Communication method and communication apparatus

Abstract

Provided in the present application are a communication method and a communication apparatus. A remote terminal device may save first context, which is used for transmitting small data between the remote terminal device and a network device by means of a relay terminal device. If a transmission condition for the small data is met, the remote terminal device may recover the first context, and transmit first small data between the remote terminal device and the network device by means of the relay terminal device in an RRC inactive state. In this way, the problems of power consumption and signaling overheads caused by the need for the remote terminal device to enter an RRC connected state to transmit the first small data between the remote terminal device and the network device is avoided.

Description

Communication method and communication device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on September 22, 2023, with application number 202311247967.5 and application name “Communication Method and Communication Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communications, and more particularly to a communication method and a communication device in the field of communications. Background Art

[0003] In the field of wireless communication technology, a terminal device exists in three states at the radio resource control (RRC) layer: RRC connected (RRC_CONNECTED), RRC idle (RRC_IDLE), and RRC inactive (RRC_INACTIVE). Generally, data can only be transmitted between the terminal device and the network device when the terminal device is in the RRC_CONNECTED state. If no data from the terminal device is transmitted between the terminal device and the network device within a preset period of time in the RRC_CONNECTED state, the terminal device may enter the RRC_INACTIVE state.

[0004] However, in some business scenarios, terminal devices in the RRC IDLE or RRC INACTIVE states need to transmit data, and the data packets to be transmitted are very small, which can be called small data. Examples of such data packets are instant messaging messages, heartbeat packets, and periodic data. To transmit small data, the terminal device needs to enter the RRC_CONNECTED state from the RRC_INACTIVE state. However, the signaling required for the terminal device to enter the RRC CONNECTED state from the RRC IDLE or RRC INACTIVE state is even greater than that for small data, resulting in unnecessary power consumption and signaling overhead for the terminal device.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a communication method and a communication device, which can avoid the power consumption problem caused by the need for the remote terminal device to enter the RRC connection state to transmit the first packet data between the remote terminal device and the network device.

[0007] In a first aspect, a communication method is provided, which is applied to a remote terminal device, including: saving a first context for transmitting small packet data between the remote terminal device and the network device through a relay terminal device; if the transmission conditions of the small packet data are met, restoring the first context; and transmitting the first small packet data between the remote terminal device and the network device through the relay terminal device in a non-connected state of radio resource control RRC based on the restored first context.

[0008] In the above scheme, the remote terminal device can save the first context for transmitting small packet data between the remote terminal device and the network device through the relay terminal device. If the transmission conditions of the small packet data are met, the remote terminal device can restore the first context and transmit the first small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state, thereby avoiding the power consumption problem caused by the remote terminal device needing to enter the RRC connected state to transmit the first small packet data between the remote terminal device and the network device through the relay terminal device.

[0009] Optionally, the RRC non-connected state may be an RRC inactive state or an RRC idle state, etc.

[0010] In some possible implementations, the transmission condition includes at least one of the following: the amount of data related to the transmission of small packet data is less than or equal to a first data amount threshold value, the reference signal received power RSRP between the remote terminal device and the relay terminal device is greater than or equal to a first RSRP threshold value, or a first indication information sent by the network device is received, and the first indication information indicates that the network device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state.

[0011] Optionally, the data volume associated with packet data transmission is less than or equal to a first data volume threshold value, which is used in situations where there is an uplink data transmission requirement. When the remote terminal device has an uplink data transmission requirement, the remote terminal device needs to determine the transmission condition.

[0012] Optionally, the transmission condition that the reference signal received power RSRP between the remote terminal device and the relay terminal device is greater than or equal to the first RSRP threshold value is applicable to uplink transmission and may also be applicable to downlink transmission.

[0013] Optionally, the transmission condition for receiving the first indication information sent by the network device is applicable to downlink transmission and may also be applicable to uplink transmission.

[0014] In some possible implementations, the data volume associated with packet data transmission includes the size of a PC5 radio link control RLC protocol data unit PDU corresponding to the first packet data and / or the size of a PC5 RLC service data unit SDU corresponding to the first packet data.

[0015] In some possible implementations, before transmitting the first packet data between the remote terminal device and the network device through the relay terminal device based on the restored first context in the radio resource control RRC non-connected state, the communication method further includes:

[0016] If the transmission conditions of the small packet data are met, a small packet data transmission process is initiated, and a first RRC request message is sent to the network device through the relay terminal device. The first RRC request message includes second indication information, and the second indication information is used to indicate that the remote terminal device has a small packet data transmission requirement.

[0017] In the above solution, when the remote terminal device determines that the conditions for transmitting small packet data are met, it can initiate a small packet data transmission process and send a second indication message containing a transmission requirement of the remote terminal device to the network device via the relay terminal device. The network device can then learn of the remote terminal device's transmission requirement based on the second indication message. In this case, the relay terminal device does not need to parse the first RRC request message, which can simplify the design.

[0018] In some possible implementations, the communication method further includes: if the transmission conditions of the small packet data are met, sending second indication information to the relay terminal device, wherein the second indication information is used to indicate that the remote terminal device has a transmission requirement for the small packet data.

[0019] In the above solution, after determining that the transmission conditions for the small packet data are met, the remote terminal device may send second indication information to the relay terminal device, where the second indication information may indicate that the remote terminal device has a transmission requirement for the small packet data.

[0020] In some possible implementations, the second indication information is included in information of a media access control (MAC) layer. Optionally, the information of the MAC layer is a MAC control element (CE) or a MAC subheader.

[0021] In some possible implementations, the second indication information is included in information of a Sidelink Relay Adaptation Protocol (SRAP) layer. Optionally, the information of the SRAP layer is an SRAP subheader or an SRAP Protocol Data Unit (PDU).

[0022] In some possible implementations, before the first context based on the recovery is transmitted between the remote terminal device and the network device through the relay terminal device in the radio resource control RRC non-connected state, the communication method also includes: if the transmission conditions of the packet data are met, initiating a packet data transmission process, and sending a first RRC request message to the network device through the relay terminal device.

[0023] In the above scheme, after the remote terminal device sends the second indication information to the relay terminal device, the remote terminal device can also send the first RRC request message to the relay terminal device. In this way, the relay terminal device can know from the second indication information that the remote terminal device has a transmission requirement for small packet data, so the relay terminal device can send the fifth indication information and the first RRC request message to the network device.

[0024] In some possible implementations, the communication method further includes: receiving, through the relay terminal device, third indication information sent by the network device, where the third indication information is used to indicate that the network device has successfully received the first RRC request message.

[0025] In the above scheme, the network device receives the first RRC request message and can send the third indication information to the remote terminal device through the relay terminal device. The remote terminal device can receive the third indication information sent by the network device through the relay terminal device. In this way, the remote terminal device can obtain the network device receiving the first RRC request message, which can trigger the remote terminal device to send small packet data.

[0026] Alternatively, the third indication information is used to indicate that the initial transmission of the packet data of the remote terminal device is successful, or to indicate that the network device has learned that the remote terminal device has a transmission requirement for packet data, or to indicate confirmation of the first RRC request message, or to trigger the remote terminal device to send the first packet data, etc.

[0027] In some possible implementations, the third indication information is included in information of a media access control (MAC) layer. Optionally, the information of the MAC layer is a MAC control element (CE) or a MAC subheader.

[0028] In some possible implementations, the third indication information is included in information of a Sidelink Relay Adaptation Protocol (SRAP) layer, or the third indication information is included in information of an RRC layer. Optionally, the SRAP layer information is an SRAP subheader, an SRAP data protocol data unit (PDU), or an SRAP control protocol data unit (PDU).

[0029] In some possible implementations, the communication method further includes: receiving fourth indication information from a relay terminal device, where the fourth indication information is used to indicate that the network device has successfully received the first RRC request message.

[0030] In the above scheme, the network device can indicate to the relay terminal device that the first RRC request message has been successfully received, and the relay terminal device can send a fourth indication message to the remote terminal device. The fourth indication information is used to indicate that the network device has successfully received the first RRC request message. In this way, the remote terminal device can learn from the relay terminal device that the network device has successfully received the first RRC request message.

[0031] In some possible implementations, the communication method further includes: acquiring capability information of the relay terminal device, where the capability information is used to indicate whether the relay terminal device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state;

[0032] The sending of a first RRC request message to the relay terminal device includes:

[0033] If the capability information is used to indicate that the relay terminal device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state, then the RRC request message is sent to the relay terminal device through the connection with the relay terminal device, and the first RRC request message includes the second indication information.

[0034] In the above scheme, if the relay terminal device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state, the remote terminal device can send a first RRC request message including second indication information to the relay terminal device.

[0035] In some possible implementations, the communication method further includes: obtaining capability information of the relay terminal device, the capability information being used to indicate whether the relay terminal device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state; wherein, sending the second indication information to the relay terminal device includes: if the capability information is used to indicate that the relay terminal device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state, then sending the second indication information to the relay terminal device.

[0036] In the above scheme, if the relay terminal device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state, the second indication information is sent to the relay terminal device.

[0037] In some possible implementations, the first context includes first configuration information of a PC5 relay RLC channel and / or a PC5 Sidelink Relay Adaptation Protocol (SRAP) configuration.

[0038] In the above solution, the remote terminal device can send the first packet data to the relay terminal device, or receive the first packet data from the relay terminal device according to the first configuration information of the PC5 relay RLC channel and / or the PC5 SRAP configuration included in the first context.

[0039] In some possible implementations, transmitting the first packet data between the remote terminal device and the network device through the relay terminal device in a radio resource control (RRC) non-connected state based on the restored first context includes:

[0040] The first packet data is sent to the relay terminal device based on the first configuration information.

[0041] In some possible implementations, transmitting the first packet data between the remote terminal device and the network device through the relay terminal device in a radio resource control (RRC) unconnected state based on the restored first context includes:

[0042] A first packet of data is sent and received from the relay terminal device based on the first configuration information.

[0043] In the above scheme, in uplink transmission, the remote terminal device can send the first packet data to the relay terminal device according to the first configuration information. For downlink transmission, the remote terminal device can receive the first packet data from the relay terminal device according to the first configuration information.

[0044] Optionally, the first context based on recovery transmits the first packet data between the remote terminal device and the network device through the relay terminal device in the wireless resource control RRC non-connected state, including: sending the first packet data to the relay terminal device based on the first configuration information and / or PC5 SRAP configuration.

[0045] Optionally, based on the restored first context, the first packet data between the remote terminal device and the network device is transmitted through the relay terminal device in the wireless resource control RRC non-connected state, including: sending and receiving the first packet data from the relay terminal device based on the first configuration information and / or PC5SRAP configuration.

[0046] In some possible implementations, the relay terminal device is in an RRC connected state, an RRC idle state, or an RRC inactive state.

[0047] In the above scheme, the relay terminal device can be in the RRC connected state, RRC idle state or RRC inactive state to send the first packet data of the remote terminal device to the network device; or the relay terminal device can be in the RRC connected state, RRC idle state or RRC inactive state to receive the first packet data from the network device.

[0048] In some possible implementations, the communication method further includes: receiving first timer information from the network device, where the first timer information is used to indicate a first duration of a first timer for transmitting packet data between the remote terminal device and the network device through the relay terminal device in an RRC unconnected state;

[0049] The first context based on the recovery transmits the first packet data between the remote terminal device and the network device through the relay terminal device in a radio resource control RRC non-connected state, including:

[0050] Within the first time period, based on the restored first context, the first packet data between the remote terminal device and the network device is transmitted through the relay terminal device in a radio resource control RRC non-connected state.

[0051] In the above solution, the remote terminal device can transmit the first packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state based on the restored first context within the first time period.

[0052] In a second aspect, a communication method is provided, which is applied to a relay terminal device, including: the relay terminal device receives second indication information from a remote terminal device in an RRC non-connected state, and the second indication information is used to indicate that the remote terminal device has a transmission requirement for small packet data; the relay terminal device sends the fifth indication information to the network device based on the second indication information in the RRC connected state, and the fifth indication information is used to indicate that the remote terminal device has a transmission requirement for small packet data.

[0053] In the above scheme, after the relay terminal device receives the second indication information from the remote terminal device, it can send the fifth indication information to the network device according to the second indication information. In this way, the network device can know that the remote terminal device has a small packet data transmission requirement according to the fifth indication information.

[0054] In some possible implementations, the second indication information is included in information of a media access control MAC layer; or, the second indication information is included in information of a sidelink relay adaptation protocol SRAP layer.

[0055] In some possible implementations, the MAC layer information is a MAC control element CE or a MAC subheader, or the SRAP layer information is a SRAP subheader or a SRAP protocol data unit PDU.

[0056] In some possible implementations, the communication method further includes: receiving a first radio resource control RRC request message from the remote device; and sending the first RRC request message to the network device.

[0057] In some possible implementations, the communication method further includes: receiving the first packet data from the remote terminal device; and not discarding the first packet data based on the second indication information.

[0058] In the above solution, after the relay terminal device receives the second indication information and the first packet data, it may not discard the first packet data according to the second indication information.

[0059] In a third aspect, a communication method is provided, which is applied to a first network device, including: sending a sixth indication message to a second network device, wherein the sixth indication message is used to request a relay terminal device to transmit a second context of packet data of a remote terminal device; and transmitting the first packet data of the remote terminal device through the relay terminal device based on the requested second context.

[0060] Optionally, the first network device sends the sixth indication information to the second network device, including: the first network device sends a first Xn interface request message to the second network device, and the first Xn interface request message may include the sixth indication information.

[0061] Optionally, the second network device may send a first Xn interface response message to the first network device, where the first Xn interface response message includes the second context.

[0062] In some possible implementations, the method further includes: sending seventh indication information to the second network device, wherein the seventh indication information is used to request a first context related to packet data of a remote terminal device; and transmitting the first packet data of the remote terminal device through the relay terminal device based on the requested first context.

[0063] Optionally, the first network device sends the seventh indication information to the second network device, including: the first network device sends a second Xn interface request message to the second network device, and the second Xn interface request message may include the seventh indication information.

[0064] Optionally, the second network device may send a second Xn interface response message to the first network device, where the second Xn interface response message includes the first context.

[0065] In some possible implementations, the sixth indication information and the seventh indication information are one piece of indication information, or the sixth indication information and the seventh indication information are different pieces of indication information.

[0066] In a fourth aspect, embodiments of the present application provide a communication device that implements any of the aforementioned aspects. The functionality may be implemented through hardware, or through hardware executing corresponding software implementations. The hardware or software includes one or more modules or units corresponding to the aforementioned functionality. For example, a transceiver module or unit, a processing module or unit, an acquisition module or unit, and the like.

[0067] In a fifth aspect, an embodiment of the present application provides a communication device, comprising: a memory and a processor, the memory being used to store a computer program; the processor being used to enable the communication device to execute any one of the methods described in the above aspects when calling the computer program.

[0068] In a sixth aspect, an embodiment of the present application provides a chip system, which includes a processor coupled to a memory, and the processor executes a computer program stored in the memory to implement any of the methods described in any of the above aspects.

[0069] The chip system may be a single chip or a chip module composed of multiple chips.

[0070] In a seventh aspect, an embodiment of the present application provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the method described in any one of the above aspects is implemented.

[0071] In an eighth aspect, an embodiment of the present application provides a computer program product, which, when executed on a communication device, enables the communication device to execute any one of the methods described in the above aspects.

[0072] It can be understood that the beneficial effects of the fourth to eighth aspects can be found in the relevant descriptions of the first to third aspects, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] FIG1 is a schematic diagram of a communication system provided in an embodiment of the present application.

[0074] FIG2A is a schematic diagram of the structure of the user plane air interface protocol stack provided in an embodiment of the present application.

[0075] FIG2B is a schematic diagram of the structure of the control plane air interface protocol stack provided in an embodiment of the present application.

[0076] FIG3 is a schematic diagram of the transition of the RRC state provided in an embodiment of the present application.

[0077] FIG4 is a schematic diagram of a communication method provided in an embodiment of the present application.

[0078] FIG5 is a schematic diagram of another communication method provided in an embodiment of the present application.

[0079] FIG6 is a schematic diagram of another communication method provided in an embodiment of the present application.

[0080] FIG7 is a schematic diagram of another communication method provided in an embodiment of the present application.

[0081] FIG8 is a schematic block diagram of a communication device provided in an embodiment of the present application.

[0082] FIG9 is a schematic block diagram of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0083] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0084] It should be understood that the methods, situations, categories and divisions of the embodiments in the present application are only for the convenience of description and should not constitute special limitations. The features of various methods, categories, situations and embodiments can be combined without contradiction.

[0085] It should also be understood that the terms "first," "second," and "third" in the embodiments of this application are for distinction only and should not constitute any limitation on this application. It should also be understood that in the various embodiments of this application, the order of the sequence numbers of the processes does not imply a specific order of execution. The order of execution of the processes should be determined by their functions and inherent logic, and should not constitute any limitation on the implementation of the embodiments of this application.

[0086] In the embodiments of the present application, the number of nouns, unless otherwise specified, means "singular noun or plural noun", that is, "one or more". "At least one" means one or more, and "plural" means two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. For example, A / B means: A or B. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c means: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, c can be single or multiple.

[0087] Furthermore, the terms "including," "having," and any variations thereof, as used in the description of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not limited to the listed steps or units but may optionally include other steps or units not listed, or may optionally include other steps or units inherent to the process, method, product, or apparatus.

[0088] It should be noted that in the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0089] The methods and devices provided in the embodiments of the present application are based on the same or similar technical concepts. Since the principles of solving problems by the methods and devices are similar, the implementation of the devices and methods can refer to each other, and the repeated parts will not be repeated.

[0090] FIG1 is a schematic diagram of a communication system 100 provided in an embodiment of the present application. The wireless communication device may include a network device 110 and two or more terminal devices. FIG1 takes a terminal device 120 and a terminal device 130 as an example. The terminal device 130 cannot communicate directly with the network device 110, but the terminal device 120 and the terminal device 130 can communicate directly with each other. Therefore, the terminal device 120 can act as a relay terminal device of the terminal device 130 to realize communication between the terminal device 130 and the network device 110. The terminal device 130 may also be referred to as a remote terminal device (remote UE), and the terminal device 120 may be referred to as a relay terminal device (relay UE). The link in which the terminal device 120 sends data to the network device 110 is called an uplink, and the link in which the terminal device 120 receives data sent by the network device 110 is called a downlink. The embodiments of the present application do not limit the types and quantities of the network devices and terminal devices included in the mobile communication system. The communication interface between the terminal device 120 and the network device 110 may also be referred to as a Uu interface. The communication link between terminal device 120 and terminal device 130 is called a sidelink. The communication interface between terminal device 120 and terminal device 130 may be a PC5 interface. For example, terminal device 120 may send data to terminal device 130 via the sidelink, and terminal device 130 may send data to terminal device 120 via the sidelink. Sidelinks are generally used in scenarios where direct communication between devices is possible, such as vehicle-to-everything (V2X) or device-to-device (D2D). V2X communication can be considered a special case of D2D communication.

