Communication method and apparatus

Abstract

A communication method and apparatus, relating to the technical field of wireless communications. The method comprises: a terminal device sends first signaling or receives second signaling in a first state, wherein the first signaling is used for triggering scheduling of uplink data transmission for the terminal device, the second signaling is used for scheduling of downlink data transmission for the terminal device, context information stored by the terminal device in the first state comprises part of context information among context information stored by the terminal device in an RRC connected state, and the part of context information comprises security configuration information.

Description

A communication method and apparatus

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411556021.1, filed on November 1, 2024, entitled "A Communication Method and Apparatus", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of wireless communication technology, and in particular to a communication method and apparatus. Background Technology

[0004] In Long Term Evolution (LTE) systems, the Radio Resource Control (RRC) state of a terminal device includes RRC Connected State and RRC Idle State. In RRC Connected State, there is a signaling connection between the terminal device and the base station, allowing data transmission between them; alternatively, there may be no data transmission but only RRC signaling. In RRC Idle State, there is no signaling connection between the terminal device and the base station; there is neither data transmission nor RRC signaling. When a terminal device is in RRC Idle State, the core network can page the terminal device within the area corresponding to its Tracking Area Identity (TAI) list using one or more base stations within that area. When a terminal device moves out of the area corresponding to the TAI list, a core network registration process can be initiated to perform a non-access stratum (NAS) registration update. The core network registers the location of the terminal device and updates the terminal device registration area, that is, it reassigns a TAI list containing the tracking area (TA) of the cell to which the terminal device is currently located to the terminal device.

[0005] In 5G systems, an RRC inactive state is introduced in addition to the RRC connected and RRC idle states. In the RRC connected state, an RRC connection is established between the terminal device and the base station, and both the terminal device and the base station maintain the terminal device's context information. In the RRC idle state, there is no RRC connection between the terminal device and the base station, and neither the terminal device nor the base station needs to maintain the terminal device's context information. In the RRC inactive state, the terminal device suspends data processing, but the terminal device and the base station still maintain some of the terminal device's context information, allowing the terminal device to quickly return to the RRC connected state.

[0006] Because data processing is paused, terminal devices in the RRC inactive state can maintain a power consumption level similar to that in the RRC idle state. Meanwhile, since the base station still maintains the context information of the terminal devices in the RRC inactive state, the terminal devices remain in the connection management connected (CM-connected) state. This means that the terminal devices still have a signaling connection with the access and mobility management function (AMF). Therefore, when there is a data transmission requirement to migrate the terminal device from the RRC inactive state to the RRC connected state, compared to migrating from the RRC idle state to the RRC connected state, there is no need to carry out establishment and authentication processes, thus allowing for a faster resumption of service for the terminal devices.

[0007] Regarding data transmission, in RRC connected mode, when data transmission is needed, the terminal device can immediately perform data transmission based on the RRC connection, achieving a rapid transition from non-connected transmission to data transmission. In RRC inactive mode, for downlink data transmission, the terminal device needs to receive a paging message during paging and access the network based on the paging message before it can receive data. For uplink transmission, the terminal device needs to restore the RRC connection based on the saved context information before it can send data. Compared to RRC connected mode, the transition time from non-connected transmission to data transmission is slower. In RRC idle mode, since the terminal device does not save context information, it takes longer to establish an RRC connection with the network side compared to restoring the RRC connection with the network side in RRC inactive mode. Therefore, the transition time from non-connected transmission to data transmission is even slower. Regarding energy saving, in RRC connected mode, the terminal device needs to perform channel measurements on periodic reference signals, such as measuring the channel state information reference signal (CSI-RS) with a period of 20 milliseconds, in order to select appropriate bandwidth resources for data transmission with the network side. This results in higher power consumption and poor energy saving. In RRC disconnected mode, the terminal device does not need to perform channel measurements on the reference signal, resulting in lower power consumption and better energy saving. In RRC idle mode, the terminal device achieves the best energy saving. It can be seen that none of the above RRC states can simultaneously achieve both data transmission conversion speed and energy saving.

[0008] Therefore, how to ensure data transmission conversion speed while saving energy is a problem that needs to be solved. Summary of the Invention

[0009] This application provides a communication method and apparatus to ensure data transmission conversion speed while saving energy.

[0010] Some embodiments of this application can be applied to terminal-side devices, which may be terminal devices, modules (such as chips) within terminal devices, or software (such as control subsystems) containing terminal device functions. Other embodiments of this application can be applied to network-side devices, which may be network devices, such as base stations or wireless access network devices. The network-side device may be a network device, a module (such as a chip) within a network device, or software (such as control subsystems) containing network device functions.

[0011] In a first aspect, a communication method is provided, applied to a terminal device. The method includes: in a first state, sending a first signaling or receiving a second signaling, wherein the first signaling is used to trigger the scheduling of uplink data transmission for the terminal device, and the second signaling is used to schedule downlink data transmission for the terminal device; wherein the context information stored by the terminal device in the first state includes a portion of the context information stored by the terminal device in the RRC connection state, and the portion of the context information includes security configuration information.

[0012] In the above implementation, since the terminal device's context information, which is stored in the first state, includes security configuration information, the security of data transmission can be quickly achieved based on this security configuration information. Compared with the fact that a terminal in the RRC inactive state needs to go through the paging process of the network device and the recovery process of the RRC connection to obtain security configuration information, the above implementation of this application can improve the conversion speed from no data transmission to data transmission.

[0013] In one possible implementation, the first signaling is Layer 1 signaling or Layer 2 signaling, for example, the first signaling is a preamble or a scheduling request.

[0014] In one possible implementation, the second signaling is Layer 1 signaling or Layer 2 signaling, for example, the second signaling is downlink control information (DCI).

[0015] In one possible implementation, in the first state, the terminal device stops measuring the periodic reference signal; or, in the first state, the terminal device measures the periodic reference signal, and the length of the measurement period is greater than the length of the measurement period when measuring the periodic reference signal in the RRC connected state or the RRC inactive state; or, in the first state, the terminal device measures the periodic reference signal, and the length of the measurement period is equal to the length of the measurement period when measuring the periodic reference signal in the RRC connected state or the RRC inactive state.

[0016] In the above implementation, since the terminal device releases or suspends air interface context information, periodic measurement configuration information, and other information related to data transmission in the first state, it is not necessary to perform operations related to these context information, thereby achieving energy saving.

[0017] In one possible implementation, before or after sending the first signaling, or after receiving the second signaling, or after receiving the third signaling, the method further includes: obtaining fifth context information; wherein the third signaling is triggered based on the first signaling, and the third signaling is used to schedule uplink data transmission for the terminal device; the fifth context information includes one or more of the following: air interface context information related to data transmission, the air interface context information related to data transmission including data packet sequence number and / or data transmission related variables, the data transmission related variables being used to determine the time window for data transmission; periodic reference signal configuration information and / or measurement reporting configuration information; and a security key.

[0018] In one possible implementation, obtaining the fifth context information includes: deriving the security key in the fifth context information based on the security configuration information in the context configuration information saved by the terminal device in the first state; or, obtaining the periodic reference signal configuration information and / or measurement reporting configuration information in the fifth context information based on the information sent by the network device; or, restoring the suspended fifth context information.

[0019] One possible implementation also includes deleting or suspending the fifth context information when the first condition is met.

[0020] In the above implementation, when certain conditions are met (such as after the uplink data transmission is completed), the fifth context information is deleted or suspended. This can reduce some interaction operations between the network device and the terminal device related to this context information, thereby achieving energy saving. Furthermore, when there is an uplink data transmission requirement, the fifth context information can be quickly obtained to ensure the implementation of uplink data transmission. This can achieve the goal of low power consumption during data transmission and rapid data conversion during data transmission.

[0021] In one possible implementation, deleting or suspending the fifth context information when the first condition is met includes: deleting or suspending the fifth context information after completing the uplink data transmission or the downlink data transmission; or deleting or suspending the fifth context information when the first timer times out; wherein the first timer is started after receiving the third signaling, or after receiving the second signaling; or deleting or suspending the fifth context information after receiving the fourth signaling.

[0022] In one possible implementation, the second signaling is further used to instruct the terminal device to measure the accompanying reference signal, or to indicate that an accompanying reference signal is being transmitted.

[0023] In one possible implementation, the method further includes: receiving downlink data and a reference signal transmitted along with the downlink data according to the second signaling; measuring the reference signal to obtain a measurement result; and transmitting the measurement result. This allows the network device to select appropriate downlink resources for the terminal based on the measurement result, thereby improving the performance and efficiency of downlink transmission.

[0024] In one possible implementation, after the terminal device receives the second signaling in the first state, it further includes: receiving downlink data; and sending a first sequence of a first signal, the first sequence being used to indicate that the terminal device has successfully received the downlink data.

[0025] In one possible implementation, after the terminal device receives the second signaling in the first state, it further includes: sending a second sequence of a first signal, the second sequence being used to indicate that the terminal device has failed to receive downlink data.

[0026] In one possible implementation, the first signal is a preamble or a probe reference signal.

[0027] In one possible implementation, the first signaling is used to access the target cell. The method further includes: receiving a random access response message, optionally, the random access response message indicating uplink resources allocated to the terminal device; and sending Msg3, the Msg3 including uplink data from the terminal device.

[0028] In the above implementation, for uplink data transmission, the uplink data is carried in Msg3, thereby advancing the data transmission into the Msg3 message to achieve fast transmission.

[0029] Optionally, it may also include: cached status information for sending uplink data from the terminal device.

[0030] Secondly, a communication method is provided, applied to a network device. The method includes: receiving a first signaling or sending a second signaling, wherein the first signaling is used to trigger the scheduling of uplink data transmission for a terminal device in a first state, and the second signaling is used to schedule downlink data transmission for the terminal device in the first state; wherein the context information stored by the terminal device in the first state includes a portion of the context information stored by the terminal device in the RRC connection state, and the portion of the context information includes security configuration information.

[0031] In one possible implementation, in the first state, the terminal device stops measuring the periodic reference signal; or, in the first state, the terminal device measures the periodic reference signal, and the length of the measurement period is greater than the length of the measurement period when measuring the periodic reference signal in the RRC connected state or the RRC inactive state; or, in the first state, the terminal device measures the periodic reference signal, and the length of the measurement period is equal to the length of the measurement period when measuring the periodic reference signal in the RRC connected state or the RRC inactive state.

[0032] In one possible implementation, before or after sending the first signaling, or after receiving the second signaling, or after receiving the third signaling, the method further includes: obtaining fifth context information of the terminal device; wherein the third signaling is triggered based on the first signaling, and the third signaling is used to schedule uplink data transmission of the terminal device; the fifth context information includes one or more of the following: air interface context information related to data transmission, the air interface context information related to data transmission including data packet sequence number and / or data transmission related variables, the data transmission related variables being used to determine the time window of data transmission; periodic reference signal configuration information and / or measurement reporting configuration information; and a security key.

[0033] In one possible implementation, obtaining the fifth context information includes: deriving the security key in the fifth context information based on the security configuration information in the context configuration information saved by the terminal device in the first state; or, restoring the suspended fifth context information.

[0034] One possible implementation also includes deleting or suspending the fifth context information when the second condition is met.

[0035] In one possible implementation, deleting or suspending the fifth context information when the second condition is met includes: deleting or suspending the fifth context information after completing the uplink data transmission or the downlink data transmission; or deleting or suspending the fifth context information when the second timer expires; wherein the second timer is started when the third signaling is sent, or when the second signaling is sent; or deleting or suspending the fifth context information when or after sending the fourth signaling, wherein the fourth signaling is used to instruct the terminal device to delete or suspend the fifth context information.

[0036] In one possible implementation, the second signaling is further used to instruct the terminal device to measure the accompanying reference signal, or to indicate that an accompanying reference signal is being transmitted.

