Method, device and system for small data transmission

Abstract

The present disclosure describes methods, systems, and devices for configuring small data transmission in a communication system. The method includes performing, by a first network node, a small data transmission (SDT) transmission for a user equipment (UE) by sending, by the first network node, a paging message to a second network node, the paging message configured to request the second network node to page the UE for the SDT transmission, wherein the paging message includes SDT information, and the second network node pages the UE according to the SDT information.

Description

Technical Field

[0001] This disclosure generally relates to wireless communications. Specifically, this disclosure relates to methods, apparatus, and systems for transmitting small data when a user equipment is inactive. Background Technology

[0002] Wireless communication technology is propelling the world towards an increasingly interconnected and networked society. High-speed and low-latency wireless communication relies on efficient network resource management and allocation between user equipment and wireless access network nodes (including but not limited to base stations). Next-generation networks promise to provide high-speed, low-latency, and ultra-reliable communication capabilities, meeting the needs of various industries and users.

[0003] With the rapid evolution of cellular mobile communication systems, wireless networks support various types of services, each with different requirements for data packet transmission. These requirements include, for example, payload size, transmission latency, transmission reliability, and transmission priority. When the User Equipment (UE) is in inactive or idle mode, it is crucial for the UE to support data transmission with efficient utilization of radio resources while reducing power consumption, especially for relatively small amounts of data to be transmitted.

[0004] This disclosure describes various embodiments for configuring small data transmission that can address at least one of the issues / problems associated with existing systems, particularly those related to downlink small data transmission, thereby reducing the load on the radio access network, lowering the power consumption of the UE, and improving the efficiency and / or performance of wireless communication. Summary of the Invention

[0005] This document relates to methods, systems, and apparatuses for wireless communication, and more specifically, to methods, systems, and apparatuses for configuring small data transmission when a user equipment is in an inactive or idle state. Various embodiments of this disclosure can improve resource utilization efficiency, enhance the latency performance of wireless communication, and conserve power consumption of user equipment.

[0006] In one embodiment, this disclosure describes a method for wireless communication. The method includes a first network node performing a Small Data Transmission (SDT) transmission to a User Equipment (UE) by sending a paging message to a second network node, the paging message being configured to request the second network node to page the UE for SDT transmission, wherein the paging message includes SDT information, and the second network node pagees the UE based on the SDT information.

[0007] In one embodiment, this disclosure describes a method for wireless communication. The method includes a second network node performing a Small Data Transmission (SDT) to a User Equipment (UE) by receiving a paging message from a first network node, the paging message being configured to request the second network node to page the UE for SDT transmission, wherein the paging message includes SDT information, and the second network node pagees the UE based on the SDT information.

[0008] In some other embodiments, an apparatus for wireless communication may include a memory storing instructions and processing circuitry communicating with the memory. When the processing circuitry executes the instructions, the processing circuitry is configured to perform the methods described above.

[0009] In some other embodiments, a device for wireless communication may include a memory storing instructions and processing circuitry communicating with the memory. When the processing circuitry executes the instructions, the processing circuitry is configured to perform the methods described above.

[0010] In some other embodiments, a computer-readable medium includes instructions that, when executed by a computer, cause the computer to perform the methods described above.

[0011] The above and other aspects and their embodiments are described in more detail in the accompanying drawings, description and claims. Attached Figure Description

[0012] Figure 1A A schematic diagram of a wireless communication system is shown.

[0013] Figure 1B A schematic diagram of a base station is shown.

[0014] Figure 2 An example of a network node is shown.

[0015] Figure 3 An example of a user device is shown.

[0016] Figure 4A A flowchart of a method for wireless communication is shown.

[0017] Figure 4B A flowchart of another method for wireless communication is shown.

[0018] Figure 5 A flowchart illustrating an exemplary embodiment for wireless communication is shown.

[0019] Figure 6 A flowchart illustrating an exemplary embodiment for wireless communication is shown.

