Transmission control method and related device

Abstract

An embodiment of the present application provides a transmission control method and a related device. The method is applied to a terminal in a non-radio resource control (RRC) connected state, and includes the following: performing an RRC connection resumption procedure for a radio access network-based notification area update (RNAU) when a first preset condition is met, the first preset condition includes that a second timer expires and the first timer is not running, or the first preset condition includes that the terminal receives a system information block (SIB1) of a serving cell, the serving cell does not belong to a configured radio access network-based notification area, and the first timer is not running, the first timer is started when the terminal initiates an RRC connection resumption procedure for a small data transmission (SDT), and the second timer is started when the terminal receives an RRC release message including a duration of the second timer. In the present application, the triggering of RNAU in the SDT procedure can be prevented, thereby avoiding an impact on small data transmission and avoiding unnecessary power consumption and signaling overhead.

Description

[Technical field]

[0001] The present application relates to the field of communication technologies, and in particular to a data transmission method and related apparatus. [Background technology]

[0002] This application claims priority to Chinese Patent Application No. 202110822924.X, entitled "Communication Method, Terminal, and Network Equipment," filed with the State Intellectual Property Office of China on July 21, 2021, and Chinese Patent Application No. 202110897870.3, entitled "Transmission Control Method and Related Apparatus," filed with the State Intellectual Property Office of China on August 5, 2021, both of which are incorporated by reference in their entireties herein.

[0003] [background] In a communication system, a communication protocol stack between a terminal and a network device may include a radio resource control (RRC) layer. Currently, there are three RRC states of a terminal: an RRC IDLE state, an RRC INACTIVE state, and an RRC CONNECTED state. A terminal in an RRC INACTIVE state may perform small data transmission between a network device and the terminal through an RRC connection resumption procedure, which may be referred to as a small data transmission (SDT). When a terminal is in an RRC INACTIVE state, a radio access network (RAN) may manage a RAN-based notification area (RNA). For example, the terminal may trigger an RNA update (RNAU) and perform an RRC connection resumption procedure for the RNAU to inform the network device of the RNA where the terminal is currently located.

[0004] When the terminal executes SDT, the execution of RNAU may be triggered. In this case, the terminal may stop the currently executing SDT and execute RNAU, which affects the transmission of small data. For example, if the terminal then starts SDT again, the transmission delay increases, and power consumption and signaling overhead also increase. Summary of the Invention

[0005] The embodiments of the present application disclose a transmission control method and related apparatus to avoid impact on small data transmission and to avoid unnecessary power consumption and signaling overhead.

[0006] According to a first aspect, an embodiment of the present application provides a transmission control method applied to a terminal in a non-radio resource control (RRC) connected state, the method including: performing an RRC connection resumption procedure for a radio access network based notification area update (RNAU) when a first preset condition is met, the first preset condition including that a second timer expires and the first timer is not running, or the first preset condition including that the terminal receives a system information block (SIB1) of a first serving cell, the first serving cell does not belong to a configured radio access network based notification area (RNA) and the first timer is not running, the first timer is started when the terminal initiates an RRC connection resumption procedure for a small data transmission (SDT), and the second timer is started when the terminal receives an RRC release message including a duration of the second timer.

[0007] In some embodiments, the RRC connection resume procedure for an RNAU includes sending an RRC request message, where a resume cause information element, resumeCause IE, in the RRC request message is an RNA update.

[0008] For example, the second timer is T380.

[0009] In the present application, if the first timer is not running (in other words, if the SDT procedure is being performed), RNAU is not executed. When the SDT is executed, the network equipment can obtain the RNA in which the terminal is located. Not executing RNAU can avoid an impact on small data transmitted in the SDT procedure without affecting the acquisition of the terminal status by the network equipment, for example, avoiding an increase in transmission delay, and avoiding unnecessary signaling overhead and power consumption that would be increased by subsequently resuming SDT.

[0010] In a possible implementation, the first timer not running means that the first timer is not started.

[0011] In some embodiments, the first timer not being started indicates that there is no requirement for an SDT.

[0012] In a possible implementation, before performing a radio resource control (RRC connection resumption) procedure for a radio access network-based notification area update (RNAU), when a first preset condition is met, the method further includes: starting an RRC connection resumption procedure for an SDT, starting a first timer; and stopping the first timer when cell reselection occurs, where the first preset condition is that the serving cell of the terminal does not belong to the configured RNA without the first timer being running, and that the first timer is stopped without the first timer being running, and the serving cell of the terminal is a serving cell obtained through cell reselection occurring on the terminal.

[0013] In some embodiments, the RRC connection resume procedure is for SDT includes sending an RRC request message, where a resumeCause IE in the RRC request message is mo-data.

[0014] In a possible implementation, the first preset condition further includes: the terminal is in an RRC inactive state, and / or the terminal is unable to perform an SDT procedure in the serving cell.

[0015] In some embodiments, the inability of the terminal to perform an SDT procedure in the serving cell includes: the terminal is unable to continue a previous SDT procedure in the serving cell. In some embodiments, the inability of the terminal to perform an SDT procedure in the serving cell includes: the terminal is unable to start a new SDT procedure in the serving cell.

[0016] In a possible implementation, the method further includes: stopping the first timer if an RRC reject message is received when the first timer is running, and setting a first variable to a first value if the second timer is not running, where the first value of the first variable indicates that there is a pending RNA update procedure.

[0017] In the present application, when the first timer is running (in other words, when the SDT procedure is being performed), if the second timer expires, the terminal does not execute RNAU and does not set the first variable to the first value, so as to avoid an impact on the currently executed SDT procedure. When the SDT procedure is abnormally terminated (e.g., when the first timer is stopped or expired) and the second timer is not running, the terminal may set the first variable to the first value, so that the terminal can subsequently execute RNAU normally.

[0018] In a possible implementation, the method further includes: stopping the first timer if an RRC reject message is received when the first timer is running, and performing a radio resource control RRC connection resumption procedure for RNAU if the second timer is not running.

[0019] In the present application, when the first timer is running (in other words, when the SDT procedure is being performed), if the second timer expires, the terminal will not execute RNAU to avoid any impact on the currently executed SDT procedure. If the SDT procedure is abnormally terminated (e.g., when the first timer is stopped or expired) and the second timer is not running, the terminal executes RNAU to ensure the normal execution of RNAU.

[0020] In a possible implementation, the method further includes: stopping the first timer if an RRC reject message is received when the first timer is running, starting a third timer if the second timer is not running, and performing an RRC connection resumption procedure for RNAU when the third timer expires and the first timer is not running.

[0021] In a possible implementation, the duration of the third timer is the same as the duration of the second timer.

[0022] In a possible implementation, the duration of the third timer is different from the duration of the second timer.

[0023] In a possible implementation, the non-radio resource control RRC connected state is an RRC inactive state, and after the terminal receives an RRC rejection message, the terminal enters the RRC inactive state.

[0024] In the present application, when the first timer is running (in other words, when the SDT procedure is being performed), if the second timer expires, the terminal will not perform RNAU and will not start the third timer to avoid an effect on the currently performed SDT procedure. If the SDT procedure is abnormally terminated (for example, when the first timer is stopped or expired) and the second timer is not running, the terminal may start the third timer. If the third timer expires and the first timer is not running, the terminal performs a radio resource control (RRC) connection resumption procedure for RNAU to ensure normal execution of RNAU.

[0025] In a possible implementation, the method further includes: when the first timer expires and if the second timer has not run, setting a first variable to a first value, where the first variable being at the first value indicates that there is a pending RNA update procedure.

[0026] In a possible implementation, the method further includes: when the first timer expires, if the second timer is not running, performing a radio resource control (RRC) connection resumption procedure for the RNAU.

[0027] In a possible implementation, the method further includes: starting a third timer when the first timer expires and the second timer is not running, and performing an RRC connection resumption procedure for RNAU when the third timer expires and the first timer is not running.

[0028] In a possible implementation, the duration of the third timer is the same as the duration of the second timer.

[0029] In a possible implementation, the duration of the third timer is different from the duration of the second timer.

[0030] In a possible implementation, the non-radio resource control RRC connected state is an RRC inactive state, and after the first timer expires, the terminal enters the RRC inactive state.

[0031] In a possible implementation, the method further includes: receiving a SIB1 of a second serving cell if cell reselection occurs when the first timer is running, the second serving cell being a serving cell obtained through cell reselection occurring in the terminal, and setting a first variable to a first value 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, the first value of the first variable indicating that there is a pending RNA update procedure.

[0032] In a possible implementation, the method further includes: stopping the first timer if cell reselection occurs when the first timer is running, receiving SIB1 of a second serving cell, the second serving cell being a serving cell obtained through cell reselection occurring in the terminal, and performing a radio resource control (RRC) connection resumption procedure for RNAU when the SIB1 of the second serving cell is received and the second serving cell belongs to the configured RNA and the second timer is not running.

[0033] In a possible implementation, the method further includes: receiving SIB1 of a second serving cell if cell reselection occurs when the first timer is running, the second serving cell being a serving cell obtained through cell reselection occurring on the terminal; starting a third timer if the second serving cell belongs to the configured RNA and the second timer is not running when SIB1 of the second serving cell is received; and performing an RRC connection resumption procedure for RNAU if the first timer is not running when the third timer expires.

[0034] In a possible implementation, the duration of the third timer is the same as the duration of the second timer.

[0035] In a possible implementation, the duration of the third timer is different from the duration of the second timer.

[0036] In a possible implementation, the non-radio resource control RRC connected state is an RRC inactive state, and after cell reselection occurs on the terminal, the terminal is in the RRC inactive state.

[0037] In a possible implementation, after the step of setting the first variable to the first value, the method further includes: performing an RRC connection resumption procedure for the RNAU if the access barring is relaxed and the non-access NAS layer does not request the RRC layer to perform RRC connection resumption, and if the first variable is the first value.

[0038] In a possible implementation, the non-radio resource control RRC connected state is an RRC inactive state.

[0039] According to a second aspect, an embodiment of the present application provides another transmission control method, applied to a terminal in a non-RRC connected state, the method including: setting a first variable to a first value if a first preset condition is satisfied, the first variable being the first value indicating that there is a pending RNA update procedure, the first preset condition including that a first timer is not running, and the first timer is started when the terminal receives an RRC release message including a duration of the first timer.

[0040] For example, the first timer is T380.

[0041] In a possible implementation, the first preset condition further includes: the terminal receiving an RRC rejection message when the second timer is running; the second timer being started when the terminal initiates an RRC connection resumption procedure for the SDT; and the second timer being stopped when the terminal receives the RRC rejection message.

[0042] In a possible implementation, the first preset condition further includes: a second timer expiring; and the second timer being started when the terminal initiates an RRC connection resumption procedure for SDT.

[0043] In a possible implementation, the non-RRC connected state is an RRC inactive state, and after the second timer expires, the terminal is in the RRC inactive state.

[0044] In a possible implementation, the first preset condition further includes: the terminal receives SIB1 of a first serving cell, and the first serving cell belongs to the configured RNA; and, before the step of setting the first variable to a first value when the first preset condition is satisfied, the method further includes: stopping the second timer if cell reselection occurs when the second timer is running, the second timer being started when the terminal initiates an RRC connection resumption procedure for SDT; and receiving SIB1 of the first serving cell, the first serving cell being a serving cell obtained through cell reselection occurring to the terminal.

[0045] In a possible implementation, after the step of setting the first variable to the first value, the method further includes: performing an RRC connection resumption procedure for the RNAU if the access barring is relaxed and the non-access NAS layer does not request the RRC layer to perform RRC connection resumption, and if the first variable is the first value.

[0046] In a possible implementation, the non-RRC connected state is an RRC inactive state.

[0047] In the present application, if the first timer expires when the second timer is running (in other words, when the SDT procedure is being performed), the terminal does not execute RNAU or set the first variable to the first value, so as to avoid any impact on the currently executed SDT procedure. If the SDT procedure is abnormally terminated (e.g., the second timer is stopped or expired) and the first timer is not running, the terminal may set the first variable to the first value, so that the terminal can subsequently execute RNAU normally.

[0048] According to a third aspect, an embodiment of the present application provides yet another transmission control method applied to a terminal in a non-RRC connected state, the method including: starting a first timer; initiating an RRC connection resumption procedure for SDT; indicating, by a lower layer, first information to an upper layer in an RRC connection resumption procedure for SDT, where the first information indicates that the RRC connection resumption procedure for SDT is successful; and stopping the first timer based on the first information.

[0049] In some embodiments, the terminal starts the first timer upon receiving an RRC release message including a duration of the first timer, for example, the first timer is T380.

[0050] In this application, when the SDT procedure is performed, the terminal may stop the first timer, so as to prevent the RNAU from being triggered when the first timer expires. When the SDT is performed, the network equipment may obtain the RNA where the terminal is located, and not triggering the RNAU not only does not affect the network equipment's acquisition of the terminal's status, but also can avoid the impact on the transmission of small data in the SDT procedure.

[0051] In a possible implementation, the step of initiating an RRC connection resumption procedure for SDT includes: the terminal sending an RRC request message to a network device; and a lower layer of the terminal receiving a first response message sent by the network device in response to the RRC request message; and the step of indicating, by the lower layer, the first information to the upper layer includes: the lower layer indicating, based on the first response message, the first information to the upper layer.

[0052] In a possible implementation, the RRC connection resumption procedure for SDT includes: the terminal sending an RRC request message to a network device in a random access procedure; indicating, by a lower layer, first information to a higher layer, the first information including a media access control (MAC) layer indicating the first information to an RRC layer, where the first information indicates that contention resolution is successful; stopping a first timer based on the first information includes: the RRC layer stopping the first timer after receiving the first information indicated by the MAC layer.

[0053] In a possible implementation, the terminal sending an RRC request message to a network equipment includes: the terminal sending an RRC request message to a network equipment in a random access procedure, where the first response message indicates that the contention resolution is successful.

[0054] For example, the first response message is a contention resolution message.

[0055] In a possible implementation, the RRC connection resumption procedure for SDT includes: the terminal sending an RRC request message to a network device based on a pre-configured uplink resource, and the first information indicating that the RRC request message has been successfully sent.

[0056] In a possible implementation, the step of indicating, by the lower layer, the first information to the upper layer includes: the media access control (MAC) layer indicating the first information to the RRC layer; the step of stopping the first timer based on the first information includes: the RRC layer stopping the first timer after receiving the first information indicated by the MAC layer; alternatively, the step of indicating, by the lower layer, the first information to the upper layer includes: the physical layer indicating the first information to the RRC layer; and the step of stopping the first timer based on the first information includes: the RRC layer stopping the first timer based on the first information indicated by the physical layer; alternatively, before the step of indicating, by the lower layer, the first information to the upper layer, the method further includes: the physical layer indicating second information to the MAC layer, where the second information indicates that the RRC request message has been successfully transmitted; the step of indicating, by the lower layer, the first information to the upper layer includes: That is, the MAC layer receives the second information indicated by the physical layer and indicates the first information to the RRC layer. The step of stopping the first timer based on the first information includes: That is, the RRC layer stops the first timer after receiving the first information indicated by the MAC layer.

[0057] In a possible implementation, the step of the terminal sending an RRC request message to the network equipment includes: the terminal sending an RRC request message to the network equipment based on a pre-configured uplink resource, and the first response message indicating that the RRC request message has been successfully sent.

[0058] In a possible implementation, initiating the RRC connection resumption procedure for the SDT includes: initiating the RRC connection resumption procedure for the SDT; and starting a second timer.

[0059] In a possible implementation, after stopping the first timer, the method further includes: stopping the second timer if an RRC reject message is received when the second timer is running, and setting a first variable to a first value if the first timer is not running, where the first value of the first variable indicates that there is a pending RNA update procedure.

[0060] In the present application, if the first timer is stopped in the SDT procedure, the terminal may set the first variable to a first value when the SDT procedure terminates abnormally (e.g., when the second timer is stopped or expires), so that the RNAU may still be triggered thereafter to ensure normal execution of the RNAU.

[0061] In a possible implementation, after stopping the first timer, the method further includes: stopping the second timer if an RRC reject message is received when the second timer is running, and performing a radio resource control RRC connection resumption procedure for RNAU if the first timer is not running.

[0062] In the present application, if the first timer is stopped in the SDT procedure, the terminal may perform RNAU when the SDT procedure terminates abnormally (e.g., the second timer is stopped or expires) to ensure normal execution of RNAU.

[0063] In a possible implementation, after stopping the first timer, the method further includes: stopping the second timer if an RRC reject message is received when the second timer is running, starting a third timer if the first timer is not running, and performing an RRC connection resumption procedure for RNAU if the second timer is not running when the third timer expires.

[0064] In a possible implementation, the duration of the third timer is the same as the duration of the first timer.

[0065] In a possible implementation, the duration of the third timer is different from the duration of the first timer.

[0066] In a possible implementation, the non-radio resource control RRC connected state is an RRC inactive state, and after the terminal receives an RRC rejection message, the terminal enters the RRC inactive state.

[0067] In the present application, when the first timer is stopped in the SDT procedure, the terminal may start a third timer when the SDT procedure terminates abnormally (e.g., the second timer is stopped or expires), and when the third timer expires and the second timer is not running, perform RNAU to ensure the normal execution of RNAU.

[0068] In a possible implementation, the method further includes: when the second timer expires and the first timer is not running, setting a first variable to a first value, where the first variable being at the first value indicates that there is a pending RNA update procedure.

[0069] In a possible implementation, the method further includes: when the second timer expires, if the first timer is not running, performing a radio resource control RRC connection resumption procedure for the RNAU.

[0070] In a possible implementation, the method further includes: starting a third timer when the second timer expires and the first timer is not running, and performing an RRC connection resumption procedure for RNAU when the third timer expires and the second timer is not running.

[0071] In a possible implementation, the duration of the third timer is the same as the duration of the first timer.

[0072] In a possible implementation, the duration of the third timer is different from the duration of the first timer.

[0073] In a possible implementation, the non-radio resource control RRC connected state is an RRC inactive state, and after the first timer expires, the terminal is in the RRC inactive state.

[0074] In a possible implementation, the method further includes: stopping the second timer if cell reselection occurs when the second timer is running, receiving SIB1 of a first serving cell, the first serving cell being a serving cell obtained by cell reselection occurring in the terminal, and setting a first variable to a first value when 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, where the first value of the first variable indicates that there is a pending RNA update procedure.

[0075] In a possible implementation, the method further includes: stopping the second timer if cell reselection occurs when the second timer is running, receiving SIB1 of a first serving cell, the first serving cell being a serving cell obtained by cell reselection occurring in the terminal, and performing a radio resource control (RRC) connection resumption procedure for RNAU if the first serving cell belongs to the configured RNA and the first timer is not running when SIB1 of the first serving cell is received.

[0076] In a possible implementation, the method further includes: stopping the second timer if cell reselection occurs when the second timer is running; receiving SIB1 of a first serving cell, the first serving cell being a serving cell obtained by cell reselection occurring in the terminal; starting a third timer if the first serving cell belongs to the configured RNA and the first timer is not running when SIB1 of the first serving cell is received; and performing an RRC connection resumption procedure for RNAU if the second timer is not running when the third timer expires.

[0077] In a possible implementation, the duration of the third timer is the same as the duration of the second timer.

[0078] In a possible implementation, the duration of the third timer is different from the duration of the second timer.

[0079] In a possible implementation, the non-radio resource control RRC connected state is an RRC inactive state, and after cell reselection occurs on the terminal, the terminal is in the RRC inactive state.

[0080] In a possible implementation, after the step of setting the first variable to the first value, the method further includes: performing an RRC connection resumption procedure for the RNAU if the access barring is relaxed and the non-access NAS layer does not request the RRC layer to perform RRC connection resumption, and if the first variable is the first value.

[0081] In a possible implementation, the non-RRC connected state is an RRC inactive state.

