A communication method and related apparatus

Abstract

This application provides a communication method and related apparatus. The method is applied to a terminal in a non-Radio Resource Control (RRC) connected state, comprising: executing an RRC connection recovery process for Notification Area Update (RNAU) based on the Radio Access Network when a first preset condition is met; the first preset condition includes a second timer timeout and a first timer not running; or the first preset condition includes the terminal receiving a System Information Block (SIB1) of a serving cell, the serving cell not belonging to the configured Notification Area based on the Radio Access Network, and the first timer not running; the first timer is started when the terminal initiates an RRC connection recovery process for Small Packet Data Transmission (SDT), and the second timer is started when the terminal receives an RRC release message including the duration of the second timer. This application can avoid triggering RNAU during the SDT process, thereby avoiding impact on the transmission of small packet data and unnecessary power consumption and signaling overhead.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a communication method and related apparatus. Background Technology

[0002] In a communication system, the communication protocol stack between a terminal and network devices may include a radio resource control (RRC) layer. Currently, there are three RRC states for terminals: RRC IDLE, RRC INACTIVE, and RRC CONNECTED. A terminal in the RRC INACTIVE state can transmit small data packets to network devices through the RRC connection recovery process, a process known as small data transmission (SDT). When a terminal is in the RRC INACTIVE state, the radio access network (RAN) can manage the RAN-based notification area (RNA). For example, the terminal can trigger an RNA update (RNAU) and execute the RRC connection recovery process for the RNAU to notify the network device of the terminal's current RNA state.

[0003] When a terminal performs SDT, it may trigger the execution of RNAU. In this case, the terminal may stop the current SDT and execute RNAU, which will affect the transmission of small data, such as increasing the transmission latency. Subsequent SDT initiation will also increase power consumption and signaling overhead. Summary of the Invention

[0004] This application discloses a method and related apparatus for controlling transmission, which can avoid affecting the transmission of small packet data, as well as unnecessary power consumption and signaling overhead.

[0005] In a first aspect, embodiments of this application provide a method for controlling transmission, applied to a terminal in a non-Radio Resource Control (RRC) connection state. The method includes: when a first preset condition is met, executing an RRC connection recovery process for Notification Area Update (RNAU) based on a Radio Access Network; wherein the first preset condition includes a second timer timeout and a first timer not running; or, the first preset condition includes the terminal receiving a System Information Block (SIB1) of a first serving cell, the first serving cell not belonging to a configured Notification Area (RNAU) based on a Radio Access Network, and the first timer not running; wherein the first timer is started when the terminal initiates an RRC connection recovery process for Small Packet Data Transmission (SDT), and the second timer is started when the terminal receives an RRC release message including the duration of the second timer.

[0006] In some embodiments, the RRC connection recovery process for RNAU includes sending an RRC request message in which the recovery cause information element IE is set to rna-Update.

[0007] For example, the second timer is T380.

[0008] In this application, RNAU will not be executed when the first timer is running (i.e. during SDT). During SDT, the network device can obtain the RNA where the terminal is located. Not executing RNAU will not only not affect the network device's acquisition of the terminal's status, but also avoid affecting the transmission of small packet data during the SDT process. For example, it can avoid increasing transmission latency and avoid unnecessary signaling overhead and power consumption when re-initiating SDT.

[0009] In one possible implementation, the first timer not running is defined as the first timer not being enabled.

[0010] In some embodiments, the fact that the first timer is not enabled indicates that there is no need for SDT.

[0011] In one possible implementation, before executing the Radio Resource Control (RRC) connection recovery process for Notification Area Update (RNAU) based on the Radio Access Network when the first preset condition is met, the method further includes: initiating the RRC connection recovery process for SDT and starting the first timer; when cell reselection occurs, stopping the first timer; the first preset condition includes the first timer not running and the serving cell of the terminal not belonging to the configured RNA, the first timer not running means the first timer is stopped, and the serving cell of the terminal is the serving cell after the terminal has undergone cell reselection.

[0012] In some embodiments, the RRC connection recovery process for SDT includes sending an RRC request message in which resumeCause IE is mo-data.

[0013] In one possible implementation, the first preset condition further includes: the terminal is in an RRC inactive state; and / or, the terminal cannot perform the SDT process in the serving cell.

[0014] In some embodiments, the terminal cannot perform an SDT procedure in the serving cell, including: the terminal cannot continue a previous SDT procedure in the serving cell. In some embodiments, the terminal cannot perform an SDT procedure in the serving cell, including: the terminal cannot initiate a new SDT procedure in the serving cell.

[0015] In one possible implementation, the method further includes: if an RRC rejection message is received while the first timer is running, stopping the first timer; if the second timer is not running, setting a first variable to a first value, wherein the first variable being the first value indicates an pending RNA update process.

[0016] In this application, if the second timer times out while the first timer is running (i.e., during SDT), the terminal will not execute RNAU, nor will it set the first variable to the first value, thereby avoiding affecting the currently running SDT process. When the SDT process ends abnormally (e.g., the first timer stops or times out), and the second timer does not run, the terminal can set the first variable to the first value so that RNAU can be executed normally subsequently.

[0017] In one possible implementation, the method further includes: if an RRC rejection message is received while the first timer is running, stopping the first timer; if the second timer is not running, executing the Radio Resource Control (RRC) connection recovery process for RNAU.

[0018] In this application, if the second timer times out while the first timer is running (i.e., during SDT), the terminal will not execute RNAU, thereby avoiding affecting the currently running SDT process. When the SDT process ends abnormally (e.g., the first timer stops or times out) and the second timer has not run, the terminal will then execute RNAU to ensure its normal execution.

[0019] In one possible implementation, the method further includes: if an RRC rejection message is received while the first timer is running, stopping the first timer; if the second timer is not running, starting a third timer; and when the third timer times out, if the first timer is not running, executing the RRC connection recovery process for RNAU.

[0020] In one possible implementation, the duration of the third timer is the same as that of the second timer.

[0021] In one possible implementation, the duration of the third timer is different from that of the second timer.

[0022] In one possible implementation, the non-Radio Resource Control (RRC) connection state is an RRC inactive state; after receiving an RRC rejection message, the terminal is in the RRC inactive state.

[0023] In this application, if the second timer times out while the first timer is running (i.e., during SDT), the terminal will not execute RNAU, nor will it start the third timer, thus avoiding affecting the currently ongoing SDT process. If the SDT process ends abnormally (e.g., the first timer stops or times out), and the second timer does not run, the terminal can start the third timer. When the third timer times out and the first timer does not run, the Radio Resource Control (RRC) connection recovery process for RNAU is then executed to ensure the normal execution of RNAU.

[0024] In one possible implementation, the method further includes: when the first timer times out, if the second timer has not run, setting a first variable to a first value, wherein the first variable being the first value indicates an pending RNA update process.

[0025] In one possible implementation, the method further includes: when the first timer times out, if the second timer has not run, executing the Radio Resource Control (RRC) connection recovery process for RNAU.

[0026] In one possible implementation, the method further includes: when the first timer times out, if the second timer has not run, starting a third timer; when the third timer times out, if the first timer has not run, executing the RRC connection recovery process for RNAU.

[0027] In one possible implementation, the duration of the third timer is the same as that of the second timer.

[0028] In one possible implementation, the duration of the third timer is different from that of the second timer.

[0029] In one possible implementation, the non-radio resource control (RRC) connected state is an RRC inactive state; after the first timer expires, the terminal is in the RRC inactive state.

[0030] In one possible implementation, the method further includes: when the first timer is running, if a cell reselection occurs, stopping the first timer; receiving SIB1 of a second serving cell, the second serving cell being the serving cell after the cell reselection of the terminal; when the SIB1 of the second serving cell is received, if the second serving cell belongs to a configured RNA and the second timer is not running, setting a first variable to a first value, the first variable being the first value indicating an pending RNA update process.

[0031] In one possible implementation, the method further includes: if cell reselection occurs while the first timer is running, stopping the first timer; receiving SIB1 of a second serving cell, wherein the second serving cell is the serving cell after the cell reselection of the terminal; and when SIB1 of the second serving cell is received, if the second serving cell belongs to the configured RNA and the second timer is not running, executing the Radio Resource Control (RRC) connection recovery process for RNAU.

[0032] In one possible implementation, the method further includes: when the first timer is running, if cell reselection occurs, stopping the first timer; receiving SIB1 of the second serving cell, the second serving cell being the serving cell after the cell reselection of the terminal; when the SIB1 of the second serving cell is received, if the second serving cell belongs to the configured RNA and the second timer is not running, starting a third timer; when the third timer times out, if the first timer is not running, executing the RRC connection recovery process for RNAU.

[0033] In one possible implementation, the duration of the third timer is the same as that of the second timer.

[0034] In one possible implementation, the duration of the third timer is different from that of the second timer.

[0035] In one possible implementation, the non-radio resource control (RRC) connected state is an RRC inactive state; after the terminal undergoes cell reselection, the terminal is in the RRC inactive state.

[0036] In one possible implementation, after setting the first variable to the first value, the method further includes: if the access ban is mitigated and the non-access NAS layer does not request the RRC layer to perform RRC connection restoration, and if the first variable is the first value, executing the RRC connection restoration process for RNAU.

[0037] In one possible implementation, the non-radio resource control (RRC) connected state is an RRC inactive state.

[0038] Secondly, this application provides another method for controlling transmission, applied to a terminal in a non-RRC connection state. The method includes: when a first preset condition is met, setting a first variable to a first value, wherein the first variable and the first value indicate an pending RNA update process, wherein the first preset condition includes a first timer not running, and the first timer being started when the terminal receives an RRC release message including the duration of the first timer.

[0039] For example, the first timer is T380.

[0040] In one possible implementation, the first preset condition further includes the terminal receiving an RRC rejection message while the second timer is running; the second timer is started when the terminal initiates an RRC connection recovery process for SDT, and the second timer is stopped when the terminal receives the RRC rejection message.

[0041] In one possible implementation, the first preset condition further includes a second timer timeout, which is activated when the terminal initiates an RRC connection recovery process for SDT.

[0042] In one possible implementation, the non-RRC connection state is an RRC inactive state; after the second timer times out, the terminal is in the RRC inactive state.

[0043] In one possible implementation, the first preset condition further includes the terminal receiving SIB1 of the first serving cell, and the first serving cell belonging to the configured RNA; before setting the first variable to the first value when the first preset condition is met, the method further includes: when the second timer is running, if cell reselection occurs, stopping the second timer, the second timer being started when the terminal initiates the RRC connection recovery process for SDT; receiving SIB1 of the first serving cell, the first serving cell being the serving cell after the terminal has undergone cell reselection.

[0044] In one possible implementation, after setting the first variable to the first value, the method further includes: if the access ban is mitigated and the non-access NAS layer does not request the RRC layer to perform RRC connection restoration, and if the first variable is the first value, performing the RRC connection restoration process for RNAU.

[0045] In one possible implementation, the non-RRC connection state is an RRC inactive state.

[0046] In this application, if the first timer times out while the second timer is running (i.e., during SDT), the terminal will not execute RNAU, nor will it set the first variable to the first value, thereby avoiding affecting the currently running SDT process. When the SDT process ends abnormally (e.g., the second timer stops or times out), and the first timer has not run, the terminal can set the first variable to the first value so that RNAU can be executed normally subsequently.

[0047] Thirdly, embodiments of this application provide another method for controlling transmission, applied to a terminal in a non-RRC connection state. The method includes: starting a first timer; initiating an RRC connection recovery process for SDT; during the RRC connection recovery process for SDT, the lower layer indicates first information to the upper layer, the first information indicating that the RRC connection recovery process for SDT is successful; and stopping the first timer based on the first information.

[0048] In some embodiments, the terminal starts the first timer when it receives an RRC release message that includes the duration of the first timer. For example, the first timer is T380.

[0049] In this application, when the terminal performs the SDT process, the first timer can be stopped, thereby preventing the first timer from timeout and triggering RNAU. During SDT, the network device can obtain the RNA where the terminal is located. Not triggering RNAU not only does not affect the network device's ability to obtain the terminal's status, but also avoids affecting the transmission of small packet data during the SDT process.

[0050] In one possible implementation, the initiation of the RRC connection recovery process for SDT includes: the terminal sending an RRC request message to the network device; the terminal's underlying layer receiving a first response message sent by the network device in response to the RRC request message; and the underlying layer indicating first information to the upper layer, including: based on the first response message, the underlying layer indicating the first information to the upper layer.

[0051] In one possible implementation, the RRC connection recovery process for SDT includes: the terminal sending an RRC request message to the network device during random access; the lower layer indicating first information to the upper layer includes: the Media Access Control (MAC) layer indicating first information to the RRC layer, the first information indicating successful contention resolution; and stopping the first timer based on the first information includes: the RRC layer receiving the first information indicated by the MAC layer and stopping the first timer.

[0052] In one possible implementation, the terminal sends an RRC request message to the network device, including: the terminal sending the RRC request message to the network device during a random access process, wherein the first response message indicates that the contention was successfully resolved.

[0053] For example, the first response message is a contention resolution message.

[0054] In one possible implementation, the RRC connection recovery process for SDT includes: the terminal sending an RRC request message to the network device based on pre-configured uplink resources; the first information indicating that the RRC request message was successfully sent.

[0055] In one possible implementation, the lower layer indicating first information to the upper layer includes: the Media Access Control (MAC) layer indicating first information to the RRC layer; stopping the first timer based on the first information includes: the RRC layer receiving the first information indicated by the MAC layer and stopping the first timer; or, the lower layer indicating first information to the upper layer includes: the physical layer indicating first information to the RRC layer; stopping the first timer based on the first information includes: the RRC layer receiving the first information indicated by the physical layer and stopping the first timer; or, before the lower layer indicates first information to the upper layer, the method further includes: the physical layer indicating second information to the MAC layer, the second information indicating that the RRC request message was successfully sent; the lower layer indicating first information to the upper layer includes: the MAC layer receiving the second information indicated by the physical layer and indicating first information to the RRC layer; stopping the first timer based on the first information includes: the RRC layer receiving the first information indicated by the MAC layer and stopping the first timer.

[0056] In one possible implementation, the terminal sending an RRC request message to the network device includes: the terminal sending the RRC request message to the network device based on pre-configured uplink resources, and a first response message indicating that the RRC request message was successfully sent.

[0057] In one possible implementation, initiating the RRC connection recovery process for SDT includes: initiating the RRC connection recovery process for SDT and starting a second timer.

[0058] In one possible implementation, after stopping the first timer, the method further includes: if an RRC rejection message is received while the second timer is running, stopping the second timer; if the first timer is not running, setting a first variable to a first value, wherein the first variable being the first value indicates an pending RNA update process.

[0059] In this application, if the first timer is stopped during the SDT process, the terminal can set the first variable to the first value when the SDT process ends abnormally (such as when the second timer stops or times out), so that RNAU can continue to be triggered subsequently, ensuring the normal execution of RNAU.

[0060] In one possible implementation, after stopping the first timer, the method further includes: if an RRC rejection message is received while the second timer is running, stopping the second timer; if the first timer is not running, executing the Radio Resource Control (RRC) connection recovery process for RNAU.

[0061] In this application, if the first timer is stopped during the SDT process, the terminal can execute RNAU again when the SDT process ends abnormally (such as when the second timer stops or times out), thus ensuring the normal execution of RNAU.

[0062] In one possible implementation, after stopping the first timer, the method further includes: if an RRC rejection message is received while the second timer is running, stopping the second timer; if the first timer is not running, starting a third timer; and when the third timer times out, if the second timer is not running, executing the RRC connection recovery process for RNAU.

[0063] In one possible implementation, the duration of the third timer is the same as the duration of the first timer.

[0064] In one possible implementation, the duration of the third timer is different from that of the first timer.

[0065] In one possible implementation, the non-Radio Resource Control (RRC) connection state is an RRC inactive state; after receiving an RRC rejection message, the terminal is in the RRC inactive state.

[0066] In this application, if the first timer is stopped during the SDT process, the terminal can start the third timer when the SDT process ends abnormally (such as when the second timer stops or times out). When the third timer times out and the second timer is not running, the RNAU is executed to ensure the normal execution of the RNAU.

[0067] In one possible implementation, the method further includes: when the second timer times out, if the first timer has not run, setting a first variable to a first value, wherein the first variable being the first value indicates an pending RNA update process.

[0068] In one possible implementation, the method further includes: when the second timer times out, if the first timer has not run, executing the Radio Resource Control (RRC) connection recovery process for RNAU.

[0069] In one possible implementation, the method further includes: when the second timer times out, if the first timer has not run, starting a third timer; when the third timer times out, if the second timer has not run, executing the RRC connection recovery process for RNAU.

[0070] In one possible implementation, the duration of the third timer is the same as the duration of the first timer.

[0071] In one possible implementation, the duration of the third timer is different from that of the first timer.

[0072] In one possible implementation, the non-radio resource control (RRC) connected state is an RRC inactive state; after the first timer expires, the terminal is in the RRC inactive state.

[0073] In one possible implementation, the method further includes: stopping the second timer if a cell reselection occurs while the second timer is running; receiving SIB1 of a first serving cell, wherein the first serving cell is the serving cell after the cell reselection of the terminal; and when the SIB1 of the first serving cell is received, if the first serving cell belongs to a configured RNA and the first timer is not running, setting a first variable to a first value, wherein the first variable and the first value indicate an pending RNA update process.

[0074] In one possible implementation, the method further includes: if cell reselection occurs while the second timer is running, stopping the second timer; receiving SIB1 of a first serving cell, wherein the first serving cell is the serving cell after the cell reselection of the terminal; and when the SIB1 of the first serving cell is received, if the first serving cell belongs to the configured RNA and the first timer is not running, executing the Radio Resource Control (RRC) connection recovery process for RNAU.

[0075] In one possible implementation, the method further includes: when the second timer is running, if a cell reselection occurs, stopping the second timer; receiving SIB1 of a first serving cell, wherein the first serving cell is the serving cell after the cell reselection of the terminal; when the SIB1 of the first serving cell is received, if the first serving cell belongs to the configured RNA and the first timer is not running, starting a third timer; when the third timer times out, if the second timer is not running, executing the RRC connection recovery process for the RNAU.

[0076] In one possible implementation, the duration of the third timer is the same as that of the second timer.

[0077] In one possible implementation, the duration of the third timer is different from that of the second timer.

[0078] In one possible implementation, the non-radio resource control (RRC) connected state is an RRC inactive state; after the terminal undergoes cell reselection, the terminal is in the RRC inactive state.

[0079] In one possible implementation, after setting the first variable to the first value, the method further includes: if the access ban is mitigated and the non-access NAS layer does not request the RRC layer to perform RRC connection restoration, and if the first variable is the first value, performing the RRC connection restoration process for RNAU.

[0080] In one possible implementation, the non-RRC connection state is an RRC inactive state.

[0081] Fourthly, embodiments of this application provide a terminal, including a transceiver, a processor, and a memory; the memory is used to store computer program code, the computer program code including computer instructions, and the processor calls the computer instructions to cause the user equipment to execute the control transmission method provided by the first to third aspects of the embodiments of this application, and any implementation of the first to third aspects.

[0082] Fifthly, embodiments of this application provide a communication device, which can be a terminal or a chip in a terminal. The communication device includes a processing unit, which is used to execute the control transmission method provided by the first to third aspects of the embodiments of this application and any implementation of the first to third aspects.

[0083] In a sixth aspect, embodiments of this application provide a computer storage medium storing a computer program, the computer program including program instructions, which, when executed by a processor, are used to perform the control transmission method provided by the first to third aspects of embodiments of this application, and any implementation thereof.

