Communication method and communication device

Abstract

The present application provides a communication method and a communication device. The method includes, after successfully performing a first random access in a radio resource control (RRC) inactive state, a terminal device receives downlink control information (DCI) transmitted by an access network device using a first receiving beam, where the first receiving beam is the same as the receiving beam of the downlink transmission of the first random access. In the method described in the present application, the terminal device receives the DCI in an RRC inactive state using a previously transmitted beam. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the receiving beam of the DCI, thereby reducing the power consumption of the terminal device.

Description

[Technical field]

[0001] The present application relates to the field of communication technologies, and in particular to communication methods and devices. [Background technology]

[0002] The radio resource control inactive (RRC inactive) state is a state that is used by the fifth generation th This is an RRC state of the 5G (5G) mobile communication technology. The purpose of the radio resource control inactive state is to allow the terminal device to quickly recover a dedicated connection and enter the RRC connected state without first accessing it. In RRC inactive, the terminal device may move within the radio access network based notification area (RNA) but not inform the access network device. The terminal device stores the terminal device's context and the previously served access network device stores the terminal device's context and the next generation (NG) connection for the access and mobility management function (AMF) and the user plane function (UPF). The dedicated RRC connection between the terminal device and the access network device may be suspended and then restored.

[0003] The signaling procedure for switching from the RRC idle state to the RRC connected state is actually the first access process of the terminal device, including random access, RRC connection setup, initial context setup, RRC reconfiguration process, security mode setup process, context setup process, authentication procedure, etc. By comparing this signaling procedure with the signaling procedure from the RRC inactive state to the RRC connected state, it can be found that in the RRC inactive state, many signaling exchanges can be reduced by the RRC resume procedure (for example, in the Uu interface, the RRC reconfiguration process and the security mode setup process are reduced, and in the NG interface, the context setup process and the authentication procedure are reduced, etc.). Since the signaling exchanges are reduced, the switch from the RRC inactive state to the RRC connected state is faster than the switch from the RRC idle state to the RRC connected state, thereby reducing the access delay.

[0004] Beam management is used to establish and maintain a group of appropriate beam sets. That is, in order to form a group of beam sets and maintain an excellent wireless connection, an appropriate transmit beam is selected at the transmitter and an appropriate receive beam is selected at the receiver. This process is called serving beam selection. Serving beam selection needs to be completed based on beam measurements of reference signals. In some scenarios, the initially established beam set may be blocked due to environmental changes, and there may not be enough time for the access network device and the terminal device to perform beam adjustment. In this case, another group of beam sets may be quickly selected and established through beam failure recovery.

[0005] Serving beam selection is to select and maintain a group of optimal beam pairs between a base station and a UE through a set of procedures including beam scanning, beam measurement and reporting, and beam indication, and to transmit uplink and downlink signals. As the terminal device moves within the network, the position and channel state of the terminal device may change, and the corresponding optimal beam pair also changes. Therefore, after the first serving beam is established, the serving beam is continuously adjusted to ensure that the optimal beam pair for uplink and downlink signal transmission is always used.

[0006] In the current version of the 5G protocol, beam management and beam failure recovery can only be set in the RRC connected state. Beam management and beam failure recovery are not supported in the RRC inactive state. In other words, the terminal device can perform beam management and beam failure recovery only when it is in the RRC connected state. According to the current standard, data transmission can be performed in the RRC inactive state without entering the RRC connected state. Considering this, the greatest advantage of the RRC inactive state is to save the energy and power of the terminal device. If beam management and beam failure recovery are supported in the RRC inactive state, the energy saving of the terminal device is not preferable.

Summary of the Invention

[0007] This application provides a communication method and a communication device that promote reducing the power consumption of a terminal device when data transmission is performed in the RRC inactive state.

Means for Solving the Problems

[0008] According to the first aspect, the present application provides a communication method. The method includes that after successfully performing a first random access in the radio resource control inactive (RRC inactive) state, the terminal device receives downlink control information (DCI) transmitted by the access network device using a first receiving beam, where the first receiving beam is the same as the receiving beam for the downlink transmission of the first random access.

[0009] In the method described in the first aspect, the terminal device performs the current transmission in the RRC inactive state using the beam previously transmitted. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam, thereby reducing the power consumption of the terminal device.

[0010] In a possible implementation example, the DCI indicates a downlink transmission resource or an uplink transmission resource. The terminal device may further perform downlink transmission through the downlink transmission resource, or may further perform uplink transmission through the uplink transmission resource using a first transmission beam. The receiving beam for the downlink transmission is the same as the first receiving beam. The first transmission beam is the same as the transmission beam for the uplink transmission of the first random access.

[0011] In this possible implementation example, the terminal device performs the current transmission in the RRC inactive state using the beam previously transmitted. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam, thereby reducing the power consumption of the terminal device.

[0012] In a possible implementation example, the first random access is a four-step random access, and the first receiving beam is the same as the receiving beam for message 2 or message 4 of the first random access.

[0013] In a possible implementation example, the first random access is a two-step random access, and the first receiving beam is the same as the receiving beam for message B of the first random access.

[0014] In a possible implementation example, the first random access is a 4-step random access, and the first transmission beam is the same as the transmission beam of message 1 or message 3 of the first random access.

[0015] In a possible implementation example, the first random access is a 2-step random access, and the first transmission beam is the same as the transmission beam of message A of the first random access.

[0016] In a possible implementation example, the terminal device may further receive indication information sent by the access network device. When the indication information indicates monitoring the physical downlink control channel PDCCH corresponding to the cell radio network temporary identifier C-RNTI, the terminal device monitors the PDCCH corresponding to the C-RNTI, and the DCI is carried by the PDCCH corresponding to the C-RNTI. The C-RNTI is the C-RNTI of the terminal device. When the indication information indicates not monitoring the PDCCH corresponding to the C-RNTI, the terminal device does not monitor the PDCCH corresponding to the C-RNTI.

[0017] Based on this possible implementation example, the access network device may indicate to the terminal device to monitor the PDCCH corresponding to the C-RNTI only when the terminal device obtains a data transmission request, and may indicate to the terminal device not to monitor the PDCCH corresponding to the C-RNTI when the terminal device has not obtained a data transmission request. This promotes reducing the power consumption of the terminal device.

[0018] In another possible implementation example, by default, the terminal device may alternatively monitor the PDCCH corresponding to the C-RNTI.

[0019] In a possible implementation example, the first random access is a 4-step random access, and the indication information is carried in message 4 of the first random access, or the first random access is a 2-step random access, and the indication information is carried in message B of the first random access. Based on this possible implementation example, it is possible for the indication information to be carried in an existing message, and no new message is added to carry the indication information. This facilitates implementation.

[0020] In a possible implementation example, when the indication information is the first RRC release message and the first RRC release message does not carry the next-hop chain number NCC indication, the inactive-radio network temporary identifier I-RNTI, or the pause setting, the indication information indicates monitoring the PDCCH corresponding to the C-RNTI, and the pause setting indicates to the terminal device to stay in the RRC inactive state.

[0021] Based on this possible implementation example, whether the terminal device monitors the PDCCH corresponding to the C-RNTI may be implicitly indicated. In this way, no new signaling is required to indicate to the terminal device whether to monitor the PDCCH corresponding to the C-RNTI, thereby reducing transmission resources.

[0022] In another possible implementation example, the indication information may alternatively explicitly indicate whether the terminal device monitors the PDCCH corresponding to the C-RNTI.

[0023] In a possible implementation example, when the first condition is satisfied, the terminal device stops monitoring the PDCCH corresponding to the C-RNTI, and the DCI is carried by the PDCCH corresponding to the C-RNTI. The first condition is one of the conditions that a beam failure occurs and a timer expires. The timer is used to control the terminal device to monitor the PDCCH of the C-RNTI. The beam failure includes any one of the following: the reference signal received power of the first received beam is less than the first threshold, or the continuous N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2, or within the first time period, the continuous N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2.

[0024] Based on this possible implementation example, when a beam failure occurs in the first received beam or the probability that the signal reception quality of the first received beam has already deteriorated is high, in order to reduce the power consumption of the terminal device, it is possible to timely stop monitoring the PDCCH corresponding to the C-RNTI.

[0025] In a possible implementation example, when the first condition is satisfied, the terminal device stops monitoring the PDCCH corresponding to the C-RNTI, and the DCI is carried on the PDCCH corresponding to the C-RNTI. The first condition is one of the conditions that a beam failure occurs and a timer expires. The timer is used to control the terminal device to monitor the PDCCH of the C-RNTI, or the timer is used to control the validity of the transmission beam. The beam failure includes that the reference signal received power (RSRP) of the first received beam is less than the first threshold, or the continuous N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2, or within the first time period, the continuous N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2, or the reference signal received power (RSRP) of the received beam corresponding to the first transmission beam is less than the second threshold, or the continuous N RSRPs of the received beam corresponding to the first transmission beam are less than the second threshold, where N is an integer greater than or equal to 2, or within the first time period, the continuous N RSRPs of the received beam corresponding to the first transmission beam are less than the second threshold, where N is an integer greater than or equal to 2, including any one of them.

[0026] Based on this possible implementation example, when a beam failure occurs in the first received beam or the probability that the signal reception quality of the first received beam has already deteriorated is high, in order to reduce the power consumption of the terminal device, it is possible to timely stop monitoring the PDCCH corresponding to the C-RNTI. Instead, based on this possible implementation example, when a beam failure occurs in the first transmission beam or the first transmission beam is invalid, in order to reduce the power consumption of the terminal device, it is possible to timely stop monitoring the PDCCH corresponding to the C-RNTI.

[0027] In a possible implementation example, when the first condition is satisfied, the terminal device performs a second random access. By performing the second random access when the above first condition is satisfied, the beam can be updated in time.

[0028] In the first possible implementation example, after the random access message 4 is received, the timer is started or restarted.

[0029] In the second possible implementation example, after the random access message B is received, the timer is started or restarted.

[0030] In the third possible implementation example, after the DCI corresponding to the C-RNTI is received, the timer is started or restarted. In the present embodiment of the present application, the DCI corresponding to the C-RNTI is the DCI transmitted to the terminal device.

[0031] In the fourth possible implementation example, after the transmission is performed based on the transmission resource indicated by the DCI corresponding to the C-RNTI by the terminal device, the timer is started or restarted.

[0032] In a possible implementation example, the terminal device may further receive second indication information transmitted by the access network device, and the second indication information indicates the length of the timer. Based on this possible implementation example, it is possible to flexibly control the length of the timer. Alternatively, the length of the timer may be specified in advance by the protocol.

[0033] In a possible implementation example, the first random access and the second random access are four-step random accesses. The message 2 of the first random access includes the first Temporary C-RNTI. The message 3 of the second random access carries the C-RNTI of the terminal device, and the C-RNTI of the terminal device is the same as the first Temporary C-RNTI. The PDCCH of the message 4 of the second random access is scrambled using the C-RNTI of the terminal device.

[0034] In this possible implementation example, the C-RNTI of the terminal device is the first Temporary C-RNTI in the current data transmission process. In this way, the access network device may transmit the C-RNTI (i.e., the first Temporary C-RNTI) to the second access network device (i.e., the last serving gNB) only once in the current data transmission process. In this way, it is possible to avoid the potential risk of security inconsistency, and it is possible to reduce the signaling handover between the two access network devices.

[0035] In a possible implementation example, the first random access and the second random access are two-step random accesses. The message B of the first random access contains the first C-RNTI. The message A of the second random access carries the C-RNTI of the terminal device, and the C-RNTI of the terminal device is the same as the first C-RNTI. The PDCCH of the message B of the second random access is scrambled using the C-RNTI of the terminal device.

[0036] In this possible implementation example, the C-RNTI of the terminal device is the first C-RNTI of the message B of the first random access. In this way, the access network device may transmit the C-RNTI (i.e., the first C-RNTI) to the second access network device (i.e., the last serving gNB) only once in the current data transmission process. This helps to avoid the potential risk of security inconsistency and reduce the signaling handover between the two access network devices.

[0037] In a possible implementation example, the first reception beam corresponds to the first preamble, or the first reception beam corresponds to the time-frequency resource of the first preamble. The first random access is a 4-step random access, and the first preamble is the preamble of message 1 of the first random access, or the first random access is a 2-step random access, and the first preamble is the preamble of message A of the first random access. The first preamble corresponds to the first SSB, or the time-frequency resource of the first preamble corresponds to the first SSB. The first reception beam, the reception beam of the first random access, and the reception beam of the first SSB are the same. By performing downlink transmission using a beam that is the same as the reception beam of the first SSB, it promotes improving the signal reception quality of the terminal device.

[0038] In a possible implementation example, the DCI indicates a downlink transmission resource. The terminal device may further transmit a hybrid automatic repeat request (HARQ) feedback to the access network device, and the transmission beam of the HARQ feedback is the same as the first transmission beam. Based on this possible implementation example, the terminal device performs the current transmission in the RRC inactive state using the beam transmitted previously. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam, thereby reducing the power consumption of the terminal device.

[0039] In a possible implementation example, the DCI indicates an uplink transmission resource. The terminal device may further receive a hybrid automatic repeat request (HARQ) feedback transmitted by the access network device, and the reception beam of the HARQ feedback is the same as the first reception beam. Based on this possible implementation example, the terminal device performs the current transmission in the RRC inactive state using the beam transmitted previously. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam, thereby reducing the power consumption of the terminal device.

[0040] According to a second aspect, the present application provides a communication method. The method includes a terminal device transmitting, in a radio resource control inactive (RRC inactive) state, an RRC recovery request and first uplink data to an access network device through a first configured grant (CG) resource using a first transmission beam. The first transmission beam is the same as the transmission beam of a terminal device in an RRC connected state, or the first transmission beam is the same as the transmission beam of a previous data transmission process when the terminal device was in the RRC inactive state.

[0041] In the method described in the second aspect, the terminal device performs current transmission in the RRC inactive state using a previously transmitted beam. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam, thereby reducing the power consumption of the terminal device.

[0042] In a possible implementation, the terminal device may further receive a first response transmitted by the access network device for the RRC recovery request and the first uplink data using a first reception beam. The first reception beam is the same as the reception beam of a terminal device in an RRC connected state, or the first reception beam is the same as the reception beam of a previous data transmission process when the terminal device was in the RRC inactive state, or the first reception beam is a reception beam associated with the first CG resource.

[0043] Based on this possible implementation, the terminal device performs current transmission in the RRC inactive state using a previously transmitted beam. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam, thereby reducing the power consumption of the terminal device.

[0044] In a possible implementation example, the first response is the first Hybrid Automatic Repeat reQuest (HARQ) feedback. When the HARQ feedback is a Negative Acknowledgment (NACK), the terminal device may further re-transmit the Radio Resource Control (RRC) recovery request and the first uplink data to the access network device through the second Coordinated Grant (CG) resource. The transmission beam for re-transmitting the RRC recovery request and the first uplink data is the same as the transmission beam of the previous uplink transmission.

[0045] Based on this possible implementation example, the terminal device performs the current transmission in the RRC inactive state using the beam previously transmitted. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam, thereby reducing the power consumption of the terminal device.

[0046] In a possible implementation example, the first response is the first Hybrid Automatic Repeat reQuest (HARQ) feedback. When the HARQ feedback is an Acknowledgment (ACK), the terminal device may further transmit the second uplink data to the access network device through the second Coordinated Grant (CG) resource. The transmission beam of the second uplink data is the same as the transmission beam of the previous uplink transmission, and the second uplink data is different from the first uplink data.

[0047] Based on this possible implementation example, the terminal device performs the current transmission in the RRC inactive state using the beam previously transmitted. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam, thereby reducing the power consumption of the terminal device.

[0048] In a possible implementation example, the first response is a dynamic grant DG. When DG indicates a retransmission, the terminal device may further retransmit the RRC recovery request and the first uplink data to the access network device, and the transmission beam for retransmitting the RRC recovery request and the first uplink data is the same as the transmission beam of the previous uplink transmission. When DG indicates a new transmission, the terminal device may further transmit the second uplink data to the access network device, and the transmission beam of the second uplink data is the same as the transmission beam of the previous uplink transmission. The second uplink data is different from the first uplink data.

[0049] Based on this possible implementation example, the terminal device performs retransmission or new transmission in the RRC inactive state using the beam transmitted previously. In this way, it is not necessary for the terminal device to perform a series of operations such as beam measurement and measurement result reporting to determine the transmission beam used for retransmission or new transmission, thereby reducing the power consumption of the terminal device.

[0050] In a possible implementation example, the terminal device receives the indication information transmitted by the access network device. When the indication information indicates that a beam that is the same as the transmission beam of the previous uplink transmission is used for performing uplink transmission, the terminal device may perform uplink transmission of subsequent uplink transmissions using a beam that is the same as the transmission beam of the previous uplink transmission. For example, after the first response is received, the RRC recovery request and the first uplink data may be retransmitted or the second uplink data may be newly transmitted, and the transmission may be performed using a beam that is the same as the transmission beam of the previous uplink transmission.