[0082] According to a fourth aspect, an embodiment of the present application provides a terminal including a transceiver, a processor, and a memory, the memory being configured to store a computer program code, the computer program code including computer instructions, and the processor calling the computer instructions, so that the above-mentioned user device executes the transmission control method provided in any one of the first to third aspects of the embodiment of the present application, and the implementation of the first to third aspects.

[0083] According to a fifth aspect, an embodiment of the present application provides a communication device, which may be a terminal or a chip in a terminal. The communication device includes a processing unit, which is configured to execute a transmission control method provided in any one of the first to third aspects of the embodiment of the present application and implementation of the first to third aspects.

[0084] According to a sixth aspect, an embodiment of the present application provides a computer storage medium, the computer storage medium storing a computer program, the computer program including program instructions, which, when executed by a processor, perform the transmission control method provided in any one of the first to third aspects of the embodiment of the present application, and the implementation of the first to third aspects.

[0085] According to a seventh aspect, an embodiment of the present application provides a computer program product, which, when executed on a communication device, enables the communication device to execute a transmission control method provided in any one of the first to third aspects of the embodiments of the present application, and implementations of the first to third aspects.

[0086] According to an eighth aspect, an embodiment of the present application provides an electronic device. The electronic device includes an apparatus for performing the method according to any embodiment of the present application. The electronic device is, for example, a chip. [Brief description of the drawings]

[0087] Hereinafter, a description will be given of the accompanying drawings used in the embodiments of the present application.

[0088] [Figure 1] FIG. 1 is a schematic diagram illustrating the architecture of a communication system according to an embodiment of the present application. [Diagram 2] FIG. 1 is a schematic diagram showing the architecture of a user plane communication protocol stack in new radio NR. [Diagram 3] FIG. 1 is a schematic diagram showing the architecture of a control plane communication protocol stack in NR. [Figure 4] 1 is a schematic diagram showing switching between radio resource control (RRC) states of a user equipment (UE); [Diagram 5] 4A-4D are several schematic flow charts illustrating small data transmission SDT according to an embodiment of the present application; [Figure 6] 4A-4D are several schematic flow charts illustrating small data transmission SDT according to an embodiment of the present application; [Figure 7] 4A-4D are several schematic flow charts illustrating small data transmission SDT according to an embodiment of the present application; [Figure 8] 4A-4D are several schematic flow charts illustrating small data transmission SDT according to an embodiment of the present application; [Figure 9] 4A-4D are several schematic flow charts illustrating small data transmission SDT according to an embodiment of the present application; [Figure 10] 4A-4D are several schematic flow charts illustrating small data transmission SDT according to an embodiment of the present application; [Figure 11] 1 is a schematic flow chart illustrating a transmission control method according to an embodiment of the present application. [Figure 12] FIG. 2 is a sequence diagram according to an embodiment of the present application. [Figure 13] 4 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. [Figure 14]4 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. [Figure 15] 4 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. [Figure 16] 4 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. [Figure 17] 4 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. [Figure 18] FIG. 2 is another sequence diagram according to an embodiment of the present application; [Figure 19] 4 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0089] The technical solutions according to the embodiments of the present application are clearly described below with reference to the accompanying drawings. It should be noted that the terms used in the implementation of the embodiments of the present application are merely used to describe certain embodiments of the present application, and are not intended to limit the present application.

[0090] First, the relevant devices and communication systems related to this application are described.

[0091] In an embodiment of the present application, the network equipment may be equipment configured to transmit or receive information. In some embodiments, the network equipment is an access network equipment, such as, but not limited to, a base station, a user equipment (UE), a radio access point (AP), a transmit reception point (TRP), a repeater, or another network equipment having the function of a base station. A base station is an equipment located in a radio access network (RAN) to provide wireless communication functions. In different radio access systems, the name of a base station may be different, such as, but not limited to, a base station (BTS) in Global System for Mobile Communications (GSM) or Code Division Multiple Access (CDMA), a NodeB (NB) in Wideband Code Division Multiple Access (WCDMA), an evolved base station (eNodeB) in Long Term Evolution (LTE), a next generation base station (gNodeB, gNB) in the fifth generation mobile communication technology (5G), i.e., a base station in New Radio Access (NR), or another future network system.

[0092] In the embodiments of the present application, the terminal may be a device having a wireless communication function. In some embodiments, the terminal is a UE. In some embodiments, the terminal may also be called a mobile station, an access terminal, or a user agent. For example, the terminal is a terminal in the form of a handheld device, a wearable device, a computing device, a portable device, or an in-vehicle device. For example, the terminal is specifically a device such as a mobile phone, a smartphone, a smart glass, a laptop computer, a personal digital assistant, or a cordless phone. In the following embodiments, an example in which the terminal is a UE is used for description.

[0093] 1 is a schematic diagram illustrating an architecture of a communication system according to an embodiment of the present application, which may be, but is not limited to, GSM, CDMA, Wideband Code Division Multiple Access (WCDMA), Time Division Code Division Multiple Access (TD-CDMA), Universal Mobile Telecommunications System (UMTS), LTE, NR, or another future network system.

[0094] As shown in FIG. 1, the communication system may include a core network 110, a network equipment 120, and a UE 130. The core network 110 may be connected to at least one network equipment 120, which may provide wireless communication services to at least one UE 130, which may be connected to at least one network equipment 120 via an air interface. The core network 110 is an important control node in the communication system and is mainly responsible for signaling processing functions, such as but not limited to implementing functions such as access control, mobility management, and session management. In some embodiments, the network equipment 120 is a base station. In NR, the core network 110 may be referred to as a 5G Core Network (5GCore, 5GC) 110, and the network equipment 120 may be referred to as a gNB 120. In some embodiments, the at least one base station may form a next generation radio access network (NB-RAN) node. The NG-RAN node may include at least one gNB 120 connected to the 5GC 110 via an NG interface, and the at least one gNB 120 in the NG-RAN node may be interconnected and communicate with each other via an Xn-C interface. The UE 130 may be connected to the gNB 120 via a Uu interface.

[0095] The core network 110 may transmit downlink data to the UE 130 via the network equipment 120, or the UE 130 may transmit uplink data to the core network 110 via the connected network equipment 120. It should be noted that the configurations and quantities of the core network 110, the network equipment 120, and the UE 130 shown in Fig. 1 are used merely as examples, which are not limited to the embodiments of the present application.

[0096] For ease of understanding, the embodiments of the present application are mainly described by using an example in which the applied communication system is LTE and / or NR, the network equipment is a base station, and one NG-RAN includes at least one base station.

[0097] For purposes of illustration, an example of an NR communication protocol stack is described below.

[0098] Figure 2 is a schematic diagram showing the architecture of the user plane protocol stack in NR. The user plane protocol stack may 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.

[0099] Figure 3 is a schematic diagram showing the architecture of the control plane protocol stack in NR. The control plane protocol stack may include a PHY layer, a MAC layer, an RLC layer, a PDCP layer, a radio resource control (RRC) layer, and a non-access stratum (NAS).

[0100] Compared with the user plane protocol stack in LTE, the user plane protocol stack in NR has a new SDAP layer added. However, the architecture of other layers is consistent, and the specific description is similar. LTE is relatively developed, so detailed description is omitted.

[0101] As shown in Figures 2 and 3, the lower layer of the PDCP layer includes the RLC layer. The PDCP layer can process the control plane RRC messages. The PDCP layer can compress IP packet headers to reduce the number of bits transmitted over the air interface. The PDCP layer can be responsible for control plane encryption and integrity protection of transmitted data. On the receiving side, the PDCP layer performs corresponding decoding and decompression operations. For each radio bearer, one PDCP entity can be configured. The RLC layer is responsible for segmentation / concatenation, retransmission control, and repeat detection, etc. The RLC layer provides services to the PDCP layer and can configure an RLC entity for each radio bearer. The MAC layer controls logical channel multiplexing, hybrid automatic repeat request retransmission, and uplink and downlink scheduling, etc. The MAC layer provides services to the RLC layer in the form of logical channels. The PHY layer is responsible for managing coding / decoding, modulation / demodulation, multi-antenna mapping, and other types of physical layer functions. The PHY layer provides services to the MAC layer in the form of transport channels.

[0102] As shown in FIG. 2 and FIG. 3, the MAC layer may provide services to higher layers (e.g., the RLC layer, etc.) through logical channels (LCH). Based on the type of information transmitted, the logical channels may be classified into control channels, which are for the transmission of control information in the control plane, and traffic channels, which are for the transmission of user data in the user plane. The control channels may include, but are not limited to, common control channels (CCCH) and dedicated control channels (DCCH). The traffic channels include, but are not limited to, dedicated traffic channels (DTCH). The CCCH may always be present, and a UE that does not have an RRC connection to a RAN node may also use the CCCH to perform information transmission. The DCCH may be for the transmission of dedicated control information between the UE and the RAN node. The DTCH may be for the transmission of user data between the UE and the RAN node. In general, the DCCH and the DTCH do not always exist and can be used for communication between the UE and the base station only after the base station connected to the UE resumes the UE context. The UE context includes, but is not limited to, a terminal identifier, a radio bearer (RB)-related configuration, integrity protection and encryption security-related configuration, and quality of service-related configuration.

[0103] The RB may be a connection format established between the UE and the RAN node and may include the associated configuration of physical channels, transport channels, and logical channels. The RB may be classified into a signaling radio bearer (SRB) for carrying control information in the control plane and a data radio bearer (DRB) for carrying user data in the user plane. The DRB may include a PDCP layer entity (PDCP entity for short), an RLC layer entity (RLC entity for short), and logical channels.

[0104] As shown in Figure 3, the RRC layer may be for transmitting RRC messages between the UE and the base station. The RRC message may be, for example, but not limited to, an RRC Resume Request (RRCResumeRequest) that is in NR and may be used by the UE to request resumption of a suspended RRC connection to perform data transmission to the base station. The RRC layer belongs to the Access Stratum (AS).

[0105] For the RRC layer, there are currently three RRC states in a UE: RRC IDLE state, RRC INACTIVE state, and RRC CONNECTED state. The operations performed by the UE in different RRC states are mostly different. For details about the three states and transition procedures, please refer to the example in Figure 4.

[0106] As shown in FIG. 4, when the UE is in the RRC CONNECTED state, an RRC connection is established between the UE and the base station. In some embodiments, when the UE is in the RRC CONNECTED state, a user plane connection and a control plane connection in the UE may be established between 5GC and NG-RAN. The NG-RAN and the UE may hold the UE context of the AS layer. The NG-RAN may obtain the cell to which the UE belongs, the UE may transmit or receive unicast data, and the network (e.g., NG-RAN, etc.) may control the mobility of the UE. For example, the UE may measure a channel between the UE and the base station and report the measurement result to the base station. The base station may determine whether to switch the cell to which the UE belongs based on the measurement result. In other words, in the RRC CONNECTED state, the UE and the base station can perform data transmission normally, and the base station can manage the UE. In some embodiments, if a UE in the RRC CONNECTED state needs to transmit uplink data to the base station, the UE needs to maintain synchronization to the base station based on a timing advance (TA). If a UE in RRC CONNECTED state does not obtain uplink synchronization, the UE may initiate a random access (RA) to the base station. If the UE's uplink advance timer (TAT) keeps running, the UE maintains uplink synchronization. If the UE's TAT ​​expires, the UE's uplink synchronization fails. If the UE needs to transmit uplink data to the base station again, the UE needs to initiate an RA, and a new TA is obtained through the RA. In some embodiments, when the UE is in RRC CONNECTED state, the base station may assign a configuration grant (CG) resource to the UE. If the UE has a data transmission requirement, the UE may transmit uplink data to the base station by using the CG resource. In some embodiments, the base station may configure the CG resource for the UE through an RRC message, and the configuration information may include a time-frequency location and a periodicity.Compared with the method of dynamic scheduling of transmission resources, this method of data transmission by using CG resources can reduce signaling overhead and transmission delay.

[0107] When there are no uplink resources but there is uplink data to be transmitted to the base station, the UE in RRC CONNECTED state may trigger a Buffer Status Report (BSR) report to request the base station to schedule uplink resources. The BSR may indicate the amount of data currently to be transmitted in the data buffer of the UE. The amount of data may be different at different times. For example, if the UE is a smartphone, a user may send a message to another user through a social application installed on the UE. However, the type and amount of messages transmitted by the user at different times may be different. Sometimes the message transmitted may be only a text message, and sometimes the message transmitted may include multiple videos. Therefore, the size of the BSR transmitted by the UE to the base station at different times may also be different. The resources used by the UE to transmit the BSR to the base station (BSR resources for short) may be dynamically scheduled by the base station to the UE.

[0108] When the UE is in the RRC IDLE state, no RRC connection is established between the UE and the base station. In some embodiments, when the UE is in the RRC IDLE state, the UE may select a public land mobile network (PLMN), the UE may receive system information broadcast by the base station, cell reselection may occur at the UE, the UE may perform 5GC initiated paging for downlink transmissions, the UE may perform discontinuous reception (DRX) configured by the NAS layer for core network paging, etc.

[0109] The RRC INACTIVE state is a newly added RRC state in NR. In some embodiments, for a UE that does not frequently perform data transmission, the base station normally keeps the UE in the RRC INACTIVE state. In some embodiments, when the UE is in the RRC INACTIVE state, the UE may select a PLMN, the UE may receive system information broadcast by the base station, and cell reselection may occur in the UE. The NG-RAN initiates paged paging, and the NG-RAN manages the RAN-based notification area (RNA). For example, the UE triggers an RNA update (RNAU) to inform the base station of the RNA where the UE is currently located, and the NG-RAN configures DRX for RAN paging. The user plane and control plane connections in the UE may be set up during 5GC and NG-RAN. The NG-RAN and the UE may hold the UE context of the AS layer, and the NG-RAN may obtain the RNA where the UE is located. In some embodiments, after the UE and the base station set up the RRC connection, the UE transitions to the RRC CONNECTED state. If the UE in the RRC CONNECTED state does not need to perform data transmission to the base station within a preset time, the base station may instruct the UE to transition to the RRC INACTIVE state. For example, the base station may send an RRC release with suspend instruction (RRCRelease with suspend instruction) message to the UE. After receiving the RRCRelease with suspend instruction message, the UE retains the UE context and transitions to the RRC INACTIVE state.

[0110] The above three states in the RRC layer may be switched between each other. As shown in FIG. 4, in some embodiments, when a UE is in an RRC IDLE state or an RRC INACTIVE state (which may be collectively referred to as a non-RRC connected state), if data transmission needs to be performed, an RRC connection setup procedure or an RRC connection resumption procedure may be performed. For example, a UE in an RRC IDLE state may send an RRC Setup Request message to a base station and then receive an RRC Setup message sent by the base station. After receiving the RRC Setup message, the UE may set up an RRC connection to the base station and transition to an RRC CONNECTED state. For example, a UE in an RRC INACTIVE state may send an RRCResumeRequest message to a base station and then receive an RRC Resume message sent by the base station. After receiving the RRCResume message, the UE may transition to an RRC CONNECTED state. In some other embodiments, when the UE is in a non-RRC connected state, the UE may also perform an RRC connection establishment procedure or an RRC connection resumption procedure in response to the base station's paging message. For example, when there is data to be transmitted to the UE, the core network may instruct the base station to send a paging message to the UE.

[0111] In some embodiments, the UE may transition from the RRC CONNECTED state to the RRC INACTIVE state or the RRC IDLE state based on the instruction of the base station. In some embodiments, if the UE does not need to perform data transmission thereafter, the base station may release the UE, which causes the UE to transition to the RRC INACTIVE state or the RRC IDLE state. Examples are as follows:

[0112] Example 1: The UE transitions from the RRC CONNECTED state to the RRC INACTIVE state based on the instruction of the base station. Specifically, the base station may send a release message with suspend indication, such as an RRCRelease message with suspend indication, to the UE, which causes the UE to transition to the RRC INACTIVE state. In this case, the RRC connection between the UE and the base station is interrupted, but at least one RAN node reserves the UE context of the UE.

[0113] Example 2: The UE transitions from the RRC CONNECTED state to the RRC IDLE state based on the instruction of the base station. Specifically, the base station may send a release message, such as an RRC Release (RRCRelease) message, to the UE, which causes the UE to transition to the RRC IDLE state. In this case, the RRC connection between the UE and the base station is stopped, and the RAN node deletes the UE context of the UE.

[0114] In some embodiments, the UE may selectively transition from the RRC INACTIVE state to the RRC IDLE state based on the instruction of the base station. For example, after the UE in the RRC INACTIVE state sends an RRC connection resumption request, the base station releases the UE, which causes the UE to transition to the RRC IDLE state. It may be understood that the speed at which the UE transitions from the RRC INACTIVE state to the RRC CONNECTED state is faster than the speed at which the UE transitions from the RRC IDLE state to the RRC CONNECTED state.

[0115] In some embodiments, when a UE in RRC IDLE or RRC INACTIVE state needs to perform data transmission, the UE may perform an RRC connection setup procedure or an RRC connection resumption procedure to request to transition to an RRC CONNECTED state to perform data transmission. When a UE in RRC IDLE or RRC INACTIVE state does not have resources to transmit an RRCSetupRequest message or an RRCResumeRequest message, the UE needs to initiate a Random Access (RA) procedure. The following describes RA by using an example.

[0116] In some embodiments, the UE may obtain the RA configuration of the current cell from system information broadcast by the base station. For example, the configuration includes available random access preambles (RAndoMACCEss preambles) and RA resources for transmitting the random access preambles. For example, the RA resources for transmitting the random access preambles are time-frequency resources used by the UE to transmit the random access preambles, and may also be referred to as random access channel opportunities (ROs). In some embodiments, the RA may include 4-step random access (abbreviated as 4-step RA) and 2-step random access (abbreviated as 2-step RA). The base station may broadcast the RA configuration corresponding to the 4-step RA and the RA configuration corresponding to the 2-step RA in the system message, or may broadcast only the RA configuration corresponding to the 4-step RA in the system message, or may broadcast only the RA configuration corresponding to the 2-step RA in the system message.

[0117] In some embodiments, the base station may broadcast an RA configuration corresponding to 4-step RA and an RA configuration corresponding to 2-step RA in a system message. If the UE is not configured with contention-free random access (CFRA) resources, the UE may decide to initiate a 4-step RA or a 2-step RA based on the relative value of a currently measured reference signal received 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 may initiate a 2-step RA. If the currently measured RSRP is less than the preset RSRP threshold, the UE may initiate a 4-step RA.

[0118] In step 3 of 4-step RA, the message sent by the UE to the base station may be referred to as message 3 (msg3 for short). In step 1 of 2-step RA, the message sent by the UE to the base station may be referred to as message A (msgA for short). In some embodiments, "msg3" or "msgA" may include an RRC message. The RRC message may be different when the UE is in different RRC states and in different service scenarios. For example, when a UE in an RRC INACTIVE state has data to transmit to the base station, the msg3 sent by the UE to the base station may include an RRCResumeRequest message to resume the interrupted RRC connection, transition to an RRC CONNECTED state, and request the base station to perform data transmission.

[0119] In general, when a UE in a non-RRC connected state has uplink data to be transmitted to a base station or receives a paging message transmitted by the base station, where the paging message is used by the base station to indicate that there is downlink data to be transmitted to the UE, the UE needs to set up an RRC connection again or resume the RRC connection to transition to an RRC CONNECTED state, and then perform data transmission to the base station in the RRC CONNECTED state. However, the above-mentioned method is relatively applicable when the amount of data to be transmitted between the UE and the base station is large. When the data packet being transmitted is small, this kind of data packet may be called small data, and the signaling required for the UE state switching procedure is even larger than small data, causing unnecessary power consumption and signaling overhead of the UE. Therefore, when the UE is in a non-RRC connected state, it is necessary to perform transmission of small data to the base station. For example, when a UE in an RRC INACTIVE state has a request to transmit uplink small data, the UE may transmit uplink small data to the base station.

