Communication method and apparatus

Abstract

A communication method and apparatus, relating to the technical field of wireless communications. The method comprises: a terminal device receives first indication information, wherein the first indication information indicates that the terminal device changes from a radio resource control (RRC) connected state to a first state; and entering the first state on the basis of the first indication information, wherein context information stored by the terminal device in the first state includes part of context information among context information stored by the terminal device in the RRC connected state, and the part of context information includes 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. 202411562437.4, 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, the method being applied to a terminal device, the method comprising: receiving first indication information, the first indication information indicating that the terminal device changes from a radio resource control (RRC) connected state to a first state; entering the first state according to the first indication information, 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 connected state, the portion of the context information including 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. For example, a security key for data transmission can be derived from the 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 indication information is carried in an RRC connection release message or downlink control information (DCI).

[0014] 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.

[0015] In the above implementation, since the terminal device can stop measuring the periodic reference signal in the first state, or use a longer measurement period for measurement, the power consumption of the terminal device can be reduced and energy saving can be achieved compared with the RRC connected state or the RRC inactive state.

[0016] In one possible implementation, after receiving the first indication information, the method further includes: releasing or suspending one or more of the following context information of the terminal device in the RRC connection state: air interface context information related to data transmission, and periodic measurement configuration information.

[0017] 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.

[0018] In one possible implementation, before receiving the first indication information, the method further includes: sending a first request, wherein the first request is used to request entering the first state.

[0019] In one possible implementation, sending the first request includes: determining, based on the quality and / or service information of the serving cell, a change from the RRC connected state to the first state, and sending the first request; or, determining, based on measurements of downlink signals, a change from the RRC connected state to the first state, and sending the first request; or, determining, based on measurements of downlink signals and statistics of transmitted data volume, a change from the RRC connected state to the first state, and sending the first request.

[0020] In one possible implementation, the business information includes one or more of the following: business data volume, the trend of business data volume change, the duration of the business, and the business type.

[0021] In one possible implementation, the terminal device, in the first state, further includes: receiving second indication information, the second indication information being used to instruct the terminal device to change from the first state to an RRC connection state; entering the RRC connection state according to the second indication information, the terminal device recovering the context information of the RRC connection state and recovering the measurement of the reference signal for the period under the RRC connection.

[0022] One possible implementation also includes sending a second request, which is used to request entry into the RRC connection state.

[0023] In one possible implementation, sending the second request includes: determining, based on the quality and / or service information of the serving cell, a change from the first state to the RRC connected state, and sending the second request; or, determining, based on measurements of downlink signals, a change from the first state to the RRC connected state, and sending the second request; or, determining, based on measurements of downlink signals and statistics of transmitted data volume, a change from the first state to the RRC connected state, and sending the second request.

[0024] In one possible implementation, when the terminal device is in the first state, it further includes: receiving third indication information, the third indication information being used to instruct the terminal device to change from the first state to the RRC inactive state; and entering the RRC inactive state according to the third indication information.

[0025] In one possible implementation, when the terminal device is in the RRC inactive state, it further includes: receiving fourth indication information, the fourth indication information being used to instruct the terminal device to change from the RRC inactive state to the first state; and entering the first state according to the fourth indication information.

[0026] In one possible implementation, when the terminal device is in the first state, it further includes: receiving downlink data and a reference signal transmitted along with the downlink data; measuring the reference signal to obtain a measurement result; and transmitting the measurement result. This implementation can improve data transmission efficiency.

[0027] In one possible implementation, the first state includes a first mode and / or a second mode, wherein the terminal device performs data transmission in the first mode and does not transmit data in the second mode.

[0028] In one possible implementation, when the terminal device is in the first mode, it further includes: performing data transmission; receiving fifth indication information, and changing from the first mode to the second mode according to the fifth indication information, wherein the fifth indication information is used to indicate that the terminal device changes from the first mode to the second mode, or to indicate that data transmission is complete.

[0029] In one possible implementation, when the terminal device is in the second mode, it further includes: receiving sixth indication information; and changing from the second mode to the first mode according to the sixth indication information.

[0030] One possible implementation further includes: starting a timer after receiving signaling for data transmission scheduling; during the operation of the timer, the terminal device is in the first mode; when the timer expires, it changes from the first mode to the second mode.

[0031] In one possible implementation, the fourth context information is released or suspended in the second mode and restored in the first mode; and / or, the first search space configuration information is applied in the first mode and the second search space configuration information is applied in the second mode; wherein the search period length indicated by the first search space configuration information is less than the search period length indicated by the second search space configuration information.

[0032] In one possible implementation, the fourth context information includes one or more of the following: a security key, a data packet sequence number, and data transmission related variables, wherein the data transmission related variables are used to determine the time window for data transmission.

[0033] In one possible implementation, when the terminal device is in the first state, it further includes: switching or changing from a source cell to a target cell, wherein the source cell and the target cell belong to the same area; sending an access request or update indication to the target cell, wherein the access request and the update indication are used to trigger the target cell to send a UE change cell indication to the source cell, and the UE change cell indication is used to trigger the source cell to send the saved context information of the terminal device to the target cell.

[0034] In the above implementation, when the terminal device moves between different cells within the same area (e.g., the same tracking area), the context information of the terminal device can migrate to the target cell along with the movement of the terminal device, thereby enabling the terminal device to quickly switch to a state where data transmission can be performed in the target cell.

[0035] In one possible implementation, the security configuration information includes one or more of the following: next-hop chain calculation, security key.

[0036] 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.

[0037] 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.

[0038] In one possible implementation, the third context information may further include one or more of the following: the validity period of the temporary identifier; or the activation time of the security configuration information.

[0039] Secondly, a communication method is provided, which is applied to a network device. The method includes: sending first indication information, the first indication information indicating that the terminal device changes from an RRC connected state to 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 connected state, the portion of the context information including security configuration information; and releasing or suspending the portion of the context information stored by the network device in the RRC connected state.

[0040] 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.

[0041] In one possible implementation, releasing or suspending a portion of the context information of the terminal device in the RRC connection state stored by the network device includes: releasing or suspending one or more of the following in the context information of the terminal device in the RRC connection state stored by the network device: air interface context information related to data transmission, and periodic measurement configuration information.

[0042] In one possible implementation, before sending the first indication information, the method further includes: receiving a first request, the first request being used to request entering the first state; sending the first indication information includes: sending the first indication information according to the first request.

[0043] In one possible implementation, the terminal device, in the first state, further includes: sending second indication information, the second indication information being used to instruct the terminal device to change from the first state to the RRC connection state; and restoring the context information of the terminal device in the RRC connection state saved by the network device.

[0044] In one possible implementation, when the terminal device is in the first state, it further includes: sending third indication information, the third indication information being used to instruct the terminal device to change from the first state to the RRC inactive state.

[0045] In one possible implementation, when the terminal device is in the RRC inactive state, it further includes: sending fourth indication information, the fourth indication information being used to instruct the terminal device to change from the RRC inactive state to the first state.

[0046] In one possible implementation, the first state includes a first mode and / or a second mode, wherein the terminal device performs data transmission in the first mode and does not transmit data in the second mode.

[0047] In one possible implementation, when the terminal device is in the first mode, it further includes: performing data transmission; sending fifth indication information, the fifth indication information being used to indicate that the terminal device changes from the first mode to the second mode, or to indicate that data transmission is complete.