[0084] In a seventh aspect, embodiments of this application provide a computer program product that, when run on a communication device, causes the communication device to execute the control transmission method provided by the first to third aspects of the embodiments of this application, and any implementation thereof.

[0085] Eighthly, embodiments of this application provide an electronic device that includes the methods or apparatus described in any embodiment of this application. The electronic device is, for example, a chip. Attached Figure Description

[0086] The accompanying drawings used in the embodiments of this application are described below.

[0087] Figure 1 This is a schematic diagram of the architecture of a communication system provided in an embodiment of this application;

[0088] Figure 2 This is a schematic diagram of the communication protocol stack architecture for the user plane of a new type of wireless access (NR).

[0089] Figure 3 This is a schematic diagram of the communication protocol stack architecture of the control plane of NR;

[0090] Figure 4 This is a schematic diagram illustrating the transition of Radio Resource Control (RRC) state in a User Equipment (UE).

[0091] Figures 5-10 This is a schematic diagram of some small packet data transmission SDT provided in the embodiments of this application;

[0092] Figure 11 This is a flowchart illustrating a method for controlling transmission provided in an embodiment of this application;

[0093] Figure 12 This is a timing diagram provided in an embodiment of this application;

[0094] Figures 13-17 This is a flowchart illustrating some of the control transmission methods provided in the embodiments of this application;

[0095] Figure 18 This is yet another timing diagram provided in the embodiments of this application;

[0096] Figure 19This is a flowchart illustrating another method for controlling transmission provided in an embodiment of this application. Detailed Implementation

[0097] The technical solutions in the embodiments of this application will be clearly and thoroughly described below with reference to the accompanying drawings. The terminology used in the implementation section of the embodiments of this application is only used to explain the specific embodiments of this application and is not intended to limit this application.

[0098] First, the relevant devices and communication systems involved in this application will be introduced.

[0099] In this application embodiment, the network device can be a device used to send or receive information. In some embodiments, the network device is an access network device, such as, but not limited to: a base station, user equipment (UE), a radio access point (AP), a transmission and receiver point (TRP), a relay device, or other network devices with base station functions. A base station is a device deployed in a radio access network (RAN) to provide wireless communication functions. The name of a base station may vary in different radio access systems, for example, but not limited to: a base transceiver station (BTS) in Global System for Mobile Communications (GSM) or Code Division Multiple Access (CDMA), a node B (NB) in Wideband Code Division Multiple Access (WCDMA), an evolved node B (eNodeB) in Long Term Evolution (LTE), or a next-generation base station (gnode B, gNB) in 5th generation mobile networks (5G), i.e., new radio access (NR), or a base station in other future network systems.

[0100] In this application, the terminal can be a device with wireless communication capabilities. In some embodiments, the terminal is a UE (User Equipment), and in others, it may also be referred to as a mobile station, access terminal, user agent, etc. Exemplarily, the terminal is a handheld device, wearable device, computing device, portable device, or vehicle-mounted device. Specifically, the terminal is a cellular phone, smartphone, smart glasses, laptop, personal digital assistant, or cordless phone. The following embodiments use a UE as an example for illustration.

[0101] Please see Figure 1 , Figure 1 This is a schematic diagram of the architecture of a communication system provided in an embodiment of this application. The communication system may be, but is not limited to, GSM, CDMA, wideband code division multiple access (WCDMA), time-division code division multiple access (TD-SCDMA), universal mobile telecommunications system (UMTS), LTE, NR, or other future network systems.

[0102] like Figure 1 As shown, the communication system may include a core network 110, network devices 120, and UEs 130. The core network 110 can connect to at least one network device 120, and the network device 120 can provide wireless communication services to at least one UE 130. The UE 130 can connect to at least one network device 120 via an air interface. The core network 110 is a key control node in this communication system, primarily responsible for signaling processing functions, such as, but not limited to, implementing access control, mobility management, and session management. In some embodiments, the network device 120 is a base station. In NR, the core network 110 may be referred to as the 5G Core Network (5GCore, 5GC) 110, and the network device 120 may be referred to as gNB 120. In some embodiments, at least one base station can constitute a next-generation-radio access network (NG-RAN) node. The NG-RAN node may include at least one gNB 120 connected to the 5GC 110 via an NG interface, and at least one gNB 120 in the NG-RAN node can connect and communicate via an Xn-C interface. The UE130 can connect to the gNB120 via the Uu interface.

[0103] Core network 110 can send downlink data to UE 130 through network device 120, and UE 130 can also send uplink data to core network 110 through connected network device 120. It should be noted that... Figure 1 The form and quantity of the core network 110, network device 120 and UE 130 shown are for illustrative purposes only, and are not limited in this application embodiment.

[0104] For ease of understanding, the embodiments of this application mainly use LTE and / or NR as the application communication system, network equipment as the base station, and an NG-RAN including at least one base station as an example for illustration.

[0105] The following section provides an example of NR's communication protocol stack.

[0106] Please see Figure 2 , Figure 2 This is a schematic diagram of the architecture of a user plane protocol stack for NR. This user plane protocol stack can include a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0107] Please see Figure 3 , Figure 3 This is a schematic diagram of the architecture of a control plane protocol stack for NR. This control plane protocol stack may include the PHY layer, MAC layer, RLC layer, PDCP layer, radio resource control (RRC) layer, and non-access stratum (NAS).

[0108] Compared to the LTE user plane protocol stack, the NR user plane protocol stack adds the SDAP layer, but the architecture of other layers is the same, and the specific descriptions are similar. LTE is more mature, so we will not go into details.

[0109] like Figure 2 and Figure 3As shown, the lower layer of the PDCP layer includes the RLC layer. The PDCP layer can process RRC messages on the control plane and perform IP header compression to reduce the number of bits transmitted on the radio interface. The PDCP layer is also responsible for control plane encryption and data integrity protection. At the receiving end, the PDCP layer performs corresponding decryption and decompression operations. One PDCP entity can be configured for each radio bearer. The RLC layer is responsible for segmentation / concatenation, retransmission control, and duplicate detection, and provides services to the PDCP layer. One RLC entity can be configured for each radio bearer. The MAC layer controls the multiplexing of logical channels, retransmission of hybrid automatic repeat requests, and uplink and downlink scheduling. The MAC layer provides services to the RLC layer in the form of logical channels. The PHY layer manages encoding / decoding, modulation / demodulation, multi-antenna mapping, and other physical layer functions. The PHY layer provides services to the MAC layer in the form of transport channels.

[0110] like Figure 2 and Figure 3 As shown, the MAC layer can provide services to higher layers (such as the RLC layer) via logical channels (LCH). Based on the type of information transmitted, logical channels can be classified into control channels for transmitting control information in the control plane and traffic channels for transmitting user data in the user plane. Control channels may include, but are not limited to, common control channels (CCCH) and dedicated control channels (DCCH). Traffic channels may include, but are not limited to, dedicated traffic channels (DTCH). The CCCH can always exist; UEs without an RRC connection to the RAN node can also use the CCCH to transmit information. The DCCH can be used to transmit dedicated control information between the UE and the RAN node. The DTCH can be used to transmit user data between the UE and the RAN node. Typically, the DCCH and DTCH do not always exist; they can only be used for communication between the UE and the base station after the base station connected to the UE restores the UE context. The UE context includes, but is not limited to, the terminal's identifier, radio bearer (RB) related configurations, integrity protection and encryption security-related configurations, and quality of service-related configurations.

[0111] An RB can be a set of connection formats between a UE and a RAN node, and can include the configuration of physical channels, transport channels, and logical channels. RBs can be divided into signaling radio bearers (SRBs) used to transmit control information in the control plane and data radio bearers (DRBs) used to transmit user data in the user plane. A DRB can include a PDCP layer entity (PDCP entity), an RLC layer entity (RLC entity), and a logical channel.

[0112] like Figure 3 As shown, the RRC layer can be used to transmit RRC messages between the UE and the base station. For example, but not limited to, the RRC Resume Request in NR can be used by the UE to request the resumption of a suspended RRC connection in order to transmit data with the base station. The RRC layer belongs to the access stratum (AS).

[0113] For the RRC layer, there are currently three UE RRC states: RRC IDLE, RRC INACTIVE, and RRC CONNECTED. The operations performed by the UE differ depending on the RRC state. Details of these three states and their transition processes can be found below. Figure 4 Examples.

[0114] like Figure 4As shown, when the UE is in RRC CONNECTED state, an RRC connection is established between the UE and the base station. In some embodiments, when the UE is in RRC CONNECTED state, a user plane and control plane connection can be established between the 5GC and NG-RAN. The NG-RAN and the UE can retain the UE context at the AS layer. The NG-RAN can obtain the cell to which the UE belongs. The UE can send or receive unicast data. The network (e.g., NG-RAN) can control the mobility of the UE. For example, the UE can measure the channel with the base station and report the measurement results to the base station. The base station can determine whether to switch the cell to which the UE belongs based on the measurement results. In other words, in RRC CONNECTED state, the UE and the base station can not only transmit data normally, but the base station can also manage the UE. In some embodiments, if the UE in RRC CONNECTED state wants to send uplink data to the base station, it needs to synchronize with the base station according to the timing advance (TA). If the UE in RRC CONNECTED state does not obtain uplink synchronization, the UE can initiate random access (RA) to the base station. In this configuration, the UE maintains uplink synchronization while its timing advance timer (TAT) is running. When the UE's TAT ​​times out, uplink synchronization fails. If the UE needs to retransmit uplink data to the base station, it needs to initiate an Access Registry (RA) to obtain a new timing agreement (TA). In some embodiments, when the UE is in the RRC CONNECTED state, the base station can allocate configured grant (CG) resources to the UE. When the UE has data transmission requirements, it can use CG resources to send uplink data to the base station. In some embodiments, the base station can configure CG resources for the UE via RRC messages, and the configuration information may include time-frequency location and period. Compared to dynamically scheduling transmission resources, this method of transmitting data via CG resources can reduce signaling overhead and transmission latency.

[0115] When there are no uplink resources but uplink data to be sent to the base station, a UE in the RRC CONNECTED state can trigger a buffer status reporting (BSR) to request the base station to allocate uplink resources. The BSR indicates the amount of data currently to be transmitted in the UE's data buffer. This amount can vary at different times. For example, if the UE is a smartphone, the user can send messages to other users through social applications installed on the UE. However, the type and number of messages sent by the user can differ at different times; sometimes the message may be just a text message, and sometimes it may include multiple videos. Therefore, the size of the BSR sent by the UE to the base station can also vary at different times. The resources used by the UE to send BSRs to the base station (referred to as BSR resources) can be dynamically allocated to the UE by the base station.

[0116] When the UE is in RRC IDLE state, no RRC connection is established between the UE and the base station. In some embodiments, when the UE is in RRC IDLE state, the UE can select a public lands mobile network (PLMN), receive system information broadcast by the base station, perform cell re-selection, initiate paging for downlink transmission by the 5GC, and perform discontinuous reception (DRX) configured by the NAS layer for core network paging, etc.

[0117] The RRC INACTIVE state is a newly added RRC state in NR. In some embodiments, for UEs with infrequent data transmission, the base station typically keeps the UE in the RRC INACTIVE state. In some embodiments, when the UE is in the RRC INACTIVE state, the UE can select a PLMN, receive system information broadcast by the base station, undergo cell reselection, initiate paging by the NG-RAN, and manage the RAN-based Notification Area (RNA) by the NG-RAN. For example, the UE triggers an RNA update (RNAU) to notify the base station of the RNA in which the UE is currently located. The NG-RAN configures the DRX for RAN paging, and user plane and control plane connections for the UE can be established between the 5GC and the NG-RAN. The NG-RAN and the UE can retain the UE context at the AS layer, and the NG-RAN can obtain the RNA in which the UE is located. In some embodiments, after the UE establishes an RRC connection with the base station, the UE enters the RRCCONNECTED state. If the UE in the RRC CONNECTED state has no data transmission needs with the base station within a preset time period, the base station can instruct the UE to enter the RRC_INACTIVE state. For example, the base station can send an RRC release (RRCRelease with suspend indication) message to the UE. After receiving the RRCelease with suspend indication message, the UE retains its own context and enters the RRCINACTIVE state.

[0118] Among them, the three states mentioned above in the RRC layer can be transformed into each other, such as Figure 4As shown, in some embodiments, when a UE is in RRC IDLE or RRC INACTIVE state (collectively referred to as non-RRC connected state), it can execute an RRC connection establishment procedure or an RRC connection recovery procedure if data transmission is required. For example, a UE in RRC IDLE state can send an RRC setup request message to the base station, and then receive an RRC setup message from the base station. After receiving the RRC setup message, the UE can establish an RRC connection with the base station and enter the RRC CONNECTED state. For example, a UE in RRC INACTIVE state can send an RRC Resume Request message to the base station, and then receive an RRC recovery message from the base station. After receiving the RRC Resume message, the UE can enter the RRC CONNECTED state. In other embodiments, when a UE is in non-RRC connected state, it can also execute an RRC connection establishment procedure or an RRC connection recovery procedure in response to a paging message from the base station. For example, the core network can instruct the base station to send a paging message to the UE when data is to be transmitted to the UE.

[0119] In some embodiments, the UE can enter the RRC INACTIVE or RRC IDLE state from the RRC CONNECTED state under the instruction of the base station. In some embodiments, when the UE does not need to perform data transmission subsequently, the base station can release the UE to allow it to enter the RRC INACTIVE or RRC IDLE state, as illustrated in the following examples.

[0120] Example 1: Under the instruction of the base station, the UE transitions from the RRC CONNECTED state to the RRC INACTIVE state. Specifically, the base station can send a release message with a suspend indication, such as `RRCRelease with suspend indication`, to the UE to enter the RRC INACTIVE state. At this time, the RRC connection between the UE and the base station is suspended, but at least one RAN node retains the UE's UE context.

[0121] Example 2: Under the instruction of the base station, the UE enters the RRC IDLE state from the RRC CONNECTED state. Specifically, the base station can send a release message to the UE, such as an RRC release message, to cause the UE to enter the RRC IDLE state. At this time, the RRC connection between the UE and the base station will be stopped, and the RAN node will delete the UE context.

[0122] In some embodiments, the UE can also enter the RRC IDLE state from the RRC INACTIVE state under the instruction of the base station. For example, after the UE in the RRC INACTIVE state sends an RRC connection restoration request, the base station can release the UE to allow it to enter the RRC IDLE state. Understandably, the UE can enter the RRC CONNECTED state from the RRC INACTIVE state faster than from the RRC IDLE state.

[0123] In some embodiments, when a UE is in RRC IDLE or RRC INACTIVE state, if data transmission is required, it can execute an RRC connection establishment procedure or an RRC connection recovery procedure to request entry into the RRCCONNECTED state for data transmission. If the UE in RRC IDLE or RRC INACTIVE state does not have the resources to send an RRCSetupRequest or RRCResumeRequest message, the UE needs to initiate a random access (RA) procedure. The RA procedure will be described exemplarily below.

[0124] In some embodiments, the UE can obtain the current cell's RA configuration from system information broadcast by the base station. For example, this configuration includes available random access preambles and RA resources for transmitting the random access preambles. For instance, the RA resources for transmitting the random access preambles are the time-frequency resources for the UE to transmit the random access preambles, also known as random access occasions (RO). In some embodiments, the RA may include 4-step random access (4-step RA) and 2-step random access (2-step RA). The base station can broadcast the RA configurations corresponding to 4-step RA and 2-step RA in system messages, or it can broadcast only the RA configurations corresponding to 4-step RA in system messages, or it can broadcast only the RA configurations corresponding to 2-step RA in system messages.

[0125] In some embodiments, the base station can broadcast the RA configuration corresponding to 4-step RA and the RA configuration corresponding to 2-step RA in system messages. When the UE has not configured contention-free random access (CFRA) resources, the UE can determine whether to initiate 4-step RA or 2-step RA based on the relative magnitude of the currently measured reference signal receiving power (RSRP) and a preset RSRP threshold. For example, if the currently measured RSRP is greater than or equal to the preset RSRP threshold, the UE can initiate 2-step RA. If the currently measured RSRP is less than the preset RSRP threshold, the UE can initiate 4-step RA.

[0126] In the third step of the 4-step RA, the message sent by the UE to the base station can be called message 3, or simply msg3. In the first step of the 2-step RA, the message sent by the UE to the base station can be called message A, or simply msgA. In some embodiments, msg3 or msgA may include an RRC message. This RRC message may differ depending on the UE's RRC state and the service scenario. For example, when a UE in the RRC INACTIVE state has data to send to the base station, the msg3 sent by the UE to the base station may include an RRCResumeRequest message, requesting the resumption of the suspended RRC connection and entry into the RRCCONNECTED state to transmit data with the base station.

[0127] Under normal circumstances, a UE in a non-RRC connected state sends uplink data to the base station, or receives a paging message from the base station. This paging message indicates that downlink data is available for the UE, requiring the UE to re-establish or restore the RRC connection and enter the RRC CONNECTED state. In the RRC CONNECTED state, the UE then transmits data with the base station. However, this method is more suitable for situations where the amount of data transmitted between the UE and the base station is large. If the transmitted data packets are very small (small data), the signaling required for the UE to switch states can be even greater than that of small data packets, leading to unnecessary power consumption and signaling overhead for the UE. Therefore, it is necessary to transmit small data packets to the base station when the UE is in a non-RRC connected state. For example, when a UE in the RRC INACTIVE state needs to transmit uplink small data packets, it can transmit the uplink small data packets to the base station.

[0128] In this embodiment, small packet data may include, but is not limited to, data packets with a data size less than a preset threshold (e.g., the size of a transport block indicated by a base station), data packets labeled as small packet data, and data packets whose data type is small packet data. Non-small packet data packets may be referred to as large packet data, and may include, but is not limited to, data packets with a data size greater than or equal to a preset threshold, data packets labeled as large packet data, and data packets whose data type is large packet data. The aforementioned data labels and / or data types can be negotiated jointly by the UE and the network device. For example, data labels may include both large packet data and small packet data. For example, data with a heartbeat data type is small packet data, while data with a file, video, or audio data type is large packet data. Exemplarily, small packet data may be instant messaging messages from the UE's application (APP), heartbeat packets from the APP, or push messages from the APP; small packet data may be periodic data from wearable devices; or small packet data may be business data from Internet of Things (IoT) devices.

[0129] In some embodiments, transmitting small data packets to the base station when the UE is in a non-RRC connected state may include the UE transmitting small data during the RA process without entering the RRC CONNECTED state before transmitting small data. This transmission process can be called RA-based small data transmission (SDT), or RA-SDT for short. In some embodiments, RA may include 4-step RA and 2-step RA, and SDT may include 4-step RA-based SDT (4-step SDT for short) and 2-step RA-based SDT (2-step SDT for short). An example of the 4-step SDT process can be found below. Figure 5 and Figure 6 An example of the 2-step SDT process can be found below. Figure 7 and Figure 8 The implementation of RA-SDT is similar to that of RA. For example, the UE can obtain the RA-SDT configuration from the system information broadcast by the base station. The UE can determine whether to initiate 4-step SDT or 2-step SDT based on the relative size of the currently measured RSRP and the preset RSRP threshold.

[0130] In other embodiments, transmitting small data packets to the base station when the UE is in a non-RRC connected state may further include the UE transmitting small data through pre-allocated CG resources or pre-configured uplink resources (PUR), without needing to enter the RRC connected state before transmitting small data. This transmission process can be called CG-based SDT, or CG-SDT for short. A specific example of the process can be found below. Figure 9 and Figure 10 .