[0051] When the indication information indicates that a beam that is the same as the transmission beam of a previous uplink transmission is not used for the uplink transmission, the terminal device may not perform the uplink transmission of subsequent uplink transmissions using a beam that is the same as the transmission beam of the previous uplink transmission. For example, the first response is the first hybrid automatic repeat request (HARQ) feedback. When the HARQ feedback is a negative acknowledgment (NACK), the terminal device may retransmit the radio resource control (RRC) recovery request and the first uplink data to the access network device through a second control resource (CG) resource. The transmission beam for retransmitting the RRC recovery request and the first uplink data is different from the transmission beam of the previous uplink transmission. In another example, the first response is the first HARQ feedback. When the HARQ feedback is an acknowledgment (ACK), the terminal device may transmit second uplink data to the access network device through a second CG resource. The transmission beam of the second uplink data is the same as the transmission beam of the previous uplink transmission, and the second uplink data is different from the first uplink data. In another example, the first response is a dynamic grant (DG). When the DG indicates a retransmission, the terminal device may retransmit the RRC recovery request and the first uplink data to the access network device, and the transmission beam for retransmitting the RRC recovery request and the first uplink data is different from the transmission beam of the previous uplink transmission. When the DG indicates a new transmission, the terminal device may transmit second uplink data to the access network device, and the transmission beam of the second uplink data is different from the transmission beam of the previous uplink transmission. The second uplink data is different from the first uplink data.

[0052] Based on this possible implementation example, it can be found that the access network device can flexibly control the beam used by the terminal device.

[0053] In a possible implementation example, the terminal device monitors a Physical Downlink Control Channel (PDCCH) corresponding to a Cell Radio Network Temporary Identifier (C-RNTI) or a Configured Scheduling Radio Network Temporary Identifier (CS-RNTI). The PDCCH carries a first response or Downlink Control Information (DCI) indicating a transmission resource for the first response, and the C-RNTI or CS-RNTI is the C-RNTI or CS-RNTI of the terminal device. When a first condition is satisfied, the terminal device stops monitoring the PDCCH corresponding to the C-RNTI or CS-RNTI.

[0054] The first condition includes any one of the conditions that a beam failure occurs and a timer expires. The timer is used to control the terminal device to monitor the PDCCH of the C-RNTI or CS-RNTI, or the timer is used to control the validity of the transmission beam. The beam failure includes any one of the following: the Reference Signal Received Power (RSRP) of the first received beam is less than a first threshold; the consecutive N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2; within a first time period, the consecutive N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2; the RSRP of the received beam corresponding to the first transmitted beam is less than a second threshold; the consecutive N RSRPs of the received beam corresponding to the first transmitted beam are less than the second threshold, where N is an integer greater than or equal to 2; within a first time period, the consecutive N RSRPs of the received beam corresponding to the first transmitted beam are less than the second threshold, where N is an integer greater than or equal to 2.

[0055] Based on this possible implementation example, if there is a problem with the beam in the first received beam, or if the probability that the signal reception quality of the first received beam has already deteriorated is high, in order to reduce the power consumption of the terminal device, it is possible to timely stop monitoring the PDCCH corresponding to the C-RNTI. Instead, based on this possible implementation example, if there is a problem with the beam in the first transmitted beam, or if the first transmitted beam is invalid, in order to reduce the power consumption of the terminal device, it is possible to timely stop monitoring the PDCCH corresponding to the C-RNTI.

[0056] In a possible implementation example, when the first condition is satisfied, the terminal device performs random access. When the above first condition is satisfied, the terminal device can update the beam in time by performing random access.

[0057] In a possible implementation example, after the PDCCH of the C-RNTI is received, the timer is started or restarted. Instead, after the terminal device performs data transmission based on the CG resource, the timer is started or restarted.

[0058] In a possible implementation example, the terminal device may further receive second indication information transmitted by the access network device, and the second indication information indicates the length of the timer. Based on this possible implementation example, it is possible to flexibly control the length of the timer. Instead, the length of the timer may be specified in advance by the protocol.

[0059] In a possible implementation example, the random access is a 4-step random access. The random access message 3 carries the C-RNTI of the terminal device. The PDCCH of the random access message 4 is scrambled using the C-RNTI of the terminal device. In this possible implementation example, the C-RNTI of the terminal device remains unchanged during the current data transmission process. In this way, the access network device may send the C-RNTI to the second access network device (i.e., the last serving gNB) only once during the current data transmission process. In this way, it is possible to avoid the potential risk of security inconsistency, and it is possible to reduce the signaling handover between the two access network devices.

[0060] In a possible implementation example, the random access is a 2-step random access. The random access message A contains the C-RNTI of the terminal device. The PDCCH of the random access message B is scrambled using the C-RNTI of the terminal device. In this possible implementation example, the C-RNTI of the terminal device remains unchanged during the current data transmission process. In this way, the access network device may send the C-RNTI to the second access network device (i.e., the last serving gNB) only once during the current data transmission process. In this way, it is possible to avoid the potential risk of security inconsistency, and it is possible to reduce the signaling handover between the two access network devices.

[0061] According to a third aspect, the present application provides a communication method. The method includes a first access network device receiving a second message 1 transmitted by a terminal device in a radio resource control inactive (RRC inactive) state, where the second message 1 includes a second preamble. The first access network device transmits a second message 2 to the terminal device, and the second message 2 includes a second cell radio network temporary identifier (C-RNTI). The first access network device receives a second message 3 transmitted by the terminal device, and the second message 3 includes the C-RNTI of the terminal device. The first access network device transmits a second message 4 to the terminal device, and the physical downlink control channel (PDCCH) of the second message 4 is scrambled by the C-RNTI of the terminal device.

[0062] Based on the method described in the third aspect, the C-RNTI of the terminal device remains unchanged during the current data transmission process. In this way, the first access network device may transmit the C-RNTI to a second access network device (i.e., the last serving gNB) only once during the current data transmission process. In this way, it is possible to avoid the potential risk of security inconsistency and reduce the signaling handover between the two access network devices.

[0063] Optionally, a second Temporary C-RNTI is used for the retransmission scheduling of the second MSG3.

[0064] In a possible implementation example, before the first access network device receives the second message 1 sent by a terminal device in the radio resource control inactive (RRC inactive) state, the first access network device receives the first message 1 sent by the terminal device in the radio resource control inactive (RRC inactive) state, and the first message 1 includes a first preamble. The first access network device sends the first message 2 to the terminal device, and the first message 2 includes a first Temporary C-RNTI. The first access network device receives the first message 3 sent by the terminal device, and the first message 3 includes a radio resource control (RRC) recovery request and first uplink data. The first access network device sends the first message 4 to the terminal device, and the 1 first message 4 includes collision resolution. The first access network device sends the first Temporary C-RNTI to the second access network device, and the C-RNTI of the terminal device is the first Temporary C-RNTI.

[0065] In this possible implementation example, the C-RNTI of the terminal device is the first Temporary C-RNTI in the current data transmission process. In this way, the first access network device may send the C-RNTI (i.e., the first Temporary C-RNTI) to the second access network device (i.e., the last serving gNB) only once in the current data transmission process. In this way, it is possible to avoid the potential risk of security inconsistency, and it is possible to reduce the signaling transfer between the two access network devices.

[0066] According to a fourth aspect, the present application provides a communication method. The method includes a first access network device receiving a second message A sent by a terminal device in a radio resource control inactive (RRC inactive) state, where the second message A includes a second preamble and a cell radio network temporary identifier (C-RNTI) of the terminal device. The first access network device sends a second message B to the terminal device, and the physical downlink control channel (PDCCH) of the second message B is scrambled by the C-RNTI of the terminal device.

[0067] Based on the method described in the fourth aspect, the C-RNTI of the terminal device remains unchanged during the current data transmission process. In this way, the access network device may send the C-RNTI to a second access network device (i.e., the last serving gNB) only once during the current data transmission process. In this way, it is possible to avoid potential risks of security inconsistencies and reduce the signaling handover between two access network devices.

[0068] In a possible implementation example, before the first access network device receives the second message A sent by the terminal device in the RRC inactive state, the first access network device receives a first message A sent by the terminal device in the RRC inactive state, where the first message A includes a first preamble, a radio resource control (RRC) recovery request, and first uplink data. The first access network device sends a first message B to the terminal device, and the 1 first message B includes collision resolution and a first C-RNTI. The first access network device sends the first C-RNTI to the second access network device, and the C-RNTI of the terminal device is the first C-RNTI.

[0069] In this possible implementation example, the C-RNTI of the terminal device is the first C-RNTI of the message B of the first random access. In this way, the first access network device may send the C-RNTI (i.e., the first C-RNTI) to the second access network device (i.e., the last serving gNB) only once in the current data transmission process. This helps avoid potential risks of security inconsistencies and promotes reducing the signaling handover between the two access network devices.

[0070] According to a fifth aspect, the present application provides a communication method. The method includes a terminal device receiving second information sent by a network device, where the second information is used to notify the terminal device to recover the SCG. The terminal device recovers or activates the SCG. If the timing advance timer has not expired, is not stopped, or is not released, the terminal device transmits PUCCH or PUSCH to the SCG, and the transmission beam of the PUCCH and PUSCH is the same as the transmission beam of the previous uplink transmission, or the terminal device monitors the PDCCH of the SCG. The reception beam used to monitor the PDCCH of the SCG is the same as the reception beam used to monitor the PDCCH in the previous SCG.

[0071] In the method described in the fifth aspect, the terminal device performs transmission to the SCG using the beam previously transmitted. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam, thereby reducing the power consumption of the terminal device.

[0072] According to a sixth aspect, the present application provides a communication device. The device may be a terminal device, a device within a terminal device, or a device that can be used together with a terminal device. Alternatively, the communication device may be a chip system. The communication device may perform the method according to the first aspect, the second aspect, or the fifth aspect. The functions of the communication device may be implemented by hardware or may be implemented by executing corresponding software by the hardware. The hardware or software includes one or more units or modules corresponding to the above functions. The unit or module may be software and / or hardware. For the operations performed by the communication device and its beneficial effects, reference is made to the method according to the first aspect, the second aspect, or the fifth aspect and its beneficial effects. Duplicate content will not be described repeatedly.

[0073] According to a seventh aspect, the present application provides a communication device. The device may be a first access network device, a device within the first access network device, or a device that can be used together with the first access network device. Alternatively, the communication device may be a chip system. The communication device can perform the method according to the third aspect or the fourth aspect. The functions of the communication device may be implemented by hardware or may be implemented by executing corresponding software by the hardware. The hardware or software includes one or more units or modules corresponding to the above functions. The unit or module may be software and / or hardware. For the operations performed by the communication device and its beneficial effects, reference is made to the method according to the third aspect or the fourth aspect and its beneficial effects. Duplicate content will not be described repeatedly.

[0074] According to an eighth aspect, the present application provides a communication device. The communication device includes a processor. When the processor calls a computer program in the memory, the method according to any one of the first aspect to the fifth aspect is performed.

[0075] According to the ninth aspect, the present application provides a communication device. The communication device includes a processor and a memory, and the processor and the memory are connected. The processor is configured to implement the method according to any one of the first aspect to the fifth aspect.

[0076] According to the tenth aspect, the present application provides a communication device. The communication device includes a processor and an interface circuit. The interface circuit is configured to receive a signal from another communication device other than the communication device and transmit the signal to the processor, or transmit a signal from the processor to another communication device other than the communication device. The processor is configured to implement the method according to any one of the first aspect to the fifth aspect by using a logic circuit or by executing code instructions.

[0077] According to the eleventh aspect, the present application provides a computer-readable storage medium. The storage medium stores a computer program or instructions, and when the computer program or instructions are executed by a communication device, the method according to any one of the first aspect to the fifth aspect is implemented.

[0078] According to the twelfth aspect, the present application provides a computer program product including instructions. When a computer reads and executes the computer program product, the computer can perform the method according to any one of the first aspect to the fifth aspect.

Brief Description of the Drawings

[0079]

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Embodiments for Carrying Out the Invention

[0080] Hereinafter, specific embodiments of the present application will be further described in detail with reference to the accompanying drawings.

[0081] In the specification, claims and accompanying drawings of the present application, terms such as "first", "second", etc. are intended to distinguish different things, while not indicating a specific order. In addition, the terms "including" and "having" and any other variants thereof are intended to cover including others as well. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but may further optionally include steps or units not listed in the process, method, product or device, or may further optionally include other steps or units that should be naturally included.

[0082] The "embodiments" described in this specification mean that specific features, structures or characteristics described with reference to these embodiments may be included in at least one embodiment of the present application. The phrases shown in various places in this specification do not necessarily refer to the same embodiment, and are neither independent embodiments that do not intersect with other embodiments nor optional embodiments. It is explicitly or implicitly understood by those skilled in the art that the embodiments described in this specification may be combined with other embodiments.

[0083] In this application, "at least one (thing)" means one or more, "a plurality of" means two or more, "at least two (things)" means two, three, or four or more, and "and / or" is used to describe the relationship between related items and indicates that there may be three relationships. For example, "A and / or B" may indicate three cases: only A exists, only B exists, or both A and B exist, and A and B may be singular or plural. The symbol " / " often indicates the "or" relationship between related items. "At least one of the following thing(s)" or a similar expression refers to any combination of these things and includes one thing (one) or any combination of a plurality of things (plural). 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", and a, b, and c may be singular or plural.

[0084] In order to reduce the power consumption of a terminal device when data is transmitted in the RRC inactive state, embodiments of this application provide a communication method and a communication device. To better understand the solutions provided in this application, the technical terms of this application (three types of RRC states of the terminal device) will be described first below.

[0085] 1. Radio Resource Control Connected (RRC connected) state: In the RRC connected state, there is a dedicated RRC connection between the terminal device and the access network device. This dedicated RRC connection is a connection of a Data Radio Bearer (DRB) or a Signalling Radio Bearer 1 (SRB1).

[0086] 2. Radio Resource Control Idle (RRC idle) state: In the RRC idle state, there is no dedicated RRC connection between the terminal device and the access network device.

[0087] 3. Radio Resource Control Inactive (RRC inactive) state: In the RRC inactive state, the dedicated RRC connection between the terminal device and the access network device is suspended. Similar to the RRC idle state, in the RRC inactive state, the terminal device can only receive content (paging and broadcast) in the common search space and may perform cell reselection. In addition, cell reselection in the RRC inactive state is the same as cell reselection in the RRC idle state. In the RRC inactive state, the terminal device may move within the radio access network based notification area (RNA) without notifying the access network device. Since the terminal device in the RRC inactive state suspends data processing, a power consumption level similar to that of the RRC idle state can be obtained in the RRC inactive state. The terminal device stores the context of the terminal device, and the access network device that previously provided the service stores the context of the terminal device and the NG connection related to the access and mobility management function (AMF) and the user plane function (UPF). The dedicated RRC connection between the terminal device and the access network device may be suspended and then resumed. Since the terminal device in the RRC inactive state can quickly switch to the RRC connected state using the RRC resume procedure, the data transmission recovery delay of the terminal device in the RRC inactive state can be reduced.

[0088] Hereinafter, the system architecture of the embodiments of the present application will be described.

[0089] FIG. 1 is a schematic diagram of a system architecture according to an embodiment of the present application. As shown in FIG. 1, the system architecture includes a terminal device and an access network device. In FIG. 1, one terminal device and one access network device are used as examples. The system architecture may further include a plurality of terminal devices or may further include a plurality of access network devices.

[0090] 1. Terminal device A terminal device may also be referred to as a user equipment (UE), and includes devices that provide voice and / or data connectivity to a user. For example, it may include a handheld device with a wireless connection function, or a processing device connected to a wireless modem. The terminal device can communicate with the core network through a radio access network (RAN) and exchange voice and / or data with the RAN. The terminal device may include a wireless terminal device, a mobile terminal device, a device-to-device (D2D) terminal device, a vehicle-to-everything (V2X) terminal device, a machine-to-machine / machine-type communications (M2M / MTC) terminal device, an Internet of Things (IoT) terminal device, a subscriber unit, a subscriber station, a mobile station, a remote station, an access point (AP), a remote terminal, an access terminal, a user terminal, a user agent, a user equipment, etc. For example, the terminal device may include a mobile phone (or a device called a "cellular" phone), a computer with a mobile terminal device, or a mobile device that is portable, pocket-sized, handheld, or built into a computer. For example, the terminal device may be a device such as a personal communication service (PCS) phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, or a personal digital assistant (PDA). The terminal device may alternatively include a device with limitations, such as a low-power consumption device, a device with limited storage capacity, or a device with limited computing power.For example, the terminal device includes information sensing devices such as barcodes, radio frequency identification (RFID), sensors, global positioning system (GPS), and laser scanners.

[0091] In the embodiments of the present application, the device configured to implement the functions of the terminal device may be the terminal device itself, or a device that can support the terminal device when implementing the functions, for example, a chip system capable of implementing the functions of the terminal device, or a combined component or device. This device may be installed in the terminal device. In the embodiments of the present application, the chip system may include a chip, or may include a chip and another discrete component. In the technical solutions provided in the embodiments of the present application, an example where the device configured to implement the functions of the terminal is the terminal device is used to explain the technical solutions provided in the embodiments of the present application.

[0092] 2. Access Network Device An access network device is a node or device that connects a terminal device to a wireless network, and the access network device may sometimes be referred to as a base station. For example, the access network device includes, but is not limited to, the next-generation Node B (gNB) of a 5G communication system, evolved Node B (eNB), radio network controller (RNC), Node B (NB), base station controller (BSC), base transceiver station (BTS), home evolved Node B (HeNB) or home Node B (HNB), baseband unit (BBU), transmitting and receiving point (TRP), transmitting point (TP), and mobile switching center.