[0037] In one possible implementation, after sending the second signaling, the method further includes: sending downlink data; receiving a first sequence of a first signal, the first sequence being used to indicate that the terminal device has successfully received the downlink data.

[0038] In one possible implementation, after sending the second signaling, the method further includes: sending downlink data; receiving a second sequence of the first signal, the second sequence being used to indicate that the terminal device has failed to receive the downlink data.

[0039] In one possible implementation, the first signal is a preamble or a probe reference signal.

[0040] One possible implementation further includes: after the terminal device in the first state accesses the serving cell, sending a first message to the candidate target cell of the terminal device; receiving a second message sent by the candidate target cell according to the first message, the second message including a temporary identifier of the terminal device in the candidate target cell, and / or security configuration information of the terminal device in the candidate target cell; and sending the temporary identifier and / or the security configuration information to the terminal device.

[0041] In one possible implementation, the second message may also include the validity period of the temporary identifier and / or the activation time of the security configuration information.

[0042] One possible implementation further includes sending the context information of the terminal device to the target cell when the terminal device switches from the source cell to the target cell.

[0043] Based on the first or second aspect above, in one possible implementation, the security configuration information includes one or more of the following: next-hop chain calculation, security key.

[0044] Based on the first or second aspect described above, in one possible implementation, the context information stored by the terminal device in the first state further includes first context information and / or second context information; wherein, the first context information includes data packet sequence number and / or data transmission related variables, the data transmission related variables being used to determine the time window for data transmission; the second context information includes one or more of the following: air interface key, header compression status, compression related context, uplink data compression status, Quality of Service (QoS) and data radio bearer mapping relationship, application layer measurement configuration information, temporary terminal device identifier used by the terminal device in the source cell, physical cell identifier of the source cell, and globally unique cell identifier of the source cell.

[0045] Based on the first or second aspect above, in one possible implementation, the context information stored by the terminal device in the first state further includes third context information, which includes one or more of the following: the temporary identifier of the terminal device in the candidate target cell; or the security configuration information of the terminal device in the candidate target cell.

[0046] Based on the first or second aspect above, in one possible implementation, the third context information further includes one or more of the following: the validity period of the temporary identifier; or, the activation time of the security configuration information.

[0047] Thirdly, a communication method is provided, which is applied to a terminal device. The method includes: receiving downlink data; and sending a first sequence of a first signal, wherein the first sequence is used to indicate that the terminal device has successfully received the downlink data.

[0048] One possible implementation further includes: sending a second sequence of a first signal, the second sequence being used to indicate that the terminal device has failed to receive downlink data.

[0049] In one possible implementation, the first signal is a preamble or a probe reference signal.

[0050] In one possible implementation, before receiving downlink data, the method further includes receiving a second signaling, which is used to schedule downlink data transmission for the terminal device.

[0051] In one possible implementation, the terminal device is in a first state. The context information stored by the terminal device in the first state includes a portion of the context information stored by the terminal device in the RRC connection state, and the portion of the context information includes security configuration information.

[0052] In one possible implementation, in the first state, the terminal device stops measuring the periodic reference signal; or, in the first state, the terminal device measures the periodic reference signal, and the length of the measurement period is greater than the length of the measurement period when measuring the periodic reference signal in the RRC connected state or the RRC inactive state; or, in the first state, the terminal device measures the periodic reference signal, and the length of the measurement period is equal to the length of the measurement period when measuring the periodic reference signal in the RRC connected state or the RRC inactive state.

[0053] Fourthly, a communication apparatus is provided, comprising a unit or module for performing the method described in any one of the first, second, or third aspects.

[0054] Fifthly, a communication apparatus is provided, comprising: one or more processors configured to perform the method described in any one of the first to third aspects.

[0055] A sixth aspect provides a readable storage medium storing a program or instructions that, when executed on a device, cause the device to perform the method described in any one of the first to third aspects.

[0056] A seventh aspect provides a chip system including a processor for supporting a computer device in implementing the method described in any one of the first to third aspects.

[0057] Eighthly, a computer program product is provided, the computer program product comprising a program; when the computer program is run on a computer, the computer causes the computer to perform the method described in any one of the first to third aspects.

[0058] Ninth aspect, a communication system is provided, including a network device and a terminal device, wherein the terminal device performs the method described in any one of the first aspects, and the network device performs the method described in any one of the third aspects. Attached Figure Description

[0059] Figure 1 is a schematic diagram of the architecture of the communication system used in the embodiments of this application;

[0060] Figure 2 is a schematic diagram of the RAN node protocol stack in an embodiment of this application;

[0061] Figure 3 is a schematic diagram of the O-RAN structure in an embodiment of this application;

[0062] Figure 4 is a schematic diagram of the state transitions between the RRC connected state, the RRC idle state and the RRC inactive state in an embodiment of this application;

[0063] Figure 5 is a schematic diagram of the state transitions between the RRC connected state, the RRC idle state and the first state in an embodiment of this application;

[0064] Figure 6 is a schematic diagram of the state transitions between the RRC connected state, RRC idle state, RRC inactive state and the first state in an embodiment of this application;

[0065] Figure 7 is a schematic diagram of an uplink data transmission process provided in an embodiment of this application;

[0066] Figure 8 is a schematic diagram of another uplink data transmission process provided in an embodiment of this application;

[0067] Figure 9 is a schematic diagram of another uplink data transmission process provided in an embodiment of this application;

[0068] Figure 10 is a schematic diagram of a downlink data transmission process provided in an embodiment of this application;

[0069] Figure 11 is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0070] Figure 12 is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0071] The embodiments of this application can be applied to various communication systems, such as: Global System for Mobile Communications (GSM) system, Code Division Multiple Access (CDMA) system, Wideband Code Division Multiple Access (WCDMA) system, General Packet Radio Service (GPRS), Long Term Evolution (LTE) system, LTE Frequency Division Duplex (FDD) system, LTE Time Division Duplex (TDD) system, Universal Mobile Telecommunication System (UMTS), Worldwide Interoperability for Microwave Access (WIMAX) communication system, 5th Generation (5G) system, or New Radio (NR), or applied to future communication systems or other similar communication systems, etc.

[0072] Referring to Figure 1, which is a schematic diagram of the architecture of the communication system 1000 used in the embodiments of this application. As shown in Figure 1, the communication system includes a wireless access network 100 and a core network 200. Optionally, the communication system 1000 may also include the Internet 300. The wireless access network 100 may include at least one wireless access network device (110a and 110b in Figure 1) and at least one terminal device (120a-120j in Figure 1). The terminal device is wirelessly connected to the wireless access network device, and the wireless access network device is wirelessly or wiredly connected to the core network. The core network device and the wireless access network device may be independent physical devices, or the functions of the core network device and the logical functions of the wireless access network device may be integrated on the same physical device, or a single physical device may integrate some of the functions of the core network device and some of the functions of the wireless access network device. Terminal devices and wireless access network devices may be interconnected via wired or wireless means. Figure 1 is just a schematic diagram. The communication system may also include other network devices, such as wireless relay devices and wireless backhaul devices, which are not shown in Figure 1.

[0073] Network devices and terminal devices can be fixed in location or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; and they can be deployed on aircraft, balloons, and artificial satellites. The embodiments of this application do not limit the application scenarios of the network devices and terminal devices.

[0074] The roles of network devices and terminal devices can be relative. For example, the helicopter or drone 120i in Figure 1 can be configured as a mobile network device. For terminal devices 120j that access the wireless access network 100 through 120i, drone 120i is a network device; however, for network device 110a, 120i is a terminal device, meaning that 110a and 120i communicate via a wireless air interface protocol. Of course, 110a and 120i can also communicate via a network device-to-network device interface protocol. In this case, relative to 110a, 120i is also a network device. Therefore, both network devices and terminal devices can be collectively referred to as communication devices. 110a and 110b in Figure 1 can be called communication devices with network device functions, and 120a-120j in Figure 1 can be called communication devices with terminal device functions.

[0075] Communication between network devices and terminal devices, between network devices, and between terminal devices can be conducted using licensed spectrum, unlicensed spectrum, or both simultaneously. Communication can be conducted using spectrum below 6 GHz, spectrum above 6 GHz, or both simultaneously. The embodiments of this application do not limit the spectrum resources used for wireless communication.

[0076] In the embodiments of this application, the functions of the network device can be executed by modules (such as chips) within the network device, or by a control subsystem that includes network device functions. This control subsystem, including network device functions, can be a control center in the aforementioned application scenarios such as smart grids, industrial control, intelligent transportation, and smart cities. Similarly, the functions of the terminal device can be executed by modules (such as chips or modems) within the terminal device, or by a device that includes terminal device functions.

[0077] In this embodiment, the network device sends downlink signals or downlink information to the terminal device, with the downlink information carried on the downlink channel; the terminal device sends uplink signals or uplink information to the base station, with the uplink information carried on the uplink channel. In order to communicate with the network device, the terminal device needs to establish a wireless connection with a cell controlled by the network device. The cell with which the terminal device has established a wireless connection is called the serving cell of that terminal device.

[0078] Terminal equipment 120a-120j can be terminal equipment, user equipment (UE), mobile station, mobile terminal, access terminal, UE unit, UE station, mobile station, remote station, remote terminal, mobile device, UE terminal, terminal, wireless communication equipment, multimedia equipment, streaming media equipment, UE agent, or UE device, etc. Access terminals can be cellular phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), handheld devices with wireless communication capabilities, computing devices or other processing devices connected to a wireless modem, vehicles, in-vehicle equipment, wearable devices, drones, helicopters, airplanes, ships, robots, robotic arms, smart home devices, terminal equipment in future 5G networks, or terminal equipment in future evolved public land mobile networks (PLMNs), etc. Terminal devices can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, and smart cities. The embodiments of this application do not limit the specific technologies or device forms used in the terminal devices.

[0079] Wireless access network (RAN) equipment, also known as access network equipment, RAN, RAN entity, RAN node, or access node, constitutes part of a communication system and is used to help terminal devices achieve wireless access and communicate with them. Multiple RANs in the communication system 1000 can be nodes of the same type or different types.

[0080] RAN nodes can be base stations, evolved NodeBs (eNodeBs), relay stations, access points (APs), transmission reception points (TRPs), next-generation NodeBs (gNBs), base stations in future mobile communication systems, access nodes in wireless fidelity (Wi-Fi) systems, or access network equipment in future evolved PLMN networks. RAN nodes can be macro base stations (as shown in Figure 1, 110a), micro base stations or indoor stations (as shown in Figure 1, 110b), relay nodes or donor nodes, or radio controllers in cloud radio access network (CRAN) scenarios, or open RAN (O-RAN or ORAN). Optionally, RAN nodes can also be servers, wearable devices, vehicles, or in-vehicle equipment. For example, access network equipment in vehicle-to-everything (V2X) technology can be roadside units (RSUs).

[0081] RAN nodes can be applied to cellular systems related to the 3rd generation partnership project (3GPP), such as 4G or 5G mobile communication systems, non-terrestrial network (NTN) systems, or future-oriented evolution systems (such as 6G mobile communication systems), as well as communication systems that integrate two or more of the above systems.

[0082] In the NTN system, the RAN node can be in transparent mode or regenerative mode, and its corresponding cell can be an earth fixed cell or an earth moving cell.

[0083] Communication between access network devices and terminal devices follows a specific protocol layer structure. This protocol layer may include a control plane protocol layer and a user plane protocol layer. The control plane protocol layer may include at least one of the following: radio resource control (RRC) layer, packet data convergence protocol (PDCP) layer, radio link control (RLC) layer, media access control (MAC) layer, or physical (PHY) layer, etc. The user plane protocol layer may include at least one of the following: service data adaptation protocol (SDAP) layer, PDCP layer, RLC layer, MAC layer, or PHY layer, etc.