[0131] In some embodiments, SDT has multiple different application scenarios, and different implementations of SDT can be used depending on the application scenario, such as RA-SDT or CG-SDT. Specific examples are shown below:

[0132] Example 1: In CG-SDT, the resources (such as CG resources or PURs) indicated by the CG-SDT configuration are issued to the UE by the base station through dedicated control signaling. Therefore, the CG-SDT configuration is applicable to UEs in the cells covered by the base station. The CG-SDT configuration provided in one cell cannot be reused by UEs in another cell. If the UE moves to the coverage area of ​​other network devices, the resources indicated by the CG-SDT configuration can no longer be used. Based on this characteristic, it can be applied to the following scenarios: For IoT applications, UE mobility is limited, and they usually establish all connections in the same cell to send data, and rarely change cells. Therefore, UEs in the IoT field can give priority to using CG-SDT.

[0133] Example 2: RA-SDT Configuration. The RA configuration related to RA can be provided by system information sent by the base station. Whenever the UE reselects a new cell, the UE can read and apply the configuration broadcast by the system information. Based on this characteristic, it can be applied to scenarios such as: For applications like instant messaging on smartphones, the UE is highly mobile and may move from the coverage area of ​​one base station to the coverage area of ​​another. If the UE moves from the coverage area of ​​base station A to the coverage area of ​​base station B, and is within the coverage area of ​​base station B, using the resources indicated by the CG-SDT configuration sent by base station A before the move for SDT will result in data transmission failure. Since the resources for sending the random access preamble in RA-SDT are broadcast by the base station in real time, RA-SDT can be preferentially used for highly mobile UEs.

[0134] Of course, whether the UE adopts CG-SDT or RA-SDT is not limited by the scenario, and the method of SDT can be determined based on the UE's implementation.

[0135] For example, since the resources for CG-SDT are specifically configured by the base station for the UE, the success rate of CG-SDT is relatively high. RA-SDT random access resources are broadcast by network devices. Any UE that can receive the broadcast message can initiate RA-SDT on the random access resources. Multiple UEs will compete for the resources, which may lead to competition failure. Therefore, the success rate of RA-SDT is not as high as that of CG-SDT, and CG-SDT is more likely to be effective than RA-SDT. Typically, the UE prefers CG-SDT, but certain conditions must be met for the UE to choose CG-SDT. If these conditions are not met, the UE can choose RA-SDT. For example, whether the resources indicated by the CG-SDT configuration are within the coverage area of ​​the normal uplink (NUL) carrier or supplementary uplink (SUL) carrier the UE is currently on. If the resources indicated by the CG-SDT configuration are available, and there are valid resources among those indicated by the CG-SDT configuration, the UE can choose CG-SDT; otherwise, it will choose RA-SDT.

[0136] Understandably, the base station can first configure a Data Relay (DRB) for the UE to carry data, and the UE can only transmit data after restoring its context (including the DRB). In some embodiments, the DRB configured by the base station for the UE may include a DRB for carrying small packet data (SDT DRB) and a DRB for carrying large packet data (non-SDT DRB). The UE can only initiate SDT when small packet data carried by the SDT DRB arrives; if large packet data carried by the non-SDT DRB arrives, the UE cannot initiate SDT. When the UE initiates SDT, it needs to restore the UE context, which may include the SDT DRB.

[0137] In some embodiments, the state of SDT can be determined by the state of the first timer, which can be represented as T3XX, where X is a non-negative integer less than 10. The first timer can be called the SDT failure detection timer, and the first timer can be a timer of the RRC layer.

[0138] In some embodiments, when the UE initiates an RRC connection recovery procedure for SDT, a first timer may be started. In some embodiments, when the UE initiates an RRC connection recovery procedure for SDT, the UE initializes the RRC connection recovery procedure for SDT, and the first timer may be started. In other embodiments, when the UE initiates an RRC connection recovery procedure for SDT, the UE sends an RRC request message to the base station to initiate the RRC connection recovery procedure for SDT, and the first timer may be started. In some embodiments, the condition for starting the first timer includes: initializing the RRC connection recovery procedure for SDT. In other embodiments, the condition for starting the first timer includes: sending an RRC request message to initiate the RRC connection recovery procedure for SDT. For example, the RRC request message is an RRC request message in msg3 or msgA sent by the UE to the base station based on RA-SDT; or, for example, the RRC request message is an RRC request message sent by the UE to the base station based on CG-SDT.

[0139] In some embodiments, the UE may stop the first timer upon receiving an RRC response message or upon a cell reselection. In some embodiments, the conditions for stopping the first timer may include receiving an RRC response message or a cell reselection. The RRC response message may be, for example, an RRCResume message, an RRCSetup message, an RRCRelease message, an RRCRelease with suspend indication message, an RRCReject message, or other RRC messages with the same function but not standardized by the 3rd Generation Partnership Project (3GPP). If the UE receives an RRCRelease message, an RRCRelease with suspend indication message, or other RRC messages with the same function but not standardized by 3GPP, the UE may consider the SDT successful and stop the first timer. If the UE receives an RRCResume message, an RRCSetup message, or other RRC messages with the same function but not standardized by 3GPP, the UE may consider the SDT successful and stop the first timer, or the UE may consider the SDT successful, enter the RRCCONNECTED state, continue data transmission, and stop the first timer. If the UE receives an RRCReject message or other RRC messages with the same function but not standardized by 3GPP, the UE can consider this SDT to have failed and stop the first timer.

[0140] In some embodiments, if the UE does not receive any response message from the base station during the period from the start of the first timer to its timeout, such as a contention resolution message, an RRC response message, or other response message, the UE may consider the SDT to have failed and automatically terminate the SDT. Understandably, the first timer can prevent the base station from failing to respond to the UE for an extended period after the UE sends a request message or data to the base station.

[0141] The following example illustrates the transmission process of SDT.

[0142] Please see Figure 5 , Figure 5 An exemplary flowchart of a 4-step SDT process in the user plane is shown. Figure 5 The process shown may include, but is not limited to, the following steps:

[0143] S111: The UE sends a random access preamble to the base station.

[0144] In some embodiments, the base station may send a broadcast message to the UE, the broadcast message including first resource configuration information, which indicates random access resources for sending a random access preamble. Optionally, the first resource configuration information may specifically indicate a first random access resource for initiating normal random access; alternatively, the first resource configuration information may specifically indicate a second random access resource for sending a random access preamble during RA-SDT. The random access preamble may be generated by the UE according to specific rules, but the base station can recognize the random access preamble generated by the UE.

[0145] In some embodiments, the random access preamble for the UE to perform RA-SDT transmission can be different from the random access preamble for the UE to initiate normal RA without performing RA-SDT. That is, the base station can use different random access preambles to distinguish the UE's intent, such as whether the UE's intent is to perform RA-SDT or to initiate RA.

[0146] In other embodiments, the random access preamble for the UE to perform RA-SDT transmission can be the same as the random access preamble for the UE to initiate normal RA without performing RA-SDT.

[0147] In some embodiments, if the first resource configuration information specifically indicates a first random access resource for initiating normal random access and a second random access resource for transmitting a random access preamble during RA-SDT, then the UE can transmit a random access preamble on different random access resources based on different intentions. In this way, the base station can distinguish the UE's intentions by utilizing different resources that receive the random access preamble. For example, if the UE intends to initiate RA and transmits a random access preamble on the first random access resource, the base station can determine that the UE's intention is to initiate RA when it receives the random access preamble through the first random access resource. If the UE intends to perform RA-SDT and transmits a random access preamble on the second random access resource, the base station can determine that the UE's intention is to perform RA-SDT when it receives the random access preamble through the second random access resource.

[0148] In other embodiments, the random access resources for the UE to send a random access preamble for RA-SDT can be the same as the random access resources for the UE to initiate a normal RA without RA-SDT.

[0149] S112: In response to the random access preamble, the base station sends a random access response (RAR) to the UE.

[0150] Specifically, after the UE sends a random access preamble to the base station, it can listen to the physical downlink control channel (PDCCH) within the RAR time window to receive the RAR sent by the base station. If the UE does not receive the RAR sent by the base station within the RAR time window, the UE can determine that the RA has failed. The RAR is used to schedule uplink resources (uplink grant, UL grant) for the UE so that the UE can send msg3 (including the RRC request message in S113) on the resources scheduled by the RAR.

[0151] In some embodiments, the RAR may also include at least one of a temporary cell radio network temporary identifier (TC-RNTI) and a timing advance (TA). The TA is used by the UE to obtain uplink synchronization information.

[0152] S113: The UE sends uplink small packet data and RRC request message to the base station on the resources allocated by RAR.

[0153] In some embodiments, the RRC request message may carry intent information, which indicates the UE's intent in sending the RRC request message, such as the UE's intent to perform RA-SDT or to initiate RA. For example, if the random access preamble sent by the UE to initiate RA-SDT is the same as the random access preamble sent by the UE to initiate normal RA without performing RA-SDT, or if the random access resources sent by the UE to initiate RA-SDT are the same as the random access resources transmitted by the UE to initiate normal RA without performing RA-SDT, the RRC request message sent by the UE to perform RA-SDT may carry intent information, which indicates the UE's intent to initiate RA-SDT, rather than the intent to initiate normal RA.

[0154] In other embodiments, the UE may send a BSR when sending msg3 to the base station. The base station can obtain the UE's intent through the BSR sent by the UE, such as whether the UE's intent is to perform RA-SDT or to initiate RA. For example, the random access preamble sent by the UE to perform RA-SDT is the same as the random access preamble sent by the UE to initiate normal RA without performing RA-SDT. The random access resources used by the UE to send the random access preamble to perform RA-SDT can also be the same as the random access resources used by the UE to initiate normal RA without performing RA-SDT. If the UE wants to perform RA-SDT, it can send a BSR when sending msg3 to the base station. This BSR is used to indicate the amount of data in the small packet. The base station can obtain the UE's intent to initiate RA-SDT, rather than to initiate normal RA, through the received BSR.

[0155] In some embodiments, the RRC request message in msg3 may differ depending on the UE's RRC state and service scenario. For example, an RRC request message sent by a UE in RRC IDLE state (optionally, the UE may store UE context such as configuration information for obtaining the key used to encrypt the aforementioned uplink small packet data, or the terminal may not store its context) may include an RRC Connection Request message, an RRC Connection Resume Request message, an RRC Early Data Request message, an RRC Resume Request message, an RRC Resume Request1 message, an RRC Setup Request message, or other RRC messages with the same function but not standardized by 3GPP. An RRC request message sent by a UE in RRC INACTIVE state may be an RRC Connection Request message, an RRC Connection Resume Request message, an RRC Resume Data Request message, an RRC Resume Request message, an RRC Resume Request1 message, an RRC Setup Request message, or other RRC messages with the same function but not standardized by 3GPP.

[0156] In some embodiments, the UE may send uplink small packet data and an RRC request message to the base station to initiate an RRC connection recovery process for 4-step SDT. In some embodiments, the RRC request message for initiating the RRC connection recovery process for 4-step SDT includes an information element (IE) for the recovery cause, and the recovery cause IE may be set to mo-data.

[0157] In some embodiments, the UE first initializes the RRC connection recovery process for SDT, and then sends an RRC request message to the base station based on 4-step SDT. In some embodiments, when the UE initializes the RRC connection recovery process for SDT, a first timer is started; in other embodiments, the first timer is started when the UE sends uplink small packet data and the RRC request message to the base station based on 4-step SDT.

[0158] In some embodiments, msg3 may include the UE's identifier, such as the UE's unique identifier in the core network. In some embodiments, msg3 may include information related to the base station the UE previously connected to, such as the inactive temporary cell radio network temporary identifier (I-RNTI). In some embodiments, msg3 may include information for encryption and integrity protection.

[0159] In some embodiments, the aforementioned uplink small packet data can be transmitted on the DTCH, and the aforementioned RRC message can be transmitted on the CCCH. The MAC layer can encapsulate the small packet data and the RRC request message and send them to the base station through the PHY layer.

[0160] S114: After receiving the RRC request message, the base station sends a contention resolution message to the UE.

[0161] In some embodiments, after receiving uplink small packet data and an RRC request message, the base station can restore the UE context and send the received uplink small packet data to the core network.

[0162] In some embodiments, the contention resolution message is actually a contention resolution identity MAC control element (contention resolution identity MAC CE), which can indicate to the UE that contention resolution was successful. In some embodiments, the UE can determine whether the contention resolution identity MAC CE and msg3 sent in S113 are consistent. If they are consistent, the UE determines that the contention resolution corresponding to the current RA-SDT procedure is successful, or determines that the current RA-SDT procedure is successful.

[0163] S115: The base station sends an RRC response message to the UE.

[0164] In some embodiments, if the core network has downlink small packet data to send to the UE, the core network can send the downlink small packet data to the base station. Then, the base station can send the downlink small packet data to the UE together with the RRC response message. The downlink small packet data can be transmitted on the DTCH and multiplexed at the MAC layer with the RRC response message transmitted on the DCCH.

[0165] In some embodiments, the UE can determine whether the uplink small packet data transmission was successful based on the RRC response message, as shown in the following example:

[0166] Example 1: The RRC response message sent by the base station may be an RRC connection release (RRCConnectionRelease) message, an RRC connection restore (RRCConnectionResume) message, an RRC connection setup (RRCConnectionSetup) message, an RRCRelease message, an RRCResume message, or an RRCSetup message, or other RRC messages with the same function but not standardized by 3GPP. If the UE receives the above RRC response message, it can determine that the SDT transmission was successful and stop the first timer.

[0167] Example 2: The RRC response message sent by the base station is an RRC Connection Reject message, an RRCReject message, or other RRC messages with the same function but not standardized by 3GPP. If the UE receives the above RRC response message, it can determine that the SDT transmission has failed and stop the first timer.

[0168] In some embodiments, the UE can remain in the current RRC state or enter another RRC state based on the RRC response message, as shown in the following examples:

[0169] Example 1: If the core network has no further data transmission requirement, the base station sends the following RRC response message: RRC Early Data Complete (RRCEarlyDataComplete), RRCConnectionRelease, RRCLease withsuspend config, RRCLease, or other RRC messages with the same function but not standardized by 3GPP. Upon receiving the above RRC response message, the UE can consider the SDT transmission process successful and stop the first timer. Furthermore, the UE can respond to the above RRC response message and remain in the current non-RRC connected state. Optionally, the above RRC response message (such as the RRCLease message) may include the next-hop chaining count (NCC) calculation for the UE's encrypted small packet data when the UE initiates the next SDT.

[0170] Example 2: If the core network requires further data transmission, it can trigger a connection establishment indication process. The base station sends the aforementioned RRC response message, which may be an RRCConnectionSetup message, an RRCConnectionResume message, an RRCSetup message, an RRCResume message, or another RRC message with the same function but not standardized by 3GPP. Upon receiving the aforementioned RRC response message, the UE can consider the SDT transmission process successful and stop the first timer. Furthermore, the UE can respond to the aforementioned RRC response message and enter the RRC CONNECTED state.

[0171] In some embodiments, if the UE does not receive the RRC response message in S115, it is considered that the small packet data transmission in S113 has failed. For example, if the first timer expires and the UE still has not received the RRC response message, it is considered that the small packet data transmission in S113 has failed. If the UE receives the RRC response message in S115, it is considered that the small packet data transmission in S113 has succeeded. That is, the UE can determine whether the small packet data in S113 has been successfully transmitted by whether or not it has received the RRC response message.

[0172] It should be noted that whether the core network has a need for further data transmission does not include the need for base stations to send downlink small packet data in S115.

[0173] Please see Figure 6 , Figure 6 An exemplary flowchart of a 4-step SDT process under control plane is shown. Figure 6 The process shown may include, but is not limited to, the following steps:

[0174] S121: The UE sends a random access preamble to the base station.

[0175] S122: In response to a random access preamble, the base station sends a RAR to the UE.

[0176] Specifically, S121-S122 and Figure 5 The S111-S112 are similar and will not be described in detail.

[0177] S123: The UE sends an RRC request message carrying uplink small packet data to the base station on the resources allocated by RAR.

[0178] Specifically, S123 and Figure 5Similar to S113, the difference is that the uplink small packet data is not sent after being encapsulated at the MAC layer together with msg3, but is instead carried within msg3. In some embodiments, the aforementioned uplink small packet data can be carried within msg3 and transmitted on the CCCH. For example, the aforementioned uplink small packet data can be carried within the NAS layer-related IE (such as dedicated information NAS IE) contained in the RRCEarlyDataRequest message and transmitted on the CCCH.

[0179] S124: After receiving the RRC request message, the base station sends a contention resolution message to the UE.

[0180] Specifically, S124 and Figure 5 Similar to S114, the difference lies in that the RRC request message received by the base station includes uplink small packet data. In some embodiments, the base station can send the uplink small packet data to the core network via msg3, which carries the uplink small packet data. For example, the base station can send the uplink small packet data to the core network by forwarding the NAS layer-related IE contained in msg3.

[0181] S125: The base station sends an RRC response message to the UE.

[0182] Specifically, S125 and Figure 5 Similar to the S115, it will not be described in detail again.

[0183] Figure 5 and Figure 6 The following explanation uses the example of the UE actively initiating small packet data transmission when it sends uplink small packet data to the base station, executing S111 and / or S121. However, in actual implementations, there are also cases where the UE passively initiates small packet data transmission under the instruction of the base station, such as in LTE's Mobile Termination (MT) EDT (MT-EDT). The transmission process in this case is different from... Figure 5 and Figure 6 The transmission process shown is similar, with the differences described below:

[0184] Prior to S111, when the core network has downlink small packet data to send to the UE, the core network can send a paging message to the base station. In some embodiments, the paging message can carry downlink small packet data volume information. In some embodiments, the base station can send a paging message to the UE, and the UE determines to initiate a 4-step SDT based on the relative magnitude of the currently measured RSRP and a preset RSRP threshold. For example, the base station can trigger MT-EDT according to the paging message and send a paging message carrying an MT-EDT indication to the UE, so that the UE triggers MO-EDT for MT-EDT. The difference from the above-described UE-initiated small packet data transmission process is that in S113, the UE can only send an RRC message to the base station without sending uplink small packet data. Optionally, it can also carry the reason information for triggering MT-EDT. Correspondingly, the base station can receive downlink small packet data sent by the core network, and in S115, the base station can send an RRC response message and downlink small packet data to the UE.

[0185] Similarly, prior to S121, when the core network has downlink small packet data to send to the UE, the core network can send a paging message to the base station. In some embodiments, this paging message can carry downlink small packet data volume information. In some embodiments, the base station can send a paging message to the UE, and the UE determines to initiate a 4-step SDT based on the relative magnitude of the currently measured RSRP and a preset RSRP threshold. Unlike the process described above where the UE actively initiates small packet data transmission, the RRC message sent by the UE to the base station in S123 may not carry uplink small packet data; optionally, it may also carry the reason information for triggering MT-EDT. Accordingly, the base station can receive the downlink small packet data sent by the core network. The RRC response message sent by the base station to the UE in S125 may carry downlink small packet data.

[0186] Please see Figure 7 , Figure 7 An exemplary flowchart of a 2-step SDT process in the user plane is shown. Figure 7 The process shown may include, but is not limited to, the following steps:

[0187] S211: The UE sends a random access preamble, an RRC request message, and uplink small packet data to the base station.