[0093] In the embodiments of this application, a device configured to implement the functions of an access network device may be an access network device, or a device capable of supporting an access network device when implementing the functions, for example, a chip system capable of implementing the functions of an access network device, or a combined component or device. This device may be installed in an access network device. In the technical solution provided in the embodiments of this application, an example in which a device configured to implement the functions of an access network device is an access network device is used to illustrate the technical solution provided in the embodiments of this application.

[0094] The interface between the access network device and the terminal device may be a Uu interface (or also called an air interface). Of course, in future communications, the name of the interface may remain unchanged, or it may be replaced with other names. This is not limited in this application. For example, the communication between the access network device and the terminal device follows a specific protocol layer structure. For example, the control plane protocol layer structure may include an RRC layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, a media access control (MAC) layer, and a physical layer. The user plane protocol layer structure may include a PDCP layer, an RLC layer, a MAC layer, and a physical layer. In a possible implementation example, a service data adaptation protocol (SDAP) layer may further be included above the PDCP layer.

[0095] The access network device may implement the functions of protocol layers such as the RRC layer, PDCP layer, RLC layer, and MAC layer through one node or multiple nodes. For example, in the evolved architecture, the access network device may include one or more centralized units (CUs) and one or more distributed units (DUs), and multiple DUs may be centrally controlled by one CU. For example, the interface between the CU and the DU may be called the F1 interface. The control plane (CP) interface may be the F1-C interface, and the user plane (UP) interface may be the F1-U interface. The CU and DU may be obtained through division based on the protocol layers of the radio network. For example, as shown in Figure 2a, the functions of the PDCP layer and the protocol layers above the PDCP layer are set in the CU, and the functions of the protocol layers below the PDCP layer (for example, the RLC layer and the MAC layer) are set in the DU.

[0096] The division of the processing functions of the CU and DU based on the protocol layer is only an example, and the processing functions may be divided in another way. In one example, the functions of the protocol layers above the RLC layer are set in the CU, and the functions of the RLC layer and the protocol layers below the RLC layer are set in the DU. In another example, the CU or DU may be further divided into functions including more protocol layers. In another example, the CU or DU may be further divided into some processing functions including multiple protocol layers. In one design example, some functions of the RLC layer and the functions of the protocol layers above the RLC layer are set in the CU, and the remaining functions of the RLC layer and the functions of the protocol layers below the RLC layer are set in the DU. In another design example, the division of the functions of the CU or DU may be alternatively performed based on the service type or other system requirements. For example, the division may be performed based on the delay. The functions whose processing time needs to meet the delay requirement are set in the DU, and the functions whose processing time does not need to meet the delay requirement are set in the CU. In another design example, the CU may alternatively have one or more functions of the core network. For example, the CU may be set on the network side to facilitate centralized management, and there may be multiple radio frequency functions in the DU or the radio frequency functions may be set in remote locations. This is not limited in the embodiments of the present application.

[0097] For example, the functions of the CU may be implemented by one entity or different entities. For example, as shown in FIG. 2b, the functions of the CU may be further divided. More specifically, the control plane and the user plane may be separated, and the control plane and the user plane are implemented using different entities, namely, a control plane CU entity (i.e., a CU-CP entity) and a user plane CU entity (i.e., a CU-UP entity). The CU-CP entity and the CU-UP entity can be connected to the DU to jointly complete the functions of the access network device. The interface between the CU-CP entity and the CU-UP entity may be an E1 interface, the interface between the CU-CP entity and the DU may be an F1-C interface, and the interface between the CU-UP entity and the DU may be an F1-U interface. One DU and one CU-UP may be connected to one CU-CP. Under the control of the same CU-CP, one DU may be connected to multiple CU-UPs, and one CU-UP may be connected to multiple DUs.

[0098] In the architecture shown in FIGS. 2a and 2b, it should be noted that the signaling generated by the CU may be transmitted to the terminal device via the DU, or the signaling generated by the terminal device may be transmitted to the CU via the DU. By directly encapsulating the signaling at the protocol layer without parsing the signaling, the DU may transparently transmit the signaling to the terminal device or the CU. In the following embodiments, when such transmission of signaling between the DU and the terminal device is included, the transmission or reception of signaling by the DU includes this scenario. For example, signaling in the RRC layer or the PDCP layer is finally processed as data in the physical layer and transmitted to the terminal device, or is converted from the data received in the physical layer. In this architecture, it can also be considered that the signaling in the RRC layer or the PDCP layer is transmitted by the DU or transmitted by the DU and the high-frequency device.

[0099] Hereinafter, the communication method and communication device provided in this application will be described in detail.

[0100] FIG. 3 is a schematic flowchart of a communication method according to an embodiment of this application. As shown in FIG. 3, the communication method includes the following steps 301 and 302. The method shown in FIG. 3 may be performed by a first access network device and a terminal device. Alternatively, the method shown in FIG. 3 may be performed by a chip of the first access network device and a chip of the terminal device. In FIG. 3, the first access network device and the terminal device are used as examples for explanation. The execution entities of the following flowcharts are similar. Details will not be repeated hereinafter.

[0101] 301: The first access network device transmits downlink control information (DCI) to the terminal device.

[0102] In the present embodiment of the present application, after entering the RRC inactive state, when it is necessary for the terminal device to transmit user data, the terminal device may initiate a first random access and start an RA (Random Access) data transmission process. After the first random access is completed, the first access network device transmits DCI to the terminal device, and the DCI allocates uplink transmission resources or downlink transmission resources. The first random access may be a four-step random access or a two-step random access. When the first random access is a four-step random access, refer to the description of the subsequent embodiment corresponding to FIG. 4 for the procedure of the first random access. When the first random access is a two-step random access, refer to the description of the subsequent embodiment corresponding to FIG. 5 for the procedure of the first random access.

[0103] In the embodiment of the present application, the first access network device transmits DCI using a second transmission beam, and the second transmission beam is the same as the transmission beam for the downlink transmission of the first random access.

[0104] Throughout the full text of the embodiment of the present application, the fact that the beams are the same means quasi-colocation of transmission. For example, when the receiving beams are the same, the receiving beam of information 1 and the receiving beam of information 2 are the same. In particular, information 2 is received using the same spatial domain transmission filter or spatial domain parameters of information 1. For example, when the transmitting beams are the same, the transmitting beam of information 1 and the transmitting beam of information 2 are the same. In particular, information 2 is transmitted using the same spatial domain transmission filter of information 1.

[0105] In a possible implementation example, when the first random access is a 4-step random access, the second transmission beam is the same as the transmission beam of message 2 or message 4 of the first random access.

[0106] In a possible implementation example, when the first random access is a 2-step random access, the second transmission beam is the same as the transmission beam of message B of the first random access.

[0107] In a possible implementation example, the second transmission beam corresponds to the first preamble. Instead, the second transmission beam corresponds to the time-frequency resource of the first preamble. The first preamble corresponds to the first SSB, or the time-frequency resource of the first preamble corresponds to the first SSB. The second transmission beam, the transmission beam of the downlink transmission of the first random access, and the transmission beam of the first SSB are the same. For the first SSB, refer to the description of the embodiments corresponding to FIG. 4 or FIG. 5. The transmission is performed using a beam that is the same as the transmission beam of the first SSB. This promotes improving the signal reception quality of the terminal device.

[0108] 302: After successfully performing the first random access in the RRC inactive state, the terminal device receives the DCI sent by the first access network device using the first reception beam, and the first reception beam is the same as the reception beam of the downlink transmission of the first random access.

[0109] In a possible implementation example, when the first random access is a 4-step random access, the first reception beam is the same as the reception beam of message 2 or message 4 of the first random access.

[0110] In another possible implementation example, when the first random access is a 2-step random access, the first reception beam is the same as the reception beam of message B of the first random access.

[0111] In a possible implementation example, the first reception beam corresponds to the first preamble. Alternatively, the first reception beam corresponds to the time-frequency resource of the first preamble. The first preamble corresponds to the first SSB, or the time-frequency resource of the first preamble corresponds to the first SSB. The first reception beam, the reception beam of the first downlink random access transmission, and the reception beam of the first SSB are the same. By performing transmission using a beam that is the same as the reception beam of the first SSB, it promotes improving the signal reception quality of the terminal device.

[0112] In a possible implementation example, the DCI indicates a downlink transmission resource or an uplink transmission resource. When the DCI indicates a downlink transmission resource, after receiving the DCI, the terminal device may further perform downlink transmission through the downlink transmission resource, and the reception beam of the downlink transmission is the same as the first reception beam. Correspondingly, the first access network device may perform downlink transmission through the downlink transmission resource, and the transmission beam of the downlink transmission is the same as the second transmission beam.

[0113] When the DCI indicates an uplink transmission resource, after the DCI, uplink transmission may be further performed through the uplink transmission resource using the first transmission beam, and the first transmission beam is the same as the transmission beam of the uplink transmission of the first random access. Correspondingly, the first access network device may receive data through the uplink transmission resource using the second reception beam, and the second reception beam is the same as the reception beam of the uplink transmission of the first random access.

[0114] In this possible implementation example, the terminal device performs downlink transmission or uplink transmission through the downlink transmission resource indicated by the DCI in the RRC inactive state using the beam transmitted previously. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam used for uplink transmission or downlink transmission, thereby reducing the power consumption of the terminal device.

[0115] In a possible implementation example, when the first random access is a 4-step random access, the first transmission beam is the same as the transmission beam of message 1 or message 3 of the first random access.

[0116] In another possible implementation example, when the first random access is a 2-step random access, the first transmission beam is the same as the transmission beam of message A of the first random access.

[0117] In a possible implementation example, when the first random access is a 4-step random access, the second reception beam is the same as the reception beam of message 1 or message 3 of the first random access.

[0118] In another possible implementation example, when the first random access is a 2-step random access, the second reception beam is the same as the reception beam of message A of the first random access.

[0119] In a possible implementation example, after the terminal device performs downlink transmission on the downlink transmission resource indicated by DCI, the terminal device may further transmit HARQ feedback to the first access network device, and the transmission beam of the HARQ feedback is the same as the first transmission beam. The downlink transmission may be to receive a physical downlink shared channel (PDSCH). The HARQ feedback is the HARQ feedback for the downlink transmission. Correspondingly, the first access network device receives the HARQ feedback transmitted by the terminal device, and the reception beam of the HARQ feedback is the second reception beam.

[0120] Based on this possible implementation example, the terminal device transmits HARQ feedback in the RRC inactive state using a previously transmitted beam. In this way, there is no need for the terminal device to perform a series of operations such as beam measurement and measurement result reporting to determine the transmission beam for transmitting HARQ feedback, thereby reducing the power consumption of the terminal device.

[0121] Optionally, the PDSCH received by the terminal device using the first receiving beam through the downlink transmission resource indicated by the DCI may further carry the second RRC release message. The second RRC release message is a response to the RRC recovery request of the first random access. After receiving the second RRC release message, the terminal device terminates the current RA data transmission process.

[0122] In a possible implementation example, after the terminal device performs uplink transmission on the uplink transmission resource indicated by the DCI using the first transmission beam, the terminal device may further receive the HARQ feedback transmitted by the first access network device, and the receiving beam of the HARQ feedback is the same as the first receiving beam. The uplink transmission may be to transmit a physical uplink shared channel (PUSCH). The HARQ feedback is the HARQ feedback for the uplink transmission. Correspondingly, the first access network device transmits the HARQ feedback to the terminal device, and the transmission beam of the HARQ feedback is the same as the second transmission beam.

[0123] Based on this possible implementation example, the terminal device receives HARQ feedback in the RRC inactive state using a previously transmitted beam. In this way, there is no need for the terminal device to perform a series of operations such as beam measurement and measurement result reporting to determine the receiving beam used for receiving HARQ feedback, thereby reducing the power consumption of the terminal device.

[0124] In a possible implementation example, before receiving the DCI transmitted by the first access network device, the terminal device further monitors the PDCCH corresponding to the C-RNTI, and the DCI is carried by the PDCCH corresponding to the C-RNTI. After the PDCCH corresponding to the C-RNTI is monitored, it is possible to receive the DCI from the PDCCH corresponding to the C-RNTI. The PDCCH corresponding to the C-RNTI is a PDCCH scrambled using the C-RNTI. In this specification, the C-RNTI is the C-RNTI of the terminal device.

[0125] In a possible implementation example, by default, the terminal device monitors the PDCCH corresponding to the C-RNTI and monitors the PDCCH of the C-RNTI using the first receiving beam.

[0126] In another possible implementation example, the terminal device may further receive the indication information transmitted by the first access network device. When the indication information indicates to monitor the PDCCH corresponding to the C-RNTI, the terminal device monitors the PDCCH corresponding to the C-RNTI. When the indication information indicates not to monitor the PDCCH corresponding to the C-RNTI, the terminal device does not monitor the PDCCH corresponding to the C-RNTI. In other words, when the first access network device indicates to the terminal device to monitor, the terminal device monitors the PDCCH corresponding to the C-RNTI. This promotes reducing the power consumption of the terminal device.

[0127] In a possible implementation example, the first random access is a 4-step random access, and the indication information is carried in message 4 of the first random access. Based on this possible implementation example, it is possible for the indication information to be carried in an existing message, and no new message is added to carry the indication information. This facilitates implementation. Instead, the first random access is a 4-step random access, and the indication information does not have to be carried in message 4. For example, it may be carried in message 2, or a new message may be separately used to send the indication information.

[0128] In a possible implementation example, the first random access is a 2-step random access, and the indication information is carried in message B of the first random access. Based on this possible implementation example, it is possible for the indication information to be carried in an existing message, and no new message is added to carry the indication information. This facilitates implementation. Instead, the first random access is a 2-step random access, and the indication information does not have to be carried in message B. For example, a new message may be separately used to send the indication information.

[0129] In a possible implementation example, the indication information may implicitly indicate whether to monitor the PDCCH corresponding to the C-RNTI. Instead, the indication information may explicitly indicate whether to monitor the PDCCH corresponding to the C-RNTI.

[0130] 1 Tacit indication: The indication information may be the first RRC release message, and when the first RRC release message does not carry the next hop chain counter (NCC) indication, the inactive - radio network temporary identifier (I - RNTI) or the pause setting, the indication information indicates monitoring the PDCCH corresponding to the C - RNTI, and the pause setting indicates that the terminal device should stay in the RRC inactive state. When the first RRC release message carries the next hop chain counter (NCC) indication, the inactive - radio network temporary identifier (I - RNTI) or the pause setting, the first RRC release message indicates not to monitor the PDCCH corresponding to the C - RNTI. Whether the terminal device monitors the PDCCH corresponding to the C - RNTI is tacitly indicated. In this way, no new signaling is required to indicate to the terminal device whether to monitor the PDCCH corresponding to the C - RNTI, thereby reducing the transmission resources.

[0131] 2 Explicit indication: The explicit indication means an indication of several bits. For example, when the bit of the indication information is 1, it indicates monitoring the PDCCH corresponding to the C - RNTI. When the bit of the indication information is 0, it indicates not monitoring the PDCCH corresponding to the C - RNTI. Instead, the number of bits of the indication information may exceed 1. This is not limited in the embodiments of the present application.

[0132] In a possible implementation example, when the first condition is met, the terminal device stops monitoring the PDCCH corresponding to the C - RNTI. The first condition is one of the conditions that a beam failure occurs and a timer expires. The timer is used to control the terminal device to monitor the PDCCH of the C - RNTI. The beam failure includes any one of the following: the reference signal received power of the first received beam is less than the first threshold, or the continuous N received signal strength reference powers (RSRPs) of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2, or within the first time period, the continuous N received signal strength reference powers (RSRPs) of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2.

[0133] In this possible implementation example, the RSRP of the first received beam is less than the first threshold, or the consecutive N RSRPs of the first received beam are less than the first threshold. the place This indicates that a beam defect has occurred in the first received beam (i.e., the signal reception quality of the first received beam has deteriorated), and it is not possible to continue using the first received beam. After the timer expires, this indicates that the probability that the signal reception quality of the first received beam has already deteriorated is high, and it is not possible to continue using the first received beam. Therefore, based on this possible implementation example, when a beam defect occurs in the first received beam or the probability that the signal reception quality of the first received beam has already deteriorated is high, in order to reduce the power consumption of the terminal device, it is possible to timely stop monitoring the PDCCH corresponding to the C-RNTI.

[0134] In another possible implementation example, when the first condition is satisfied, the terminal device stops monitoring the PDCCH corresponding to the C-RNTI. The first condition is one of the conditions that a beam defect occurs and the timer expires. The timer is used to control the terminal device to monitor the PDCCH of the C-RNTI, or the timer is used to control the validity of the transmission beam. The beam defect includes any one of the following: the reference signal received power RSRP of the first received beam is less than the first threshold, or the consecutive N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2, or within the first time period, the consecutive N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2, or the reference signal received power RSRP of the received beam corresponding to the first transmission beam is less than the second threshold, or the consecutive N RSRPs of the received beam corresponding to the first transmission beam are less than the second threshold, where N is an integer greater than or equal to 2, or within the first time period, the consecutive N RSRPs of the received beam corresponding to the first transmission beam are less than the second threshold, where N is an integer greater than or equal to 2.