[0084] In scenarios where multiple RAN nodes collaborate to assist terminal devices in achieving wireless access, different RAN nodes can each implement some of the base station's functions. For example, as shown in Figure 2(a), a RAN node can be a central unit (CU), a distributed unit (DU), or a radio unit (RU), etc. As another example, as shown in Figure 2(b), a CU can be split into a CU-control plane (CP) and a CU-user plane (UP). CU and DU can be configured separately or included in the same network element, such as a baseband unit (BBU). CU and DU separate the protocol layers of the RAN node; some protocol layer functions are centrally controlled by the CU, while the remaining partial or complete protocol layer functions are distributed in the DU, which is centrally controlled by the CU. As one implementation, the CU deploys the RRC, SDAP, and PDCP layers from the protocol stack; the DU deploys the RLC, MAC, and PHY layers from the protocol stack. Based on this deployment, the CU has the processing capabilities for RRC, PDCP, and SDAP. DU has RLC, MAC, and PHY processing capabilities.

[0085] RAN nodes communicate with the core network (CN) via backhaul links and with terminal devices via air interfaces. For example, a BBU communicates with the CN via backhaul, and an RU communicates with at least one terminal device via the air interface. A BBU also communicates with at least one RU via a fronthaul link; BBUs and RUs may or may not be co-located. CUs and DUs within a BBU can communicate via midhaul links.

[0086] It is understood that the above functional division is only an example and does not constitute a limitation on CU and DU. RU can be included in radio frequency equipment or radio frequency units, such as in remote radio units (RRU), active antenna units (AAU), or remote radio heads (RRH).

[0087] O-RAN aims to achieve an intelligent and open access network. A key feature of the O-RAN architecture is the separation of hardware and software, enabling the virtualization of network functions and the standardization of hardware. Furthermore, O-RAN incorporates artificial intelligence (AI).

[0088] Figure 3 illustrates a schematic diagram of an O-RAN architecture. In an O-RAN system, a CU can also be called an O-CU (Open CU), a DU can also be called an O-DU, a CU-CP can also be called an O-CU-CP, a CU-UP can also be called an O-CU-UP, and an RU can also be called an O-RU. In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, the meaning of which will be understood by those skilled in the art. Any of the units among CU (or CU-CP, CU-UP), DU, and RU in the embodiments of this application can be implemented through a software module, a hardware module, or a combination of software and hardware modules.

[0089] In some examples, the O-RAN may not contain the O-CU, but only the O-DU.

[0090] The O-CU connects to the O-DU through interfaces such as the F1 interface. In some examples, these interfaces (e.g., the F1 interface) can provide control plane (C-Plane) and user plane (U-Plane) functions, such as interface management, system information management, terminal device context management, and RRC message transmission.

[0091] The CU-CP can interact with network elements in the core network used to implement control plane functions. These control plane elements can be access and mobility function (AMF) elements, such as the AMF in a 5G system, responsible for mobility management in the mobile network, including terminal device location updates, terminal device registration, and terminal device handover. The CU-UP can interact with network elements in the core network used to implement user plane functions. These user plane elements, such as the UPF in a 5G system, are responsible for data forwarding and receiving in terminal devices. The RU communicates with one or more terminal devices via a radio link.

[0092] The above configurations of O-CU and O-DU are merely examples; the functions of O-CU and O-DU can be configured as needed. For instance, O-CU or O-DU can be configured to have more protocol layer functions, or to have only some protocol layer functions. For example, some functions of the RLC layer and the protocol layer functions above the RLC layer can be placed in the CU, while the remaining functions of the RLC layer and the protocol layer functions below the RLC layer can be placed in the O-DU. Furthermore, the functions of O-CU or O-DU can be divided according to service type or other system requirements. For example, based on latency, functions that require low latency can be placed in the O-DU, while functions that do not require low latency can be placed in the O-CU.

[0093] O-DU and RU can be co-located or separate. O-DU and RU exchange control plane and user plane information via a fronthaul link through a Lower-Layer Split CUS-Plane (LLS-CUS) interface. LLS-CUS may include LLS-C and LLS-U interfaces providing the control plane (C-Plane) and user plane (U-Plane), respectively. In some examples, the control plane (C-Plane) refers to real-time control between the O-DU and RU. O-DU and RU exchange management information via an LLS-M interface on the fronthaul link; the management plane (M-Plane) refers to non-real-time management operations between the O-DU and RU. O-DU and RU can cooperate to implement PHY layer functions. One O-DU can be connected to one or more RUs. The functions of the O-DU and RU can be configured in various ways depending on the design. For example, the O-DU may be configured to implement baseband functions, and the RU may be configured to implement mid-RF functions. For example, the O-DU is configured to implement higher-level functions in the PHY layer, and the O-RU is configured to implement lower-level functions in the PHY layer or to implement both lower-level functions and radio frequency functions.

[0094] Table 1 shows the correspondence between network elements (or nodes) in the O-RAN system and their achievable protocol layer functions.

[0095] Table 1: Correspondence between O-RAN network elements and their achievable protocol layer functions

[0096] In the system control plane protocol stack, the protocol layers at and below the RRC layer are called access stratum (AS), and the protocol layers above the RRC layer are called non-access stratum (NAS). Simply put, the AS process refers to the process that requires the participation of both the terminal device and the base station; the NAS process refers to the process that requires the terminal device and the core network to process, with the base station only forwarding the data and not performing any processing. Different protocol layers define different layer states, such as NAS layer states and RRC layer states. Generally, mobility management is usually based on the RRC layer state of the terminal device (hereinafter referred to as RRC state).

[0097] The RRC status of a terminal device reflects its AS connection status. An AS connection refers to the signaling connection between the terminal device and the base station; it is also called an RRC connection. Through AS signaling interaction, a signaling path can be established between the terminal device and the core network. Based on this signaling path, NAS signaling interaction between the terminal device and the core network can be guaranteed.

[0098] In the current communication protocol, terminal devices have different states, and transitions between different RRC states are possible. Figure 4 illustrates a schematic diagram of RRC state transitions. As shown in Figure 4, a terminal device in the RRC connected state initiates an RRC connection release process based on a received RRC Release message, thereby switching to the RRC idle state or the RRC inactive state. Terminal devices in the RRC idle state or the RRC inactive state switch to the RRC connected state through a random access procedure. For a terminal device in the RRC connected state, if the RRC Release message contains a suspendConfig, the terminal device enters the RRC inactive state after the RRC connection is released; if the RRC Release message does not contain suspendConfig, the terminal device enters the RRC idle state after the RRC connection is released. The suspendConfig contains inactive-radio network temporary identity (I-RNTI), RAN-NotificationAreaInfo, RAN paging cycle, T380 timer, and other information, which are used for paging in the RRC inactive state and RAN-based notification area (RNA) updates.

[0099] To ensure data transmission conversion speed while saving energy, embodiments of this application provide a communication method and related apparatus for implementing the method. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0100] This application provides a new RRC state, referred to as the first state in the following embodiments. The first state can be called an energy-saving state (ES), a lightly connected state, or a first mode, etc. If it is called a mode, it can belong to a certain state in the current RRC state, such as a mode under the connected state or the inactive state. This application does not limit the naming of this new RRC state. For ease of description, the first state is used as an example below.

[0101] In this embodiment of the application, when the terminal device is in the first state, the context information of the terminal device stored by the terminal device and the network device is kept synchronized, and may be part of the context information stored by the terminal device when it is in the RRC connection state.

[0102] In some embodiments of this application, when the terminal device is in a first state, the context of the terminal device stored by the terminal device and the network device includes security configuration information (or security context). This security configuration information can be used in the data transmission process, specifically, to ensure the security of the data transmission process.

[0103] In one possible implementation, the security configuration information can be used to derive the security key used for data transmission. For example, the security configuration information can derive the key and / or encryption key used for integrity protection. For instance, the security configuration information may include nextHopChainingCount (NCC), and the terminal device and network device can derive at least one of the following based on the NCC: the complete data plane key K_{UP,int}, the data plane encryption key K_{UP,enc}, the control plane encryption key K_{CP,enc}, and the control plane integrity protection key.

[0104] In another possible implementation, the security configuration information includes security keys, such as keys for integrity protection and / or encryption keys.

[0105] Optionally, the terminal device and network device may retain the security key used by the terminal device in the source cell while the terminal device is stationed there. When the terminal device switches from the source cell to a new cell, it can deduce the security key used in the new cell based on its security configuration information, or obtain the security key used by the terminal device in the new cell through other means.

[0106] Since the terminal device, when in the first state, stores security configuration information in the context information of the terminal device and the network device, the security of data transmission can be quickly achieved based on this security configuration information. For example, a security key for data transmission can be derived from the NCC. Compared with the terminal in the RRC inactive state, which needs to go through the paging process of the network device and the recovery process of the RRC connection to obtain security configuration information, the above implementation method of this application can improve the conversion speed from no data transmission to data transmission.

[0107] In the first state, the context information of the terminal device stored by the terminal device and the network device may include, in addition to the security configuration information mentioned above, first context information and / or second context information.

[0108] Optionally, the first context information includes air interface context information related to data transmission. For example, the first context information may include one or more of the following: packet sequence number, and data transmission-related variables. The data transmission-related variables are used by the terminal device to determine the time window for data transmission. The terminal device can determine the time window in which data transmission occurs (e.g., determine the position and / or length of the time window) based on the data transmission-related variables, so as to perform data transmission within that time window, such as receiving downlink data or sending uplink data within that time window.

[0109] Optionally, if the security configuration information does not include a security key, the first context information may also include the security key. Alternatively, if the security configuration information includes a portion of the security key, the first context information may also include the remaining portion of the security key. For example, if the security configuration information includes a first security key but not a second security key, then the first context information includes the second security key. The first security key may include a portion of the data plane complete key K_{UP,int}, the data plane encryption key K_{UP,enc}, and the control plane encryption key K_{CP,enc}, and the second security key may include the remaining portion of the data plane complete key K_{UP,int}, the data plane encryption key K_{UP,enc}, and the control plane encryption key K_{CP,enc}.

[0110] Optionally, the second context information includes one or more of the following: air interface key, header compression status, compression-related context, uplink data compression (UDC) status, quality of service (QoS) and data radio bearer mapping relationship, application layer measurement configuration information, temporary terminal equipment identifier used by the terminal equipment in the source cell, physical cell identifier of the source cell, and globally unique cell identifier of the source cell. The temporary terminal equipment identifier may, for example, be a cell radio network temporary identifier (C-RNTI).

[0111] Optionally, when the terminal device is in the first state, the context information of the terminal device stored by the terminal device and the network device may also include third context information. The third context information includes one or more of the following: a temporary identifier of the terminal device in the candidate target cell, which may be, for example, a C-RNTI; and security configuration information of the terminal device in the candidate target cell, which may include, for example, NCC and / or a security key. This candidate target cell related information can be obtained from the candidate cell.

[0112] Optionally, the third context information may also include the validity period of the temporary identifier, which is valid for that period. Optionally, the validity period may be predefined.

[0113] Optionally, the third context information may also include the activation time of the security configuration information, which becomes effective after that activation time. Optionally, this activation time may be predefined or configured by the network device.

[0114] Optionally, the third context information may also include an expiration time, which may indicate that the third context information expires after a certain period of time following its receipt. For example, the expiration time may be a duration value, indicating that the third context information expires after a corresponding duration following its receipt. Alternatively, the expiration time may be a time value, indicating that the third context expires when that time is reached.

[0115] The aforementioned candidate target cells may be configured for the terminal device by the serving network equipment (e.g., the serving base station). These candidate target cells may be configured in the form of a cell list. The candidate target cells may include neighboring cells of the cell currently in which the terminal device is located, or other cells that the terminal device may switch to.