[0188] In some embodiments, the transmission resources for the UE to perform S211 can be obtained through information broadcast by the base station. For example, the UE can use the RA resources broadcast by the base station to send a random access preamble, and the UE can use the PUSCH resources broadcast by the base station to send an RRC request message.

[0189] In some embodiments, the base station can use different random access preambles to distinguish the UE's intent. In other embodiments, the base station can use different resources for receiving random access preambles to distinguish the UE's intent. In still other embodiments, the base station can obtain the UE's intent through the BSR sent by the UE. In yet another embodiment, the RRC request message can carry intent information, which is used to indicate the UE's intent in sending the RRC request message, such as whether the UE's intent is to perform RA-SDT or to initiate RA. See above for details. Figure 5 Examples of S111 and S113 will not be repeated here.

[0190] In some embodiments, the RRC request message in msgA may differ depending on the UE's RRC state and the service scenario. See above for details. Figure 5 An example of an RRC request message in msg3 will not be repeated here.

[0191] In some embodiments, the aforementioned RRC request message and uplink small packet data can be carried in the physical uplink share channel (PUSCH) payload. The uplink small packet data can be transmitted on the DTCH, and the aforementioned RRC message can be transmitted on the CCCH. The MAC layer can encapsulate the small packet data and RRC request message and send them to the base station through the PHY layer.

[0192] In some embodiments, the UE may send uplink small packet data and an RRC request message to the base station to initiate an RRC connection recovery process for 2-step SDT. In some embodiments, the resumeCause IE in the RRC request message for initiating an RRC connection recovery process for 2-step SDT may be set to mo-data.

[0193] In some embodiments, the UE first initializes the RRC connection recovery procedure for SDT, and then sends an RRC request message to the base station based on 2-step SDT. In some embodiments, when the UE initializes the RRC connection recovery procedure for SDT, a first timer is started; in other embodiments, the first timer is started when the UE sends uplink small packet data and the RRC request message to the base station based on 2-step SDT.

[0194] For details on RRC request messages and uplink small packet data, please refer to the above. Figure 5 The descriptions of the RRC request message and uplink small packet data in S113 will not be repeated here.

[0195] S212: After receiving the RRC request message, the base station sends message B to the UE.

[0196] In some embodiments, after receiving uplink small packet data and an RRC request message, the base station can restore the UE context and send the received uplink small packet data to the core network.

[0197] In some embodiments, the message sent by the base station to the UE in the second step of the 2-step RA can be called message B, or msgB for short. For example, msgB includes a success RAR or a fallback RAR.

[0198] In some embodiments, msgB includes a successRAR, which includes a contention resolution field, such as the content of the contention resolution MAC CE. When the UE receives the successRAR, it determines that the contention resolution for the current RA-SDT procedure has been successfully resolved, or that the current RA-SDT procedure has been successful. Optionally, the contention resolution field in the successRAR can indicate that the contention resolution for the UE has been successfully resolved. Optionally, the UE can determine whether the contention resolution field in the successRAR is consistent with msgA sent in S211. If they are consistent, it determines that the contention resolution for the current RA-SDT procedure has been successfully resolved, or that the current RA-SDT procedure has been successful. In other embodiments, msgB includes a fallbackRAR. After receiving the fallbackRAR, the UE resends msg3 and uplink small packet data to the base station.

[0199] S213: The base station sends an RRC response message to the UE.

[0200] In some embodiments, if the core network has downlink small packet data to send to the UE, the core network can send the downlink small packet data to the base station. Then, the base station can send the downlink small packet data to the UE along with the RRC response message.

[0201] For an explanation of the RRC response message, please refer to the above. Figure 5 The description of the RRC response message in S115 will not be repeated here.

[0202] Please see Figure 8 , Figure 8 An exemplary flowchart of a 2-step SDT process under control plane is shown. Figure 8 The process shown may include, but is not limited to, the following steps:

[0203] S221: The UE sends a random access preamble and an RRC request message carrying uplink small packet data to the base station.

[0204] Specifically, S221 and Figure 7 Similar to S211, the difference is that the uplink small packet data is not sent together with the RRC request message in msgA, but is sent in the RRC request message in msgA. In some embodiments, the RRC request message carrying the uplink small packet data can be carried in the physical uplink share channel (PUSCH) payload and can be transmitted on CCCH.

[0205] S222: After receiving the RRC request message, the base station sends msgB to the UE.

[0206] Specifically, S222 and Figure 7 Similar to S212, the difference lies in that the RRC request message received by the base station includes uplink small packet data. In some embodiments, the base station can send the uplink small packet data to the core network through the aforementioned RRC request message carrying uplink small packet data. For example, the base station can send the uplink small packet data to the core network by forwarding an RRCResumeRequest message carrying uplink small packet data.

[0207] S223: The base station sends an RRC response message to the UE.

[0208] Specifically, S223 and Figure 7 Similar to S213, it will not be described in detail again.

[0209] Figure 7 and Figure 8 The following explanation takes the UE actively initiating the transmission of small packet data as an example, where S211 and / or S221 are executed when uplink small packet data is being sent to the base station. However, in actual implementations, there are also cases where the UE passively initiates the transmission of small packet data under the instruction of the base station. The transmission process in this case is different from... Figure 7 and Figure 8 The transmission process shown is similar, with the differences described below:

[0210] Prior to S211, when the core network has downlink small packet data to send to the UE, the core network can send a paging message to the base station. In some embodiments, the paging message can carry downlink small packet data volume information. In some embodiments, the base station can send a paging message to the UE, and the UE determines to initiate a 2-step SDT based on the relative magnitude of the currently measured RSRP and a preset RSRP threshold. For example, the base station can trigger MT-EDT according to the paging message and send a paging message carrying an MT-EDT indication to the UE, so that the UE triggers MO-EDT for MT-EDT. The difference from the above-described UE-initiated small packet data transmission process is that in S211, the UE can only send a random access preamble and RRC request message to the base station without sending uplink small packet data. Optionally, it can also carry the reason information for triggering MT-EDT. Correspondingly, the base station can receive downlink small packet data sent by the core network, and in S213, the base station can send an RRC response message and downlink small packet data to the UE.

[0211] Similarly, prior to S221, when the core network has downlink small packet data to send to the UE, the core network can send a paging message to the base station. In some embodiments, this paging message can carry downlink small packet data volume information. In some embodiments, the base station can send a paging message to the UE, and the UE determines to initiate a 2-step SDT based on the relative magnitude of the currently measured RSRP and a preset RSRP threshold. Unlike the UE-initiated small packet data transmission process described above, the RRC message sent by the UE to the base station in S221 may not carry uplink small packet data; optionally, it may carry the reason information for triggering MT-EDT. Accordingly, the base station can receive the downlink small packet data sent by the core network. The RRC response message sent by the base station to the UE in S223 may carry downlink small packet data.

[0212] Not limited to the examples shown above, in other embodiments, the base station may also send the msgB and RRC response messages together to the UE.

[0213] In some embodiments, after a UE initiates RA-SDT, it cannot complete the transmission of small data by sending only msg3 or msgA. The UE can complete the subsequent small data transmission through subsequent transmissions. These subsequent transmissions can be performed after the UE receives the contention resolution and before the base station sends an RRC response message to the UE, for example... Figure 5 Between S114 and S115, on the upper Figure 7Between S212 and S213. A specific example is shown below:

[0214] Example 1: The UE's current RA-SDT is used to transmit small data (e.g., an instant messaging message). When the UE initiates a 4-step SDT, the UL grant indicated by the base station in the RAR is less than the sum of resources for transmitting the small data and the RRC request message. Alternatively, when the UE initiates a 2-step SDT, the transmission resources obtained by the UE from the broadcast message are less than the sum of resources for transmitting the random access preamble, small data, and the RRC request message. In this case, the UE can first send part of the small data via msg3 or msgA, and then transmit the remaining small data via subsequent transmission. For example, after sending a contention resolution to the UE, the base station can dynamically schedule uplink resources for the UE to perform subsequent transmission.

[0215] Example 2: The RA-SDT initiated by the UE is used to transmit multiple small data. When the small data arrives, the UE can initiate a 4-step SDT or a 2-step SDT to transmit the small data via msg3 or msgA. However, if the UE acquires new small data during this SDT process, the UE can transmit the new small data through subsequent transmission. For example, after sending a contention resolution to the UE, the base station can dynamically schedule uplink resources for the UE to perform subsequent transmission.

[0216] Please see Figure 9 , Figure 9 An exemplary flowchart of a user-facing CG-SDT process is shown. Figure 9 The process shown may include, but is not limited to, the following steps:

[0217] S311: The UE sends an RRC request message and uplink small packet data to the base station on pre-configured resources.

[0218] For example, the pre-configured resource is configured resource type 1 (CGType 1) or PUR. CG Type 1 can be an uplink resource directly configured by the RRC layer, and may include, but is not limited to, the time-frequency resource location and resource period of the uplink resource.

[0219] In some embodiments, when both the base station and the UE support CG-SDT, and the UE meets the conditions for using CG-SDT, the UE can execute S311 without having to execute RA. Conditions for using CG-SDT include, for example, that the UE is in a non-RRC connected state, the UE has uplink small packet data transmission requirements, the UE has pre-configured resources, meets RSRP conditions, and has a valid TA.

[0220] In some embodiments, the UE determines that the conditions for using CG-SDT include at least one of the following:

[0221] Condition 1: TAT is running, meaning the UE's TA is valid and the UE and the base station are in uplink synchronization state, which indicates that CG-SDT is valid; otherwise, it is invalid.

[0222] Condition 2: Under the premise of TAT operation, if the UE's current RSRP is greater than the preset first RSRP threshold (referred to as RSRP 1), it indicates that CG-SDT is effective. Optionally, RSRP 1 can be the RSRP at which the UE can initiate SDT transmission. That is, if the UE's current RSRP is greater than the preset RSRP 1, it means that the UE is close to the base station, the channel quality is good, and if CG-SDT is performed, the success rate is high, and CG-SDT is effective. If the UE's current RSRP is less than or equal to the preset RSRP 1, it means that the UE is far from the base station, the channel quality is poor, and if CG-SDT is performed, the success rate is low. RSRP 1 can be configured by the base station for both CG-SDT and RA-SDT.

[0223] Condition 3: If the increase or decrease in the UE's RSRP is less than or equal to a preset second RSRP threshold (RSRP 2) within the preset time period of the previous TA validity, then CG-SDT is valid. In other words, the increase or decrease in the UE's RSRP can determine whether the UE has moved. If the increase or decrease in RSRP is greater than or equal to RSRP 2, it indicates that the UE has moved or moved a significant distance within the time period of the previous TA validity. If CG-SDT is performed, the success rate is low, and CG-SDT is invalid. If the increase or decrease in RSRP is less than RSRP 2, it indicates that the UE has not moved or moved a small distance within the time period of the previous TA validity. If CG-SDT is performed, the success rate is high, and CG-SDT is valid.

[0224] Condition 4: If the base station configures CG-SDT on SUL and / or NUL, the UE needs to compare its current RSRP with the base station's preset third RSRP threshold (RSRP 3) to determine whether the CG-SDT configured on SUL or NUL is valid. Optionally, assuming CG-SDT is configured on both SUL and NUL, the UE compares its current RSRP with RSRP 3. If the current RSRP is less than RSRP 3, the UE selects the CG-SDT on SUL; if the current RSRP is greater than or equal to RSRP 3, the UE selects the CG-SDT on NUL. In other words, if the base station configures CG-SDT on both SUL and NUL, and the UE's current RSRP is less than RSRP 3, it means the UE is far from the base station, and the CG-SDT configured on SUL should be used. That is, the CG-SDT on SUL is valid, and the CG-SDT on NUL is invalid. If the UE's current RSRP is greater than or equal to RSRP 3, it indicates that the UE is relatively close to the base station and should use the CG-SDT configured on the NUL. In other words, the CG-SDT on the NUL is valid, while the CG-SDT on the SUL is invalid. Alternatively, assuming the base station only configures CG-SDT on the SUL, the UE compares its current RSRP with RSRP 3. If the current RSRP is less than RSRP 3, the UE selects the CG-SDT on the SUL, in which case the CG-SDT is valid. If the current RSRP is greater than or equal to RSRP 3, the CG-SDT cannot be used; that is, the CG-SDT on the SUL is invalid. In other words, if the base station has configured CG-SDT on the SUL and the UE is relatively far from the base station, the CG-SDT on the SUL can be used; otherwise, the CG-SDT on the SUL is invalid. Optionally, assuming the base station only configures CG-SDT on NUL, the UE compares the current RSRP with RSRP 3. If the current RSRP is less than RSRP 3, CGSDT cannot be used. If the current RSRP is greater than or equal to RSRP 3, CGSDT on NUL is selected, that is, CG-SDT on NUL is valid. In other words, if the base station has configured CG-SDT on NUL and the UE is relatively close to the base station, it can use CG-SDT on NUL; otherwise, CG-SDT on NUL is invalid.

[0225] Condition 5: The UE is within the coverage area of ​​the base station, and the base station has configured CG resources for CG-SDT for the UE.

[0226] In some embodiments, prior to S311, the UE may also request the base station to configure pre-configured resources for initiating CG-SDT. For example, the UE sends a CG-SDT resource request message to the base station in the RRCCONNECTED state. The CG-SDT resource request message is used to request the base station to configure CG-SDT. For example, in LTE, the UE sends a PUR Configuration Request message to the base station.

[0227] Optionally, the UE can send a CG-SDT resource request message to the base station at any time while in the RRCCONNECTED state. Optionally, if the UE is in the RRCCONNECTED state and determines that small packet data may be available in the future, it can send a CG-SDT resource request message to the base station. Optionally, if the UE is in the RRCCONNECTED state and has no need to transmit data with the base station within a preset time period, and the UE determines that it may soon enter a non-RRC connected state, it can send a CG-SDT resource request message to the base station in order to transmit small packet data in the non-RRC connected state.

[0228] In some embodiments, after the base station receives configuration request information (e.g., a CG-SDT resource request message or a PURConfigurationRequest message), when the base station instructs the UE to switch from RRC CONNECTED state to non-RRC connected state, the RRC response message sent by the base station to the UE may carry detailed CG-SDT configuration information. For example, when the base station instructs the UE to switch from RRC CONNECTED state to RRC INACTIVE state, the aforementioned RRC response message is an RCRelease message, which may carry detailed CG resource configuration information. Similarly, when the base station instructs the UE to switch from RRC CONNECTED state to RRC IDLE state, the aforementioned RRC response message is an RCRelease message, which may carry detailed PUR configuration information.

[0229] In addition to the cases listed above, in other embodiments, after the base station configures a CG-SDT for the UE, it can send an RRC response message carrying release indication information to the UE to release the configured CG-SDT. For example, the RRCRelease message can carry release indication information for CG resources. For example, the RRCConnectionRelease message can carry release indication information for PURs.

[0230] In other embodiments, the UE may not send a CG-SDT resource request message to the network device. The network device can directly configure CG-SDT resources for the UE. For example, the network device can refer to the UE's historical communication service information to configure CG-SDT resources for the UE.

[0231] In some embodiments, the UE may send uplink small packet data and an RRC request message to the base station to initiate an RRC connection recovery process for CG-SDT. In some embodiments, resumeCause IE may be set to mo-data in the RRC request message used to initiate the RRC connection recovery process for CG-SDT.

[0232] In some embodiments, the UE first initializes the RRC connection recovery process for SDT, and then sends an RRC request message to the base station based on CG-SDT. In some embodiments, when the UE initializes the RRC connection recovery process for SDT, a first timer is started; in other embodiments, the first timer is started when the UE sends uplink small packet data and the RRC request message to the base station based on CG-SDT.

[0233] Beyond the examples above, in other embodiments, the UE may send only small packet data during CG-SDT. For instance, if the resource indicated by the CG-SDT configuration is a unique resource configured for the UE by the network device, rather than a shared resource, the UE may send only small packet data on that resource during CG-SDT. This allows the network device to identify the UE sending the small packet data based on the resource receiving the small packet data. Alternatively, if the resource indicated by the CG-SDT configuration is a shared resource configured for multiple UEs by the network device, the UE may send small packet data and an RRC request message on the resource indicated by the CG-SDT configuration during SDT. This allows the network device to identify the UE using the RRC message.

[0234] For details on RRC request messages and uplink small packet data, please refer to the above. Figure 5 The descriptions of the RRC request message and uplink small packet data in S113 will not be repeated here.

[0235] S312: The base station sends a feedback response message to the UE.

[0236] In some embodiments, the base station responds to an RRC request message sent by the UE by sending a feedback response message to the UE. In some embodiments, the feedback response message is used to indicate that the RRC request message was successfully transmitted. In some embodiments, the feedback response message is used to indicate that the RRC request message and the uplink small packet data sent with the RRC request message were successfully transmitted. In some embodiments, the feedback response message is used to indicate that the uplink small packet data transmission was successful.

[0237] In some embodiments, the feedback response message is a Layer 1 Acknowledgement (Layer 1Ack), i.e., a physical layer ACK.

[0238] In some embodiments, the feedback response message is downlink feedback information (DFI), i.e., CG-DFI.

[0239] In some embodiments, the feedback response message is a MAC CE from the MAC layer.

[0240] In some embodiments, the feedback response message is an RRC message from the RRC layer.

[0241] S313: The base station sends an RRC response message to the UE.

[0242] In some embodiments, if the core network has downlink small packet data to send to the UE, the core network can send the downlink small packet data to the base station. Then, the base station can send the downlink small packet data to the UE along with the RRC response message.

[0243] For an explanation of the RRC response message, please refer to the above. Figure 5 The description of the RRC response message in S115 will not be repeated here.

[0244] In some embodiments, the RRC response message may include CG-SDT configuration. For example, the CG-SDT configuration in S311 is used by the UE to transmit small packet data in S311, and the CG-SDT configuration indicated by the RRC response message in S313 is used by the UE to transmit small packet data next time.

[0245] In some embodiments, when the feedback response message in S312 is an RRC message from the RRC layer, the feedback response message in S312 and the RRC response message in S313 can be the same message. That is, the feedback response message can be the RRC response message, meaning that S312 and S313 are the same step.

[0246] Please see Figure 10 , Figure 10An exemplary flowchart of a CG-SDT process under the control plane is shown. Figure 10 The process shown may include, but is not limited to, the following steps:

[0247] S321: The UE sends an RRC request message carrying uplink small packet data to the base station on pre-configured resources.

[0248] Specifically, S321 and Figure 9 Similar to S311, the difference is that the uplink small packet data is not sent together with the RRC request message, but is sent in the RRC request message.

[0249] S322: The base station sends a feedback response message to the UE.

[0250] S323: The base station sends an RRC response message to the UE.

[0251] Specifically, S322-S323 and Figure 9 The S312-S313 are similar and will not be described in detail.

[0252] Figure 9 and Figure 10 The following explanation takes the UE actively initiating the transmission of small packet data as an example, where S311 and / or S321 are executed when uplink small packet data is being sent to the base station. However, in actual implementations, there are also cases where the UE passively initiates the transmission of small packet data under the instruction of the base station. The transmission process in this case is different from... Figure 9 and Figure 10 The transmission process shown is similar, with the differences described below:

[0253] Prior to S311, when the core network has downlink small packet data to send to the UE, the core network can send a paging message to the base station. In some embodiments, this paging message can carry data volume information of the downlink small packet data. In some embodiments, the base station can send a paging message to the UE to enable the UE to initiate CG-SDT. The difference from the above-described UE-initiated small packet data transmission process is that in S311, the UE can only send an RRC request message to the base station without sending uplink small packet data; optionally, it can also carry the reason information for triggering MT-EDT. Correspondingly, the base station can receive the downlink small packet data sent by the core network, and in S313, the base station can send an RRC response message and downlink small packet data to the UE.