[0048] In one possible implementation, when the terminal device is in the second mode, it further includes: sending a sixth indication message, the sixth indication message being used to instruct the terminal device to change from the second mode to the first mode.

[0049] One possible implementation further includes: sending signaling for data transmission scheduling, starting a timer, setting the terminal device to a first mode during the timer's operation, and changing the terminal device from the first mode to the second mode when the timer expires.

[0050] One possible implementation further includes: starting a timer after receiving signaling for data transmission scheduling; during the operation of the timer, the terminal device is in the first mode; when the timer expires, it changes from the first mode to the second mode.

[0051] In one possible implementation, the fourth context information is released or suspended in the second mode and restored in the first mode; and / or, the first search space configuration information is applied in the first mode and the second search space configuration information is applied in the second mode; wherein the search period length indicated by the first search space configuration information is less than the search period length indicated by the second search space configuration information.

[0052] In one possible implementation, when the terminal device is in the first state, it further includes: receiving a UE cell change instruction from a target cell, the UE cell change instruction being used to instruct the terminal device to switch from a source cell to the target cell, the source cell and the target cell belonging to the same area; sending the context information of the terminal device to the target cell according to the UE cell change instruction; or sending a handover request to the terminal device, the handover request being used to instruct the terminal device to switch from the source cell to the target cell, and sending the context information of the terminal device stored by the network device to the target cell.

[0053] In one possible implementation, the security configuration information includes one or more of the following: next-hop chain calculation, security key.

[0054] In one possible implementation, the context information stored by the network device in the first state of the terminal device 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 of 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.

[0055] In one possible implementation, the context information stored by the network device in the first state of the terminal device 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.

[0056] In one possible implementation, the third context information may further include one or more of the following: the validity period of the temporary identifier; or the activation time of the security configuration information.

[0057] Thirdly, a communication method is provided, applied to a terminal device. The method includes: the terminal device, in a first state, receiving second indication information, the second indication information indicating that the terminal device changes from the first state to an RRC connection state; entering the RRC connection state according to the second indication information, the terminal device recovers the context information of the RRC connection state and resumes the measurement of a periodic reference signal under the RRC connection. Specifically, in the first state, the terminal device stops measuring the periodic reference signal, and 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, the portion of the context information including security configuration information.

[0058] Fourthly, a communication method is provided, applied to a network device. The method includes: a terminal device, in a first state, sending second indication information, the second indication information indicating that the terminal device changes from the first state to an RRC connection state; and restoring the context information of the terminal device in the RRC connection state stored by the network device. In the first state, the terminal device stops measuring a periodic reference signal, and 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, the portion of context information including security configuration information.

[0059] Fifthly, a communication method is provided, applied to a terminal device. The method includes: the terminal device, in a first state, receiving third indication information, the third indication information indicating that the terminal device changes from the first state to an RRC inactive state; and entering the RRC inactive state according to the third indication information. In the first state, the terminal device stops measuring a periodic reference signal, and 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 connected state, the portion of the context information including security configuration information.

[0060] Sixthly, a communication method is provided, applied to a network device. The method includes: a terminal device, in a first state, sending third indication information, the third indication information indicating that the terminal device changes from the first state to an RRC inactive state. In the first state, the terminal device stops measuring a periodic reference signal, and 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 connected state, the portion of the context information including security configuration information.

[0061] A seventh aspect provides a communication method applied to a terminal device. The method includes: when the terminal device is in an RRC inactive state, receiving fourth indication information, the fourth indication information indicating that the terminal device changes from the RRC inactive state to a first state; and entering the first state according to the fourth indication information. In the first state, the terminal device stops measuring a periodic reference signal, and 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 connected state, the portion of the context information including security configuration information.

[0062] Eighthly, a communication method is provided, applied to a network device. The method includes: when a terminal device is in an RRC inactive state, sending fourth indication information, the fourth indication information indicating that the terminal device changes from the RRC inactive state to a first state. In the first state, the terminal device stops measuring a periodic reference signal, and 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 connected state, the portion of the context information including security configuration information.

[0063] A ninth aspect provides a communication apparatus comprising a unit or module for performing the method described in any one of the first to eighth aspects.

[0064] A tenth aspect provides a communication apparatus comprising: one or more processors configured to perform the method described in any one of the first to eighth aspects.

[0065] Eleventh aspect, a readable storage medium is provided, the readable storage medium storing a program or instructions that, when executed on a device, cause the device to perform the method of any one of the first to eighth aspects.

[0066] In a twelfth aspect, a chip system is provided, including a processor for supporting a computer device in implementing the method of any one of the first to eighth aspects.

[0067] In a thirteenth aspect, 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 eighth aspects.

[0068] In a fourteenth aspect, a communication system is provided, comprising 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 second aspects; or, the terminal device performs the method described in any one of the third aspects, and the network device performs the method described in any one of the fourth aspects; or, the terminal device performs the method described in any one of the fifth aspects, and the network device performs the method described in any one of the sixth aspects; or, the terminal device performs the method described in any one of the seventh aspects, and the network device performs the method described in any one of the eighth aspects. Attached Figure Description

[0069] Figure 1 is a schematic diagram of the architecture of the communication system used in the embodiments of this application;

[0070] Figure 2 is a schematic diagram of the RAN node protocol stack in an embodiment of this application;

[0071] Figure 3 is a schematic diagram of the O-RAN structure in an embodiment of this application;

[0072] 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;

[0073] 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;

[0074] 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;

[0075] Figure 7 is a schematic diagram of the process of a terminal device changing from the RRC connected state to the first state in an embodiment of this application;

[0076] Figure 8 is a schematic diagram of the process of another terminal device changing from the RRC connected state to the first state in an embodiment of this application;

[0077] Figure 9 is a schematic diagram of the process of a terminal device changing from a first state to an RRC connected state in an embodiment of this application;

[0078] Figure 10 is a schematic diagram of the process of another terminal device changing from the first state to the RRC connection state in an embodiment of this application;

[0079] Figure 11 is a schematic diagram of the process of a terminal device changing from a first state to an RRC inactive state in an embodiment of this application;

[0080] Figure 12 is a schematic diagram of the process of a terminal device changing from the RRC inactive state to the first state in an embodiment of this application;

[0081] Figure 13 is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0082] Figure 14 is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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, the access network equipment in vehicle-to-everything (V2X) technology can be a roadside unit (RSU).

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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).

[0099] 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).

[0100] 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.

[0101] In some examples, the O-RAN may not contain the O-CU, but only the O-DU.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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, an O-DU is configured to implement higher-level functions in the PHY layer, and an O-RU is configured to implement lower-level functions in the PHY layer or to implement both lower-level functions and radio frequency functions.

[0106] Table 1 shows the correspondence between network elements (or nodes) in the O-RAN system and their achievable protocol layer functions.

[0107] Table 1: Correspondence between O-RAN network elements and their achievable protocol layer functions

[0108] 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).

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] In another possible implementation, the security configuration information includes security keys, such as keys for integrity protection and / or encryption keys.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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}.

[0122] 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).

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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 occupied by the terminal device or other cells that the terminal device may switch to.

[0128] 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 the second message sent by the first network device, obtaining the third context information of the terminal device carried in the second message.

[0129] 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.

[0130] 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).

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] Optionally, the target cell may be one of the candidate target cells, or it may be another cell other than the candidate target cells.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] In this embodiment of the application, 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 the signaling sent by the network side for data transmission scheduling.