[0116] In one possible implementation, the third context information can be configured by the candidate target cell (or the network device corresponding to the candidate target cell). For example, after the terminal device accesses the serving cell, the first network device (i.e., the network device to which the serving cell belongs) can send a first message to the second network device (i.e., the network device to which the candidate target cell belongs) based on the candidate target cell configured for the terminal device. The first network device can obtain the third context information of the terminal device (e.g., the terminal device temporary identifier and / or security configuration information of the terminal device in the candidate target cell when in the first state) from the second network device based on the interface between network devices, and then send it to the terminal device. Optionally, if the first network device determines that the terminal device is accessed and in the first state, it sends the first message to the second network device and receives a second message sent by the second network device, obtaining the third context information of the terminal device carried in the second message.

[0117] When the terminal device is in RRC connected state, both the terminal device and the network device save the aforementioned first context information. When the terminal device is in RRC inactive state, both the terminal device and the network device save the aforementioned second context information. Therefore, in the first state, the context information saved by the terminal device and the network device can be obtained by adding some context information (such as security configuration information, and optionally, third context information) to the context information saved when the terminal device is in RRC inactive state; or, in the first state, the context information saved by the terminal device and the network device can be obtained by subtracting some context information from the context information saved when the terminal device is in RRC connected state, or by subtracting some context information and adding third context information to the context information saved in RRC connected state.

[0118] In some embodiments of this application, the context information of a terminal device in a first state can be migrated to a new cell as the terminal device moves. Specifically, when the terminal device is in the first state, if the terminal device switches from a source cell to a target cell, the source cell (or the network device to which the source cell belongs) sends the stored context information of the terminal device to the target cell (or the network device to which the target cell belongs).

[0119] Optionally, the terminal device can determine the target cell based on the measurement of the downlink reference signal and send an access request or update indication to the target cell. The target cell sends a UE change cell indication to the source cell. The UE change cell indication is used to instruct the terminal device to switch from the source cell or change to the target cell. It can also trigger the source cell to send the current context information of the terminal device stored in the source cell to the target cell.

[0120] Optionally, the source cell or target cell may determine to hand over the terminal device to the target cell based on measurements of the uplink reference signal transmitted by the terminal device. The source cell or target cell sends a handover request to the terminal device, which instructs the terminal device to hand over or change to the target cell and provides relevant configurations to the target cell. The source cell may also send the current context information of the terminal device stored in the source cell to the target cell.

[0121] The context information for migrating from the source cell to the target cell can be all the context information of the terminal device in the first state. If some of the context information of the terminal device is suspended in the first state, the context information for migrating from the source cell to the target cell can include this suspended context information, and this suspended context information is maintained in the target cell.

[0122] The above process can occur when the source cell and the target cell belong to the same area (e.g., the same tracking area). That is, when the terminal device is in the first state and moves between different cells in the same area, the context information of the terminal device can move with the terminal device, migrating from the source cell to the target cell, so as to ensure that when the terminal device needs to transmit data, it can quickly switch from no data transmission to data transmission based on the context information.

[0123] Optionally, the target cell may be one of the candidate target cells, or it may be another cell other than the candidate target cells.

[0124] In one possible implementation, the terminal device, in the first state, can detect the downlink reference signal periodically transmitted by the network side. During data transmission, it can send the detection results (e.g., channel state information) to the network side, or it may not need to report the measurement results when there is no data transmission. Optionally, unlike the RRC connected state, the detection period of the downlink reference signal in the first state can be longer than the detection period in the RRC connected state or the RRC inactive state to save power. For example, in the first state, the context configuration information stored by the terminal device may include periodic reference signal configuration information and / or measurement reporting configuration information, etc. Optionally, the detection period length indicated by the periodic reference signal configuration information is greater than the detection period length in the RRC connected state or the RRC inactive state. Optionally, the reporting period length indicated by the measurement reporting configuration information is greater than the reporting period length in the RRC connected state or the RRC inactive state.

[0125] Optionally, the measurement may include, for example, a Layer 1 or Layer 3 measurement. For instance, the downlink reference signal periodically transmitted by the network side may be a Layer 1 or Layer 3 reference signal, specifically including a channel state information reference signal (CSI-RS), and more specifically, a CSI-RS with a period of 20 milliseconds.

[0126] In another possible implementation, unlike the RRC connected state, the terminal device in the first state does not need to (or rather, stops) detect the downlink reference signal periodically transmitted by the network side. This can be achieved by releasing or suspending the periodic measurement configuration information when the terminal device switches from the RRC connected state to the first state.

[0127] Since the terminal device in the first state does not need to monitor the periodic downlink reference signal, it also does not need to perform channel measurements based on the periodic downlink reference signal or report the measurement results to the network side, thus saving power consumption. Optionally, for the network device, since the terminal device in the first state does not need to monitor the periodic downlink reference signal, the network device does not need to send the downlink reference signal to the terminal device in the first state, thus saving power consumption.

[0128] Optionally, the terminal device can perform uplink measurements (e.g., send uplink reference signals, which the network device can measure) or downlink measurements (e.g., measure and report downlink reference signals) under network-side control, or switch between uplink and downlink measurements.

[0129] Thus, in some scenarios, terminal devices in the first state do not need to periodically transmit uplink reference signals, thereby saving power consumption. Optionally, for network devices, since terminal devices in the first state do not need to periodically transmit uplink reference signals, network devices also do not need to perform channel measurements based on these uplink reference signals, thereby saving power consumption.

[0130] In other scenarios, even in the first state, the terminal device can send periodic uplink signals (e.g., uplink reference signals) to the network device, which can then detect these uplink reference signals. For example, the periodic uplink reference signal sent by the terminal device may include a sounding reference signal (SRS). This application does not limit the type of reference signal. Optionally, unlike the RRC connection state, the period for sending the uplink reference signal in the first state can be longer than the period in the RRC connection state to save power. For example, in the first state, the context configuration information stored by the terminal device may include periodic reference signal configuration information. Optionally, the transmission period length of the uplink reference signal indicated by this periodic reference signal configuration information is greater than the transmission period length in the RRC connection state.

[0131] In one possible implementation, for a terminal device in the first state, the network device can transmit a reference signal along with the path. Correspondingly, the terminal device can receive the reference signal transmitted along with the path by the network device, perform channel measurement based on the reference signal, and the result of the channel measurement can be used to select appropriate resources for subsequent data transmission.

[0132] One example of the aforementioned "network device can transmit reference signals along with the path" is that the reference signal is transmitted along with downlink data; for example, the reference signal is transmitted along with control signaling. Another example is that downlink control signaling transmitted by the network device can be used as an aperiodic reference signal. Downlink data (or control signaling) and the accompanying reference signal can be transmitted on the same channel or on different channels, and this application does not impose any restrictions on this.

[0133] For example, taking the transmission of a reference signal along with downlink data as an example, the network device can transmit a reference signal to the terminal device in the first state on the accompanying channel. The accompanying channel shares the same physical channel as the service channel used to transmit service data. For instance, one implementation of transmitting the downlink reference signal along with downlink data transmission could be that the network device transmits downlink data and the reference signal on different time-frequency resources on the PDSCH. For example, the downlink reference signal could be transmitted on a portion of the frequency domain resources of the first symbol or the first two symbols of the time-frequency resources corresponding to the PDSCH, while the remaining time-frequency resources are used to carry downlink data. In other words, the downlink reference signal occupies a portion of the resources of the downlink data channel. For example, this transmitted downlink reference signal could be CSI-RS.

[0134] For another example, consider a network device sending downlink control signaling and a reference signal sent along with it. The downlink control signaling can be a paging message, activation message, or wake-up message, etc., and the downlink control signaling can be a channel status information reference signal for tracking (TRS). Optionally, the time-domain positions of the downlink control signaling and the reference signal meet certain rules. For example, at least one TRS exists within a first time window before the paging event, and the time interval between the paging event and the first time window can be one or two time slots. The time-domain position of the TRS can be determined based on the time-domain position of the paging event.

[0135] This application does not limit the implementation method of transmitting downlink reference signals along with the network. The terminal device in the first state can monitor the downlink reference signal transmitted along with the network during downlink data transmission, and can perform channel measurement based on the downlink reference signal, and send the measurement results to the network side to improve the transmission efficiency of subsequent data transmission.

[0136] Since the network device only sends downlink data and the accompanying reference signal to the terminal device in the first state when there is a downlink data transmission requirement, and the terminal device measures the accompanying reference signal accordingly, the terminal device in the first state can reduce power consumption compared to the terminal device in the RRC connection state, which needs to monitor and measure the periodic downlink reference signal.

[0137] In this embodiment, the terminal device in the first state supports data transmission. For example, the terminal device in the first state can perform downlink data transmission and / or uplink data transmission based on signaling sent by the network side for data transmission scheduling. The specific implementation method of data transmission by the terminal device in the first state can be referred to the flowcharts shown in Figures 7 to 9.

[0138] In one possible implementation, the first state includes a first mode and / or a second mode. The first mode supports data transmission, or in other words, the terminal device is in the first mode when transmitting data; that is, the terminal device can transmit data in the first mode. The second mode does not support data transmission, or in other words, there is no data transmission in this mode; that is, the terminal device cannot transmit data or does not transmit data in the second mode.

[0139] In one possible implementation, in the second mode, the terminal device and network device store less context information about the terminal device than they did in the first mode. That is, when the terminal device changes from the first mode to the second mode, it can release or suspend a portion of the context information. Correspondingly, when the terminal device changes from the second mode to the first mode, it can restore this released or suspended context information. For ease of description, the context information released or suspended when changing from the first mode to the second mode is referred to as the fourth context information.

[0140] Optionally, the fourth context information may include air interface context information related to data transmission. For example, the fourth context information may include one or more of the following: security key, packet sequence number, and data transmission related variables.

[0141] In another possible implementation, the context information saved when the terminal device is in the first mode is the same as the context information saved when the terminal device is in the second mode. Optionally, in certain scenarios, such as time alignment timer (TA timer) timeout or key update, the context information can be updated so that in the second mode, the terminal device and network device save less context information about the terminal device than in the first mode.

[0142] In one possible implementation, a first search space configuration information is applied in a first mode, and a second search space configuration information is applied in a second mode. The search period length indicated by the first search space configuration information is shorter than the search period length indicated by the second search space configuration information. This allows for a longer search period in the second mode to obtain possible signaling for data transmission scheduling, thus saving power consumption of the terminal device compared to the first mode.

[0143] The terminal device can switch between a first mode and a second mode. For example, depending on whether there is a data transmission requirement, the terminal device can switch between a first mode and a second mode, thereby reducing power consumption when there is no data transmission requirement and quickly switching to a state where data transmission can be performed when there is a data transmission requirement.

[0144] In one possible implementation, the terminal device can switch between a first mode and a second mode according to the instructions of the network device. Specifically, when the terminal device is in the first mode, it can perform data transmission. In the first mode, the network device can send a fifth indication message to the terminal device, which instructs the terminal device to change from the first mode to the second mode, or indicates that data transmission is complete. After receiving the fifth indication message, the terminal device can change from the first mode to the second mode accordingly; correspondingly, the network device can also synchronously change the RRC status of the terminal device before or after sending the fifth indication message. For a terminal device in the second mode, the network device can send a sixth indication message to the terminal device, which allows the terminal device to change from the second mode to the first mode; correspondingly, the network device can also synchronously change the RRC status of the terminal device before or after sending the sixth indication message. Optionally, the sixth indication message can be signaling for data transmission scheduling, meaning that after receiving signaling for data transmission scheduling, the terminal device in the second mode can switch from the second mode to the first mode to perform data transmission.

[0145] In one possible implementation, the terminal device can switch between a first mode and a second mode based on a timer. Specifically, after entering the first state, the terminal device can initially default to the second mode for energy saving. When the terminal device in the second mode receives signaling for data transmission scheduling, it starts a timer. During the timer's operation, the terminal device remains in the first mode. When the timer expires, the terminal device switches from the first mode to the second mode. Correspondingly, after the terminal device enters the first state, the network device first sets the terminal device to the second mode. When the network device sends signaling for data transmission scheduling to the terminal device, it can set the terminal device to the first mode and start a timer (the timer's duration is equal to the timer's duration on the terminal device side). When the timer expires, the terminal device switches to the second mode.