[0254] Similarly, prior to S321, when the core network has downlink small packet data to send to the UE, the core network can send a paging message to the base station. In some embodiments, this paging message can carry downlink small packet data volume information. In some embodiments, the base station can send a paging message to the UE to cause the UE to initiate CG-SDT. The difference from the above-described UE-initiated small packet data transmission process is that the RRC message sent by the UE to the base station in S321 may not carry uplink small packet data; optionally, it may also carry reason information for triggering MT-EDT. Accordingly, the base station can receive the downlink small packet data sent by the core network. The RRC response message sent by the base station to the UE in S323 may carry downlink small packet data.

[0255] Understandably, the UE in the RRC INACTIVE state has its RNA managed by the NG-RAN, and the NG-RAN can access the RNA where the UE is located.

[0256] In some embodiments, a UE in the RRC INACTIVE state can be configured with an RNA by the previous serving base station, whereby the RNA may cover one or more cells and may be contained within the core network registration area. In some embodiments, there are Xn connections between base stations within the same RNA.

[0257] In some embodiments, the base station can configure RNA-related information for the UE, such as a cell list or a RAN area list, through the RAN-NotificationAreaInfo (RAN-AreaInfo) IE in the RRC response message (such as the RRC Resume message) sent to the UE.

[0258] The following examples illustrate two scenarios for configuring RNA:

[0259] Scenario 1: The base station configures a cell list for the UE. In some embodiments, the base station explicitly indicates the cell list to the UE, wherein one or more cells included in the cell list constitute the RNA configured by the base station for the UE.

[0260] Scenario 2: The base station configures a RAN area list for the UE. In some embodiments, the RAN area list includes one or more RAN areas that constitute the RNA configured by the base station for the UE. In some embodiments, the base station configures a RAN area identity document (ID) (RAN area ID) for the UE. Each RAN area is a subset of a core network (CN) tracking area or equal to a CN tracking area. Each RAN area is identified by a RAN area ID, and each RAN area includes a tracking area code (TAC), which is the tracking area to which the RAN area belongs. In some embodiments, each RAN area may include a RAN area code, which can be used to identify the area of ​​the RAN area within the tracking area. In some embodiments, each cell and its corresponding base station may broadcast one or more RAN area IDs in the system information.

[0261] Understandably, a UE in the RRC INACTIVE state can trigger an RNA update (RNAU). Optionally, after configuring the RNA, the UE can trigger the RNAU to notify the network device of the terminal's current RNA status, such as the RNA the terminal is currently in, whether it is in the RNA configured by the base station for the UE, the cell the UE is currently in, and other mobility-related states of the UE.

[0262] The following examples illustrate two scenarios that trigger RNAU:

[0263] Scenario 1: The UE can periodically trigger RNAU. Triggering RNAU can be controlled by a second timer, such as T380 as specified in 3GPP protocol 38.321. T380 timeout is used to trigger RNAU. In some embodiments, when the base station sends a first RRC response message to the UE, it configures a second timer for the UE. When the UE receives the first RRC response message, the UE starts the second timer. In some embodiments, the conditions for starting the second timer include the UE receiving the first RRC response message, which is, for example, an RRCResume message, an RRCResume with suspendconfig message, or other RRC messages with the same function but not standardized by 3GPP. In some embodiments, when the second timer times out, the UE triggers RNAU. In some embodiments, when the UE receives a second RRC response message sent by the base station, the UE stops the second timer. In some embodiments, the conditions for stopping the second timer include the UE receiving a second RRC response message, which is, for example, an RRCResume message, an RRCSetup message, or an RRCResume message, or other RRC messages with the same function but not standardized by 3GPP.

[0264] Scenario 2: The RNAU is triggered by system information block (SIB) 1, and the triggered RNAU is related to the RNA configured by the base station for the UE. In some embodiments, the UE can trigger the RNAU if its serving cell is not in the configured RNA. For example, if the serving cell after cell reselection is not in the configured RNA, the UE can trigger the RNAU, such as when the terminal moves and cell reselection occurs. In some embodiments, after the UE reads SIB1 in the serving cell (e.g., the new serving cell after cell reselection), if the cell provided by SIB1 is not in the cell list configured by the base station for the UE, or if the RAN area provided by SIB1 is not in the RAN area list configured by the base station for the UE, the UE can trigger the RNAU. For example, if the cell identifier read by the UE from SIB1 is not included in the cell identifiers included in the cell list configured by the base station for the UE in the RAN-NotificationAreaInfoIE, the UE can trigger the RNAU. For example, if the TAC of the cell read by the UE from SIB1 is not included in the TACs included in the RAN area list configured by the base station for the UE in the RAN-NotificationAreaInfoIE, the UE can trigger the RNAU.

[0265] The following section provides an example of how to implement RNAU.

[0266] In some embodiments, when a UE triggers RNAU, it can initiate an RRC connection recovery procedure for RNAU. In some embodiments, the UE initiating the RRC connection recovery procedure for RNAU may include: the UE's RRC layer initiating a process to request the resumption of a suspended RRC connection. In some embodiments, the UE initiating the RRC connection recovery procedure for RNAU may include: the UE sending an RRC request message to the base station, such as an RRCResumeRequest message or an RRCResumeRequest1 message, wherein the resumeCause IE in the RRC request message can be set to rna-Update.

[0267] In some embodiments, the UE-initiated RRC connection restoration procedure for RNAU may further include initializing the RRC connection restoration procedure, specifically including: if an emergency service is currently in progress, the UE can select Access Category 2 and set the resumeCause IE in the RRC request message sent during the RRC connection restoration procedure to emergency. If no emergency service is currently in progress, the UE can select Access Category 8. The Access Category can be used for access barring checks, and each access request can be associated with one Access Category, allowing the base station to control the UE's access requests. In some embodiments, the access request can be an RRC connection restoration request initiated by the UE.

[0268] In some embodiments, during the initialization of RRC connection recovery, the UE selects an Access Category. The UE can then execute a unified access control (UAC) procedure and determine whether the access attempt is blocked. For example, each access attempt corresponds to an Access Category. If the access attempt is for initiating an RRC connection recovery procedure for RNAU, the Access Category might be 2 or 8. When the access attempt is blocked, the UE cannot initiate an RRC connection recovery procedure for RNAU. When the access attempt is not blocked, the UE can initiate an RRC connection recovery procedure for RNAU, as detailed below:

[0269] Optionally, if the access attempt is blocked, the UE can set the first variable to the first value and stop the access attempt.

[0270] Optionally, if an access attempt is blocked, the UE can start a timer T390. For example, the UE can start a timer T390 corresponding to the Access Category of the blocked access attempt. When the T390 of the Access Category runs, the UE considers the access attempt to be blocked. When the T390 of the access attempt times out, for example, when the T390 of the access attempt does not run, the UE considers the blocking of the Access Category to be mitigated, for example, when the Access Category is 2 or the Access Category is 8.

[0271] In this context, the first variable takes either a first value or a second value. For example, the first variable indicates whether there is a pending RNA update, with a first value being true and a second value being false. In some embodiments, a first value for the first variable can indicate that there is a pending RNA update process. In some embodiments, a second value for the first variable can indicate that there is no pending RNA update process. In some embodiments, a first value for the first variable can indicate that RNAU has been triggered but not successfully executed (which can be understood as the RRC ligation recovery process for RNAU not being successfully executed).

[0272] If the access attempt is not blocked, the UE can continue to perform initialization related to the RRC connection recovery process, such as applying the default physical layer configuration, default SRB1 configuration, default MAC layer configuration, etc., and the UE can set the first variable to the second value. Then, the UE can initiate the transmission of an RRC request message, such as restoring the RRC configuration, rebuilding the PDCP entity of SRB1, and restoring SRB1. The UE can also transmit the RRC request message to the UE's underlying layer (where the underlying layer is relative to the RRC layer, such as the MAC layer or physical layer). For example, after the UE's RRC layer performs the above initialization process, the RRC layer transmits the RRC request message to the MAC layer, and then the MAC layer sends the RRC request message. In some embodiments, the UE in a non-RRC connected state has not configured transmission resources. When the MAC layer receives a transmission request sent by the RRC layer, it can initiate an RA to send an RRC request message for the RNAU, for example, sending the RRC request message in the above msg3 or above msgA. In other embodiments, the UE in a non-RRC connected state has pre-configured resources, such as CG resources or PURs. The description of the pre-configured resources is as follows... Figures 9-10The description of pre-configured resources is similar. When the lower layer receives a transmission request sent by the upper layer, it can send an RRC request message for RNAU on the pre-configured resources. For example, the lower layer mentioned above is the MAC layer, and the upper layer mentioned above is the RRC layer. For example, the lower layer mentioned above is the physical layer, and the upper layer mentioned above is the RRC layer. For example, the lower layer mentioned above is the physical layer, and the upper layer mentioned above is the MAC layer. After receiving the transmission request sent by the RRC layer, the MAC layer then indicates the transmission request to the physical layer. In the above RRC request message for RNAU, the resumeCause IE is set to rna-Update. In some embodiments, when the base station receives the RRC request message for RNAU sent by the UE, it can obtain that the UE is currently requesting RNAU, and thus know the current state of the UE, such as its mobility.

[0273] In some embodiments, after the base station successfully receives the RRC request message for RNAU sent by the UE, the base station may send a third RRC response message to the UE after successful contention resolution (e.g., after sending a contention resolution message to the UE). The third RRC response message may be, for example, an RRC Resume message, an RRC Resume with suspend indication message, an RRC Resume message, or other RRC messages with the same function but not standardized by 3GPP. Optionally, the UE may consider the RNAU successful upon receiving the third RRC response message. Specific examples are shown below:

[0274] Example 1: The UE performs RNAU under the current base station (which can be called the new station), but the UE's context is stored in the previous base station (which can be called the old station). The old station can send the UE's context to the new station through the Xn interface. After obtaining the UE's context, the new station can send an RRC response message to the UE, such as sending an RRCLease message to make the UE enter the RRCIDLE state, or sending an RRCLeasewith suspend indication message to make the UE enter the RRCINACTIVE state, or sending an RRCResume message to make the UE enter the RRCONNECTED state.

[0275] Example 2: The UE initiates RNAU under the current base station (which can be called the new station), but the UE's context is stored in the previous base station (which can be called the old station). The old station does not send the UE's context to the new station. At this time, the UE's RRC state is controlled by the old station. The old station can indirectly send an RRC response message to the UE through the Xn interface message, that is, send the RRC response message to the new station, and then the new station forwards the RRC response message. For example, forwarding the RRCLease message to make the UE enter the RRCIDLE state, or forwarding the RRCLeasewith suspend indication message to make the UE enter the RRC_INACTIVE state.

[0276] In other embodiments, the base station sends a fourth RRC response message to the UE. For example, if the base station fails to receive the RRC request message for RNAU sent by the UE, the base station may send a fourth response message to the UE after successfully resolving the contention. The fourth RRC response message may be, for example, an RRCConnectionReject message, an RRCReject message, or other RRC messages with the same function but not standardized by 3GPP. Optionally, upon receiving the fourth RRC response message, the UE may return to the RRC_INACTIVE state. Optionally, upon receiving the fourth RRC response message, the UE may consider the RRC recovery request for RNAU to have been rejected and may set the first variable to a first value.

[0277] In some embodiments, after the UE receives the fourth RRC response message, if the fourth RRC response message is configured with a wait time, the UE starts timer T302, where the duration of timer T302 is equal to the wait time. When timer T302 runs and the Access Category is not 2 or 0, the UE considers the access attempt to be blocked. When timer T302 expires, if Access Category T390 has not run, the UE considers the blocking of the Access Category to be mitigated. It should be noted that timer T302 blocks the UE's request, without distinguishing the UE's Access Category.

[0278] In some embodiments, if the UE initiates an RRC connection recovery procedure for RNAU and selects AccessCategory 8, and if the access attempt is not prohibited during the initialization of this RRC connection recovery procedure for RNAU, the UE will not enable T390 for Access Category 8. The UE can then continue to perform the initialization related to this RRC connection recovery procedure and send an RRC request message for the RRC connection recovery procedure for RNAU. If the base station sends a fourth RRC response message configured with a wait time to the UE, the UE starts timer T302. When timer T302 expires, T390 for Access Category 8 is not running, and the UE considers the prohibition of Access Category 8 to be mitigated.

[0279] In some embodiments, the UE can continue executing the RNAU by setting a first variable to a first value when the current RNAU has been triggered but not successfully executed. For example, after the UE triggers the RNAU, if the access attempt is blocked, or if a fourth RRC response message (such as an RRCReject message) is received during the RRC connection recovery process for the RNAU, the UE can set the first variable to a first value. In some embodiments, with the first variable set to a first value, the UE can continue to attempt to initiate the RRC connection recovery process for the RNAU. In some embodiments, if the blocking for Access Category 8 or Access Category 2 is mitigated, and the upper layer (such as the NAS layer) does not request the recovery of the RRC connection (e.g., the upper layer (such as the NAS layer) does not request the recovery of the RRC connection for data transmission), and the first variable is set to a first value, the UE can continue to initiate the RRC connection recovery process for the RNAU.

[0280] Currently, when a UE in a non-RRC connected state is performing SDT with a base station, RNAU may be triggered. In this case, the terminal may stop the current SDT and execute RNAU, thereby affecting the transmission of small data in the SDT. A specific example is shown below:

[0281] Example 1: Before the UE and base station perform RA SDT, the UE receives an RRC Restore message from the base station, starts a second timer (e.g., T380), and then the UE initiates the RRC connection recovery procedure for SDT, for example... Figure 5 and Figure 6 The 4-step SDT shown, or above Figure 7 and Figure 8The 2-step SDT shown can have a second timer that starts before the UE sends the randomaccess preamble. If the second timer times out before the UE receives the contention resolution message from the base station (i.e., RNAU is triggered before the UE receives the contention resolution message), this can be understood as a new RA for RNAU being triggered during the current RA for SDT. In this case, whether to execute RNAU depends on the UE implementation; the UE implementation decides to continue the current RA process for SDT or execute the new RA for RNAU. If the UE executes the new RA for RNAU, it may result in uplink and downlink small packet data not being sent or failing to be sent, such as uplink small packet data sent with msg3 or msgA, and downlink small packet data sent with RRC response messages. If the second timer times out after the UE receives the contention resolution message from the base station (i.e., RNAU is triggered after the UE receives the contention resolution message from the base station), this can also be interpreted as a different scenario. In this situation, the UE needs to discard the currently running RA SDT procedure and initiate the RRC connection recovery procedure for RNAU. This may result in uplink small packet data and downlink small packet data being unable to be sent or failing to be sent. For example, uplink small packet data and / or downlink small packet data that need to be transmitted in subsequent transmission, and downlink small packet data sent together with the RRC response message.

[0282] Example 2: Before the UE and base station perform CG-SDT, the UE receives an RRC Resume message from the base station, starts a second timer (e.g., T380), and then the UE initiates an RRC connection recovery process for SDT, for example... Figure 9 and Figure 10 The CG-SDT shown can have a second timer started before the UE sends an RRC request message and / or uplink packet data. If the second timer expires, the UE needs to discard the currently running CG-SDT procedure and initiate an RRC connection recovery procedure for RNAU. This may result in uplink and downlink packet data not being sent or failing to be sent, such as the uplink and / or downlink packet data that subsequent transmission needs to transmit, and the downlink packet data sent along with the RRC response message.

[0283] This application provides a method for controlling transmission, which can be applied to a communication system, such as a terminal and a network device. When the terminal and network device perform SDT (Small Data Transmission), RNAU (Radio Access Unlocking) can be avoided, thus preventing the impact on small data transmission, such as increased transmission latency. Subsequent SDT initiation would also increase power consumption and signaling overhead. Specifically, when the terminal and network device perform SDT, the network device can obtain the RNA (Radio Access Location) where the terminal is located, without needing to additionally execute RNAU to notify the network device of the terminal's current state.

[0284] The following describes an example of how a network device can obtain the RNA (RNAi) where the terminal is located during SDT (Signal-Driven Technology) between the terminal and the network device: Example 1: The base station initiating this SDT is the same as the base station where the terminal last received the RRCLease message. That is, the terminal receives the RRCLease message under the same base station and initiates the RRC connection recovery process for SDT. Optionally, the base station that last received the RRCLease message can be the base station that configured the RNA for the terminal. This base station can use the RRCLease message to configure the RNA information for the terminal. That is, the terminal is configured with RNA under the same base station and initiates SDT. This base station stores the terminal's context. This base station can know the RNA where the terminal is located. For example, the base station can know the previously configured RNA for the terminal based on its stored terminal context. Since the terminal initiating SDT has not moved outside the configured RNA range, the base station can know that the RNA where the terminal is located is the configured RNA.

[0285] Example 2: The base station initiating SDT this time (referred to as the new base station) is different from the base station where the terminal last received the RRC Restore message (referred to as the old base station). That is, the terminal initiates the RRC connection recovery process for SDT under the new base station. Optionally, the old base station where the terminal last received the RRC Restore message can be the base station that configured the RNA for the terminal. The old base station can use the RRC Restore message to configure relevant information about the RNA for the terminal. The new base station can know the RNA where the terminal is located. For example, the new base station can obtain the terminal's context from the old base station. Based on the obtained terminal context and / or the information from the old base station, the new base station can determine whether the terminal is outside the RNA range configured by the old base station for the terminal. For example, if the RNA configuration obtained by the new base station from the terminal's context does not include the RNA list or cell list corresponding to the new base station, it can be determined that the terminal has exceeded the configured RNA range; otherwise, it can be determined that the terminal has not moved outside the configured RNA range. For example, if the RNA list corresponding to the new base station does not include the RNA list corresponding to the old base station, or if the cell list corresponding to the new base station does not include the cell list corresponding to the old base station, then it can be known that the terminal has exceeded the RNA range configured above. Otherwise, it can be known that the terminal has not moved outside the RNA range configured above.

[0286] The control transmission method provided in the embodiments of this application will be described next based on the above description. This method can be applied to... Figure 1 The communication system shown in this method can have network devices and terminals that are... Figure 1 The network devices 120 and UE130 are shown.

[0287] The following embodiments illustrate the transmission process under the user plane protocol stack. The first and second timers in the following embodiments can be found in the descriptions of the first and second timers above.

[0288] In one possible implementation, when the terminal is in a non-RRC connection state, an RRC connection recovery process for RNAU is executed when a first preset condition is met. For an explanation of the RRC connection recovery process for RNAU, please refer to the explanation of initiating the RRC connection recovery process for RNAU in the above implementation of RNAU.

[0289] In some embodiments, the first preset condition includes the second timer timing out and the first timer not running, as illustrated in the following examples. Figure 11 As shown, the first preset condition is Figure 11 The first condition in the configuration. In some embodiments, the first preset condition includes the terminal receiving SIB1 of the first serving cell, the first serving cell not belonging to the configured RNA, and the first timer not running. Specific examples are as follows. Figure 13As shown, the first preset condition is Figure 13 The second condition in the above. An example of how this situation can be described is shown below:

[0290] Example 1: When the terminal is in RRC INACTIVE state, if the first timer (e.g., T3XX) does not run and the second timer (e.g., T380) times out, or if the first timer (e.g., T3XX) does not run and the terminal's serving cell does not belong to the configured RNA, the terminal can initiate an RRC connection recovery process and set resumeCause IE in the RRC request message used to initiate the RRC connection recovery process to rna-Update.