[0020] Figure 7A flowchart illustrating an exemplary embodiment for wireless communication is shown.

[0021] Figure 8 A flowchart illustrating an exemplary embodiment for wireless communication is shown.

[0022] Figure 9 A flowchart illustrating an exemplary embodiment for wireless communication is shown.

[0023] Figure 10 A flowchart illustrating an exemplary embodiment for wireless communication is shown.

[0024] Figure 11 A flowchart illustrating an exemplary embodiment for wireless communication is shown.

[0025] Figure 12 A flowchart illustrating an exemplary embodiment for wireless communication is shown.

[0026] Figure 13 A flowchart illustrating an exemplary embodiment for wireless communication is shown. Detailed Implementation

[0027] This disclosure will now be described in detail with reference to the accompanying drawings, which form a part of this disclosure and illustrate specific examples of embodiments by way of illustration. However, it should be noted that this disclosure may be implemented in a variety of different forms, and therefore, the subject matter covered or claimed is intended to be construed as not being limited to any of the embodiments set forth below.

[0028] Throughout the specification and claims, terms may have nuanced meanings suggested or implied in the context beyond their explicitly stated meanings. Similarly, the phrases “in one embodiment” or “in some embodiments” as used herein do not necessarily refer to the same embodiment, and the phrases “in another embodiment” or “in other embodiments” as used herein do not necessarily refer to different embodiments. For example, it is intended that the claimed subject matter encompasses, in whole or in part, combinations of exemplary embodiments or embodiments.

[0029] Generally, terms can be understood at least in part from their usage in the context. For example, terms such as “and,” “or,” or “and / or” as used herein can include a variety of meanings that may depend at least in part on the context in which they are used. Typically, “or,” when used in an associative list (such as A, B, or C), is intended to mean A, B, and C (used herein in an inclusive sense) and A, B, or C (used herein in an exclusive sense). Furthermore, depending at least in part on the context, the terms “one or more” or “at least one” as used herein may be used to describe any feature, structure, or characteristic in a singular sense, or may be used to describe a combination of features, structures, or characteristics in a plural sense. Similarly, depending at least in part on the context, terms such as “a,” “an,” or “the” may also be understood to convey either a singular or a plural usage. Moreover, the terms “based on” or “determined by” can be understood not necessarily to convey an exclusive set of factors, but rather, also depending at least in part on the context, may allow for additional factors that are not necessarily explicitly described.

[0030] With the development of smart terminals (e.g., User Equipment (UE)) and Internet of Things (IoT) terminals, the number of users of instant messaging services (such as WeChat, Twitter, QQ Message, and other applications) is increasing. These services are typically always online and primarily target small data transfers (SDTs) (such as text messages). Traditionally, user data transfer is not allowed when the device is inactive. Even for very small data transfers, the device must reconnect, which can negatively impact signaling overhead and device power consumption. Because small data transfer services require the UE to frequently re-establish signaling links with the RAN wireless network, this leads to problems such as increased signaling load on the RAN and increased power consumption on the UE.

[0031] In some implementations, the payload for Small Data Transmission (SDT) can be generated in an inactive state. For the New Radio (NR) specification, a UE can have three states: idle, inactive, and connected. A UE cannot transmit data in the idle or inactive state, so when a UE wants to transmit data in either the idle or inactive state, it first transitions to the connected state. However, for Small Data Transmission (SDT), a UE can transmit small data in the inactive state without first transitioning to the connected state. The idle / inactive version, which cannot transmit data, can be referred to as the Legacy state, compared to the states presented here that allow small data transmission in either the inactive or idle state.

[0032] Any device with intermittent small data packets in an inactive state can benefit from enabling Small Data Transmission (SDT) while inactive. SDT services can have different service requirements compared to regular or larger data transmission service types. While inactive, the UE can / can communicate with other UEs via SDT or transmit data. The UE can send an SDT request message to a base station, which can be a nodeB (NB, e.g., eNB or gNB) in the mobile telecommunications context. The base station can respond to the UE request message with a reply including an SDT indication. Even in inactive, the UE can perform SDT indication signaling communication. Performing small data transmission while inactive can save power and reduce signaling overhead.

