to the first terminal device, where an SSB that can be forwarded by the second NCR does not exist in a measurement object indicated by the measurement configuration information, and the PLMNs served by the second NCR do not include the first PLMN.

[0459] Optionally, the second NCR comprises an NCR controlled by a second access network device.

[0460] Optionally, the transceiver module 1602 is further configured to receive fourth information, the fourth information indicating SSBs that can be forwarded by at least one NCR controlled by the second access network device and / or PLMNs served by the at least one NCR.

[0461] In yet some other embodiments, The transceiver module 1602 is configured to send a first message to the mobility management network element, where the first message is used to request a system temporary mobile subscriber identity (S-TMSI) of the first network controlled repeater mobile terminal (NCR-MT), or the first message is used to request the mobility management network element to retain an NG interface application protocol identity (NGAP ID) of the first NCR-MT. When the first access network device needs to send control information to the idle first NCR-MT, the transceiver module 1602 is further configured to send a second message to the mobility management network element, where the second message is used to request initiating paging for the idle first NCR-MT, and the second message includes the S-TMSI of the first NCR-MT, or the second message includes the NGAP ID of the first NCR-MT.

[0462] Optionally, the first message includes a radio access network side NGAP ID of the first NCR-MT and / or a mobility management network element side NGAP ID of the first NCR-MT.

[0463] Optionally, the first message is used to request an S-TMSI of the first NCR-MT. The transceiver module 1602 is further configured to receive a third message from the mobility management network element, the third message including the S-TMSI of the first NCR-MT. The processing module 1601 is configured to store the S-TMSI of the first NCR-MT.

[0464] Optionally, the first message is used to request the mobility management network element to retain the NGAP identification information of the first NCR-MT. The processing module 1601 is further configured to store, by the first access network device, the NGAP ID of the first NCR-MT.

[0465] In yet some other embodiments, The transceiver module 1602 is configured to receive a second message from the second OAM server, the second message being used to notify the first access network device to release a radio resource control (RRC) connection of the first NCR-MT. The transceiver module 1602 is further configured to send a third message to the first NCR, the third message being used to release the RRC connection of the first NCR-MT.

[0466] In yet some other embodiments, The transceiver module 1602 is configured to receive a fourth message from the second Operation, Administration and Maintenance OAM Server, where the fourth message is used to notify the first access network device to instruct the first NCR-MT to enter a connected state. The transceiver module 1602 is further configured to send a broadcast message, where the broadcast message instructs the first NCR-MT to enter a connected state.

[0467] When the communication device 160 is configured to implement the functionality of the first NCR, In some embodiments, The processing module 1601 is configured to determine second information, the second information indicating at least one public land mobile network (PLMN) supported by a first NCR, the first NCR being an NCR controlled by the first access network device. The transceiver module 1602 is further configured to transmit the second information to the first access network device.

[0468] In some other embodiments, The processing module 1601 is configured to determine, by a first network controlled repeater mobile terminal NCR-MT, that a frequency band supported by a first network controlled repeater forwarding module NCR-Fwd is a first frequency band. The transceiver module 1602 is configured, by the first NCR-MT, to perform initial access on the first frequency band.

[0469] Optionally, after the first NCR-MT completes initial access, the processing module 1601 is further configured to measure a synchronization signal and a physical broadcast channel block SSB on the first frequency band by the first NCR-MT.

[0470] In yet some other embodiments, The transceiver module 1602 is configured to receive, by a first network controlled repeater mobile terminal (NCR-MT), system information of a first cell, the system information including NCR support information, closed access group (CAG) information corresponding to at least one public land mobile network (PLMN) supported by the first cell, and cell reservation information, where the NCR support information indicates whether each PLMN supported by the first cell supports access for the NCR-MT, and the cell reservation information indicates whether the first cell is a reserved cell.

[0471] The processing module 1601 is configured, by the first NCR-MT, to ignore the CAG information and the cell reservation information and access the first cell when the NCR support information indicates that the first PLMN supports access of the NCR-MT, where the first PLMN is the PLMN selected by the first NCR-MT in the initial access procedure.