[0146] Optionally, when the terminal is in the first mode, the timer can be restarted whenever a scheduling signaling is received.

[0147] Optionally, after the timer expires, the security key used for subsequent data transmission can be re-derived based on the NCC.

[0148] Optionally, the aforementioned timer can be a time alignment timer (TAT). When the TAT timer expires, the terminal device and network device can release or suspend the fourth context information, or they can retain the fourth context information.

[0149] In some embodiments of this application, the terminal device in the first state may support features such as carrier aggregation (CA). Optionally, the carriers supported for aggregation by the terminal device in the first state may be a subset of the carriers supported for aggregation in the RRC connection state; that is, the number of carriers supported for aggregation by the terminal device in the first state is less than the number of carriers supported for aggregation in the RRC connection state.

[0150] In one possible implementation, the RRC state of the terminal device may include: RRC connected state, RRC idle state, and a first state; that is, the first state can replace the existing RRC inactive state. In another possible implementation, the RRC state of the terminal device may include: RRC connected state, RRC idle state, RRC inactive state, and the first state; that is, the first state is introduced into the existing three states in NR. The terminal device can transition between different RRC states. Figure 5 illustrates a schematic diagram of a terminal device transitioning between different RRC states, using RRC connected state, RRC idle state, and the first state as examples. Figure 6 illustrates another schematic diagram of a terminal device transitioning between different RRC states, using RRC connected state, RRC idle state, RRC inactive state, and the first state as examples.

[0151] As shown in Figures 5 and 6, a terminal device in RRC connected state can release or suspend part of its RRC connected state context information and stop measuring periodic reference signals while maintaining its RRC connection with the network device, thus entering the first state. Optionally, in the first state, the terminal device can also save the aforementioned third context information. Optionally, in the first state, the terminal device can start measuring aperiodic reference signals. The terminal device in the first state restores its RRC connected state context information and resumes measuring periodic reference signals, thus entering the RRC connected state. Optionally, in the RRC connected state, the terminal device can stop measuring aperiodic reference signals. After releasing the RRC connection in the first state, the terminal device can enter the RRC idle state. For a terminal device in the RRC idle state, neither the terminal device nor the network device saves the terminal device's context information.

[0152] In the first state, the terminal device retains the context information of the RRC inactive state. After enabling the measurement of the periodic reference signal, it can enter the RRC inactive state. Alternatively, in the first state, the terminal device can release or suspend some context information (such as security configuration information, third context information, etc.) and enable the measurement of the periodic reference signal before entering the RRC inactive state.

[0153] In the RRC inactive state, the terminal device retains the context information of the RRC inactive state. After stopping the measurement of the periodic reference signal or performing periodic reference signal measurement with a longer period, it can enter the first state. Alternatively, the terminal device in the RRC inactive state can add some context information (such as security configuration information, third context information, etc.) or restore the suspended context information, and after stopping the measurement of the periodic reference signal or performing periodic reference signal measurement with a longer period, it can enter the first state.

[0154] Optionally, in the first state, unlike in the RRC inactive state, the terminal device sends a notification message to the network device whenever a cell change occurs, to inform the network device of the cell change. In other words, a terminal device in the RRC inactive state can enter the first state after enabling this function; conversely, a terminal device in the first state that disables this function enters the RRC inactive state. The terminal device can measure the periodic reference signal in both the RRC inactive state and the first state. The measurement periods can be the same or different, or the terminal device can stop measuring the periodic reference signal in the first state.

[0155] The transitions between the RRC connected state and the RRC idle state, the transitions between the RRC connected state and the RRC inactive state, and the transitions from the RRC inactive state to the RRC idle state can be found in Figure 4 and related descriptions.

[0156] Other characteristics of the terminal device in the first state can be found in the description above.

[0157] In this embodiment of the application, the terminal device can switch between different RRC states based on the instructions of the network device.

[0158] It should be understood that in this application, "transition", "switch", "enter", "release", and "change" are all used to describe changes in RRC state and can be used interchangeably. For example, the transition from RRC connected state to RRC inactive state can be expressed as "transition from RRC_CONNECTED to RRC_INACTIVE".

[0159] It should be understood that in this application, "stop", "suspend", "pause", "cancel" or "cancel" can be used interchangeably. For example, "stop the measurement of the reference signal of the period" can also be expressed as "cancel the measurement of the reference signal of the period".

[0160] In this embodiment of the application, when the terminal device has an uplink data transmission requirement in the first state, it sends a first signaling to the network device. The first signaling triggers the network device to schedule the uplink data transmission of the terminal device, so that the terminal device can send uplink data based on the scheduling of the network device.

[0161] Based on the system architecture shown in Figures 1, 2, or 3 above, Figure 7 illustrates a schematic diagram of an uplink data transmission process. In the embodiments of this application, the functions of the network device can also be executed by modules (such as chips) within the network device, or by a control subsystem containing network device functions. This control subsystem containing network device functions can be a control center in the aforementioned application scenarios such as smart grids, industrial control, intelligent transportation, and smart cities. The functions of the terminal device can also be executed by modules (such as chips or modems) within the terminal device, or by a device containing terminal device functions.

[0162] As shown in Figure 7, the process may include the following steps:

[0163] Step 701: The terminal device in the first state sends the first signaling to the network device.

[0164] This network device belongs to the network device of the serving cell where the terminal device is currently located.

[0165] The first signaling is used to trigger the scheduling of uplink data transmission to the terminal device. In one possible implementation, the first signaling is a Layer 1 signaling or a Layer 2 signaling, such as a preamble, a scheduling request (SR), or a first sequence. When the first signaling is a preamble, an example of the uplink data transmission process can be shown in Figure 8; when the first signaling is a scheduling request, an example of the uplink data transmission process can be shown in Figure 9.

[0166] Optionally, a terminal device in the first state may send a first signaling message to the network device when it needs to send uplink data.

[0167] Based on the system architecture shown in Figure 2, in step 701, the terminal device sends the first signaling to the DU.

[0168] Based on the system architecture shown in Figure 3, in step 701, the terminal device sends the first signaling to the O-DU.

[0169] Step 702: After receiving the first signaling, the network device sends the third signaling to the terminal device.

[0170] This third signaling is used to schedule uplink data transmission for the terminal device.

[0171] Optionally, the third signaling can be either Layer 1 signaling or Layer 2 signaling.

[0172] Optionally, third signaling can indicate the uplink resources used by the terminal device.

[0173] In the system architecture shown in Figure 2, in step 702, the DU sends a third signaling message to the terminal device. Optionally, the DU can implement scheduling based on C-RNTI. Specifically, the resource information used by the network device for scheduling the terminal device can be obtained through RIC.

[0174] Based on the system architecture shown in Figure 3, in step 702, the O-DU sends a third signaling message to the terminal device. Optionally, the O-DU can implement scheduling based on the C-RNTI method. Specifically, the resource information used by the network device for scheduling the terminal device can be obtained through RIC.

[0175] Step 704: After receiving the third signaling, the terminal device sends uplink data to the network device.

[0176] Optionally, the terminal device may send uplink data to the network device based on the uplink resources indicated by the network device.

[0177] In step 704, the terminal device can send uplink data based on the context information.

[0178] For example, in step 704, the terminal device encrypts the uplink data using the encryption key from the security key included in the context information, and performs integrity protection on the uplink data using the integrity protection key included in the security key. The network device decrypts the received uplink data using the decryption key from the security key included in the context information, and performs integrity protection verification on the received uplink data using the integrity protection key included in the security key, etc.

[0179] For example, in step 704, the terminal device determines the sequence number of the uplink data packet to be sent based on the sequence number of the data packet contained in the context information; on the network device side, the reception status can be fed back to the terminal device based on the sequence number of the uplink data packet.

[0180] In the system architecture shown in Figure 2, in step 704, the DU receives the uplink data and sends it to the CU.

[0181] In the system architecture shown in Figure 3, in step 704, the O-DU receives the uplink data and sends it to the O-CU.

[0182] In step 704, the terminal device and the network device can respectively implement the security of uplink data transmission based on the security configuration information in their stored context information. For example, the security key used for data transmission can be deduced based on the security configuration information. The security key may include a key for integrity protection and / or an encryption key. Specifically, it may include one or more of the following: data plane integrity key K_{UP,int}, data plane encryption key K_{UP,enc}, control plane encryption key K_{CP,enc}, and control plane integrity protection key.

[0183] In the process shown in Figure 7 above, since the terminal device stops measuring the periodic reference signal in the first state, its power consumption can be reduced compared to the RRC connected state, thus achieving energy saving. Furthermore, since the terminal device's context information stored in the first state includes security configuration information, data transmission security can be quickly achieved based on this security configuration information. Compared to the terminal in the RRC inactive state, which requires paging by the network device and the RRC connection recovery process to obtain security configuration information, the above implementation method of this application can improve the speed of transitioning from no data transmission to data transmission.

[0184] In one possible implementation, when the terminal device is in the first state and there is no uplink data transmission requirement or a large uplink data transmission requirement, the terminal device and the network device do not need to save some context information of the terminal device. When there is an uplink data transmission requirement or a large uplink data transmission requirement, this context information can be retrieved again. Specifically, refer to steps 703a and 703b, as well as steps 705a and 705b in Figure 7. For ease of description, this context information is referred to here as the fifth context information.

[0185] Optionally, the fifth context may be a subset of the context information maintained by the terminal in the connected state. In cases where there is no significant data transmission, the fifth context information may not be mandatory. The fifth context information may include context information related to the terminal device's network connection and / or context information related to data transmission performance.

[0186] In one possible implementation, the fifth context information may include one or more of the following:

[0187] - Periodic reference signal configuration information and / or measurement reporting configuration information, etc.;

[0188] -Air interface context information related to data transmission, such as one or more of the following: packet sequence number, data transmission related variables;

[0189] - Security keys, such as keys for integrity protection and / or encryption keys, specifically may include at least one of the following: data plane integrity key K_{UP,int}, data plane encryption key K_{UP,enc}, control plane encryption key K_{CP,enc}, and control plane integrity protection key.

[0190] In one possible implementation, the terminal device deletes or suspends the fifth context information when the first condition is met, and the network device deletes or suspends the fifth context information when the second condition is met.

[0191] Optionally, the terminal device or network device may delete or suspend the fifth context information in the following ways:

[0192] Implementation method A1:

[0193] In step 705a, after completing uplink data transmission, the terminal device deletes or suspends the fifth context information. In step 705b, after determining that uplink data transmission is complete, the network device deletes or suspends the fifth context information of the terminal device. Optionally, the network device can determine whether the terminal device has completed uplink data transmission based on the buffer status reporting (BSR) reported by the terminal device. This application does not limit the implementation method of the network device determining whether uplink data transmission is complete.

[0194] Implementation method A2:

[0195] In step 705a, when the first timer expires, the fifth context information is deleted or suspended. The first timer is started or restarted by the terminal device after receiving the third signaling. In step 705b, when the second timer expires, the network device deletes or suspends the fifth context information. The second timer is started or restarted by the network device when or after sending the third signaling. The duration of the second timer is equal to the duration of the first timer.

[0196] In one possible implementation, the network device can instruct the terminal device to start a first timer at a first moment via a third signaling, and the network device also starts a second timer at the same first moment to ensure the synchronization of the first and second timers.

[0197] In another implementation, after sending the third signaling, the network device can start a second timer at the first moment after the first duration starting from the time of sending the third signaling, according to a pre-set or network-configured duration. The terminal device can start the first timer at that first moment after receiving the third signaling, according to a pre-set or network-configured duration.