[0150] In one possible implementation, the first state includes a first mode and / or a second mode. The first mode supports data transmission or is currently transmitting data; that is, the terminal device can transmit data in the first mode. The second mode does not support data transmission or there is no data transmission at this time; that is, the terminal device cannot transmit data or is not transmitting data in the second mode.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] Optionally, when the terminal is in the first mode, the timer can be restarted whenever a scheduling signaling is received.

[0159] Optionally, after the timer expires, the security key used for subsequent data transmission can be re-derived based on the NCC.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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, if the terminal device in the first state wants to enter the RRC inactive state, it can restore some context information (such as the measurement configuration of the inactive state) and enable the measurement of the periodic reference signal before entering the RRC inactive state.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] Other characteristics of the terminal device in the first state can be found in the description above.

[0169] 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".

[0170] 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".

[0171] Based on the system architecture shown in Figures 1, 2, or 3 above, and the RRC state transition diagram shown in Figure 5 or 6, Figure 7 illustrates a flowchart of a terminal device changing from the RRC connected state to the first state. 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.

[0172] As shown in Figure 7, the process may include the following steps:

[0173] Step 701: The terminal device in RRC connected state sends service information and / or state change tendency information to the network device.

[0174] This network device is the network device belonging to the serving cell of this terminal device.

[0175] This business information may include business information from upstream or downstream operations. This business information, along with status change tendency information, can be used to make decisions regarding RRC status changes.

[0176] Optionally, service information may include one or more of the following: service data volume, the trend of service data volume changes (to reflect the distribution of data volume over time, such as gradually increasing or gradually decreasing), service duration, service type, QoS level, etc. The network device can determine whether to change the terminal device from RRC connected state to the first state based on the service information reported by the terminal device.

[0177] The "service data volume" can be estimated by the terminal device based on the service type. The corresponding service data volume may vary depending on the service type. For example, the service data volume is relatively small for machine type communication (MTC) or ultra-reliable low latency communication (URLLC) services, while it can be relatively large for enhanced mobile broadband (eMBB) or real-time broadband (RTBC) services.

[0178] Optionally, the terminal device can obtain service information based on AT (attention) commands. More specifically, the terminal device can obtain service information based on AT commands when beam alignment is enabled.

[0179] The status change tendency information indicates the terminal device's preferred opinion on the RRC status, or in other words, the status change tendency information can indicate the RRC status recommended or desired by the terminal device. In this process, the RRC status indicated by the status change tendency information is the first status, indicating that the terminal device recommends the first RRC status.

[0180] Optionally, the state change tendency information can be determined by the terminal device based on business information.

[0181] For example, if the service information meets one or more of the following conditions, the terminal device may suggest changing from the RRC connected state to the first state:

[0182] Condition 1: If the total data volume of the services corresponding to the terminal device is less than or equal to the data volume threshold, it indicates that the downlink data transmission volume of the terminal device is relatively low. In this case, to reduce the power consumption of the terminal device, it can be changed from the RRC connected state to the first state. Optionally, the data volume threshold can be preset or configured on the network side.

[0183] Condition 2: If the duration of the service corresponding to the terminal device (i.e., data transmission duration) is less than or equal to the duration threshold, it indicates that the downlink data transmission duration of the terminal device is short. In this case, to reduce the power consumption of the terminal device, it can change from the RRC connected state to the first state. Optionally, this duration threshold can be preset or configured on the network side.

[0184] Condition 3: The data volume of the service corresponding to this terminal device shows a downward trend, indicating that the downlink data transmission volume of this terminal device is gradually decreasing. In this case, in order to reduce the power consumption of the terminal device, it can be changed from the RRC connected state to the first state.

[0185] Condition 4: The service type corresponding to this terminal device is the specified service type, indicating that the downlink data transmission volume of this terminal device is small, the duration is short, or the data transmission efficiency requirement is low. In this case, in order to reduce the power consumption of the terminal device, it can be changed from the RRC connected state to the first state. Optionally, the specified service type can be pre-set or configured on the network side, for example, it can be included in the configuration information of the first state.

[0186] Condition 5: If the QoS level of the service corresponding to the terminal device is lower than or equal to the QoS level threshold, it indicates that the downlink data transmission of the terminal device does not have high requirements for data transmission efficiency. In this case, to reduce the power consumption of the terminal device, it can be changed from the RRC connected state to the first state. Optionally, the QoS level threshold can be preset or configured on the network side.

[0187] It should be understood that the above are merely examples of several conditions that may cause the terminal device to change from the RRC connected state to the first state, and this application does not impose any restrictions on them.

[0188] Optionally, the state change tendency information may include indication information of the RRC state that the terminal device tends to. For example, in this process, the state change tendency information may be indication information of the first state.

[0189] Optionally, the state change tendency information may also include first duration information, which indicates the duration of the RRC state (taking the first state as an example) suggested by the terminal device. The network device can determine the duration for which the terminal device is in the first state based on the first duration information.

[0190] In one possible implementation, after obtaining service information, the terminal device may send the service information and / or state change tendency information to the network device only if certain conditions are met. If these conditions are not met, the terminal device will not send the service information or state change tendency information to the network device. Optionally, these conditions may include one or more of the following:

[0191] Condition a: The data volume of the service corresponding to the terminal device is less than the threshold. Optionally, the threshold may be equal to or different from the aforementioned data volume threshold. This application does not impose any restrictions on this.

[0192] Condition b: The data volume of the service corresponding to this terminal device shows a downward trend;

[0193] Condition c: The duration of the service corresponding to the terminal device is less than or equal to the duration threshold.

[0194] Based on the system architecture shown in Figure 2, in step 701, the terminal device sends service information and / or state change tendency information to the CU (e.g., CU-CP). The CU can determine in subsequent steps whether to change the terminal device from the RRC connected state to the first state based on the service information and / or state change tendency information.

[0195] Based on the system architecture shown in Figure 3, in step 701, the terminal device sends service information and / or state change tendency information to the O-CU (e.g., O-CU-CP). The O-CU can determine in subsequent steps whether to change the terminal device from the RRC connected state to the first state based on the service information and / or state change tendency information.

[0196] Step 701 is an optional step.

[0197] Step 702: The network device determines to change the RRC status of the terminal device from the RRC connected state to the first state.

[0198] In one possible implementation, the network device can determine whether to change the terminal device from the RRC connected state to the first state based on the service information sent by the terminal device. The method by which the network device determines whether to change the terminal device from the RRC connected state to the first state based on the service information can refer to the method in step 701 for the terminal device to determine whether to change from the RRC connected state to the first state.

[0199] In another possible implementation, the network device can determine whether to change the terminal device from the RRC connected state to the RRC state indicated by the state change tendency information sent by the terminal device.

[0200] In another possible implementation, the network device can determine whether to change the terminal device from the RRC connected state to the first state based on the service information corresponding to the terminal device obtained from the core network. The content of this service information can be found in the relevant description of the service information in step 701.

[0201] In another possible implementation, the network device can determine whether to change the terminal device from the RRC connected state to the first state based on the amount of data or the trend of data volume changes of the service data corresponding to the terminal device received from the core network. For example, if the network device determines that the amount of data for the service corresponding to the terminal device is less than or equal to a data volume threshold, it decides to change the terminal device from the RRC state to the first state. As another example, if the network device determines that the trend of data volume changes of the service corresponding to the terminal device is decreasing, it decides to change the terminal device from the RRC connected state to the first state.