[0472] In yet some other embodiments, The processing module 1601 is configured to determine, by the first NCR-Fwd, that the first NCR-MT needs to enter an idle state when a first condition is met. The transceiver module 1602 is configured, by the first NCR-MT, to send a first message to the first access network device, the first message being used to request the release of the radio resource control connection (RRC) of the first NCR-MT. The first condition includes: the first NCR-Fwd receiving first instruction information from the first operation, administration and maintenance server, the first instruction information indicating turning off the first NCR or instructing the first NCR-MT to enter an idle state. Alternatively, the first condition includes the arrival of the turn-off time of the first NCR.

[0473] When the communication device 160 is configured to implement the functionality of a mobility management network element, The transceiver module 1602 is configured to receive a fourth message from the first access network device, the fourth message including fifth information, the fifth information indicating that the terminal device associated with the fourth message is a network controlled repeater mobile terminal NCR-MT. The processing module 1601 is configured to determine, based on the fifth information, not to perform non-public network NPN access control on the terminal device.

[0474] All relevant contents of the steps in the above method embodiments may be cited in the functional descriptions of the corresponding functional modules, and the details will not be described again in this specification.

[0475] Optionally, in this application, the processing module receiving / transmitting information through the transceiver module may alternatively be understood as the processing module controlling the transceiver module to receive / transmit information, the processing module transmitting information through the transceiver module may alternatively be understood as the processing module outputting information to the transceiver module and the transceiver module transmitting the information, and the processing module receiving information through the transceiver module may alternatively be understood as the transceiver module receiving information and inputting the information to the processing module.

[0476] In this application, communication device 160 may be presented in the form of functional modules obtained through division in an integrated manner. A "module" herein may be an application-specific integrated circuit (ASIC), circuitry, a processor executing one or more software or firmware programs, memory, integrated logic circuitry, and / or other components capable of providing the functionality described above.

[0477] In some embodiments, when the communication device 160 in FIG. 16 is a chip or a chip system, the functions / implementation processes of the transceiver module 1602 may be realized through an input / output interface (or communication interface) of the chip or chip system, and the functions / implementation processes of the processing module 1601 may be realized by a processor (or processing circuit) of the chip or chip system.

[0478] The communication device 160 provided in this embodiment may implement the above method. Therefore, the technical effects that can be achieved by the communication device refer to the above method embodiment. The details will not be described again in this specification.

[0479] In possible product forms, the first terminal device, first access network device, first NCR or mobility management network element in the embodiments of this application may alternatively be realized by one or more field programmable gate arrays (FPGAs), programmable logic devices (PLDs), controllers, state machines, gate logic, discrete hardware components, any other suitable circuitry, or any combination of circuitry capable of performing the various functions described throughout this application.

[0480] In other possible product forms, the first terminal device, the first access network device, the first NCR or the mobility management network element in this application may use the configuration structure or include the components shown in Figure 17. Figure 17 is a diagram of the configuration of a communication device 1700 according to this application.

[0481] 17, the communication device 1700 includes at least one processor 1701. Optionally, the communication device further includes a communication interface 1702.

[0482] The device 1700 may be capable of implementing the communication method provided in any one of the above embodiments and any possible designs thereof when the associated program instructions are executed in the at least one processor 1701. Alternatively, the processor 1701 is configured to implement the communication method provided in any one of the above embodiments and any possible designs thereof using logic circuits or by executing code instructions.

[0483] Communications interface 1702 may be configured to receive program instructions and transmit program instructions to the processor. Alternatively, communications interface 1702 may be configured to perform communications interactions between communications apparatus 1700 and other communications devices, e.g., to exchange control signaling and / or service data. For example, communications interface 1702 may be configured to receive signals from apparatuses other than apparatus 1700 and transmit the signals to processor 1701, or to transmit signals from processor 1701 to communications apparatuses other than apparatus 1700.

[0484] Optionally, the communication interface 1702 may be a code and / or data read / write interface circuit, or the communication interface 1702 may be a signal transmission interface circuit between a communication processor and a transceiver, or may be a pin on a chip.