[0198] In another possible implementation, the terminal device starts a first timer when it sends the first data packet of uplink data, and the network device starts a second timer when it receives the data packet of the terminal device based on the current schedule.

[0199] Implementation method A3:

[0200] In step 705a, the terminal device deletes or suspends the fifth context information after receiving the fourth signaling. The fourth signaling is sent after the third signaling. In step 705b, the network device deletes or suspends the fifth context information when sending the fourth signaling.

[0201] Optionally, when the network device determines that the uplink data transmission of the terminal device is complete, or when the conditions for ending the uplink transmission are met (such as reaching the maximum duration of the uplink transmission), it can instruct the terminal device to delete or suspend the fifth context information through the fourth signaling, so that the terminal device stops the uplink transmission.

[0202] Implementation method A4:

[0203] In this implementation, the terminal device can determine whether to delete or suspend the fifth context information based on the measurement results of the downlink signal (e.g., the downlink reference signal).

[0204] For example, in step 705a, the terminal device measures the downlink signal (e.g., downlink reference signal) to obtain channel state information. If the channel state information indicates poor channel quality, such as the terminal device possibly being located at a cell edge causing poor channel quality, the terminal device deletes or suspends the fifth context information and notifies the network device to delete or suspend the fifth context information in the terminal device's context information. In step 705b, the network device can delete or suspend the fifth context information of the terminal device after receiving this notification.

[0205] For example, in step 705b, the network device measures the uplink signal (e.g., uplink reference signal) sent by the terminal device to obtain channel state information. If the channel state information indicates poor channel quality, such as the terminal device possibly being located at the cell edge causing poor channel quality, the network device deletes or suspends the fifth context information in the terminal's context information and notifies the terminal device to delete or suspend the fifth context information in its context information. In step 705a, the terminal device can delete or suspend its fifth context information after receiving this notification.

[0206] In this embodiment of the application, the terminal device and the network device can also re-obtain the fifth context information under certain conditions.

[0207] Optionally, the triggering conditions for terminal devices and network devices to obtain the fifth context information may include the following:

[0208] Triggering method 1-1:

[0209] Based on the uplink data transmission requirements, terminal devices and network devices can obtain fifth context information.

[0210] For example, the terminal device obtains the fifth context information before, after, or while sending the first signaling to the network device. Correspondingly, the network device obtains the fifth context information when it receives the first signaling from the terminal device or after receiving the first signaling.

[0211] Triggering methods 1-2:

[0212] Based on the transmission scheduling of uplink data, terminal devices and network devices can obtain fifth context information.

[0213] For example, a network device obtains fifth context information before, after, or while sending third signaling to a terminal device. Correspondingly, a terminal device obtains fifth context information after receiving third signaling from the network device.

[0214] Triggering methods 1-3:

[0215] Based on the timer, the terminal device and network device obtain the fifth context information.

[0216] For example, on the terminal device side, when the first timer starts or restarts, the terminal device obtains the fifth context configuration information. On the network device side, when the second timer starts or restarts, the network device obtains the fifth context configuration information of the terminal device.

[0217] Triggering methods 1-4:

[0218] Based on the measurement results of the signal, the terminal device and network device obtain the fifth context information.

[0219] For example, a terminal device measures a downlink signal (e.g., a downlink reference signal) to obtain channel state information. If the channel state information indicates good channel quality, the terminal device can obtain fifth context information and notify the network device to obtain its own fifth context information. Upon receiving this notification, the network device can then obtain the terminal device's fifth context information.

[0220] For example, a network device measures the uplink signal (e.g., uplink reference signal) sent by a terminal device to obtain channel state information. If the channel state information indicates good channel quality, the network device obtains the fifth context information of the terminal device and notifies the terminal device that it has obtained the fifth context information. The terminal device can obtain the fifth context information after receiving this notification.

[0221] In this application embodiment, the terminal device and network device may obtain the fifth context information in the following ways:

[0222] Implementation method B1:

[0223] If the fifth context information is suspended, the terminal device and network device can restore the suspended fifth context information when the above conditions are met.

[0224] Implementation method B2:

[0225] If the fifth context information is deleted or suspended, the terminal device can obtain the fifth context information based on the information sent by the network side.

[0226] For example, taking the fifth context information as including measurement configuration information and measurement reporting configuration information, the network device can send the measurement configuration information and reporting configuration information used by the terminal device in the first state to the terminal device when the above conditions are met (e.g., when uplink data transmission is completed). This measurement configuration information and reporting configuration information can be set by the network device or pre-agreed upon.

[0227] For example, network devices can include measurement configuration information and measurement reporting configuration information in system messages. When a terminal device receives this system message, it can cache the measurement configuration information and measurement reporting configuration information contained therein. When the above conditions are met (e.g., after receiving a third signaling), the terminal device stores the cached measurement configuration information and measurement reporting configuration information as context information.

[0228] Implementation method B3:

[0229] If the fifth context information is deleted or suspended, the terminal device and network device can deduce the fifth context information using the security configuration information (such as NCC) in the terminal device's context information.

[0230] For example, if the fifth context information includes a security key, the terminal device and the network device can deduce the security key using the NCC in the context information of the terminal device.

[0231] In the above implementation, when certain conditions are met (such as after uplink data transmission is completed), deleting or suspending the fifth context information can reduce some interaction operations or processing behaviors between the network devices related to this context information, thereby achieving energy saving. When there is a need for uplink data transmission, the air interface context information related to data transmission can be obtained quickly to ensure the realization of uplink data transmission. In this way, the goal of low power consumption during data transmission and fast data transmission conversion during data transmission can be achieved.

[0232] Refer to Figure 8, which is an example of the process shown in Figure 7. This uplink data transmission process can reuse the random access process, as shown in Figure 8. This process may include the following steps:

[0233] Step 801: The terminal device sends a preamble to the network device, that is, it sends Msg1.

[0234] Optionally, a preamble can be sent when the terminal device has an uplink data transmission requirement.

[0235] Step 802: After receiving the preamble sent by the terminal device, the network device sends downlink control information (DCI) to the terminal device. The DCI is used to schedule the uplink data transmission of the terminal device.

[0236] Step 803: The network device sends a random access response (RAR) to the terminal device, which is also called sending Msg2.

[0237] The RAR includes a temporary identifier assigned to the terminal device, such as C-RNTI.

[0238] Optionally, RAR can be used to indicate uplink resources, which the terminal device can use to send uplink data.

[0239] Steps 804a and 804b: The terminal device and the network device respectively obtain the fifth context information.

[0240] The specific implementation method for this step can be found in the relevant description in the process shown in Figure 7.

[0241] Step 805: The terminal device sends Msg3 to the network device.

[0242] Optionally, Msg3 may include a temporary identifier for the terminal device, such as C-RNTI.

[0243] Optionally, Msg3 may include uplink data sent by the terminal device.

[0244] Optionally, Msg3 includes a BSR, which indicates the amount of uplink data buffered and awaiting transmission on the terminal device side. The network device can estimate the end time of uplink data transmission for the terminal device based on the BSR sent by the terminal device.

[0245] Steps 806a and 806b: The terminal device and the network device delete or suspend the fifth context information when certain conditions are met.

[0246] The specific implementation method for this step can be found in the relevant description in the process shown in Figure 7.

[0247] Referring to Figure 9, another example of the process shown in Figure 7 is provided. Based on this process, the terminal device can perform uplink data transmission when accessing the cell, or perform uplink data transmission after accessing the cell when there is an uplink data transmission requirement. As shown in Figure 9, this process may include the following steps:

[0248] Step 901: The terminal device sends a preamble or SR to the network device. The preamble or SR is used to request or trigger the network device to schedule uplink data transmission for the terminal device.

[0249] In this step, after the terminal device sends the preamble or SR, it monitors the DCI sent by the network device.

[0250] Step 902: After receiving the SR sent by the terminal device, the network device sends a DCI to the terminal device. The DCI is used to schedule the uplink data transmission of the terminal device.

[0251] Steps 903a and 903b: The terminal device and the network device respectively obtain the fifth context information.

[0252] The specific implementation method for this step can be found in the relevant description in the process shown in Figure 7.

[0253] Step 904: The terminal device sends uplink data to the network device.

[0254] Optionally, the terminal device can also send a BSR to the network device.

[0255] Steps 905a and 905b: The terminal device and the network device delete or suspend the fifth context information when certain conditions are met.

[0256] The specific implementation method for this step can be found in the relevant description in the process shown in Figure 7.

[0257] Based on the process shown in Figure 9 above, the terminal device can perform uplink data transmission multiple times. Specifically, the resources configured for sending SRs for the terminal device can have an expiration period. Within this expiration period, the terminal device can request the network side to schedule its uplink data transmission by sending an SR. Outside this expiration period (or after the expiration period expires), the terminal device can trigger the network side to schedule its uplink data transmission by sending a preamble to the network device.

[0258] In this embodiment of the application, when the network side has a downlink data transmission requirement in the first state, the terminal device can send a second signaling message to the terminal device to schedule the downlink data transmission, so that the terminal device can receive downlink data based on the scheduling of the network device.

[0259] Based on the system architecture shown in Figures 1, 2, or 3 above, Figure 10 illustrates a schematic diagram of a downlink data transmission process. In the embodiments of this application, the functions of the network device can also be executed by modules (such as chips) within the network device, or by a control subsystem containing network device functions. This control subsystem containing network device functions can be a control center in the aforementioned application scenarios such as smart grids, industrial control, intelligent transportation, and smart cities. The functions of the terminal device can also be executed by modules (such as chips or modems) within the terminal device, or by a device containing terminal device functions.

[0260] As shown in Figure 10, the process may include the following steps:

[0261] Step 1001: The network device sends a second signaling message to the terminal device.

[0262] This network device belongs to the network device of the serving cell where the terminal device is currently located. The terminal device may be in state 1.

[0263] The second signaling is used to schedule downlink data transmission for the terminal device.

[0264] Optionally, the second signaling can be Layer 1 signaling or Layer 2 signaling. For example, the second signaling is DCI.

[0265] Optionally, the second signaling can indicate the downlink resources used by the terminal device.

[0266] Optionally, the network device can send second signaling in all directions, such as sending DCI in all beam directions, to improve the success rate of receiving the second signaling.

[0267] Optionally, a public or private search space can be pre-configured for transmitting the second signaling. Accordingly, the terminal device can periodically monitor this public or private search space to obtain the second signaling.

[0268] Optionally, a second signaling message may be sent to the terminal device when there is a downlink data transmission requirement. For example, when downlink data destined for the terminal device arrives at the network device, or when the network device needs to send downlink data to the terminal.

[0269] Based on the system architecture shown in Figure 2, in step 1001, the DU sends a second signaling message to the terminal device. Optionally, the DU can implement scheduling based on the C-RNTI method. Specifically, the resource information used by the network device for scheduling the terminal device can be obtained through the RIC.

[0270] Based on the system architecture shown in Figure 3, in step 1001, the O-DU sends a second signaling message to the terminal device. Optionally, the O-DU can implement scheduling based on the C-RNTI method. Specifically, the resource information used by the network device for scheduling the terminal device can be obtained through RIC.

[0271] Step 1003: The network device sends downlink data to the terminal device.

[0272] Optionally, the terminal device may receive downlink data based on the downlink resources indicated by the network device.

[0273] In step 1003, the network device can send downlink data based on context information.

[0274] For example, the network device encrypts downlink data using the encryption key from the security key contained in the context information of the terminal device, and performs integrity protection on the downlink data using the integrity protection key included in the security key. The terminal device decrypts the received downlink data using the decryption key from the security key contained in the context information, and performs integrity protection verification on the received downlink data using the integrity protection key included in the security key, etc.

[0275] For example, network devices determine the sequence number of downlink data packets to be sent based on the sequence number of the data packets contained in the context information; on the terminal device side, the reception status can be fed back to the network device based on the sequence number of the downlink data packets.