[0091] New radio (NR) access technology is currently a mainstream wireless communication technology. It supports V2X communication with lower latency and higher reliability, tailored to the characteristics of V2X services and new service requirements. V2X is a foundational and key technology for realizing smart cars, autonomous driving, and intelligent transportation systems. V2X can include vehicle-to-network (V2N), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), and vehicle-to-pedestrian (V2P). V2N communication is currently the most widely used form of connected vehicle. Its main function is to connect vehicles to cloud servers via mobile networks, providing navigation, entertainment, anti-theft, and other applications. V2V communication can be used for information exchange and alerts between vehicles, with the most typical application being vehicle-to-vehicle collision avoidance safety systems. Through V2I communication, vehicles can communicate with roads and even other infrastructure, such as traffic lights and roadblocks, to obtain road management information such as traffic light signal timing. V2P communication can be used to provide safety warnings to pedestrians and non-motorized vehicles on the road.

[0092] The terminal device 120 or the terminal device 130 in the mobile communication system 100 may also be referred to as a terminal, user equipment (UE), mobile station (MS), mobile terminal (MT), road side unit (RSU), etc. The terminal device in the embodiment of the present application can be a mobile phone, a tablet computer, a computer with wireless transceiver function, a wearable device, a vehicle, a drone, a helicopter, an airplane, a ship, a robot, a robotic arm, a smart home device, a speaker, etc., and can also be a wireless terminal used in scenarios such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IOT), virtual reality (VR), augmented reality (AR), industrial control, self-driving, remote medical, smart grid, transportation safety, smart city, smart wear, smart transportation, and smart home. In this application, the aforementioned terminal devices and chips that can be applied to the aforementioned terminal devices are collectively referred to as terminal devices. It should be understood that the embodiments of the present application do not limit the specific technology and specific device form adopted by the terminal devices.

[0093] In the embodiment of the present application, the network device 110 may be a device in a wireless network, and the network device 110 may also be referred to as a network apparatus. For example, the network device 110 may be a radio access network (RAN) node that connects a terminal device to a wireless network, and may also be referred to as an access network device. The network device 110 includes, but is not limited to, an evolved Node B (eNB), a radio network controller (RNC), a Node B (NB), a base station controller (BSC), a base transceiver station (BTS), a home base station (e.g., a home evolved Node B, or home Node B, HNB), a baseband unit (BBU), an access point (AP) in a wireless fidelity (WIFI) system, a wireless relay node, a wireless backhaul node, a transmission point (TP), a reception point (RP), or a transmission and reception point (TRP), and may also be a network device in a 5G mobile communication system or a network device in other future network systems. For example, a next generation NodeB (gNB) or a transmission reception point (TRP) or TP in an NR system; or one or a group of antenna panels (including multiple antenna panels) of a base station in a 5G mobile communication system; or the network device 110 may also be a network node constituting a gNB or a transmission point, such as a BBU or a distributed unit (DU).

[0094] In some deployments, the network device 110 may include a centralized unit (CU) and a DU. The network device 110 may also include an active antenna unit (AAU). The CU implements some of the functions of the gNB, and the DU implements some of the functions of the gNB. For example, the CU is responsible for processing non-real-time protocols and services and implementing the functions of the radio resource control (RRC) layer. The DU is responsible for processing physical layer protocols and real-time services and implementing the functions of the radio link control (RLC) layer, the media access control (MAC) layer, and the physical (PHY) layer. In some deployments, the CU can also be divided into a centralized unit control plane (CU-CP) node and a centralized unit user plane (CU-UP) node. The CU-CP is responsible for the control plane functions, and the CU-UP is responsible for the user plane functions.

[0095] The communication system 100 shown in FIG1 may apply 4G, 5G, 6G or future communication systems, etc., and the embodiments of the present application are not limited thereto.

[0096] It should be understood that FIG1 is only for ease of understanding, and schematically shows the terminal device 120 or the terminal device 130, but this should not constitute any limitation to the present application. The wireless communication system may also not include the network device 110, or include a greater number of network devices, or may include a greater or fewer number of terminal devices. The present application does not limit this. For example, the terminal device 120 can serve as a relay device for one or more remote terminal devices. In this case, the terminal device 120 can be connected to one or more terminal devices.

[0097] In the following embodiments, the relay terminal device may be the terminal device 120 in FIG. 1 , and the remote terminal device may be the terminal device 130 in FIG. 1 .

[0098] For the convenience of description, the device numbers are omitted below. For example, “terminal device” refers to “terminal device 120” and “network device” refers to “network device 110”.

[0099] Figure 2A shows a schematic diagram of the structure of a user plane air interface protocol stack in a relay scenario provided by an embodiment of the present application. As shown in Figure 2A, the user plane air interface protocol stack includes but is not limited to the Uu-service data adaptation protocol (SDAP), the Uu-packet data convergence protocol (PDCP) layer, the Uu-sidelink relay adaptation protocol (SRAP) layer, the Uu-RLC layer, the Uu-MAC layer and the Uu-PHY layer, the PC5-SRAP layer, the PC5-RLC layer, the PC5-MAC layer and the PC5-PHY layer. The SDAP layer is used to map quality of service (QoS) to data radio bearers (DRBs).

[0100] Figure 2B shows a schematic diagram of the structure of the control plane air interface protocol stack in a relay scenario provided by an embodiment of the present application. As shown in Figure 2B, the control plane air interface protocol stack includes but is not limited to the Uu-radio resource control (RRC) layer, Uu-PDCP layer, Uu-SRAP layer, Uu-RLC layer, Uu-MAC layer, Uu-PHY layer, PC5-SRAP layer, PC5-RLC layer, PC5-MAC layer, and PC5-PHY layer. The RRC layer is used for control plane management.

[0101] The Uu-PDCP layer can process RRC messages on the control plane or data on the user plane. The Uu-PDCP layer can perform IP packet header compression to reduce the number of bits transmitted on the radio interface. The Uu-PDCP layer is also responsible for encryption of the control plane and integrity protection of transmitted data. At the receiving end, the Uu-PDCP layer performs the corresponding decryption and decompression operations. A PDCP entity can be configured for each radio bearer. The PC5-SRAP layer is used to store the mapping relationship between radio bearers (RBs) and PC5 relay RLC channel identifiers, where the PC5 relay RLC channel is used for remote terminal devices or relay terminal devices to transmit small packet data between remote terminal devices and network devices. The Uu-SRAP layer is used to store the mapping relationship between RBs and Uu relay RLC channel identifiers, where the Uu relay RLC channel is used for relay terminal devices to transmit small packet data between remote terminal devices and network devices. The Uu-RLC layer or PC5-RLC layer is responsible for segmentation / concatenation, retransmission control, and duplicate detection, and can be configured with an RLC entity for each radio bearer. The PC5-MAC layer or the Uu-MAC layer controls logical channel multiplexing, hybrid automatic repeat request retransmissions, uplink and downlink scheduling, etc. The PC5-MAC layer provides services to the PC5-RLC layer in the form of logical channels, and the Uu-MAC layer provides services to the Uu-RLC layer in the form of logical channels. The PC5-PHY layer or the Uu-PHY layer manages encoding / decoding, modulation / demodulation, multi-antenna mapping, and other types of physical layer functions. The PC5-PHY layer provides services to the PC5-MAC layer in the form of transport channels, and the Uu-PHY layer provides services to the Uu-MAC layer in the form of transport channels.

[0102] As shown in Figures 2A and 2B, the PC5-MAC layer can provide services to higher layers (such as the PC5-RLC layer) via logical channels (logical channels, LCH), and the Uu-MAC layer can provide services to higher layers (such as the Uu-RLC layer) via logical channels (logical channels, LCH). Depending on the type of information transmitted, logical channels can be classified into control channels for transmitting control information on the control plane and traffic channels for transmitting user data on the user plane. That is, in Figure 2A, the logical channel between the PC5-MAC layer and the PC5-RLC layer can be called a traffic channel, and the Uu-MAC layer and the PC5-RLC layer can be called a traffic channel. In Figure 2B, the logical channel between the PC5-MAC layer and the PC5-RLC layer can be called a control channel, and the logical channel between the Uu-MAC layer and the Uu-RLC layer can be called a control channel. Among them, control channels can include but are not limited to common control channels (CCCH) and dedicated control channels (DCCH). Traffic channels can include but are not limited to dedicated traffic channels (DTCH). CCCH can exist all the time, and terminal devices that do not have an RRC connection with the network device can also use CCCH to transmit information. DCCH can be used to transmit dedicated control information between the terminal device and the network device. DTCH can be used to transmit user data between the terminal device and the network device. Generally, DCCH and DTCH do not exist all the time, but can only be used for communication between the terminal device and the network device after the network device connected to the terminal device restores the terminal device context (terminal device context). Among them, the terminal device context includes but is not limited to the terminal device identification, radio bearer (RB) related configuration, security encryption related configuration, quality of service related configuration, etc.

[0103] At the RRC layer, a terminal device generally has three states: RRC connected (RRC_CONNECTED), RRC idle (RRC_IDLE), and RRC inactive (RRC_INACTIVE). These three states are explained below.

[0104] RRC connected state

[0105] If the terminal device establishes an RRC connection with the network device, the terminal device is in the RRC connected state. In the RRC connected state, the terminal device can establish a user plane and control plane connection with the network device; the network device and the terminal device also save the context of the terminal device's access stratum (AS); the network device can know the cell to which the terminal device belongs; the terminal device can receive data sent by the network device, and the terminal device can also send data to the network device; the terminal device can measure the channel between the terminal device and the network device, and can report the measurement results to the network device. The network device can determine whether to switch the cell to which the terminal device belongs based on the measurement results. In other words, in the RRC connected state, the terminal device and the network device can not only transmit data normally, but the network device can also manage the terminal device.

[0106] RRC idle state

[0107] If the terminal device has not established an RRC connection with the network device, the terminal device is in the RRC idle state. In the RRC idle state, the terminal device can select a PLMN, receive system messages broadcast by the network device, reselect a cell, and receive paging messages.

[0108] RRC inactive state

[0109] After the terminal device establishes an RRC connection with the network device, the terminal device enters the RRC connected state. If the terminal device has no data transmission needs with the network device within the preset time period in the RRC connected state, the network device can determine that the terminal device has entered the RRC inactive state, and the network device can send an RRC release (RRCRelease with suspend indication) message carrying a suspension indication to the terminal device. After the terminal device receives the RRCRelease with suspend indication message, the terminal device retains its own context and enters the RRC inactive state. In the RRC_INACTIVE state, the terminal device can save the context information of the terminal device and only temporarily disconnect the RRC connection with the network device. When the terminal device has data to transmit, the terminal device can send an RRC recovery request message to the network device.

[0110] Among them, the above three states at the RRC layer can be converted to each other. As shown in Figure 3, when the terminal device is in the RRC connected state, the network device can send an RRC release message to the terminal device, and the terminal device can release the RRC connection between it and the network device and enter the RRC idle state. When the terminal device is in the RRC idle state, it can send an RRC establishment request message to the network device, and the network device can establish an RRC connection with the terminal device based on the RRC establishment request message, so that the terminal device can enter the RRC connected state. When the terminal device is in the RRC connected state, the network device can send an RRC release (RRC release with suspend indication) message carrying a suspension indication to the terminal device. After receiving the RRC release with suspend indication message, the terminal device enters the RRC inactive state. When the terminal device is in the RRC inactive state, if there is data to be transmitted, the terminal device may send an RRC resume request message to the network device, and the network device may send an RRC resume response message to the terminal device. After receiving the resume response message, the terminal device may send an RRC resume complete message to the network device, and the terminal device enters the RRC connected state and resumes using the context of the terminal device. It can be understood that the speed of the terminal device entering the RRC connected state from the RRC inactive state is faster than entering the RRC connected state from the RRC idle state. If the terminal device is in the RRC inactive state, the network device may send an RRC release message to the terminal device, and the terminal device enters the RRC idle state.

[0111] When a terminal device needs to transmit data to a network device in an RRC inactive state, the terminal device may send an RRC resume request message to the network device, and the network device may send an RRC resume response message to the terminal device. After receiving the RRC resume response message, the terminal device may send an RRC resume completion message to the network device, and the terminal device enters an RRC connected state. In some scenarios, the data that the terminal device needs to transmit to the network device in the RRC inactive state is very small, and these data are called small data or small packet data. For example, small data or small packet data may include instant messages from the terminal device's application (APP), heartbeat packets from the APP, or push messages from the APP; for another example, small data or small packet data may include: periodic data from a wearable device, business data from an IoT device, etc. The signaling overhead of the terminal device entering the RRC connected state from the RRC inactive state is even greater than the overhead of transmitting these small data itself. Therefore, the terminal device may incur excessive overhead in order to transmit very small data. Especially in relay scenarios, if a remote terminal device needs to transmit small data packets, the remote terminal device needs to enter the RRC connected state to transmit the small data packets. If the relay terminal device needs to forward data for the remote terminal device and also enter the RRC connected state, the signaling overhead of entering the RRC connected state will be greater. Therefore, in relay scenarios, how the relay terminal device transmits small data packets to the remote terminal device in the RRC idle state or RRC inactive state (hereinafter collectively referred to as the RRC non-connected state) is an urgent problem to be solved.

[0112] The terminal device in the definition of the three connection states of the RRC layer above can be a relay terminal device or a remote terminal device. It should be noted that in the relay scenario, the three connection states of the RRC layer can be understood as the RRC connection state between the relay terminal device and the network device, or the RRC connection state between the remote terminal device and the network device.

[0113] In an embodiment of the present application, small data or small packet data needs to meet at least one of the following conditions: the data volume is less than or equal to a preset threshold value, and the data comes from a small data transmission (SDT) SRB or SDT DRB. For example, the preset threshold value can be 500 bytes, 300 bytes, etc. Optionally, the network device and the terminal device can also determine whether the data is small data or small packet data based on the data label or data type, wherein the network device and the terminal device can also negotiate the data label or data type according to the size of the data. For example, the data label can include a label for big data or a label for small data; for another example, data whose data type is a heartbeat packet, an instant message, or periodic data is small data, and data whose data type is a file, video, or audio is big data.

[0114] In an embodiment of the present application, the remote terminal device can save the first context of the small packet data transmitted between the remote terminal device and the network device. If the transmission conditions of the small packet data are met, the remote terminal device can restore the first context and transmit the first small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state based on the restored first context, thereby avoiding the need for the remote terminal device to enter the RRC connected state to transmit the first small packet data between the remote terminal device and the network device.

[0115] The communication method according to an embodiment of the present application is described below with reference to FIG4 . As shown in FIG4 , the communication method 400 includes:

[0116] S410: The remote terminal device saves a first context for transmitting packet data between the remote terminal device and the network device through the relay terminal device.

[0117] Optionally, the first context includes first configuration information of a PC5 relay RLC channel of the remote terminal device and / or a PC5SRAP configuration, wherein the PC5SRAP configuration may include a correspondence between an identifier of the PC5 relay RLC channel and an RB.

[0118] Optionally, the first configuration information may include configuration information of a PC5 relay RLC channel used when the relay terminal device sends information to the remote terminal device, and / or configuration information of a PC5 relay RLC channel used when the remote terminal device sends information to the relay terminal device.

[0119] In one implementation, before S410, the remote terminal device may receive indication information 1, where indication information 1 is used to indicate information related to packet data of the remote terminal device. Optionally, the remote terminal device saves a first context related to packet data transmission based on indication information 1. Optionally, the network device may send a first RRC response message to the remote terminal device via the relay terminal device, where the first RRC response message includes indication information 1. The first context related to packet data transmission saved by the remote terminal device based on indication information 1 may include: first configuration information of the PC5 relay RLC channel corresponding to the identifier of the PC5 relay RLC channel, a PC5SRAP configuration, or at least one of indication information 1.

[0120] It should be understood that the embodiment of the present application does not limit the function of indication information 1. For example, indication information 1 is used to indicate the SDT information of the remote terminal device, or indication information 1 is used to instruct the remote terminal device to save the relay-related SDT context, etc.

[0121] Optionally, indication information 1 is used to indicate information about a PC5 relay RLC channel for transmitting small packet data of a remote terminal device, or information about a PC5 relay RLC channel for small data transmission (SDT) of the remote terminal device, or information about a PC5 relay RLC channel for an SDT radio bearer (RB) of the remote terminal device, or information about a PC5 relay RLC channel corresponding to an SDT RB of the remote terminal device. The information about the PC5 relay RLC channel is used to identify the PC5 relay RLC channel. Optionally, the information about the PC5 relay RLC channel may be an identifier of the PC5 relay RLC channel, and indication information 1 may indicate an identifier of a PC5 relay RLC channel for transmitting small packet data of the remote terminal device, or an identifier of an SDT relay RLC channel for the remote terminal device, or an identifier of a PC5 relay RLC channel for an SDT RB of the remote terminal device, or an identifier of a PC5 relay RLC channel corresponding to an SDT RB of the remote terminal device. Optionally, the indication information 1 may indicate the identifiers of one or more PC5 relay RLC channels. For example, the indication information 1 may indicate a first list, and the first list includes the identifiers of one or more PC5 relay RLC channels.

[0122] In the second implementation, before S410, the remote terminal device may be in an RRC connected state or an RRC inactive state. The network device may send an RRC release message through the relay terminal device. The RRC release message may include a pause indication. The RRC release message may release the RRC connection between the remote terminal device and the network device, and the remote terminal device enters the RRC inactive state according to the pause indication in the RRC release message. Optionally, the remote terminal device may save a first context for transmitting small packet data between the remote terminal device and the network device through the relay terminal device according to the pause indication in the RRC release message. Optionally, the first RRC response message may be an RRC release message, that is, the first RRC response message may include a pause indication, and the remote terminal device may save a first context for transmitting small packet data between the remote terminal device and the network device through the relay terminal device according to the pause indication. Optionally, the remote terminal device may save the context of the remote terminal device based on the pause indication in the RRC release message. The context of the remote terminal device may include a Uu-related context and a first context for transmitting packet data between the remote terminal device and the network device through the relay terminal device. In other words, the pause indication in the RRC release message may trigger the remote terminal device to save the context. The remote terminal device may save the Uu-related context and the first context for transmitting packet data between the remote terminal device and the network device through the relay terminal device. Optionally, the Uu-related context may include: at least one of an RLC configuration, a PDCP configuration, or an SDAP configuration. The remote terminal device may use the Uu-related context during data transmission between the relay terminal device and the network device.