[0120] In the embodiment of the present application, the small data may include, but is not limited to, a data packet whose data amount is less than a preset threshold (such as a transport block size instructed by a base station), a data packet whose data label is small data, and a data packet whose data type belongs to small data. Data packets other than small data may be referred to as large capacity data, and include, but are not limited to, a data packet whose data amount is equal to or greater than a preset threshold, a data packet whose data label is large capacity data, and a data packet whose data type belongs to large capacity data. The data label and / or data type may be jointly negotiated by the UE and the network device. For example, the data label may include large capacity data and small data. For example, data whose data type is a heartbeat packet is small data, and data whose data type is a file, video, or audio is large capacity data. For example, the small data may be an instant messaging message of an application (APP) of the UE, a heartbeat packet of the APP, or a push message of the APP, etc., the small data may be periodic data of a wearable device, etc., and the small data may be service data of an Internet of Things (IoT) device, etc.

[0121] In some embodiments, the UE in a non-RRC connected state performing small data transmission to the base station may include the following: instead of performing small data transmission after the UE transitions to an RRC CONNECTED state, the UE performs small data transmission in an RA procedure. The above-mentioned transmission procedure may be referred to as RA-based small data transmission (SDT) (abbreviated as RA-SDT). In some embodiments, the RA may include 4-step RA and 2-step RA, and the SDT may also include SDT based on 4-step RA (abbreviated as 4-step SDT) and SDT based on 2-step RA (abbreviated as 2-step SDT). For an example of the procedure of the 4-step SDT, see FIG. 5 and FIG. 6, and for an example of the procedure of the 2-step SDT, see FIG. 7 and FIG. 8. The implementation of the RA-SDT is similar to the implementation of the RA. For example, the UE may obtain the configuration of RA-SDT from system information broadcasted by the base station, and the UE may decide to initiate 4-step SDT or 2-step SDT based on the relative values ​​of the currently measured RSRP and the preset RSRP threshold.

[0122] In some other embodiments, the UE in a non-RRC connected state performing transmission of small data to the base station may further include: the UE performs transmission of small data via pre-assigned CG resources or pre-configured uplink resources (PUR) instead of first transitioning to an RRC CONNECTED state and then performing transmission of small data. The above-mentioned transmission procedure may be referred to as CG-based SDT (CG-SDT for short). For specific procedure examples, please refer to Figures 9 and 10.

[0123] In some embodiments, the SDT has multiple different application scenarios, and different implementations of the SDT, such as RA-SDT or CG-SDT, may be used based on the application scenario. Specific examples are as follows:

[0124] Example 1: In CG-SDT, resources (e.g., CG resources or PUR, etc.) indicated by the CG-SDT configuration are delivered to the UE by the base station through dedicated control signaling. Therefore, the CG-SDT configuration is applied to the UE in the cell covered by the base station, and the CG-SDT configuration provided to one cell cannot be reused by the UE in the other cell. If the UE moves to the coverage of another network device, the resources indicated by the CG-SDT configuration cannot be used. Such a function can be applied, for example, to the following scenario. That is, for IoT applications, the mobility of the UE is limited, and generally, all connections are set to the same cell to transmit data, and the cell is rarely changed, so that the UE in the IoT field may preferentially use the CG-SDT.

[0125] Example 2: The RA configuration related to the configuration of RA-SDT may be provided by the system information transmitted by the base station. Each time the UE performs selection to a new cell, the UE may read and apply the configuration broadcast by the system information. Such a function may be applied, for example, to the following scenario: For applications such as instant messaging messages on a smartphone, the mobility of the UE is relatively high, and the UE may move from the coverage of one base station to the coverage of another base station. If the UE moves from the coverage of base station A to the coverage of base station B, and performs SDT in the coverage of base station B by using resources indicated by the configuration belonging to the CG-SDT transmitted by base station A before the movement, data transmission cannot be performed. In the RA-SDT, resources for transmitting random access preambles are broadcast by the base station in real time, so that a UE with high mobility may preferentially use the RA-SDT.

[0126] Indeed, whether the UE uses CG-SDT or RA-SDT may not be restricted by the scenario, and the scheme used to perform SDT may be determined based on the implementation of the UE.

[0127] For example, the resource for executing CG-SDT is specially configured by the base station for the UE, so the success rate of the execution of CG-SDT by the UE is high. The random access resource of RA-SDT is broadcast by the network equipment, and all UEs that can receive the broadcast message can start RA-SDT on the random access resource. Multiple UEs compete for resources, which may cause contention failure. Therefore, the success rate of RA-SDT is not higher than that of CG-SDT, and CG-SDT can be more effective than RA-SDT. In general, the UE preferentially selects CG-SDT, and the UE also needs to meet the condition for selecting CG-SDT. If this condition is not met, the UE may select RA-SDT. For example, it is determined whether the resource indicated by the configuration of CG-SDT exists in the coverage of the normal uplink (NUL) carrier or the supplemental uplink (SUL) carrier where the UE is currently located. If the resources indicated by the configuration of CG-SDT exist and there are valid resources in the resources indicated by the configuration of CG-SDT, the UE may select CG-SDT; otherwise, the UE selects RA-SDT.

[0128] It may be understood that the base station may first configure a DRB used to carry data for the UE, and the UE may perform data transmission only after resuming the context (including the DRB). In some embodiments, the DRBs configured by the base station for the UE may include a DRB used to transmit small data (SDT DRB for short) and a DRB used to transmit large data (non-SDT DRB for short). The UE can start the SDT only when small data carried by the SDT DRB arrives. If large data carried by the non-SDT DRB arrives, the UE cannot start the SDT. When the UE starts the SDT, the UE context needs to be resumed, and the UE context may include the SDT DRB.

[0129] In some embodiments, the status of the SDT may be determined based on the status of a first timer, which may be expressed as T3XX, where X is a non-negative integer less than 10. The first timer may be referred to as an SDT failure detection timer, and the first timer may be a timer in the RRC layer.

[0130] In some embodiments, when the UE initiates an RRC connection resumption procedure for the SDT, the UE may start a first timer. In some embodiments, when the UE initiates an RRC connection resumption procedure for the SDT, the UE may initialize an RRC connection resumption procedure for the SDT and start a first timer. In some other embodiments, if the UE initiates an RRC connection resumption procedure for the SDT, the UE may start a first timer when the UE transmits an RRC request message to the base station to initiate an RRC connection resumption procedure for the SDT. In some embodiments, the condition for starting the first timer includes: initializing an RRC connection resumption procedure for the SDT. In some other embodiments, the condition for starting the first timer includes: transmitting an RRC request message to initiate an RRC connection resumption procedure for the SDT. For example, the RRC request message is an RRC request message in msg3 or msgA transmitted by the UE to the base station based on the RA-SDT. As another example, the RRC request message is an RRC request message transmitted by the UE to the base station based on the CG-SDT.

[0131] In some embodiments, the UE may stop the first timer when the UE receives an RRC response message or when cell reselection is performed by the UE. In some embodiments, the condition for stopping the first timer may include receiving an RRC response message or cell reselection occurring. The RRC response message may be, for example, an RRCResume message, an RRCSetup message, an RRCRelease message, an RRCRelease message with suspend indication, an RRCReject message, or another RRC message having the same functionality but not standardized in Third Generation Partnership Project (3GP). When the UE receives an RRCRelease message, an RRCRelease message with suspend indication, or another RRC message having the same functionality but not standardized in 3GP, the UE may consider the SDT to be successful and may stop the first timer. When the UE receives an RRCResume message, an RRCSetup message, or another RRC message having the same functionality but not standardized in 3GP, the UE may consider the SDT to be successful and stop the first timer, or the UE may consider the SDT to be successful, continue performing data transmission and stop the first timer after the UE transitions to an RRC CONNECTED state. When the UE receives an RRCReject message, or another RRC message having the same functionality but not standardized in 3GP, the UE may consider the SDT to be unsuccessful and stop the first timer.

[0132] In some embodiments, if the UE does not receive any response message sent by the base station, such as a contention resolution message, an RRC response message, or another response message, during the period from when the first timer is started to when the first timer expires, the UE may consider the SDT to have failed and automatically terminate the SDT. It may be understood that the first timer may be used to avoid a case where the base station does not respond to the UE for a long time after the UE transmits a request message or data to the base station.

[0133] An example of an SDT transmission procedure will be described below.

[0134] 5 is an example schematic flow chart showing a 4-step SDT procedure in the user plane. The procedure shown in FIG. 5 may include, but is not limited to, the following steps:

[0135] S111: The UE sends a random access preamble to the base station.

[0136] In some embodiments, the base station may send a broadcast message to the UE, the broadcast message including first resource configuration information, the first resource configuration information indicating a random access resource for transmitting a random access preamble. Optionally, the first resource configuration information may specifically indicate a first random access resource for initiating a normal random access. Optionally, the first resource configuration information may specifically indicate a second random access resource for transmitting a random access preamble in a RA-SDT procedure. The random access preamble may be generated by the UE according to a specific rule, but the base station may identify the random access preamble generated by the UE.

[0137] In some embodiments, the random access preamble transmitted by the UE to perform the RA-SDT may be different from the random access preamble transmitted by the UE to initiate a normal RA without performing the RA-SDT. In other words, the base station may identify the UE's intent by using different random access preambles. For example, the UE's intent is to perform the RA-SDT or to initiate an RA.

[0138] In some other embodiments, the random access preamble sent by the UE to perform the RA-SDT may alternatively be the same as the random access preamble sent by the UE to initiate a normal RA without performing the RA-SDT.

[0139] In some embodiments, when 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 in the RA-SDT procedure, the UE may transmit a random access preamble on different random access resources based on different intentions. In this manner, the base station may identify the UE's intention by using different resources for receiving the random access preamble. For example, if the UE intends to initiate RA, the UE transmits a random access preamble on the first random access resource. Upon receiving the random access preamble via the first random access resource, the base station may determine that the UE's intention is to initiate RA. If the UE intends to perform RA-SDT, the UE transmits a random access preamble on the second random access resource. Upon receiving the random access preamble via the second random access resource, the base station may determine that the UE's intention is to perform RA-SDT.

[0140] In some other embodiments, the random access resources of the random access preamble sent by the UE to perform the RA-SDT may alternatively be the same as the random access resources used by the UE to initiate a normal RA without performing the RA-SDT.

[0141] S112: The base station sends a random access response (RAR) to the UE in response to the random access preamble.

[0142] Specifically, after sending the random access preamble to the base station, the UE may monitor the physical downlink control channel (PDCCH) in 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 in the RAR time window, the UE may determine that the current RA has failed. The RAR is for scheduling an uplink grant (UL grant) for the UE so that the UE may send msg3 (including the RRC request message in S113) on the resource scheduled by the RAR.

[0143] In some embodiments, the RAR may further include at least one of a Temporary Cell-Radio Network Temporary Identifier (TC-RNTI) and a Timing Advance (TA), which is used by the UE to perceive uplink synchronization.

[0144] S113: The UE sends uplink small data and an RRC request message to the base station on the resources allocated via the RAR.

[0145] In some embodiments, the RRC request message may carry intent information. The intent information indicates the UE's intent to send the RRC request message. For example, the UE's intent is to perform RA-SDT or to start an RA. For example, if the random access preamble sent by the UE to start the RA-SDT is the same as the random access preamble used by the UE to start a normal RA without performing RA-SDT, or the random access resource for sending the random access preamble and used by the UE to start the RA-SDT is the same as the random access resource for sending the random access preamble and used by the UE to start a normal RA without performing RA-SDT, the RRC request message sent by the UE to perform the RA-SDT may carry intent information, which indicates the UE's intent to start the RA-SDT instead of starting a normal RA.

[0146] In some other embodiments, the UE may transmit a BSR when it transmits msg3 to the base station, and the base station may obtain the UE's intention through the BSR transmitted by the UE. For example, the UE's intention is to perform RA-SDT or to start RA. For example, the random access preamble transmitted by the UE to perform RA-SDT is the same as the random access preamble transmitted by the UE to start a normal RA without performing RA-SDT, or for transmitting the random access preamble, the random access resource used by the UE to perform RA-SDT is the same as the random access resource used by the UE to start a normal RA without performing RA-SDT. If the UE needs to perform RA-SDT, the UE may transmit a BSR when it transmits msg3 to the base station, and the BSR indicates the amount of data of small data, and the base station may confirm through the received BSR that the UE's intention is to start RA-SDT, not to start a normal RA.

[0147] In some embodiments, the RRC request message in msg3 may be different when the UE is in different RRC states and different service scenarios. For example, in the RRC IDLE state, the RRC request message sent by the UE (optionally, in this case, the UE may store UE context, such as configuration information, which may include a key for encrypting uplink small data, or the terminal may not store terminal context) may include an RRCConnectionRequest message, an RRCConnectionResumeRequest message, an RRCEarlyDataRequest message, an RRCResumeRequest message, an RRCResumeRequest1 message, an RRCSetupRequest message, or another RRC message having the same functionality but not standardized by 3GPP. The RRC request message sent by a UE in RRC INACTIVE state may be an RRCConnectionRequest message, an RRCConnectionResumeRequest message, an RRCEarlyDataRequest message, an RRCResumeRequest message, an RRCResumeRequest1 message, an RRCSetupRequest message, or another RRC message having the same functionality but not standardized by 3GPP.

[0148] In some embodiments, the UE may send uplink small data and an RRC request message to the base station to initiate an RRC connection resumption procedure for the 4-step SDT. In some embodiments, the RRC request message to initiate an RRC connection resumption procedure for the 4-step SDT may include a resumeCause information element (IE), and the ResumeCause IE may be set to mo-data.

[0149] In some embodiments, the UE first initializes an RRC connection resumption procedure for the SDT and then transmits an RRC request message to the base station based on the 4-step SDT. In some embodiments, the UE starts a first timer when it initializes the RRC connection resumption procedure for the SDT. In some other embodiments, the UE starts a first timer when it transmits uplink small data and an RRC request message to the base station based on the 4-step SDT.

[0150] In some embodiments, msg3 may include an identifier of the UE, such as a unique identifier of the UE in the core network. In some embodiments, msg3 may include related information of a base station previously connected to the UE, such as an Inactive Radio Network Temporary Identifier (I-RNTI). In some embodiments, msg3 may include information used for ciphering and integrity protection.

[0151] In some embodiments, uplink small data transmission may be performed on a DTCH and RRC message transmission may be performed on a CCCH. The small data and RRC request messages may be encapsulated at the MAC layer and transmitted to the base station over the PHY layer.

[0152] S114: After receiving the RRC request message, the base station sends a contention resolution message to the UE.

[0153] In some embodiments, after receiving the uplink small data and the RRC request message, the base station may resume the UE context and send the received uplink small data to the core network.

[0154] In some embodiments, the contention resolution message is actually a contention resolution identity media access control element (contention resolution identity MAC CE), and the contention resolution identity MAC CE may indicate to the UE that the contention resolution is successful. In some embodiments, the UE may determine whether the msg3 sent by the contention resolution identity MAC CE matches the msg3 sent in S113, and if the msg3 matches, determine that the contention resolution corresponding to the current RA-SDT procedure is successful or determine that the current RA-SDT procedure is successful.

[0155] S115: The base station sends an RRC response message to the UE.

[0156] In some embodiments, if the core network has downlink small data to transmit to the UE, the core network may transmit the downlink small data to the base station. The base station may then transmit the downlink small data to the UE along with an RRC response message. The transmission of the downlink small data may be performed on a DTCH, and the downlink small data is multiplexed at the MAC layer with the RRC response message, whose transmission is performed on a DCCH.

[0157] In some embodiments, the UE may determine whether the uplink small data transmission is successful based on the RRC response message.

[0158] Example 1: The RRC response message sent by the base station is an RRCConnectionRelease message, an RRCConnectionResume message, an RRCConnectionSetup message, an RRCRelease message, an RRCResume message, an RRCSetup message, or another RRC message having the same function but not standardized by 3GPP. Upon receiving the RRC response message, the UE may determine that the SDT transmission is successful this time and stop the first timer.

[0159] Example 2: The RRC response message sent by the base station is an RRCConnectionReject message, an RRCReject message, or another RRC message having the same function but not standardized by 3GPP. Upon receiving the RRC response message, the UE may determine that the SDT transmission has failed this time and stop the first timer.

[0160] In some embodiments, the UE may maintain the current RRC state or transition to another RRC state based on the RRC response message.

[0161] Example 1: When the core network has no further data transmission request, the RRC response message sent by the base station is an RRC Early Data Complete message, an RRC Connection Release message, an RRCRelease message with suspend configuration, an RRCRelease message, or another RRC message with the same function but not standardized in 3GPP. Upon receiving the RRC response message, the UE may consider the SDT transmission procedure successful this time and stop the first timer. Furthermore, the UE may maintain the current non-RRC connected state in response to the RRC response message. Optionally, the RRC response message (e.g., an RRCRelease message, etc.) may include a next hop sequence number (NCC) for encrypting small data by the UE when the UE starts the SDT next time.

[0162] Example 2: When the core network has a requirement for further data transmission, the core network may trigger a connection setup indication procedure, and the RRC response message sent by the base station is an RRCConnectionSetup message, an RRCConnectionResume message, an RRCSetup message, an RRCResume message, or another RRC message having the same function but not standardized in 3GPP. Upon receiving the RRC response message, the UE may consider that the SDT transmission procedure is successful this time and stop the first timer. Furthermore, the UE may transition to an RRC CONNECTED state in response to the RRC response message.

[0163] In some embodiments, if the UE does not receive an RRC response message in S115, the UE considers the transmission of the small data in S113 to be unsuccessful. For example, if the UE still does not receive an RRC response message when the first timer expires, the UE considers the transmission of the small data in S113 to be unsuccessful. If the UE receives an RRC response message in S115, the UE considers the transmission of the small data in S113 to be successful. That is, the UE may determine whether the transmission of the small data in S113 is successful or not depending on whether the RRC response message is received.

[0164] It should be noted that whether or not the core network has a requirement for further data transmission does not include a requirement for the transmission of downlink small data by the base station in S115.

[0165] 6 is an example schematic flow chart showing a 4-step SDT procedure in the control plane. The procedure shown in FIG. 6 may include, but is not limited to, the following steps:

[0166] S121: The UE sends a random access preamble to the base station.

[0167] S122: The base station sends a RAR to the UE in response to the random access preamble.

[0168] Specifically, S121 and S122 are similar to S111 and S112 in FIG. 5, and the details will not be described again.

[0169] S123: The UE sends an RRC request message carrying uplink small data to the base station on the resources allocated via the RAR.

[0170] Specifically, S123 is similar to S113 in Figure 5, with the difference being that the uplink small data is not encapsulated in msg3 at the MAC layer and then transmitted, but is instead carried in msg3 and transmitted. In some embodiments, the uplink small data may be carried in msg3, and the transmission of the uplink small data is performed on the CCCH. For example, the uplink small data may be carried in a NAS layer related IE (e.g., a dedicated information NAS (dedicatedInfoNAS) IE) included in the RRCEarlyDataRequest message, and the transmission of the uplink small data is performed on the CCCH.

[0171] S124: After receiving the RRC request message, the base station sends a contention resolution message to the UE.

[0172] Specifically, S124 is similar to S114 in FIG. 5, with the difference being that the RRC request message received by the base station includes uplink small data. In some embodiments, the base station may transmit the uplink small data to the core network through msg3 carrying the uplink small data. For example, the base station may transmit the uplink small data to the core network by forwarding the NAS-related IE included in msg3.

[0173] S125: The base station sends an RRC response message to the UE.

[0174] Specifically, S125 is similar to S115 in FIG. 5, and the details will not be described again.