[0485] Optionally, the communication device 1700 may further include at least one memory 1703, which may be configured to store required related program instructions and / or data. It should be noted that the memory 1703 may be independent of the processor 1701 or may be integrated with the processor 1701. The memory 1703 may be located inside the communication device 1700 or may be located outside the communication device 1700. This is not a limitation.

[0486] Optionally, communication device 1700 may further include a power supply circuit 1704, which may be configured to provide power to processor 1701. Power supply circuit 1704 may be located on the same chip as processor 1701 or may be located on a chip other than the chip on which processor 1701 is located.

[0487] Optionally, the communications device 1700 may further include a bus 1705 , and portions of the communications device 1700 may be interconnected through the bus 1705 .

[0488] Optionally, in this application, a processor may be a central processing unit (CPU), or the processor may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor, or the processor may be any conventional processor, etc.

[0489] Optionally, in this application, memory may be volatile memory or nonvolatile memory, or may include volatile and nonvolatile memory. Nonvolatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory may be random access memory (RAM) used as an external cache. By way of example and not limitation, many forms of random access memory (RAM) are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchlink dynamic random access memory (SLDRAM), or direct rambus random access memory (DR RAM).

[0490] Optionally, in an embodiment of this application, the power supply circuit includes, but is not limited to, at least one of the following: a power supply line, a power supply subsystem, a power management chip, a power consumption management processor, or a power consumption management control circuit.

[0491] In some embodiments, in a hardware implementation, those skilled in the art will appreciate that the communications device 160 shown in FIG. 16 may take the form of communications device 1700 shown in FIG.

[0492] In one example, the functions / implementation processes of the processing module 1601 in FIG. 16 may be implemented by a processor 1701 in a communication device 1700 shown in FIG. 17 by invoking computer-executable instructions stored in a memory 1703. The functions / implementation processes of the transceiver module 1602 in FIG. 16 may be implemented by a communication interface 1702 in the communication device 1700 shown in FIG. 17.

[0493] It should be noted that the structure shown in Figure 17 does not constitute a specific limitation on the first terminal device, the first access network device, the first NCR, or the mobility management network element. For example, in some other embodiments of this application, the first terminal device, the first access network device, the first NCR, or the mobility management network element may include more or fewer components than those shown in the figures, or may combine some components, split some components, or have a different component arrangement. The components shown in the figures may be realized by hardware, software, or a combination of software and hardware.

[0494] In some embodiments, the embodiments of the present application further provide a communication device, the communication device including a processor configured to implement the method in any one of the above method embodiments.

[0495] In a possible implementation, the communication device further includes a memory. The memory is configured to store necessary computer programs and data. The computer programs may include instructions. The processor may call the instructions in the computer programs stored in the memory to instruct the communication device to perform the method in any one of the above method embodiments. Obviously, the communication device may not include a memory.

[0496] In another possible implementation, the communication device further includes an interface circuit, which is a code / data read / write interface circuit configured to receive computer-executable instructions (which may be stored in a memory and read directly from the memory or read through other components) and transmit the computer-executable instructions to the processor.

[0497] In another possible implementation, the communication device may further include a communication interface, which may be configured to communicate with a module external to the communication device.

[0498] It can be understood that the communication device may be a chip or a chip system. When the communication device is a chip system, the communication device may include a chip, or may include a chip and other discrete components. This is not particularly limited in the embodiments of this application.

[0499] This application further provides a computer-readable storage medium, which stores a computer program or instruction, and when the computer program or instruction is executed by a computer, the functions of any one of the above method embodiments are realized.

[0500] This application further provides a computer program product, which, when executed by a computer, realizes the functions of any one of the above method embodiments.

[0501] Those skilled in the art may understand that for the purpose of convenient and concise description, the detailed operation processes of the above systems, devices and units may be referred to the corresponding processes in the above method embodiments, and the details will not be described again in this specification.