[0135] Based on this possible implementation example, when there is a problem with the beam in the first received beam, or when the probability that the signal reception quality of the first received beam has already deteriorated is high, in order to reduce the power consumption of the terminal device, it is possible to timely stop monitoring the PDCCH corresponding to the C-RNTI. Instead, based on this possible implementation example, when there is a problem with the beam in the first transmitted beam, or when the first transmitted beam is invalid, in order to reduce the power consumption of the terminal device, it is possible to timely stop monitoring the PDCCH corresponding to the C-RNTI.

[0136] In a possible implementation example, when the above first condition is satisfied, the terminal device performs a second random access. After the second random access is completed, the terminal device may perform transmission using a beam that is the same as the beam of the second random access. For example, the terminal device may perform downlink transmission using a beam that is the same as the received beam of the second random access, or may perform uplink transmission using a beam that is the same as the transmitted beam of the second random access. Therefore, when the above first condition is satisfied, the terminal device can update the beam in time by performing the second random access.

[0137] In the first possible implementation example, after the random access message 4 is received, the timer is started or restarted. For example, the timer is started after the random access message 4 of the first random access is received, and the timer is restarted after the random access message 4 of the second random access is received.

[0138] In the second possible implementation example, after the random access message B is received, the timer is started or restarted. For example, after the random access message B of the first random access is received, the timer is started, and after the random access message B of the second random access is received, the timer is restarted.

[0139] In a third possible implementation example, after DCI corresponding to the C-RNTI is received, a timer is started or restarted. In the present embodiment of the present application, the DCI corresponding to the C-RNTI is the DCI transmitted to the terminal device. For example, after the first random access is successful, when the terminal device receives the first DCI, the terminal device starts a timer and restarts the timer after receiving the second DCI.

[0140] In a fourth possible implementation example, after transmission is performed based on the transmission resource indicated by the DCI corresponding to the C-RNTI by the terminal device, a timer is started or restarted. For example, after the first random access is successful, the timer is started after the terminal device performs transmission for the first time based on the transmission resource indicated by the DCI corresponding to the C-RNTI, and the timer is restarted after transmission is performed again based on the transmission resource indicated by the DCI corresponding to the C-RNTI.

[0141] In a possible implementation example, the terminal device may further receive second indication information transmitted by the first access network device, and the second indication information indicates the length of the timer. Based on this possible implementation example, it is possible to flexibly control the length of the timer. Alternatively, the length of the timer may be specified in advance by the protocol.

[0142] In a possible implementation example, the first random access and the second random access are four-step random accesses. Message 2 of the first random access includes the first Temporary C-RNTI. Message 3 of the second random access carries the C-RNTI, and the C-RNTI is the same as the first Temporary C-RNTI. The PDCCH of message 4 of the second random access is scrambled using the C-RNTI. When the second random access is a four-step random access, refer to the description of the embodiment corresponding to FIG. 12 for the specific process of the second random access. Details are not described in this description.

[0143] In one of the data transmission processes, a terminal device in the RRC inactive state may perform a plurality of random access processes, and a Temporary C-RNTI is assigned to each of the plurality of random access processes. As described above, after the random access is successful, when the terminal device receives an RRC release message for an RRC recovery request, the current data transmission process ends. In one of the data transmission processes of a terminal device in the RRC inactive state, after the first random access is completed, the terminal device determines the first Temporary C-RNTI (the first Temporary C-RNTI) sent by the first access network device as the C-RNTI. After the first random access is completed, the first access network device sends the first Temporary C-RNTI of the first random access process to a second access network device (i.e., the last serving gNB), so that the second access network device performs security-related operations in the next data transmission process. In another random access process of the data transmission process, the first access network device also assigns a second Temporary C-RNTI (the second Temporary C-RNTI) to the terminal device. However, the C-RNTI is the first Temporary C-RNTI of the first random access, and the terminal device does not use the second Temporary C-RNTI as the C-RNTI. To avoid unnecessary security inconsistency risks, the first access network device does not send the second Temporary C-RNTI to the second access network device. For example, although the first access network device sends the second Temporary C-RNTI to the second access network device in the second random access process, if the terminal device fails to contend successfully in the second random access process, the C-RNTI of the second access network device does not match the C-RNTI.This affects the identity authentication performed by the second access network device on the terminal device in the following data transmission process. Therefore, in this possible implementation example, the C-RNTI is always the first Temporary C-RNTI in the current data transmission process. In this way, the first access network device may send the C-RNTI (i.e., the first Temporary C-RNTI) to the second access network device (i.e., the last serving gNB) only once in the current data transmission process. In this way, it is possible to avoid the potential risk of security inconsistency, and it is possible to reduce the signaling handover between the two access network devices.

[0144] Optionally, a second Temporary C-RNTI may be used to schedule retransmissions for the message 3 of the second random access.

[0145] In a possible implementation example, the first random access and the second random access are two-step random accesses. The message B of the first random access contains the first C-RNTI. The message A of the second random access carries the C-RNTI, and the C-RNTI is the same as the first C-RNTI. The PDCCH of the message B of the second random access is scrambled using the C-RNTI. When the second random access is a two-step random access, refer to the procedure shown in FIG. 14 for the execution procedure of the second random access. Details are not described in this description. In this possible implementation example, the C-RNTI is always the first C-RNTI of the message B of the first random access during the current data transmission process. In this way, the first access network device may transmit the C-RNTI (i.e., the first C-RNTI) to the second access network device (i.e., the last serving gNB) only once during the current data transmission process. In this way, the potential risk of security inconsistency is avoided, and the signaling handover between the two access network devices is reduced.

[0146] Based on the method described in FIG. 3, it can be found that the terminal device performs the current transmission in the RRC inactive state using the previously transmitted beam. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam, thereby reducing the power consumption of the terminal device.

[0147] FIG. 4 is a schematic flowchart of a first random access according to an embodiment of the present application. As shown in FIG. 4, the procedure of the first random access includes the following steps 401 to 404.

[0148] 401: The terminal device transmits a message 1 (MSG1) to the first access network device.

[0149] Message 1 includes a first preamble. The function of the preamble is to notify a first access network device of a random access request, and to enable the first access network device to calculate the transmission delay between the first access network device and the terminal device, whereby the first access network device calibrates the uplink timing and notifies the terminal device of the calibration information using a timing advance command (TA command).

[0150] The first access network device periodically transmits SSBs. The first access network device transmits a plurality of SSBs in each period. There is a correspondence between each SSB of the plurality of SSBs and a random access time-frequency resource (i.e., the time-frequency resource corresponding to the preamble) or the preamble. The terminal device measures the plurality of SSBs and determines a first SSB from the plurality of SSBs, and the reference signal received power (RSRP) of the first SSB is equal to or greater than a threshold value. The first SSB corresponds to the first preamble, or the time-frequency resource of the first preamble corresponds to the first SSB.

[0151] The transmission beam of Message 1 is measured by the terminal device. For example, the transmission beam of Message 1 may be randomly measured by the terminal device, or the RSRP of the reception beam corresponding to the transmission beam of Message 1 is equal to or greater than a threshold value.

[0152] The reception beam of Message 1 is measured by the first access network device. For example, the reception beam of Message 1 may be randomly measured by the first access network device, or the RSRP of the reception beam of Message 1 is equal to or greater than a threshold value.

[0153] 402: The first access network device transmits a message 2 (MSG2) to the terminal device.

[0154] Message 2 may also be referred to as a random access response (RAR). Message 2 includes, but is not limited to, a first temporary cell radio network temporary identifier (first Temporary C-RNTI), an uplink grant (UL grant), and a timing advance command (TA command). The TA command is used to adjust the uplink advance, and the uplink advance is used in the scheduling of subsequent transmissions. The UL grant indicates the transmission resources for message 3.

[0155] In a possible implementation, the reception beam of message 2 corresponds to the first preamble, or the reception beam of message 2 corresponds to the time-frequency resource of the first preamble. The reception beam of message 2 is the same as the reception beam of the first SSB.

[0156] In another possible implementation, the reception beam of message 2 may be measured randomly by the terminal device instead, or the RSRP of the reception beam of message 2 is greater than or equal to a threshold.

[0157] In a possible implementation, the transmission beam of message 2 corresponds to the first preamble, or the transmission beam of message 2 corresponds to the time-frequency resource of the first preamble. The transmission beam of message 2 is the same as the transmission beam of the first SSB.

[0158] In another possible implementation, the transmission beam of message 2 may be measured randomly by the first access network device instead, or the RSRP of the reception beam corresponding to the transmission beam of message 2 is greater than or equal to a threshold.

[0159] 403: The terminal device transmits a message 3 (MSG3) to the first access network device.

[0160] Message 3 includes an RRC resume request and first uplink data.

[0161] The transmission beam of Message 3 is the same as the transmission beam of Message 1. The reception beam of Message 3 is the same as the reception beam of Message 1.

[0162] 404: The first access network device transmits a Message 4 (MSG4) to the terminal device.

[0163] MSG4 may also be referred to as a collision resolution message. The reception beam of Message 4 is the same as the reception beam of Message 2. The transmission beam of Message 4 is the same as the transmission beam of Message 2.

[0164] After receiving Message 4, the terminal device determines that the first Temporary C-RNTI is the C-RNTI of the terminal device. The C-RNTI of the terminal device is used to identify the terminal device.

[0165] After the first random access is successful, the terminal device may further transmit HARQ feedback for Message 4 to the first access network device. The transmission beam of the HARQ feedback is the same as the transmission beam of Message 1 or Message 3. The reception beam of the HARQ feedback is the same as the reception beam of Message 1 or Message 3.

[0166] FIG. 5 is another schematic flowchart of a first random access according to an embodiment of the present application. As shown in FIG. 5, the first random access includes the following steps 501 and 502.

[0167] 501: The terminal device transmits a Message A (MSGA) to the first access network device.

[0168] Message A includes a first preamble, an RRC recovery request, and first uplink data. That is, Message A includes the contents of Message 1 and Message 2 of the four-step random access.

[0169] Similarly, the first access network device periodically transmits SSBs. The first access network device transmits a plurality of SSBs in each period. There is a correspondence between each SSB of the plurality of SSBs and a random access time-frequency resource (that is, the time-frequency resource corresponding to the preamble) or the preamble. The terminal device measures the plurality of SSBs to determine a first SSB from the plurality of SSBs, and the reference signal received power (RSRP) of the first SSB is greater than or equal to a threshold value. The first preamble corresponds to the first SSB, or the time-frequency resource of the first preamble corresponds to the first SSB.

[0170] The transmission beam of Message A is measured by the terminal device. For example, the transmission beam of Message A may be randomly measured by the terminal device, or the RSRP of the reception beam corresponding to the transmission beam of Message A is greater than or equal to a threshold value.

[0171] The reception beam of Message A is measured by the first access network device. For example, the reception beam of Message A may be randomly measured by the first access network device, or the RSRP of the reception beam of Message A is greater than or equal to a threshold value.

[0172] 502: The first access network device transmits a Message B (MSGB) to the terminal device.

[0173] The MSGB includes a fallback RAR (fallbackRAR) or a success RAR (successRAR). The fallback RAR includes a first Temporary C-RNTI, a TA command, and a UL grant. The success RAR includes a first C-RNTI, collision resolution, a TA command, a Hybrid Automatic Repeat reQuest feedback timing indicator (HARQ feedback timing indicator), and a Physical Uplink Control Channel resource indicator (PUCCH resource indicator).

[0174] If the first access network device successfully decodes the first preamble but fails to decode the RRC recovery request and the first uplink data, the first access network device sends a fallback RAR to the terminal device. The terminal device transmits scheduling of transmission to the first access network device based on the fallback RAR, which is similar to sending Message 3 in the above four-step random access. Then, the terminal device receives a collision resolution message from the first access network device, which is similar to receiving Message 4 in the above four-step random access. After receiving the collision resolution message, the terminal device determines that the first Temporary C-RNTI is the C-RNTI of the terminal device, and the first random access is completed.

[0175] If the first access network device successfully decodes the first preamble, the RRC recovery request, and the first uplink data, the first access network device sends a success RAR to the terminal device. The terminal device determines that the first C-RNTI of the success RAR is the C-RNTI of the terminal device, and the first random access process is completed.

[0176] In a possible implementation example, the reception beam of message B corresponds to the first preamble, or the reception beam of message B corresponds to the time-frequency resource of the first preamble. The reception beam of message B is the same as the reception beam of the first SSB.

[0177] In a possible implementation example, the transmission beam of message B corresponds to the first preamble, or the transmission beam of message B corresponds to the time-frequency resource of the first preamble. The transmission beam of message B is the same as the transmission beam of the first SSB.

[0178] In another possible implementation example, the reception beam used by the terminal device to receive message B may be randomly determined by the terminal device instead, or the reception beam used by the terminal device to receive message B is the reception beam with the maximum RSRP.

[0179] After the first random access is successful, the terminal device may further send HARQ feedback to the first access network device. There are two cases in this example. In the case of a success RAR, the HARQ feedback sent by the terminal device is the HARQ feedback of the success RAR. The HARQ feedback resource is indicated by the HARQ feedback timing indicator of the success RAR and the PUCCH resource indicator. The HARQ feedback timing indicator indicates a time-domain resource, and the PUCCH resource indicator indicates a frequency-domain resource. In the case of a fallback RAR, the HARQ feedback sent by the terminal device is the collision resolution HARQ feedback. The transmission beam of the HARQ feedback is the same as the transmission beam of message A. The reception beam of the HARQ feedback is the same as the reception beam of message A.

[0180] FIG. 6 is a schematic flowchart of another communication method according to an embodiment of the present application. As shown in FIG. 6, the communication method includes the following step 601.

[0181] 601: In the radio resource control inactive (RRC inactive) state, the terminal device transmits an RRC recovery request and first uplink data to a first access network device through a first configured grant (CG) resource using a first transmission beam, where the first transmission beam is the same as the transmission beam of the terminal device in the RRC connected state, or the first transmission beam is the same as the transmission beam of the previous data transmission process when the terminal device was in the RRC inactive state.

[0182] Correspondingly, the first access network device may receive the RRC recovery request and the first uplink data transmitted by the terminal device using a second reception beam. The second reception beam is the same as the reception beam used by the first access network device to receive the uplink transmission of the terminal device in the RRC connected state, or the second reception beam is the same as the reception beam used by the first access network device to receive the uplink transmission of the terminal device in the RRC inactive state in the previous data transmission process.

[0183] The current data transmission process is a CG data transmission process. If the current data transmission process is the first data transmission process after the terminal device enters the RRC inactive state, the first transmission beam is the same as the transmission beam of the terminal device in the RRC connected state. If the current data transmission process is not the first data transmission process after the terminal device enters the RRC inactive state, the first transmission beam is the same as the transmission beam of the previous data transmission process when the terminal device was in the RRC inactive state. The previous data transmission process may be either a CG data transmission process or a random access (RA) data transmission process.

[0184] If the current data transmission process is the first data transmission process after the terminal device enters the RRC inactive state, the second receiving beam is the same as the receiving beam used by the first access network device to receive the uplink transmission of the terminal device in the RRC connected state. If the current data transmission process is not the first data transmission process after the terminal device enters the RRC inactive state, the second receiving beam is the same as the receiving beam used by the first access network device to receive the uplink transmission of the terminal device in the RRC inactive state in the previous data transmission process.

[0185] In a possible implementation example, the fact that the first transmission beam is the same as the transmission beam of the terminal device in the RRC connected state means that the first transmission beam is the same as the transmission beam finally used by the terminal device in the RRC connected state, or the first transmission beam is the same as the last indicated transmission beam when the terminal device is in the RRC connected state, or the first transmission beam is the same as the last transmission beam determined by the terminal device in the RRC connected state, or the first transmission beam is the same as the transmission beam finally used by the terminal device to transmit PUCCH, PUSCH or SRS when the terminal device is in the RRC connected state, or the first transmission beam is the same as the last indicated transmission beam used to transmit PUCCH, PUSCH or SRS when the terminal device is in the RRC connected state, or the first transmission beam is the same as the last transmission beam determined by the terminal device in the RRC connected state and used to transmit PUCCH, PUSCH or SRS.

[0186] In a possible implementation example, the fact that the first transmission beam is the same as the transmission beam of the previous data transmission process when the terminal device was in the RRC inactive state means that the first transmission beam is the same as the transmission beam finally used in the previous data transmission process when the terminal device was in the RRC inactive state, or the first transmission beam is the same as the last transmission beam determined in the previous data transmission process when the terminal device was in the RRC inactive state.

[0187] In a possible implementation example, the fact that the second reception beam is the same as the reception beam used by the first access network device to receive the uplink transmission of the terminal device in the RRC connected state means that the second reception beam is the same as the reception beam finally used by the first access network device to receive the uplink transmission of the terminal device in the RRC connected state, or the second reception beam is the same as the reception beam finally used by the first access network device to receive the PUCCH, PUSCH or SRS transmitted by the terminal device in the RRC connected state.