[0175] 5 and 6 are described by using an example in which S111 and / or S121 are executed when the UE transmits uplink small data to the base station, in other words, when the UE actively initiates the small data transmission procedure. However, in a specific implementation, there is also a case in which the UE passively initiates the small data transmission procedure based on the instruction of the base station, for example, Mobile Terminated (MT) EDT in LTE (abbreviated as MT-EDT). The transmission procedure in this case is similar to the transmission procedure shown in FIG. 5 and FIG. 6, and the differences are specifically described as follows:

[0176] Before S111, if the core network has downlink small data to be transmitted to the UE, the core network may transmit a paging message to the base station. In some embodiments, the paging message may carry data amount information of the downlink small data. In some embodiments, the base station may transmit the paging message to the UE, and the UE decides to start the 4-step SDT based on the relative value of the currently measured RSRP and the preset RSRP threshold. For example, the base station may trigger the MT-EDT based on the paging message and transmit a paging message carrying an MT-EDT indication, which causes the UE to trigger the MO-EDT for the MT-EDT. Unlike the above-mentioned case where the UE actively initiates the small data transmission procedure, in S113, the UE may transmit only an RRC message to the base station, and may not transmit uplink small data. Optionally, the RRC message may further carry cause information for triggering the MT-EDT. In response, the base station may receive the downlink small data sent by the core network, and at S115, the base station may send an RRC response message and the downlink small data to the UE.

[0177] Similarly, before S121, if the core network has downlink small data to be transmitted to the UE, the core network may transmit a paging message to the base station. In some embodiments, the paging message may carry data amount information of the downlink small data. In some embodiments, the base station may transmit a paging message to the UE, and the UE decides to start the 4-step SDT based on the relative value of the currently measured RSRP and the preset RSRP threshold. Unlike the above-mentioned case where the UE proactively initiates the small data transmission procedure, the RRC message transmitted by the UE to the base station in S123 may not carry uplink small data, and may optionally further carry cause information for triggering the MT-EDT. Correspondingly, the base station may receive the downlink small data transmitted by the core network. The RRC response message transmitted by the base station to the UE in S125 may carry the downlink small data.

[0178] 7 is an example schematic flow chart showing a 2-step SDT procedure in the user plane. The procedure shown in FIG. 7 may include, but is not limited to, the following steps:

[0179] S211: The UE sends a random access preamble, an RRC request message, and uplink small data to the base station.

[0180] In some embodiments, the transmission resource for performing S211 by the UE may be obtained based on information broadcast by the base station. For example, the UE may transmit a random access preamble by using an RA resource broadcast by the base station, and the UE may transmit an RRC request message by using a PUSH resource broadcast by the base station.

[0181] In some embodiments, the base station may identify the UE's intention by using different random access preambles. In some other embodiments, the base station may identify the UE's intention by using different resources to receive the random access preamble. In some other embodiments, the base station may obtain the UE's intention based on the BSR transmitted by the UE. In some other embodiments, the RRC request message may carry intention information, where the intention information indicates the UE's intention to transmit the RRC request message, for example, the UE's intention is to perform RA-SDT or start RA. For details, please refer to the examples of S111 and S113 in FIG. 5. Details will not be described again.

[0182] In some embodiments, when the UE is in different RRC states and different service scenarios, the RRC request message in msgA may be different. For details, see the example of the RRC request message in msg3 in Figure 5. The details will not be described again.

[0183] In some embodiments, the RRC request message and the uplink small data may be carried in a Physical Uplink Shared Channel (PUSCH) transmission. The transmission of the uplink small data may be performed on a DTCH and the transmission of the RRC message may be performed on a CCCH. The small data and the RRC request message may be encapsulated at the MAC layer and transmitted to the base station via the PHY layer.

[0184] In some embodiments, the UE may send uplink small data and an RRC request message to the base station to initiate an RRC connection resumption procedure for the 2-step SDT. In some embodiments, in the RRC request message to initiate an RRC connection resumption procedure for the 2-step SDT, the resumeCause IE may be set to mo-data.

[0185] In some embodiments, the UE first initializes an RRC connection resumption procedure for the SDT and then sends an RRC request message to the base station based on the 2-step SDT. In some embodiments, the UE starts a first timer when it initializes the RRC connection resumption procedure for the SDT. In some other embodiments, the UE starts the first timer when it sends uplink small data and an RRC request message to the base station based on the 2-step SDT.

[0186] For an explanation of the RRC request message and the uplink small data, please refer to the explanation of the RRC request message and the uplink small data in S113 in Figure 5. The details will not be described again.

[0187] S212: After receiving the RRC request message, the base station sends a message B to the UE.

[0188] In some embodiments, after receiving the uplink small data and the RRC request message, the base station may resume the UE context and send the received uplink small data to the core network.

[0189] In some embodiments, a message sent by the base station to the UE in step 2 of the 2-step RA may be referred to as message B (or msgB for short). For example, msgB may include a successRAR or a fallbackRAR.

[0190] In some embodiments, msgB includes successRAR, where successRAR includes the content included in the contention resolution field, e.g., the contention resolution MAC CE. Upon receiving the successRAR, 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. Optionally, the contention resolution field in the successRAR may indicate to the UE that the contention resolution is successful. Optionally, the UE may determine whether the contention resolution field in the successRAR matches the msgA sent in S211. If the contention resolution field in the successRAR matches the msgA sent in S211, 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. In some other embodiments, msgB includes fallbackRAR. After receiving the fallbackRAR, the UE transmits msg3 and uplink small data to the base station again.

[0191] S213: The base station sends an RRC response message to the UE.

[0192] In some embodiments, if the core network has downlink small data to send to the UE, the core network may send the downlink small data to the base station, which may then send the downlink small data to the UE along with an RRC response message.

[0193] For an explanation of the RRC response message, please refer to the explanation of the RRC response message in S115 in Figure 5. Details will not be explained again.

[0194] 8 is an example schematic flow chart illustrating a 2-step SDT procedure in the control plane. The procedure illustrated in FIG. 8 may include, but is not limited to, the following steps:

[0195] S221: The UE sends a random access preamble and an RRC request message carrying uplink small data to the base station.

[0196] Specifically, S221 is similar to S211 in Figure 7, with the difference being that the uplink small data is not transmitted together with the RRC request message in msgA, but is instead carried in the RRC request message in msgA. In some embodiments, the RRC request message carrying the uplink small data may be carried in a Physical Uplink Shared Channel (PUSCH) transmission, and the transmission of the RRC request message may be performed on a CCCH.

[0197] S222: After receiving the RRC request message, the base station sends msgB to the UE.

[0198] Specifically, S222 is similar to S212 in FIG. 7, with the difference being that the RRC request message received by the base station includes uplink small data. In some embodiments, the base station may transmit the uplink small data to the core network through the RRC request message carrying the uplink small data. For example, the base station may transmit the uplink small data to the core network by forwarding an RRCResumeRequest message carrying the uplink small data.

[0199] S223: The base station sends an RRC response message to the UE.

[0200] Specifically, S223 is similar to S213 in FIG. 7, and the details will not be described again.

[0201] 7 and 8 are described by using an example in which S211 and / or S221 are executed when the UE transmits uplink small data to the base station, in other words, when the UE actively initiates the small data transmission procedure. However, in a specific implementation, there is also a case in which the UE passively initiates the small data transmission procedure based on the instruction of the base station. The transmission procedure in this case is similar to the transmission procedure shown in FIG. 7 and FIG. 8, and the differences are specifically described as follows.

[0202] Before S211, if the core network has downlink small data to be transmitted to the UE, the core network may transmit a paging message to the base station. In some embodiments, the paging message may carry data amount information of the downlink small data. In some embodiments, the base station may transmit the paging message to the UE, and the UE may determine to start the 2-step SDT based on the relative value of the currently measured RSRP and the preset RSRP threshold. For example, the base station may trigger the MT-EDT based on the paging message and transmit a paging message carrying an MT-EDT indication to the UE, whereby the UE triggers the MO-EDT for the MT-EDT. Unlike the above-mentioned case where the UE proactively initiates the small data transmission procedure, in S211, the UE may transmit only a random access preamble and an RRC request message to the base station, and may not transmit uplink small data. Optionally, the RRC request message may further carry cause information for triggering the MT-EDT. In response, the base station may receive downlink small data sent by the core network, and at S213, the base station may send an RRC response message and the downlink small data to the UE.

[0203] Similarly, before S221, if the core network has downlink small data to be transmitted to the UE, the core network may transmit a paging message to the base station. In some embodiments, the paging message may carry data amount information of the downlink small data. In some embodiments, the base station may transmit a paging message to the UE, and the UE decides to initiate the 2-step SDT based on the relative value of the currently measured RSRP and the preset RSRP threshold. Unlike the above-mentioned case where the UE proactively initiates the small data transmission procedure, the RRC message transmitted by the UE to the base station in S221 may not carry uplink small data and may optionally further carry cause information for triggering the MT-EDT. Correspondingly, the base station may receive the downlink small data transmitted by the core network. The RRC response message transmitted by the base station to the UE in S223 may carry the downlink small data.

[0204] This is not limited to the above example. In some other embodiments, the base station may send both msgB and the RRC response message to the UE.

[0205] In some embodiments, after starting RA-SDT, the UE cannot transmit msg3 or msgA only once to complete the transmission of small data, and the UE may complete the transmission of small data through a subsequent transmission. This subsequent transmission may be performed after the UE receives the contention resolution and before the base station transmits an RRC response message to the UE, for example, between S114 and S115 in FIG. 5 and between S212 and S213 in FIG. 7. A specific example is as follows:

[0206] Example 1: The RA-SDT currently initiated by the UE is for the transmission of one small data (e.g., one instant messaging message). When the UE initiates the 4-step SDT, the size of the UL grant indicated in the RAR by the base station is less than the sum of the sizes of the transmission resources of the small data and the RRC request message, or when the UE initiates the 2-step SDT, the size of the transmission resources obtained by the UE from the broadcast message is less than the sum of the sizes of the transmission resources of the random access preamble, the small data, and the RRC request message. In this case, the UE may first transmit some data of the small data via msg3 or msgA, and then perform the transmission of the remaining data of the small data through a subsequent transmission. For example, after sending a contention resolution to the UE, the base station may dynamically schedule uplink resources for the UE to perform a subsequent transmission.

[0207] Example 2: The RA-SDT currently initiated by the UE is for transmitting multiple small data. After the small data arrives, the UE may initiate a 4-step SDT or a 2-step SDT and perform the transmission of the small data via msg3 or msgA. However, in this SDT procedure, the UE obtains new small data, and the UE may perform the transmission of the new small data through a subsequent transmission. For example, after sending a contention resolution to the UE, the base station may dynamically schedule uplink resources for the UE to perform a subsequent transmission.

[0208] 9 is an example schematic flow chart showing a CG-SDT procedure in a user plane. The procedure shown in FIG. 9 may include, but is not limited to, the following steps:

[0209] S311: The UE sends an RRC request message and uplink small data to the base station on preconfigured resources.

[0210] For example, the pre-configured resource is a configured grant resource type 1 (CG Type 1) or PUR. CG TYPE 1 may be an uplink resource directly configured by the RRC layer, including but not limited to the time-frequency resource location and resource periodicity in the uplink resource.

[0211] In some embodiments, if both the base station and the UE support CG-SDT and the UE meets the conditions for using CG-SDT, the UE may perform S311 without performing RA. The conditions for using CG-SDT include, for example, the UE being in a non-RRC connected state, the UE having a requirement to transmit uplink small data, the UE having pre-configured resources, the UE meeting RSRP conditions, and the UE having a valid TA.

[0212] In some embodiments, the conditions for the UE to determine the use of CG-SDT include at least one of the following conditions:

[0213] Condition 1: TAT is working, specifically, the UE's TA is valid, and the UE and the base station are in an uplink synchronization state, which may indicate that CG-SDT is valid; otherwise, CG-SDT is invalid.

[0214] Condition 2: When the TAT is working, the current RSRP in the UE exceeds a preset first RSRP threshold (RSRP 1 for short), which may represent that the CG-SDT is valid. Optionally, RSRP 1 may be the RSRP at which the UE can start SDT transmission. Specifically, if the current RSRP in the UE exceeds the preset RSRP 1, it indicates that the UE is close to the base station and the channel quality is good. If the CG-SDT is executed, the success rate will be high and the CG-SDT is valid. If the current RSRP in the UE is equal to or less than the preset RSRP 1, it indicates that the UE is far away from the base station and the channel quality is poor. If the CG-SDT is executed, the success rate will be low. RSRP 1 may be set by the base station for both the CG-SDT and the RA-SDT.

[0215] Condition 3: In the preset time period when TA is last valid, the increment or decrement of RSRP in the UE is less than or equal to a preset second RSRP threshold (abbreviated as RSRP 2), which may indicate that CG-SDT is valid. That is, whether the UE moves can be determined based on the increment or decrement of RSRP in the UE. If the increment or decrement of RSRP is equal to or greater than RSRP 2, it indicates that the UE moves or moves a longer distance than the UE position in the time period when TA is last valid. If CG-SDT is executed, the success rate is low and CG-SDT is invalid. If the increment or decrement of RSRP is less than RSRP 2, it indicates that the UE does not move or moves a smaller distance than the UE position in the time period when TA is last valid. If CG-SDT is executed, the success rate is high and CG-SDT is valid.

[0216] Condition 4: When the base station configures CG-SDT on the SUL and / or NUL, the UE needs to compare the current RSRP with a third RSRP threshold (RSRP 3 for short) preset by the base station to determine whether the CG-SDT configured on the SUL is valid or the CG-SDT configured on the NUL is valid. Optionally, assuming that the CG-SDT is configured on both the SUL and NUL, the UE compares the current RSRP and RSRP 3. If the current RSRP is less than RSRP 3, the UE selects the CG-SDT on the SUL. If the current RSRP is equal to or greater than RSRP 3, the UE selects the CG-SDT on the NUL. Specifically, when the base station configures CG-SDT on both the SUL and NUL, if the current RSRP on the UE is less than RSRP 3, it indicates that the UE is far away from the base station and needs to use the CG-SDT configured on the SUL. That is, the CG-SDT on the SUL is valid and the CG-SDT on the NUL is invalid. If the current RSRP in the UE is equal to or greater than RSRP 3, it indicates that the UE is relatively close to the base station and should use the CG-SDT configured on the NUL. That is, the CG-SDT on the NUL is valid and the CG-SDT on the SUL is invalid. Optionally, assuming that the base station configures the CG-SDT only on the SUL, the UE compares the current RSRP with RSRP 3. If the current RSRP is less than RSRP 3, the UE selects the CG-SDT on the SUL. In this case, the CG-SDT is valid. If the current RSRP is equal to or greater than RSRP 3, the UE cannot use the CG-SDT, in other words, the CG-SDT on the SUL is invalid. That is, the base station configures the CG-SDT on the SUL, and if the UE is far away from the base station, the UE can use the CG-SDT on the SUL, otherwise the CG-SDT on the SUL is invalid. Optionally, assuming that the base station configures the CG-SDT only on the NUL, the UE compares the current RSRP with RSRP 3. If the current RSRP is less than RSRP 3, the UE cannot use CG-SDT.If the current RSRP is equal to or greater than RSRP 3, the UE selects the CG-SDT in NUL, in other words, the CG-SDT in NUL is valid, i.e., the base station configures the CG-SDT in NUL, and if the UE is close to the base station, the UE can use the CG-SDT in NUL, otherwise the CG-SDT in NUL is invalid.

[0217] Condition 5: The UE is within the coverage of the base station, and the base station configures a CG resource for the UE that is for CG-SDT.

[0218] In some embodiments, before S311, the UE may further request the base station to configure pre-configured resources used to initiate CG-SDT. For example, a UE in an RRC CONNECTED state sends a CG-SDT resource request message to the base station. The CG-SDT resource request message is used to request the base station to configure CG-SDT. For example, in LTE, the UE sends PUR configuration request information (PURConfigurationRequest message) to the base station.

[0219] Optionally, a UE in an RRC CONNECTED state may send a CG-SDT resource request message to a base station at any time. Optionally, a UE in an RRC CONNECTED state may determine that there may be small data in the future and send a CG-SDT resource request message to a base station. Optionally, a UE in an RRC CONNECTED state may not need to perform data transmission to a base station within a preset time period. A UE determines that the UE is going to transition to a non-RRC connected state. When the UE is in a non-RRC connected state, the UE may send a CG-SDT resource request message to a base station to perform small data transmission.

[0220] In some embodiments, after the base station receives configuration request information (e.g., a CG-SDT resource request message or a PUR Configuration Request message, etc.), when the base station instructs the UE to switch from an RRC CONNECTED state to a non-RRC CONNECTED state, the RRC response message sent by the base station to the UE may carry detailed configuration information of the CG-SDT. For example, when the base station instructs the UE to switch from an RRC CONNECTED state to an RRC INACTIVE state, the RRC response message is a RRCRelease message, and the RRCRelease message may carry detailed configuration information of the CG resource. For example, when the base station instructs the UE to switch from an RRC CONNECTED state to an RRC IDLE state, the RRC response message is a RRCRelease message, and the RRCRelease message may carry detailed configuration information of the PUR.

[0221] This is not limited to the above enumerated cases. In some other embodiments, after configuring the CG-SDT for the UE, the base station may send an RRC response message carrying release instruction information to the UE to release the configured CG-SDT. For example, the RRCRelease message may carry the release instruction information of the CG resource. For example, the RRCConnectionRelease message may carry the release instruction information of the PUR.

[0222] In some other embodiments, the UE may not send a CG-SDT resource request message to the network equipment, and the network equipment may directly configure the CG-SDT resource for the UE. For example, the network equipment may configure the CG-SDT resource for the UE based on the past communication service situation of the UE.

[0223] In some embodiments, the UE may send uplink small data and an RRC request message to the base station to initiate an RRC connection resumption procedure for the CG-SDT. In some embodiments, in the RRC request message for initiating the RRC connection resumption procedure for the CG-SDT, the resumeCause IE may be set to mo-data.

[0224] In some embodiments, the UE first initializes an RRC connection resumption procedure for the SDT and then sends an RRC request message to the base station based on the CG-SDT. In some embodiments, the UE starts a first timer when it initializes the RRC connection resumption procedure for the SDT. In some other embodiments, the UE starts the first timer when it sends uplink small data and an RRC request message to the base station based on the CG-SDT.

[0225] This is not limited to the above-mentioned exemplary case. In some other embodiments, the UE may transmit only small data in the CG-SDT procedure. For example, if the resource indicated by the CG-SDT configuration is a dedicated resource configured by the network equipment for the UE and is not a shared resource, the UE may transmit only small data in the resource indicated by the CG-SDT configuration in the CG-SDT procedure. In this way, the network equipment may identify the UE that transmits the small data based on the resource for receiving the small data. As another example, if the resource indicated by the CG-SDT configuration is a shared resource configured by the network equipment for multiple UEs, the UE may transmit the small data and the RRC request message on the resource indicated by the CG-SDT configuration in the SDT procedure. In this way, the network equipment may identify the UE by using the RRC message.

[0226] For an explanation of the RRC request message and the uplink small data, please refer to the explanation of the RRC request message and the uplink small data in S113 in Figure 5. The details will not be described again.

[0227] S312: The base station sends a feedback response message to the UE.

[0228] In some embodiments, the base station transmits a feedback response message to the UE in response to the RRC request message transmitted by the UE. In some embodiments, the feedback response message indicates that transmission of the RRC request message is successful. In some embodiments, the feedback response message indicates that transmission of the RRC request message and uplink small data transmitted with the RRC request message is successful. In some embodiments, the feedback response message indicates that transmission of the uplink small data is successful.

[0229] In some embodiments, the feedback response message is a Layer 1 Ack message, ie, a physical layer ACK.

[0230] In some embodiments, the feedback response message is a Downlink Feedback Information (DFI), or CG-DFI.

[0231] In some embodiments, the feedback response message is a MAC CE at the MAC layer.

[0232] In some embodiments, the feedback response message is an RRC message at the RRC layer.

[0233] S313: The base station sends an RRC response message to the UE.

[0234] In some embodiments, if the core network has downlink small data to send to the UE, the core network may send the downlink small data to the base station, which may then send the downlink small data along with an RRC response message to the UE.

[0235] For an explanation of the RRC response message, please refer to the explanation of the RRC response message in S115 in Figure 5. Details will not be explained again.