[0202] Taking the system architecture shown in Figure 2 as an example, the CU on the RAN side receives downlink data. When the CU sends the data to the DU, it adds indication information to the F1 signaling to indicate that the trend of the buffered data volume is decreasing, or to indicate a change to the first state. After receiving the indication information, the DU sends L1 signaling, L2 signaling, or L3 signaling to the terminal device to indicate that the terminal device changes from the RRC connected state to the first state.

[0203] Taking the system architecture shown in Figure 3 as an example, the O-CU (e.g., O-CU-UP) on the RAN side receives downlink data. When the O-CU sends the data to the O-DU, it adds indication information to the F1 signaling to indicate that the trend of the buffered data volume is decreasing, or to indicate a change to the first state. After receiving the indication information, the O-DU sends L1 signaling, L2 signaling, or L3 signaling to the terminal device to indicate that the terminal device changes from the RRC connected state to the first state.

[0204] In another possible implementation, the serving cell (or the network device to which the serving cell belongs) of the terminal device measures the uplink signal (e.g., uplink reference signal) sent by the terminal device. If the received strength of the uplink signal is less than or equal to a set threshold, it indicates that the terminal device may be located at the edge of the serving cell, and the network device to which the serving cell belongs can determine to change the terminal device from the RRC connected state to the first state.

[0205] In another possible implementation, the serving cell (or the network device to which the serving cell belongs) of the terminal device determines whether a state change is needed for the terminal device based on the channel state information reported by the terminal device. For example, if the channel state reported by the terminal device is lower than the set requirements, it indicates that the terminal device may be located at the edge of the serving cell, and the network device to which the serving cell belongs can determine to change the terminal device from the RRC connected state to the first state.

[0206] In one possible implementation, after determining that the terminal device will change from the RRC connected state to the first state, or after receiving the RRC state change confirmation information sent by the terminal device, the network device may modify the context information of the terminal device stored on the network device and record the current RRC state of the terminal device as the first state.

[0207] Step 703: The network device sends the first instruction information to the terminal device.

[0208] The first indication information is used to indicate a change from the RRC connection state to the first state.

[0209] Optionally, the first indication information is carried in L1 signaling, L2 signaling, or L3 signaling. L1 signaling is sent by the L1 layer (i.e., the physical layer), for example, L1 signaling can be downlink control information (DCI). L2 signaling is sent by the L2 layer (i.e., the MAC layer), for example, L2 signaling can be MAC CE (CE is an abbreviation for control element, i.e., control unit). L3 signaling is sent by the L3 layer (i.e., the RRC layer), for example, L3 signaling can be an RRC connection release message.

[0210] It is understood that the first instruction information can also be carried in other messages, and this application does not restrict this.

[0211] In the system architecture shown in Figure 2, in step 703, the CU (e.g., CU-CP) in the RAN sends F1 signaling to the DU. The F1 instruction may include indication information, which can be used to indicate a change to a first state. The DU sends the first indication information to the terminal device according to the F1 instruction.

[0212] Based on the system architecture shown in Figure 3, in step 701, the O-CU (e.g., O-CU-CP) in the RAN sends an F1 signaling to the O-DU. The F1 instruction may include indication information, which can be used to indicate a change to a first state. The O-DU sends the first indication information to the terminal device according to the F1 instruction.

[0213] Step 704: The terminal device enters the first state according to the first instruction information.

[0214] 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, which includes security configuration information.

[0215] In the first state, the terminal device can stop measuring periodic reference signals, such as stopping radio link monitoring (RLM) related operations. That is, there are no periodic downlink reference signals, such as periodic CSI-RS, at this time.

[0216] Optionally, the terminal device can also detect the periodic reference signal and select a cell based on the measurement results. Optionally, 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. See the foregoing embodiments for details.

[0217] Optionally, after receiving the first indication information, the terminal device may release or suspend a portion of the context information of the terminal device in the RRC connection state. For example, the portion of information may include one or more of the following: air interface context information related to data transmission, and periodic measurement configuration information.

[0218] Optionally, the terminal device can also send RRC status change confirmation information to the network device to notify the terminal device that it has changed to the first status.

[0219] In one possible implementation, in the first state, the terminal device can receive a reference signal that is transmitted along with the downlink data, perform channel measurement based on the reference signal, and send the channel measurement results to the network device.

[0220] Based on the system architecture shown in Figures 1, 2, or 3 above, and the RRC state transition diagram shown in Figure 5 or 6, Figure 8 illustrates another flowchart of a terminal device changing from the RRC connected state to the first state. 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.

[0221] As shown in Figure 8, the process may include the following steps:

[0222] Step 801: The terminal device in the RRC connected state sends a first request to the network device. The first request is used to request a change to the first state.

[0223] In one possible implementation, the terminal device can determine whether to change from the RRC connected state to the first state based on one or more factors such as the quality of the serving cell and service information, and send a first request when it determines to change to the first state. For details on how the terminal device determines whether to enter the first state based on the quality of the serving cell and / or service information, please refer to the relevant content in the process shown in Figure 7.

[0224] For example, the terminal device can measure downlink signals (e.g., downlink reference signals), such as the synchronization signal block (SSB). If, based on the measurement results, it determines that it needs to change from the RRC connected state to a first state, it sends a first request. For instance, if the measurement results indicate that the signal quality of the serving cell is greater than or equal to a threshold, it determines to enter the first state, i.e., sends a first request to the network device to which the serving cell belongs. Optionally, this threshold can be preset or configured on the network side.

[0225] As another example, the terminal device can measure the downlink signal (e.g., downlink reference signal) and count the amount of transmitted data. If, based on the measurement and statistical results, it determines that it is changing from the RRC connected state to the first state, it sends a first request. For example, if the measurement results indicate that the signal quality of the serving cell is greater than or equal to a threshold, and the trend of the buffered uplink data volume is decreasing, or the trend of the received downlink data volume is decreasing, then it determines that it is entering the first state, i.e., it sends a first request to the network device to which the serving cell belongs. Optionally, the threshold can be preset or configured on the network side.

[0226] Step 802: The network device changes the RRC status of the terminal device from the RRC connected state to the first state.

[0227] Taking the system architecture shown in Figure 2 as an example, the CU on the RAN side adds indication information to the F1 signaling to indicate the change to the first state; after receiving the indication information, the DU sends L1 signaling, L2 signaling, or L3 signaling to the terminal device to indicate that the terminal device changes from the RRC connected state to the first state.

[0228] Taking the system architecture shown in Figure 3 as an example, the O-CU (e.g., O-CU-UP) on the RAN side adds indication information to the F1 signaling to indicate the change to the first state; after receiving the indication information, the O-DU sends L1 signaling, L2 signaling, or L3 signaling to the terminal device to indicate that the terminal device changes from the RRC connected state to the first state.

[0229] In one possible implementation, after determining that the terminal device will change from the RRC connected state to the first state, or after receiving the RRC state change confirmation information sent by the terminal device, the network device may modify the context information of the terminal device stored on the network device and record the current RRC state of the terminal device as the first state.

[0230] Step 803: The network device sends the first instruction information to the terminal device.

[0231] The implementation method for this step can be referred to step 703 in the process shown in Figure 7.

[0232] Step 804: The terminal device enters the first state according to the first instruction information. 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, which includes security configuration information.

[0233] The implementation method for this step can be referred to step 704 in the process shown in Figure 7.