[0123] In a third implementation, before S410, the remote terminal device may be in an RRC connected state or an RRC inactive state. The network device may send an RRC release message to the remote terminal device through the relay terminal device. The RRC release message may include a suspension indication and indication information 1. The RRC release message may release the RRC connection between the remote terminal device and the network device, and the remote terminal device enters the RRC inactive state according to the suspension indication in the RRC release message. Optionally, the first RRC response message may be an RRC release message, that is, the first RRC response message may include a suspension indication and indication information 1. Optionally, the remote terminal device may save a first context for transmitting packet data between the remote terminal device and the network device through the relay terminal device according to the suspension indication and / or indication information 1 in the first RRC response message.

[0124] In the above three implementations, optionally, if the first RRC response message is an RRC release message, the RRC release message includes indication information 1, and the first context may also include indication information 1.

[0125] Optionally, the first context is a context for the remote terminal device to execute services related to packet data.

[0126] Optionally, the remote terminal device may maintain a connection with the relay terminal device, such as maintaining a PC5-S connection or a PC5-RRC connection. Alternatively, the remote terminal device may not be connected to the relay terminal device.

[0127] Optionally, if a connection between the relay terminal device and the remote terminal device (such as a PC5-RRC connection or a PC5-S connection) exists, the remote terminal device can save the first context; if the connection between the relay terminal device and the remote terminal device is disconnected or released, the remote terminal device can delete or release the first context.

[0128] S420: If the transmission conditions of the small packet data are met, the remote terminal device restores the first context.

[0129] Optionally, S420 includes: if the remote terminal device has a small packet data transmission requirement and the small packet data transmission conditions are met, then the first context may be restored. Optionally, if small packet data arrives at the remote terminal device, it indicates a small packet data transmission requirement, or if the remote terminal device receives a paging message for small packet data transmission, it indicates a small packet data transmission requirement. Optionally, the paging message for small packet data may be understood as a paging message related to the small packet data, or a paging message carrying small packet data transmission indication information.

[0130] Optionally, if the remote terminal device saves the first context according to the indication information 1 , the remote terminal device may restore the first context according to the indication information 1 .

[0131] Optionally, if the remote terminal device has saved the first context used for transmitting packet data between the remote terminal device and the network device through the relay terminal device according to the suspension indication in the RRC release message, the remote terminal device may restore the first context. Optionally, the RRC release message may not include indication information 1. In this case, the remote terminal device may restore the context of the remote terminal device. For example, the context of the remote terminal device includes the first context used for transmitting packet data between the remote terminal device and the network device through the relay terminal device and the Uu-related context, or the remote terminal device may not be able to determine which PC5 and / or Uu relay RLC channels are used for transmitting packet data between the remote terminal device and the network device through the relay terminal device. Therefore, the remote terminal device may determine that the remote terminal device is not supported to transmit packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state.

[0132] Optionally, if the relay terminal device saves the first context for transmitting small packet data between the remote terminal device and the network device according to the pause indication in the RRC release message, if the RRC release message also includes third indication information, the relay terminal device can restore the first context for transmitting small packet data between the remote terminal device and the network device according to the third indication information.

[0133] The following describes the transmission conditions of small packet data in different situations.

[0134] In case one, the upper layer of the remote terminal device requests RRC connection recovery, such as the application layer or non-access stratum (NAS) requests RRC connection recovery, which means that the remote terminal device currently has a transmission requirement, such as the transmission requirement of uplink data or uplink signaling. That is to say, when the first packet data of the remote terminal device arrives, the upper layer will trigger or request the RRC layer to restore the RRC connection, the remote terminal device executes the RRC connection recovery process, and the remote terminal device will also send an RRC request message to the relay terminal device. It can be understood that case one can be used for the situation where the remote terminal device has an uplink data transmission requirement. When the remote terminal device has an uplink data transmission requirement, the remote terminal device needs to judge the conditions corresponding to case one.

[0135] In the second scenario, the remote terminal device receives a paging message for small packet data. Specifically, the remote terminal device may receive the paging message for small packet data via a relay terminal device. For example, the remote terminal device receives a paging message related to small packet data forwarded by the relay terminal device. When the remote terminal device receives the paging message for small packet data, it indicates that the network device has small packet data to send to the remote terminal device. It is understood that the second scenario can be used when the network device has a downlink data transmission requirement related to the remote terminal device. When the network device has a downlink data transmission requirement, the remote terminal device needs to determine the conditions corresponding to the second scenario.

[0136] Case three: the data volume of the first packet data currently arriving at the remote terminal device is less than or equal to the first data volume threshold value. The data volume of the first packet data may include the size of the PC5RLC protocol data unit (PDU) corresponding to the first packet data, and / or the size of the PC5RLC service data unit (SDU) corresponding to the first packet data. For example, the data of the remote terminal device needs to be mapped to the corresponding PC5RLC through SRAP, so the remote terminal device also needs to consider the size of the SRAP header when calculating the data volume. Optionally, the network device can send the first data volume threshold value information, the remote terminal device can receive the first data volume threshold value information, and the first data volume threshold value information can indicate the first data volume threshold value.

[0137] Optionally, the network device sending the first data volume threshold value information may include: the network device broadcasting the first data volume threshold value information.

[0138] It is understandable that situation three can be used when the remote terminal device has an uplink data transmission requirement. When the remote terminal device has an uplink data transmission requirement, the remote terminal device needs to determine the conditions corresponding to situation three.

[0139] Case 4: The RSRP between the remote terminal device and the relay terminal device is greater than or equal to the first RSRP threshold value.

[0140] Optionally, the remote terminal device can measure the RSRP between the remote terminal device and the relay terminal device. If the measured RSRP is greater than or equal to the first RSRP threshold value, it means that the communication quality between the relay terminal device and the remote terminal device is good and the first packet data can be transmitted.

[0141] Optionally, the network device may send first RSRP threshold value information, and the remote terminal device may receive the first RSRP threshold value information, where the first RSRP threshold value information is used to indicate the first RSRP threshold value. Optionally, the network device may send the first RSRP threshold value information, which may include: the network device may broadcast the first RSRP threshold value information. In the event of situation three, if the network device also broadcasts the first data volume threshold value information, the network device may also broadcast the first RSRP threshold value information and the first data volume threshold value information simultaneously.

[0142] Scenario 5: The remote terminal device receives first indication information sent by the network device. The remote terminal device may receive the first indication information, where the first indication information indicates that the network device supports SDT of the remote terminal device or that the network device supports transmission of small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state. Therefore, the remote terminal device may determine that the network device supports transmission of the first small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state.

[0143] Optionally, the first indication information may explicitly indicate that the network device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state. For example, a bit value corresponding to the first indication information is 1, indicating that the network device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state. A bit value corresponding to the first indication information is 0 or the first indication information does not exist, indicating that the network device does not support the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state. Optionally, the first indication information may also implicitly indicate that the network device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state. For example, the network device sends the first timer information to the remote terminal device through the relay terminal device. The first timer information indicates the first duration of the first timer for the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device. The first timer information sent by the network device may be the first indication information. While indicating the first duration, the first timer information also implicitly indicates that the network device also supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state. That is, the network device sends the first timer information, indicating that the network device supports the SDT of the remote terminal device or the network device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state. That is, the first indication information in situation five may be the first timer information. For another example, the first data volume threshold value information sent by the network device may be first indication information, and the first data volume threshold value information is used to indicate the first data volume threshold value. That is, when the transmission conditions include situation three and situation five, the network device may send the first data volume threshold value information. The first data volume threshold value information may indicate the first data volume threshold value and may also implicitly indicate that the network device supports the SDT of the remote terminal device or that the network device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state. For another example, the first RSRP threshold value information sent by the network device may be first indication information, and the first RSRP threshold value information may indicate the first RSRP threshold value. If the network device sends the first RSRP threshold value information, it may implicitly indicate that the network device supports the SDT of the remote terminal device or that the network device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state. Otherwise, the network device will not send the first RSRP threshold value information.That is, when the transmission conditions include Case 4 and Case 5, the first RSRP threshold value information sent by the network device can indicate the first RSRP threshold value and can also implicitly indicate that the network device supports the remote terminal device in the RRC non-connected state, transmitting small packet data between the remote terminal device and the network device through the relay terminal device. In other words, the network device can directly or indirectly indicate whether the network device supports the remote terminal device in the RRC non-connected state, transmitting small packet data between the remote terminal device and the network device through the relay terminal device.

[0144] Optionally, the network device may broadcast the first indication information, and the remote terminal device may receive the first indication information broadcast by the network device.

[0145] It is understandable that in order to support the remote terminal device to transmit small packet data in the RRC non-connected state, the network device also needs to save the first context. Therefore, the network device can inform the remote terminal device in advance whether the network device supports this function or feature, so as to avoid the remote terminal device initiating small packet-related processes while the network device does not support it and wastes signaling overhead and power consumption.

[0146] Optionally, in some scenarios, the first indication information of situation five may not be used as the remote terminal device to determine whether the transmission conditions of the small packet data are met, but the first indication information may trigger the remote terminal device to determine whether the transmission conditions of the small packet data are met. That is to say, in some cases, the remote terminal device determines whether the transmission conditions of the small packet data are met after receiving the first indication information. The first indication information may trigger the remote terminal device to determine whether the transmission conditions of the small packet data are met; in other cases, the remote terminal device may use whether the first indication information is received as whether the transmission conditions of the small packet data are met.

[0147] In case 6, the first small data packet currently arriving at the remote terminal device comes from an SDT RB, such as an SDT DRB or SDT SRB2. Some RBs of the remote terminal device are used to transmit small data packets. If the first small data packet comes from an RB used to transmit SDT, the remote terminal device can determine that the currently arriving first small data packet can be transmitted through the SDT process.

[0148] It is understandable that situation six can be used when the remote terminal device has an uplink data transmission requirement. When the remote terminal device has an uplink data transmission requirement, the remote terminal device needs to determine the conditions corresponding to situation six.

[0149] Optionally, the transmission condition may be one or more of the aforementioned conditions 1 to 6. The embodiment of the present application does not limit the transmission condition, or the transmission condition may also include the aforementioned six conditions. If the remote terminal device determines that the aforementioned transmission conditions are not met, the first context may not be restored.

[0150] Optionally, in S420, the transmission condition may be one or more of the aforementioned situations one to six. The embodiment of the present application does not limit the transmission condition, or the transmission condition may also include the aforementioned six situations. If the remote terminal device determines that the aforementioned transmission condition is not met, it may release the first context, enter the RRC connection state to obtain the second context, and transmit the first packet data between the remote terminal device and the network device according to the second context. That is, the remote terminal device may restore the first context if it determines that the transmission condition is met, and may initiate RRC connection recovery to enter the RRC connection state if the transmission condition is not met, and transmit the first packet data between the remote terminal device and the network device through the relay terminal device in the RRC connection state. Optionally, if the remote terminal device determines that each of the above six situations is not met, it can release the first context and enter the RRC connection state to obtain the second context, and transmit the first packet data between the remote terminal device and the network device through the relay terminal device according to the second context. Correspondingly, in S420, the remote terminal device can determine that any one of the above six situations is met and the first context can be restored; or if it is determined that any one of the above six situations is not met, it can enter the RRC connection state and transmit the first packet data between the remote terminal device and the network device through the relay terminal device. Correspondingly, in S420, the remote terminal device can determine that each of the above six situations is met and the first context can be restored.

[0151] Optionally, S420 further includes: if the transmission condition of the small packet data is met, the remote terminal device sends second indication information, the second indication information being used to indicate that the remote terminal device has a transmission requirement for the small packet data. The following describes a manner in which the remote terminal device sends the second indication information.

[0152] Mode 1, communication method 400 includes: if the transmission conditions of the small packet data are met, the remote terminal device sends a first RRC request message to the network device through the relay terminal device when initiating the transmission process of the small packet data (the first RRC request message can be replaced by the RRC request message of the remote terminal device), the first RRC request message includes second indication information, the second indication information is used to indicate that the remote terminal device has a transmission requirement for the small packet data, for example, the cause value information (such as the recovery reason) included in the first RRC request message can be the second indication information, for example, when the cause value information is the first value, it can represent the SDT of the remote terminal device. Optionally, after receiving the first RRC request message, the relay terminal device may not parse the first RRC request message, and transparently transmit the first RRC request message to the network device, that is, the relay terminal device may not perceive whether the remote terminal device has a transmission requirement for the small packet data.

[0153] Optionally, before the remote terminal device sends the first RRC request message, the remote terminal device may obtain capability information of the relay terminal device, where the capability information is used to indicate whether the relay terminal device supports the transmission of small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state; if the capability information indicates that the relay terminal device supports the transmission of small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state, the remote terminal device sends the first RRC request message to the relay terminal device; if the capability information indicates that the relay terminal device does not support the transmission of small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state, the remote terminal device may not send the first RRC request message.

[0154] Optionally, before the remote terminal device sends the first RRC request message to the network device through the relay terminal device, if the remote terminal device has a connection with the relay terminal device, for example, a PC5-S connection or a PC5-RRC connection, the remote terminal device may send the first RRC request message to the relay terminal device through the PC5-S connection or the PC5-RRC connection. If there is no connection between the remote terminal device and the relay terminal device, the remote terminal device may discover a relay terminal device and, after establishing a connection with the relay terminal device, send the first RRC request message to the relay terminal device.

[0155] Optionally, the relay terminal device may be in an RRC connected state, or an RRC idle state or an RRC inactive state. If the relay terminal device is in an RRC connected state, the relay terminal device may send a first RRC request message to the network device through the RRC connection. If the relay terminal device is in an RRC idle state, the relay terminal device may send an RRC establishment request message to the network device to establish an RRC connection between the relay terminal device and the network device, and the relay terminal device may use the established RRC connection to send the first RRC request message to the network device. If the relay terminal device is in an RRC inactive state, the relay terminal device may send an RRC recovery request message to the network device to restore the RRC connection between the relay terminal device and the network device, and the relay terminal device may use the restored RRC connection to send the first RRC request message to the network device. Optionally, the relay terminal device may also remain in the RRC inactive state and send a first RRC request message to the network device. For example, the relay terminal device may use CG-SDT resources or RA-SDT resources to send the RRC recovery request message and the first RRC request message of the relay terminal device, wherein RA-SDT may perform small data transmission (SDT) based on the principle of random access (RA). CG-SDT may perform SDT for pre-configured resources (CG). That is to say, when the relay terminal device forwards the first RRC request message to the network device, it does not limit the RRC state of the relay terminal device. The first RRC request message may trigger the relay terminal device to send a second RRC request message of the relay terminal device (such as an RRC recovery request message or an RRC establishment request message, etc.) to the network device.

[0156] Optionally, the above-mentioned remote terminal device can send a first RRC request message to the network device through the relay terminal device in the initial stage of packet data transmission in the RRC non-connected state.

[0157] Optionally, when the network device receives the first RRC request message, it may learn, based on the second indication information in the first RRC request message, that the remote terminal device has a transmission requirement for small packet data. The network device may send third indication information to the remote terminal device via the relay terminal device, where the third indication information is used to indicate that the network device has successfully received the first RRC request message. Optionally, the relay terminal device may send identification information indicating the remote terminal device to the network device, and the network device may determine, based on the identification information and the second indication information in the first RRC request message, that the remote terminal device identified by the identification information has a transmission requirement for small packet data.

[0158] Alternatively, the third indication information is used to indicate that the initial transmission of the packet data of the remote terminal device is successful, or to indicate that the network device has learned that the remote terminal device has a transmission requirement for packet data, or to indicate confirmation of the first RRC request message, or to trigger the remote terminal device to send the first packet data, etc.

[0159] In some embodiments, the third indication information is included in the MAC layer information. Optionally, the third indication information may correspond to a logical channel identity (LCID), which may be an index or value of an LCID reserved in the protocol, for example, the LCID is any one of 35-46. For another example, the third indication information may correspond to an enhanced logical channel identity (eLCID), which may be an index or value of an eLCID reserved in the protocol, for example, the eLCID is any one of 64-290.

[0160] Optionally, the information of the MAC layer may be a MAC control element (CE). For example, the first MAC CE includes the third indication information. The first MAC CE is identified by an index or value of an LCID, where the LCID may be any reserved value from 35 to 46, or the first MAC CE is identified by an index or value of an eLCID, where the eLCID may be any reserved value from 64 to 290. "Reserved" may also be understood as not being used. The first MAC CE being identified by the LCID may be understood as the MAC subheader corresponding to the first MAC CE including an LCID field, where the value of the LCID field is any value from 35 to 46. The first MAC CE being identified by the eLCID may be understood as the MAC subheader corresponding to the first MAC CE including an eLCID field, where the value of the eLCID field is any value from 64 to 290. For example, if the value of the LCID field in the MAC subheader corresponding to the first MAC CE is any one of 35-46, or the value of the eLCID field is any one of 64-290, it indicates that the network device sends the third indication information. The first MAC CE including the third indication information may include the following multiple situations: for example, the first MAC CE includes a first bit, and if the value of the first bit is 1, it indicates that the network device sends the third indication information; if the value of the first bit is 0, it indicates that the network device does not send the third indication information; or, if the value of the first bit is 0, it indicates that the network device sends the third indication information; if the value of the first bit is 1, it indicates that the network device does not send the third indication information. Optionally, the first MAC CE may only include the MAC subheader corresponding to the first MAC CE, and does not include the MAC CE body.

[0161] Optionally, the information of the MAC layer may be a MAC subheader. For example, the reserved bit field in the first MAC subheader may indicate the third indication information. For example, if the value of the reserved bit is 1, it indicates that the network device sends the third indication information. If the value of the reserved bit is 0, it indicates that the network device does not send the third indication information. Alternatively, if the value of the reserved bit is 0, it indicates that the network device sends the third indication information. If the value of the reserved bit is 1, it indicates that the network device does not send the third indication information. For another example, the LCID or eLCID field included in the first MAC subheader may indicate the third indication information. For example, if the value of the LCID field is any one of 35-46, or if the value of the eLCID field is any one of 64-290, it indicates that the network device sends the third indication information.