[0033] In some implementations, SDT communication can coexist with traditional hybrid services on the same carrier while improving the use of network resources (power, code, interference, etc.) for SDT communication. Examples of small and infrequent data services eligible for SDT include smartphone applications such as: 1) services from instant messaging services (e.g., WhatsApp, QQ, WeChat, etc.); 2) heartbeat / keep-alive services from IM / email clients and other applications; and 3) push notifications from various applications. Furthermore, other SDTs may include services from wearable devices (periodic location information, etc.), sensors (e.g., industrial wireless sensor networks that periodically or event-triggeredly transmit temperature or pressure readings), and smart meters or smart meter networks that transmit periodic instrument readings.

[0034] In various embodiments, small data in the SDT may include data with an application packet size of 100 bytes or less (upload UL or download DL). Although the examples and embodiments described herein relate to small data or small data transfers, the scope of small data can vary and may include data other than small data (such as normal data or large data). Specifically, the size of small data can vary and the embodiments / examples described will be applicable to any data.

[0035] Radio Resource Control (RRC) is a protocol layer at the IP level (network layer) between the UE and the base station. RRC messages are transmitted via the Packet Data Convergence Protocol (PDCP). As described, the UE can send infrequent (periodic and / or aperiodic) data in an RRC inactive (RRC_INACTIVE) state without transitioning to an RRC_CONECTED state. This saves UE power consumption and signaling overhead. This can be achieved through the Random Access Channel (RACH) protocol scheme or the Configured Grant (CG) scheme.

[0036] In some implementations, a UE in an RRC-inactive state can restore the RRC connection (i.e., switch to an RRC-connected state) and then perform any downlink (DL) and uplink (UL) data transmissions, regardless of the payload size. In other implementations, to meet increasing requirements for latency reduction and energy efficiency, infrequent small packet transmissions under SDT enable a UE in an RRC-inactive state to perform data transmissions without switching to an RRC-connected state.

[0037] In some implementations, SDT is enabled on top of the radio bearer, and the UE initiates SDT only when less than the configured amount of UL (uplink) data is waiting to be transmitted in all radio bearers where SDT is enabled. In other implementations, only the UE can initiate the SDT procedure for UL data. Therefore, when infrequent and small amounts of DL data arrive at the gNB for a UE in an RRC inactive state, the gNB can only request the UE to transition from the RRC inactive state to the RRC_CONNECTED state for subsequent DL data transmission. Thus, additional transmission latency is introduced for DL ​​SDT data, and power consumption on the UE becomes greater.

[0038] This disclosure describes various embodiments for configuring small data transmission, which can be initiated by the base station or core network when infrequent and small amounts of DL data arrive for a UE in an RRC inactive state, thereby addressing at least one of the aforementioned problems / issues.

[0039] Figure 1AAn example cellular wireless communication network 100 (also known as a wireless communication system) is shown, comprising a core network 110, a radio access network (RAN) 120, and one or more user equipment (UE) 130.

[0040] RAN 120 also includes multiple base stations 122 and 124. Base station 122 and one or more user equipment (UE) 130 communicate with each other via over-the-air (OTA) wireless communication resource 140 (also referred to as OTA 140 or OTA interface 140). Wireless communication network 100 can be implemented as, for example, a 2G, 3G, 4G / LTE, or 5G cellular communication network. Accordingly, base stations 122 and 124 can be implemented as 2G base stations, 3G NodeBs, LTE eNBs, or 5G New Radio (NR) gNBs. UE 130 can be implemented as a mobile or fixed communication device equipped with a SIM / USIM (Subscriber Identity Module / Universal Subscriber Identity Module) module for accessing wireless communication network 100. One or more UE 130s may include, but are not limited to, mobile phones, Internet of Things (IoT) devices, Machine-Type Communications (MTC) devices, laptops, tablets, personal digital assistants, wearable devices, distributed remote sensor devices, roadside assistance devices, and desktop computers. As an alternative to the context of cellular wireless networks, RAN 120 and the principles described below can be implemented as other types of wireless access networks, such as Wi-Fi, Bluetooth, ZigBee, and World Interoperability for Microwave Access (WiMax) networks.