[0234] Based on the system architecture shown in Figures 1, 2, or 3 above, and the RRC state transition diagram shown in Figure 5 or 6, Figure 9 illustrates a flowchart of a terminal device changing from a first state to an RRC connected state. 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.

[0235] As shown in Figure 9, the process may include the following steps:

[0236] Step 901: The terminal device in the first state sends service information and / or state change tendency information to the network device.

[0237] This network device is the network device belonging to the serving cell of this terminal device.

[0238] For details on the content and acquisition method of the business information in this step, please refer to step 701 in the process shown in Figure 7.

[0239] In this step, the RRC status indicated by the status change tendency information is RRC connected state, which means that the terminal device recommends the RRC connected state.

[0240] Optionally, the state change preference information can be determined by the terminal device based on service information. For example, if the service information meets one or more of the following conditions, the terminal device may suggest a change from the first state to the RRC connected state:

[0241] Condition 1: The total data volume of the services corresponding to this terminal device exceeds the data volume threshold, indicating that the downlink data transmission volume of this terminal device is large. In this case, in order to ensure data transmission efficiency, the device can be changed from the first state to the RRC connection state.

[0242] Condition 2: The duration of the service corresponding to the terminal device (i.e., data transmission duration) is greater than the duration threshold, indicating that the downlink data transmission duration of the terminal device is relatively long. In this case, in order to ensure data transmission efficiency, the device can be changed from the first state to the RRC connection state.

[0243] Condition 3: The data volume of the service corresponding to this terminal device shows an upward trend, indicating that the downlink data transmission volume of this terminal device is gradually increasing. In this case, to ensure data transmission efficiency, the device can be switched from the first state to the RRC connection state.

[0244] Condition 4: The service type corresponding to this terminal device is not the service type specified in the configuration information of the first state, indicating that the downlink data transmission volume of this terminal device is large, the duration is long, or the data transmission efficiency requirement is high. In this case, in order to ensure data transmission efficiency, it can be changed from the first state to the RRC connection state.

[0245] Condition 5: The QoS level of the service corresponding to this terminal device is higher than the QoS level threshold, indicating that the downlink data transmission of this terminal device has high requirements for data transmission efficiency. In this case, in order to ensure data transmission efficiency, the device can be changed from the first state to the RRC connection state.

[0246] It should be understood that the above are merely examples of several conditions that may cause the terminal device to change from the first state to the RRC connected state, and this application does not impose any restrictions on them.

[0247] Optionally, the state change tendency information may include indication information of the RRC state that the terminal device tends to. For example, in this process, the state change tendency information may be indication information of the first state.

[0248] Optionally, the state change tendency information may also include second duration information, which indicates the duration of the RRC state (taking the RRC connected state as an example) suggested by the terminal device. The network device can determine the duration for which the terminal device is in the RRC connected state based on the second duration information.

[0249] In one possible implementation, after obtaining service information, the terminal device may send the service information and / or state change tendency information to the network device only if certain conditions are met. If these conditions are not met, the terminal device will not send the service information or state change tendency information to the network device. Optionally, these conditions may include one or more of the following:

[0250] Condition a: The data volume of the service corresponding to the terminal device is greater than or equal to the threshold. Optionally, the threshold may be equal to or different from the aforementioned data volume threshold. This application does not impose any restrictions on this.

[0251] Condition b: The data volume of the service corresponding to this terminal device shows an upward trend;

[0252] Condition c: The duration of the service corresponding to the terminal device is greater than the duration threshold.

[0253] Based on the system architecture shown in Figure 2, in step 901, the terminal device sends service information and / or state change tendency information to the CU (e.g., CU-CP). The CU can determine in subsequent steps whether to change the terminal device from H-EDT state to RRC connection state based on the service information and / or state change tendency information.

[0254] Based on the system architecture shown in Figure 3, in step 901, the terminal device sends service information and / or state change tendency information to the O-CU (e.g., O-CU-CP). The O-CU can determine in subsequent steps whether to change the terminal device from H-EDT state to RRC connection state based on the service information and / or state change tendency information.

[0255] Step 901 is an optional step.

[0256] Step 902: The network device determines to change the RRC status of the terminal device from the first state to the RRC connected state.

[0257] In one possible implementation, the network device can determine whether to change the terminal device from the first state to the RRC connection state based on the service information sent by the terminal device. The method by which the network device determines whether to change the terminal device from the first state to the RRC connection state based on the service information can refer to the method in step 901 for the terminal device to determine whether to change from the first state to the RRC connection state.

[0258] In another possible implementation, the network device can determine whether to change the terminal device from the RRC connected state to the RRC state indicated by the state change tendency information sent by the terminal device.

[0259] In another possible implementation, the network device can determine whether to change the terminal device from the RRC connected state to the first state based on the service information corresponding to the terminal device obtained from the core network. The content of this service information can be found in the relevant description of the service information in step 701.

[0260] In another possible implementation, the network device can determine whether to change the terminal device from the first state to the RRC connected state based on the amount of service data or the trend of data volume changes received from the core network. For example, if the network device determines that the amount of service data corresponding to the terminal device is greater than a data volume threshold, it decides to change the terminal device from the first state to the RRC connected state. As another example, if the network device determines that the trend of data volume changes for the service corresponding to the terminal device is upward, it decides to change the terminal device from the first state to the RRC connected state.

[0261] In another possible implementation, the serving cell (or the network device to which the serving cell belongs) of the terminal device measures the uplink signal (e.g., uplink reference signal) sent by the terminal device. If the received strength of the uplink signal is greater than a set threshold, the network device to which the serving cell belongs can determine to change the terminal device from the first state to the RRC connected state.

[0262] In another possible implementation, the serving cell (or the network device to which the serving cell belongs) of the terminal device determines whether a state change is needed for the terminal device based on the channel state information reported by the terminal device. For example, if the channel state reported by the terminal device meets the set requirements, the network device to which the serving cell belongs can determine to change the terminal device from the first state to the RRC connected state.

[0263] Taking the system architecture shown in Figure 2 as an example, the CU on the RAN side receives downlink data. When the CU sends the data to the DU, it adds indication information to the F1 signaling to indicate that the trend of the buffered data volume is increasing, or to indicate a change to the RRC connection state. After receiving the indication information, the DU sends L1 signaling, L2 signaling, or L3 signaling to the terminal device to indicate that the terminal device changes from the first state to the RRC connection state.

[0264] Taking the system architecture shown in Figure 3 as an example, the O-CU (e.g., O-CU-UP) on the RAN side receives downlink data. When the O-CU sends the data to the O-DU, it adds indication information to the F1 signaling to indicate that the trend of the buffered data volume is increasing, or to indicate a change to the RRC connection state. After receiving the indication information, the O-DU sends L1 signaling, L2 signaling, or L3 signaling to the terminal device to indicate that the terminal device changes from the first state to the RRC connection state.

[0265] In one possible implementation, after determining that the terminal device should be changed from the first state to the RRC connected state, the network device can modify the context information of the terminal device stored on the network device and record the current RRC state of the terminal device as the RRC connected state.

[0266] Step 903: The network device sends a second instruction message to the terminal device.

[0267] The second indication information is used to indicate a change from the first state to the RRC connection state.