[0162] In some embodiments, the third indication information is included in the information of the SRAP layer. Optionally, the information of the SRAP layer may be an SRAP subheader or an SRAP PDU. Optionally, the SRAP subheader includes a reserved bit, and the third indication information may be the reserved bit. Optionally, the SRAP PDU may be an SRAP control PDU or an SRAP data PDU. For example, a value of 1 for the reserved bit in the SRAP subheader indicates that the network device has successfully received the first RRC request message, and a value of 0 for the reserved bit in the SRAP layer information indicates that the network device has not received the first RRC request message. For another example, a value of 1 for the bit corresponding to the third indication information in the SRAP PDU indicates that the network device has successfully received the first RRC request message, and a value of 0 or absence of the bit corresponding to the third indication information in the SRAP PDU indicates that the network device has not received the first RRC request message.

[0163] In some embodiments, the third indication information is included in the information of the RRC layer. For example, if the bit corresponding to the third indication information in the RRC layer information is 1, it indicates that the network device has successfully received the first RRC request message. If the bit corresponding to the third indication information in the RRC layer information is 0 or the third indication information does not exist in the RRC layer information, it indicates that the network device has not received the first RRC request message. Optionally, the RRC layer information including the third indication information will not transfer the remote terminal device to the RRC connection state. For example, the first RRC message includes the third indication information, and the first RRC message may be a new message not defined in the protocol.

[0164] Optionally, when the network device receives the first RRC request message, it may be informed, based on the second indication information in the first RRC request message, that the remote terminal device has a transmission requirement for small packet data. After the relay terminal device confirms that the network device has received the first RRC request message, the relay terminal device may send fourth indication information to the remote terminal device, where the fourth indication information is used to indicate that the network device has successfully received the first RRC request message. Optionally, the network device may indicate to the relay terminal device that the first RRC request message has been successfully received, so that the relay terminal device may confirm that the network device has received the first RRC request message and then send the fourth indication information to the remote terminal device.

[0165] In some embodiments, the fourth indication information may be included in the MAC layer information. Optionally, the fourth indication information in the MAC layer information may correspond to a logical channel identity (LCID), which may be an index or value of an LCID reserved in the protocol, for example, the LCID is any one of 20-55, or for another example, the fourth indication information may correspond to an enhanced logical channel identity (eLCID), which may be an index or value of an eLCID reserved in the protocol.

[0166] Optionally, the information of the MAC layer may be a MAC control element (CE). For example, the second MAC CE includes the fourth indication information. The second MAC CE is identified by an index or value of an LCID, where the LCID may be any reserved value from 20 to 55, or the second MAC CE is identified by an index or value of an eLCID, where the eLCID may be any reserved value. "Reserved" may also be understood as meaning unused. The second MAC CE being identified by the LCID may be understood as meaning that the MAC subheader corresponding to the second MAC CE includes an LCID field, where the value of the LCID field is any reserved value from 20 to 55. The second MAC CE being identified by the eLCID may be understood as meaning that the MAC subheader corresponding to the second MAC CE includes an eLCID field, where the value of the eLCID field is any reserved value. For example, if the value of the LCID field in the MAC subheader corresponding to the second MAC CE is any value from 20 to 55, or the value of the eLCID field is any reserved value, it indicates that the relay terminal device sends the fourth indication information. Among them, the second MAC CE including the fourth indication information may include the following multiple situations: for example, the second MAC CE includes a second bit, and if the second bit is 1, it indicates that the relay terminal device sends the fourth indication information; if the second bit is 0, it indicates that the relay terminal device does not send the fourth indication information; or, if the second bit is 0, it indicates that the relay terminal device sends the fourth indication information; if the second bit is 1, it indicates that the relay terminal device does not send the fourth indication information. Optionally, the second MAC CE may only include the MAC subheader corresponding to the second MAC CE, and does not include the MAC CE body.

[0167] Optionally, the information of the MAC layer is a MAC subheader. For example, the reserved bit field in the second MAC subheader can indicate the fourth indication information. For example, if the value of the reserved bit is 1, it indicates that the relay terminal device sends the fourth indication information. If the value of the reserved bit is 0, it indicates that the relay terminal device does not send the fourth indication information. Alternatively, if the value of the reserved bit is 0, it indicates that the relay terminal device sends the fourth indication information. If the value of the reserved bit is 1, it indicates that the relay terminal device does not send the fourth indication information. For another example, the LCID or eLCID field included in the second MAC subheader can indicate the fourth indication information. For example, if the value of the LCID field is any one of 20-55, or if the value of the eLCID field is any one of the reserved values, it indicates that the relay terminal device sends the fourth indication information.

[0168] In some embodiments, the fourth indication information may be included in the information of the SRAP layer. Optionally, the information of the SRAP layer may be an SRAP subheader or an SRAP PDU. Optionally, the SRAP subheader includes a reserved bit, and the fourth indication information may be the reserved bit. Optionally, the SRAP PDU may be an SRAP control PDU or an SRAP data PDU. For example, a value of 1 for the reserved bit in the SRAP subheader indicates that the network device has successfully received the first RRC request message, a value of 0 for the reserved bit in the SRAP subheader or the absence of the fourth indication information in the SRAP layer information indicates that the network device has not received the first RRC request message. For another example, a value of 1 for the bit corresponding to the fourth indication information in the SRAP PDU indicates that the network device has successfully received the first RRC request message, a value of 0 or the absence of the bit corresponding to the fourth indication information in the SRAP PDU indicates that the network device has not received the first RRC request message.

[0169] Mode 2, the communication method 400 includes: if the transmission conditions of the small packet data are met, the remote terminal device can send second indication information to the relay terminal device, and the second indication information is used to indicate that the remote terminal device has a transmission demand for the small packet data.

[0170] In some embodiments, the second indication information may be included in the MAC layer information. Optionally, the second indication information may correspond to an LCID, which may be an index or value of an LCID reserved in the protocol, for example, the LCID may be any value from 20 to 55. For another example, the second indication information may correspond to an eLCID, which may be an index or value of an eLCID reserved in the protocol.

[0171] Optionally, the MAC layer information may be a MAC CE. For example, the third MAC CE includes the second indication information. The third MAC CE is identified by an index or value of an LCID, where the LCID may be any value from 20 to 55, or the third MAC CE is identified by an index or value of an eLCID, where the eLCID may be any reserved value. "Reserved" may also be understood as meaning unused. The third MAC CE being identified by the LCID may mean that the MAC subheader corresponding to the third MAC CE includes an LCID field, where the value of the LCID field is any value from 20 to 55, and the third MAC CE being identified by the eLCID may mean that the MAC subheader corresponding to the third MAC CE includes an eLCID field, where the value of the eLCID field is any reserved value. For example, if the value of the LCID field in the MAC subheader corresponding to the third MAC CE is any value from 20 to 55, or the value of the eLCID field is any reserved value, it indicates that the remote terminal device sends the second indication information. Optionally, the third MAC CE including the second indication information may include the following multiple situations: for example, the third MAC CE includes a third bit, and if the third bit is 1, it indicates that the remote terminal device sends the second indication information; if the third bit is 0, it indicates that the remote terminal device does not send the second indication information; or, if the third bit is 0, it indicates that the remote terminal device sends the second indication information; if the third bit is 1, it indicates that the remote terminal device does not send the second indication information. Optionally, the third MAC CE may only include the MAC subheader corresponding to the third MAC CE, and does not include the MAC CE body.

[0172] Optionally, the information of the MAC layer may be a MAC subheader. For example, the reserved bit field in the third MAC subheader may indicate the second indication information. For example, if the value of the reserved bit is 1, it indicates that the remote terminal device has a transmission requirement for small packet data. If the value of the reserved bit is 0, it indicates that the remote terminal device does not have a transmission requirement for small packet data. Alternatively, if the value of the reserved bit is 0, it indicates that the remote terminal device has a transmission requirement for small packet data. If the value of the reserved bit is 1, it indicates that the remote terminal device does not have a transmission requirement for small packet data. For another example, the LCID or eLCID field included in the third MAC subheader may indicate the second indication information. For example, if the value of the LCID field is any one of 20-55, or if the value of the eLCID field is any one of the reserved values, it indicates that the remote terminal device has a transmission requirement for small packet data.

[0173] In some embodiments, the second indication information may be included in the SRAP layer information. Optionally, the SRAP layer information may be an SRAP subheader or an SRAP PDU. For example, the SRAP subheader includes a reserved bit, and the reserved bit indicates the second indication information. For example, the SRAP PDU may be an SRAP control PDU or an SRAP data PDU. For example, if the bit corresponding to the second indication information in the SRAP layer information is 1, it indicates that the remote terminal device has a transmission requirement for small packet data. If the bit corresponding to the second indication information in the SRAP layer information is 0 or the second indication information does not exist in the SRAP layer information, it indicates that the remote terminal device does not have a transmission requirement for small packet data.

[0174] Optionally, in method two, the relay terminal device can perceive that the remote terminal device has a transmission demand for small packet data based on the second indication information, and the relay terminal device can also send a fifth indication information to the network device based on the second indication information, and the fifth indication information is used to indicate that the remote terminal device has a transmission demand for small packet data.

[0175] In some embodiments, the fifth indication information is included in the information of the MAC layer. Optionally, the fifth indication information may correspond to an LCID, which may be an index or value of an LCID reserved in the protocol, for example, the LCID is any one of 37-42 or 47. For another example, the fifth indication information may correspond to an enhanced logical channel identifier (enhanced LCID, eLCID), which may be an index or value of an eLCID reserved in the protocol, for example, the eLCID is any one of 64-292.

[0176] Optionally, the information of the MAC layer may be a MAC control element (CE). For example, the fourth MAC CE includes the fifth indication information. The fourth MAC CE is identified by an index or value of an LCID, where the LCID may be any reserved value from 37 to 42 or 47, or the fourth MAC CE is identified by an index or value of an eLCID, where the eLCID may be any reserved value from 64 to 292. "Reserved" may also be understood as not being used. The fourth MAC CE being identified by the LCID may be understood as the MAC subheader corresponding to the fourth MAC CE including an LCID field, where the value of the LCID field is any value from 37 to 42 or 47. The fourth MAC CE being identified by the eLCID may be understood as the MAC subheader corresponding to the fourth MAC CE including an eLCID field, where the value of the eLCID field is any value from 64 to 292. For example, if the value of the LCID field in the MAC subheader corresponding to the fourth MAC CE is any one of 37-42 or 47, or the value of the eLCID field is any one of 64-292, it indicates that the remote terminal device has a transmission requirement for small packet data. The fourth MAC CE including the fifth indication information may include the following multiple situations: for example, the fourth MAC CE includes a third bit, and if the fourth bit is 1, it indicates that the remote terminal device has a transmission requirement for small packet data, and if the fourth bit is 0, it indicates that the remote terminal device does not have a transmission requirement for small packet data; or, if the fourth bit is 0, it indicates that the remote terminal device has a transmission requirement for small packet data, and if the fourth bit is 1, it indicates that the remote terminal device does not have a transmission requirement for small packet data.

[0177] Optionally, the information of the MAC layer is a MAC subheader. For example, the reserved bit field in the fourth MAC subheader can indicate the fifth indication information. For example, if the value of the reserved bit is 1, it indicates that the remote terminal device has a transmission requirement for small packet data. If the value of the reserved bit is 0, it indicates that the remote terminal device does not have a transmission requirement for small packet data. Alternatively, if the value of the reserved bit is 0, it indicates that the remote terminal device has a transmission requirement for small packet data. If the value of the reserved bit is 1, it indicates that the remote terminal device does not have a transmission requirement for small packet data. For another example, the LCID or eLCID field included in the fourth MAC subheader can indicate the fifth indication information. For example, if the value of the LCID field is any one of 37-42 or 47, or if the value of the eLCID field is any one of 64-292, it indicates that the remote terminal device has a transmission requirement for small packet data.

[0178] In some embodiments, the fifth indication information is included in the information of the SRAP layer. Optionally, the information of the SRAP layer may be an SRAP subheader or an SRAP PDU. Optionally, the SRAP subheader includes a reserved bit, and the fifth indication information may be the reserved bit. Optionally, the SRAP PDU may be an SRAP control PDU or an SRAP data PDU. For example, a value of 1 for the reserved bit in the SRAP subheader indicates that the remote terminal device has a transmission requirement for small packet data, a value of 0 for the reserved bit in the SRAP subheader or the absence of the fifth indication information in the SRAP layer information indicates that the remote terminal device does not have a transmission requirement for small packet data. For another example, a value of 1 for the bit corresponding to the fifth indication information in the SRAP PDU indicates that the remote terminal device has a transmission requirement for small packet data, and a value of 0 or the absence of the bit corresponding to the fifth indication information in the SRAP PDU indicates that the remote terminal device does not have a transmission requirement for small packet data.

[0179] In some embodiments, the fifth indication information is included in the information of the RRC layer. For example, the sidelink terminal information (sidelink UE information) message includes the fifth indication information. For example, the bit value corresponding to the fifth indication information in the sidelink UE information message is 1, indicating that the remote terminal device has a transmission requirement for small packet data, and the bit value corresponding to the fifth indication information in the sidelink UE information message is 0 or the fifth indication information does not exist, indicating that the remote terminal device does not have a transmission requirement for small packet data. For another example, the fifth indication information is included in the cause value information. If the cause value information takes the second value, it indicates that the relay terminal device has sent the fifth indication information.

[0180] Optionally, in method 2, if the transmission conditions for the small packet data are met, the remote terminal device may further send a first RRC request message to the relay terminal device, and the relay terminal device may forward the first RRC request message to the network device. Optionally, the remote terminal device may send the first RRC request message and the second indication information to the relay terminal device simultaneously, or may send the RRC request message and the second indication information separately.

[0181] Optionally, before the remote terminal device sends the first RRC request message, the remote terminal device may obtain the capability information of the relay terminal device, where the capability information is used to indicate whether the relay terminal device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state; if the capability information indicates that the relay terminal device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state, the first RRC request message and / or second indication information are sent to the relay terminal device; if the capability information indicates that the relay terminal device does not support the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state, the remote terminal device may not send the second indication information, and the remote terminal device may only send the first RRC request message to request to enter the RRC connected state to transmit the first small packet data.

[0182] Optionally, before the remote terminal device sends the first RRC request message and / or the second indication information to the network device through the relay terminal device, if the remote terminal device has a connection with the relay terminal device, for example, a PC5-S connection or a PC5-RRC connection, the remote terminal device may send the first RRC request message and / or the second indication information to the relay terminal device through the PC5-S connection or the PC5-RRC connection. If no connection exists between the remote terminal device and the relay terminal device, the remote terminal device may discover a relay terminal device and, after establishing a connection with the relay terminal device, send the first RRC request message and / or the second indication information to the relay terminal device.

[0183] Optionally, the relay terminal device may be in an RRC connected state, or an RRC idle state or an RRC inactive state. If the relay terminal device is in an RRC connected state, the relay terminal device may send a first RRC request message and / or fifth indication information to the network device through the RRC connection. If the relay terminal device is in an RRC idle state, the relay terminal device may send an RRC establishment request message to the network device to establish an RRC connection between the relay terminal device and the network device, and the relay terminal device may use the established RRC connection to send the first RRC request message and / or fifth indication information to the network device. If the relay terminal device is in an RRC inactive state, the relay terminal device may send an RRC recovery request message to the network device to restore the RRC connection between the relay terminal device and the network device, and the relay terminal device may use the restored RRC connection to send the first RRC request message and / or fifth indication information to the network device. Optionally, the relay terminal device may also remain in the RRC inactive state and send the first RRC request message and / or the fifth indication information to the network device. For example, the relay terminal device may use CG-SDT resources or RA-SDT resources to send the RRC recovery request message of the relay terminal device, or may send the first RRC request message and / or the fifth indication information, wherein RA-SDT may be understood as small data transmission (SDT) through random access (RA), for example, the first RRC request message and / or the fifth indication information may be sent through msg3 or msgA of RA-SDT. CG-SDT may be understood as SDT through pre-configured resources (configured grant, CG), for example, the first RRC request message and / or the fifth indication information may be sent using CG-SDT resources. For another example, optionally, the relay terminal device may send the first RRC request message and / or the fifth indication information to the network device through RA resources, for example, the first RRC request message and / or the fifth indication information may be sent through msg3 or msgA. That is to say, when the relay terminal device sends the first RRC request message and / or the fifth indication information to the network device, there is no restriction on the RRC state the relay terminal device is in. The first RRC request message may trigger the relay terminal device to send a second RRC request message (such as an RRC recovery request message or an RRC establishment request message, etc.) of the relay terminal device to the network device.

[0184] Optionally, the above-mentioned remote terminal device can send a first RRC request message and a second indication information to the relay terminal device in the initial stage of packet data transmission in the RRC non-connected state.

[0185] Optionally, if the relay terminal device enters the RRC connected state, after the network device receives the first RRC request message and the fifth indication information, it can determine based on the fifth indication information that the first RRC request message was sent because the remote terminal device has a small packet data transmission requirement, so the network device can send a third indication information to the remote terminal device through the relay terminal device, and the third indication information is used to indicate that the network device has successfully received the first RRC request message. Alternatively, optionally, if the relay terminal device remains in the RRC unconnected state, after the network device receives the first RRC request message, it can determine based on the RA-SDT resources or CG-SDT resources used by the relay terminal device and the first RRC request message that the current remote terminal device has a small packet data transmission requirement, so the network device can send a third indication information to the remote terminal device through the relay terminal device, and the third indication information is used to indicate that the network device has successfully received the first RRC request message. Optionally, the relay terminal device can send identification information indicating the remote terminal device to the network device, and the network device can determine based on the identification information and the fifth indication information that the remote terminal device identified by the identification information has a small packet data transmission requirement. The implementation method of the third indication information can refer to the description of the third indication information in Method 1, which will not be repeated here.

[0186] Alternatively, the third indication information is used to indicate that the initial transmission of the packet data of the remote terminal device is successful, or to indicate that the network device has learned that the remote terminal device has a transmission requirement for packet data, or to indicate confirmation of the first RCC request message, or to trigger the remote terminal device to send the first packet data, etc.