[0236] In some embodiments, the RRC response message may include a CG-SDT configuration, for example, the CG-SDT configuration in S311 is used by the UE to perform the small data transmission in S311, and the CG-SDT configuration indicated by the RRC response message in S313 is used by the UE to perform the next small data transmission.

[0237] In some embodiments, when the feedback response message in S312 is an RRC message in the RRC layer, the feedback response message in S312 and the RRC response message in S313 may be the same message, that is, the feedback response message may be an RRC response message, in other words, S312 and S313 are the same step.

[0238] 10 is an example schematic flow chart illustrating a CG-SDT procedure in the control plane. The procedure illustrated in FIG. 10 may include, but is not limited to, the following steps:

[0239] S321: The UE sends an RRC request message carrying uplink small data to the base station on a preconfigured resource.

[0240] Specifically, S321 is similar to S311 in FIG. 9, with the difference being that the uplink small data is not transmitted together with the RRC request message, but is instead carried and transmitted in the RRC request message.

[0241] S322: The base station sends a feedback response message to the UE.

[0242] S323: The base station sends an RRC response message to the UE.

[0243] Specifically, S322 and S323 are similar to S312 and S313 in FIG. 9, and the details will not be described again.

[0244] 9 and 10 are described by using an example in which S311 and / or S321 are executed when the UE transmits uplink small data to the base station, in other words, when the UE actively initiates the small data transmission procedure. However, in a specific implementation, there is also a case in which the UE passively initiates the small data transmission procedure based on the instruction of the base station. The transmission procedure in this case is similar to the transmission procedure shown in FIG. 9 and FIG. 10, and the differences are specifically described as follows:

[0245] Before S311, if the core network has downlink small data to be transmitted to the UE, the core network may transmit a paging message to the base station. In some embodiments, the paging message may carry data amount information of the downlink small data. In some embodiments, the base station may transmit the paging message to the UE, which causes the UE to initiate CG-SDT. Unlike the above-mentioned case where the UE proactively initiates the small data transmission procedure, in S311, the UE may transmit only an RRC request message to the base station, and may not transmit uplink small data. Optionally, the RRC request message may further carry cause information for triggering MT-EDT. Correspondingly, the base station may receive the downlink small data transmitted by the core network, and in S313, the base station may transmit an RRC response message and the downlink small data to the UE.

[0246] Similarly, before S321, if the core network has downlink small data to be transmitted to the UE, the core network may transmit a paging message to the base station. In some embodiments, the paging message may carry data amount information of the downlink small data. In some embodiments, the base station may transmit a paging message to the UE, which causes the UE to initiate CG-SDT. Unlike the above-mentioned case where the UE proactively initiates the small data transmission procedure, the RRC message transmitted by the UE to the base station in S321 may not carry uplink small data and may optionally further carry cause information for triggering MT-EDT. Correspondingly, the base station may receive the downlink small data transmitted by the core network. The RRC response message transmitted by the base station to the UE in S323 may carry the downlink small data.

[0247] It may be understood that the NG-RAN manages the RNA of a UE in an RRC INACTIVE state, and the NG-RAN may obtain the RNA in which the UE is located.

[0248] In some embodiments, one RNA may be configured by a previous serving base station for a UE in RRC INACTIVE state. One RNA may cover one or multiple cells, and the RNA may be included in a core network registration area. In some embodiments, there is an Xn connection between base stations in the same RNA.

[0249] In some embodiments, the base station may configure RNA-related information, e.g., a cell list or a RAN area list, for the UE based on a RAN-NotificationAreaInfo IE in an RRC response message (e.g., an RRCRelease message, etc.) sent to the UE.

[0250] Below, two RNA configuration cases are illustrated by using examples.

[0251] Case 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, and one or more cells included in the cell list constitute an RNA configured by the base station for the UE.

[0252] Case 2: The base station configures a RAN area list for the UE. In some embodiments, one or more RAN areas included in the RAN area list configure the RAN configured by the base station for the UE. In some embodiments, the base station configures a RAN area identifier (ID) (RAN area ID) for the UE. Each RAN area is a subset of or equal to a core network tracking area (CN tracking area). Each RAN area is identified by a RAN area ID, and each RAN area includes a tracking area code (TAC). The TAC identifies the tracking area to which the RAN area belongs. In some embodiments, each RAN area may include a RAN area code, and the RAN area code may be used to identify the region of the RAN area within the scope of the tracking area. In some embodiments, each cell and corresponding base station may broadcast one or more RAN area IDs in the system information.

[0253] It may be understood that a UE in an RRC INACTIVE state may trigger an RNA update (RNAU). Optionally, after being configured with an RNA, the UE may trigger an RNAU to inform the network equipment of the UE's mobility-related state, such as the terminal's current RNA state, for example, the RNA in which the terminal is currently located, whether the terminal is in an RNA configured by a base station for the UE, or the cell in which the UE is currently located.

[0254] Below, we explain two cases of triggering RNAU by using examples.

[0255] Case 1: The UE may periodically trigger the RNAU, and the triggering of the RNAU may be controlled by a second timer. For example, the second timer is T380 defined in 38.321 in the 3GPP protocol, and when T380 expires, it triggers the RNAU. In some embodiments, when the base station sends a first RRC response message to the UE, it sets 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 starting condition of the second timer includes the UE receiving a first RRC response message, for example, an RRCRelease message, an RRC release with suspend config message, or another RRC message having the same function but not standardized in 3GPP. In some embodiments, when the second timer expires, the UE triggers the 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 stop condition of the second timer includes the UE receiving a second RRC response message, such as an RRCResume message, an RRCSetup message, an RRCRelease message, or another RRC message having the same functionality but not standardized by 3GPP.

[0256] Case 2: 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 may trigger RNAU if the serving cell of the UE does not belong to the configured RNA. For example, the UE may trigger RNAU if the serving cell obtained through cell reselection that occurred to the UE does not belong to the configured RNA. For example, the terminal moves and cell reselection occurs. In some embodiments, after the UE reads SIB1 in the serving cell (e.g., a new serving cell obtained through cell reselection), the UE may trigger RNAU if the cell provided by SIB1 does not belong to the cell list configured by the base station for the UE or the RAN area provided by SIB1 does not belong to the RAN area list configured by the base station for the UE. For example, the UE may trigger RNAU if the cell ID read by the UE from SIB1 does not belong to the cell ID included in the cell list configured by the base station for the UE and included in the RAN-NotificationAreaInfo IE. For example, if the TAC of a cell read by the UE from SIB1 does not belong to the TACs included in the RAN area list configured by the base station for the UE and in the RAN-NotificationAreaInfo IE, the UE may trigger an RNAU.

[0257] In the following, an implementation for performing RNAU is described by using an example.

[0258] In some embodiments, when the UE triggers the RNAU, the UE may initiate an RRC connection resume procedure for the RNAU. In some embodiments, the UE initiating the RRC connection resume procedure for the RNAU may include: the RRC layer of the UE initiating a procedure requiring the resume of a suspended RRC connection. In some embodiments, the UE initiating the RRC connection resume procedure for the RNAU may include: the UE sending an RRC resume request message, such as an RRCResumeRequest message or an RRCResumeRequest1, to the base station, and the resumeCause IE in the RRC request message may be set to rna-Update.

[0259] In some embodiments, the UE initiating the RRC connection resumption procedure for the RNAU may further include initializing the RRC connection resumption procedure, and may specifically include: if an emergency service is currently running, the UE may select an Access Category as 2 and set a resumeCause IE in an RRC request message sent in the RRC connection resumption procedure to emergency; if an emergency service is not currently running, the UE may select an Access Category as 8. The access category can be used for access barring check. Each access request can be associated with an access category, which allows the base station to control the access request of the UE. In some embodiments, the access request can be an RRC connection resumption request initiated by the UE.

[0260] In some embodiments, during the initialization of the RRC connection resumption procedure, the UE selects an access category. Then, the UE may perform a unified access control (UAC) procedure and then determine whether the access attempt is barred. For example, each access attempt corresponds to an access category. For example, the access attempt is for initiating an RRC connection resumption procedure for an RNAU. In this case, the access category is 2 or the access category is 8. If the access attempt is barred, the UE cannot initiate an RRC connection resumption procedure for an RNAU. If the access attempt is not barred, the UE can initiate an RRC connection resumption procedure for an RNAU. Specific cases are as follows:

[0261] Optionally, if the access attempt is barred, the UE may set a first variable to a first value and stop the access attempt.

[0262] Optionally, if the access attempt is barred, the UE may start a timer T390. For example, the UE starts a timer T390 for an access category corresponding to the barred access attempt. When the timer T390 of the access category runs, the UE considers the access attempt to be barred. When the timer T390 of the access attempt expires, e.g., when the timer T390 of the access attempt is not running, the UE considers the barring corresponding to the access category to be relaxed. For example, the access category is 2 or the access category is 8.

[0263] The value of the first variable is a first value or a second value. For example, the first variable indicates whether there is a pending RNA-Update, the first value being true, and the second value being false. In some embodiments, when the value of the first variable is the first value, it may indicate that there is a pending RNA-Update procedure. In some embodiments, when the value of the first variable is the second value, it may indicate that there is no pending RNA-Update procedure. In some embodiments, when the value of the first variable is the first value, it may indicate that an RNAU has been triggered but has not been successfully performed (this may be understood as an RRC connection resumption procedure for an RNAU not being successfully performed).

[0264] If the access attempt is not prohibited, the UE may continue to perform initialization related to the RRC connection resumption procedure, such as applying a default physical layer configuration, a default SRB1 configuration, and a default MAC layer configuration, and the UE may set the first variable to a second value. The UE may then start transmitting an RRC request message, such as restoring the RRC configuration, reconfiguring the PDCP entity of SRB1, and resuming SRB1, and the UE may perform transmitting an RRC request message to the lowest layer of the UE (the lowest layer is relative to the RRC layer, such as the MAC layer or the physical layer). For example, after the RRC layer of the UE performs the initialization procedure described above, the RRC layer performs transmitting an RRC request message to the MAC layer, and then the MAC layer transmits the RRC request message. In some embodiments, no transmission resources are configured for a UE in a non-RRC connected state. Upon receiving a transmission request transmitted by the RRC layer, the MAC layer may initiate an RA to transmit an RRC request message that is for the RNAU, such as transmitting an RRC request message in msg3 described above or msgA described above. In some other embodiments, the UE in the non-RRC connected state has pre-configured resources, such as CG resources or PUR. The description of the pre-configured resources is similar to the description of the pre-configured resources in FIG. 9 and FIG. 10. Upon receiving the transmission request sent by the upper layer, the lower layer may send an RRC request message for the RNAU on the pre-configured resources. For example, the lower layer is a MAC layer and the upper layer is an RRC layer. For example, the lower layer is a physical layer and the upper layer is an RRC layer. For example, the lower layer is a physical layer and the upper layer is a MAC layer. After receiving the transmission request sent by the RRC layer, the MAC layer indicates the transmission request to the physical layer. The resumeCause IE in the RRC request message for the RNAU is set to rna-Update. In some embodiments, the base station may receive the RRC request message for the RNAU and sent by the UE, and confirm that the UE is currently requesting the RNAU, so as to perceive the current status of the UE, such as a mobility status.

[0265] In some embodiments, the base station successfully receives an RRC request message for RNAU and sent by the UE. The base station may send a third RRC response message to the UE after contention resolution is successful (e.g., after sending a contention resolution message to the UE). The third RRC response message may be, for example, an RRCRelease message, an RRCRelease message with suspend indication, an RRCResume message, or other RRC messages having the same function but not standardized in 3GPP. Optionally, upon receiving the third RRC response message, the UE may consider RNAU to be successful. A specific example is as follows.

[0266] Example 1: When a UE is served by a current base station (sometimes called a new base station), it performs RNAU, but the UE's context is stored in a previous base station (sometimes called an old base station). The old base station may send the UE's context to the new base station via the Xn interface. After acquiring the UE's context, the new base station may send an RRC response message to the UE, for example, send an RRCRelease message to enable the UE to transition to an RRC IDLE state, send an RRCRelease message with suspend indication to enable the UE to transition to an RRC INACTIVE state, or send an RRCResume message to enable the UE to transition to an RRC CONNECTED state.

[0267] Example 2: When the UE is served by the current base station (sometimes called the new base station), it starts RNAU, but the UE's context is stored in the previous base station (sometimes called the old base station). The old base station does not transmit the UE's context to the new base station. In this case, the UE's RRC state is controlled by the old base station, and the old base station may indirectly transmit an RRC response message to the UE based on the Xn interface message, specifically, the RRC response message is transmitted to the new base station, and then the new base station forwards the RRC response message, for example, forwards an RRCRelease message to allow the UE to transition to an RRC IDLE state, or forwards an RRCRelease message with a suspend indication to allow the UE to transition to an RRC INACTIVE state.

[0268] In some other embodiments, the base station sends a fourth RRC response message to the UE. For example, if the base station fails to receive an RRC request message for RNAU and sent by the UE, the base station may send a fourth RRC response message to the UE after successful contention resolution. The fourth RRC response message may be, for example, an RRCConnectionReject message, an RRCReject message, or other RRC messages having the same function but not standardized in 3GPP. Optionally, after receiving the fourth RRC response message, the UE may return to an RRC INACTIVE state. Optionally, when the UE receives the fourth RRC response message, the UE may consider the RRC resume request for RNAU to be rejected and set the first variable to a first value.

[0269] In some embodiments, after the UE receives the fourth RRC response message, if a wait time is configured in the fourth RRC response message, the UE starts a timer T302, and the duration of the timer T302 is equal to the wait time. If the timer T302 is running and the access category is not 2 or 0, the UE considers the access attempt to be barred. If the timer T302 expires and the T390 corresponding to the access category is not running, the UE considers the barring corresponding to the access category to be relaxed. It should be noted that the timer T302 barrs the UE's request and does not identify the UE's access category.

[0270] In some embodiments, the UE now initiates an RRC connection resumption procedure for RNAU and selects the access category as 8. If the access attempt is not prohibited when the RRC connection resumption procedure for RNAU is initialized, the UE may continue performing the initialization related to the RRC connection resumption procedure and transmit an RRC request message corresponding to the RRC connection resumption procedure for RNAU without starting T390 corresponding to access category 8. When the base station transmits a fourth RRC response message to the UE, in which a waiting time is configured, the UE starts a timer T302. If T390 corresponding to access category 8 is not running when timer T302 expires, the UE considers that the prohibition corresponding to access category 8 is relaxed.

[0271] In some embodiments, the UE may set the first variable to a first value to continue execution of the RNAU if the current RNAU is triggered but not successfully executed. For example, after the UE triggers the RNAU, if an access attempt is prohibited or a fourth RRC response message (e.g., an RRCReject message, etc.) is received in the RRC connection resumption procedure for the RNAU, the UE may set the first variable to a first value. In some embodiments, when the first variable is set to a first value, the UE may continue attempting to initiate the RRC connection resumption procedure for the RNAU. In some embodiments, when the prohibition corresponding to the access category 8 or the access category 2 is relaxed and the first variable is set to a first value without the higher layer (e.g., the NAS layer, etc.) requesting the resumption of the RRC connection for data transmission, for example, the UE may continue initiating the RRC connection resumption procedure for the RNAU.

[0272] When a UE currently in a non-RRC connected state and a base station execute SDT, RNAU may be triggered. In this case, the terminal may stop the currently executed SDT and execute RNAU. As a result, the transmission of small data in SDT is affected. Specific examples are as follows.

[0273] Example 1: Before the UE and the base station perform RA-SDT, the UE receives an RRCRelease message sent by the base station and starts a second timer (e.g., T380, etc.). Then, the UE starts an RRC connection resumption procedure for SDT, for example, the 4-step SDT shown in Figures 5 and 6, or the 2-step SDT shown in Figures 7 and 8, and the second timer is started before the UE transmits a random access preamble. If the second timer expires before the UE receives a contention resolution message sent by the base station, in other words, if an RNAU is triggered before the UE receives a contention resolution message sent by the base station, this case can be understood as a new RA for RNAU being triggered in the current RA execution procedure for SDT. In this case, whether to perform RNAU depends on the implementation of the UE, and specifically, the implementation of the UE decides whether to continue the current RA procedure for SDT or to perform a new RA for RNAU. When the UE performs a new RA for RNAU, the uplink small data and the downlink small data may not be transmitted or may fail to be transmitted, for example, the uplink small data transmitted with msg3 or msgA and the downlink small data transmitted with the RRC response message. If the second timer expires after the UE receives the contention resolution message transmitted by the base station, in other words, if the RNAU is triggered after the UE receives the contention resolution message transmitted by the base station, the UE must abandon the currently running RA-SDT procedure and start the RRC connection resumption procedure for RNAU. In this way, the uplink small data and the downlink small data may not be transmitted or may fail to be transmitted, for example, the uplink small data and / or the downlink small data that need to be transmitted in the subsequent transmission, and the downlink small data transmitted with the RRC response message.

[0274] Example 2: Before the UE and the base station perform CG-SDT, the UE receives an RRCRelease message sent by the base station and starts a second timer (e.g., T380, etc.). The UE then starts an RRC connection resumption procedure for SDT, e.g., the CG-SDT shown in Figures 9 and 10, and the second timer may start before the UE transmits an RRC request message and / or uplink small data. If the second timer expires, the UE needs to abandon the currently running CG-SDT procedure and start an RRC connection resumption procedure for RNAU. In this way, the uplink small data and the downlink small data, e.g., the uplink small data and / or the downlink small data that need to be transmitted in a subsequent transmission, as well as the downlink small data transmitted with the RRC response message, may not be transmitted or may fail to be transmitted.

[0275] An embodiment of the present application provides a transmission control method that can be applied to a communication system. The communication system includes, for example, a terminal and a network device. When the terminal and the network device execute SDT, RNAU may not be triggered to avoid affecting the transmission of small data. For example, the impact includes an increase in transmission delay, and also an increase in power consumption and signaling overhead when SDT is started again thereafter. When the terminal and the network device execute SDT, the network device does not need to additionally execute RNAU to obtain the RNA where the terminal is located and to inform the network device of the current status of the terminal.

[0276] The following describes an example in which the network device obtains the RNA in which the terminal is located when the terminal and the network device perform the SDT. Example 1: The base station where the terminal starts the SDT this time is the same as the base station where the terminal received the RRCRelease message last time. In other words, if the terminal is served by the same base station, it receives the RRCRelease message and starts the RRC connection resumption procedure for the SDT. Optionally, the base station where the terminal received the RRCRelease message last time may be the base station that configures the RNA for the terminal, and the base station may configure the related information of the RNA for the terminal through the RRCRelease message, that is, if the terminal is configured by the RNA and is served by the same base station, it starts the SDT. The base station stores the context of the terminal. The base station may be aware of the RNA in which the terminal is located. For example, the base station may confirm the RNA previously configured for the terminal based on the context that belongs to the terminal and is stored by the base station. In this case, the terminal that starts the SDT will not move beyond the range of the configured RNA. Therefore, the base station may confirm that the RNA in which the terminal is located is the configured RNA.

[0277] Example 2: The base station where the terminal starts the SDT this time (may be called a new base station) is different from the base station where the terminal received the RRCRelease message last time (may be called an old base station). In other words, when the terminal is served by the new base station, it starts the RRC connection resumption procedure which is for the SDT. Optionally, the old base station where the terminal received the RRCRelease message last time may be the base station that configures the RNA for the terminal, and the old base station may configure the related information of the RNA for the terminal through the RRCRelease message. The new base station may perceive the RNA where the terminal is located. For example, the new base station may obtain the context of the terminal from the old base station, and the new base station may check whether the terminal moves beyond the range of the RNA configured for the terminal by the old base station based on the obtained context of the terminal and / or the information on the old base station. For example, if the RNA configuration obtained by the new base station from the context of the terminal does not include an RNA list or a cell list corresponding to the new base station, the new base station may check that the terminal has moved beyond the range of the configured RNA, and if not, the new base station may check that the terminal has not moved beyond the range of the configured RNA. As another 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, the new base station may determine that the terminal has moved beyond the range of the configured RNA, otherwise, the new base station may determine that the terminal has not moved beyond the range of the configured RNA.