[0188] In a possible implementation example, the fact that the second reception beam is the same as the reception beam used by the first access network device to receive the uplink transmission of the terminal device in the RRC inactive state in the previous data transmission process means that the second reception beam is the same as the reception beam finally used by the first access network device to receive the uplink transmission of the terminal device in the RRC inactive state in the previous data transmission process.

[0189] Based on the method described in FIG. 6, it can be found that the terminal device performs the current transmission in the RRC inactive state using the beam transmitted previously. In this way, the terminal device does not need to perform a series of operations such as beam measurement and measurement result reporting to determine the beam, thereby reducing the power consumption of the terminal device.

[0190] FIG. 7 is a schematic flowchart of another communication method according to an embodiment of the present application. As shown in FIG. 7, the communication method includes the following steps 701 to 703. The specific implementation of step 701 is the same as the implementation of step 601 in FIG. 6. Details will not be described repeatedly in this description.

[0191] 701: In the radio resource control inactive (RRC inactive) state, the terminal device transmits an RRC recovery request and first uplink data to the first access network device through the first CG resource using the first transmission beam, and the first transmission beam is the same as the transmission beam of the terminal device in the RRC connected state, or the first transmission beam is the same as the transmission beam in the previous data transmission process when the terminal device was in the RRC inactive state.

[0192] 702: The first access network device transmits a first response transmitted in response to the RRC recovery request and the first uplink data to the terminal device.

[0193] In the present embodiment of the present application, after receiving the RRC recovery request and the first uplink data transmitted by the terminal device, the first access network device transmits a first response transmitted in response to the RRC recovery request and the first uplink data to the terminal device.

[0194] In a possible implementation example, the first response may be a HARQ feedback, a dynamic grant (DG), or an RRC release message.

[0195] HARQ feedback includes NACK (Negative Acknowledgment) or ACK (Positive Acknowledgment). NACK indicates that the first access network device fails to obtain the RRC recovery request and the first uplink data through decoding, and ACK indicates that the first access network device successfully obtains the RRC recovery request and the first uplink data through decoding. When the first response is HARQ feedback, refer to the descriptions in FIGS. 8 and 9 for the operations of the terminal device after receiving the first response. Details are not described in this description.

[0196] DG may include indication information 1 used to indicate (1) retransmission or new transmission, for example, NDI (New data indicator) = 0 indicates retransmission or non-inverted NDI indicates retransmission, NDI = 1 indicates new transmission or inverted NDI indicates new transmission, indication information 2 used to indicate the time-frequency resource of retransmission or new transmission, and indication information 3 used to indicate the modulation and coding scheme (MCS) used for retransmission or new transmission. When the first response is DG, refer to the descriptions in FIGS. 10 and 11 for the operations of the terminal device after receiving the first response. Details are not described in this description.

[0197] When the first response is an RRC release message, the terminal device terminates the current CG data transmission process.

[0198] The first access network device may transmit a first response transmitted for the RRC recovery request and the first uplink data to the terminal device using a second transmission beam. The second transmission beam is the same as the transmission beam used by the first access network device to transmit downlink transmissions to the terminal device in the RRC connected state, or the second transmission beam is the same as the transmission beam used by the first access network device to transmit downlink transmissions to the terminal device in the RRC inactive state in a previous data transmission process. The second transmission beam is a transmission beam related to the first CG resource.

[0199] If the current data transmission process is the first data transmission process after the terminal device enters the RRC inactive state, the second transmission beam is the same as the transmission beam used by the first access network device to transmit downlink transmissions to the terminal device in the RRC connected state, or the second transmission beam is a transmission beam related to the first CG resource. If the current data transmission process is not the first data transmission process after the terminal device enters the RRC inactive state, the second transmission beam is the same as the transmission beam used by the first access network device to transmit downlink transmissions to the terminal device in the RRC inactive state in a previous data transmission process, or the second transmission beam is a transmission beam related to the first CG resource.

[0200] In a possible implementation, the fact that the second transmission beam is the same as the transmission beam used by the first access network device to transmit downlink transmissions to the terminal device in the RRC connected state means that the second transmission beam is the same as the transmission beam finally used by the first access network device to transmit downlink transmissions to the terminal device in the RRC connected state, or the second transmission beam is the same as the transmission beam finally used by the first access network device to transmit PDCCH or PDSCH to the terminal device in the RRC connected state.

[0201] In a possible implementation example, the fact that the second transmission beam is the same as the transmission beam used by the first access network device to transmit downlink transmission to a terminal device in the RRC inactive state in a previous data transmission process means that the second transmission beam is the same as the transmission beam finally used by the first access network device to transmit downlink transmission to a terminal device in the RRC inactive state in a previous data transmission process.

[0202] 703: The terminal device receives, using a first reception beam, a first response transmitted by the first access network device for an RRC recovery request and first uplink data, where the first reception beam is the same as the reception beam of the terminal device in the RRC connected state, or the first reception beam is the same as the reception beam of a previous data transmission process in which the terminal device was in the RRC inactive state, or the first reception beam is a reception beam associated with a first CG resource.

[0203] If the current data transmission process is the first data transmission process after the terminal device enters the RRC inactive state, the first reception beam is the same as the reception beam of the terminal device in the RRC connected state, or the first reception beam is a reception beam associated with a first CG resource. If the current data transmission process is not the first data transmission process after the terminal device enters the RRC inactive state, the first reception beam is the same as the reception beam of a previous data transmission process in which the terminal device was in the RRC inactive state, or the first reception beam is a reception beam associated with a first CG resource.

[0204] In a possible implementation example, the fact that the first receiving beam is the same as the receiving beam of a terminal device in the RRC connected state means that the first receiving beam is the same as the receiving beam finally used by the terminal device in the RRC connected state, or when the terminal device is in the RRC connected state, the first receiving beam is the same as the last indicated receiving beam, or the first receiving beam is the same as the last receiving beam determined by the terminal device in the RRC connected state, or when the terminal device is in the RRC connected state, the first receiving beam is the same as the receiving beam finally used by the terminal device to transmit the PDCCH or PDSCH, or when the terminal device is in the RRC connected state, the first receiving beam is the same as the last indicated receiving beam used to transmit the PDCCH or PDSCH, or the first receiving beam is the same as the last receiving beam determined by the terminal device in the RRC connected state and used to transmit the PDCCH or PDSCH.

[0205] In a possible implementation example, the fact that the first receiving beam is the same as the receiving beam of a previous data transmission process when the terminal device was in the RRC inactive state means that the first receiving beam is the same as the receiving beam finally used in the previous data transmission process when the terminal device was in the RRC inactive state, or the first receiving beam is the same as the last receiving beam determined in the previous data transmission process when the terminal device was in the RRC inactive state.

[0206] In a possible implementation example, the terminal device may further monitor a PDCCH corresponding to a C-RNTI or a configured scheduling radio network temporary identifier (CS-RNTI). The PDCCH may carry a first response or carry a DCI indicating a transmission resource of the first response. The PDCCH corresponding to the C-RNTI is a PDCCH scrambled by the C-RNTI. The PDCCH corresponding to the CS-RNTI of the terminal device is a PDCCH scrambled by the CS-RNTI of the terminal device.

[0207] When the first response is a DG, the PDCCH corresponding to the CS-RNTI of the terminal device carries the first response. When the first response is a HARQ feedback for an RRC recovery request or an RRC release message, the PDCCH corresponding to the C-RNTI carries a DCI indicating a transmission resource of the first response. In this way, after monitoring the PDCCH, the terminal device can receive a DCI on the PDCCH and can receive the first response based on the transmission resource indicated by the DCI, which is the transmission resource of the first response.

[0208] In a possible implementation example, when the first condition is satisfied, the terminal device stops monitoring the PDCCH corresponding to the C-RNTI or CS-RNTI. The first condition includes any one of the conditions that a beam failure occurs and a timer expires. The timer is used to control the terminal device to monitor the PDCCH of the C-RNTI or CS-RNTI, or the timer is used to control the validity of the transmission beam. The beam failure includes that the reference signal received power (RSRP) of the first received beam is less than the first threshold, or the consecutive N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2, or within the first time period, the consecutive N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2, or the reference signal received power (RSRP) of the received beam corresponding to the first transmission beam is less than the second threshold, or the consecutive N RSRPs of the received beam corresponding to the first transmission beam are less than the second threshold, where N is an integer greater than or equal to 2, or within the first time period, the consecutive N RSRPs of the received beam corresponding to the first transmission beam are less than the second threshold, where N is an integer greater than or equal to 2. Based on this possible implementation example, when a beam failure occurs in the first received beam or the probability that the signal reception quality of the first received beam has already deteriorated is high, it is possible to timely stop monitoring the PDCCH corresponding to the C-RNTI or CS-RNTI in order to reduce the power consumption of the terminal device. Instead, based on this possible implementation example, when a beam failure occurs in the first transmission beam or the first transmission beam is invalid, it is possible to timely stop monitoring the PDCCH corresponding to the C-RNTI or CS-RNTI, thereby reducing the power consumption of the terminal device.

[0209] In a possible implementation example, when the first condition is satisfied, the terminal device performs random access. After the random access is completed, the terminal device may perform transmission using a beam that is the same as the beam of the random access. For example, the terminal device may perform downlink transmission using a beam that is the same as the receiving beam of the random access, or may perform uplink transmission using a beam that is the same as the transmitting beam of the random access. Therefore, when the above first condition is satisfied, the terminal device can update the beam in time by performing random access.

[0210] In a possible implementation example, when the terminal device receives a DG, a timer is started or restarted. Instead, when the terminal device performs data transmission based on a CG resource, a timer is started or restarted.

[0211] In a possible implementation example, the random access is a four-step random access. The message 3 of the random access carries a C-RNTI. The PDCCH of the message 4 of the random access is scrambled by the C-RNTI. Based on this possible implementation example, after the random access is performed, the C-RNTI does not change every time. In this way, the first access network device may transmit the C-RNTI to the second access network device only once. In this way, it is possible to avoid the potential risk of security inconsistency, and it is possible to reduce the signaling handover between the two access network devices.

[0212] In a possible implementation example, the random access is two-step random access. The random access message A includes a C-RNTI, and the PDCCH of the random access message B is scrambled by the C-RNTI. Based on this possible implementation example, after the random access is performed, the C-RNTI does not change every time. In this way, the first access network device may send the C-RNTI to the second access network device only once. In this way, it is possible to avoid the potential risk of security inconsistency, and it is possible to reduce the signaling handover between the two access network devices.

[0213] Based on the method described in FIG. 7, it can be found that the receiving beam used by the terminal device to receive the RRC recovery request and the first response to the first uplink data in the RRC inactive state is determined. In this way, it is not necessary for the terminal device to perform a series of operations such as beam measurement and measurement result reporting to determine the receiving beam used to receive the first response, thereby reducing the power consumption of the terminal device.

[0214] FIG. 8 is a schematic flowchart of another communication method according to an embodiment of the present application. As shown in FIG. 8, the communication method includes the following steps 801 to 804. The specific implementation of step 801 is the same as the implementation of step 601 in FIG. 6. Details will not be described repeatedly in this description.

[0215] 801: In the radio resource control inactive (RRC inactive) state, the terminal device transmits an RRC recovery request and first uplink data to the first access network device through a first CG resource using a first transmission beam, where the first transmission beam is the same as the transmission beam of the terminal device in the RRC connected state, or the first transmission beam is the same as the transmission beam of the previous data transmission process when the terminal device was in the RRC inactive state.

[0216] 802: The first access network device transmits a negative acknowledgment NACK sent for the RRC recovery request and the first uplink data to the terminal device.

[0217] 803: The terminal device receives, using a first reception beam, the NACK transmitted by the first access network device for the RRC recovery request and the first uplink data, where the first reception beam is the same as the reception beam of the terminal device in the RRC connected state, or the first reception beam is the same as the reception beam of a previous data transmission process when the terminal device was in the RRC inactive state, or the first reception beam is a reception beam associated with the first CG resource.

[0218] 804: The terminal device re - transmits the RRC recovery request and the first uplink data to the first access network device through a second CG resource, and the transmission beam for re - transmitting the RRC recovery request and the first uplink data is the same as the transmission beam of the previous uplink transmission.

[0219] In one example, if the previous uplink transmission of the terminal device is step 801, the transmission beam for re - transmitting the RRC recovery request and the first uplink data is the same as the first transmission beam. In another example, after receiving the NACK, the terminal device recognizes that a beam failure has occurred in the first transmission beam, and the terminal device performs random access to update the beam of the terminal device. In this case, the transmission beam for re - transmitting the RRC recovery request and the first uplink data is the same as the transmission beam used by the terminal device for performing random access.

[0220] Correspondingly, the first access network device may receive the RRC recovery request and the first uplink data retransmitted by the terminal device. The reception beam used for the RRC recovery request and the first uplink data is the same as the reception beam used in the previous uplink transmission. For example, the reception beam used by the first access network device in the previous uplink transmission is the second reception beam. Alternatively, the reception beam used by the first access network device in the previous uplink transmission is the same as the reception beam used in the random access process.

[0221] In a possible implementation example, by default, the terminal device uses the same beam as the transmission beam of the previous uplink transmission, and the RRC recovery request and the first uplink data are the first retransmitted to the access network device through the second CG resource. Correspondingly, by default, the first access network device uses the same beam as the reception beam used in the previous uplink transmission, and may instead receive the RRC recovery request and the first uplink data retransmitted by the terminal device.

[0222] Alternatively, the first access network device may send indication information to the terminal device. Correspondingly, the terminal device receives the indication information sent by the first access network device. If the indication information indicates that the same beam as the transmission beam of the previous uplink transmission is used for uplink transmission, the transmission beam for retransmitting the RRC recovery request and the first uplink data is the same as the transmission beam of the previous uplink transmission. Correspondingly, the reception beam for retransmitting the RRC recovery request and the first uplink data is the same as the reception beam used in the previous uplink transmission.

[0223] When the indication information indicates that a beam that is the same as the transmission beam of the previous uplink transmission is not used for the uplink transmission, the transmission beam for retransmitting the RRC recovery request and the first uplink data is different from the transmission beam of the previous uplink transmission. Correspondingly, the reception beam for retransmitting the RRC recovery request and the first uplink data is different from the reception beam used in the previous uplink transmission.

[0224] Instead, by default, the terminal device does not use a beam that is the same as the transmission beam of the previous uplink transmission, and the RRC recovery request and the first uplink data may be retransmitted to the access network device through the second CG resource. By default, the first access network device does not use a beam that is the same as the reception beam used in the previous uplink transmission, and the RRC recovery request and the first uplink data retransmitted by the terminal device may be received instead.

[0225] Based on the method described in FIG. 8, it can be found that the reception beam used by the terminal device to retransmit the RRC recovery request and the first uplink data in the RRC inactive state is determined. In this way, it is not necessary for the terminal device to perform a series of operations such as beam measurement and measurement result reporting to determine the transmission beam used to retransmit the RRC recovery request and the first uplink data. This promotes reducing the power consumption of the terminal device.

[0226] FIG. 9 is a schematic flowchart of another communication method according to an embodiment of the present application. As shown in FIG. 9, the communication method includes the following steps 901 to 904. The specific implementation of step 901 is the same as the implementation of step 601 in FIG. 6. Details will not be described repeatedly in this description.

[0227] 901: In the Radio Resource Control Inactive (RRC Inactive) state, the terminal device transmits an RRC recovery request and first uplink data to a first access network device through a first Configured Grant (CG) resource using a first transmission beam. The first transmission beam is the same as the transmission beam of the terminal device in the RRC connected state, or the first transmission beam is the same as the transmission beam of the previous data transmission process when the terminal device was in the RRC Inactive state.

[0228] 902: The first access network device transmits an ACK transmitted for the RRC recovery request and the first uplink data to the terminal device.

[0229] 903: The terminal device receives the ACK transmitted by the first access network device for the RRC recovery request and the first uplink data using a first reception beam. The first reception beam is the same as the reception beam of the terminal device in the RRC connected state, or the first reception beam is the same as the reception beam of the previous data transmission process when the terminal device was in the RRC Inactive state, or the first reception beam is the reception beam associated with the first CG resource.

[0230] 904: The terminal device transmits second uplink data to the first access network device through a second CG resource. The transmission beam of the second uplink data is the same as the transmission beam of the previous uplink transmission, and the second uplink data is different from the first uplink data.

[0231] The terminal device transmits second uplink data different from the first uplink data to the access network device, that is, the terminal device transmits new uplink data to the access network device.

[0232] In one example, when the previous uplink transmission of the terminal device is step 901, the transmission beam of the second uplink data is the same as the first transmission beam. In another example, after receiving the ACK, the terminal device recognizes that a beam failure has occurred in the first transmission beam, and the terminal device performs random access to update the beam of the terminal device. In this case, the transmission beam of the second uplink data is the same as the transmission beam used by the terminal device to perform random access.

[0233] Correspondingly, the first access network device receives the second uplink data transmitted by the terminal device. The reception beam of the second uplink data is the same as the reception beam used in the previous uplink transmission. For example, the reception beam used by the first access network device in the previous uplink transmission is the second reception beam. Alternatively, the reception beam used by the first access network device in the previous uplink transmission is the same as the reception beam used in the random access process.