[0291] Example 2: When the terminal is in RRC INACTIVE state, if the second timer (e.g., T380) times out or the terminal's serving cell does not belong to the configured RNA, and if the first timer (e.g., T3XX) does not run, the terminal can initiate an RRC connection recovery process and set resumeCause IE in the RRC request message used to initiate the RRC connection recovery process to rna-Update.

[0292] Optionally, performing the RRC connection recovery procedure for RNAU may include, in the example above, initiating the RRC connection recovery procedure and setting the resumeCause IE in the RRC request message used to initiate the RRC connection recovery procedure to rna-Update.

[0293] Please see Figure 11 , Figure 11 This is a flowchart illustrating a method for controlling transmission provided in an embodiment of this application. The method includes, but is not limited to, the following steps:

[0294] S401: The terminal starts the second timer.

[0295] In some embodiments, S401 is an optional step.

[0296] In some embodiments, upon receiving a first RRC response message, the terminal starts a second timer. In some embodiments, the first RRC response message includes the second timer; in some embodiments, the first RRC response message includes the duration of the second timer. The first RRC response message may be, for example, an RRC Resume message, an RRC Resume with suspendconfig message, or other RRC messages with the same function but not standardized by 3GPP.

[0297] S402: When the first condition is met, the terminal triggers RNAU.

[0298] In some embodiments, when the terminal is in the non-RRC connected state and the first condition is met, the RNAU is triggered. Optionally, the non-RRC connected state is the RRC INACTIVE state.

[0299] In some embodiments, the first condition includes that the terminal is in the RRC INACTIVE state.

[0300] In some embodiments, triggering the RNAU is to execute the RRC connection resume procedure for the RNAU. Optionally, when executing the RRC connection resume procedure for the RNAU, the terminal may send an RRC request message to the network device, and the resumeCause IE in the RRC request message is rna-Update.

[0301] Specifically, the first condition includes that the second timer expires and the first timer is not running. Optionally, the first timer not running means it is not started.

[0302] In some embodiments, when the second timer expires, the terminal may determine whether the first timer is running. If the first timer is running, the terminal does not trigger the RNAU. If the first timer is not running, the terminal triggers the RNAU.

[0303] In some embodiments, when the second timer expires and there is no SDT requirement when the second timer is running, the terminal may trigger the RNAU. Optionally, the first timer not running may indicate that the terminal has no SDT requirement. Optionally, when the second timer is running, the first timer is not running. A specific example is as follows Figure 12 shown.

[0304] Please refer to Figure 12 , Figure 12 which exemplarily shows a timing diagram.

[0305] As Figure 12 shown, the horizontal axis is the time axis (t). At the first moment t1, the second timer is started (for example, receiving the first RRC response message). At the second moment t2, the second timer expires, and t1 < t2. The second timer runs between the first moment and the second moment, and the first timer is not running and not started between the first moment and the second moment. At the second moment, the second timer expires and the first timer is not running. At this time, the terminal may trigger the RNAU.

[0306] Optionally, the above-mentioned RRC connection resume procedure for SDT may include: initiating the RRC connection resume procedure and setting the resumeCause IE in the RRC request message for initiating the RRC connection resume procedure to mo-data.

[0307] Please refer to Figure 13 , Figure 13 This is a flowchart illustrating another control transmission method provided in an embodiment of this application. The method includes, but is not limited to, the following steps:

[0308] S501: The terminal starts the first timer.

[0309] In some embodiments, S501 is an optional step.

[0310] In some embodiments, the terminal initiates an RRC connection recovery process for SDT and starts a first timer. Optionally, the first timer is started when the terminal sends an RRC request message and / or uplink small packet data to the network device, for example, when... Figures 5-8 In the illustrated process, when the terminal sends msg3 or msgA to the network device based on RA-SDT, the first timer is started, for example, as shown above. Figures 9-10 In the process shown, when the terminal sends an RRC request message and / or uplink small packet data to the network device based on CG-SDT, the first timer is started.

[0311] S502: Cell reselection has occurred in the terminal.

[0312] In some embodiments, S502 is an optional step.

[0313] In some embodiments, during the SDT process between the terminal and the network device, a cell reselection occurs. In some embodiments, when the terminal performs a cell reselection while the first timer is running, the first timer is stopped.

[0314] In some embodiments, when a terminal undergoes cell reselection and switches from a first cell to a second cell, the serving cell after the cell reselection is the second cell, which will be referred to as the first serving cell. In some embodiments, the terminal's first serving cell is not part of the configured RNA, which is configured by the network device for the terminal before the cell reselection.

[0315] In some embodiments, after a cell reselection occurs, the terminal receives the SIB1 of the current serving cell and determines a first serving cell based on the SIB1. The SIB1 indicates the first serving cell. In some embodiments, the terminal determines based on the SIB1 that the first serving cell does not belong to a configured RNA, wherein the RNA was configured for the terminal by the network device before the cell reselection occurred. Specific examples are shown below:

[0316] Example 1: The terminal reads the cell identifier of the first serving cell from SIB1. When the cell identifier of the first serving cell read is not included in the cell identifiers in the cell list configured by the network device for the terminal in RAN-NotificationAreaInfo IE, the terminal determines that the first serving cell does not belong to the configured RAN.

[0317] Example 2: The terminal reads the TAC of the first serving cell from SIB1. If the TAC of the first serving cell read is not included in the list of TACs in the RAN area configured by the network device for the terminal in the RAN-NotificationAreaInfo IE, the terminal determines that the first serving cell does not belong to the configured RAN.

[0318] In some embodiments, after a cell reselection occurs, the terminal is in a non-RRC connected state. Optionally, this non-RRC connected state is an RRC INACTIVE state.

[0319] S503: When the second condition is met, the terminal triggers RNAU.

[0320] In some embodiments, when the terminal is in a non-RRC connected state, RNAU is triggered when a second condition is met. Optionally, the non-RRC connected state is an RRC INACTIVE state.

[0321] In some embodiments, the second condition includes the terminal being in RRC INACTIVE state after a cell reselection.

[0322] In some embodiments, the RNAU is triggered to perform an RRC connection recovery process for the RNAU. Optionally, when performing the RRC connection recovery process for the RNAU, the terminal may send an RRC request message to the network device, wherein the resumeCause IE in the RRC request message is rna-Update.

[0323] Optionally, the second condition includes the terminal receiving the SIB1 of the first serving cell, the first serving cell not belonging to the configured RNA, and the first timer not running. In some embodiments, the first serving cell is the serving cell after the terminal performs cell reselection. In some embodiments, the first serving cell is the cell indicated by the SIB1 received after the terminal performs cell reselection. The terminal determines that the first serving cell does not belong to the configured RNA based on the SIB1 of the first serving cell. For a specific example, see S502.

[0324] In some embodiments, cell reselection occurs when the terminal has no SDT requirement. Optionally, the first timer not running in the second condition means that the first timer is not enabled. Optionally, the first timer not running can indicate that the terminal has no SDT requirement.

[0325] In some other embodiments, when cell reselection occurs during SDT, the first timer runs during SDT, and cell reselection occurs while the first timer is running. Alternatively, the first timer stops if it does not run in the second condition. Alternatively, the first timer stops when cell reselection occurs. Alternatively, the terminal is in RRC INACTIVE state after cell reselection occurs.

[0326] In some embodiments, the second condition further includes that the terminal cannot perform an SDT procedure in the first serving cell. Optionally, the terminal being unable to perform an SDT procedure in the first serving cell means that the terminal cannot continue a previous SDT procedure in the first serving cell. For example, after a cell reselection, the terminal cannot continue the RRC connection recovery procedure for SDT initiated in S501. Optionally, the terminal being unable to perform an SDT procedure in the first serving cell means that the terminal cannot initiate a new SDT procedure in the first serving cell. For example, after a cell reselection, the terminal cannot continue initiating a new SDT procedure for the RRC connection recovery procedure for SDT initiated in S501, or cannot initiate a new SDT procedure for newly acquired small data. Optionally, the terminal being unable to perform an SDT procedure in the first serving cell means that the terminal does not have SDT-related configuration information in the first serving cell. For example, the first serving cell does not support SDT. Optionally, the first serving cell not supporting SDT includes the first serving cell not broadcasting the relevant SDT configuration in the system information. Another example is that the first serving cell does not support RA-SDT and / or CG-SDT.

[0327] In some embodiments, after cell reselection, if the terminal receives SIB1 of the current serving cell, and the first serving cell indicated by SIB1 does not belong to the configured RNA, the terminal can determine whether the first timer is running. If the first timer is running, the terminal does not trigger RNAU and continues SDT. Optionally, the first timer running means the first timer continues to run, and the terminal can continue the previous SDT process in the serving cell. For example, after cell reselection, if the first timer continues to run, the terminal can continue the RRC connection recovery process for SDT initiated in S501 in the serving cell. Optionally, the first timer running means the first timer is enabled, and the terminal can initiate a new RRC connection recovery process for SDT in the serving cell. For example, after cell reselection, if the terminal initiates a new RRC connection recovery process for SDT and enables the first timer, the terminal can enable it. If the first timer is not running, the terminal triggers RNAU. Optionally, this RNAU is triggered by SIB1.

[0328] In some embodiments, when the terminal performs SDT, if the second timer times out, the terminal can determine whether the first timer is running. If the first timer is running, the terminal does not trigger RNAU and continues the SDT process. After the second timer times out, the terminal performs cell reselection, stops the first timer, and the terminal enters the RRC INACTIVE state. The terminal can execute the RRC connection recovery process for RNAU when the second condition is met.

[0329] In some embodiments, if the terminal is in RRC IDLE state after cell reselection, the terminal will not trigger RNAU. In other embodiments, if the terminal can perform SDT in the first serving cell after cell reselection, the terminal will not trigger RNAU and will perform SDT. Optionally, the case where the terminal can perform SDT in the first serving cell is the opposite of the case where the terminal cannot perform SDT in the first serving cell, as detailed in the above description.

[0330] Understandably, compared to the two scenarios for triggering RNAU in the examples above, this application embodiment adds a triggering condition: the first timer is not running, that is, RNAU can only be triggered when the terminal has no SDT requirement or the SDT process has ended. When the first timer is running (such as during SDT), RNAU will not be triggered. During SDT, the network device can obtain the RNA where the terminal is located. Not executing RNAU will not only not affect the network device's acquisition of the terminal's status, but also avoid affecting the small packet data transmitted during the SDT process, such as avoiding increased transmission latency and unnecessary signaling overhead and power consumption when re-initiating SDT.

[0331] In one possible implementation, the terminal receives an RRC rejection message. If the second timer has not run, the terminal can set a first variable to a first value. A first value indicates that there is a pending RNAU. Optionally, the first variable can take either a first value or a second value. For example, if the first variable indicates whether pendingRNA-Update exists, a first value of true and a second value of false. For a description of the first variable and its first value, please refer to the description of the first variable and its first value in the above implementation of RNAU execution. A specific example is as follows. Figure 14 As shown.

[0332] Please see Figure 14 , Figure 14 This is a flowchart illustrating another control transmission method provided in an embodiment of this application. The method includes, but is not limited to, the following steps:

[0333] S601: The terminal starts the second timer.

[0334] In some embodiments, S601 is an optional step, and S601 and Figure 11 Similar to the S401.

[0335] S602: The terminal starts the first timer.

[0336] In some embodiments, S602 is an optional step, and S602 and Figure 13 Similar to the S501.

[0337] In some embodiments, the execution order of S601 and S602 can be either S601 executing first and S602 executing later, or S602 executing first and S601 executing later.

[0338] S603: The network device sends an RRCReject message to the terminal.

[0339] In some embodiments, S603 is an optional step.

[0340] In some embodiments, when the first timer is running, the terminal receives an RRCReject message and stops the first timer.

[0341] In some embodiments, when a terminal receives an RRCReject message, it is in the RRC INACTIVE state.

[0342] In some embodiments, when a terminal initiates an RRC connection restoration procedure for SDT to a network device, the terminal sends an RRC request message to the network device. The aforementioned RRCReject message is sent by the network device in response to the aforementioned RRC request message. The aforementioned RRC request message is, for example, an RRCResumeRequest message or an RRCResumeRequest1 message, etc., an RRC recovery request message.

[0343] S604: If the second timer is not running, the terminal will set the first variable to the first value.

[0344] In some embodiments, when a terminal receives an RRCReject message, it is in a non-RRC connection state. Optionally, this non-RRC connection state is an RRC INACTIVE state.

[0345] In some embodiments, when the terminal receives an RRCReject message, it considers the SDT process to have failed (rejected) and the terminal is in the RRC INACTIVE state. The terminal still needs to perform periodic RNAU, but since the second timer is not running at this time, the terminal can set the first variable to the first value.

[0346] In some embodiments, if the terminal is in the RRC INACTIVE state after receiving the RRCReject message and the second timer is not running, the terminal can set the first variable to the first value.

[0347] In some embodiments, when a terminal receives an RRCReject message configured with a waittime, the terminal can start a timer T302. Optionally, the UE's RRC connection recovery process is disabled during the execution of timer T302. When timer T302 expires, the disabled RRC connection recovery process of the UE is eased. If the upper layer (such as the NAS layer) does not request the recovery of the RRC connection at this time, the UE can initiate the RRC connection recovery process again. For example, if the upper layer (such as the NAS layer) does not request the recovery of the RRC connection used for data transmission, and the first variable is set to the first value, the UE can continue to initiate the RRC connection recovery process for RNAU.

[0348] In some embodiments, during the SDT process (e.g., before receiving the RRCReject message), if the second timer times out, the terminal can determine whether the first timer is running. If the first timer is running, the terminal does not trigger RNAU and continues the SDT process. After the second timer times out, the terminal receives the RRCReject message, stops the first timer, and the terminal enters the RRC INACTIVE state. If the second timer is not running, the terminal can set the first variable to the first value. Optionally, the second timer not running means that it does not run after the second timer times out.

[0349] In other embodiments, if the terminal receives an RRCReject message and is in the RRC IDLE state, the terminal will not trigger RNAU, nor will it set the first variable to the first value.

[0350] Not limited to Figure 14 The example RRC rejection message may, in other embodiments, be an RRCConnectionReject message or other RRC messages with the same function but not standardized by 3GPP.

[0351] Not limited to Figure 14 As shown in the example, in other embodiments, if the terminal receives an RRC rejection message and the second timer has not run, the terminal can directly execute the RRC connection recovery procedure for RNAU. Specific examples and... Figure 14 Similar, the difference lies in... Figure 14 The first variable is set to a first value to replace the execution of the RRC connection recovery process for RNAU. For example, the RRC layer of the terminal executes the RRC connection recovery process for RNAU. Optionally, if the terminal receives an RRCReject message and the RRCReject message is not configured with a wait time, the terminal executes the RRC connection recovery process for RNAU. For example, the RRC layer of the terminal directly executes the RRC connection recovery process for RNAU.

[0352] In other embodiments, the terminal may first set the first variable to a first value, and then the terminal executes the RRC connection recovery process for RNAU. For example, the terminal's RRC layer directly executes the RRC connection recovery process for RNAU.

[0353] In other embodiments, upon receiving an RRC rejection message, if the second timer has not run, the terminal may start a third timer. When the third timer expires, if the first timer has not run, the terminal executes the RRC connection recovery process for RNAU. Specific examples and... Figure 14 Similar, the difference lies in... Figure 14 The first variable is set to the first value to replace the activation of the third timer. Optionally, the method further includes: when the third timer times out, if the first timer has not run, the terminal executes the RRC connection recovery procedure for RNAU.

[0354] Optionally, the third timer can be the same as the second timer; for example, the duration of the third timer can be equal to the duration of the second timer. For example, the third timer could be T380.

[0355] Optionally, the third timer may differ from the second timer; for example, the duration of the third timer may not be equal to the duration of the second timer. For instance, the duration of the third timer may be shorter than the duration of the second timer, or the duration of the third timer may be in milliseconds or seconds.

[0356] Optionally, during the third timer's operation, the terminal may wait for whether the NAS layer has a data transmission requirement, such as whether the NAS triggers the RRC layer to initiate a connection recovery process. If the NAS layer has a data transmission requirement and triggers the RRC layer to initiate a connection recovery process, the terminal will initiate an RRC connection recovery process for data transmission, but will not execute an RRC connection recovery process for RNAU. The aforementioned RRC connection recovery process for data transmission includes both SDT and non-SDT RRC connection recovery processes.

[0357] In some embodiments,

[0358] 1>else if RRCReject is received in response to an RRCResumeRequest oran RRCResumeRequest1:

[0359] 2>if resume is triggered due to an SDT procedure,and

[0360] 2>if T380 expires:

[0361] 3>set the variable pendingRNA-Update to true.

[0362] In some embodiments, if the terminal receives an RRCReject message in response to an RRCResumeRequest message or an RRCResumeRequest1 message, and if the recovery is triggered based on an SDT procedure and the second timer expires, the terminal can set a first variable to a first value, wherein the terminal can request the aforementioned recovery by sending an RRCResumeRequest message or an RRCResumeRequest1 message. Optionally, the aforementioned recovery is an RRC connection recovery procedure for SDT.

[0363] In one possible implementation, when the first timer times out and the second timer has not run, the terminal can set the first variable to a first value. The first variable setting to the first value indicates that there is an pending RNAU. For an explanation of the first variable and the first value, please refer to the explanation of the first variable and the first value in the above implementation of executing RNAU. A specific example is as follows. Figure 15 As shown.

[0364] Please see Figure 15 , Figure 15 This is a flowchart illustrating another control transmission method provided in an embodiment of this application. The method includes, but is not limited to, the following steps:

[0365] S701: The terminal starts the second timer.

[0366] In some embodiments, S701 is an optional step, and S701 and Figure 11 Similar to the S401.

[0367] S702: The terminal starts the first timer.

[0368] In some embodiments, S702 is an optional step, and S702 and Figure 13 Similar to the S501.

[0369] In some embodiments, the execution order of S701 and S702 can be either S701 executing first and S702 executing later, or S702 executing first and S701 executing later.

[0370] S703: When the first timer times out, if the second timer has not run, the terminal will set the first variable to the first value.

[0371] In some embodiments, after the first timer expires, the terminal is in a non-RRC connected state. Optionally, this non-RRC connected state is an RRC INACTIVE state. In some embodiments, when the terminal is in the RRC INACTIVE state, it initiates an RRC connection recovery process for SDT to the network device and starts the first timer. After the first timer expires, the terminal remains in the RRC INACTIVE state.

[0372] In some embodiments, when the first timer times out and the terminal is in the RRC INACTIVE state, the terminal still needs to perform periodic RNAU. However, since the second timer is not running at this time, the terminal can set the first variable to the first value.

[0373] In some embodiments, if the terminal is in the RRC INACTIVE state after the first timer expires and the second timer is not running, the terminal sets the first variable to the first value.

[0374] In some embodiments, during SDT (such as before the first timer expires), if the second timer expires, the terminal can determine whether the first timer is running. If the first timer is running, the terminal does not trigger RNAU and continues the SDT process. After the second timer expires, if the first timer expires, the terminal is in the RRC INACTIVE state. If the second timer is not running, the terminal can set the first variable to a first value. Optionally, the second timer not running means not running after the second timer expires.

[0375] In other embodiments, if the first timer times out and the terminal is in the RRC IDLE state, the terminal will not trigger RNAU, nor will it set the first variable to the first value.