[0187] Optionally, when the network device receives the first RRC request message and the fifth indication information sent by the relay terminal device, it can be informed based on the fifth indication information that the remote terminal device has a transmission requirement for small packet data. After the relay terminal device confirms that the network device has received the first RRC request message, the relay terminal device can send a fourth indication information to the remote terminal device. The fourth indication information is used to indicate that the network device has successfully received the first RRC request message. Optionally, the network device can indicate to the relay terminal device that the first RRC request message has been successfully received, so the relay terminal device can confirm that the network device has received the first RRC request message. The implementation method of the fourth indication information can refer to the description of the fourth indication information in Method 1 and will not be repeated here.

[0188] S430, the remote terminal device transmits the first packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state based on the restored first context.

[0189] Optionally, S430 includes: the remote terminal device may transmit the first packet data to the relay terminal device in the RRC non-connected state based on the restored first context, and the relay terminal device forwards the first packet data to the network device. For uplink transmission, the remote terminal device may send the first packet data to the relay terminal device in the RRC non-connected state based on the restored first context, and the relay terminal device forwards the first packet data to the network device. For downlink transmission, the network device may send the first packet data to the relay terminal device, the relay terminal device may forward the first packet data to the remote terminal device, and the remote terminal device may receive the first packet data in the RRC non-connected state based on the restored first context.

[0190] Optionally, the remote terminal device may send a first packet of data to the relay terminal device in an RRC non-connected state based on the restored first context, including: the remote terminal device may send the first packet of data to the relay terminal device based on the first configuration information and / or PC5SRAP configuration of the PC5 relay RLC channel corresponding to the identifier of the PC5 relay RLC channel included in the first context. Optionally, if the first packet of data arrives on a certain RB of the remote terminal device, the remote terminal device may determine the identifier of the PC5 relay RLC channel corresponding to the RB based on the PC5SRAP configuration included in the first context, and then determine the first configuration information of the PC5 relay RLC channel corresponding to the identifier of the PC5 relay RLC channel. Optionally, the remote terminal device may receive the first packet of data in an RRC non-connected state based on the restored first context, including: the remote terminal device receives the first packet of data on the PC5 relay RLC channel using the first configuration information in the first context or the first configuration information sent by the relay terminal device. The remote terminal device may also determine the RB corresponding to the PC5 relay RLC channel based on the PC5SRAP configuration included in the first context.

[0191] Optionally, corresponding to method 1 of S420, for uplink transmission, the remote terminal device sends the first packet data to the relay terminal device in the RRC non-connected state based on the restored first context, including: after the remote terminal device receives the third indication information, it can send the first packet data of the remote terminal device to the relay terminal device in the RRC non-connected state based on the restored first context. The relay terminal device sends the first packet data to the network device, including: the relay terminal device can send the first packet data to the network device in the RRC connected state or the RRC non-connected state. Optionally, the relay terminal device sends the first packet data to the network device in the RRC non-connected state, including: the relay terminal device sends the first packet data to the network device using CG-SDT resources or RA-SDT resources in the RRC non-connected state according to the second context saved for transmitting the packet data of the remote terminal device. The second context stored by the relay terminal device may include first configuration information of the PC5 relay RLC channel corresponding to the identifier of the PC5 relay RLC channel, second configuration information of the Uu relay RLC channel corresponding to the identifier of the Uu relay RLC channel, and at least one of a PC5SRAP configuration or a UuSRAP configuration. Optionally, in the method of S420, the remote terminal device may transmit the first packet data with the relay terminal device in the RRC non-connected state based on the restored first context after the remote terminal device sends a first RRC request message to the relay terminal device.

[0192] Optionally, corresponding to the second mode of S420, for uplink transmission, the remote terminal device sends the first packet data to the relay terminal device in the RRC non-connected state based on the restored first context, including: the remote terminal device sends the first packet data to the relay terminal device based on the restored context, and after the relay terminal device receives the first packet data and the second indication information of the second mode of S420, it can determine that the remote terminal device has a need to transmit packet data according to the second indication information, and the relay terminal device may not discard the first packet data according to the second indication information, so that the loss of packet data can be avoided. For example, even if the relay terminal device is in the RRC non-connected state when receiving the first packet data, the first packet data may not be discarded. The relay terminal device sends the first packet data to the network device, including: the relay terminal device may enter the RRC connected state or send the first packet data to the network device in the RRC non-connected state. Optionally, if the remote terminal device sends a first packet data, an RRC request message and a second indication message to the relay terminal device, the remote terminal device may send the first packet data, the RRC request message and the second indication message to the relay terminal device at the same time, or may send the first packet data, the RRC request message and the second indication message to the relay terminal device separately. This embodiment of the present application does not limit this.

[0193] Optionally, the network device may send first timer information, the first timer information being used to indicate a first duration of a first timer for a remote terminal device to transmit packet data between the remote terminal device and the network device. The remote terminal device transmits the first packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state based on the restored first context, including: the remote terminal device transmits the first packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state based on the restored first context within the first duration. Optionally, the remote terminal device may start the first timer when initiating an RRC connection recovery process for packet data transmission or when sending a first RRC request message to the relay terminal device. The remote terminal device may stop the first timer when receiving an RRC response message to the RRC request message sent by the network device, or the remote terminal device may stop the first timer when packet transmission fails. After the first duration or the first timer expires, the remote terminal device deems that the transmission process of the remote terminal device's packet data through the relay terminal device is completed. Optionally, the remote terminal device may also enter an RRC idle state. It can be understood that the first timer is a timer dedicated to the remote terminal device performing packet data transmission between the remote terminal device and the network device.

[0194] Optionally, the network device may send a second timer information, and the second timer information is used to indicate the second duration of the second timer for the relay terminal device to transmit the packet data between the remote terminal device and the network device. Then, the relay terminal device and the network device transmit the first packet data, including: the relay terminal device transmits the first packet data between the remote terminal device and the network device within the second duration. Optionally, the relay terminal device may start the second timer when initiating the RRC connection recovery process for packet data transmission or when sending the second RRC request message of the relay terminal device to the network device. When the relay terminal device receives the RRC response message of the second RRC request message sent by the network device, it may stop the second timer, or the relay terminal device may stop the second timer when the packet transmission fails. After the second duration ends or the second timer times out, the relay terminal device considers that the transmission process of the packet data of the remote terminal device is completed. Optionally, the relay terminal device may also enter the RRC idle state. It can be understood that the second timer is a timer dedicated to the relay terminal device to perform packet data transmission between the remote terminal device and the network device. Optionally, when the first timer information exists, the second duration is less than the first duration. Because the remote terminal device initiates the RRC recovery process first and the relay terminal device initiates the RRC recovery process later, that is, the remote terminal device starts the first timer first and the relay terminal device starts the second timer later, if the second duration is less than the first duration, it can avoid the remote terminal device's first timer timing out and determining that the transmission has failed while the relay terminal device is performing transmission.

[0195] In the above scheme, the remote terminal device can transmit the first packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state, thereby avoiding the power consumption problem caused by the remote terminal device needing to enter the RRC connected state.

[0196] The method 400 is described below in conjunction with the communication method 500, but the communication method 500 should not limit the communication method 400. The communication method 500 corresponds to the communication method 400. As shown in FIG5 , the communication method 500 includes some or all of the following steps:

[0197] S501, the network device sends a first RRC response message to the remote terminal device through the relay terminal device, and the remote terminal device receives the first RRC response message through the relay terminal device. The first RRC response message is used to release the RRC connection between the remote terminal device and the network device.

[0198] For example, the first RRC response message is an RRC release message.

[0199] Optionally, the RRC release message may include indication information 1 and / or a suspension indication.

[0200] After S501 , the remote terminal device enters an RRC unconnected state, for example, an RRC inactive state.

[0201] Optionally, before S501, the remote terminal device may be in an RRC connected state, an RRC idle state, or an RRC inactive state. If before S501, the remote terminal device is in an RRC connected state, then before S501, the network device may send an RRC release message carrying a pause indication to release the remote terminal device to an RRC inactive state. If before S501, the remote terminal device is in an RRC inactive state, for example, before S501, the remote terminal device performs an SDT process, after the SDT process ends, the network device may send an RRC release message carrying a pause indication to allow the remote terminal device to continue to remain in the RRC inactive state. If before S501, the remote terminal device is in an RRC idle state, before S501, the remote terminal device may send an RRC setup request message to request to enter the RRC connected state, and the network device may send an RRC release message carrying a pause indication to release the remote terminal device to an RRC inactive state. That is, before S501, the remote terminal device can be in any RRC state, and the network device can determine to release the remote terminal device to the RRC inactive state. Among them, the network device sending the RRC release message to the remote terminal device can be understood as the network device sending the RRC release message to the remote terminal device through the relay terminal device.

[0202] For the description of indication information 1 and / or pause indication, please refer to the description of communication method 400 .

[0203] In some cases, method 500 further includes: the network device sends an RRC release message to the relay terminal device, the relay terminal device receives the RRC release message, and the relay terminal device may enter an RRC non-connected state. Optionally, the RRC release message may include indication information 2 and / or a pause indication. The relay terminal device may save a second context for transmitting packet data of the remote terminal device based on indication information 2 and / or the pause indication. The second context includes first configuration information corresponding to the PC5 relay RLC channel, second configuration information corresponding to the Uu relay RLC channel, at least one of a PC5 SRAP configuration or a Uu SRAP configuration. Optionally, the relay terminal device may forward the first packet data to the remote terminal device based on the saved second context in the RRC non-connected state. Of course, the relay terminal device may also forward the first packet data to the remote terminal device in the RRC connected state. In this case, the relay terminal device may not save the second context.

[0204] It is understandable that the remote terminal device storing the second context is an optional step, and the remote terminal device may not store the second context. In other words, the RRC release message may not include the indication information 2, and may not include the suspension indication.

[0205] S502: The remote terminal device saves a first context for transmitting packet data between the remote terminal device and the network device through the relay terminal device.

[0206] For S502 , please refer to the description of S410 .

[0207] S503, the network device broadcasts the first indication information, the relay terminal device and / or the remote terminal device can receive the first indication information, and the first indication information can indicate that the network device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state.

[0208] Optionally, in S503, the network device may further broadcast at least one of first RSRP threshold value information, first data volume threshold value information, first timer information, or second timer information. Specifically, the first RSRP threshold value information, the first data volume threshold value information, the first timer information, and the second timer information can be found in the description of method 400.

[0209] Optionally, in S503, the network device may broadcast at least one of the first indication information, the first RSRP threshold value information or the first data volume threshold value information, the first timer information or the second timer information in the system information block (SIB) 1.

[0210] S504: If the transmission conditions of the small packet data are met, the remote terminal device restores the first context.

[0211] Specifically, for S504 , please refer to the description of S420 .

[0212] S505, if the transmission conditions of the packet data are met, the remote terminal device can send a first RRC request message to the relay terminal device, and the relay terminal device receives the first RRC request message from the remote terminal device, where the first RRC request message includes second indication information.

[0213] Here, S505 refers to the first method of the communication method 400 .

[0214] Optionally, if there is a connection between the remote terminal device and the relay terminal device, for example, there is a PC5-S connection or a PC5-RRC connection, the remote terminal device may send a first RRC request message to the relay terminal device through the PC5-S connection or the PC5-RRC connection. If there is no connection between the remote terminal device and the relay terminal device, the remote terminal device may discover a relay terminal device, and after establishing a connection with the relay terminal device, send a first RRC request message to the relay terminal device. Optionally, the remote terminal device may use a default configuration (for example, the default SL-RLC0 configuration) to send the first RRC request message to the relay terminal device, and the relay terminal device may also use the default configuration (for example, the default SL-RLC0 configuration) to receive the first RRC request message sent by the remote terminal device. Optionally, the remote terminal device may restore the PDCP context and use the default configuration to send the first RRC request message to the relay terminal device.

[0215] Optionally, the first RRC request message may be an RRC resume request (RRCresumeRequest) message.

[0216] If the relay terminal device is in the RRC non-connected state, S506 can be executed.

[0217] S506: The relay terminal device sends a second RRC request message of the relay terminal device to the network device, and the network device receives the second RRC request message of the relay terminal device from the relay terminal device.

[0218] Optionally, S505 may trigger S506. For example, when the relay terminal device receives a first RRC request message sent by the remote terminal device, the relay terminal device may initiate an RRC connection recovery or establishment process and transmit a second RRC request message through the RRC connection recovery or establishment process. Optionally, the RRC connection recovery process may be used by the relay terminal device to perform an SDT process or to request that the relay terminal device enter an RRC connected state.

[0219] S507: The network device sends a second RRC response message of the relay terminal device to the relay terminal device, and the relay terminal device receives the second RRC response message of the relay terminal device from the network device.

[0220] The second RRC response message may be a response message to the second RRC request message.

[0221] After executing S506 and S507, an RRC connection is established between the relay terminal device and the network device. If an RRC connection already exists between the relay terminal device and the network device, S506 and S507 may not exist.

[0222] For example, if before S506, the relay terminal device is in the RRC inactive state, the second RRC request message in S506 may be an RRC recovery request message, and the second RRC response message in S507 may be an RRC recovery message; for another example, if before S506, the relay terminal device is in the RRC idle state, the second RRC request message in S506 may be an RRC establishment request message, and the second RRC response message in S507 may be an RRC establishment message.

[0223] S508: The relay terminal device sends identification information of the remote terminal device to the network device, and the network device may receive the identification information of the remote terminal device from the relay terminal device.

[0224] Optionally, the identification information of the remote terminal device may be included in the sidelink UE information message.

[0225] Optionally, the identification information of the remote terminal device is used to indicate the remote terminal device. For example, the identification information of the remote terminal device may be a layer 2 identifier of the remote terminal device, which may be 24 bits, or may be an index of the remote terminal device at the relay terminal device, etc.

[0226] S509: The network device sends third configuration information to the relay terminal device, and the relay terminal device receives the third configuration information from the network device.

[0227] Optionally, in S509, the network device may send third configuration information to the relay terminal device based on the identification information of the remote terminal device. That is, the network device may determine the remote terminal device based on the identification information and send third configuration information related to the remote terminal device to the relay terminal device.

[0228] Optionally, the third configuration information is used by the relay terminal device to transmit the first RRC request message of the remote terminal device. Optionally, the third configuration information may further include configuration information related to the remote terminal device corresponding to the identification information sent by the relay terminal device in S508. For example, it may include information for the relay terminal device to transmit packet data of the remote terminal device, such as at least one of the first configuration information of the PC5 relay RLC channel, the PC5 SRAP configuration, the second configuration information of the Uu relay RLC channel, or the Uu SRAP configuration.

[0229] S510, the relay terminal device sends the first RRC request message in S505 to the network device according to the third configuration information, and the network device receives the first RRC request message from the relay terminal device, where the first RRC request message includes second indication information.

[0230] Optionally, the network device may determine that the remote terminal device has a transmission requirement for small packet data based on the second indication information in the first RRC request message. Optionally, the first RRC request message may include terminal identification information, where the terminal identification information is used to identify the remote terminal device. The network device may determine which remote terminal device has a transmission requirement for small packet data based on the terminal identification information in the first RRC request message.

[0231] Optionally, if at S505 , the relay terminal device is in an RRC connected state and the relay terminal device already has the third configuration information, the relay terminal device may directly execute S510 .

[0232] S511: The network device sends third indication information to the remote terminal device through the relay terminal device.

[0233] Optionally, the third indication information may be included in a third RRC response message, wherein the third RRC response message may be a response message to the first RRC request message, and the third RRC response message will not switch the remote terminal device to the RRC connected state.

[0234] For the description of the third indication information, please refer to the description in the first mode of method 400 .

[0235] S512: The relay terminal device forwards the third indication information of the remote terminal device to the remote terminal device, and the remote terminal device receives the third indication information of the remote terminal device from the relay terminal device.

[0236] For the description of the third indication information, please refer to the description in the first mode of method 400 .

[0237] It is understandable that, through S511 and S512, the network device can send the third indication information to the remote terminal device, so that the remote terminal device knows that the network device has successfully received the first RRC request message. The network device first sends the third indication information to the relay terminal device in S511, and the relay terminal device then forwards the third indication information to the remote terminal device in S512.

[0238] In some embodiments, S512 may be replaced by the relay terminal device sending fourth indication information to the remote terminal device. In this case, S511 may not be present. That is, the relay terminal device notifies the remote terminal device via the fourth indication information that the network device has successfully received the first RRC request message. For a description of the fourth indication information, refer to the description of Method 1 of Method 400.

[0239] For uplink transmission, S513a and S514a may exist:

[0240] The remote terminal device may execute S513a and S514a after receiving the third indication information. It is understandable that, after receiving the third indication information, the remote terminal device may learn that the network device has successfully received the first RRC request message, or that the initial transmission of the remote terminal device's packet data has been successful, or that the network device has learned that the remote terminal device has a packet data transmission requirement, or that the network device has confirmed the first RRC request message, or that the network device has triggered the remote terminal device to send the first packet data. The remote terminal device may then transmit the first packet data after receiving the third indication information, thereby avoiding data loss or data transmission failure caused by the remote terminal device sending the first packet data when the network device fails to successfully parse the first RRC request message or the initial transmission of the remote terminal device's packet data fails.

[0241] Alternatively, the remote terminal device may execute S513a and S514a after receiving the fourth indication information. It is understandable that, after receiving the fourth indication information, the remote terminal device may learn that the network device has successfully received the first RRC request message, or that the initial transmission of the remote terminal device's packet data has been successful, or that the network device has learned that the remote terminal device has a packet data transmission requirement, or that the network device has confirmed the first RRC request message, or that the network device has triggered the remote terminal device to send the first packet data. The remote terminal device may then transmit the first packet data after receiving the fourth indication information, thereby avoiding data loss or data transmission failure caused by the remote terminal device sending the first packet data when the network device fails to successfully parse the first RRC request message or the initial transmission of the remote terminal device's packet data fails.

[0242] S513a: The remote terminal device sends a first packet of data to the relay terminal device according to the stored first context, and the relay terminal device receives the first packet of data from the remote terminal device.

[0243] Optionally, at S513a, if the relay terminal device is in an RRC connected state, then after S510 and before S513a, the network device may configure the relay terminal device with fourth configuration information for the relay terminal device to transmit packet data of the remote terminal device. For example, the fourth configuration information may include the first configuration information and / or PC5SRAP configuration of the PC5 relay RLC channel. At this time, S513a includes: the remote terminal device sends the first packet data to the relay terminal device according to the first configuration information and / or PC5SRAP configuration in the saved first context, and the relay terminal device receives the first packet data from the remote terminal device according to the first configuration information and / or PC5SRAP configuration in the fourth configuration information. Optionally, the first configuration information included in the fourth configuration information should be the same as the first configuration information in the first context. Optionally, the PC5SRAP configuration included in the fourth configuration information should be the same as the PC5SRAP configuration in the first context.