[0276] Based on the system architecture shown in Figure 2, in step 1003, the DU sends downlink data to the terminal device.

[0277] Based on the system architecture shown in Figure 3, in step 1003, the O-DU sends downlink data to the terminal device.

[0278] In one possible implementation, in step 1003, the terminal device and the network device can respectively implement the security of downlink data transmission based on the security configuration information in their stored context information. For example, the security key used for data transmission can be deduced based on the security configuration information. For example, the security key may include a key for integrity protection and / or an encryption key. Specifically, it may include one or more of the following: a data plane integrity key K_{UP,int}, a data plane encryption key K_{UP,enc}, a control plane encryption key K_{CP,enc}, and a control plane integrity protection key.

[0279] Similarly, network devices can implement downlink data transmission security for a terminal device based on the security configuration information stored in the context information of that terminal device.

[0280] In the process shown in Figure 10 above, since the terminal device stops measuring the periodic reference signal in the first state, its power consumption can be reduced compared to the RRC connected state, thus achieving energy saving. Furthermore, since the terminal device's context information stored in the first state includes security configuration information, data transmission security can be quickly achieved based on this security configuration information. Compared to the terminal in the RRC inactive state, which requires paging by the network device and the RRC connection recovery process to obtain security configuration information, the above implementation method of this application can improve the speed of transitioning from no data transmission to data transmission.

[0281] In one possible implementation, the terminal device can measure the downlink reference signal transmitted along with the path and report the measurement results (e.g., channel state information) to the network device.

[0282] Optionally, the second signaling can be used to instruct the terminal device to measure the accompanying reference signal, or to instruct the network side that there is an accompanying reference signal being transmitted. Accordingly, the terminal device can receive downlink data and the accompanying reference signal according to the second signaling, measure the reference signal to obtain a measurement result (e.g., channel state information), and in step 1004, send the measurement result to the network device so that the network device can select appropriate downlink resources for the terminal based on the measurement result, thereby improving the performance and efficiency of downlink transmission.

[0283] Optionally, the network device may, based on the amount of data packets, instruct the terminal device in the second signaling whether measurement feedback is required, or whether an accompanying reference signal is to be sent, or decide whether to send an accompanying reference signal in the downlink data based on the amount of downlink data.

[0284] In one possible implementation, the terminal device can provide feedback to the network device regarding the reception status of downlink data. Specifically, if the terminal device successfully receives downlink data, it can send a first sequence of a first signal to the network device, indicating that the terminal device has successfully received the downlink data. If the terminal device fails to receive downlink data, it can either not send feedback information to the network device, or send a second sequence of the first signal to the network device, indicating that the terminal device has failed to receive the downlink data.

[0285] Optionally, the first signal can be the aforementioned first signaling, such as a preamble.

[0286] Optionally, the first signal can also be a sounding reference signal (SRS).

[0287] Optionally, the first signal can also be used to assess time advanced (TA), meaning that the network device can determine the TA based on the first signal.

[0288] Optionally, the first signal can also be used to assess the channel state; that is, the network device can obtain network channel state information by measuring the first signal.

[0289] The implementation of the terminal device's feedback on downlink data reception to the network device can also be independent of the downlink data transmission process shown in Figure 10. That is, in one possible implementation, when the terminal device provides uplink feedback on downlink transmission, if it successfully receives downlink data, it sends a first sequence of a first signal to the network device to indicate that the terminal device has successfully received the downlink data. If downlink data reception fails, uplink feedback can be omitted, or a second sequence of the first signal can be sent to the network device to indicate that the terminal device has failed to receive the downlink data.

[0290] Optionally, the first signal is a preamble or a probe reference signal.

[0291] Optionally, before receiving downlink data, the terminal device also receives a second signaling, which is used to schedule downlink data transmission for the terminal device.

[0292] Optionally, the terminal device is in the first state.

[0293] In one possible implementation, the scheduling of downlink transmission and the process of downlink data transmission may be executed multiple times. As shown in Figure 10, steps 1005 to 1006 illustrate the process of scheduling downlink transmission for the terminal device again and sending downlink data to the terminal device.

[0294] For example, when the amount of downlink data is small, downlink data transmission can be completed in a single downlink transmission scheduling and transmission. When the amount of downlink data is large, such as when multiple data packets need to be sent, or when the data packets are large, multiple downlink transmission scheduling and transmissions may be required to complete the transmission of the downlink data.

[0295] For example, after the network device selects a new downlink resource for the terminal based on the measurement results (such as channel state information) reported by the terminal device, or when it obtains the channel state information based on the measurement of the first signal and performs subsequent scheduling, it can indicate the new resource to the terminal device by executing downlink transmission scheduling.

[0296] Optionally, for each downlink transmission scheduling, the terminal device can measure and provide feedback on the downlink accompanying reference signal.

[0297] Optionally, for the first downlink transmission, there may be no downlink accompanying reference signal transmission.

[0298] In one possible implementation, when the terminal device is in the first state, if there is no downlink data transmission requirement or no large downlink data transmission requirement, the terminal device and the network device do not need to save the fifth context information of the terminal device. When there is a downlink data transmission requirement or a large downlink data transmission requirement, the fifth context information can be obtained again. For details, please refer to steps 1002a and 1002b, as well as steps 1008a and 1008b in Figure 10.

[0299] In one possible implementation, the terminal device deletes or suspends the fifth context information when the first condition is met, and the network device deletes or suspends the fifth context information when the second condition is met, in order to reduce power consumption.

[0300] Optionally, the terminal device or network device may delete or suspend the fifth context information in the following ways:

[0301] Implementation method C1:

[0302] In step 1008a, after determining that downlink data transmission is complete, the terminal device deletes or suspends the fifth context information. Optionally, if the terminal device does not receive downlink data within a set time period, it can determine that downlink data transmission is complete. This application does not limit the implementation method of the terminal device determining whether downlink data transmission is complete.

[0303] In step 1008b, after completing downlink data transmission, the network device deletes or suspends the fifth context information of the terminal device.

[0304] Implementation method C2:

[0305] In step 1008a, when the first timer expires, the terminal device deletes or suspends the fifth context information. The first timer is started after the terminal device receives the second signaling.

[0306] In step 1008b, when the second timer expires, the network device deletes or suspends the fifth context information. The second timer is started or restarted by the network device after sending the second signaling. The duration of the second timer is equal to the duration of the first timer.

[0307] In one possible implementation, the network device can instruct the terminal device to start a first timer at a first moment via a second signaling, and the network device also starts a second timer at the same first moment to ensure the synchronization of the first and second timers.

[0308] In another implementation, after sending the second signaling, the network device can start a second timer at the first moment after a first duration starting from the time of sending the second signaling, according to a preset duration or a duration configured by the network side. After receiving the second signaling, the terminal device can start a first timer at the first moment, according to a preset duration or a duration configured by the network side.

[0309] In another possible implementation, the network device starts a second timer when sending the first data packet of downlink data, and the terminal device starts a first timer when it receives the data packet from the network device based on this scheduling.

[0310] Implementation method C3:

[0311] In step 1008a, the terminal device deletes or suspends the fifth context information after receiving the fourth signaling. The fourth signaling is sent after the second signaling, as shown in step 1007 of Figure 10.

[0312] In step 1008b, the network device deletes or suspends the fifth context information when sending the fourth signaling.

[0313] Optionally, when the downlink data transmission of the network device is completed, or when the conditions for ending the downlink transmission are met (such as reaching the maximum duration of downlink transmission), the terminal device can be instructed to delete or suspend the fifth context information through the fourth signaling, so that the terminal device stops receiving downlink data.

[0314] Implementation method C4:

[0315] In this implementation, the terminal device can determine whether to delete or suspend the fifth context information based on the measurement results of the downlink signal (e.g., the downlink reference signal). Alternatively, the network device can determine whether to delete or suspend the fifth context information based on the measurement results of the uplink signal (e.g., the uplink reference signal). For a specific implementation, please refer to implementation A1 above.

[0316] In this embodiment of the application, the terminal device and the network device can also re-obtain the fifth context information under certain conditions.

[0317] Optionally, the triggering conditions for terminal devices and network devices to obtain the fifth context information may include the following:

[0318] Triggering method 2-1:

[0319] Based on the transmission scheduling of uplink data, terminal devices and network devices can obtain fifth context information.

[0320] For example, the network device obtains the fifth context information before, after, or while sending the second signaling to the terminal device. Correspondingly, the terminal device obtains the fifth context information after receiving the second signaling from the network device.

[0321] Triggering method 2-2:

[0322] Based on the timer, the terminal device and network device obtain the fifth context information.

[0323] For example, on the terminal device side, when the first timer starts or restarts, the terminal device obtains the fifth context configuration information. On the network device side, when the second timer starts or restarts, the network device obtains the fifth context configuration information of the terminal device.

[0324] Triggering methods 2-3:

[0325] Based on the signal measurement results, the terminal device and network device obtain the fifth context information. For specific implementation details, please refer to triggering methods 1-4.

[0326] In this application embodiment, the terminal device and network device can obtain the fifth context information in a manner that can refer to the above-mentioned implementation method B1, implementation method B2 or implementation method B3.

[0327] In the above implementation, when certain conditions are met (such as after downlink data transmission is completed), the fifth context information is deleted or suspended. This can reduce some interaction operations or processing behaviors between the network devices related to this context information, thereby achieving energy saving. When there is a need for downlink data transmission, the air interface context information related to data transmission can be obtained quickly to ensure the realization of downlink data transmission. In this way, the goal of low power consumption during data transmission and fast data transmission conversion during data transmission can be achieved.

[0328] In one possible implementation, when the data transmission of the terminal device in the RRC connection state is completed, or when the data transmission scheduling for the terminal device is completed, the terminal device can enter the first state from the RRC connection state to save power consumption.

[0329] In another possible implementation, after the data transmission of the terminal device in the RRC connected state is completed, or after the data transmission scheduling for the terminal device is completed, the terminal device can enter the first state from the RRC connected state after a certain delay to save power consumption. Optionally, this delay can be preset or configured by the network side.

[0330] It is understood that, in order to achieve the functions in the above embodiments, the network device and terminal device include hardware structures and / or software modules corresponding to perform each function. Those skilled in the art should readily recognize that, based on the units and method steps of the various examples described in conjunction with the embodiments disclosed in this application, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0331] Figures 11 and 12 are schematic diagrams of possible communication devices provided in embodiments of this application. These communication devices can be used to implement the functions of terminal devices or network devices in the above method embodiments, and thus can also achieve the beneficial effects of the above method embodiments. In the embodiments of this application, the communication device can be one of the terminal devices 120a-120j shown in Figure 1, or it can be a base station 110a or 110b shown in Figure 1, or it can be a module (such as a chip) applied to a terminal device or base station.

[0332] As shown in Figure 11, the communication device 1100 includes a processing unit 1110 and a transceiver unit 1120. The communication device 1100 is used to implement the functions of the terminal device or network device in the method embodiments shown in Figures 7 to 10 above.

[0333] When the communication device 1100 is used to implement the functions of the terminal device in the method embodiments shown in Figures 7 to 10: In a first state, the processing unit 1110 is used to send a first signaling or receive a second signaling through the transceiver unit 1120. The first signaling is used to trigger the scheduling of uplink data transmission for the terminal device, and the second signaling is used to schedule downlink data transmission for the terminal device. The context information stored by the terminal device in the first state includes a portion of the context information stored by the terminal device in the RRC connection state, and the portion of the context information includes security configuration information.

[0334] When the communication device 1100 is used to implement the functions of the network device in the method embodiments shown in Figures 7 to 10: the transceiver unit 1120 is used to receive a first signaling or send a second signaling, wherein the first signaling is used to trigger the scheduling of uplink data transmission for the terminal device in the first state, and the second signaling is used to schedule downlink data transmission for the terminal device in the first state. The context information stored by the terminal device in the first state includes a portion of the context information stored by the terminal device in the RRC connection state, and the portion of the context information includes security configuration information.