[0278] Based on the above description, the transmission control method provided in the embodiment of the present application is described below. The method can be applied to the communication system shown in Figure 1. The network device and the terminal in the method can be the network device 120 and the UE 130 shown in Figure 1.

[0279] In the following embodiment, an example of a transmission procedure based on a user plane protocol stack is used for description. For the first timer and the second timer in the following embodiment, please refer to the description of the first timer and the second timer described above.

[0280] In a possible implementation, when the terminal is in a non-RRC connected state, if a first preset condition is satisfied, the terminal performs an RRC connection resumption procedure for RNAU. For a description of the RRC connection resumption procedure for RNAU, refer to the description of the initiation of the RRC connection resumption procedure for RNAU in the above-mentioned implementation for performing RNAU.

[0281] In some embodiments, the first preset condition includes that the second timer expires and the first timer is not running. A specific example is shown in FIG. 11. The first preset condition is the first condition in FIG. 11. In some embodiments, the first preset condition includes that the terminal receives SIB1 of the first serving cell, the first serving cell does not belong to the configured RNA, and the first timer is not running. A specific example is shown in FIG. 13. The first preset condition is the second condition in FIG. 13. An example of the above description is as follows.

[0282] Example 1: When the terminal is in an RRC INACTIVE state, when a second timer (e.g., T380, etc.) expires without a first timer (e.g., T3XX, etc.) running, or when the terminal's serving cell does not belong to a configured RNA without a first timer (e.g., T3XX, etc.) running, the terminal may initiate an RRC connection resumption procedure and set the resumeCause IE in the RRC request message for initiating the RRC connection resumption procedure to rna-Update.

[0283] Example 2: When the terminal is in the RRC INACTIVE state, if the second timer (e.g., T380, etc.) expires or the terminal's serving cell does not belong to the configured RNA, and if the first timer (e.g., T3XX, etc.) is not running, the terminal may initiate an RRC connection resumption procedure and set the resumeCause IE in the RRC request message for initiating the RRC connection resumption procedure to rna-Update.

[0284] Optionally, performing an RRC connection resume procedure for an RNAU may include: initiating an RRC connection resume procedure; and setting a resumeCause IE in an RRC request message for initiating an RRC connection resume procedure to rna-Update.

[0285] 11 is a schematic flow chart illustrating a transmission control method according to an embodiment of the present application. The method includes, but is not limited to, the following steps:

[0286] S401: The terminal starts a second timer.

[0287] In some embodiments, S401 is an optional step.

[0288] In some embodiments, the terminal receives a first RRC response message and 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 a duration of the second timer. The first RRC response message is, for example, an RRCRelease message, an RRCRelease with suspend configuration message, or another RRC message having the same functionality but not standardized by 3GPP.

[0289] S402: The terminal triggers the RNAU when a first condition is satisfied.

[0290] In some embodiments, when the terminal is in a non-RRC connected state, the terminal triggers the RNAU when the first condition is met. Optionally, the non-RRC connected state is an RRC INACTIVE state.

[0291] In some embodiments, the first condition includes the terminal being in an RRC INACTIVE state.

[0292] In some embodiments, the step of triggering the RNAU is to perform an RRC connection resume procedure for the RNAU. Optionally, when performing the RRC connection resume procedure for the RNAU, the terminal may send an RRC request message to a network device, and the resumeCause IE in the RRC request message is rna-Update.

[0293] Specifically, the first condition includes the second timer expiring and the first timer not running. Optionally, the first timer not running means: the first timer is not started.

[0294] 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 RNAU. If the first timer is not running, the terminal triggers RNAU.

[0295] In some embodiments, if the second timer expires and the terminal does not have an SDT requirement when the second timer is not running, the terminal may trigger an RNAU. Optionally, the first timer not running may indicate that the terminal does not have an SDT requirement. Optionally, when the second timer is running, the first timer is not running. An example is shown in FIG.

[0296] FIG. 12 shows an example of a sequence diagram.

[0297] As shown in FIG. 12, the horizontal axis is time (t). 1 At time t, a second timer is started (e.g., when a first RRC response message is received) and is timed at a second time t 2 At t, the second timer expires. 1 <t 2 The second timer runs between the first time point and the second time point, the first timer does not run between the first time point and the second time point, and the first timer is not started between the first time point and the second time point. At the second time point, the second timer expires and the first timer is not running. In this case, the terminal may trigger the RNAU.

[0298] Optionally, the above mentioned RRC connection resume procedure which is for SDT includes: initiating an RRC connection resume procedure; and setting a resumeCause IE in an RRC request message for initiating an RRC connection resume procedure to mo-data.

[0299] 13 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. The method includes, but is not limited to, the following steps:

[0300] S501: The terminal starts a first timer.

[0301] In some embodiments, S501 is an optional step.

[0302] In some embodiments, the terminal starts the first timer when starting the RRC connection resumption procedure for the SDT. Optionally, the terminal starts the first timer when transmitting an RRC request message and / or uplink small data to the network equipment. For example, in the procedures shown in Figures 5 to 8, the terminal starts the first timer when transmitting msg3 or msgA to the network equipment based on the RA-SDT. Also, for example, in the procedures shown in Figures 9 and 10, the terminal starts the first timer when transmitting an RRC request message and / or uplink small data to the network equipment based on the CG-SDT.

[0303] S502: Cell reselection occurs in the terminal.

[0304] In some embodiments, S502 is an optional step.

[0305] In some embodiments, cell reselection occurs when the terminal and the network equipment are performing an SDT procedure. In some embodiments, cell reselection occurs at the terminal when the first timer is running, and the terminal stops the first timer.

[0306] In some embodiments, cell reselection occurs in a terminal, and the terminal switches from a first cell to a second cell. In other words, the serving cell obtained by the cell reselection occurring in the terminal is the second cell, hereafter referred to as the first serving cell. In some embodiments, the first serving cell of the terminal does not belong to a configured RNA, and the RNA is configured by the network equipment for the terminal before the cell reselection occurs in the terminal.

[0307] In some embodiments, after cell reselection occurs, the terminal receives SIB1 of the current serving cell and determines a first serving cell based on the SIB1, where SIB1 indicates the first serving cell. In some embodiments, the terminal determines based on SIB1 that the first serving cell does not belong to a configured RNA, where the RNA is configured by the network device for the terminal before cell reselection occurs in the terminal. A specific example is as follows.

[0308] Example 1: The terminal reads the cell ID of the first serving cell from SIB1, and if the read cell ID of the first serving cell is included in the cell list configured by the network equipment for the terminal and does not belong to the cell ID in the RAN-NotificationAreaInfo IE, the terminal determines that the first serving cell does not belong to the configured RAN.

[0309] Example 2: The terminal reads the TAC of the first serving cell from SIB1, and if the read TAC of the first serving cell is included in the RAN area list configured by the network equipment for the terminal and does not belong to the TAC in the RAN-NotificationAreaInfo IE, the terminal determines that the first serving cell does not belong to the configured RAN.

[0310] In some embodiments, after cell reselection occurs on the terminal, the terminal is in a non-RRC connected state. Optionally, the non-RRC connected state is an RRC INACTIVE state.

[0311] S503: The terminal triggers the RNAU if a second condition is met.

[0312] In some embodiments, when the terminal is in a non-RRC connected state, the terminal triggers the RNAU when the second condition is met. Optionally, the non-RRC connected state is an RRC INACTIVE state.

[0313] In some embodiments, the second condition includes the terminal being in an RRC INACTIVE state after a cell reselection has occurred on the terminal.

[0314] In some embodiments, the step of triggering the RNAU is to perform an RRC connection resume procedure for the RNAU. Optionally, when performing the RRC connection resume procedure for the RNAU, the terminal may send an RRC request message to a network device, and the resumeCause IE in the RRC request message is rna-Update.

[0315] Optionally, the second 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. In some embodiments, the first serving cell is a serving cell obtained through cell reselection occurring at the terminal. In some embodiments, the first serving cell is a cell indicated by SIB1 received by the terminal after cell reselection occurs on the terminal. 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.

[0316] In some embodiments, cell reselection occurs when the terminal does not have an SDT requirement. Optionally, the first timer not running in the second condition means that the first timer is not started. Optionally, the first timer not running may represent that the terminal does not have an SDT requirement.

[0317] In some other embodiments, cell reselection occurs when the terminal is performing an SDT procedure. Optionally, in the SDT procedure performed by the terminal, a first timer is running, and cell reselection occurs when the first timer is running. Optionally, the first timer not running in the second condition means: the first timer is stopped. Optionally, the first timer is stopped when cell reselection occurs on the terminal. Optionally, after cell reselection occurs on the terminal, the terminal enters an RRC INACTIVE state.

[0318] In some embodiments, the second condition further includes that the terminal is unable to perform an SDT procedure in the first serving cell. Optionally, the terminal is unable to perform an SDT procedure in the first serving cell means that the terminal is unable to continue a previous SDT procedure in the first serving cell. For example, after cell reselection occurs, the terminal is unable to continue an RRC connection resumption procedure that is for SDT and was initiated in S501. Optionally, the terminal is unable to perform an SDT procedure in the first serving cell means that the terminal is unable to initiate a new SDT procedure in the first serving cell. For example, after cell reselection occurs, the terminal is unable to continue initiating a new SDT procedure for an RRC connection resumption procedure that is for SDT and was initiated in S501, or is unable to initiate a new SDT procedure for newly acquired small data. Optionally, the terminal is 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 does not support SDT includes: SDT-related configurations are not broadcast in the system information in the first serving cell. As another example, the first serving cell does not support RA-SDT and / or CG-SDT.

[0319] In some embodiments, when the terminal receives SIB1 of the current serving cell after cell reselection and the first serving cell indicated by SIB1 does not belong to the configured RNA, the terminal may determine whether the first timer is running. If the first timer is running, the terminal does not trigger the RNAU and continues to perform the SDT. Optionally, the first timer is running means that the first timer continues to run. The terminal may continue the previous SDT procedure in the serving cell. For example, after cell reselection occurs in the terminal, the first timer continues to run and the terminal may continue the RRC connection resumption procedure that is for the SDT and was initiated in S501 in the serving cell. Optionally, the first timer is running means that the first timer is started. The terminal may initiate a new RRC connection resumption procedure that is for the SDT in the serving cell. For example, after cell reselection occurs, the terminal initiates a new RRC connection resumption procedure that is for the SDT and starts the first timer. If the first timer is not running, the terminal triggers the RNAU. Optionally, the RNAU is triggered by the SIB1.

[0320] In some embodiments, when the terminal performs SDT, the second timer expires and the terminal may determine whether the first timer is running. If the first timer is running, the terminal continues to perform the SDT procedure without triggering RNAU. When the second timer expires, cell reselection occurs in the terminal, the terminal stops the first timer, and the terminal goes into the RRC INACTIVE state. If the second condition is met, the terminal may perform an RRC connection resumption procedure that is for RNAU.

[0321] In some other embodiments, if the terminal is in RRC IDLE state after cell reselection occurs, the terminal does not trigger RNAU. In some other embodiments, after cell reselection occurs, the terminal may perform an SDT procedure in the first serving cell. In this case, the terminal performs the SDT procedure without triggering RNAU. Optionally, the case in which the terminal may perform an SDT procedure in the first serving cell is opposite to the case in which the terminal cannot perform an SDT procedure in the first serving cell. For details, please refer to the above description.

[0322] Compared with the above-mentioned two examples of cases for triggering RNAU, the embodiment of the present application can be understood to add a trigger condition that the first timer is not running. Specifically, the terminal can trigger RNAU only when the terminal does not have an SDT requirement or after the executed SDT procedure is finished. If the first timer is running (e.g., the SDT procedure is executed), RNAU will not be triggered. When the SDT is executed, the network equipment can obtain the RNA where the terminal is located, and not executing RNAU not only does not affect the network equipment's acquisition of the terminal's status, but also avoids the impact on the transmission of small data in the SDT procedure, for example, avoiding an increase in transmission delay, and then avoiding unnecessary signaling overhead and power consumption increased by restarting SDT.

[0323] In a possible implementation, the terminal receives an RRC rejection message. If the second timer is not running, the terminal may set the first variable to a first value. The first variable being the first value indicates that: there is a pending RNAU. Optionally, the value of the first variable is a first value or a second value. For example, the first variable indicates whether there is a pending RNAU-Update, the first value being true, and the second value being false. For a description of the first variable and the first value, please refer to the description of the first variable and the first value in the above-mentioned implementation of performing RNAU. A specific example is shown in FIG. 14 below.

[0324] 14 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. The method includes, but is not limited to, the following steps:

[0325] S601: The terminal starts a second timer.

[0326] In some embodiments, S601 is an optional step, and S601 is similar to S401 in FIG.

[0327] S602: The terminal starts a first timer.

[0328] In some embodiments, S602 is an optional step, and S602 is similar to S501 in FIG.

[0329] In some embodiments, the execution order of S601 and S602 may be that S601 is executed before S602, or that S602 is executed before S601.

[0330] S603: The network device sends an RRCReject message to the terminal.

[0331] In some embodiments, S603 is an optional step.

[0332] In some embodiments, when the first timer runs, the terminal receives an RRCReject message and the first timer is stopped.

[0333] In some embodiments, after the terminal receives the RRCReject message, the terminal is in an RRC INACTIVE state.

[0334] In some embodiments, when the terminal initiates an RRC connection resumption procedure for SDT to the network equipment, the terminal sends an RRC request message to the network equipment, and an RRCReject message is sent by the network equipment in response to the RRC request message. The RRC request message is an RRC resumption request message, such as an RRCResumeRequest message or an RRCResumeRequest1 message.

[0335] S604: If the second timer is not running, the terminal sets a first variable to a first value.

[0336] In some embodiments, after the terminal receives the RRCReject message, the terminal enters a non-RRC connected state. Optionally, the non-RRC connected state is an RRC INACTIVE state.

[0337] In some embodiments, after the terminal receives the RRCReject message, the terminal assumes that the SDT procedure has now failed (rejected) and the terminal enters the RRC INACTIVE state. The terminal still needs to perform periodic RNAU. However, in this case, since the second timer is not running, the terminal may set the first variable to the first value.

[0338] In some embodiments, if the terminal is in an RRC INACTIVE state after receiving an RRCReject message and the second timer is not running, the terminal may set the first variable to the first value.

[0339] In some embodiments, the terminal receives an RRCReject message, and the waiting time is configured in the RRCReject message. In this case, the terminal may start a timer T302. Optionally, when the timer T302 runs, the RRC connection resumption procedure of the UE is prohibited. When the timer T302 expires, the prohibited RRC connection resumption procedure of the UE is relaxed. In this case, if the upper layer (e.g., the NAS layer, etc.) does not request the resumption of the RRC connection, the UE may restart the RRC connection resumption procedure. For example, if the first variable is set to the first value without the upper layer (e.g., the NAS layer, etc.) requesting the resumption of the RRC connection for data transmission, the UE may continue to start the RRC connection resumption procedure for RNAU.

[0340] In some embodiments, if the second timer expires when the terminal is performing an SDT procedure (e.g., before the terminal receives an RRCReject message), the terminal may determine whether the first timer is running. If the first timer is running, the terminal continues performing the SDT procedure without triggering an RNAU. After the second timer expires and the terminal receives an RRCReject message, the terminal stops the first timer and enters an RRC INACTIVE state. If the second timer is not running, the terminal may set the first variable to a first value. Optionally, the second timer is not running means that the second timer is not running after it expires.

[0341] In some embodiments, after the terminal receives the RRCReject message, if the terminal is in an RRC IDLE state, the terminal does not trigger RNAU or set the first variable to the first value.

[0342] The message received by the terminal is not limited to the RRC reject message shown in Figure 14. In some other embodiments, the RRCReject message may alternatively be an RRCConnectionReject message or other RRC messages having the same functionality but not standardized in 3GPP.

[0343] This is not limited to the example shown in FIG. 14. In some other embodiments, if the second timer is not running after the terminal receives the RRC rejection message, the terminal may directly perform the RRC connection resumption procedure for the RNAU. A specific example is similar to that in FIG. 14. The difference is that "set the first variable to a first value" in FIG. 14 is replaced with "perform the RRC connection resumption procedure for the RNAU". For example, the RRC layer of the terminal performs the RRC connection resumption procedure for the RNAU. Optionally, the terminal receives an RRCReject message, and no waiting time is configured in the RRCReject message. In this case, the terminal performs the RRC connection resumption procedure for the RNAU. For example, the RRC layer of the terminal directly performs the RRC connection resumption procedure for the RNAU.

[0344] In some other embodiments, the terminal may initially set the first variable to the first value, and then the terminal performs an RRC connection resumption procedure for RNAU. For example, the RRC layer of the terminal directly performs an RRC connection resumption procedure for RNAU.

[0345] In some other embodiments, after the terminal receives the RRC rejection message, if the second timer is not running, the terminal may start a third timer. When the third timer expires, if the first timer is not running, the terminal performs an RRC connection resumption procedure for RNAU. A specific example is similar to that in FIG. 14, with the difference being that "setting a first variable to a first value" in FIG. 14 is replaced by "starting a third timer". Optionally, the method further includes: when the third timer expires, if the first timer is not running, the terminal performs an RRC connection resumption procedure for RNAU.

[0346] Optionally, the third timer is the same as the second timer, e.g., the duration of the third timer is equal to the duration of the second timer, e.g., the third timer is T380.

[0347] Optionally, the third timer is different from the second timer. For example, the duration of the third timer is not equal to the duration of the second timer. For example, the duration of the third timer is less than the duration of the second timer. For example, the unit of the duration of the third timer is milliseconds or seconds.

[0348] Optionally, during the execution of the third timer, the terminal may wait whether there is a data transmission requirement on the NAS layer, for example, whether the NAS triggers the RRC layer to start a connection resumption procedure. If there is a data transmission requirement on the NAS layer and the NAS layer triggers the RRC layer to start a connection resumption procedure, the terminal starts an RRC connection resumption procedure for data transmission and does not perform an RRC connection resumption procedure for RNAU. The RRC connection resumption procedure for data transmission includes an RRC connection resumption procedure for SDT and an RRC connection resumption procedure for non-SDT.

[0349] In some embodiments, the following:

[0350] 1> If an RRCReject is received in response to an RRCResumeRequest or RRCResumeRequest1,

[0351] 2> Resume is triggered due to an SDT procedure, and

[0352] 2> If the T380 expires,

[0353] 3> Set the variable pendingRNA-Update to true.

[0354] In some embodiments, if the terminal receives an RRCReject message in response to the RRCResumeRequest message or the RRCResumeRequest1 message, and the resuming step is triggered based on the SDT procedure and the second timer expires, the terminal may set a first variable to a first value, and the terminal may request the resuming step by sending an RRCResumeRequest message or the RRCResumeRequest1 message. Optionally, the resuming step is an RRC Connection Resumption procedure that is for SDT.

[0355] In a possible implementation, when the first timer expires and the second timer is not running, the terminal may set the first variable to a first value. The first variable being the first value indicates that there is a 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-mentioned implementation of performing RNAU. A specific example is shown in Figure 15 below.

[0356] 15 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. The method includes, but is not limited to, the following steps:

[0357] S701: The terminal starts a second timer.

[0358] In some embodiments, S701 is an optional step, and S701 is similar to S401 in FIG.

[0359] S702: The terminal starts a first timer.

[0360] In some embodiments, S702 is an optional step, and S702 is similar to S501 in FIG.

[0361] In some embodiments, the execution order of S701 and S702 may be such that S701 is executed before S702, or S702 is executed before S701.

[0362] S703: When the first timer expires, if the second timer is not running, the terminal sets a first variable to a first value.