[0244] Optionally, if the third configuration information includes the first configuration information and / or PC5SRAP configuration of the PC5 relay RLC channel, then S513a includes: the remote terminal device sending the first packet data to the relay terminal device according to the first configuration information and / or PC5SRAP configuration stored in the first context; the relay terminal device receiving the first packet data from the remote terminal device according to the first configuration information and / or PC5SRAP configuration in the third configuration information; and the remote terminal device receiving the first packet data from the relay terminal device according to the first configuration information and / or PC5SRAP configuration stored in the first context. The fourth configuration information may not be present at this time. Optionally, the first configuration information included in the third configuration information should be the same as the first configuration information in the first context. Optionally, the PC5SRAP configuration included in the third configuration information should be the same as the PC5SRAP configuration in the first context.

[0245] S514a, the relay terminal device sends a first packet of data to the network device, and the network device receives the first packet of data from the relay terminal device.

[0246] Optionally, at S514a, the relay terminal device is in an RRC connected state. Then, after S510 and before S514a, the network device may configure the relay terminal device with fifth configuration information for transmitting the remote terminal device to the relay terminal device. For example, the fifth configuration information may include the second configuration information of the Uu relay RLC channel and / or the Uu SRAP configuration. At this time, S514a includes: the relay terminal device sends the first packet data to the network device according to the second configuration information and / or the Uu SRAP configuration of the Uu relay RLC channel in the fifth configuration information, and the network device may receive the first packet data from the relay terminal device according to the second configuration information and / or the Uu SRAP configuration of the Uu relay RLC channel.

[0247] For downlink transmission, S513b and S514b may exist:

[0248] S513b, the network device sends the first packet data to the relay terminal device, and the relay terminal device receives the first packet data from the network device.

[0249] Optionally, at S513b, the relay terminal device is in an RRC connected state. Then, after S510 and before S513b, the network device may configure the relay terminal device with fifth configuration information for the relay terminal device to transmit packet data of the remote terminal device. For example, the fifth configuration information may include the second configuration information of the Uu relay RLC channel and / or the Uu SRAP configuration. At this time, S513b includes: the network device may send the first packet data to the relay terminal device according to the second configuration information of the Uu relay RLC channel and / or the Uu SRAP configuration, and the relay terminal device receives the first packet data from the network device according to the second configuration information of the Uu relay RLC channel and / or the Uu SRAP configuration in the fifth configuration information.

[0250] S514b: The relay terminal device sends a first packet of data to the remote terminal device, and the remote terminal device receives the first packet of data from the relay terminal device according to the stored first context.

[0251] Optionally, at S514b, the relay terminal device is in an RRC connected state. Then, after S510 and before S514b, the network device may configure the relay terminal device with fourth configuration information for the relay terminal device to transmit the remote terminal device. For example, the fourth configuration information may include the first configuration information and / or PC5SRAP configuration of the PC5 relay RLC channel. At this time, S514b includes: the relay terminal device sends the first packet data to the remote terminal device according to the first configuration information and / or PC5SRAP configuration in the fourth configuration information, and the remote terminal device receives the first packet data from the relay terminal device according to the first configuration information and / or PC5SRAP configuration in the saved first context. Optionally, the first configuration information included in the fourth configuration information should be the same as the first configuration information in the first context. Optionally, the PC5SRAP configuration included in the fourth configuration information should be the same as the PC5SRAP configuration in the first context.

[0252] Optionally, if the third configuration information includes first configuration information and / or PC5SRAP configuration for the PC5 relay RLC channel, then S514b includes: the relay terminal device sending the first packet data to the remote terminal device according to the first configuration information and / or PC5SRAP configuration in the third configuration information, and the remote terminal device receiving the first packet data from the relay terminal device according to the first configuration information and / or PC5SRAP configuration stored in the first context. The fourth configuration information may not be present at this time. Optionally, the first configuration information included in the third configuration information should be the same as the first configuration information in the first context. Optionally, the PC5SRAP configuration included in the third configuration information should be the same as the PC5SRAP configuration in the first context.

[0253] Optionally, the above description is about the case where the relay terminal device enters the RRC connection state and sends the first RRC request message to the network device in S510. In some cases, the relay terminal device may not enter the RRC connection state to send the first RRC request message to the network device. For example, the relay terminal device may send the second RRC request message of the relay terminal device and / or the first RRC request message of the remote terminal device to the network device in S506 through CG-SDT resources, RA-SDT resources, or RA resources in the RRC non-connected state. Optionally, the relay terminal device may save a second context when it is in the RRC non-connected state. For uplink transmission, at this time, S513a includes: the remote terminal device sends the first packet data to the relay terminal device according to the first configuration information and / or PC5SRAP configuration in the saved first context, and the relay terminal device receives the first packet data from the remote terminal device according to the first configuration information and / or PC5SRAP configuration in the saved second context. S514a includes: the relay terminal device sends the first packet data to the network device according to the second configuration information and / or Uu SRAP configuration of the Uu relay RLC channel in the second context, and the network device receives the first packet data from the relay terminal device according to the second configuration information and / or Uu SRAP configuration of the Uu relay RLC channel. For downlink transmission, S513b includes: the network device sends the first packet data to the relay terminal device according to the second configuration information and / or Uu SRAP configuration of the Uu relay RLC channel in the second context, and the relay terminal device receives the first packet data from the network device according to the second configuration information and / or Uu SRAP configuration of the Uu relay RLC channel in the second context. S514b also includes: the relay terminal device sends the first packet data to the remote terminal device according to the first configuration information and / or PC5SRAP configuration stored in the second context, and the remote terminal device receives the first packet data from the relay terminal device according to the first configuration information and / or PC5SRAP configuration stored in the first context.

[0254] After S514a or S514b, the communication method 500 may further include:

[0255] S515: The network device sends an RRC release message to the remote terminal device through the relay terminal device.

[0256] Optionally, the RRC release message in S515 may release the remote terminal device, and the remote terminal device enters an RRC inactive state.

[0257] In the above-mentioned communication method 500, the network device can send a first RRC response message to the remote terminal device, and the first RRC response message can release the remote terminal device to the RRC inactive state. The remote terminal device can save the first context according to the indication information 1 and / or the suspension indication in the first RRC response message. When the remote terminal device has a transmission requirement for small packet data, it can determine whether the transmission conditions are met. If the transmission conditions are met, it can send a first RRC request message to the relay terminal device. The first RRC request message includes second indication information, and the relay terminal device may not perceive the first RRC request message. The relay terminal device can transmit the first small packet data of the remote terminal device to the network device in the RRC connected state or the RRC non-connected state, avoiding the need for the remote terminal device to enter the RRC connected state to send the first small packet data of the remote terminal device to the network device, thereby reducing the power consumption of the remote terminal device when entering the RRC connected state.

[0258] Method 400 is described below in conjunction with communication method 600, but communication method 600 should not limit communication method 400. Communication method 600 corresponds to mode 2 of communication method 400. As shown in FIG6 , communication method 600 includes some or all of the following steps:

[0259] S601-S604 are the same as S501-S504 respectively.

[0260] S605, the remote terminal device sends second indication information and a first RRC request message to the relay terminal device, and the relay terminal device receives the second indication information and the first RRC request message from the remote terminal device, where the second indication information is used to indicate that the remote terminal device has a transmission requirement for small packet data.

[0261] For the description of the second indication information and the first RRC request message, please refer to the description of mode 2 in the communication method 400.

[0262] Optionally, in S605, the remote terminal device may send the second indication information and the first RRC request message to the relay terminal device simultaneously, or may send the second indication information and the first RRC request message separately, and this embodiment of the present application does not limit this. If the remote terminal device sends the second indication information and the first RRC request message simultaneously, the remote terminal device may package the third MAC CE including the second indication information and the first RRC request message together and send them to the relay terminal device. For example, the remote terminal device packages the third MAC CE including the second indication information and the first RRC request message into a first MAC PDU, and sends the first MAC PDU to the relay terminal device. Alternatively, if the remote terminal device sends the second indication information and the first RRC request message at the same time, the remote terminal device may package the third MAC subheader including the second indication information and the first RRC request message together and send the package to the relay terminal device. For example, the remote terminal device packages the third MAC subheader including the second indication information and the RRC request message into a first MAC PDU, and sends the first MAC PDU to the relay terminal device. The third MAC subheader may be a MAC subheader used to identify the first RRC request message. Alternatively, if the remote terminal device sends the second indication information and the first RRC request message at the same time, the remote terminal device may package the SRAP information including the second indication information and the first RRC request message together and send the package to the relay terminal device. For example, the remote terminal device packages the SRAP information including the second indication information and the RRC request message into a first MAC PDU, and sends the first MAC PDU to the relay terminal device.

[0263] Optionally, if there is a connection between the remote terminal device and the relay terminal device, for example, there is a PC5-S connection or a PC5-RRC connection, the remote terminal device may send a second indication message and a first RRC request message to the relay terminal device through the PC5-S connection or the PC5-RRC connection. If there is no connection between the remote terminal device and the relay terminal device, the remote terminal device may discover a relay terminal device, and after establishing a connection with the relay terminal device, send a second indication message and a first RRC request message to the relay terminal device. Optionally, the remote terminal device may use a default configuration (for example, the default SL-RLC0 configuration) to send the first RRC request message to the relay terminal device, and the relay terminal device may also use the default configuration (for example, the default SL-RLC0 configuration) to receive the first RRC request message sent by the remote terminal device. Optionally, the remote terminal device may restore the PDCP context and use the default configuration to send the first RRC request message to the relay terminal device.

[0264] Optionally, the first RRC request message may be an RRC resume request (RRCresumeRequest) message.

[0265] Optionally, in some cases, the remote terminal device may also send the first packet data to the relay terminal device. For example, in S605, the remote terminal device may send one or more of the second indication information, the first RRC request message, or the first packet data to the relay terminal device. Optionally, if the remote terminal device sends the first packet data to the relay terminal device, the remote terminal device may send the first packet data to the relay terminal device based on the first configuration information and / or the PC5SRAP configuration stored in the first context. It is understandable that since the relay terminal device receives the second indication information, the relay terminal device can be aware of the packet data demand of the remote terminal device. Therefore, after receiving the first packet data, the relay terminal device will not discard the first packet data. Therefore, the remote terminal device can send the first packet data in S605.

[0266] In one implementation, if the relay terminal device is in an RRC non-connected state in S605, the relay terminal device may enter an RRC connected state to transmit the first packet data, and the relay terminal device may execute S606a to S610a.

[0267] S606a, the relay terminal device sends a second RRC request message of the relay terminal device to the network device, and the network device receives the second RRC request message of the relay terminal device from the relay terminal device.

[0268] Optionally, S605 can trigger S606a. For example, the relay terminal device receives the first RRC request message sent by the remote terminal device, and the relay terminal device initiates an RRC connection recovery or establishment process, and transmits a second RRC request message through the RRC connection recovery or establishment process. Optionally, the RRC connection recovery process can be used for the relay terminal device to request to enter the RRC connection state. Optionally, in S606a, the relay terminal device can send fifth indication information and the second RRC request message of the relay terminal device to the network device based on the second indication information, and the network device can receive the fifth indication information and the second RRC request message from the relay terminal device, wherein the fifth indication information is used to indicate the transmission requirement with small packet data, and the network device can determine the transmission requirement with small packet data based on the fifth indication information. For example, the fifth indication information is cause value information, wherein, for the description of the fifth indication information, please refer to the description of method two in communication method 400.

[0269] S607a: The network device sends a second RRC response message of the relay terminal device to the relay terminal device, and the relay terminal device receives the second RRC response message of the relay terminal device from the network device.

[0270] The second RRC response message may be a response message to the second RRC request message.

[0271] After executing S606a and S607a, an RRC connection is established between the relay terminal device and the network device. If an RRC connection already exists between the relay terminal device and the network device, S606a and S607a may not exist.

[0272] For example, if before S606a, the relay terminal device is in the RRC inactive state, the second RRC request message in S606a may be an RRC recovery request message, and the second RRC response message in S607a may be an RRC recovery message; for another example, if before S606a, the relay terminal device is in the RRC idle state, the second RRC request message in S606a may be an RRC establishment request message, and the second RRC response message in S607a may be an RRC establishment message.

[0273] S608a: The relay terminal device sends identification information of the remote terminal device to the network device, and the network device may receive the identification information of the remote terminal device from the relay terminal device.

[0274] Optionally, the identification information of the remote terminal device may be included in the sidelink UE information message.

[0275] Optionally, the identification information of the remote terminal device is used to indicate the remote terminal device. For example, the identification information of the remote terminal device may be a layer 2 identifier of the remote terminal device, which may be 24 bits, or may be an index of the remote terminal device at the relay terminal device.

[0276] Optionally, in S608a, the relay terminal device may send fifth indication information and identification information of the remote terminal device to the network device based on the second indication information. For example, the sidelink UE information message includes the fifth indication information and identification information of the remote terminal device. The network device may receive the fifth indication information and identification information of the remote terminal device from the relay terminal device. For example, the fifth indication information is used to indicate a transmission requirement for small packet data. The network device may determine that the remote terminal device identified by the identification information has a transmission requirement for small packet data based on the fifth indication information. For a description of the fifth indication information, refer to the description of method 2 in communication method 400. Optionally, the relay terminal device may send the fifth indication information to the network device in S608a, or may send the fifth indication information to the network device in other steps after S608a.

[0277] S609a: The network device sends third configuration information to the relay terminal device, and the relay terminal device receives the third configuration information from the network device.

[0278] For the content of S609a, please refer to S509.

[0279] S610a: The relay terminal device sends the first RRC request message in S605 to the network device, and the network device receives the first RRC request message from the relay terminal device. Alternatively, the relay terminal device sends fifth indication information and the first RRC request message in S605 to the network device, and the network device receives the first RRC request message and the fifth indication information from the relay terminal device.

[0280] Optionally, if the third configuration information is used for the relay terminal device to transmit the first RRC request message of the remote terminal device, then in S610a, the relay terminal device can send the first RRC request message in S605 to the network device according to the third configuration information, and the network device receives the first RRC request message from the relay terminal device.

[0281] Optionally, if at S605 , the relay terminal device is in an RRC connected state and the relay terminal device already has the third configuration information, the relay terminal device may directly execute S610a .

[0282] Optionally, if the fifth indication information is not sent in S606a and S608a, the relay terminal device may send the first RRC request message and the fifth indication information to the network device in S610a, and the network device receives the first RRC request message and the fifth indication information from the relay terminal device. For a description of the fifth indication information, refer to the description of method 2 in communication method 400.

[0283] In another implementation, if the relay terminal device is in the RRC non-connected state in S605, the relay terminal device may continue to transmit the first packet data in the RRC non-connected state, and the relay terminal device may execute S606b.

[0284] S606b: The relay terminal device sends one or more of the following: a first RRC request message of the remote terminal device, a second RRC request message of the relay terminal device, identification information of the remote terminal device, fifth indication information, or first packet data to the network device. The network device receives one or more of the following: the first RRC request message of the remote terminal device, the second RRC request message of the relay terminal device, identification information of the remote terminal device, fifth indication information, or first packet data from the relay terminal device.

[0285] Optionally, S605 may trigger S606b. For example, when the relay terminal device receives a first RRC request message sent by the remote terminal device, the relay terminal device may initiate an RRC connection recovery process and transmit a second RRC request message through the RRC connection recovery process. Optionally, the RRC connection recovery process may be used by the relay terminal device to perform SDT.

[0286] Optionally, when the relay terminal device remains in the RRC inactive state and sends one or more of the first RRC request message of the remote terminal device, the second RRC request message of the relay terminal device, the identification information of the remote terminal device, the fifth indication information or the first packet data to the network device, the relay terminal device may use CG-SDT resources or RA-SDT resources. RA-SDT can be understood as small data transmission (SDT) through random access (RA), such as sending through msg3 or msgA of RA-SDT. CG-SDT can be understood as SDT through pre-configured resources (configured grant, CG), such as sending using CG-SDT resources.

[0287] For example, the identification information and / or the fifth indication information of the remote terminal device can be both included in the sidelink UE information message. In this case, if resources are sufficient, the relay terminal device can send the first RRC request message, the second RRC request message, the first packet data and the sidelink UE information message to the network device. For another example, the fifth indication information can be in the second RRC request message. In this case, if resources are sufficient, the relay terminal device can send the first RRC request message, the second RRC request message and the first packet data to the network device.

[0288] If the relay terminal device is unable to send the first RRC request message, the second RRC request message, the fifth indication information, and the first packet data to the network device in S606b, the relay terminal device may send a portion of the information along with a buffer status report in S606b. The network device may schedule resources for the relay terminal device based on the buffer status report, and the relay terminal device may use the resources scheduled by the base station to send the remaining information. Alternatively, when the relay terminal device uses CG-SDT resources, the relay terminal device may use the CG-SDT resources at time 1 to send a portion of the information, and then use the CG-SDT resources at time 2 to send the remaining information.

[0289] Optionally, the relay terminal device may use the saved second context to send the first packet data to the network device. For example, the relay terminal device sends the first packet data to the network device based on the second configuration information and / or the Uu SRAP configuration of the Uu relay RLC channel in the second context, and the network device may receive the first packet data from the relay terminal device based on the second configuration information and / or the Uu SRAP configuration of the Uu relay RLC channel.

[0290] Optionally, the relay terminal device may use the saved second context to send a first RRC request message to the network device. For example, the relay terminal device sends the first RRC request message to the network device based on the second configuration information and / or Uu SRAP configuration of the Uu relay RLC channel in the second context, and the network device may receive the first RRC request message from the relay terminal device based on the second configuration information and / or Uu SRAP configuration of the Uu relay RLC channel.

[0291] Optionally, if in S605, the remote terminal device sends the first small packet of data to the relay terminal device, S606b may send the first small packet of data.

[0292] S611-S612 are the same as S511-S512 respectively.

[0293] In one implementation, if the relay terminal device enters the RRC connected state to transmit packet data, the relay terminal device may transmit the first packet data to the network device in the RRC connected state, and the subsequent steps are the same as S513a and S514a. Alternatively, the relay terminal device may receive the first packet data transmission sent by the network device in the RRC connected state and forward it to the remote terminal device, and the subsequent steps are the same as S513b and S514b.