[0502] It can be understood that the systems, devices, and methods described in this application may alternatively be implemented in other ways. For example, the described device embodiments are merely examples. For example, the division into units is merely a logical division of function. Other division schemes may exist in actual implementations. For example, multiple units or components may be combined or integrated into other systems, or some features may be ignored or not implemented. Furthermore, the shown or discussed mutual couplings or direct couplings or communication connections may be realized through some interfaces. Indirect couplings or communication connections between devices or units may be realized in electronic, mechanical, or other forms.

[0503] The units described as separate parts may or may not be physically separated, i.e., may be co-located or may be distributed across multiple network units. The parts shown as units may or may not be physical units. Some or all of the units may be selected based on actual requirements to achieve the objectives of the solutions of the embodiments.

[0504] Furthermore, the functional units in the embodiments of this application may be integrated into one processing unit, each of the units may exist physically alone, or two or more units may be integrated into one unit.

[0505] All or part of the above embodiments may be realized by using software, hardware, firmware, or any combination thereof. When a software program is used to realize the embodiments, the embodiments may be fully or partially realized in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the procedures or functions according to the embodiments of this application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from a computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website, computer, server, or data center to another website, computer, server, or data center via a wired (e.g., coaxial cable, optical fiber, or digital subscriber line (DSL)) or wireless (e.g., infrared, radio, or microwave) method. The computer-readable storage medium may be any available medium accessible by a computer, or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, or a magnetic tape), an optical medium (e.g., a DVD), a semiconductor medium (e.g., a solid-state disk (SSD)), etc. In an embodiment of this application, a computer may include the above-mentioned devices.

[0506] Although this application has been described with reference to embodiments, in the process of realizing this application for which protection is claimed, those skilled in the art may understand and realize other variations of the disclosed embodiments by studying the accompanying drawings, the disclosed content, and the appended claims. In the claims, "comprising" does not exclude other components or steps, and "a" or "one" does not exclude a plurality. A single processor or other unit may fulfill several functions recited in the claims. Although certain measures are recited in mutually different dependent claims, this does not mean that these measures cannot be combined to produce better effects.

[0507] Although this application has been described with reference to its specific features and embodiments, it is clear that various modifications and combinations may be made thereto without departing from the scope of protection of this application. Correspondingly, the specification and the accompanying drawings are merely exemplary descriptions of this application as defined by the appended claims, and any or all of the modifications, variations, combinations or equivalents encompassing the scope of this application are considered. It is clear that a person skilled in the art can make various modifications and variations to this application without departing from the scope of this application. Thus, this application intends to cover these modifications and variations of this application, provided that they fall within the scope of the claims of this application and their equivalent technologies.

Claims

1. 1. A communication method comprising: receiving system information of a first cell, the system information including indication information, the indication information indicating a public land mobile network (PLMN) corresponding to a first synchronization signal and a physical broadcast channel block (SSB) of the first cell; determining the PLMN corresponding to the first SSB based on the indication information; A method comprising:

2. 2. The method of claim 1, wherein, if the PLMN corresponding to the first SSB includes a first PLMN, the first SSB supports a terminal device that selects the first PLMN when performing initial access.

3. 3. The method according to claim 1, wherein if the PLMNs corresponding to the first SSB do not include the first PLMN, the first SSB does not support a terminal device that selects the first PLMN when performing initial access.

4. The first SSB is an SSB selected by the first terminal device in an initial access procedure, and the method includes: When the PLMN corresponding to the first SSB does not include the first PLMN, selecting a fifth SSB of the first cell and performing initial access based on the fifth SSB; or performing initial access based on the first SSB when the PLMN corresponding to the first SSB includes a first PLMN; Further comprising: The method of claim 1 , wherein the first PLMN is a PLMN selected by the first terminal device in the initial access procedure.

5. The method of claim 4 , wherein the indication information further indicates a PLMN corresponding to the fifth SSB, and the PLMN corresponding to the fifth SSB includes the first PLMN.

6. The method according to claim 1 , wherein the indication information includes an identifier of the first SSB and an identification of the PLMN corresponding to the first SSB.