[0041] exist Figure 1A In the example wireless communication system 100, UE 130 can connect to base station 122 and establish a communication session via OTA interface 140. The communication session between UE 130 and base station 122 can utilize downlink (DL) and / or uplink (UL) transmission resources. DL transmission resources carry data from base station 122 to UE 130, while UL transmission resources carry data from UE 130 to base station 122. In certain situations, such as when base station 122 is unavailable or when UE 130 moves to the coverage of base station 124, one or more UEs 130 can connect to base station 124 and establish a communication session with base station 124.

[0042] refer to Figure 1B The base station (e.g., gNB) 150 may have a distributed control structure, which may include a control unit (CU) 160 and one or more distributed units (DUs) 171, 172, and / or 173. The CU may include a control plane (CP) 161 and a user plane (UP) 162. CP 161 may be referred to as CU-CP or gNB-CU-CP, and UP 162 may be referred to as CU-UP or gNB-CU-UP. CU-CP 161 may communicate with CU-UP 162 via an E1 interface between CU-CP 161 and CU-UP 162. CU-CP 161 may communicate with one or more DUs via an F1-C interface, and CU-UP 162 may communicate with one or more DUs via an F1-U interface.

[0043] Figure 2 An example of an electronic device 200 for implementing a network base station is shown. The example electronic device 200 may include wireless transmit / receive (Tx / Rx) circuitry 208 for transmitting / receiving communications with a UE and / or other base stations. The electronic device 200 may also include network interface circuitry 209 to enable the base station to communicate with other base stations and / or the core network (e.g., via optical or wired interconnects, Ethernet, and / or other data transmission media / protocols). The electronic device 200 may optionally include an input / output (I / O) interface 206 for communication with operators, etc.

[0044] Electronic device 200 may also include system circuitry 204. System circuitry 204 may include one or more processors 221 and / or memory 222. Memory 222 may include operating system 224, instructions 226, and parameters 228. Instructions 226 may be configured for use by one or more processors 221 to perform functions of the network node. Parameters 228 may include parameters that support the execution of instructions 226. For example, parameters may include network protocol settings, bandwidth parameters, radio frequency mapping allocation, and / or other parameters.

[0045] Figure 3An example of an electronic device for implementing a terminal device 300 (e.g., a user equipment (UE) 300) is shown. The UE 300 may be a mobile device, such as a smartphone or a mobile communication module installed in a vehicle. The UE 300 may include a communication interface 302, system circuitry 304, input / output interfaces (I / O) 306, display circuitry 308, and storage device 309. The display circuitry 308 may include a user interface 310. The system circuitry 304 may include any combination of hardware, software, firmware, or other logic / circuit. The system circuitry 304 may be implemented, for example, using one or more systems-on-a-chip (SoC), application-specific integrated circuits (ASICs), discrete analog and digital circuits, and other circuits. The system circuitry 304 may be part of an implementation of any desired functionality in the UE 300. In this regard, system circuitry 304 may include logic that facilitates operations such as: decoding and playing music and video (e.g., MP3, MP4, MPEG, AVI, FLAC, AC3, or WAV decoding and playback); running applications; accepting user input; saving and retrieving application data; establishing, maintaining, and terminating cellular phone calls or data connections (e.g., an internet connection, as an example); establishing, maintaining, and terminating wireless network connections, Bluetooth connections, or other connections; and displaying relevant information on user interface 310. User interface 310 and input / output (I / O) interface 306 may include a graphical user interface, a touch-sensitive display, haptic feedback or other haptic outputs, voice or facial recognition inputs, buttons, switches, speakers, and other user interface elements. Additional examples of I / O interface 306 may include a microphone, video and still image cameras, temperature sensors, vibration sensors, rotation and orientation sensors, headphone and microphone input / output jacks, a Universal Serial Bus (USB) connector, a memory card slot, a radiation sensor (e.g., an IR sensor), and other types of inputs.