[0335] A more detailed description of the above-mentioned processing unit 1110 and transceiver unit 1120 can be obtained directly from the description in the method embodiment shown in the relevant drawings, and will not be repeated here.

[0336] As shown in Figure 12, the communication device 1200 includes a processor 1210 and an interface circuit 1220. The processor 1210 and the interface circuit 1220 are coupled to each other. It is understood that the interface circuit 1220 can be a transceiver or an input / output interface. Optionally, the communication device 1200 may also include a memory 1230 for storing instructions executed by the processor 1210, or storing input data required by the processor 1210 to execute instructions, or storing data generated after the processor 1210 executes instructions.

[0337] When the communication device 1200 is used to implement the method shown in Figures 7 to 10, the processor 1210 is used to implement the function of the processing unit 1110, and the interface circuit 1220 is used to implement the function of the transceiver unit 1120.

[0338] When the aforementioned communication device is a chip applied to a terminal device, the terminal chip implements the functions of the terminal device in the above method embodiments. The terminal chip receives information from other modules (such as an RF module or antenna) in the terminal device, the information being sent to the terminal device by the network device; or, the terminal chip sends information to other modules (such as an RF module or antenna) in the terminal device, the information being sent to the network device by the terminal device.

[0339] When the aforementioned communication device is a module applied to a network device, the network device module implements the functions of the network device in the above method embodiments. The network device module receives information from other modules (such as radio frequency modules or antennas) within the network device; this information is sent from the terminal device to the network device. Alternatively, the network device module sends information to other modules (such as radio frequency modules or antennas) within the network device; this information is sent from the network device to the terminal device. The network device module here can be the baseband chip of the network device, or a DU (Digital Unit) or other modules. The DU here can be a DU under an Open Radio Access Network (O-RAN) architecture.

[0340] It is understood that the processor in the embodiments of this application may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor may be a microprocessor or any conventional processor.

[0341] This application provides another example of a communication device, which includes at least one processor and at least one memory coupled together. The at least one processor and the at least one memory are used to store instructions. When the instructions are executed by the at least one processor, the communication device performs the methods described in the above embodiments. Taking a communication device including a processor and a memory as an example, as shown in FIG12, communication device 1200 includes a processor 1210 and a memory 1230. The processor 1210 and the memory 1230 are coupled together. The memory 1230 stores instructions. When the instructions stored in the memory 1230 are executed by the processor 1210, the communication device 1200 performs the methods performed by the terminal device or network device described in the above embodiments.

[0342] The method steps in the embodiments of this application can be implemented in hardware or in software instructions executable by a processor. The software instructions can consist of corresponding software modules, which can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. The storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Alternatively, the ASIC can reside in a network device or a terminal device. The processor and storage medium can also exist as discrete components in a network device or a terminal device.

[0343] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of this application are performed entirely or partially. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user equipment, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. 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 integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video optical disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both types of storage media.

[0344] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0345] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates an "or" relationship between the preceding and following related objects; in the formulas of this application, the character " / " indicates a "division" relationship between the preceding and following related objects. "Including at least one of A, B, and C" can mean: including A; including B; including C; including A and B; including A and C; including B and C; including A, B, and C.

[0346] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

Claims

1. A communication method, characterized in that, Applied to terminal devices, including: In the first state, a first signaling is sent or a second signaling is received. The first signaling is used to trigger the scheduling of uplink data transmission for the terminal device, and the second signaling is used to schedule downlink data transmission for the terminal device. In the first state, the context information stored by the terminal device in the first state includes a portion of the context information stored by the terminal device in the RRC connection state, and the portion of the context information includes security configuration information.

2. The method as described in claim 1, characterized in that, In the first state, the terminal device stops measuring the periodic reference signal; or In the first state, the terminal device measures the periodic reference signal, and the length of the measurement period is greater than the length of the measurement period when measuring the periodic reference signal in the RRC connected state or the RRC inactive state; or In the first state, the terminal device measures the periodic reference signal, and the length of the measurement period is equal to the length of the measurement period when measuring the periodic reference signal in the RRC connected state or the RRC inactive state.

3. The method according to any one of claims 1-2, characterized in that, Before or after sending the first signaling, or after receiving the second signaling, or after receiving the third signaling, the method further includes: Obtain the fifth context information; The third signaling is triggered based on the first signaling, and the third signaling is used to schedule uplink data transmission for the terminal device. The fifth context information includes one or more of the following: Air interface context information related to data transmission, including data packet sequence number and / or data transmission related variables, which are used to determine the time window of data transmission; Periodic reference signal configuration information and / or measurement reporting configuration information; Security key.

4. The method as described in claim 3, characterized in that, The process of obtaining the fifth context information includes: Based on the security configuration information in the context configuration information saved by the terminal device in the first state, the security key in the fifth context information is deduced; or Based on the information sent by the network device, obtain the periodic reference signal configuration information and / or measurement reporting configuration information from the fifth context information; or Restore the suspended fifth context information.

5. The method according to any one of claims 3-4, characterized in that, Also includes: The fifth context information is deleted or suspended when the first condition is met.

6. The method as described in claim 5, characterized in that, Deleting or suspending the fifth context information when the first condition is met includes: After completing the uplink data transmission or the downlink data transmission, delete or suspend the fifth context information; or When the first timer expires, the fifth context information is deleted or suspended; wherein the first timer is started after receiving the third signaling, or after receiving the second signaling; or Upon receiving the fourth signaling, the fifth context information is deleted or suspended.

7. The method according to any one of claims 1-6, characterized in that, The second signaling is also used to instruct the terminal device to measure the reference signal transmitted along with the path, or to indicate that there is a reference signal transmitted along with the path.

8. The method according to any one of claims 1-7, characterized in that, After receiving the second signaling in the first state, the terminal device further includes: Receive downlink data; A first sequence of first signals is sent, the first sequence being used to indicate that the terminal device has successfully received the downlink data.

9. The method according to any one of claims 1-8, characterized in that, After receiving the second signaling in the first state, the terminal device further includes: A second sequence of a first signal is sent, the second sequence being used to indicate that the terminal device has failed to receive downlink data.

10. The method as described in claim 8 or 9, characterized in that, The first signal is a preamble or a probe reference signal.

11. A communication method, characterized in that, Applied to network devices, including: Receive a first signaling or send a second signaling, wherein the first signaling is used to trigger the scheduling of uplink data transmission for the terminal device in the first state, and the second signaling is used to schedule downlink data transmission for the terminal device in the first state; The context information stored by the terminal device in the first state includes a portion of the context information stored by the terminal device in the RRC connection state, and the portion of the context information includes security configuration information.

12. The method as described in claim 11, characterized in that, In the first state, the terminal device stops measuring the periodic reference signal; or In the first state, the terminal device measures the periodic reference signal, and the length of the measurement period is greater than the length of the measurement period when measuring the periodic reference signal in the RRC connected state or the RRC inactive state; or In the first state, the terminal device measures the periodic reference signal, and the length of the measurement period is equal to the length of the measurement period when measuring the periodic reference signal in the RRC connected state or the RRC inactive state.

13. The method according to any one of claims 11-12, characterized in that, Before or after sending the first signaling, or after receiving the second signaling, or after receiving the third signaling, the method further includes: Obtain the fifth context information of the terminal device; The third signaling is triggered based on the first signaling, and the third signaling is used to schedule uplink data transmission for the terminal device. The fifth context information includes one or more of the following: Air interface context information related to data transmission, including data packet sequence number and / or data transmission related variables, which are used to determine the time window of data transmission; Periodic reference signal configuration information and / or measurement reporting configuration information; Security key.

14. The method as described in claim 13, characterized in that, The process of obtaining the fifth context information includes: Based on the security configuration information in the context configuration information saved by the terminal device in the first state, the security key in the fifth context information is deduced; or Restore the suspended fifth context information.

15. The method according to any one of claims 13-14, characterized in that, Also includes: The fifth context information is deleted or suspended when the second condition is met.

16. The method as described in claim 15, characterized in that, The step of deleting or suspending the fifth context information when the second condition is met includes: After completing the uplink data transmission or the downlink data transmission, delete or suspend the fifth context information; or When the second timer expires, the fifth context information is deleted or suspended; wherein the second timer is started when the third signaling is sent, or when the second signaling is sent; or When or after sending the fourth signaling, the fifth context information is deleted or suspended, the fourth signaling being used to instruct the terminal device to delete or suspend the fifth context information.

17. The method according to any one of claims 11-16, characterized in that, The second signaling is also used to instruct the terminal device to measure the reference signal transmitted along with the path, or to indicate that there is a reference signal transmitted along with the path.

18. The method according to any one of claims 11-17, characterized in that, After sending the second signaling, the process also includes: Send downlink data; A first sequence of receiving a first signal, the first sequence being used to indicate that the terminal device has successfully received the downlink data.

19. The method according to any one of claims 11-18, characterized in that, After sending the second signaling, the process also includes: Send downlink data; A second sequence is received from the first signal, the second sequence being used to indicate that the terminal device has failed to receive the downlink data.

20. The method as described in claim 18 or 19, characterized in that, The first signal is a preamble or a probe reference signal.

21. The method according to any one of claims 11-20, characterized in that, Also includes: After the terminal device in the first state accesses the serving cell, a first message is sent to the candidate target cell of the terminal device; Receive a second message sent by the candidate target cell according to the first message, wherein the second message includes the temporary identifier of the terminal device in the candidate target cell, and / or the security configuration information of the terminal device in the candidate target cell; Send the temporary identifier and / or the security configuration information to the terminal device.

22. The method as described in claim 21, characterized in that, The second message also includes the validity period of the temporary identifier and / or the activation time of the security configuration information.

23. The method according to any one of claims 11-22, characterized in that, Also includes: When the terminal device switches from the source cell to the target cell, the context information of the terminal device is sent to the target cell.

24. The method according to any one of claims 1-23, characterized in that, The security configuration information includes one or more of the following: next-hop chain calculation, security key.

25. The method according to any one of claims 1-24, characterized in that, The context information saved by the terminal device in the first state also includes first context information and / or second context information; The first context information includes a data packet sequence number and / or data transmission related variables, wherein the data transmission related variables are used to determine the time window for data transmission; The second context information includes one or more of the following: air interface key, header compression status, compression-related context, uplink data compression status, QoS and data radio bearer mapping relationship, application layer measurement configuration information, temporary terminal device identifier used by the terminal device in the source cell, physical cell identifier of the source cell, and globally unique cell identifier of the source cell.

26. The method according to any one of claims 1-25, characterized in that, The context information saved by the terminal device in the first state also includes third context information, which includes one or more of the following: The temporary identifier of the terminal device in the candidate target cell; or The terminal device's security configuration information in the candidate target cell.

27. A communication device, characterized in that, It includes units or modules for performing the method as described in any one of claims 1-10, 24-26, or includes units or modules for performing the method as described in any one of claims 11-26.

28. A communication device, characterized in that, include: One or more processors are configured to perform the method as claimed in any one of claims 1-10, 24-26, or to perform the method as claimed in any one of claims 11-26.

29. A readable storage medium, characterized in that, The readable storage medium stores a program or instructions that, when executed on the device, cause the device to perform the method as claimed in any one of claims 1-10, 24-26, or the method as claimed in any one of claims 11-26.

30. A chip system, characterized in that, Includes a processor for supporting a computer device in implementing the method as described in any one of claims 1-10, 24-26, or in implementing the method as described in any one of claims 11-26.

31. A computer program product, characterized in that, The computer program product includes a program; when the computer program is run on a computer, it causes the computer to perform the method as described in any one of claims 1-10, 24-26, or to perform the method as described in any one of claims 11-26.

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