[0268] Optionally, the second indication information is carried in L1 signaling, L2 signaling, or L3 signaling. L1 signaling is sent by the L1 layer (i.e., the physical layer), for example, L1 signaling could be DCI; L2 signaling is sent by the L2 layer (i.e., the MAC layer), for example, L2 signaling could be MAC CE; and L3 signaling is sent by the L3 layer (i.e., the RRC layer), for example, L3 signaling could be an RRC Reconfigure message.

[0269] Optionally, when the network device instructs the terminal device to change from the first state to the RRC connected state via an RRC reconfiguration message, the RRC reconfiguration message contains RRC connected state configuration information, such as configuration information for periodic reference signals and periodic measurement configuration, so that the terminal device can perform connected state-related operations based on the configuration information and change to the RRC connected state.

[0270] Optionally, when the network device instructs the terminal device to change from the first state to the RRC connected state via a DCI, the DCI can instruct the terminal device to restore the suspended context information. For example, in the first state, the terminal device may have suspended the following context information: RRC connected state configuration information, such as configuration information for periodic reference signals, periodic measurement configuration information, and periodic measurement reporting configuration information. When the terminal device receives the DCI, it can restore the suspended context information according to the DCI's instruction, thereby restoring the RRC connection.

[0271] It is understood that the second indication information can also be carried in other messages, and optionally, the other messages may contain RRC connection state configuration information.

[0272] In the system architecture shown in Figure 2, in step 903, the CU (e.g., CU-CP) in the RAN sends an F1 signaling message to the DU. The F1 instruction may include indication information, which can be used to indicate a change to RRC connection state. The DU sends a second indication information to the terminal device according to the F1 instruction.

[0273] Based on the system architecture shown in Figure 3, in step 901, the O-CU (e.g., O-CU-CP) in the RAN sends an F1 signaling message to the O-DU. The F1 instruction may include indication information, which can be used to indicate a change to RRC connection state. The O-DU sends a second indication information to the terminal device according to the F1 instruction.

[0274] Step 904: The terminal device enters the RRC connection state according to the second instruction information. In the RRC connection state, the terminal device restores the context information of the RRC connection state.

[0275] Optionally, the terminal device can also send RRC status change confirmation information to the network device to notify the terminal device to change to RRC connection state.

[0276] In one possible implementation, if the terminal device stops measuring the periodic reference signal in the first state, then in the RRC connection state, the terminal device resumes the measurement of the periodic reference signal. In another possible implementation, if the terminal device measures the periodic reference signal in the first state but the measurement period is longer than the measurement period in the RRC connection state, then in the RRC connection state, the terminal device resumes using the measurement period as in the RRC connection state.

[0277] In one possible implementation, in RRC connected state, the terminal device no longer detects the accompanying reference signal. In RRC connected state, the terminal device can resume transmitting periodic uplink reference signals to the network device, which can then perform channel measurements based on these uplink reference signals. Similarly, in RRC connected state, the network device can resume transmitting periodic downlink reference signals to the terminal device, which can then perform channel measurements based on these downlink reference signals.

[0278] Based on the system architecture shown in Figures 1, 2, or 3 above, and the RRC state transition diagram shown in Figure 5 or 6, Figure 10 illustrates another flowchart of a terminal device changing from the first state to the RRC connected state. 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.

[0279] As shown in Figure 10, the process may include the following steps:

[0280] Step 1001: The terminal device in the first state sends a second request to the network device, which is used to request a change to the RRC connection state.

[0281] In this step, the terminal device sends a second request after determining that it has changed from the first state to the RRC connection state.

[0282] In one possible implementation, the terminal device can determine whether to change from the first state to the RRC connected state based on the quality and / or service information of the serving cell, and send a second request when it determines to change to the RRC connected state. For details on how the terminal device determines whether to enter the RRC connected state based on the quality and / or service information of the serving cell, please refer to the relevant content in the process shown in Figure 9.

[0283] In another possible implementation, the terminal device can measure downlink signals (e.g., downlink reference signals), such as SSB measurements. If, based on the measurement results, it determines that the device is changing from the first state to the RRC connected state, it sends a second request. For example, if the measurement results indicate that the signal quality of the serving cell is higher than a threshold, it determines to enter the RRC connected state, i.e., it sends a second request to the network device to which the serving cell belongs. Optionally, this threshold can be preset or configured on the network side.

[0284] In another possible implementation, the terminal device can measure the downlink signal (e.g., downlink reference signal) and count the amount of transmitted data. If, based on the measurement and statistical results, it determines that it needs to change from the first state to the RRC connected state, it sends a second request. For example, if the measurement results indicate that the signal quality of the serving cell is higher than a threshold, and the trend of the buffered uplink data volume or the trend of the received downlink data volume is upward, then it determines to enter the RRC connected state, i.e., sends a second request to the network device to which the serving cell belongs. Optionally, this threshold can be preset or configured on the network side.

[0285] In one possible implementation, the second request could be an RRC connection restoration request or an RRC establishment request message.

[0286] Step 1002: The network device changes the RRC status of the terminal device from the first state to the RRC connected state.

[0287] Taking the system architecture shown in Figure 2 as an example, the CU on the RAN side adds indication information to the F1 signaling to indicate the change to RRC connection state; after receiving the indication information, the DU sends L1 signaling, L2 signaling, or L3 signaling to the terminal device to indicate the terminal device to change from the first state to the RRC connection state.

[0288] Taking the system architecture shown in Figure 3 as an example, the O-CU (e.g., O-CU-UP) on the RAN side adds indication information to the F1 signaling to indicate the change to RRC connection state; after receiving the indication information, the O-DU sends L1 signaling, L2 signaling, or L3 signaling to the terminal device to indicate the terminal device to change from the first state to the RRC connection state.

[0289] In one possible implementation, after determining that the terminal device should be changed from the RRC connected state to the first state, or after receiving a second request from the terminal device, the network device may modify the context information of the terminal device stored on the network device and record the current RRC state of the terminal device as the RRC connected state.

[0290] Step 1003: The network device sends a second instruction message to the terminal device.

[0291] The implementation method for this step can be found in step 903 of the process shown in Figure 9.

[0292] In one possible implementation, if the terminal device sends an RRC connection recovery request or RRC establishment request message to the network device in step 1002, then in step 1003, the network device sends a response message to the terminal device, such as an RRC connection establishment, RRC connection recovery, or RRC reconfiguration message, which includes second indication information.

[0293] Step 1004: The terminal device enters the RRC connection state according to the second instruction information.

[0294] In RRC connection mode, restore the context information of the RRC connection mode.

[0295] In one possible implementation, if the terminal device receives a response message from the network device in step 1003, such as an RRC connection establishment, RRC connection recovery, or RRC reconfiguration message, the terminal device may send an RRC connection establishment complete message, recovery complete message, or RRC reconfiguration complete message to the network device in step 1004.

[0296] The implementation method for this step can be found in step 904 of the process shown in Figure 9.

[0297] Based on the system architecture shown in Figures 1, 2, or 3 above, and the RRC state transition diagram shown in Figure 5 or 6, Figure 11 illustrates a flowchart of a terminal device changing from a first state to an RRC inactive state. 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.

[0298] As shown in Figure 11, the process may include the following steps:

[0299] Step 1101: The network device determines to change the RRC state of the terminal device from the first state to the RRC inactive state.

[0300] Optionally, when a network device determines that a terminal device has not transmitted data for an extended period of time, it may decide to change the terminal device from the first state to the RRC inactive state in order to save power consumption.

[0301] Step 1102: The network device sends a third instruction message to the terminal device.