7. 1. A communication method comprising: determining indication information, the indication information indicating a public land mobile network (PLMN) corresponding to a first synchronization signal and a physical broadcast channel block (SSB) of a first cell; transmitting system information of the first cell, the system information including the indication information; A method comprising:

8. 8. The method of claim 7, wherein, if the PLMN corresponding to the first SSB includes a first PLMN, the first SSB supports a terminal device that selects the first PLMN when performing initial access.

9. 9. The method according to claim 7, wherein if the PLMNs corresponding to the first SSB do not include the first PLMN, the first SSB does not support a terminal device that selects the first PLMN when performing initial access.

10. The method according to claim 7 , wherein the indication information includes an identifier of the first SSB and an identification of the PLMN corresponding to the first SSB.

11. A network controlled repeater (NCR) based communication method, comprising: receiving first information via a first NCR, the first information indicating a first public land mobile network (PLMN), the first PLMN being a PLMN selected by a first terminal device in an initial access procedure; denying access of the first terminal device via the first NCR if the first NCR does not support the first PLMN; A method comprising:

12. 12. The method of claim 11, further comprising: receiving second information, the second information indicating at least one PLMN supported by the first NCR.

13. 12. The method of claim 11, wherein if a PLMN selected by the first NCR in the initial access procedure is different from the first PLMN, the first NCR does not support the first PLMN.

14. 12. The method of claim 11, wherein the first NCR does not support the first PLMN if the first PLMN does not support access of a network controlled repeater mobile terminal (NCR-MT).

15. Before receiving the first information via the first NCR, the method includes:

14. The method of claim 11, further comprising: transmitting system information, the system information indicating whether the first cell supports NCR-MT access.

16. Before receiving the first information via the first NCR, the method includes:

15. The method of claim 11, further comprising: transmitting system information, the system information indicating whether each PLMN supported by the first cell supports NCR-MT access.

17. The step of denying the access of the first terminal device via the first NCR includes:

17. The method according to any one of claims 11 to 16, comprising the step of performing beam switching for the first terminal device.

18. The step of denying the access of the first terminal device via the first NCR includes:

17. The method of claim 11, comprising the step of transmitting a radio resource control (RRC) message to the first terminal device, the RRC message being used to release an RRC connection between the first terminal device and a first access network device.

19. the RRC message includes third information; The third information indicates a second SSB, and the second SSB is used for the next access of the first terminal device, and the SSBs that can be transferred by the first NCR do not include the second SSB, or 19. The method of claim 18, wherein the third information indicates a third SSB, the third SSB will not be used for a next access of the first terminal device, and the third SSB is an SSB that can be transferred by the first NCR.

20. The step of denying the access of the first terminal device via the first NCR includes:

17. The method of any one of claims 11 to 16, comprising the step of performing a cell handover for the first terminal device.

21. The step of performing a cell handover for the first terminal device includes:

21. The method of claim 20, comprising: transmitting measurement configuration information to the first terminal device, wherein an SSB that can be forwarded by a second NCR is not present in a measurement object indicated by the measurement configuration information, and PLMNs served by the second NCR do not include the first PLMN.

22. 22. The method of claim 21, wherein the second NCR comprises an NCR controlled by a second access network device.

23. 23. The method of claim 22, further comprising: receiving fourth information, the fourth information indicating SSBs that can be forwarded by at least one NCR controlled by the second access network device and / or PLMNs served by the at least one NCR.

24. A network controlled repeater (NCR) based communication method, comprising: determining second information, the second information indicating at least one public land mobile network (PLMN) supported by a first NCR, the first NCR being an NCR controlled by a first access network device; transmitting the second information to the first access network device; A method comprising:

25. A communication device, A communication device comprising a module configured to implement a method according to any one of claims 1 to 24.

26. 1. A communication device including at least one processor and a communication interface, 25. A communications device, wherein the communications interface is configured to receive and / or transmit signals and the processor is configured to enable a method according to any one of claims 1 to 24 to be performed.

27. 1. A computer-readable storage medium, comprising:

25. A computer readable storage medium storing computer program instructions which, when executed by a processor, implement the method of any one of claims 1 to 24.

28. 1. A computer program product comprising: The computer program product comprises program instructions which, when executed by a processor, cause the method of any one of claims 1 to 24 to be implemented.

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