[0234] In a possible implementation example, by default, the terminal device uses a beam that is the same as the transmission beam of the previous uplink transmission, and the second uplink data may be transmitted to the access network device through the second CG resource. Correspondingly, by default, the first access network device uses a beam that is the same as the reception beam used in the previous uplink transmission, and the second uplink data transmitted by the terminal device may be received instead.

[0235] Alternatively, the first access network device may transmit indication information to the terminal device. Correspondingly, the terminal device receives the indication information transmitted by the first access network device. When the indication information indicates that a beam that is the same as the transmission beam of the previous uplink transmission is used for the uplink transmission, the transmission beam of the second uplink data is the same as the transmission beam of the previous uplink transmission. The reception beam of the second uplink data is the same as the reception beam used in the previous uplink transmission.

[0236] When the indication information indicates that a beam that is the same as the transmission beam of the previous uplink transmission is not used for the uplink transmission, the transmission beam of the second uplink data is different from the transmission beam of the previous uplink transmission. The reception beam of the second uplink data is different from the reception beam used in the previous uplink transmission.

[0237] Alternatively, by default, the terminal device does not use a beam that is the same as the transmission beam of the previous uplink transmission, and the second uplink data may be transmitted to the access network device through the second CG resource. By default, the first access network device does not use a reception beam that is the same as the reception beam used in the previous uplink transmission, and the second uplink data transmitted by the terminal device may be received instead.

[0238] Based on the method described in FIG. 9, it can be found that the reception beam used by the terminal device for transmitting the second uplink data in the RRC inactive state is determined. In this way, it is not necessary for the terminal device to perform a series of operations such as beam measurement and measurement result reporting to determine the transmission beam for transmitting the second uplink data. This promotes reducing the power consumption of the terminal device.

[0239] FIG. 10 is a schematic flowchart of another communication method according to an embodiment of the present application. As shown in FIG. 10, the communication method includes the following steps 1001 to 1004. The specific implementation of step 1001 is the same as the implementation of step 601 in FIG. 6. Details will not be repeated in this description.

[0240] 1001: In the radio resource control inactive (RRC inactive) state, the terminal device transmits an RRC recovery request and first uplink data to a first access network device through a first configured grant (CG) resource using a first transmission beam. The first transmission beam is the same as the transmission beam of the terminal device in the RRC connected state, or the first transmission beam is the same as the transmission beam in the previous data transmission process when the terminal device was in the RRC inactive state.

[0241] 1002: The first access network device transmits a dynamic grant (DG) for the RRC recovery request and the first uplink data to the terminal device, where the DG indicates retransmission.

[0242] 1003: The terminal device receives the DG transmitted by the first access network device for the RRC recovery request and the first uplink data using a first reception beam. The first reception beam is the same as the reception beam of the terminal device in the RRC connected state, or the first reception beam is the same as the reception beam in the previous data transmission process when the terminal device was in the RRC inactive state, or the first reception beam is the reception beam associated with the first CG resource.

[0243] 1004: The terminal device retransmits the RRC recovery request and the first uplink data to the first access network device, and the transmission beam for retransmitting the RRC recovery request and the first uplink data is the same as the transmission beam in the previous uplink transmission.

[0244] In one example, when the previous uplink transmission of the terminal device is step 1001, the RRC recovery request and the transmission beam for retransmitting the first uplink data are the same as the first transmission beam. In another example, after receiving the DG indicating retransmission, the terminal device recognizes that a beam failure has occurred in the first transmission beam, and the terminal device performs random access to update the beam of the terminal device. In this case, the RRC recovery request and the transmission beam for retransmitting the first uplink data are the same as the transmission beam used by the terminal device for performing random access.

[0245] Correspondingly, the first access network device may receive the RRC recovery request and the first uplink data retransmitted by the terminal device. The reception beam used for the RRC recovery request and the first uplink data is the same as the reception beam used in the previous uplink transmission. For example, the reception beam used by the first access network device in the previous uplink transmission is the second reception beam. Alternatively, the reception beam used by the first access network device in the previous uplink transmission is the same as the reception beam used in the random access process.

[0246] In a possible implementation example, by default, the terminal device uses the same beam as the transmission beam of the previous uplink transmission to retransmit the RRC recovery request and the first uplink data to the access network device. Correspondingly, by default, the first access network device uses the same beam as the reception beam used in the previous uplink transmission to receive the RRC recovery request and the first uplink data retransmitted by the terminal device instead.

[0247] Alternatively, the first access network device may send the indication information to the terminal device. Correspondingly, the terminal device receives the indication information sent by the first access network device. When the indication information indicates that a beam that is the same as the transmission beam of the previous uplink transmission is used for the uplink transmission, the transmission beam for retransmitting the RRC recovery request and the first uplink data is the same as the transmission beam of the previous uplink transmission. Correspondingly, the reception beam for retransmitting the RRC recovery request and the first uplink data is the same as the reception beam used in the previous uplink transmission.

[0248] When the indication information indicates that a beam that is the same as the transmission beam of the previous uplink transmission is not used for the uplink transmission, the transmission beam for retransmitting the RRC recovery request and the first uplink data is different from the transmission beam of the previous uplink transmission. Correspondingly, the reception beam for retransmitting the RRC recovery request and the first uplink data is different from the reception beam used in the previous uplink transmission.

[0249] Alternatively, by default, the terminal device does not use a beam that is the same as the transmission beam of the previous uplink transmission, and the RRC recovery request and the first uplink data may be retransmitted to the access network device. By default, the first access network device does not use a reception beam that is the same as the reception beam used in the previous uplink transmission, and the RRC recovery request and the first uplink data retransmitted by the terminal device may be received instead.

[0250] Based on the method described in FIG. 10, it can be found that the reception beam used by the terminal device to retransmit the RRC recovery request and the first uplink data in the RRC inactive state is determined. In this way, it is not necessary for the terminal device to perform a series of operations such as beam measurement and measurement result reporting to determine the transmission beam used to retransmit the RRC recovery request and the first uplink data. This promotes reducing the power consumption of the terminal device.

[0251] FIG. 11 is a schematic flowchart of another communication method according to an embodiment of the present application. As shown in FIG. 11, the communication method includes the following steps 1101 to 1104. The specific implementation of step 1101 is the same as the implementation of step 601 in FIG. 6. Details will not be described repeatedly in this description.

[0252] 1101: In the radio resource control inactive (RRC inactive) state, the terminal device transmits an RRC recovery request and first uplink data to a first access network device through a first configured grant (CG) resource using a first transmission beam, where the first transmission beam is the same as the transmission beam of the terminal device in the RRC connected state, or the first transmission beam is the same as the transmission beam in the previous data transmission process when the terminal device was in the RRC inactive state.

[0253] 1102: The first access network device may further transmit a dynamic grant (DG) for the RRC recovery request and the first uplink data to the terminal device, where the DG indicates a new transmission.

[0254] 1103: The terminal device receives the DG transmitted by the first access network device for the RRC recovery request and the first uplink data using a first reception beam, where the first reception beam is the same as the reception beam of the terminal device in the RRC connected state, or the first reception beam is the same as the reception beam in the previous data transmission process when the terminal device was in the RRC inactive state, or the first reception beam is a reception beam associated with the first CG resource.

[0255] 1104: The terminal device transmits second uplink data to the first access network device, where the transmission beam of the second uplink data is the same as the transmission beam of the previous uplink transmission, and the second uplink data is different from the first uplink data.

[0256] Second uplink of the data The transmission beam is the same as the transmission beam of the previous uplink transmission. In one example, if the previous uplink transmission of the terminal device is step 1101, the transmission beam of the second uplink data is the same as the first transmission beam. In another example, after receiving a DG indicating a new transmission, the terminal device recognizes that a beam defect has occurred in the first transmission beam, and the terminal device performs random access to update the beam of the terminal device. In this case, the transmission beam of the second uplink data is the same as the transmission beam used by the terminal device to perform random access.

[0257] Correspondingly, the first access network device receives the second uplink data transmitted by the terminal device. The reception beam of the second uplink data is the same as the reception beam used in the previous uplink transmission. For example, the reception beam used by the first access network device in the previous uplink transmission is the second reception beam. Alternatively, the reception beam used by the first access network device in the previous uplink transmission is the same as the reception beam used in the random access process.

[0258] In a possible implementation example, by default, the terminal device may transmit the second uplink data to the access network device using a beam that is the same as the transmission beam of the previous uplink transmission. Correspondingly, by default, the first access network device may receive the second uplink data transmitted by the terminal device using a beam that is the same as the reception beam used in the previous uplink transmission.

[0259] Alternatively, the first access network device may send the indication information to the terminal device. Correspondingly, the terminal device receives the indication information sent by the first access network device. When the indication information indicates that a beam that is the same as the transmission beam of the previous uplink transmission is used for the uplink transmission, the transmission beam of the second uplink data is the same as the transmission beam of the previous uplink transmission. The reception beam of the second uplink data is the same as the reception beam used in the previous uplink transmission.

[0260] When the indication information indicates that a beam that is the same as the transmission beam of the previous uplink transmission is not used for the uplink transmission, the transmission beam of the second uplink data is different from the transmission beam of the previous uplink transmission. The reception beam of the second uplink data is different from the reception beam used in the previous uplink transmission.

[0261] Alternatively, by default, the terminal device does not use a beam that is the same as the transmission beam of the previous uplink transmission, and the second uplink data may be sent to the access network device. By default, the first access network device does not use a reception beam that is the same as the reception beam used in the previous uplink transmission, and the first access network device may alternatively receive the second uplink data sent by the terminal device.

[0262] Based on the method described in FIG. 11, it can be found that the reception beam used by the terminal device for transmitting the second uplink data in the RRC inactive state is determined. In this way, it is not necessary for the terminal device to perform a series of operations such as beam measurement and measurement result reporting to determine the transmission beam for transmitting the second uplink data. This promotes reducing the power consumption of the terminal device.

[0263] FIG. 12 is a schematic flowchart of another communication method according to an embodiment of the present application. As shown in FIG. 12, the communication method includes the following steps 1201 to 1204.

[0264] 1201: A terminal device in the Radio Resource Control Inactive (RRC Inactive) state sends a second message 1 to a network device, and the second message 1 includes a second preamble. the first The second message 1 is sent to the network device, and the second message 1 includes a second preamble.

[0265] 1202: A first access network device sends a second message 2 to the terminal device, and the second message 2 includes a second Temporary C-RNTI.

[0266] In the present embodiment of the present application, after receiving the second message 1 sent by the terminal device, the first access network device sends the second message 2 to the terminal device.

[0267] Optionally, the second Temporary C-RNTI is used for rescheduling the retransmission of the second MSG3.

[0268] In the present embodiment of the present application, the first access network device does not send the second Temporary C-RNTI to the second access network device (i.e., the last serving gNB).

[0269] 1203: The terminal device sends a second message 3 to the first access network device, and the second message 3 includes the C-RNTI of the terminal device.

[0270] In the present embodiment of the present application, after receiving the second message 2, the terminal device sends the second message 3 to the first access network device.

[0271] In the present embodiment of the present application, the second message 3 does not include an RRC recovery request.

[0272] 1204: The first access network device sends a second message 4 to the terminal device, and the PDCCH of the second message 4 is scrambled by the C-RNTI of the terminal device.

[0273] In the present embodiment of the present application, after receiving the second message 3, the first access network device uses the C-RNTI of the terminal device, which is the C-RNTI carried in the second message 3, to scramble the PDCCH of the second message 4, and then transmits the second message 4 to the terminal device.

[0274] In the method described in FIG. 12, instead of using the second Temporary C-RNTI to scramble the PDCCH of the second message 4, the C-RNTI of the terminal device can be used to scramble the PDCCH of the second message 4. The C-RNTI of the terminal device remains unchanged during one data transmission process. In this way, the first access network device may transmit the C-RNTI to the second access network device only once. In this way, it is possible to avoid the potential risk of the security inconsistency described above, and it is possible to reduce the signaling handover between the two access network devices.

[0275] FIGS. 13A and 13B are schematic flowcharts of another communication method according to an embodiment of the present application. As shown in FIGS. 13A and 13B, the communication method includes the following steps 1301 to 1310.

[0276] 1301: A radio resource control inactive (RRC inactive) state terminal device transmits a first message 1 to a first access network device, and the first message 1 includes a first preamble.

[0277] 1302: The first access network device transmits a first message 2 to the terminal device, and the first message 2 includes a first Temporary C-RNTI.

[0278] In this embodiment of the present application, after receiving the first message 1, the first access network device transmits the first message 2 to the terminal device.

[0279] In this embodiment of the present application, the first message 2 may further include an uplink grant (UL grant), a timing advance command (TA command), etc.

[0280] 1303: The terminal device transmits the first message 3 to the first access network device, and the first message 3 includes an RRC recovery request and the first uplink data.

[0281] In this embodiment of the present application, after receiving the first message 2, the terminal device transmits the first message 3 to the first access network device.

[0282] 1304: The first access network device transmits the first message 4 to the terminal device.

[0283] The first message 4 includes some contents of the first message 3 and is used for collision resolution.

[0284] In this embodiment of the present application, after receiving the first message 3, the first access network device transmits the first message 4 to the terminal device.

[0285] 1305: The first access network device transmits the first Temporary C-RNTI to the second access network device.

[0286] In the present embodiment of the present application, after the first access network device transmits the first message 4 to the terminal device, the first Temporary C-RNTI is transmitted to the second access network device. After receiving the first Temporary C-RNTI, the second access network device may use the first Temporary C-RNTI to perform identity verification on the terminal device in the next data transmission process.

[0287] 1306: The terminal device determines that the first Temporary C-RNTI is the C-RNTI of the terminal device.

[0288] In the present embodiment of the present application, after receiving the first message 4, the terminal device determines that the first Temporary C-RNTI is the C-RNTI of the terminal device.

[0289] 1307: A terminal device in the Radio Resource Control Inactive (RRC Inactive) state transmits the second message 1 to the access network device, and the second message 1 includes a second preamble.

[0290] 1308: The first access network device transmits the second message 2 to the terminal device, and the second message 2 includes a second Temporary C-RNTI.

[0291] 1309: The terminal device transmits the second message 3 to the first access network device, and the second message 3 includes the C-RNTI of the terminal device.

[0292] 1310: The first access network device transmits the second message 4 to the terminal device, and the PDCCH of the second message 4 is scrambled by the C-RNTI of the terminal device.

[0293] The specific implementation from step 1307 to step 1310 is the same as the implementation from step 1201 to step 1204. Details will not be described repeatedly in this description.

[0294] In the method described in FIGS. 13A and 13B, instead of using the second Temporary C-RNTI to scramble the PDCCH of the second message 4, the C-RNTI of the terminal device can be used to scramble the PDCCH of the second message 4. The C-RNTI of the terminal device in one data transmission process is the first Temporary C-RNTI. In this way, the first access network device may transmit the C-RNTI to the second access network device only once. In this way, it is possible to avoid the potential risk of the security inconsistency described above, and it is possible to reduce the signaling handover between the two access network devices.

[0295] FIG. 14 is a schematic flowchart of a communication method according to an embodiment of the present application. As shown in FIG. 14, the communication method includes the following steps 1401 to 1404.

[0296] 1401: A terminal device in the RRC inactive state transmits a second message A to a first access network device, and the second message A includes a second preamble and the C-RNTI of the terminal device.

[0297] In the present embodiment of the present application, the second message A does not include an RRC recovery request.

[0298] 1402: The first access network device transmits a second message B to the terminal device, and the PDCCH of the second message B is scrambled by the C-RNTI of the terminal device.

[0299] In the present embodiment of the present application, after receiving the second message A, the first access network device scrambles the PDCCH of the second message B using the C-RNTI of the terminal device, which is the C-RNTI carried in the second message A, and then transmits the second message B to the terminal device.

[0300] In the method described in FIG. 14, the first access network device can scramble the PDCCH of the second message B using the C-RNTI of the terminal device. The C-RNTI of the terminal device remains unchanged during one data transmission process. In this way, the first access network device may transmit the C-RNTI to the second access network device only once. In this manner, it is possible to avoid the potential risk of the security inconsistency described above, and it is possible to reduce the signaling transfer between the two access network devices.

[0301] FIG. 15 is a schematic flowchart of a communication method according to an embodiment of the present application. As shown in FIG. 15, the communication method includes the following steps 1501 to 1506.

[0302] 1501: A terminal device in the RRC inactive state transmits a first message A to the first access network device, and the first message A includes a first preamble, an RRC recovery request, and first uplink data.

[0303] 1502: The first access network device transmits a first message B to the terminal device, and the first message B includes a first C-RNTI.

[0304] In the present embodiment of the present application, after receiving the first message A, the first access network device transmits the first message B to the terminal device.

[0305] Optionally, the first message B may further include collision resolution, TA command, hybrid automatic repeat request feedback timing indicator (HARQ feedback timing indicator), and physical uplink control channel resource indicator (PUCCH resource indicator).

[0306] 1503: The first access network device transmits the first C-RNTI to the second access network device.

[0307] In the present embodiment of the present application, after the first access network device transmits the first message B to the terminal device, the first access network device transmits the first C-RNTI to the second access network device. After receiving the first C-RNTI, the second access network device may use the first C-RNTI to perform identity verification on the terminal device in the next data transmission process.

[0308] 1504: The terminal device determines that the first C-RNTI is the C-RNTI of the terminal device.