[0302] The third indication information is used to indicate the change from the first state to the RRC inactive state.

[0303] Optionally, the third indication information is carried in L3 signaling. This L3 signaling is sent by the L3 layer (i.e., the RRC layer). For example, the L3 signaling is an RRC message; more specifically, it is an RRC connection release message.

[0304] Step 1103: The terminal device enters the RRC inactive state according to the third instruction information.

[0305] In some other embodiments, the terminal device may send a request message to the network device to request a change to the RRC inactive state; the network device sends a third indication message to the terminal device according to the request of the terminal device, thereby causing the terminal device to change from the first state to the RRC inactive state.

[0306] In other embodiments, the terminal device and the network device maintain timers respectively, ensure timer synchronization, and switch between a first state and an RRC inactive state based on the timers respectively.

[0307] Based on the system architecture shown in Figures 1, 2, or 3 above, and the RRC state transition diagram shown in Figure 5 or 6, Figure 12 illustrates a flowchart of a terminal device changing from an inactive RRC state to a first state. 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.

[0308] As shown in Figure 12, the process may include the following steps:

[0309] Step 1201: The network device determines to change the RRC state of the terminal device from the RRC inactive state to the first state.

[0310] Optionally, when a network device determines that a terminal device has a data transmission requirement, it can decide to change the terminal device from the RRC inactive state to the first state in order to realize data transmission.

[0311] Step 1202: The network device sends the fourth instruction information to the terminal device.

[0312] The fourth indication information is used to indicate a change from the first state to the RRC inactive state.

[0313] Optionally, the fourth indication information is carried in L3 signaling.

[0314] Step 1203: The terminal device enters the first state according to the fourth instruction information.

[0315] In some other embodiments, the terminal device may send a request message to the network device to request a change to a first state; the network device sends a fourth indication message to the terminal device according to the request of the terminal device, thereby causing the terminal device to change from the RRC inactive state to the first state.

[0316] In another 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.

[0317] 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.

[0318] In some other embodiments, the terminal device may also change from a first state to an RRC idle state according to the instructions of the network device.

[0319] 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.

[0320] Figures 13 and 14 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.

[0321] As shown in Figure 13, the communication device 1300 includes a processing unit 1310 and a transceiver unit 1320. The communication device 1300 is used to implement the functions of the terminal device or network device in the method embodiments shown in any of the figures 7 to 12 above.

[0322] When the communication device 1300 is used to implement the function of the terminal device in the method embodiment shown in FIG7 or FIG8: the transceiver unit 1320 is used to receive first indication information, the first indication information indicating that the terminal device changes from the RRC connection state to the first state; the processing unit 1310 is used to enter the first state according to the first indication information, the context information saved by the terminal device in the first state includes part of the context information saved by the terminal device in the RRC connection state, the part of the context information includes security configuration information.

[0323] When the communication device 1300 is used to implement the function of the network device in the method embodiment shown in FIG7 or FIG8: the processing unit 1310 is used to send first indication information through the transceiver unit 1320, the first indication information indicating that the terminal device changes from the RRC connection state to a first state; the context information saved by the terminal device in the first state includes a portion of the context information saved by the terminal device in the RRC connection state, the portion of the context information including security configuration information; the processing unit 1310 is also used to release or suspend the portion of the context information saved by the network device in the RRC connection state of the terminal device.

[0324] When the communication device 1300 is used to implement the functions of the terminal device in the method embodiment shown in FIG9 or FIG10: In the first state, the transceiver unit 1320 receives second indication information, which is used to instruct the terminal device to change from the first state to the RRC connection state; the processing unit 1310 is used to enter the RRC connection state according to the second indication information, and the terminal device restores the context information of the RRC connection state and restores the measurement of the reference signal of the period under the RRC connection. 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.

[0325] When the communication device 1300 is used to implement the functions of the network device in the method embodiment shown in FIG9 or FIG10: when the terminal device is in the first state, the processing unit 1310 is used to send second indication information through the transceiver unit 1320, the second indication information being used to instruct the terminal device to change from the first state to the RRC connection state; the processing unit 1310 is also used to restore the context information of the terminal device in the RRC connection state saved by the network device. The context information saved by the terminal device in the first state includes a portion of the context information saved by the terminal device in the RRC connection state, and the portion of the context information includes security configuration information.

[0326] When the communication device 1300 is used to implement the functions of the terminal device in the method embodiment shown in FIG11: when the terminal device is in a first state, the transceiver unit 1320 is used to receive third indication information, the third indication information being used to instruct the terminal device to change from the first state to the RRC inactive state; the processing unit 1310 is used to enter the RRC inactive state according to the third indication information. In the first state, the terminal device stops measuring the periodic reference signal, and 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 connected state, the portion of the context information including security configuration information.

[0327] When the communication device 1300 is used to implement the functions of the network device in the method embodiment shown in FIG11: when the terminal device is in a first state, the processing unit 1310 is used to send third indication information through the transceiver unit 1320. The third indication information is used to instruct the terminal device to change from the first state to the RRC inactive state. In the first state, the terminal device stops measuring the periodic reference signal. 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 connected state, and the portion of the context information includes security configuration information.

[0328] When the communication device 1300 is used to implement the functions of the terminal device in the method embodiment shown in FIG12: when the terminal device is in the RRC inactive state, the transceiver unit 1320 is used to receive fourth indication information, which is used to instruct the terminal device to change from the RRC inactive state to the first state; the processing unit 1310 is used to enter the first state according to the fourth indication information. In the first state, the terminal device stops measuring the periodic reference signal, and 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 connected state, which includes security configuration information.

[0329] When the communication device 1300 is used to implement the function of the network device in the method embodiment shown in FIG12: when the terminal device is in the RRC inactive state, the processing unit 1310 is used to send fourth indication information through the transceiver unit 1320. The fourth indication information is used to instruct the terminal device to change from the RRC inactive state to the first state. In the first state, the terminal device stops measuring the periodic reference signal. 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 connected state, and the portion of the context information includes security configuration information.

[0330] A more detailed description of the processing unit 1310 and the transceiver unit 1320 can be obtained directly from the description in the method embodiment shown in the relevant drawings, and will not be repeated here.

[0331] As shown in Figure 14, the communication device 1400 includes a processor 1410 and an interface circuit 1420. The processor 1410 and the interface circuit 1420 are coupled to each other. It is understood that the interface circuit 1420 can be a transceiver or an input / output interface. Optionally, the communication device 1400 may further include a memory 1430 for storing instructions executed by the processor 1410, or storing input data required by the processor 1410 to execute instructions, or storing data generated after the processor 1410 executes instructions.

[0332] When the communication device 1400 is used to implement the method shown in FIG3, the processor 1410 is used to implement the function of the processing unit 1310, and the interface circuit 1420 is used to implement the function of the transceiver unit 1320.

[0333] 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.

[0334] 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.

[0335] 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.

[0336] 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 FIG14, the communication device 1400 includes a processor 1410 and a memory 1430. The processor 1410 and the memory 1430 are coupled together. The memory 1430 stores instructions. When the instructions stored in the memory 1430 are executed by the processor 1410, the communication device 1400 performs the methods performed by the terminal device or network device described in the above embodiments.

[0337] 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.

[0338] 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.

[0339] 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.

[0340] 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.