[0376] Not limited to Figure 15 As illustrated, in some other embodiments, when the first timer times out and the second timer has not run, the terminal can directly execute the RRC connection recovery process for RNAU. Specific examples and... Figure 15 Similar, the difference lies in... Figure 15 The first variable is set to the first value and replaced with the execution of the RRC connection recovery process for RNAU, for example, the RRC layer of the terminal executes the RRC connection recovery process for RNAU.

[0377] In other embodiments, the terminal may first set the first variable to a first value, and then the terminal executes the RRC connection recovery process for RNAU. For example, the terminal's RRC layer directly executes the RRC connection recovery process for RNAU.

[0378] In other embodiments, when the first timer expires and the second timer has not run, the terminal can start a third timer. When the third timer expires and the first timer has not run, the terminal executes the RRC connection recovery process for RNAU. Specific examples and... Figure 15 Similar, the difference lies in... Figure 15 The method replaces setting the first variable to the first value with starting the third timer. Optionally, the method further includes: when the third timer times out, if the first timer has not run, the terminal executes the RRC connection recovery procedure for RNAU.

[0379] Optionally, the third timer can be the same as the second timer; for example, the duration of the third timer can be equal to the duration of the second timer. For example, the third timer could be T380.

[0380] Optionally, the third timer may differ from the second timer; for example, the duration of the third timer may not be equal to the duration of the second timer. For instance, the duration of the third timer may be shorter than the duration of the second timer, or the duration of the third timer may be in milliseconds or seconds.

[0381] Optionally, during the third timer's operation, the terminal may wait for whether the NAS layer has a data transmission requirement, such as whether the NAS triggers the RRC layer to initiate a connection recovery process. If the NAS layer has a data transmission requirement and triggers the RRC layer to initiate a connection recovery process, the terminal will initiate an RRC connection recovery process for data transmission, but will not execute an RRC connection recovery process for RNAU. The aforementioned RRC connection recovery process for data transmission includes both SDT and non-SDT RRC connection recovery processes.

[0382] In one possible implementation, when SIB1 from the second serving cell is received, if the second serving cell belongs to the configured RNA and the second timer is not running, the terminal can set the first variable to a first value. The first variable setting to the first value indicates that there is an pending RNAU. For an explanation of the first variable and the first value, please refer to the explanation of the first variable and the first value in the above implementation of the RNAU execution method. A specific example is as follows. Figure 16 As shown.

[0383] Please see Figure 16 , Figure 16 This is a flowchart illustrating another control transmission method provided in an embodiment of this application. The method includes, but is not limited to, the following steps:

[0384] S801: The terminal starts the second timer.

[0385] In some embodiments, S801 is an optional step, and S801 and Figure 11 Similar to the S401.

[0386] S802: The terminal starts the first timer.

[0387] In some embodiments, S802 is an optional step, and S802 and Figure 13 Similar to the S501.

[0388] In some embodiments, the execution order of S801 and S802 can be either S801 executing first and S802 executing later, or S802 executing first and S801 executing later.

[0389] S803: Cell reselection has occurred in the terminal.

[0390] In some embodiments, S803 is an optional step.

[0391] In some embodiments, during the SDT process between the terminal and the network device, a cell reselection occurs. In some embodiments, when the terminal performs a cell reselection while the first timer is running, the first timer is stopped.

[0392] In some embodiments, when a terminal undergoes cell reselection and switches from a third cell to a fourth cell, the serving cell after the cell reselection is the fourth cell, which will be referred to as the second serving cell. In some embodiments, the second serving cell of the terminal belongs to the configured RNA, which is configured for the terminal by the network device before the cell reselection.

[0393] In some embodiments, after a cell reselection occurs, the terminal receives the SIB1 of the current serving cell and determines a second serving cell based on the SIB1. The SIB1 indicates the second serving cell. In some embodiments, the terminal determines that the second serving cell belongs to a configured RNA based on the SIB1, wherein the RNA was configured for the terminal by the network device before the cell reselection occurred. Specific examples and... Figure 11 Similar to the S502, it will not be described in detail again.

[0394] In some embodiments, after a cell reselection occurs, the terminal is in a non-RRC connected state. Optionally, this non-RRC connected state is an RRC INACTIVE state.

[0395] S804: If the second serving cell belongs to the configured RNA and the second timer is not running, the terminal sets the first variable to the first value.

[0396] In some embodiments, after a cell reselection occurs, the terminal is in a non-RRC connected state. Optionally, this non-RRC connected state is an RRC INACTIVE state. In some embodiments, when the terminal is in the RRC INACTIVE state, it initiates an RRC connection recovery process for SDT to the network device and starts a first timer. If a cell reselection occurs while the first timer is running, the terminal remains in the RRC INACTIVE state.

[0397] In some embodiments, if the terminal is in the RRC INACTIVE state after a cell reselection and the second serving cell belongs to the configured RNA and the second timer is not running, the terminal can set the first variable to the first value.

[0398] In some embodiments, when the terminal is in the RRC INACTIVE state, if the second serving cell belongs to the configured RNA and the second timer is not running, and the terminal cannot perform the SDT procedure in the second serving cell, the terminal can set the first variable to the first value. Optionally, the terminal being unable to perform the SDT procedure in the second serving cell means that the terminal cannot continue the previous SDT procedure in the second serving cell. For example, after a cell reselection, the terminal cannot continue the RRC connection recovery procedure for SDT initiated in S802. Optionally, the terminal being unable to perform the SDT procedure in the second serving cell means that the terminal cannot initiate a new SDT procedure in the second serving cell. For example, after a cell reselection, the terminal cannot continue to initiate a new SDT procedure for the RRC connection recovery procedure for SDT initiated in S802, or cannot initiate a new SDT procedure for newly acquired small data. Optionally, the terminal being unable to perform the SDT procedure in the second serving cell means that the terminal does not have SDT-related configuration information in the second serving cell. For example, the second serving cell does not support SDT. Optionally, the second serving cell not supporting SDT includes the second serving cell not broadcasting the relevant SDT configuration in the system information. For example, the second serving cell does not support RA-SDT and / or CG-SDT.

[0399] In some embodiments, when a cell reselection occurs and the terminal is in the RRC INACTIVE state, the terminal still needs to perform periodic RNAU. However, since the second timer is not running at this time, the terminal can set the first variable to the first value.

[0400] In some embodiments, during SDT (such as before cell reselection), if the second timer times out, the terminal can determine whether the first timer is running. If the first timer is running, the terminal does not trigger RNAU and continues the SDT process. Optionally, if the first timer is running, the terminal can continue the previous SDT process in the second serving cell. Alternatively, if the first timer is running, the terminal can initiate a new RRC connection recovery process for SDT in the second serving cell. After the second timer times out, if cell reselection occurs, the first timer stops, and the terminal enters the RRC INACTIVE state. If the second timer does not run, the terminal can set the first variable to a first value. Optionally, if the second timer does not run, it does not run after the second timer times out.

[0401] In some embodiments, after a cell reselection occurs, the terminal is in the RRC IDLE state, so the terminal does not trigger the RNA or set the first variable to the first value. In other embodiments, after a cell reselection occurs, the terminal can perform the SDT process in the second serving cell, so the terminal does not trigger the RNA or set the first variable to the first value.

[0402] Not limited to Figure 16 As shown in the example, in some other embodiments, when SIB1 of the second serving cell is received, if the second serving cell belongs to the configured RNA and the second timer is not running, the terminal can directly execute the RRC connection recovery process for RNAU. Specific examples and... Figure 16 Similar, the difference lies in... Figure 16 The first variable is set to the first value and replaced with the execution of the RRC connection recovery process for RNAU, for example, the RRC layer of the terminal executes the RRC connection recovery process for RNAU.

[0403] In other embodiments, the terminal may first set the first variable to a first value, and then the terminal executes the RRC connection recovery process for RNAU. For example, the terminal's RRC layer directly executes the RRC connection recovery process for RNAU.

[0404] In other embodiments, when SIB1 of the second serving cell is received, if the second serving cell belongs to the configured RNA and the second timer is not running, the terminal starts the third timer. Specific examples and... Figure 16 Similar, the difference lies in... Figure 16 The method replaces setting the first variable to the first value with starting the third timer. Optionally, the method further includes: when the third timer times out, if the first timer has not run, the terminal executes the RRC connection recovery procedure for RNAU.

[0405] Optionally, the third timer can be the same as the second timer; for example, the duration of the third timer can be equal to the duration of the second timer. For example, the third timer could be T380.

[0406] Optionally, the third timer may differ from the second timer; for example, the duration of the third timer may not be equal to the duration of the second timer. For instance, the duration of the third timer may be shorter than the duration of the second timer, or the duration of the third timer may be in milliseconds or seconds.

[0407] Optionally, during the third timer's operation, the terminal may wait for whether the NAS layer has a data transmission requirement, such as whether the NAS triggers the RRC layer to initiate a connection recovery process. If the NAS layer has a data transmission requirement and triggers the RRC layer to initiate a connection recovery process, the terminal will initiate an RRC connection recovery process for data transmission, but will not execute an RRC connection recovery process for RNAU. The aforementioned RRC connection recovery process for data transmission includes both SDT and non-SDT RRC connection recovery processes.

[0408] In some embodiments, 1> if cell reselection occurs while T319, T302, or T3XX is running:

[0409] 2>if T380 expires during an SDT procedure or has expired during an SDT procedure:

[0410] 3>set the variable pendingRNA-Update to true.

[0411] In some embodiments, if a cell reselection occurs during the operation of timer T319, timer T302, or the first timer T3XX, and if the second timer T380 times out or has already timed out during the SDT process, the terminal can set the variable pendingRNA-Update to true.

[0412] In one possible implementation, if the terminal's integrity check fails and the second timer does not run, the terminal can set the first variable to a first value. The first variable setting to a first value indicates that an RNAU is pending. For an explanation of the first variable and the first value, please refer to the explanation of the first variable and the first value in the above implementation of executing the RNAU. A specific example is as follows. Figure 17 As shown.

[0413] Please see Figure 17 , Figure 17This is a flowchart illustrating another control transmission method provided in an embodiment of this application. The method includes, but is not limited to, the following steps:

[0414] S901: The terminal starts the second timer.

[0415] In some embodiments, S901 is an optional step, and S901 and Figure 11 Similar to the S401.

[0416] S902: The terminal starts the first timer.

[0417] In some embodiments, S902 is an optional step, and S902 and Figure 13 Similar to the S501.

[0418] In some embodiments, the execution order of S901 and S902 can be either S901 executing first and S902 executing later, or S902 executing first and S901 executing later.

[0419] S903: When the terminal's integrity check fails, if the second timer does not run, the terminal will set the first variable to the first value.

[0420] In some embodiments, when the first timer runs, the integrity check of the terminal fails. In some embodiments, the integrity check failure of the terminal occurs when the terminal's RRC layer receives an indication of integrity check failure from the underlying layer of the RRC layer, such as the PDCP layer.

[0421] In some embodiments, after the terminal's integrity verification fails, the terminal is in the RRC INACTIVE state. In some embodiments, while in the RRC INACTIVE state, the terminal initiates an RRC connection recovery process for SDT to the network device and starts a first timer. If the terminal's integrity verification fails while the first timer is running, the terminal remains in the RRC INACTIVE state.

[0422] In some embodiments, if the integrity check of the terminal fails and the terminal is in the RRC INACTIVE state, the terminal still needs to perform periodic RNAU. However, since the second timer is not running at this time, the terminal can set the first variable to the first value.

[0423] In some embodiments, during the SDT process (e.g., before the terminal's integrity check fails), if the second timer times out, the terminal can determine whether the first timer is running. If the first timer is running, the terminal does not trigger RNAU and continues the SDT process. After the second timer times out, if the terminal's integrity check fails, the terminal is in the RRC INACTIVE state. If the second timer is not running, the terminal can set the first variable to a first value. Optionally, the second timer not running means not running after the second timer times out.

[0424] In other embodiments, if the terminal's integrity check fails and the terminal is in the RRC IDLE state, the terminal will not trigger RNAU, nor will it set the first variable to the first value.

[0425] Not limited to Figure 17 As illustrated in the examples, in other embodiments, if the terminal's integrity check fails and the second timer does not run, the terminal can directly execute the RRC connection recovery process for RNAU. Specific examples and... Figure 17 Similar, the difference lies in... Figure 17 The first variable is set to the first value and replaced with the execution of the RRC connection recovery process for RNAU, for example, the RRC layer of the terminal executes the RRC connection recovery process for RNAU.

[0426] In other embodiments, the terminal may first set the first variable to a first value, and then the terminal executes the RRC connection recovery process for RNAU. For example, the terminal's RRC layer directly executes the RRC connection recovery process for RNAU.

[0427] In other embodiments, if the terminal's integrity check fails and the second timer does not run, the terminal can start a third timer. When the third timer expires and the first timer does not run, the terminal executes the RRC connection recovery process for RNAU. Specific examples and... Figure 17 Similar, the difference lies in... Figure 17 The method replaces setting the first variable to the first value with starting the third timer. Optionally, the method further includes: when the third timer times out, if the first timer has not run, the terminal executes the RRC connection recovery procedure for RNAU.

[0428] Optionally, the third timer can be the same as the second timer; for example, the duration of the third timer can be equal to the duration of the second timer. For example, the third timer could be T380.

[0429] Optionally, the third timer may differ from the second timer; for example, the duration of the third timer may not be equal to the duration of the second timer. For instance, the duration of the third timer may be shorter than the duration of the second timer, or the duration of the third timer may be in milliseconds or seconds.

[0430] Optionally, during the third timer's operation, the terminal may wait for whether the NAS layer has a data transmission requirement, such as whether the NAS triggers the RRC layer to initiate a connection recovery process. If the NAS layer has a data transmission requirement and triggers the RRC layer to initiate a connection recovery process, the terminal will initiate an RRC connection recovery process for data transmission, but will not execute an RRC connection recovery process for RNAU. The aforementioned RRC connection recovery process for data transmission includes both SDT and non-SDT RRC connection recovery processes.

[0431] Understandably, this application will not trigger RNAU during the SDT process. During SDT, the network device can obtain the RNA where the terminal is located. Not executing RNAU will not only not affect the network device's acquisition of the terminal's status, but also avoid affecting the small packet data transmitted during the SDT process.

[0432] Furthermore, in cases where SDT terminates abnormally (e.g., receiving the fourth RRC response message, cell reselection, the first timer timeout, or the terminal's integrity verification fails), if the second timer does not run (e.g., it does not run after timeout), the terminal can set the first variable to the first value so that the UE can continue to periodically trigger RNAU without affecting the normal execution of RNAU.

[0433] In one possible implementation, if the first variable is set to a first value during the SDT process, the terminal can perform an RRC connection recovery procedure for RNAU. In some embodiments, if the first variable is set to a first value during the SDT process, and the upper layer (e.g., the NAS layer) does not request the recovery of the RRC connection, the terminal performs an RRC connection recovery procedure for RNAU. In some embodiments, if the terminal's Access Category 2 or Access Category 8 block is mitigated, and the upper layer (e.g., the NAS layer) does not request the recovery of the RRC connection, and the first variable is set to a first value, the terminal performs an RRC connection recovery procedure for RNAU. In some embodiments, if the terminal's Access Category block is mitigated during the SDT process, and the upper layer (e.g., the NAS layer) does not request the recovery of the RRC connection, and the first variable is set to a first value, the terminal performs an RRC connection recovery procedure for RNAU. In some embodiments, if the access block is mitigated and the upper layer (e.g., the NAS layer) does not request the RRC layer to perform RRC connection recovery, and if the first variable is the first value, the terminal can perform an RRC connection recovery procedure for RNAU.

[0434] Please see Figure 18 , Figure 18 Another timing diagram is shown as an example.

[0435] As Figure 18 shown, the horizontal axis is the time axis (t). At the third moment t3, the second timer is started (for example, receiving the first RRC response message). At the fourth moment t4, the first timer is started (for example, sending an RRC request message). At the fifth moment t5, the second timer expires. At the sixth moment t6, the first timer stops or expires, where t3 < t4 < t5 < t6. The second timer runs between the third moment and the fifth moment, and the first timer runs between the fourth moment and the sixth moment. Between the fourth moment and the sixth moment, the terminal performs the SDT process. At the fifth moment, during the SDT process of the terminal, when the second timer expires, the terminal does not trigger RNAU, that is, when the second timer expires and the first timer is running, the terminal does not trigger RNAU.

[0436] In some embodiments, at the sixth moment, the terminal performs cell reselection, the first timer stops, and the terminal is in the RRC INACTIVE state. If the serving cell of the terminal after cell reselection does not belong to the configured RNA, and the terminal cannot perform the SDT process in the serving cell, then the terminal can trigger RNAU. Optionally, triggering RNAU is to perform an RRC connection restoration process for RNAU. For details, see the Figure 13 description above.

[0437] In some other embodiments, at the sixth moment, the terminal receives the fourth RRC response message, the first timer stops, and the terminal is in the RRC INACTIVE state. If the second timer is not running, then the terminal can trigger RNAU. Optionally, triggering RNAU is to set the first variable to the first value. For details, see the Figure 14 description above.

[0438] In some other embodiments, at the sixth moment, the first timer expires, and the terminal is in the RRC INACTIVE state. If the second timer is not running, then the terminal can trigger RNAU. Optionally, triggering RNAU is to set the first variable to the first value. For details, see the Figure 15 description above.

[0439] In some other embodiments, at the sixth moment, the terminal performs cell reselection, the first timer stops, and the terminal is in the RRC INACTIVE state. If the serving cell of the terminal after cell reselection belongs to the configured RNA, the terminal cannot perform the SDT process in the serving cell, and at this time the second timer is not running, then the terminal can trigger RNAU. Optionally, triggering RNAU is to set the first variable to the first value. For details, see the Figure 16 description above.

[0440] In other embodiments, at the sixth time step, if the terminal's integrity check fails, the first timer stops, and the terminal enters the RRC INACTIVE state. If the second timer does not run, the terminal can trigger RNAU. Optionally, triggering RNAU can set the first variable to a first value, as detailed above. Figure 17 Explanation.

[0441] In one possible implementation, the second timer can be stopped when the terminal performs the SDT process, as shown in the following example. Figure 19 As shown.

[0442] Please see Figure 19 , Figure 19 This is a flowchart illustrating another control transmission method provided in an embodiment of this application. The method includes, but is not limited to, the following steps:

[0443] S1001: The terminal sends an RRC request message to the network device.

[0444] In some embodiments, S1001 is an optional step.

[0445] In some embodiments, when a terminal has a need for SDT, it can initiate an RRC connection recovery process for SDT. The RRC connection recovery process may include the terminal sending an RRC request message to the network device based on SDT.

[0446] In some embodiments, when the terminal requires SDT, it can initiate an RRC connection recovery process for 4-step SDT, which can be referred to above. Figures 5-6 The process shown in the diagram involves the terminal sending an RRC request message during the RRC connection restoration process based on a 4-step SDT, and this RRC request message can be in msg3.

[0447] In some embodiments, when the terminal requires SDT, it can initiate an RRC connection recovery process for 2-step SDT, which can be referred to above. Figures 7-8 The process shown in the diagram involves the terminal sending an RRC request message during the RRC connection recovery process based on a 2-step SDT. This RRC request message can be sent in msgA.

[0448] In some embodiments, when the terminal requires SDT, it can initiate an RRC connection recovery process for CG-SDT, which can be referred to above. Figures 9-10 The process shown in the diagram involves the terminal sending RRC request messages based on CG-SDT during the RRC connection restoration process.

[0449] In some embodiments, when a terminal sends an RRC request message to a network device, it also sends uplink small packet data, as shown in the example above. Figure 5 , Figure 7 , Figure 9 The process is shown below.