[0309] In the present embodiment of the present application, after receiving the first message B, the terminal device determines that the first C-RNTI is the C-RNTI of the terminal device, and the random access is completed.

[0310] 1505: The terminal device in the RRC inactive state transmits the second message A to the first access network device, and the second message A includes the second preamble and the C-RNTI of the terminal device.

[0311] 1506: The first access network device transmits the second message B to the terminal device, and the PDCCH of the second message B is scrambled by the C-RNTI of the terminal device.

[0312] The specific implementation from step 1505 to step 1506 is the same as the implementation from step 1501 to step 1506. Details will not be repeatedly described in this description.

[0313] In the method described in FIG. 15, the first access network device can scramble the PDCCH of the second message B using the C-RNTI of the terminal device. The C-RNTI of the terminal device in one data transmission process is the first C-RNTI. In this way, the first access network device may transmit the C-RNTI to the second access network device only once. In this way, it is possible to avoid the potential risk of the security inconsistency described above, and it is possible to reduce the signaling handover between the two access network devices.

[0314] The method provided in this application may be further applied to the scenario of dual connectivity (DC). For ease of understanding, the DC scenario will first be described with reference to FIG. 16 using an example where the terminal device is a UE and the network device is a base station.

[0315] In a wireless network, one UE may communicate with multiple base stations, which may be called dual connectivity (DC), and may also be called multi-radio dual connectivity (MR-DC), and is uniformly expressed as DC hereinafter. The multiple base stations may belong to base stations of the same radio access technology (RAT) (in this case, for example, all base stations are 4G base stations or all are 5G base stations), or may be base stations of different RATs (in this case, for example, one base station is a fourth-generation 4G base station and another base station is a fifth-generation 5G base station).

[0316] For example, FIG. 16 is another schematic diagram of a wireless communication system 300 applicable to an embodiment of the present application. Referring to FIG. 16, UE 320 may communicate with base station 311 and base station 312 using DC technology, and base station 311 and base station 312 jointly access core network 330. Core network 330 may be a 4G core network or a 5G core network.

[0317] The network side can use the resources of multiple base stations to provide communication services to the UE and offer high-rate transmission to the UE. In the DC scenario, for the UE, the base station that exchanges core network and control plane signaling with the UE is called the master node (MN), and another base station is called the secondary node (SN). The MN may sometimes be called the master base station, and the SN may sometimes be called the secondary base station. Each base station has different RLC entities and different MAC entities. In the DC scenario, the data radio bearer (DRB) can be classified into the following three types: the master cell group bearer (MCG bearer), the secondary cell group bearer (SCG bearer), and the split bearer. The MCG bearer indicates that the RLC entity and the MAC entity of the DRB are in the master base station, and the SCG bearer indicates that the RLC entity and the MAC entity of the DRB are in the secondary base station. The split bearer means that the RLC entity and the MAC entity of the DRB exist in both the master base station and the secondary base station. Similarly, the bearer terminated by PDCP at the MN may be called the MN terminated bearer. That is, downlink (DL) data reaches the MN directly from the core network, is processed by the PDCP / SDAP of the MN, and then sent to the UE through the RLC / MAC. The uplink (UL) data is sent to the core network after being processed by the PDCP / SDAP of the MN. The bearer terminated by PDCP at the SN may be called the SN terminated bearer. That is, DL data reaches the SN directly from the core network, is processed by the PDCP / SDAP of the SN, and then sent to the UE through the RLC / MAC. The UL data is sent to the core network after being processed by the PDCP / SDAP of the SN.Note that in the present invention, the SDAP layer is a protocol layer that exists only when the terminal device is connected to the 5G core network.

[0318] In addition to the above, in dual connectivity, the master base station and the secondary base station may have RRC entities, and both may generate RRC messages (i.e., control messages, such as measurement messages). For example, FIG. 17 is a schematic diagram of a DC control plane architecture applicable to an embodiment of the present application. The master base station communicates with the core network through a communication interface (e.g., NG-C interface), the master base station communicates with the secondary base station through a communication interface (e.g., Xn-C interface), the master base station communicates with the UE through a communication interface (e.g., Uu interface), and the secondary base station communicates with the UE through a communication interface (e.g., Uu interface).

[0319] The secondary base station may directly transmit the RRC message generated by the secondary base station to the UE. In this case, the RRC message transmitted by the UE to the secondary base station is also directly transmitted to the secondary base station. The RRC message directly exchanged between the secondary base station and the UE is called a signalling radio bearer 3 (SRB3). Instead, the secondary base station may notify the master base station of the generated RRC message, and the master base station transmits the RRC message to the UE. In this case, the UE transmits the RRC message that needs to be transmitted to the secondary base station using the master base station. When the UE is in a DC scenario, the user plane of the secondary base station may be connected to the core network connected to the master base station, that is, the core network may directly send data to the UE using the secondary base station.

[0320] The interface between the devices of this application (in this case, for example, a master base station and a secondary base station can communicate with each other through the Xn-C interface) is only an example for explanation and should be understood not to limit the protection scope of the embodiments of this application.

[0321] The scenarios to which this application is applicable may include DC types such as evolved universal terrestrial radio access and new radio dual connectivity (E-UTRA-NR dual connectivity, EN-DC), next-generation radio access network evolved universal terrestrial radio access and new radio dual connectivity (NG-RAN E-UTRA-NR dual connectivity, NGEN-DC), new radio and evolved universal terrestrial radio access dual connectivity (NR-E-UTRA dual connectivity, NE-DC), and new radio and new radio dual connectivity (NR-NR dual connectivity, NR-DC).

[0322] In EN-DC, the master base station is an LTE base station (such as an eNB) connected to the 4G core network, and the secondary base station is an NR base station (such as a gNB).

[0323] In NGEN-DC, the master base station is an LTE base station connected to the 5G core network, and the secondary base station is an NR base station.

[0324] In NE-DC, the master base station is an NR base station connected to the 5G core network, and the secondary base station is an LTE base station. Since the UE of the EN-DC network cannot camp on the NR cell at the start of 5G, EN-DC is also called NSA. The NR base station on which the UE can camp may be called an SA NR base station.

[0325] In NR-DC, the master base station is an NR base station connected to the 5G core network, and the secondary base station is an NR base station.

[0326] For example, FIG. 18 is a schematic diagram of the network-side protocol stack of the MCG bearer, SCG bearer, and split bearer in EN-DC. For example, FIG. 19 is a schematic diagram of the network-side protocol stack of the MCG bearer, SCG bearer, and split bearer in NGEN-DC / NE-DC / NR-DC. As can be seen from FIGS. 18 and 19, the transmission of each bearer needs to pass through RLC / MAC and PDCP / SDAP.

[0327] The UE can simultaneously receive services from multiple cells under one base station. The serving cell group provided to the UE by the MN may be called the master cell group (MCG), and the MCG includes one or more cells. The serving cell group provided to the UE by the SN may be called the secondary cell group (SCG), and the SCG includes one or more cells. When there is only one cell in the MCG, the cell is the primary cell (PCell) of the UE. When there is only one cell in the SCG, the cell is the primary secondary cell (primary secondary cell, PSCell) of the UE. In NR, for the purpose of unifying various terms, the PCell and the PSCell are collectively called the special cell (SpCell). When there are multiple cells in the MCG or SCG, the cells other than the SpCell may be called the secondary cell (SCell). In order to provide transmission resources to the UE, carrier aggregation can be performed on the SCell and SpCell of the MCG or SCG.

[0328] It should be understood that the application scenarios of the present application are not limited to the above DC scenarios. The present application is further applicable to DC scenarios of other systems. For example, it is further applicable to DC scenarios including 5G base stations and WIFI, or DC scenarios including base stations deployed in licensed spectrum and base stations deployed in unlicensed spectrum.

[0329] To facilitate the understanding of the embodiments of the present application, some basic concepts of the embodiments of the present application are briefly described. Although the basic concepts described below are briefly described using the basic concepts determined by the current protocol as an example, it should be understood that the embodiments of the present application are not limited to being applicable only to existing communication systems. Therefore, all the standard names that appear when the existing communication system is used as an example for explanation are for the explanation of functions, and the specific names are not limited.

[0330] 1. Carrier Aggregation (CA): A technology set for one terminal device so that multiple carriers (cells) perform data transmission together.

[0331] 2. Primary Cell (PCell): A cell deployed on the main frequency (i.e., the cell operating on the main carrier). The PCell is the corresponding cell where the terminal device starts the first connection establishment process or the connection re - establishment process. Further, when the terminal device starts the first connection establishment process or the connection re - establishment process with a cell, the cell is called a PCell. The cell may also be indicated as a PCell during handover.

[0332] 3. Primary Secondary Cell (PSCell): A cell in which the terminal device performs random access or the first physical uplink shared channel (PUSCH) transmission in the SCG (for example, when an SCG change occurs and the random access process is not required, the UE starts the first PUSCH transmission), or a cell in which the terminal device performs random access in the synchronization reconfiguration process in the SCG cell.

[0333] 4. Secondary Cell (SCell): A cell that operates on a secondary carrier. After the RRC connection is established, the SCell may be configured to provide additional radio resources. In a dual connectivity system, cells of MCG and SCG other than the PCell and PSCell may be referred to as SCell. It should be noted that in some places, the PSCell is also applicable as an SCell, that is, the SCell includes the PSCell.

[0334] 5. Serving Cell: For a terminal device in the RRC_CONNECTED state, if carrier aggregation or dual connectivity is not configured, there is only one serving cell, that is, the PCell, or if carrier aggregation or dual connectivity is configured, the serving cells of the terminal device include the PCell, PSCell, and all SCells.

[0335] It should be understood that each component carrier (CC) corresponds to an independent cell. In a possible design, a terminal device configured using carrier aggregation or dual connectivity may be connected to one PCell and up to 31 SCells. The PCell, PSCell, and all SCells of the terminal device form the serving cell set of the terminal device. The serving cell of the terminal device may be a PCell, PSCell, or SCell.

[0336] In the prior art, when applying dual connectivity technology, if a terminal device does not need to use a secondary cell group (SCG) to provide a communication service to the terminal device, the terminal device may temporarily suspend the SCG. For example, the configuration of the SCG may be suspended. In addition, the terminal device does not perform data transmission using the SCG, thereby reducing the energy consumption of the terminal device and the network device. In addition to the above, when the terminal device needs to use the SCG to provide a communication service to the terminal device, the terminal device may restore the configuration of the SCG, and may further perform data transmission using the SCG to meet the requirements of the terminal device for the data transmission rate.

[0337] Currently, in the prior art, in the present embodiment of the present application, the suspension of the SCG by the UE can be understood as that while the UE suspends signaling transmission and / or data transmission using the communication link of the SCG, the terminal retains or stores some or all of the configurations of the SCG.

[0338] Suspending the SCG means that while the UE temporarily stops using the SCG for data transmission, it retains the configuration of the SCG. In particular, when the UE does not need to use the SCG to provide a service to the UE or when the UE does not need to use the SCG link, for example, when the data rate of the UE is low, the UE may suspend the SCG according to the instruction of the network side. For example, the configuration of the SCG may be retained, and the UE does not perform data transmission using the SCG. When the UE needs to use the SCG to provide a service to the UE or when the UE needs to use the SCG link, for example, when the data rate of the UE increases, the UE may perform restoration / resumption or activation of the configuration of the SCG according to the instruction of the network side, and may perform data transmission using the SCG.

[0339] It should be noted that the reserved SCG is also used when the SCG is in a reserved state, the SCG is in an idle / inactive state, or the UE is in a dormant state, a non-active state, an inactive state, etc. in the SCG. Recovering the SCG may be called recovering the SCG or restoring the SCG. The recovered SCG or the non-reserved SCG may also be called when the SCG is in a busy / active state, or the UE is in a busy or active state, an activated state, etc. in the SCG. When the SCG is reserved, it should be noted that the terminal device does not need to monitor the PDCCH in the SCG and does not need to perform beam management (that is, the terminal device does not send the measurement results of each beam of the SCG to the SN, and the SN does not notify the terminal device to change the current serving beam).

[0340] The present invention relates to the way the UE communicates with the SCG when it is instructed again by the network device to recover or activate it. The scenario where the SCG is reserved is mainly the scenario of burst services of communication services, that is, there is a service communication request during a certain period and there is no service communication request during a certain period. When the SCG is reserved, the terminal device does not monitor the PDCCH. Therefore, the present invention proposes a method for determining the beam used by the terminal device to communicate with the SCG in a scenario where the terminal device does not need to perform random access to the SCG when the timing advance timer has not expired when the SCG is recovered or re-activated.

[0341] Figure 20 is a schematic flowchart of another communication method according to an embodiment of the present application. As shown in Figure 20, the communication method includes the following steps 2001 to 2006.

[0342] 2001: The network device sends the first information to the terminal device, and the first information is used to notify the terminal device to hold the SCG.

[0343] It should be noted that the terminal device is a terminal device configured using MR-DC.

[0344] It should be noted that the first information is sent by the network device, and the network device may be an MN or an SN. In other words, the first information may be sent by the MN or the SN. The MN or SN may send the first information to the terminal device in multiple ways. For example, it may be sent using a MAC control element (CE), an RRC message, L1 indication information, etc.

[0345] 2002: The terminal device holds the SCG.

[0346] After the terminal device receives the first information, the terminal device holds the SCG. The terminal device maintains the SCG setting.

[0347] When the SCG is held, the terminal device performs beam failure detection with the SCG, and the terminal device also maintains a timing advance timer. The timing advance timer is started when the terminal device receives a timing advance command (TA command), and the terminal device may receive a timing advance command before receiving the first information.

[0348] When the SCG is held, the terminal device performs beam failure detection before the timing advance timer expires. When the timing advance timer expires, the terminal device stops performing beam failure detection. If the terminal device detects a beam failure before the timing advance timer expires, the terminal device may stop or release the timing advance timer.

[0349] In 2003, the network device transmits the second information to the terminal device, and the second information is used to notify the terminal device to recover the SCG.

[0350] It should be noted that the second information is transmitted by the network device, and the network device may be an MN or an SN. In other words, the second information may be transmitted by the MN or the SN. The MN or SN may transmit the second information to the terminal device in a plurality of ways. For example, when the second information is transmitted by the MN, the MN may transmit the second information using a MAC control element (CE), an RRC message, L1 indication information, etc. When the second information is transmitted by the SN, the SN may transmit the second information using an RRC message.

[0351] In 2004, the terminal device recovers or activates the SCG.

[0352] In the present embodiment of the present application, after receiving the second information, the terminal device recovers or activates the SCG. The terminal device recovers or activates the configuration information of the SCG.

[0353] In 2005, if the timing advance timer has not expired, been stopped, or been released, the terminal device transmits PUCCH or PUSCH to the SCG, and the transmission beam of the PUCCH and PUSCH is the same as the transmission beam of the previous uplink transmission (i.e., the transmission beam of the uplink PUCCH or PUSCH performed by the terminal device on the SCG before the SCG was last suspended), or the same as the beam corresponding to the previous uplink PUCCH or PUSCH (i.e., the beam corresponding to the PUCCH or PUSCH on the SCG transmitted by the terminal device before the SCG was last suspended).

[0354] In 2006, if the timing advance timer has not expired, been stopped, or been released, the terminal device monitors the PDCCH of the SCG, and the receiving beam used to monitor the PDCCH of the SCG is the same as the receiving beam used to monitor the PDCCH in the previous SCG (i.e., the receiving beam used by the terminal device to monitor the PDCCH of the SCG before the previous suspension of the SCG).

[0355] When the timing advance timer expires, is stopped, or is released, the terminal device performs random access for the SCG.

[0356] FIG. 21 is a schematic diagram of the structure of a communication device according to an embodiment of the present application. The communication device shown in FIG. 21 may be configured to perform some or all of the functions of the terminal device in the method embodiment described in FIG. 3. This device may be a terminal device, a device in the terminal device, or a device that can be used together with the terminal device. Alternatively, the communication device may be a chip system. The communication device shown in FIG. 21 may include a communication unit 2101 and a processing unit 2102. The processing unit 2102 is configured to perform data processing. A receiving unit and a transmitting unit are incorporated in the communication unit 2101. The communication unit 2101 may also be called a transceiver unit. Alternatively, the communication unit 2101 may be divided into a receiving unit and a transmitting unit. The following processing unit 2102 and communication unit 2101 are similar. Details will not be repeated here.

[0357] After successfully performing the first random access in the radio resource control inactive (RRC inactive) state, the communication unit 2101 is configured to receive the downlink control information (DCI) transmitted by the access network device using the first receiving beam, where the first receiving beam is the same as the receiving beam for the downlink transmission of the first random access.

[0358] For other possible implementation examples of the communication device, refer to the relevant description of the functions of the terminal device in the method embodiment corresponding to FIG. 3. Details are not described repeatedly in this description.

[0359] FIG. 21 is a schematic diagram of the structure of a communication device according to an embodiment of the present application. The communication device shown in FIG. 21 may be configured to perform some or all of the functions of the terminal device in the method embodiments described with reference to FIGS. 6 to 11. This device may be a terminal device, a device in the terminal device, or a device that can be used together with the terminal device. Alternatively, the communication device may be a chip system. The communication device shown in FIG. 21 may include a communication unit 2101 and a processing unit 2102.