[0363] In some embodiments, after the first timer expires, the terminal is in a non-RRC connected state. Optionally, the non-RRC connected state is an RRC INACTIVE state. In some embodiments, when the terminal is in the RRC INACTIVE state, the terminal initiates an RRC connection resumption procedure for SDT to the network device and starts the first timer. After the first timer expires, the terminal is still in the RRC INACTIVE state.

[0364] In some embodiments, after the first timer expires, the terminal goes into the RRC INACTIVE state. The terminal still needs to perform periodic RNAU. However, in this case, since the second timer is not running, the terminal may set the first variable to the first value.

[0365] In some embodiments, if the terminal enters an 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.

[0366] In some embodiments, if the second timer expires when the terminal is performing the SDT procedure (e.g., before the first timer expires), the terminal may determine whether the first timer is running. If the first timer is running, the terminal continues performing the SDT procedure without triggering RNAU. If the first timer expires after the second timer expires, the terminal enters the RRC INACTIVE state. If the second timer is not running, the terminal may set the first variable to a first value. Optionally, the second timer is not running means the following: the second timer is not running after the second timer expires.

[0367] In some other embodiments, if the terminal is in the RRC IDLE state after the first timer expires, the terminal does not set the first variable to the first value without triggering an RNAU.

[0368] This is not limited to the example shown in Figure 15. In some other embodiments, when the first timer expires, if the second timer is not running, the terminal may directly perform an RRC connection resumption procedure for RNAU. A specific example is similar to that in Figure 15. The difference is that "setting a first variable to a first value" in Figure 15 is replaced with "performing an RRC connection resumption procedure for RNAU". For example, the RRC layer of the terminal performs an RRC connection resumption procedure for RNAU.

[0369] In some other embodiments, the terminal may initially set the first variable to the first value, and then the terminal performs an RRC connection resumption procedure for RNAU. For example, the RRC layer of the terminal directly performs an RRC connection resumption procedure for RNAU.

[0370] In some other embodiments, when the first timer expires, if the second timer is not running, the terminal may start a third timer. When the third timer expires, if the first timer is not running, the terminal performs an RRC connection resumption procedure for RNAU. A specific example is similar to that in FIG. 15, with the difference being that "setting a first variable to a first value" in FIG. 15 is replaced with "starting a third timer". Optionally, the method further includes: when the third timer expires, if the first timer is not running, the terminal performs an RRC connection resumption procedure for RNAU.

[0371] Optionally, the third timer is the same as the second timer, e.g., the duration of the third timer is equal to the duration of the second timer, e.g., the third timer is T380.

[0372] Optionally, the third timer is different from the second timer. For example, the duration of the third timer is not equal to the duration of the second timer. For example, the duration of the third timer is less than the duration of the second timer. For example, the unit of the duration of the third timer is milliseconds or seconds.

[0373] Optionally, during the execution of the third timer, the terminal may wait whether there is a data transmission requirement on the NAS layer, for example, whether the NAS triggers the RRC layer to start a connection resumption procedure. If there is a data transmission requirement on the NAS layer and the NAS layer triggers the RRC layer to start a connection resumption procedure, the terminal starts an RRC connection resumption procedure for data transmission and does not perform an RRC connection resumption procedure for RNAU. The RRC connection resumption procedure for data transmission includes an RRC connection resumption procedure for SDT and an RRC connection resumption procedure for non-SDT.

[0374] In a possible implementation, 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, the terminal may set the first variable to a first value. The first value of the first variable indicates the following: that is, there is a 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-mentioned implementation of performing RNAU. A specific example is shown in Figure 16 below.

[0375] 16 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. The method includes, but is not limited to, the following steps:

[0376] S801: The terminal starts a second timer.

[0377] In some embodiments, S801 is an optional step, and S801 is similar to S401 in FIG.

[0378] S802: The terminal starts a first timer.

[0379] In some embodiments, S802 is an optional step, and S802 is similar to S501 in FIG.

[0380] In some embodiments, the execution order of S801 and S802 may be that S801 is executed before S802, or that S802 is executed before S801.

[0381] S803: Cell reselection occurs on the terminal.

[0382] In some embodiments, S803 is an optional step.

[0383] In some embodiments, cell reselection occurs when the terminal and the network equipment are performing an SDT procedure. In some embodiments, cell reselection occurs on the terminal when the first timer is running, and the terminal stops the first timer.

[0384] In some embodiments, a cell reselection occurs in the terminal, and the terminal switches from a third cell to a fourth cell. In other words, the serving cell obtained through the cell reselection occurring in the terminal is the fourth cell, hereafter referred to as the second serving cell. In some embodiments, the second serving cell of the terminal belongs to a configured RNA, and the RNA is configured by the network equipment for the terminal before the cell reselection occurs on the terminal.

[0385] In some embodiments, after cell reselection occurs, the terminal receives SIB1 of a current serving cell, and determines a second serving cell based on SIB1, where SIB1 indicates the second serving cell. In some embodiments, the terminal determines that the second serving cell belongs to a configured RNA based on SIB1, where the RNA is configured by a network device for the terminal before cell reselection occurs on the terminal. A specific example is similar to S502 in FIG. 11, and details will not be described again.

[0386] In some embodiments, after cell reselection occurs on the terminal, the terminal is in a non-RRC connected state. Optionally, the non-RRC connected state is an RRC INACTIVE state.

[0387] 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 a first value.

[0388] In some embodiments, after cell reselection occurs on the terminal, the terminal is in a non-RRC connected state. Optionally, the non-RRC connected state is an RRC INACTIVE state. In some embodiments, when the terminal is in the RRC INACTIVE state, the terminal initiates an RRC connection resumption procedure for SDT to the network equipment and starts a first timer. Cell reselection occurs when the first timer is running and the terminal is still in the RRC INACTIVE state.

[0389] In some embodiments, after a cell reselection occurs on the terminal, if the terminal is in an RRC INACTIVE state, the second serving cell belongs to a configured RNA, and the second timer is not running, the terminal may set the first variable to the first value.

[0390] In some embodiments, when the terminal is in the RRC INACTIVE state, if the second serving cell belongs to the configured RNA and the terminal cannot perform the SDT procedure in the second serving cell without the second timer running, the terminal may set the first variable to the first value. Optionally, the terminal cannot 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 cell reselection occurs, the terminal cannot continue the RRC connection resumption procedure that is for SDT and was initiated in S802. Optionally, the terminal cannot perform the SDT procedure in the second serving cell means that the terminal cannot start a new SDT procedure in the second serving cell. For example, after cell reselection occurs, the terminal cannot continue the initiation of a new SDT procedure that is for SDT and is for the RRC connection resumption procedure that was initiated in S802, or cannot perform 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 that the SDT-related configuration is not broadcast in the system information in the second serving cell. As another example, the second serving cell does not support RA-SDT and / or CG-SDT.

[0391] In some embodiments, after cell reselection occurs on the terminal, the terminal is in an RRC INACTIVE state. The terminal still needs to perform periodic RNAU. However, in this case, since the second timer is not running, the terminal may set the first variable to the first value.

[0392] In some embodiments, if the second timer expires when the terminal is performing an SDT procedure (e.g., before cell reselection occurs), the terminal may determine whether the first timer is running. If the first timer is running, the terminal continues performing the SDT procedure without triggering the RNAU. Optionally, the first timer running means that the first timer continues to run, and the terminal may continue the previous SDT procedure in the second serving cell. Optionally, the first timer running means that the first timer is started, and the terminal may initiate a new RRC connection resumption procedure that is for SDT in the second serving cell. After the second timer expires, cell reselection occurs on the terminal, the terminal stops the first timer, and the terminal goes into the RRC INACTIVE state. If the second timer is not running, the terminal may set the first variable to a first value. Optionally, the second timer not running means that the second timer is not running after it expires.

[0393] In some other embodiments, after cell reselection occurred on the terminal, if the terminal is in RRC IDLE state, the terminal does not trigger RNAU and does not set the first variable to the first value. In some other embodiments, after cell reselection occurred on the terminal, the terminal may perform an SDT procedure in the second serving cell and the terminal does not trigger RNAU and does not set the first variable to the first value.

[0394] This is not limited to the example shown in Figure 16. In some other embodiments, 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, the terminal may directly perform the RRC connection resumption procedure for RNAU. A specific example is similar to that in Figure 16. The difference is that "setting the first variable to the first value" in Figure 16 is replaced with "performing the RRC connection resumption procedure for RNAU". For example, the RRC layer of the terminal performs the RRC connection resumption procedure for RNAU.

[0395] In some other embodiments, the terminal may initially set the first variable to the first value, and then the terminal performs an RRC connection resumption procedure for the RNAU. For example, the RRC layer of the terminal directly performs an RRC connection resumption procedure for the RNAU.

[0396] In some other embodiments, 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, the terminal starts a third timer. A specific example is similar to that in Fig. 16, with the difference being that "setting the first variable to a first value" in Fig. 16 is replaced by "starting a third timer". Optionally, the method further includes: when the third timer expires, if the first timer is not running, the terminal performs an RRC connection resumption procedure that is for RNAU.

[0397] Optionally, the third timer is the same as the second timer, e.g., the duration of the third timer is equal to the duration of the second timer, e.g., the third timer is T380.

[0398] Optionally, the third timer is different from the second timer. For example, the duration of the third timer is not equal to the duration of the second timer. For example, the duration of the third timer is less than the duration of the second timer. For example, the unit of the duration of the third timer is milliseconds or seconds.

[0399] Optionally, during the execution of the third timer, the terminal may wait whether there is a data transmission requirement on the NAS layer, for example, whether the NAS triggers the RRC layer to start a connection resumption procedure. If there is a data transmission requirement on the NAS layer and the NAS layer triggers the RRC layer to start a connection resumption procedure, the terminal starts an RRC connection resumption procedure for data transmission and does not perform an RRC connection resumption procedure for RNAU. The RRC connection resumption procedure for data transmission includes an RRC connection resumption procedure for SDT and an RRC connection resumption procedure for non-SDT.

[0400] In some embodiments, the following:

[0401] 1> When cell reselection occurs while T319, T302, or T3XX is operating,

[0402] 2> If the T380 expires during the SDT procedure or has expired during the SDT procedure,

[0403] 3> Set the variable pendingRNA-Update to true.

[0404] In some embodiments, if a cell reselection occurs on the terminal when timer T319, timer T302, or the first timer T3XX is running, and if the second timer T380 expires or has expired in an SDT procedure, the terminal may set the variable pendingRNA-Update to true.

[0405] In a possible implementation, when the terminal's integrity check fails and the second timer is not running, the terminal may set the first variable to a first value. The first variable being the first value indicates that there is a 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-mentioned embodiment of performing RNAU. A specific example is shown in FIG. 17 below.

[0406] 17 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. The method includes, but is not limited to, the following steps:

[0407] S901: The terminal starts a second timer.

[0408] In some embodiments, S901 is an optional step, and S901 is similar to S401 in FIG.

[0409] S902: The terminal starts a first timer.

[0410] In some embodiments, S902 is an optional step, and S902 is similar to S501 in FIG.

[0411] In some embodiments, the execution order of S901 and S902 may be such that S901 is executed before S902, or S902 is executed before S901.

[0412] S903: When the integrity check of the terminal fails, if the second timer is not running, the terminal sets a first variable to a first value.

[0413] In some embodiments, when the first timer is running, the terminal's integrity check fails. In some embodiments, the terminal's integrity check fails as follows: the RRC layer of the terminal receives an integrity check failure indicated by the lowest layer of the RRC layer, for example the PDCP layer.

[0414] In some embodiments, after the terminal integrity check fails, the terminal goes into an RRC INACTIVE state. In some embodiments, when the terminal is in the RRC INACTIVE state, the terminal initiates an RRC connection resumption procedure for SDT with the network device and starts a first timer. If the first timer is running, after the terminal integrity check fails, the terminal is still in the RRC INACTIVE state.

[0415] In some embodiments, after the terminal integrity check fails, the terminal goes into the RRC INACTIVE state. The terminal still needs to perform periodic RNAU. However, in this case, since the second timer is not running, the terminal may set the first variable to the first value.

[0416] In some embodiments, if the second timer expires when the terminal is performing the SDT procedure (e.g., before the terminal's integrity check fails), the terminal may determine whether the first timer is running. If the first timer is running, the terminal continues performing the SDT procedure without triggering RNAU. If the terminal's integrity check fails after the second timer expires, the terminal goes into the RRC INACTIVE state. If the second timer is not running, the terminal may set the first variable to a first value. Optionally, the second timer is not running means the following: the second timer is not running after the second timer expires.

[0417] In some embodiments, after the terminal integrity check fails, if the terminal is in RRC IDLE state, the terminal does not trigger RNAU or set the first variable to the first value.

[0418] This is not limited to the example shown in Figure 17. In some other embodiments, if the second timer is not running when the terminal integrity check fails, the terminal may directly perform an RRC connection resumption procedure for RNAU. A specific example is similar to that in Figure 17. The difference is that "setting a first variable to a first value" in Figure 17 is replaced with "performing an RRC connection resumption procedure for RNAU". For example, the RRC layer of the terminal performs an RRC connection resumption procedure for RNAU.

[0419] In some other embodiments, the terminal may initially set the first variable to the first value, and then the terminal performs an RRC connection resumption procedure for RNAU. For example, the RRC layer of the terminal directly performs an RRC connection resumption procedure for RNAU.

[0420] In some other embodiments, when the terminal's integrity check fails, if the second timer is not running, the terminal may start a third timer. When the third timer expires, if the first timer is not running, the terminal performs an RRC connection resumption procedure for RNAU. A specific example is similar to that in FIG. 17, with the difference being that "setting a first variable to a first value" in FIG. 17 is replaced by "starting a third timer". Optionally, the method further includes: That is, when the third timer expires, if the first timer is not running, the terminal performs an RRC connection resumption procedure for RNAU.

[0421] Optionally, the third timer is the same as the second timer, e.g., the duration of the third timer is equal to the duration of the second timer, e.g., the third timer is T380.

[0422] Optionally, the third timer is different from the second timer. For example, the duration of the third timer is not equal to the duration of the second timer. For example, the duration of the third timer is less than the duration of the second timer. For example, the unit of the duration of the third timer is milliseconds or seconds.

[0423] Optionally, during the execution of the third timer, the terminal may wait whether there is a data transmission requirement on the NAS layer, for example, whether the NAS triggers the RRC layer to start a connection resumption procedure, etc. If there is a data transmission requirement on the NAS layer and the NAS layer triggers the RRC layer to start a connection resumption procedure, the terminal starts an RRC connection resumption procedure for data transmission and does not perform an RRC connection resumption procedure for RNAU. The RRC connection resumption procedure for data transmission includes an RRC connection resumption procedure for SDT and an RRC connection resumption procedure for non-SDT.

[0424] In the present application, it can be understood that when the SDT procedure is performed, the RNAU is not triggered. When the SDT procedure is performed, the network equipment can obtain the RNA where the terminal is located, and not performing the RNAU not only does not affect the network equipment's acquisition of the terminal's status, but also can avoid the impact on the transmission of small data in the SDT procedure.

[0425] In addition, in the case where the SDT is terminated abnormally (e.g., when a fourth RRC response message is received, when cell reselection occurs, when the first timer expires, or when the terminal integrity check fails), if the second timer is not running (e.g., the second timer is not running after the second timer expires), the terminal may set the first variable to the first value, so that the UE can continue to trigger RNAU periodically thereafter, and the normal execution of RNAU is not affected.

[0426] In a possible implementation, if the first variable is set to the first value in the SDT procedure, the terminal may perform an RRC connection resumption procedure for RNAU. In some embodiments, if the first variable is set to the first value in the SDT procedure and the higher layer (e.g., NAS layer, etc.) does not request the resumption of the RRC connection, the terminal performs an RRC connection resumption procedure for RNAU. In some embodiments, if the prohibition of the access category 2 or 8 of the terminal is relaxed and the first variable is set to the first value without the higher layer (e.g., NAS layer, etc.) requesting the resumption of the RRC connection, the terminal performs an RRC connection resumption procedure for RNAU. In some embodiments, if the prohibition of the access category of the terminal is relaxed in the SDT procedure and the first variable is set to the first value without the higher layer (e.g., NAS layer, etc.) requesting the resumption of the RRC connection, the terminal performs an RRC connection resumption procedure for RNAU. In some embodiments, if the access prohibition is relaxed and a higher layer (such as the NAS layer) does not request the RRC layer to resume the RRC connection, and if the first variable is a first value, the terminal may perform an RRC connection resumption procedure that is for RNAU.

[0427] FIG. 18 shows another example of a sequence diagram.

[0428] As shown in FIG. 18, the horizontal axis is the time axis (t). 3 At a fourth time point t 4 At a fifth time point t 5 At t, the second timer expires. 3 <t 4 <t 5 <t 6The second timer runs between the third time point and the fifth time point, the first timer runs between the fourth time point and the sixth time point, and the terminal performs the SDT procedure between the fourth time point and the sixth time point. When the terminal performs the SDT procedure at the fifth time point, the second timer expires and the terminal does not trigger RNAU. In other words, if the second timer expires and the first timer is running, the terminal does not trigger RNAU.

[0429] In some embodiments, at the sixth time point, cell reselection occurs on the terminal, the first timer is stopped, and the terminal enters an RRC INACTIVE state. If the terminal's serving cell obtained through cell reselection does not belong to the configured RNA and the terminal cannot perform an SDT procedure in the serving cell, the terminal may trigger an RNAU. Optionally, the step of triggering an RNAU is a step of performing an RRC connection resumption procedure that is for an RNAU. For details, please refer to the description in FIG. 13.

[0430] In some other embodiments, at a sixth time point, the terminal receives a fourth RRC response message, the first timer is stopped, and the terminal enters an RRC INACTIVE state. If the second timer does not run, the terminal may trigger an RNAU. Optionally, the step of triggering an RNAU may be a step of setting a first variable to a first value. For details, see the description in FIG. 14.

[0431] In some other embodiments, at the sixth time point, the first timer expires and the terminal goes into the RRC INACTIVE state. If the second timer is not running, the terminal may trigger the RNAU. Optionally, the step of triggering the RNAU may be a step of setting the first variable to the first value. For details, see the description in FIG. 15.

[0432] In some other embodiments, at the sixth time point, cell reselection occurs on the terminal, the first timer is stopped, and the terminal enters the RRC INACTIVE state. If the terminal's serving cell obtained through cell reselection belongs to the configured RNA, the terminal may not be able to perform the SDT procedure in the serving cell, in which case the second timer does not run, and the terminal may trigger RNAU. Optionally, the step of triggering RNAU may be a step of setting the first variable to a first value. For details, see the description in FIG. 16.

[0433] In some other embodiments, at the sixth time point, the terminal's integrity check fails, the first timer stops, and the terminal goes into the RRC INACTIVE state. If the second timer is not running, the terminal may trigger an RNAU. Optionally, the step of triggering an RNAU may be a step of setting a first variable to a first value. For details, see the description in FIG. 17.

[0434] In a possible implementation, when performing the SDT procedure, the terminal may stop the second timer. A specific example is shown in Figure 19 below.

[0435] 19 is a schematic flow chart illustrating another transmission control method according to an embodiment of the present application. The method includes, but is not limited to, the following steps:

[0436] S1001: A terminal sends an RRC request message to a network device.

[0437] In some embodiments, S1001 is an optional step.

[0438] In some embodiments, if the terminal has an SDT requirement, the terminal may initiate an RRC connection resumption procedure that is for the SDT. The RRC connection resumption procedure may include: the terminal sending an RRC request message to a network device based on the SDT.

[0439] In some embodiments, if the terminal has an SDT requirement, the terminal may initiate an RRC connection resumption procedure that is for 4-step SDT. For the procedure, refer to the procedures shown in Figures 5 and 6. The RRC request message sent by the terminal in the RRC connection resumption procedure is sent based on the 4-step SDT, and the RRC request message may be included in msg3.