[0294] In another implementation, if the relay terminal device maintains transmitting packet data in the RRC non-connected state, the relay terminal device may transmit the second packet data to the network device in the RRC non-connected state, in which case steps S613a and S614a are executed. Alternatively, the relay terminal device may receive the first packet data transmission sent by the network device in the RRC non-connected state and forward it to the remote terminal device, in which case steps S613b and S614b are executed.

[0295] S613a, the remote terminal device sends the second packet data to the relay terminal device according to the stored first context, and the relay terminal device receives the second packet data from the remote terminal device.

[0296] Optionally, the relay terminal device may save a second context when it is in an RRC non-connected state. For uplink transmission, S613a at this time includes: the remote terminal device sends a second packet data to the relay terminal device according to the first configuration information and / or PC5SRAP configuration in the saved first context, and the relay terminal device receives the second packet data from the remote terminal device according to the first configuration information and / or PC5SRAP configuration in the saved second context.

[0297] Optionally, if in S605, the remote terminal device sends the first packet data to the relay terminal device, the second packet data in S613a can be the packet data after the first packet data; if in S605, the remote terminal device does not send the first packet data to the relay terminal device, the second packet data in S613a can be the first packet data.

[0298] S614a, the relay terminal device sends the second packet data to the network device, and the network device receives the second packet data from the relay terminal device.

[0299] Optionally, the relay terminal device may store a second context when it is in an RRC non-connected state. For uplink transmission, S614a includes: the relay terminal device sends second packet data to the network device according to the second configuration information and / or Uu SRAP configuration of the Uu relay RLC channel in the second context, and the network device may receive the second packet data from the relay terminal device according to the second configuration information and / or Uu SRAP configuration of the Uu relay RLC channel. The remote terminal device may execute S613a and S614a after receiving the third indication information. It can be understood that after receiving the third indication information, the remote terminal device may know that the network device has successfully received the first RRC request message, or the initial transmission of the packet data of the remote terminal device is successful, or the network device has known that the remote terminal device has a packet data transmission requirement, or the network device confirms the first RRC request message, or the network device triggers the remote terminal device to send the second packet data. The remote terminal device can then transmit the second packet data after receiving the third indication information, avoiding data loss or data transmission failure caused by the remote terminal device continuing to send the second packet data when the network device fails to successfully parse the first RRC request message or the initial transmission of the remote terminal device's packet data fails.

[0300] Alternatively, the remote terminal device may execute S613a and S614a after receiving the fourth indication information. It is understandable that, after receiving the fourth indication information, the remote terminal device may learn that the network device has successfully received the first RRC request message, or that the initial transmission of the remote terminal device's packet data has been successful, or that the network device has learned that the remote terminal device has a packet data transmission requirement, or that the network device has confirmed the first RRC request message, or that the network device has triggered the remote terminal device to send a second packet data. The remote terminal device may then transmit the second packet data after receiving the fourth indication information, thereby avoiding data loss or data transmission failure caused by the remote terminal device continuing to send the second packet data when the network device fails to successfully parse the first RRC request message or the initial transmission of the remote terminal device's packet data fails.

[0301] S613b, the network device sends the first packet data to the relay terminal device, and the relay terminal device receives the first packet data from the network device.

[0302] Optionally, the relay terminal device can save a second context when it is in the RRC non-connected state. For downlink transmission, S613b at this time includes: the network device can send the first packet data to the relay terminal device according to the second configuration information of the Uu relay RLC channel and / or the Uu SRAP configuration, and the relay terminal device receives the first packet data from the network device according to the second configuration information of the Uu relay RLC channel and / or the Uu SRAP configuration in the second context.

[0303] S614b: The relay terminal device sends a first packet of data to the remote terminal device, and the remote terminal device receives the first packet of data from the relay terminal device according to the stored first context.

[0304] Optionally, the relay terminal device may save a second context when it is in an RRC non-connected state. For downlink transmission, S614b includes: the relay terminal device sends a first packet data to the remote terminal device according to the first configuration information and / or PC5SRAP configuration saved in the second context, and the remote terminal device receives the first packet data from the relay terminal device according to the first configuration information and / or PC5SRAP configuration saved in the first context.

[0305] After performing packet data transmission, the communication method 600 may further include:

[0306] S615: The network device sends an RRC release message to the remote terminal device through the relay terminal device.

[0307] Optionally, the RRC release message in S615 may release the remote terminal device, and the remote terminal device enters an RRC inactive state.

[0308] In the above-described method 600, the network device may send a first RRC response message to the remote terminal device. The first RRC response message may release the remote terminal device to an RRC inactive state. The remote terminal device may save the first context based on the indication information 1 and / or the suspension indication in the first RRC response message. When the remote terminal device has a need to transmit small packet data, it may determine whether the transmission conditions are met. If the transmission conditions are met, it may send a first RRC request message and second indication information to the relay terminal device. The relay terminal device may perceive the small packet data transmission need of the remote terminal device. In this way, even if the relay terminal device receives the first small packet data in S605, it will not be discarded. Furthermore, the relay terminal device sends fifth indication information to the network device based on the second indication information. The relay terminal device may transmit the first small packet data of the remote terminal device to the network device in an RRC connected state or an RRC non-connected state, thereby avoiding the need for the remote terminal device to enter the RRC connected state to transmit the first small packet data of the remote terminal device to the network device, thereby reducing the power consumption of the remote terminal device when entering the RRC connected state.

[0309] In the above-mentioned communication methods 400 to 600, the network device may be a network device accessed by a relay terminal device. If, as the relay terminal device moves, the relay terminal device moves from the coverage area of ​​the second network device to the coverage area of ​​the first network device, but the second network device saves the first context of the remote terminal device, the remote terminal device will be unable to send the first packet data to the first network device through the relay terminal device according to the first context. The following describes the situation in which the relay terminal device moves from the coverage area of ​​the second network device to the coverage area of ​​the first network device in conjunction with communication method 700. As shown in FIG7, communication method 700 includes some or all of the following steps:

[0310] S701: The second network device sends a first RRC response message to the remote terminal device through the relay terminal device, and the remote terminal device receives the first RRC response message through the relay terminal device.

[0311] Optionally, the first RRC response message may be an RRC release message. After receiving the RRC release message, the remote terminal device may enter an RRC inactive state.

[0312] Specifically, the description of S701 may refer to the description of S501 . That is, the network device in S501 may be the second network device in the communication method 700 .

[0313] S702, same as S502.

[0314] S703, the first network device broadcasts the first indication information, the relay terminal device and / or the remote terminal device can receive the first indication information, and the first indication information can indicate that the first network device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state.

[0315] Specifically, the description of S703 may refer to the description of S503 , that is, the network device in S503 may be the first network device in the communication method 700 .

[0316] S704, same as S504.

[0317] S705, the remote terminal device sends a first RRC request message and / or second indication information to the relay terminal device, and the relay terminal device receives and sends the first RRC request message and / or second indication information.

[0318] In one implementation, in S705 , the remote terminal device sends a first RRC request message to the relay terminal device, where the first RRC request message includes second indication information, which corresponds to method 500 .

[0319] In another implementation, in S705, the remote terminal device sends a first RRC request message and a second indication message to the relay terminal device, the first RRC request message and the second indication message are independent, and in S705, the remote terminal device can also send a first packet data to the relay terminal device, which corresponds to method 600.

[0320] S706, the relay terminal device sends one or more of the first RRC request message, the second RRC request message, the identification information of the remote terminal device, the fifth indication information or the first packet data to the first network device.

[0321] In one implementation, in S706, the relay terminal device sends a first RRC request message, a second RRC request message, and identification information of the remote terminal device to the first network device in the manner of method 500, and the first RRC request message includes the second indication information.

[0322] In another implementation, in S706, the relay terminal device sends the first RRC request message, the second RRC request message, the identification information of the remote terminal device, and the fifth indication information to the first network device in the manner of method 600.

[0323] Among them, in S706, the relay terminal device sends the first RRC request message, the second RRC request message, the identification information of the remote terminal device, the fifth indication information or at least two of the first packet data to the first network device at the same time, or may send the first RRC request message, the second RRC request message, the identification information of the remote terminal device, the fifth indication information or at least two of the first packet data separately. The embodiment of the present application does not impose any restrictions on the order of sending the first RRC request message, the second RRC request message, the identification information of the remote terminal device, the fifth indication information or the first packet data.

[0324] If, in S706, the relay terminal device sends a second RRC request message of the relay terminal device to the first network device, S707 may be executed.

[0325] S707, the first network device sends sixth indication information to the second network device, and the second network device receives the sixth indication information from the first network device, where the sixth indication information is used to request the relay terminal device to transmit the second context of the packet data of the remote terminal device.

[0326] Optionally, when the first network device receives the second RRC request message from the relay terminal device, execution of S707 is triggered. After the first network device receives the fifth indication information sent by the relay terminal device, it can be informed that there is a transmission demand for small packet data. Therefore, execution of S707 can be triggered.

[0327] Optionally, S707 includes: the first network device sending a first Xn interface request message to the second network device, where the first Xn interface request message may include sixth indication information. For example, the first Xn interface request message may be a RETRIEVE UE CONTEXT REQUEST message.

[0328] Optionally, in addition to being used to request the relay terminal device to transmit the second context of the packet data of the remote terminal device, the sixth indication information can also be used to request the relay terminal device to execute a relay-related context, wherein the execution of the relay-related context includes both the second context and the context of the relay terminal device transmitting the non-packet data of the remote terminal device.

[0329] S708: The second network device sends a second context to the first network device, and the first network device receives the second context from the second network device.

[0330] Optionally, S708 includes: the second network device may send a first Xn interface response message to the first network device, where the first Xn interface response message includes the second context. The first Xn interface response message may be a response message to the first Xn interface request message, for example, the first Xn interface response message may be a RETRIEVE UE CONTEXT RESPONSE message or a PARTIAL UE CONTEXT TRANSFER message.

[0331] S709, the first network device may send seventh indication information to the second network device, and the second network device may receive the seventh indication information from the first network device, where the seventh indication information is used to request a first context related to packet data of a remote terminal device.

[0332] Optionally, the first network device can parse the first RRC request message from the relay terminal device based on the second context, thereby triggering the execution of S709. Optionally, if the first RRC request message includes second indication information, the first network device can be informed based on the second indication information that the remote terminal device has a small packet data transmission requirement, and thus can execute S709. Since the first network device also receives the second RRC request message, the first network device can determine that the recovery process initiated by the current relay terminal device is for the small packet data transmission of the remote terminal device, and therefore the first network device sends the seventh indication information to the second network device to request the relevant context, thereby ensuring the small packet data transmission of the remote terminal device.

[0333] Optionally, S709 includes: the first network device sending a second Xn interface request message to the second network device, where the first Xn interface request message may include seventh indication information. For example, the second Xn interface request message may be a RETRIEVE UE CONTEXT REQUEST message.

[0334] Optionally, in addition to being used to request the first context related to the packet data of the remote terminal device, the seventh indication information can also be used to request the Uu-related context of the remote terminal device, wherein the Uu-related context is used to transmit the context of non-packet data of the remote terminal device.

[0335] S710: The second network device sends a first context to the first network device, and the first network device receives the first context from the second network device.

[0336] Optionally, S708 includes: the second network device may send a second Xn interface response message to the first network device, where the second Xn interface response message may include the first context. The second Xn interface response message may be a response message to the second Xn interface request message, for example, the second Xn interface response message may be a RETRIEVE UE CONTEXT RESPONSE message or a PARTIAL UE CONTEXT TRANSFER message.

[0337] Optionally, in some cases, the first network device can obtain the first context of the remote terminal device and the second context of the relay terminal device through an indication message. In this case, S707 and S709 are one step. For example, the first Xn interface request message and the second Xn interface request message can be the same Xn interface request message. The Xn interface request message includes an indication information. The second network device can send the first context of the remote terminal device and the second context of the relay terminal device to the first network device after receiving the indication information. Optionally, the second network device can also send the first context of the remote terminal device and the second context of the relay terminal device to the first network device at the same time after receiving the indication information, and can also send the Uu-related context of the remote terminal device and / or the Uu context of the relay terminal device. In this case, S708 and S710 can be a single step, where the second network device can send the first context and / or Uu-related context of the remote terminal device, as well as the second context of the relay terminal device and / or the Uu context of the relay terminal device, to the first network device. For example, the second network device can send an Xn interface response message to the first network device, where the Xn interface response message can include the first context and / or Uu-related context of the remote terminal device, as well as the second context of the relay terminal device and / or the Uu context of the relay terminal device. This avoids the first network device from separately requesting the context of the relay terminal device and the remote terminal device from the second network device. Optionally, the first network device can directly request the context of the relay terminal device and the context of one or more remote terminal devices connected to the relay terminal device via an indication message. Based on the indication message, the second network device can send the context of the relay terminal device and the context of one or more remote terminal devices connected to the relay terminal device to the first network device, thereby reducing the signaling interaction process between the first and second network devices.

[0338] Optionally, the second network device may determine whether to replace the anchor base station for the relay terminal device. If the second network device determines to replace the anchor base station for the relay terminal device, then in S708, the second network device may send the entire context of the relay terminal device to the first network device. For example, the entire context may include the Uu-related context and the relay-related context of the relay terminal device. For example, the second network device may include the entire context of the relay terminal device in the first Xn interface response message. Optionally, if the second network device determines not to replace the anchor base station for the relay terminal device, then in S708, the second network device may send a partial context of the relay terminal device to the first network device. The partial context may include the second context and / or the configuration information of the Uu RLC channel. For example, the second network device may include the partial context of the relay terminal device in the first Xn interface response message.

[0339] Optionally, in some cases, S707 and S708 may not exist, that is, S707 and S708 are optional steps, that is, the second context of the relay terminal device obtained by S708 is for the relay terminal device to transmit the first packet data with the first network device in the RRC non-connected state. If the relay terminal device transmits the first packet data with the first network device in the RRC connected state, the first network device may not need to obtain the second context.

[0340] Optionally, after S710, S711 may be executed.

[0341] S711: The first network device sends a third RRC response message to the remote terminal device through the relay terminal device, and the remote terminal device receives the third RRC response message through the relay terminal device.

[0342] S712a, same as S513a.

[0343] S713a, the relay terminal device sends a first packet of data to the first network device, and the first network device receives the first packet of data.

[0344] For S713a, reference may be made to the description of S514a, wherein the network device in S514a may be the first network device in S713a.

[0345] Optionally, if the first network device receives the entire context of the relay terminal device from the second network device, it indicates that the mapping base station is changed. After the first network device receives the first packet data from the relay terminal device in S713a, it may not send the first packet data to the second network device.

[0346] Optionally, if the first network device receives a partial context of the relay terminal device from the second network device, it means that the mapping base station will not be changed. After the first network device receives the first packet data from the relay terminal device in S713a, it can send the first packet data to the second network device.

[0347] S712b, the first network device sends a first packet of data to the relay terminal device, and the relay terminal device receives the first packet of data from the first network device.

[0348] For S712b, reference may be made to the description of S513b, wherein the network device in S513b may be the first network device in S712b.

[0349] S713b, same as S513b.

[0350] S714, the first network device sends an RRC release message to the relay terminal device.

[0351] S715: The first network device sends an RRC release message to the remote terminal device through the relay terminal device.

[0352] For S715 , reference may be made to the description of S515 , wherein the network device in S515 may be the first network device in S715 .

[0353] Optionally, in the communication method 700, the first network device may be a target network device or a target base station, and the second network device may be a source network device or a source base station.

[0354] In the aforementioned communication method 700, after the relay terminal device moves from the coverage area of ​​the second network device to the coverage area of ​​the first network device, the first network device may obtain the first context of the remote terminal device and / or the second context of the relay terminal device from the second network device. The first context and the second context are contexts used to transmit packet data of the remote terminal device. In this way, the remote terminal device and the relay terminal device can transmit packet data between the remote terminal device and the first network device even within the coverage area of ​​the first network device.

[0355] Optionally, in the above communication method 700 , the manner in which the first network device obtains the first context and / or the second context from the second network device is also applicable to the communication method 600 , which is not described in detail to avoid redundancy.

[0356] It can be understood that in the embodiment of the present application, when the remote terminal device or the relay terminal device is in the RRC non-connected state, the RRC connection is restored to perform SDT. For the convenience of description, the remote terminal device or the relay terminal device initiates the RRC connection recovery process as an example, and it is not limited to the remote terminal device or the relay terminal device executing the recovery process.

[0357] In an embodiment of the present application, the packet data transmission process may be a packet data transmission process in an RRC non-connected state.

[0358] Figure 8 is a schematic block diagram of a communication device provided in an embodiment of the present application. As shown in Figure 8, the communication device 800 may include a processing unit 810 and a communication unit 820. The communication unit 820 can implement corresponding communication functions, and the communication can be internal communication of the communication device 800 or communication between the communication device 800 and other devices; the processing unit 810 can implement corresponding processing functions. The communication unit 820 can also be called a communication interface or a transceiver unit. Optionally, the communication device 800 may also include a storage unit, which can be used to store instructions and / or data, and the processing unit 810 can read the instructions and / or data in the storage unit so that the device implements the aforementioned method embodiment.

[0359] In one possible design, the communication device 800 may be the remote terminal device described in the communication methods 400, 500, and 600 above, or may be a module or chip applied to the remote terminal device. The communication methods 400, 500, and 600 may be used to execute the steps or processes performed by the remote terminal device in the above-described embodiments.

[0360] Specifically, the processing unit 810 is used to save a first context for transmitting packet data between the remote terminal device and the network device through the relay terminal device; if the transmission conditions of the packet data are met, the first context is restored; and the communication unit 820 is used to transmit the first packet data between the remote terminal device and the network device through the relay terminal device in a non-connected state of wireless resource control RRC based on the restored first context.

[0361] Optionally, the transmission condition includes at least one of the following: the amount of data related to the transmission of small packet data is less than or equal to a first data amount threshold value, the reference signal received power RSRP between the remote terminal device and the relay terminal device is greater than or equal to a first RSRP threshold value, or a first indication information sent by the network device is received, and the first indication information indicates that the network device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state.

[0362] Optionally, the data volume related to packet data transmission includes the size of a PC5 radio link control RLC protocol data unit PDU corresponding to the first packet data and / or the size of a PC5 RLC service data unit SDU corresponding to the first packet data.