[0360] The communication unit 2101 is configured to transmit an RRC recovery request and first uplink data to an access network device through a first configured grant (CG) resource using a first transmission beam in a radio resource control (RRC) inactive state, where the first transmission beam is the same as the transmission beam of the terminal device in the RRC connected state, or the first transmission beam is the same as the transmission beam in the previous data transmission process when the terminal device was in the RRC inactive state.

[0361] For other possible implementation examples of the communication device, refer to the relevant description of the functions of the terminal device in the method embodiments corresponding to FIGS. 6 to 11. Details are not described repeatedly in this description.

[0362] FIG. 21 is a schematic diagram of the structure of a communication device according to an embodiment of the present application. The communication device shown in FIG. 21 may be configured to perform some or all of the functions of the first access network device in the method embodiments described in FIGS. 12, 13A, and 13B. This device may be the first access network device, or a device within the first access network device, or a device that can be used together with a terminal device. Alternatively, the communication device may be a chip system. The communication device shown in FIG. 21 may include a communication unit 2101 and a processing unit 2102.

[0363] The communication unit 2101 is configured to receive a second message 1 transmitted by a terminal device in a radio resource control inactive (RRC inactive) state, where the second message 1 includes a second preamble. The communication unit 2101 is further configured to transmit a second message 2 to the terminal device, where the second message 2 includes a second cell radio network temporary identifier (C-RNTI). The communication unit 2101 is further configured to receive a second message 3 transmitted by the terminal device, where the second message 3 includes the C-RNTI of the terminal device. The communication unit 2101 is further configured to transmit a second message 4 to the terminal device, where the physical downlink control channel (PDCCH) of the second message 4 is scrambled by the C-RNTI of the terminal device.

[0364] Optionally, a second Temporary C-RNTI is used for the retransmission scheduling of the second MSG3.

[0365] In a possible implementation example, before receiving the second message 1 sent by a terminal device in the Radio Resource Control Inactive (RRC Inactive) state, the communication unit 2101 receives the first message 1 sent by the terminal device in the Radio Resource Control Inactive (RRC Inactive) state, and is further configured such that the first message 1 includes a first preamble. The communication unit 2101 is further configured to send the first message 2 to the terminal device, such that the first message 2 includes a first Temporary C-RNTI. The communication unit 2101 receives the first message 3 sent by the terminal device, and is further configured such that the first message 3 includes a Radio Resource Control (RRC) recovery request and first uplink data. The communication unit 2101 is further configured to send the first message 4 to the terminal device, such that the second message 4 includes collision resolution. The communication unit 2101 sends the first Temporary C-RNTI to a second access network device, and is further configured such that the C-RNTI of the terminal device is the first Temporary C-RNTI.

[0366] FIG. 21 is a schematic diagram of the structure of a communication device according to an embodiment of the present application. The communication device shown in FIG. 21 may be configured to perform some or all of the functions of the first access network device in the method embodiments described in FIGS. 14 and 15. The device may be the first access network device, or a device in the first access network device, or a device that can be used together with the terminal device. Alternatively, the communication device may be a chip system. The communication device shown in FIG. 21 may include a communication unit 2101 and a processing unit 2102.

[0367] The communication unit 2101 is configured to receive a second message A sent by a terminal device in a radio resource control inactive (RRC inactive) state, where the second message A includes a second preamble and a cell radio network temporary identifier (C-RNTI) of the terminal device. The communication unit 2101 is further configured to send a second message B to the terminal device, where the physical downlink control channel (PDCCH) of the second message B is scrambled using the C-RNTI of the terminal device.

[0368] In a possible implementation, before receiving the second message A sent by a terminal device in an RRC inactive state, the communication unit 2101 is configured to receive a first message A sent by the terminal device in the RRC inactive state, where the first message A includes a first preamble, a radio resource control (RRC) recovery request, and first uplink data. The communication unit 2101 is configured to send a first message B to the terminal device, where the 1 first message B includes collision resolution and a first C-RNTI. The communication unit 2101 is further configured to send the first C-RNTI to a second access network device, where the C-RNTI of the terminal device is the first C-RNTI.

[0369] FIG. 21 is a schematic diagram of the structure of a communication device according to an embodiment of the present application. The communication device shown in FIG. 21 may be configured to perform some or all of the functions of the terminal device in the method embodiment described in FIG. 20. This device may be a terminal device, a device in the terminal device, or a device that can be used together with the terminal device. Alternatively, the communication device may be a chip system. The communication device shown in FIG. 21 may include a communication unit 2101 and a processing unit 2102.

[0370] The communication unit 2101 is configured to receive second information transmitted by a network device and to be used to notify the terminal device so that the second information restores the SCG. The processing unit 2102 is configured to restore or activate the SCG. The communication unit 2101 is further configured to transmit PUCCH or PUSCH to the SCG if the timing advance timer has not expired, has not been stopped, or has not been released, and the transmission beam of the PUCCH and PUSCH is the same as the transmission beam of the previous uplink transmission, or to monitor the PDCCH of the SCG, and the reception beam used to monitor the PDCCH of the SCG is the same as the reception beam used to monitor the PDCCH in the previous SCG.

[0371] FIG. 22 shows a communication device 220 according to an embodiment of the present application. The communication device 220 is configured to implement the functions of the terminal device in FIGS. 3 to 15 or FIG. 20. This device may be a terminal device or a device used in a terminal device. The device used in the terminal device may be a chip system or a chip in the terminal device. The chip system may include a chip or may include a chip and another discrete component.

[0372] Alternatively, the communication device 220 is configured to implement the functions of the first access network device in FIGS. 3 to 15. This device may be a first access network device or a device used in a first access network device. The device used in the first access network device may be a chip system or a chip of the first access network device.

[0373] The communication device 220 includes at least one processor 2220 configured to implement the data processing function of the terminal device or the first access network device in the method provided in the embodiments of the present application. The device 220 may further include a communication interface 2210 configured to implement the transmission and reception operations of the terminal device or the first access network device in the method provided in the embodiments of the present application. In the present embodiment of the present application, the communication interface may be a transceiver, a circuit, a bus, a module, or another type of communication interface, and is configured to communicate with another device using a transmission medium. For example, the communication interface 2210 is used by a device in the device 220 to communicate with another device. The processor 2220 transmits and receives data through the communication interface 2210 and is configured to implement the method shown in FIGS. 3 to 15 or FIG. 20 in the above method embodiment.

[0374] The device 220 may further include at least one memory 2230 configured to store program instructions and / or data. The memory 2230 is connected to the processor 2220. The connection in the present embodiment of the present application may be an electrical form, a mechanical form, or an indirect connection or communication connection between other forms of devices, units, or modules, and is used for information exchange between devices, units, or modules. The processor 2220 may operate in cooperation with the memory 2230. The processor 2220 may execute the program instructions stored in the memory 2230. At least one of the at least one memory may be included in the processor.

[0375] After the device 220 is started, the processor 2220 may read a software program in the memory 2230, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be sent wirelessly, after performing baseband processing on the data to be sent, the processor 2220 outputs a baseband signal to a high-frequency circuit (not shown), and the high-frequency circuit performs high-frequency processing on the baseband signal and then transmits a high-frequency signal to the outside in the form of an electromagnetic wave through an antenna. When data is sent to the device 220, the high-frequency circuit receives the high-frequency signal through the antenna, converts the high-frequency signal into a baseband signal, and outputs the baseband signal to the processor 2220. The processor 2220 converts the baseband signal into data and processes the data.

[0376] In another embodiment, the high-frequency circuit and the antenna may be arranged independently of the processor 2220 that performs baseband processing. For example, in a scenario where they are to be dispersed, the high-frequency circuit and the antenna may be arranged at locations separated from the communication device.

[0377] In the present embodiment of the present application, the specific connection medium between the communication interface 2210, the processor 2220, and the memory 2230 is not limited. In the present embodiment of the present application, the memory 2230, the processor 2220, and the communication interface 2210 are connected through the bus 2240 in FIG. 22, and the bus is represented by a thick line in FIG. 22. The connection method with other components is only schematically described and is not limited thereto. The bus may be classified into an address bus, a data bus, a control bus, etc. Although only one thick line is used to represent the bus in FIG. 22 for ease of representation, this does not mean that there is only one bus or only one type of bus.

[0378] When the device 220 is particularly a device of a terminal device or a first access network device, for example, when the device 220 is particularly a chip or a chip system, the communication interface 2210 may output or receive a baseband signal. When the device 220 is particularly a terminal device or a first access network device, the communication interface 2210 may output or receive a high-frequency signal. In the present embodiment of the present application, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field-programmable gate array or another programmable logic device, discrete gates or transistor logic devices, or discrete hardware components, and may implement or perform the methods, operations, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor or any conventional processor, etc. The operations of the methods disclosed with reference to the embodiments of the present application may be directly performed and completed by a hardware processor, or may be performed and completed by a combination of a hardware module and a software module of the processor.

[0379] In the embodiments of the present application, a computer-readable storage medium is further provided. The computer-readable storage medium stores instructions. When the instructions are run on a processor, the method procedures of the above method embodiments are implemented.

[0380] In the embodiments of the present application, a computer program product is further provided. When the computer program product runs on a processor, the method procedures of the above method embodiments are implemented.

[0381] It should be noted that, for the sake of brevity, the above method embodiments are described as a combination of a series of operations. However, according to the present application, some operations may be performed in a different order or simultaneously, so those skilled in the art will naturally understand that the present application is not limited to the described operation sequence. It is further understood by those skilled in the art that not all of the embodiments described herein belong to the embodiments, and the operations and modules involved are not necessarily required by the present application.

[0382] There may be cross-references to the descriptions of the embodiments provided in the present application, and there are different points of attention in the descriptions of the embodiments. For parts not described in detail in the embodiments, refer to the relevant descriptions of other embodiments. For the sake of facilitating and simplifying the description, for the functions of the devices and apparatuses provided in the embodiments of the present application and the operations performed by the devices and apparatuses, refer to the relevant descriptions of the method embodiments of the present application. There may also be cases where the method embodiments and the apparatus embodiments are cross-referenced, combined, or cited.

[0383] Finally, it should be noted that the above embodiments do not limit the present application, but only intend to explain the technical solutions of the present application. Although the present application is described in detail with respect to the above embodiments, even in that case, those skilled in the art will naturally understand that modifications can be made to the technical solutions described in the above embodiments or equivalent substitutions can be made by those skilled in the art for some or all of the technical features thereof, without departing from the scope of the technical solutions of the embodiments of the present application.

Description of Reference Numerals

[0384] 220 Communication device 300 Wireless communication system 311 Base station 312 Base station 320 UE 330 Core network 2101 Communication unit 2102 Processing unit 2210 Communication Interface 2220 Processor 2230 Memory 2240 Bus

Claims

1. A communication method, comprising: After successfully performing a first random access in a radio resource control (RRC) inactive state, receiving, by a terminal device, downlink control information (DCI) transmitted by an access network device using a first reception beam, wherein the DCI indicates an uplink transmission resource, and the first reception beam is the same as the reception beam for the downlink transmission of the first random access; Performing, by the terminal device, an uplink transmission through the uplink transmission resource using a first transmission beam, wherein the first transmission beam is the same as the transmission beam for the uplink transmission of the first random access; A method comprising the above steps.

2. The DCI further indicates a downlink transmission resource, and the method further comprises: Performing, by the terminal device, a downlink transmission through the downlink transmission resource, wherein the reception beam for the downlink transmission is the same as the first reception beam. The method according to claim 1, further comprising the above step.

3. The method according to claim 1 or 2, wherein the first random access is a four-step random access, and the first reception beam is the same as the reception beam for message 2 or message 4 of the first random access.

4. The method according to claim 1 or 2, wherein the first random access is a two-step random access, and the first reception beam is the same as the reception beam for message B of the first random access.

5. The method according to claim 1 or 2, wherein the first random access is a four-step random access, and the first transmission beam is the same as the transmission beam for message 1 or message 3 of the first random access.

6. The method according to claim 1 or 2, wherein the first random access is a two-step random access, and the first transmission beam is the same as the transmission beam for message A of the first random access.

7. Receiving, by the terminal device, indication information transmitted by the access network device, wherein the indication information indicates monitoring a physical downlink control channel (PDCCH) corresponding to a cell radio network temporary identifier (C-RNTI), and the C-RNTI is the C-RNTI of the terminal device. A step of monitoring, by the terminal device, the PDCCH corresponding to the C-RNTI, wherein the DCI is carried on the PDCCH corresponding to the C-RNTI The method according to any one of claims 1 to 6, further comprising

8. The first random access is a 4-step random access, and the indication information is carried in message 4 of the first random access, or The first random access is a 2-step random access, and the indication information is carried in message B of the first random access. The method according to claim 7

9. When the indication information is a first RRC release message and the first RRC release message does not carry a next-hop chain count (NCC) indication, an inactive-radio network temporary identifier (I-RNTI), or a pause setting, the method comprises a step of instructing to monitor the PDCCH corresponding to the C-RNTI, wherein the pause setting indicates to the terminal device to stay in the RRC inactive state. The method according to claim 7 or 8

10. When a first condition is satisfied, a step of stopping, by the terminal device, monitoring a physical downlink control channel (PDCCH) corresponding to a cell radio network temporary identifier (C-RNTI), wherein the DCI is carried on the PDCCH corresponding to the C-RNTI, the C-RNTI is the C-RNTI of the terminal device, and the first condition is The reference signal received power (RSRP) of the first received beam is less than a first threshold, or The consecutive N RSRPs of the first received beam are less than a first threshold, where N is an integer greater than or equal to 2, or Within a first time period, the consecutive N RSRPs of the first received beam are less than a first threshold, where N is an integer greater than or equal to 2, or The reference signal received power (RSRP) of the received beam corresponding to the first transmitted beam is less than a second threshold, or The consecutive N RSRPs of the received beam corresponding to the first transmitted beam are less than a second threshold, where N is an integer greater than or equal to 2 During a first time period, that the continuous N received signal strength references (RSRPs) of the received beam corresponding to the first transmitted beam are less than a second threshold, where N is an integer greater than or equal to 2, or that a timer expires is one of the steps The method according to claim 2, further comprising this step.

11. When a first condition is satisfied, a step of performing a second random access by the terminal device, where the first condition is that the reference signal received power (RSRP) of the first received beam is less than a first threshold, or that the continuous N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2, or that during a first time period, the continuous N RSRPs of the first received beam are less than the first threshold, where N is an integer greater than or equal to 2, or that the reference signal received power (RSRP) of the received beam corresponding to the first transmitted beam is less than a second threshold, or that the continuous N RSRPs of the received beam corresponding to the first transmitted beam are less than the second threshold, where N is an integer greater than or equal to 2, or that during a first time period, the continuous N RSRPs of the received beam corresponding to the first transmitted beam are less than the second threshold, where N is an integer greater than or equal to 2, or that a timer expires is one of the steps The method according to claim 2, further comprising this step.

12. The first random access and the second random access are four-step random accesses, message 2 of the first random access includes a first Temporary C-RNTI, message 3 of the second random access carries the C-RNTI of the terminal device, the C-RNTI of the terminal device is the same as the first Temporary C-RNTI, and the PDCCH of message 4 of the second random access is scrambled using the C-RNTI of the terminal device. The method according to claim 11.

13. The first random access and the second random access are two-step random accesses, message B of the first random access includes a first C-RNTI, The message A of the second random access carries the C-RNTI of the terminal device, the C-RNTI of the terminal device is the same as the first C-RNTI, and the PDCCH of the message B of the second random access is scrambled using the C-RNTI of the terminal device. The method according to claim 11.

14. The first received beam corresponds to a first preamble, or the first received beam corresponds to the time-frequency resource of a first preamble. The first random access is a four-step random access, and the first preamble is the preamble of message 1 of the first random access, or The first random access is a two-step random access, and the first preamble is the preamble of message A of the first random access. The method according to any one of claims 1 to 13.

15. A step of transmitting, by the terminal device, a hybrid automatic repeat request (HARQ) feedback to the access network device, wherein a transmission beam of the HARQ feedback is the same as the first transmission beam. The method according to claim 1, further comprising the step.

16. A step of receiving, by the terminal device, a hybrid automatic repeat request (HARQ) feedback transmitted by the access network device, wherein a reception beam of the HARQ feedback is the same as the first reception beam. The method according to claim 2, further comprising the step.

17. The first received beam, the received beam of the downlink transmission of the first random access, and the received beam of the first SSB are the same, and the first SSB corresponds to the preamble of the first random access. The method according to claim 1.

18. A communication device comprising a module configured to perform the method according to any one of claims 1 to 17.

19. A communication device comprising a processor and a memory, the processor being connected to the memory, and the processor being configured to implement the method according to any one of claims 1 to 17.

20. A communication device comprising a processor and an interface circuit, wherein the interface circuit is configured to receive a signal from a communication device other than the communication device and transmit the signal to the processor, or transmit a signal from the processor to a communication device other than the communication device, and the processor is configured to implement the method according to any one of claims 1 to 17 by using a logic circuit or executing code instructions.

21. A computer-readable storage medium storing a computer program or instructions, wherein when the computer program or the instructions are executed by a communication device, the method according to any one of claims 1 to 17 is implemented.

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