[0341] 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: Receive a first indication information, the first indication information instructing the terminal device to change from the Radio Resource Control (RRC) connected state to a first state; Entering the first state according to the first instruction information, in the first state, the context information saved by the terminal device in the first state includes part of the context information saved by the terminal device in the RRC connection state, and the part 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, After receiving the first indication information, the process further includes: Release or suspend one or more of the following context information of the terminal device in RRC connection state: air interface context information related to data transmission, periodic measurement configuration information.

4. The method according to any one of claims 1-3, characterized in that, Before receiving the first indication information, the method further includes: Send a first request, which is used to request entry into the first state.

5. The method as described in claim 4, characterized in that, Sending the first request includes: Based on the quality and / or service information of the serving cell, determine the change from RRC connected state to the first state, and send the first request; or Based on measurements of the downlink signal, a change from RRC connected state to the first state is determined, and the first request is sent; or Based on the measurement of the downlink signal and the statistics of the transmitted data volume, it is determined that the connection state has changed from the RRC connection state to the first state, and the first request is sent.

6. The method according to any one of claims 1-5, characterized in that, In the first state, the terminal device further includes: Receive a second indication information, the second indication information being used to instruct the terminal device to change from the first state to the RRC connection state; Upon entering the RRC connection state according to the second instruction information, the terminal device restores the context information of the RRC connection state and resumes the measurement of the reference signal for the period under the RRC connection.

7. The method according to any one of claims 1-5, characterized in that, When the terminal device is in the first state, it further includes: Receive a third indication message, the third indication message being used to instruct the terminal device to change from the first state to the RRC inactive state; Enter the RRC inactive state according to the third instruction information.

8. The method as described in claim 7, characterized in that, When the terminal device is in the RRC inactive state, it also includes: Receive a fourth indication message, the fourth indication message being used to instruct the terminal device to change from the RRC inactive state to the first state; Enter the first state according to the fourth instruction information.

9. The method according to any one of claims 1-8, characterized in that, The first state includes a first mode and / or a second mode. When the terminal device is in the first mode, it performs data transmission, and when the terminal device is in the second mode, it does not transmit data.

10. The method as described in claim 9, characterized in that, When the terminal device is in the first mode, it further includes: performing data transmission; receiving fifth indication information, and changing from the first mode to the second mode according to the fifth indication information, wherein the fifth indication information is used to indicate that the terminal device has changed from the first mode to the second mode, or to indicate that data transmission is complete; or When the terminal device is in the second mode, it further includes: receiving sixth instruction information; and changing from the second mode to the first mode according to the sixth instruction information.

11. The method as described in claim 9, characterized in that, Also includes: Upon receiving signaling for data transmission scheduling, a timer is started, and during the operation of the timer, the terminal device is in the first mode; When the timer expires, the system switches from the first mode to the second mode.

12. The method according to any one of claims 1-11, characterized in that, When the terminal device is in the first state, it further includes: When switching or changing from a source cell to a target cell, the source cell and the target cell belong to the same area; An access request or update indication is sent to the target cell. The access request and the update indication are used to trigger the target cell to send a UE change cell indication to the source cell. The UE change cell indication is used to trigger the source cell to send the saved context information of the terminal device to the target cell.

13. A communication method, characterized in that, Applied to network devices, including: Send a first indication message, the first indication message instructing the terminal device to change from the Radio Resource Control (RRC) connected state to a first state; in the first state, the terminal device stops measuring the periodic reference signal, and 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 connected state, the portion of the context information including security configuration information; Release or suspend a portion of the context information of the terminal device in the RRC connection state stored by the network device.

14. The method as described in claim 13, 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.

15. The method according to any one of claims 13-14, characterized in that, The release or suspension of a portion of the context information of the terminal device in RRC connection state stored by the network device includes: Release or suspend one or more of the following context information of the terminal device in RRC connection state stored by the network device: air interface context information related to data transmission, periodic measurement configuration information.

16. The method according to any one of claims 13-15, characterized in that, Before sending the first indication information, the method further includes: Receive a first request, which is used to request to enter the first state; The sending of the first instruction information includes: Send the first instruction information according to the first request.

17. The method according to any one of claims 13-16, characterized in that, In the first state, the terminal device further includes: Send a second indication message, the second indication message being used to instruct the terminal device to change from the first state to the RRC connection state; Restore the context information of the terminal device in the RRC connection state saved by the network device.

18. The method according to any one of claims 13-16, characterized in that, When the terminal device is in the first state, it further includes: Send a third indication message, which is used to instruct the terminal device to change from the first state to the RRC inactive state.

19. The method as described in claim 18, characterized in that, When the terminal device is in the RRC inactive state, it also includes: Send a fourth indication message, which is used to instruct the terminal device to change from the RRC inactive state to the first state.

20. The method according to any one of claims 13-19, characterized in that, The first state includes a first mode and / or a second mode. When the terminal device is in the first mode, it performs data transmission, and when the terminal device is in the second mode, it does not transmit data.

21. The method as described in claim 20, characterized in that, When the terminal device is in the first mode, it further includes: Perform data transmission; Send a fifth instruction message, which is used to instruct the terminal device to change from the first mode to the second mode, or to indicate that data transmission is complete.

22. The method as described in claim 21, characterized in that, When the terminal device is in the second mode, it further includes: Send a sixth instruction message, which is used to instruct the terminal device to change from the second mode to the first mode.

23. The method as described in claim 20, characterized in that, Also includes: Send signaling for data transmission scheduling, start a timer, and during the operation of the timer, set the terminal device to a first mode; When the timer expires, the terminal device is changed from the first mode to the second mode.

24. The method according to any one of claims 13-23, characterized in that, When the terminal device is in the first state, it further includes: Receive a UE cell change instruction from a target cell, the UE cell change instruction being used to instruct the terminal device to switch from a source cell to the target cell, the source cell and the target cell belonging to the same area; send the context information of the terminal device to the target cell according to the UE cell change instruction; or A handover request is sent to the terminal device, the handover request being used to instruct the terminal device to hand over or change from the source cell to the target cell, and the context information of the terminal device stored by the network device is sent to the target cell.

25. The method according to any one of claims 9-11 and 20-23, characterized in that, In the second mode, the fourth context information is released or suspended; in the first mode, the fourth context information is restored. and / or In the first mode, a first search space configuration information is applied, and in the second mode, a second search space configuration information is applied; wherein the search period length indicated by the first search space configuration information is less than the search period length indicated by the second search space configuration information.

26. The method as described in claim 25, characterized in that, The fourth context information includes one or more of the following: security key, data packet sequence number, and data transmission related variables, wherein the data transmission related variables are used to determine the time window for data transmission.

27. The method according to any one of claims 1-26, characterized in that, The security configuration information includes one or more of the following: next-hop chain calculation, security key.

28. The method according to any one of claims 1-27, 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.

29. The method according to any one of claims 1-28, 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.

30. A communication device, characterized in that, include: One or more processors are configured to perform the method as claimed in any one of claims 1-12, 25-29, or the method as claimed in any one of claims 13-29.

31. A communication device, characterized in that, It includes a unit or module for performing the method as described in any one of claims 1-12, 25-29, or includes a unit or module for performing the method as described in any one of claims 13-29.

32. A computer-readable storage medium, characterized in that, The computer-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 1-12, 25-29, or the method as claimed in any one of claims 13-29.

33. 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 1-12, 25-29, or in implementing the method as described in any one of claims 13-29.

34. 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 1-12, 25-29, or to perform the method as described in any one of claims 13-29.

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