[0363] Optionally, the communication unit 820 is also used to initiate a packet data transmission process before transmitting the first packet data between the remote terminal device and the network device through the relay terminal device in the non-connected state of the radio resource control RRC based on the first context recovery, if the transmission conditions of the packet data are met, and send a first RRC request message to the network device through the relay terminal device, the first RRC request message including second indication information, and the second indication information is used to indicate that the remote terminal device has a transmission requirement for packet data.

[0364] Optionally, the communication unit 820 is further used to: if the transmission conditions of the small packet data are met, send second indication information to the relay terminal device, and the second indication information is used to indicate that the remote terminal device has a transmission requirement for the small packet data.

[0365] Optionally, the second indication information is included in information of a media access control MAC layer; or, the second indication information is included in information of a sidelink relay adaptation protocol SRAP layer.

[0366] Optionally, the information of the MAC layer is a MAC control element CE or a MAC subheader, and the information of the SRAP layer is a SRAP subheader or a SRAP protocol data unit PDU.

[0367] Optionally, the communication unit 820 is also used to: before transmitting the first packet data between the remote terminal device and the network device through the relay terminal device in the wireless resource control RRC non-connected state based on the first context recovered, if the transmission conditions of the packet data are met, initiate a packet data transmission process and send a first RRC request message to the network device through the relay terminal device.

[0368] Optionally, the communication unit 820 is further used to: receive third indication information sent by the network device through the relay terminal device, and the third indication information is used to indicate that the network device has successfully received the first RRC request message.

[0369] Optionally, the third indication information is included in information of the media access control MAC layer; or, the third indication information is included in information of the sidelink relay adaptation protocol SRAP layer, or the third indication information is included in information of the RRC layer.

[0370] Optionally, the information of the MAC layer is a MAC control element CE or a MAC subheader, and the information of the SRAP layer is a SRAP subheader, a SRAP data protocol data unit PDU or a SRAP control protocol data unit PDU.

[0371] Optionally, the communication unit 820 is further used to: receive fourth indication information from the relay terminal device, where the fourth indication information is used to indicate that the network device has successfully received the first RRC request message.

[0372] Optionally, the communication unit 820 is also used to: obtain capability information of the relay terminal device, the capability information being used to indicate whether the relay terminal device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state; the communication unit 820 is specifically used to: if the capability information is used to indicate that the relay terminal device supports the remote terminal device transmitting small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state, then sending the first RRC request message to the relay terminal device through the connection with the relay terminal device, the first RRC request message including second indication information.

[0373] Optionally, the communication unit 820 is also used to: obtain capability information of the relay terminal device, the capability information being used to indicate whether the relay terminal device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state; the communication unit 820 is specifically used to: if the capability information is used to indicate that the relay terminal device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state, then send a second indication information to the relay terminal device.

[0374] Optionally, the first context includes first configuration information of a PC5 relay RLC channel and / or a PC5 sidelink relay adaptation protocol SRAP configuration.

[0375] Optionally, the communication unit 820 is specifically used to: send the first packet data to the relay terminal device based on the first configuration information.

[0376] Optionally, the communication unit 820 is specifically used to: send and receive first packet data from the relay terminal device based on the first configuration information.

[0377] Optionally, the relay terminal device is in an RRC connected state, an RRC idle state or an RRC inactive state.

[0378] Optionally, the communication unit 820 is also used to: receive first timer information from the network device, the first timer information being used to indicate the first duration of the first timer for transmitting the packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state; the communication unit 820 is specifically used to: transmit the first packet data between the remote terminal device and the network device through the relay terminal device in the radio resource control RRC non-connected state based on the restored first context within the first duration.

[0379] In one possible design, the communication device 800 may be the relay terminal device described in the communication methods 400, 500, and 600 above, or may be a module or chip applied to the relay terminal device. The communication methods 400, 500, and 600 may be used to execute the steps or processes performed by the relay terminal device in the above-described embodiments.

[0380] Specifically, the communication unit 820 is used to receive a second indication message from a remote terminal device in an RRC non-connected state, wherein the second indication message is used to indicate that the remote terminal device has a transmission requirement for small packet data; the relay terminal device sends the fifth indication message to the network device based on the second indication message in the RRC connected state, wherein the fifth indication message is used to indicate that the remote terminal device has a transmission requirement for small packet data.

[0381] Optionally, the second indication information is included in information of a media access control MAC layer; or, the second indication information is included in information of a sidelink relay adaptation protocol SRAP layer.

[0382] Optionally, the information of the MAC layer is a MAC control element CE or a MAC subheader, or the information of the SRAP layer is a SRAP subheader or a SRAP protocol data unit PDU.

[0383] Optionally, the communication unit 820 is further used to: receive a first radio resource control RRC request message from the remote device; and send the first RRC request message to the network device.

[0384] Optionally, the communication unit 820 is further configured to: receive the first packet data from the remote terminal device; and the processing unit 810 is configured to not discard the first packet data based on the second indication information.

[0385] In one possible design, the communication apparatus 800 may be the first network device in the communication method 700 described above, or may be a module or chip applied to the first network device. The communication methods 400, 500, and 600 may be used to execute the steps or processes executed by the first network device in the above-described embodiments.

[0386] Specifically, the communication unit 820 is used to: send a sixth indication message to the second network device, wherein the sixth indication message is used to request the relay terminal device to transmit the second context of the packet data of the remote terminal device; and transmit the first packet data of the remote terminal device through the relay terminal device based on the requested second context.

[0387] Optionally, the communication unit 820 is also used to: send a seventh indication message to the second network device, wherein the seventh indication message is used to request a first context related to the packet data of the remote terminal device; and transmit the first packet data of the remote terminal device through the relay terminal device based on the requested first context.

[0388] In some possible implementations, the sixth indication information and the seventh indication information are one piece of indication information, or the sixth indication information and the seventh indication information are different pieces of indication information.

[0389] Regarding the steps or processes executed by each unit in the communication device 800, please refer to the above method embodiments for details, which will not be described in detail here.

[0390] It should be understood that the "unit" in the communication device 800 can be implemented by hardware, can be implemented by software, and can also be implemented by hardware executing the corresponding software implementation. For example, the "unit" can refer to an application specific integrated circuit (ASIC), an electronic circuit, a processor (such as a shared processor, a dedicated processor or a group processor, etc.) and a memory for executing one or more software or firmware programs, a combined logic circuit and / or other suitable components that support the described functions. For another example, the communication unit 820 can be replaced by a transceiver transceiver circuit (for example, a receiving circuit and a transmitting circuit), and the processing unit 810 can be replaced by a processor or a processing circuit.

[0391] Figure 9 shows a schematic block diagram of another communication device 900 provided in an embodiment of the present application. The device 900 can be a relay terminal device, a remote terminal device, or a first network device, or can be a chip, a chip system, or a processor that supports the relay terminal device, the remote device, or the first network device to implement the above method. The device can be used to implement the method described in the above method embodiment. For details, please refer to the description of the above method embodiment.

[0392] The device 900 may include one or more processors 910, which may also be referred to as processing units, and may implement certain control functions. The processor 910 may be a general-purpose processor or a dedicated processor. For example, it may be a baseband processor or a central processing unit. The baseband processor may be used to process communication protocols and communication data, and the central processing unit may be used to control a communication device (e.g., a base station, a baseband chip, a user chip, a DU or a CU, etc.), execute software programs, and process data from the software programs.

[0393] In an optional design, the processor 910 may also store instructions and / or data, which can be executed by the processor 910 to enable the device 900 to perform the method described in the above method embodiment. Optionally, the processing unit 810 in the communication device 800 may be the processor 910.

[0394] In another optional design, the device 900 may include a communication interface 920 for implementing receiving and transmitting functions. For example, the communication interface 920 may be a transceiver circuit, an interface, an interface circuit, or a transceiver. The transceiver circuit, interface, interface circuit, or transceiver for implementing the receiving and transmitting functions may be separate or integrated. The transceiver circuit, interface, interface circuit, or transceiver may be used for reading and writing code / data, or the transceiver circuit, interface, interface circuit, or transceiver may be used for transmitting or delivering signals. Optionally, the communication unit 820 in the communication device 800 may be the communication interface 920.

[0395] Optionally, the device 900 may include one or more memories 930, which may store instructions that can be executed on the processor 910, causing the device 900 to perform the method described in the above method embodiment. Optionally, the memory 930 may also store data. Optionally, the processor 910 may also store instructions and / or data. The processor 910 and memory 930 may be provided separately or integrated together.

[0396] Those skilled in the art will appreciate that, for ease of explanation, FIG9 illustrates only one memory and processor. In an actual relay terminal device, remote terminal device, or first network device, multiple processors and memories may exist. A memory may also be referred to as a storage medium or storage device, etc., which is not limited in this embodiment of the present application.

[0397] For example, a processor may include a baseband processor and a central processing unit (CPU). The baseband processor is primarily responsible for processing communication protocols and communication data, while the CPU is primarily responsible for controlling the entire terminal device, executing software programs, and processing data from these programs. The processor in Figure 9 integrates the functions of both a baseband processor and a CPU. Those skilled in the art will appreciate that the baseband processor and the CPU may also be independent processors interconnected via a bus or other technology. Those skilled in the art will appreciate that a terminal device may include multiple baseband processors to accommodate different network standards, multiple CPUs to enhance its processing capabilities, and that the various components of the terminal device may be connected via various buses. The baseband processor may also be referred to as a baseband processing circuit or a baseband processing chip. The CPU may also be referred to as a central processing circuit or a central processing chip. The functionality for processing communication protocols and communication data may be built into the processor or stored as a software program in a storage unit, with the processor executing the software program to implement the baseband processing functionality.

[0398] It should be understood that, in one possible design, each step in the method embodiment provided in the present application can be completed by an integrated logic circuit of the hardware in the processor or by instructions in the form of software. The steps of the method disclosed in conjunction with the embodiments of the present application can be directly embodied as being executed by a hardware processor, or can be executed by a combination of hardware and software modules in the processor. The software module can be located in a storage medium mature in the art, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware. To avoid repetition, it will not be described in detail here.

[0399] It should be noted that the processor in the embodiments of the present application can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiment can be completed by an integrated logic circuit of the hardware in the processor or by instructions in the form of software. The above processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. The various methods, steps, and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor. The steps of the method disclosed in the embodiments of the present application can be directly embodied as being executed by a hardware decoding processor, or can be executed by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium mature in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0400] It is understood that the memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM bus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0401] The present application also provides a computer program product, which includes: computer program code, which, when executed on a computer, enables the computer to execute the various steps or processes executed by the relay terminal device, the remote terminal device, or the first network device in any of the above method embodiments.

[0402] The present application also provides a computer-readable storage medium, which stores program code. When the program code runs on a computer, the computer executes the various steps or processes executed by the relay terminal device or the remote terminal device or the first network device in any of the above method embodiments.

[0403] The present application also provides a communication device, including a processor and an interface, which is used to send and / or receive signals, so that the processor executes the various steps or processes performed by the relay terminal device or the remote terminal device or the first network device in any of the above method embodiments.

[0404] The present application also provides a communication system, which includes at least two of a remote terminal device, a relay terminal device or a first network device.

[0405] The above-mentioned device embodiments and method embodiments are completely corresponding, and the corresponding steps are performed by the corresponding modules or units. For example, the communication unit or communication interface performs the receiving or sending steps in the method embodiment. Other steps except sending and receiving can be performed by the processing unit or processor.

[0406] In the embodiments of this application, each term and English abbreviation is provided for convenience of description and shall not constitute any limitation to this application. This application does not exclude the possibility of defining other terms that can achieve the same or similar functions in existing or future agreements.

[0407] As used in this specification, the terms "component," "module," "system," and the like are used to represent computer-related entities, hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program, and / or a computer. By way of illustration, both an application running on a computing device and a computing device can be a component. One or more components can reside in a process and / or an execution thread, and a component can be located on one computer and / or distributed between two or more computers. In addition, these components can be executed from various computer-readable storage media having various data structures stored thereon. Components can communicate, for example, via local and / or remote processes based on signals having one or more data packets (e.g., data from two components interacting with another component between a local system, a distributed system, and / or a network, such as the Internet interacting with other systems via signals).

[0408] Those skilled in the art will appreciate that the various illustrative logical blocks and steps described in conjunction with the embodiments disclosed herein can be implemented using electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0409] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can be based on the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0410] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0411] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0412] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0413] In the above embodiments, the functions of each functional unit can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When software is used for implementation, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions (programs). When the computer program instructions (programs) are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website, computer, server or data center to another website, computer, server or data center by wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrations. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (eg, a solid state disk (SSD)).

[0414] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0415] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that: Applied to remote terminal devices, including: Saving a first context for transmitting packet data between the remote terminal device and the network device through the relay terminal device; If the transmission condition of the packet data is met, restoring the first context; Based on the restored first context, the first packet data between the remote terminal device and the network device is transmitted through the relay terminal device in a radio resource control RRC non-connected state.

2. The communication method according to claim 1, characterized in that: The transmission condition includes at least one of the following: the amount of data related to the transmission of small packet data is less than or equal to a first data amount threshold value, the reference signal received power RSRP between the remote terminal device and the relay terminal device is greater than or equal to a first RSRP threshold value, or first indication information sent by the network device is received, and the first indication information indicates that the network device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state.

3. The communication method according to claim 2, characterized in that: The data volume related to packet data transmission includes the size of a PC5 radio link control RLC protocol data unit PDU corresponding to the first packet data and / or the size of a PC5 RLC service data unit SDU corresponding to the first packet data.

4. The communication method according to any one of claims 1 to 3, characterized in that: Before the first context based on the recovery transmits the first packet data between the remote terminal device and the network device through the relay terminal device in the radio resource control RRC non-connected state, the communication method further includes: If the transmission conditions of the small packet data are met, a small packet data transmission process is initiated, and a first RRC request message is sent to the network device through the relay terminal device. The first RRC request message includes second indication information, and the second indication information is used to indicate that the remote terminal device has a small packet data transmission requirement.

5. The communication method according to any one of claims 1 to 3, characterized in that: The communication method further comprises: If the transmission condition of the small packet data is met, second indication information is sent to the relay terminal device, and the second indication information is used to indicate that the remote terminal device has a transmission demand for the small packet data.

6. The communication method according to claim 5, characterized in that: The second indication information is included in information of a media access control MAC layer; or, the second indication information is included in information of a sidelink relay adaptation protocol SRAP layer.

7. The method according to claim 6, characterized in that The information of the MAC layer is a MAC control element CE or a MAC subheader, and the information of the SRAP layer is a SRAP subheader or a SRAP protocol data unit PDU.

8. The communication method according to any one of claims 5 to 7, characterized in that: Before the first context based on the recovery transmits the first packet data between the remote terminal device and the network device through the relay terminal device in the radio resource control RRC non-connected state, the communication method further includes: If the transmission conditions of the small packet data are met, a small packet data transmission process is initiated, and a first RRC request message is sent to the network device through the relay terminal device.

9. The communication method according to claim 4 or 8, characterized in that: The communication method further comprises: The third indication information sent by the network device is received through the relay terminal device, and the third indication information is used to indicate that the network device has successfully received the first RRC request message.

10. The communication method according to claim 9, characterized in that: The third indication information is included in the information of the media access control MAC layer; or, the third indication information is included in the information of the sidelink relay adaptation protocol SRAP layer, or the third indication information is included in the information of the RRC layer.

11. The communication method according to claim 10, characterized in that: The information of the MAC layer is a MAC control element CE or a MAC subheader, and the information of the SRAP layer is a SRAP subheader, a SRAP data protocol data unit PDU or a SRAP control protocol data unit PDU.

12. The communication method according to claim 4 or 8, characterized in that: The communication method further comprises: Receive fourth indication information from the relay terminal device, where the fourth indication information is used to indicate that the network device has successfully received the first RRC request message.

13. The communication method according to claim 4 or 12, characterized in that: The communication method further comprises: Acquire the capability information of the relay terminal device, the capability information is used to indicate whether the relay terminal device supports the The remote terminal device transmits the packet data between the remote terminal device and the network device through the relay terminal device in the RRC non-connected state; The sending of the RRC request message to the relay terminal device includes: If the capability information is used to indicate that the relay terminal device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state, then the first RRC request message is sent to the relay terminal device through the connection with the relay terminal device, and the first RRC request message includes second indication information.

14. The communication method according to any one of claims 5 to 8 or 12, characterized in that: The communication method further comprises: Acquire capability information of the relay terminal device, where the capability information is used to indicate whether the relay terminal device supports the remote terminal device to transmit small packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state; The sending of the second indication information to the relay terminal device includes: If the capability information is used to indicate that the relay terminal device supports the remote terminal device in an RRC non-connected state to transmit small packet data between the remote terminal device and the network device through the relay terminal device, then second indication information is sent to the relay terminal device.

15. The communication method according to any one of claims 1 to 14, characterized in that: The first context includes first configuration information of a PC5 relay RLC channel and / or a PC5 sidelink relay adaptation protocol SRAP configuration.

16. The communication method according to claim 15, characterized in that: The first context based on the recovery transmits the first packet data between the remote terminal device and the network device through the relay terminal device in a radio resource control RRC non-connected state, including: Sending the first packet data to the relay terminal device based on the first configuration information; Alternatively, the first context based on the recovery transmits the first packet data between the remote terminal device and the network device through the relay terminal device in a radio resource control RRC non-connected state, including: A first packet of data is sent and received from the relay terminal device based on the first configuration information.

17. The communication method according to any one of claims 1 to 16, characterized in that: The relay terminal device is in RRC connected state, RRC idle state or RRC inactive state.

18. The communication method according to any one of claims 1 to 17, characterized in that: The communication method further comprises: Receive first timer information from the network device, where the first timer information is used to indicate a first duration of a first timer for transmitting packet data between the remote terminal device and the network device through the relay terminal device in an RRC non-connected state; The first context based on the recovery transmits the first packet data between the remote terminal device and the network device through the relay terminal device in a radio resource control RRC non-connected state, including: Within the first time period, based on the restored first context, the first packet data between the remote terminal device and the network device is transmitted through the relay terminal device in a radio resource control RRC non-connected state.

19. A communication device, characterized in that: The method comprises a unit for executing the communication method as claimed in any one of claims 1 to 18.

20. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed, the communication method according to any one of claims 1 to 18 is implemented.

21. A chip, characterized in that: The chip comprises a processor connected to a memory, the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the chip executes the communication method according to any one of claims 1 to 18.

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