[0450] S1002: The network device sends the first response message to the terminal.

[0451] In some embodiments, S1002 is an optional step.

[0452] In some embodiments, when a network device receives an RRC request message sent by a terminal, it can send a first response message to the terminal. In some embodiments, when a network device receives an RRC request message and uplink small packet data sent by a terminal, it can send a first response message to the terminal.

[0453] In some embodiments, when a terminal initiates RA-SDT, the network device receives an RRC request message sent by the terminal based on RA-SDT and can send a first response message to the terminal. Optionally, the first response message can indicate successful contention resolution; alternatively, the first response message can indicate successful completion of the random access procedure; alternatively, upon receiving the first response message, the terminal determines that the contention resolution was successful; alternatively, upon receiving the first response message, the terminal determines that the random access procedure was successfully completed; alternatively, the first response message is... Figures 5-8 The contention resolution message shown.

[0454] In some embodiments, the terminal initiates CG-SDT, and the network device receives the RRC request message sent by the terminal based on CG-SDT. The network device can then send a first response message to the terminal. Optionally, the first response message can be for the RRC request message and / or uplink small packet data sent in S1001. Optionally, the first response message can indicate that the RRC request message was successfully sent. Optionally, the first response message can indicate that the uplink small packet data was successfully sent. Optionally, the first response message is an uplink small packet data transmission. Figures 9-10 The feedback response message shown can optionally include downlink control information (DCI) for scheduled retransmission, or DCI for scheduled new transmission.

[0455] S1003: The terminal's lower layer instructs the upper layer to provide the first information.

[0456] In some embodiments, S1003 is an optional step.

[0457] Specifically, a terminal may include multiple layers; see above for specific examples. Figures 2-3The user plane protocol stack or control plane protocol stack shown includes the layers. It is understood that "bottom layer" and "upper layer" in S1003 are relative concepts. In some embodiments, the bottom layer of the terminal in S1003 is the first layer, which is a layer in the user plane protocol stack or control plane protocol stack. In some embodiments, the first layer is the layer that receives the first response message sent by the network device. In some embodiments, the upper layer in S1003 is the second layer, which is a layer above the first layer.

[0458] For example, the first layer is the MAC layer, and the second layer is the RRC layer.

[0459] For example, the first layer is the physical layer, and the second layer is the MAC layer.

[0460] For example, the first layer is the physical layer, and the second layer is the RRC layer.

[0461] S1004: The terminal stops the second timer.

[0462] In some embodiments, the terminal's third layer receives first information from the lower layer of the third layer and stops the second timer. Optionally, the third layer is the RRC layer, the lower layer of the third layer is the MAC layer, or the lower layer of the third layer is the physical layer.

[0463] In some embodiments, during the RA-SDT process, the terminal's MAC layer receives a first response message sent by the network device. The MAC layer then indicates first information to the RRC layer above the MAC layer. Optionally, the first information indicates successful contention resolution; alternatively, the first indication information indicates successful completion of the random access procedure. Upon receiving the first information indicated by the MAC layer, the RRC layer stops the second timer. Optionally, in S1003, the lower layer is the MAC layer and the upper layer is the RRC layer; in S1004, the RRC layer stops the second timer.

[0464] In some embodiments, during the CG-SDT process, the terminal's MAC layer receives a first response message sent by the network device. The MAC layer then indicates first information to the RRC layer above the MAC layer. The first information indicates that the RRC request message and / or uplink small packet data were successfully sent. Upon receiving the first information indicated by the MAC layer, the RRC layer stops the second timer. Optionally, in S1003, the lower layer is the MAC layer and the upper layer is the RRC layer, and in S1004, the RRC layer stops the second timer.

[0465] In some embodiments, during the CG-SDT process, the terminal's physical layer receives a first response message sent by the network device. The physical layer then indicates first information to the RRC layer above the physical layer. The first information indicates that the RRC request message and / or uplink small packet data were successfully sent. Upon receiving the first information indicated by the physical layer, the RRC layer stops the second timer. Optionally, in S1003, the lower layer is the physical layer and the upper layer is the RRC layer, and in S1004, the RRC layer stops the second timer.

[0466] In some embodiments, during the CG-SDT process, the terminal's physical layer receives a first response message sent by the network device. The physical layer then indicates second information to the MAC layer above the physical layer. The second information indicates that the RRC request message and / or uplink small packet data were successfully sent. Upon receiving the second information from the physical layer, the MAC layer indicates first information to the RRC layer above the MAC layer. The first information indicates that the RRC request message and / or uplink small packet data were successfully sent. Upon receiving the first information from the MAC layer, the RRC layer stops the second timer. Optionally, in S1003, the lower layer is the MAC layer and the upper layer is the RRC layer; in S1004, the RRC layer stops the second timer.

[0467] In some embodiments, the second timer is enabled before the terminal stops it. For example, the terminal enables the second timer before initiating the RRC connection recovery process for SDT (such as S1001).

[0468] In some embodiments, after the terminal stops the second timer, subsequent transmission can be performed based on this SDT process, as detailed above. Figures 5-10 The description of subsequent transmission is as follows: The second timer has been stopped and will not time out, therefore RNAU will not be triggered, and thus the transmission of smalldata during SDT will not be affected.

[0469] In some embodiments, after the terminal stops the second timer, it can receive an RRC response message sent by the network device, as detailed above. Figures 5-10 Description of RRC response messages. In some embodiments, after the terminal stops the second timer, upon receiving a first RRC response message from the network device, such as an RRC Resume message, an RRC Resume with suspend config message, or other RRC messages with the same function but not standardized by 3GPP, the terminal can start the second timer.

[0470] It is understood that the circumstances under which the second timer is activated as described in the above embodiments may include various situations. Two such situations are illustrated below:

[0471] Scenario 1: When the terminal performs SDT, it receives a first RRC response message, stops the first timer, and starts a second timer. For example, when the terminal has an SDT requirement, it initiates an RRC connection recovery process for SDT, starting the first timer. Then, when the second timer expires, but the first timer is running, the terminal does not trigger RNAU and continues SDT. Finally, the terminal receives the first RRC response message, considers the SDT successful, stops the first timer, remains in a non-RRC connection state, and, upon receiving the first RRC response message, starts the second timer so that RNAU can be periodically triggered subsequently.

[0472] Scenario 2: When the terminal performs SDT, it receives a fifth RRC response message, stops the first timer, and then starts a second timer upon receiving a subsequent first RRC response message. The fifth RRC response message can be, for example, an RRCResume message, an RRCSetup message, or other RRC messages with the same function but not standardized by 3GPP. For example, when the terminal has an SDT requirement, it initiates an RRC connection recovery process for SDT, starting the first timer. Then, when the second timer expires but the first timer is running, the terminal does not trigger RNAU and continues SDT. Next, the terminal receives the fifth RRC response message, considers the SDT successful, stops the first timer, and can transition from the non-RRC connected state to the RRC CONNECTED state. Subsequently, when the terminal receives the first RRC response message, it transitions from the RRC CONNECTED state to the non-RRC connected state and starts the second timer so that it can continue to periodically trigger RNAU.

[0473] In one possible implementation, the terminal receives an RRC rejection message. If the second timer has not run, the terminal can set the first variable to a first value. Specific examples and... Figure 14 Similar, the difference lies in Figure 14 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0474] In one possible implementation, the terminal receives an RRC rejection message. If the second timer has not run, the terminal can directly execute the RRC connection recovery procedure for RNAU. Specific examples and... Figure 14 Similarly, the difference is that S604 can be changed to: if the second timer does not run, execute the RRC connection recovery process for RNAU, and Figure 14 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0475] In one possible implementation, the terminal receives an RRC rejection message. If the second timer has not run, the terminal can start a third timer. When the third timer expires, if the first timer has not run, the terminal executes the RRC connection recovery procedure for RNAU. Specific examples and... Figure 14 Similarly, the difference is that S604 can be changed to: if the second timer does not run, start the third timer. After S604, the method also includes: when the third timer times out, if the first timer does not run, the terminal executes the RRC connection recovery process for RNAU, and Figure 14 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0476] In one possible implementation, when the first timer times out and the second timer has not run, the terminal can set the first variable to its first value. Specific examples and... Figure 15 Similar, the difference lies in Figure 15 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0477] In one possible implementation, if the second timer has not run when the first timer times out, the terminal can directly execute the RRC connection recovery procedure for RNAU. Specific examples and... Figure 15 Similarly, the difference is that S703 can be changed to: when the first timer times out, if the second timer has not run, execute the RRC connection recovery process for RNAU, and Figure 15 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0478] In one possible implementation, when the first timer expires and the second timer has not run, the terminal can start a third timer. When the third timer expires and the first timer has not run, the terminal executes the RRC connection recovery process for RNAU. Specific examples and... Figure 15 Similarly, the difference is that S703 can be changed to: when the first timer times out, if the second timer has not run, start the third timer. After S703, the method also includes: when the third timer times out, if the first timer has not run, the terminal executes the RRC connection recovery process for RNAU, and... Figure 15 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0479] In one possible implementation, when SIB1 of the second serving cell is received, if the second serving cell belongs to the configured RNA and the second timer is not running, the terminal can set the first variable to the first value. Specific examples and... Figure 16 Similar, the difference lies in Figure 16 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0480] In one possible implementation, when SIB1 of the second serving cell is received, if the second serving cell belongs to the configured RNA and the second timer is not running, the terminal can directly execute the RRC connection recovery procedure for RNAU. Specific examples and... Figure 15 Similarly, the difference is that S804 can be changed to: if the second serving cell belongs to the configured RNA and the second timer is not running, execute the RRC connection recovery procedure for RNAU, and Figure 16 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0481] In one possible implementation, when SIB1 of the second serving cell is received, if the second serving cell belongs to the configured RNA and the second timer is not running, the terminal starts the third timer. Specific examples and... Figure 16 Similarly, the difference is that S804 can be changed to: if the second serving cell belongs to the configured RNA and the second timer is not running, start the third timer. After S804, the method also includes: when the third timer times out, if the first timer is not running, the terminal executes the RRC connection recovery process for the RNAU, and... Figure 16 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0482] In one possible implementation, if the terminal's integrity check fails and the second timer has not run, the terminal can set the first variable to its first value. Specific examples and... Figure 17 Similar, the difference lies in Figure 17 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0483] In one possible implementation, if the terminal's integrity check fails and the second timer has not run, the terminal can directly execute the RRC connection recovery process for RNAU. Specific examples and... Figure 17Similarly, the difference is that S903 can be changed to: when the integrity check fails and the second timer does not run, execute the RRC connection recovery process for RNAU, and Figure 17 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0484] In one possible implementation, if the terminal's integrity check fails and the second timer has not run, the terminal can start a third timer. Specific examples and... Figure 17 Similarly, the difference is that S903 can be changed to: when integrity verification fails and the second timer does not run, start the third timer. After S903, the method also includes: when the third timer times out, if the first timer has not run, the terminal executes the RRC connection recovery process for RNAU, and... Figure 17 If the second timer times out, it needs to be replaced with a second timer stop. For instructions on stopping the second timer, please refer to the above. Figure 19 .

[0485] In one possible implementation, after the terminal sets the first variable to the first value during the SDT process, if the access ban is mitigated and the non-access NAS layer does not request the RRC layer to perform RRC connection restoration, and if the first variable is the first value, the terminal can execute the RRC connection restoration process for RNAU.

[0486] Understandably, the SDT process in this application (e.g., above) Figures 5-10 The SDT process shown may include the RRC connection recovery process for SDT described above, optionally wherein the resumeCause IE in the sent RRC request message is mo-data. The RNAU in this application (e.g., the implementation of RNAU described above) may include the RRC connection recovery process for RNAU described above, optionally wherein the resumeCause IE in the sent RRC request message is rna-Update.

[0487] Not limited to the cases listed above, in other embodiments, the UE in the RRC IDLE state may need to perform RNAU. The specific implementation is similar to the implementation of the UE in the RRC INACTIVE state, but the description may be different. For example, the RRC connection recovery process for RNAU can be replaced by the RRC connection establishment process for RNAU.

[0488] Not limited to SIB1 in the above example, in other embodiments, the terminal may receive other messages and determine whether the serving cell belongs to the configured RNA based on these messages. For example, the terminal may read the cell identifier from the message and determine whether the read cell identifier belongs to the cell identifier included in the cell list configured by the base station for the UE in the RAN-NotificationAreaInfo IE. Another example is the terminal may read the cell's TAC from the message and determine whether the read TAC belongs to the TAC included in the RAN area list configured by the base station for the UE in the RAN-NotificationAreaInfo IE. This application does not limit the method for determining whether the serving cell belongs to the configured RNA.

[0489] In some embodiments, a UE in the RRCINACTIVE state needs to trigger an RRC connection recovery procedure for RNAU after a T380 timeout or after receiving SIB1 in a cell outside the UE's current RNA. However, a UE performing SDT data transmission does not actually need to perform RNAU because the network settings can know the UE's cell location. Therefore, triggering RNAU during SDT should be avoided.

[0490] In some embodiments, T380 is stopped during the SDT process. For example, after the SDT process begins, the UE stops T380 when it receives a first response message corresponding to the UE's RRC request message from the network device. For example, the UE stops T380 when it receives a contention resolution MAC CE for RA-SDT, or when it receives an ACK in response to an RRC Resume Request sent via CG-SDT.

[0491] In some embodiments, an additional condition is introduced: RNAU is only triggered if T380 times out when the SDT failure detection timer is not running (i.e., the first timer is not running). The SDT failure detection timer starts when the UE initiates the RRC connection recovery procedure for SDT; that is, the UE is performing the SDT procedure while the SDT failure detection timer is running. Therefore, to avoid periodic RNAU triggered by T380 timeout, an additional condition can be added to the current conditions for triggering periodic RNAU.

[0492] It is understood that the communication system architecture and business scenarios described in this application are for the purpose of more clearly illustrating the technical solutions of this application, and do not constitute a limitation on the technical solutions provided in this application. As those skilled in the art will know, with the evolution of communication system architecture and the emergence of new business scenarios, the technical solutions provided in this application are also applicable to similar technical problems.

[0493] Those skilled in the art will understand that implementing all or part of the processes in the methods of the above embodiments can be accomplished by a computer program using computer program-related hardware. This computer program can be stored in a computer-readable storage medium, and when executed, it can include the processes described in the above method embodiments. The aforementioned storage medium includes various media capable of storing computer program code, such as read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A communication method, characterized in that, The method, applied to a terminal or a chip in a terminal in a non-Radio Resource Control (RRC) connected state, includes: When the first preset condition is met, the RRC connection recovery procedure for the notification area update RNAU based on the radio access network is executed; wherein, The first preset condition includes the second timer timing out and the small packet data transmission SDT process not being performed; or, The first preset condition includes that the terminal receives the system information block SIB1 of the first serving cell, the first serving cell does not belong to the configured notification area (RNA) based on the radio access network, and the SDT process has not been performed. The second timer is activated when the terminal receives an RRC release message that includes the duration of the second timer.

2. The method as described in claim 1, characterized in that, The first preset condition includes the second timer timing out and the small packet data transmission SDT process not being performed, including: the first preset condition includes the second timer timing out and the first timer not running; The first timer is activated when the terminal initiates an RRC connection recovery process for SDT.

3. The method as described in claim 1, characterized in that, The first preset condition includes the terminal receiving the system information block SIB1 of the first serving cell, the first serving cell not belonging to the configured notification area (RNA) based on the radio access network, and the SDT process not being performed, including: the first preset condition includes the terminal receiving the SIB1 of the first serving cell, and the first timer not running; The first timer is activated when the terminal initiates an RRC connection recovery process for SDT.

4. The method as described in claim 1, characterized in that, The method further includes: If an RRC rejection message is received while the first timer is running, the first timer is stopped, wherein the first timer is started when the terminal initiates an RRC connection recovery process for SDT; If the second timer is not running, the first variable is set to the first value, and the first variable being the first value indicates that there is an pending RNA update process.

5. The method as described in claim 2 or 3, characterized in that, The method further includes: If an RRC rejection message is received while the first timer is running, the first timer is stopped. If the second timer does not run, the RRC ligation recovery process for RNAU is executed.

6. The method as described in claim 2 or 3, characterized in that, The method further includes: If an RRC rejection message is received while the first timer is running, the first timer is stopped. If the second timer is not running, start the third timer; If the first timer has not run when the third timer times out, the RRC connection recovery process for RNAU is executed.

7. The method as described in claim 2 or 3, characterized in that, The method further includes: When the first timer times out, if the second timer has not run, the first variable is set to a first value, and the first variable being the first value indicates that there is an pending RNA update process.

8. The method as described in claim 2 or 3, characterized in that, The method further includes: If the second timer does not run when the first timer times out, the RRC connection recovery process for RNAU is executed.

9. The method as described in claim 2 or 3, characterized in that, The method further includes: If the first timer times out and the second timer has not run, the third timer will be started. If the first timer has not run when the third timer times out, the RRC connection recovery process for RNAU is executed.

10. The method as described in claim 7, characterized in that, The non-radio resource control (RRC) connection state is the RRC inactive state; after the first timer expires, the terminal is in the RRC inactive state.

11. The method as described in claim 2 or 3, characterized in that, The method further includes: If a cell reselection occurs while the first timer is running, the first timer is stopped. Receive SIB1 of the second serving cell, where the second serving cell is the serving cell after the terminal has undergone cell reselection; When SIB1 of the second serving cell is received, if the second serving cell belongs to the configured RNA and the second timer is not running, the first variable is set to the first value, and the first variable being the first value indicates that there is an pending RNA update process.

12. The method as described in claim 2 or 3, characterized in that, The method further includes: If a cell reselection occurs while the first timer is running, the first timer is stopped. Receive SIB1 of the second serving cell, where the second serving cell is the serving cell after the terminal has undergone cell reselection; When SIB1 of the second serving cell is received, if the second serving cell belongs to the configured RNA and the second timer is not running, the RRC connection recovery process for RNAU is executed.

13. The method as described in claim 2 or 3, characterized in that, The method further includes: If a cell reselection occurs while the first timer is running, the first timer is stopped. Receive SIB1 of the second serving cell, where the second serving cell is the serving cell after the terminal has undergone cell reselection; When SIB1 of the second serving cell is received, if the second serving cell belongs to the configured RNA and the second timer is not running, the third timer is started; If the first timer has not run when the third timer times out, the RRC connection recovery process for RNAU is executed.

14. The method as described in claim 11, characterized in that, The non-Radio Resource Control (RRC) connected state is the RRC inactive state; after the terminal undergoes cell reselection, the terminal is in the RRC inactive state.

15. The method as described in claim 4, characterized in that, After setting the first variable to a first value, the method further includes: If the access ban is mitigated and the non-access NAS layer does not request the RRC layer to restore the RRC connection, and if the first variable is the first value, the RRC connection restoration process for RNAU is executed.

16. The method according to any one of claims 1-3, characterized in that, The non-radio resource control (RRC) connection state is the RRC inactive state.

17. The method as described in claim 15, characterized in that, The non-radio resource control (RRC) connection state is the RRC inactive state.

18. The method as described in claim 4, characterized in that, The second timer is not running, including: the second timer timed out.

19. A communication device, characterized in that, It includes a transceiver, a processor, and a memory, the memory storing a computer program that, when run by the processor, causes the method as described in any one of claims 1-18 to be performed.

20. A computer storage medium, characterized in that, The computer storage medium stores a computer program that, when run, causes the method as described in any one of claims 1-18 to be performed.

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