[0440] In some embodiments, if the terminal has an SDT requirement, the terminal may initiate an RRC connection resumption procedure that is for 2-step SDT. For the procedure, refer to the procedures shown in Figures 7 and 8. The RRC request message sent by the terminal in the RRC connection resumption procedure may be sent based on the 2-step SDT, and the RRC request message may be included in msgA.

[0441] In some embodiments, if the terminal has an SDT requirement, the terminal may initiate an RRC connection resumption procedure that is for CG-SDT. For the procedure, refer to the procedures shown in Figures 9 and 10. The RRC request message sent by the terminal in the RRC connection resumption procedure is sent based on the CG-SDT.

[0442] In some embodiments, when sending the RRC request message to the network device, the terminal also transmits uplink small data. For specific examples, see the procedures illustrated in Figures 5, 7, and 9.

[0443] S1002: The network device sends a first response message to the terminal.

[0444] In some embodiments, S1002 is an optional step.

[0445] In some embodiments, after receiving the RRC request message sent by the terminal, the network device may send a first response message to the terminal. In some embodiments, after receiving the RRC request message and uplink small data sent by the terminal, the network device may send a first response message to the terminal.

[0446] In some embodiments, the terminal may initiate RA-SDT, and the network device may receive an RRC request message sent by the terminal based on the RA-SDT and send a first response message to the terminal. Optionally, the first response message may indicate that contention resolution is successful. Optionally, the first response message may indicate that the random access procedure is completed successfully. Optionally, the terminal receives the first response message and determines that contention resolution is successful. Optionally, the terminal receives the first response message and determines that the random access procedure is completed successfully. Optionally, the first response message is a contention resolution message shown in Figures 5 to 8.

[0447] In some embodiments, the terminal may initiate a CG-SDT, and the network device may receive an RRC request message sent by the terminal based on the CG-SDT and send a first response message to the terminal. Optionally, the first response message may be specific to the RRC request message and / or the uplink small data sent in S1001. Optionally, the first response message may indicate that the RRC request message has been successfully transmitted. Optionally, the first response message may indicate that the uplink small data has been successfully transmitted. Optionally, the first response message is a feedback response message shown in FIG. 9 and FIG. 10. Optionally, the first response message may be a downlink control information (DCI) for scheduling a retransmission. Optionally, the first response message may be a DCI for scheduling a new transmission.

[0448] S1003: The lower layer of the terminal indicates the first information to the upper layer.

[0449] In some embodiments, S1003 is an optional step.

[0450] Specifically, the terminal may include multiple layers. For specific examples, see the layers included in the user plane protocol stack or the control plane protocol stack shown in FIG. 2 and FIG. 3. The lowest layer and the upper layer in S1003 may be understood to be relative concepts. In some embodiments, the lowest layer of the terminal in S1003 is a first layer, and the first layer is a layer in the user plane protocol stack or the control plane protocol stack. In some embodiments, the first layer is a layer that receives the first response message sent by the network device. In some embodiments, the upper layer in S1003 is a second layer, and the second layer is a layer above the first layer.

[0451] For example, the first layer is a MAC layer and the second layer is an RRC layer.

[0452] For example, the first layer is the physical layer and the second layer is the MAC layer.

[0453] For example, the first layer is a physical layer and the second layer is an RRC layer.

[0454] S1004: The terminal stops the second timer.

[0455] In some embodiments, a third layer of the terminal receives the first information indicated by a lower layer of the third layer and stops the second timer. Optionally, the third layer is an RRC layer. Optionally, the lower layer of the third layer is a MAC layer. Optionally, the lower layer of the third layer is a physical layer.

[0456] In some embodiments, in the RA-SDT procedure, the MAC layer of the terminal receives a first response message sent by the network device, and the MAC layer indicates first information to an RRC layer above the MAC layer. Optionally, the first information indicates that contention resolution is successful, and optionally, the first indication information indicates that the random access procedure is successfully completed. The RRC layer receives the first information indicated by the MAC layer and stops a second timer. Optionally, in S1003, the lower layer is a MAC layer, and the upper layer is an RRC layer, and in S1004, the second timer is stopped in the RRC layer.

[0457] In some embodiments, in the CG-SDT procedure, a MAC layer of the terminal receives a first response message sent by the network device, the MAC layer indicates first information to an RRC layer above the MAC layer, the first information indicates that the RRC request message and / or the uplink small data has been successfully transmitted, and the RRC layer receives the first information indicated by the MAC layer and stops the second timer. Optionally, in S1003, the lower layer is a MAC layer and the upper layer is an RRC layer, and in S1004, the second timer is stopped in the RRC layer.

[0458] In some embodiments, in the CG-SDT procedure, a physical layer of the terminal receives a first response message sent by the network device, the physical layer indicates first information to an RRC layer above the physical layer, the first information indicates that the RRC request message and / or the uplink small data has been successfully transmitted, the RRC layer receives the first information indicated by the physical layer and stops the second timer. Optionally, in S1003, the lower layer is a physical layer and the upper layer is an RRC layer, and in S1004, the second timer is stopped in the RRC layer.

[0459] In some embodiments, in the CG-SDT procedure, the physical layer of the terminal receives a first response message sent by the network device, the physical layer indicates second information to a MAC layer above the physical layer, the second information indicating that the RRC request message and / or the uplink small data has been successfully transmitted. The MAC layer receives the second information indicated by the physical layer and indicates first information to an RRC layer above the MAC layer, the first information indicating that the RRC request message and / or the uplink small data has been successfully transmitted, the RRC layer receives the first information indicated by the MAC layer and stops the second timer. Optionally, in S1003, the lowest layer is the MAC layer and the upper layer is the RRC layer, and in S1004, the second timer is stopped in the RRC layer.

[0460] In some embodiments, the second timer is in an ON state before the terminal stops the second timer, e.g., before starting an RRC connection resumption procedure for SDT (e.g., S1001, etc.), the terminal starts the second timer.

[0461] In some embodiments, after stopping the second timer, the terminal may now perform a subsequent transmission based on the SDT procedure. For details, see the description of the subsequent transmission in Figures 5 to 10. The second timer is stopped and does not expire. Therefore, the RNAU is not triggered and the transmission of small data in the SDT procedure is not affected.

[0462] In some embodiments, after stopping the second timer, the terminal may receive an RRC response message sent by the network equipment. For details, see the above description of the RRC response message in Figures 5 to 10. In some embodiments, after stopping the second timer, the terminal receives a first RRC response message sent by the network equipment, such as an RRCRelease message, an RRCRelease message with suspend configuration, or another RRC message having the same function but not standardized in 3GPP, and the terminal may start the second timer.

[0463] It can be understood that the step of starting the second timer in the above embodiment includes multiple cases. Two cases are given as examples below.

[0464] Case 1: When performing SDT, the terminal receives a first RRC response message, stops the first timer, and starts the second timer. For example, first, when the terminal has an SDT request, the terminal starts an RRC connection resumption procedure for SDT and starts the first timer. Then, when the second timer expires, if the first timer is in an active state, the terminal continues to perform SDT without triggering RNAU. Finally, after the terminal receives the first RRC response message, the terminal considers this SDT to be successful, stops the first timer, and maintains a non-RRC connected state. Furthermore, after receiving the first RRC response message, the terminal starts the second timer, so that RNAU may continue to be periodically triggered thereafter.

[0465] Case 2: When performing SDT, the terminal receives a fifth RRC response message and stops the first timer. After that, when receiving the first RRC response message, the terminal then starts a second timer, and the fifth RRC response message is, for example, an RRCResume message, an RRCSetup message, or another RRC message having the same function but not standardized in 3GPP. For example, if the terminal has an SDT requirement at first, the terminal starts an RRC connection resumption procedure for SDT and starts the first timer. Then, if the second timer expires but the first timer is in an active state, the terminal continues to perform SDT without triggering RNAU. Then, after the terminal receives the fifth RRC response message, the terminal may consider this SDT to be successful, stop the first timer, and transition from a non-RRC connected state to an RRC connected state. The terminal then receives a first RRC response message, transitions from an RRC CONNECTED state to a non-RRC CONNECTED state, and starts a second timer, which may cause the RNAU to continue to be triggered periodically thereafter.

[0466] In a possible implementation, after the terminal receives an RRC rejection message, if the second timer is not running, the terminal may set the first variable to a first value. A specific example is similar to that in Fig. 14. The difference is that "the second timer expires" in Fig. 14 should be replaced by "the second timer stops". Please refer to Fig. 19 above for an explanation of the stop of the second timer.

[0467] In a possible implementation, after the terminal receives the RRC rejection message, if the second timer is not running, the terminal may directly perform an RRC connection resumption procedure for RNAU. A specific example is similar to that in FIG. 14. The difference is that S604 may be modified as follows: if the second timer is not running, perform an RRC connection resumption procedure for RNAU, and "the second timer expires" in FIG. 14 needs to be replaced with "the second timer stops". Please refer to FIG. 19 above for an explanation of the stop of the second timer.

[0468] In a possible implementation, after the terminal receives an RRC rejection message, if the second timer is not running, the terminal may start a third timer. If the first timer is not running when the third timer expires, the terminal performs an RRC connection resumption procedure for RNAU. A specific example is similar to that in FIG. 14. The difference is that S604 may be modified as follows: if the second timer is not running, start a third timer. After S604, the method further includes: That is, if the first timer is not running when the third timer expires, the terminal performs an RRC connection resumption procedure for RNAU, and "the second timer expires" in FIG. 14 should be replaced by "the second timer stops". For an explanation of the stop of the second timer, please refer to FIG. 19 above.

[0469] In a possible implementation, when the first timer expires and the second timer is not running, the terminal may set the first variable to a first value. A specific example is similar to that in Fig. 15. The difference is that "the second timer expires" in Fig. 15 should be replaced by "the second timer stops". For the stop of the second timer, please refer to Fig. 19 above.

[0470] In a possible implementation, if the second timer is not running when the first timer expires, the terminal may directly perform an RRC connection resumption procedure for RNAU. A specific example is similar to that in FIG. 15. The difference is that S703 may be modified as follows: if the second timer is not running when the first timer expires, an RRC connection resumption procedure for RNAU is performed, and "the second timer expires" in FIG. 15 needs to be replaced with "the second timer stops". Please refer to FIG. 19 above for an explanation of the stop of the second timer.

[0471] In a possible implementation, when the first timer expires, if the second timer is not running, the terminal may start a third timer. When the third timer expires, if the first timer is not running, the terminal performs an RRC connection resumption procedure for RNAU. A specific example is similar to that in FIG. 15. The difference is that S703 may be modified as follows: when the first timer expires, if the second timer is not running, start a third timer. After S703, the method further includes: when the third timer expires, if the first timer is not running, the terminal performs an RRC connection resumption procedure for RNAU, and "the second timer expires" in FIG. 15 needs to be replaced with "the second timer stops". For an explanation of the stop of the second timer, please refer to FIG. 19 above.

[0472] In a possible implementation, 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, the terminal may set the first variable to the first value. A specific example is similar to that in FIG. 16. The difference is that "the second timer expires" in FIG. 16 needs to be replaced by "the second timer stops". Please refer to FIG. 19 above for an explanation of the stopping of the second timer.

[0473] In a possible implementation, 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, the terminal may directly perform the RRC connection resumption procedure for RNAU. A specific example is similar to that in FIG. 15. The difference is that S804 may be modified as follows: if the second serving cell belongs to the configured RNA and the second timer is not running, the RRC connection resumption procedure for RNAU is performed, and "the second timer expires" in FIG. 16 needs to be replaced with "the second timer stops". For the stop of the second timer, please refer to FIG. 19 above.

[0474] In a possible implementation, 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, the terminal starts the third timer. A specific example is similar to that in FIG. 16. The difference is that S804 can be changed as follows: if the second serving cell belongs to the configured RNA and the second timer is not running, the terminal starts the third timer. After S804, the method further includes: if the first timer is not running when the third timer expires, the terminal performs an RRC connection resumption procedure for RNAU, and "the second timer expires" in FIG. 16 needs to be replaced with "the second timer stops". Please refer to FIG. 19 above for an explanation of the stop of the second timer.

[0475] In a possible implementation, when the terminal's integrity check fails, if the second timer is not running, the terminal may set the first variable to a first value. A specific example is similar to that in FIG. 17. The difference is that "the second timer expires" in FIG. 17 should be replaced with "the second timer stops." For an explanation of the stopping of the second timer, please refer to FIG. 19 above.

[0476] In a possible implementation, when the terminal integrity check fails, if the second timer is not running, the terminal may directly perform an RRC connection resumption procedure for RNAU. A specific example is similar to that in FIG. 17. The difference is that S903 may be modified as follows: if the integrity check fails and the second timer is not running, perform an RRC connection resumption procedure for RNAU, and "the second timer expires" in FIG. 17 needs to be replaced by "the second timer stops". Please refer to FIG. 19 above for an explanation of the stop of the second timer.

[0477] In a possible implementation, when the terminal's integrity check fails, if the second timer is not running, the terminal may start a third timer. A specific example is similar to that in FIG. 17. The difference is that S903 may be changed as follows: if the integrity check fails and the second timer is not running, start the third timer. After S903, the method further includes: if the first timer is not running when the third timer expires, the terminal performs an RRC connection resumption procedure for RNAU, and "the second timer expires" in FIG. 17 needs to be replaced with "the second timer stops". For the stop of the second timer, please refer to FIG. 19 described above.

[0478] In a possible implementation, after the terminal sets the first variable to a first value in an SDT procedure, if the access prohibition is relaxed and the non-access NAS layer does not request the RRC layer to perform RRC connection resumption, and if the first variable is the first value, the terminal may perform an RRC connection resumption procedure for RNAU.

[0479] It may be understood that the SDT procedure in the present application (e.g., the SDT procedure shown in FIG. 5 to FIG. 10) may include the above-mentioned RRC connection resume procedure for SDT. Optionally, the resumeCause IE in the transmitted RRC request message is mo-data. The RNAU in the present application (e.g., the above-mentioned example in the implementation of performing RNAU) may include the above-mentioned RRC connection resume procedure for RNAU. Optionally, the resumeCause IE in the transmitted RRC request message is rna-Update.

[0480] This is not limited to the above listed cases. In some other embodiments, when the terminal is in the RRC IDLE state, the RNAU may need to be performed. The specific implementation is similar to that of the UE in the RRC INACTIVE state, but the description may be different. For example, the RRC connection resumption procedure for the RNAU may be replaced by the RRC connection setup procedure for the RNAU.

[0481] The message received by the terminal is not limited to SIB1 in the above example. In some other embodiments, the terminal may receive another message and determine whether the serving cell belongs to the configured RNA based on the message. For example, the terminal reads a cell ID from the message and determines whether the read cell ID belongs to the cell ID included in the cell list configured by the base station for the UE and in the RAN-NotificationAreaInfo IE. As another example, the terminal reads the TAC of the cell from the message and determines whether the read TAC belongs to the TAC included in the RAN area list configured by the base station for the UE and in the RAN-NotificationAreaInfo IE. The manner of determining whether the serving cell belongs to the configured RNA is not limited in the present application.

[0482] In some embodiments, after T380 expires or the UE receives SIB1 in a cell outside the UE's current RNA, the UE in RRC INACTIVE state needs to trigger the RRC connection resumption procedure, which is for RNAU. However, in practice, the UE does not need to perform RNAU because the network equipment can perceive the cell location of the UE performing SDT data transmission. Therefore, the triggering of RNAU needs to be avoided in the SDT procedure.

[0483] In some embodiments, T380 is stopped in an SDT procedure. For example, after an SDT procedure starts, the UE stops T380 when it receives a first response message corresponding to the UE's RRC request message from a network device. For example, the UE stops T380 when it receives a contention resolution MAC CE in the RA-SDT or receives an ACK in response to the RRCResumeRequest sent in the CG-SDT.

[0484] In some embodiments, an additional condition is introduced: RNAU can only be triggered when the SDT failure detection timer is not running, i.e., T380 expires without the first timer running. The SDT failure detection timer is started when the UE initiates an RRC connection resumption procedure that is for SDT. In other words, when the SDT failure detection timer is running, the UE is performing an SDT procedure. Therefore, an additional condition can be added to the current conditions for triggering periodic RNAU to avoid periodic RNAU being triggered when T380 expires.

[0485] It can be understood that the communication system architecture and service scenarios described in this application are intended to more clearly explain the technical solutions in this application, but do not constitute constraints on the technical solutions provided in this application. Those skilled in the art can recognize that with the evolution of communication system architectures and the emergence of new service scenarios, the technical solutions provided in this application can also be applied to similar technical problems.

[0486] Those skilled in the art can understand that all or part of the steps of the method in the above-mentioned embodiment can be implemented by a computer program that instructs the hardware associated with the computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed, the steps in the above-mentioned method embodiment can be included. The storage medium includes any medium that can store computer program code, such as a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

Claims

1. 1. A method performed by a device in a non-Radio Resource Control (RRC) connected state, comprising: performing an RRC connection resumption procedure for a radio access network based notification area update (RNAU) when a first preset condition is satisfied; the first preset condition includes a second timer expiring and a first timer not running; or The first preset condition includes: the device receives a system information block 1 (SIB1) of a first serving cell, the first serving cell does not belong to a configured radio access network-based notification area (RNA), and a first timer is not running; and When the device initiates an RRC connection resumption procedure for small data transmission (SDT), the first timer is started, and when the device receives an RRC release message including a duration of the second timer, the second timer is started. method.

2. stopping the first timer if an RRC reject message is received when the first timer is running; if the second timer is not running, setting a first variable to a first value, the first variable being at the first value indicating that there is an RNA update procedure pending; The method of claim 1 further comprising:

3. stopping the first timer if an RRC reject message is received when the first timer is running; performing the RRC connection resumption procedure for the RNAU if the second timer is not running; The method of claim 1 further comprising:

4. stopping the first timer if an RRC reject message is received when the first timer is running; if the second timer is not running, starting a third timer; performing the RRC connection resumption procedure for the RNAU if the third timer has expired and if the first timer is not running; The method of claim 1 further comprising:

5. setting a first variable to a first value when the first timer has expired and the second timer has not run, the first variable being at the first value indicating that there is an RNA update procedure pending. The method of claim 1 further comprising:

6. performing the RRC connection resumption procedure for the RNAU if the second timer is not running when the first timer expires. The method of claim 1 further comprising:

7. stopping the first timer when a cell reselection occurs while the first timer is running; receiving a SIB1 of a second serving cell, the second serving cell being a serving cell obtained through the cell reselection occurring on the device; setting a first variable to a first value when receiving the SIB1 of the second serving cell, if the second serving cell belongs to the configured RNA and the second timer is not running, wherein the first variable being at the first value indicates that there is a pending RNA update procedure; The method of claim 1 further comprising:

8. stopping the first timer when a cell reselection occurs while the first timer is running; receiving a SIB1 of a second serving cell, the second serving cell being a serving cell obtained through cell reselection occurring on the device; performing the RRC connection resumption procedure for the RNAU 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; The method of claim 1 further comprising:

9. stopping the first timer when a cell reselection occurs while the first timer is running; receiving a SIB1 of a second serving cell, the second serving cell being a serving cell obtained through cell reselection occurring on the device; 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; performing the RRC connection resumption procedure for the RNAU if the first timer is not running when the third timer expires; The method of claim 1 further comprising:

10. 8. The method of claim 7, wherein the non-RRC connected state comprises an RRC inactive state, and the device is in the RRC inactive state after a cell reselection occurs on the device.

11. After the step of setting the first variable to a first value, performing the RRC connection resumption procedure for the RNAU if the access prohibition is relaxed and if the higher layer does not request the RRC layer to perform an RRC connection resumption and if the first variable is the first value. The method of claim 2 , further comprising:

12. The method of claim 1 , wherein the non-RRC connected state comprises an RRC inactive state.

13. Apparatus, said apparatus configured to implement a method according to any one of claims 1 to 12.

14. 13. A computer storage medium having stored thereon a computer program which, when executed, implements the method of any one of claims 1 to 12.

15. A computer program, which, when executed, implements a method according to any one of claims 1 to 12.

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