[0046] refer to Figure 3The communication interface 302 may include radio frequency (RF) transmit (Tx) and receive (Rx) circuitry (Tx / Rx circuitry) 316, which processes the transmission and reception of signals via one or more antennas 314. The communication interface 302 may include one or more transceivers. The transceiver may be a wireless transceiver, including modulation / demodulation circuitry, a digital-to-analog converter (DAC), a shaper, an analog-to-digital converter (ADC), filters, waveform shapers, pre-amplifiers, power amplifiers, and / or other logic for transmission and reception via one or more antennas or (for some devices) via a physical (e.g., wired) medium. The transmitted and received signals may conform to any of a wide variety of formats, protocols, modulations (e.g., QPSK, 16-QAM, 64-QAM, or 256-QAM), frequency channels, bit rates, and encodings. As a specific example, communication interface 302 may include transceivers supporting transmission and reception under the following standards: 2G, 3G, BT, WiFi, Universal Mobile Telecommunications System (UMTS), High Speed ​​Packet Access (HSPA)+, 4G / Long Term Evolution (LTE), 5G standards, and / or 6G standards. However, the technologies described below, whether derived from the 3rd Generation Partnership Project (3GPP), the GSM Association, 3GPP2, IEEE, or other partners or standards bodies, are applicable to other wireless communication technologies.

[0047] refer to Figure 3 System circuitry 304 may include one or more processors 321 and memory 322. Memory 322 stores, for example, an operating system 324, instructions 326, and parameters 328. Processor 321 is configured to execute instructions 326 to achieve the desired functionality of UE 300. Parameters 328 can provide and specify configuration and operational options for instructions 326. Memory 322 may also store any BT, WiFi, 3G, 4G, 5G, 6G, or other data that UE 300 will send or has received via communication interface 302. In various embodiments, system power for UE 300 may be provided by power storage devices such as batteries or transformers.

[0048] This disclosure describes various embodiments for configuring small data transfers, which may be partially or wholly described above. Figures 2 to 3 The network base stations and / or user equipment described herein are implemented. Various embodiments of this disclosure can address issues / problems related to downlink small data transmission, thereby reducing the load on the radio access network, lowering UE power consumption, and improving the efficiency and / or performance of wireless communication.

[0049] refer to Figure 4A This disclosure describes various embodiments of a method 400 for wireless communication. Method 400 may include: performing a Small Data Transmission (SDT) transmission to a User Equipment (UE) by a first network node. Method 400 may include: step 410, whereby the first network node sends a paging message to a second network node, the paging message being configured to request the second network node to page the UE for SDT transmission, wherein the paging message includes SDT information, and the second network node pages the UE based on the SDT information.

[0050] refer to Figure 4B This disclosure describes various embodiments of a method 450 for wireless communication. Method 450 may include: performing a small data transmission (SDT) transmission to a user equipment (UE) by a second network node. Method 450 may include: step 460, whereby the second network node receives a paging message from a first network node, the paging message being configured to request the second network node to page the UE for SDT transmission, the paging message including SDT information, and the second network node pagees the UE based on the SDT information.

[0051] In various embodiments and / or implementations of this disclosure, a network node may be referred to as a network element.

[0052] In some implementations, the first network node may be referred to as a first network element or a source network element, such as, but not limited to, a control unit of a base station. In some implementations, the second network node may be referred to as a second network element or a target network element, such as, but not limited to, a distributed unit of a base station.

[0053] In some implementations, the first network node is a base station control unit (gNB-CU) and the second network node is a base station distributed unit (gNB-DU); or the first network node is a first gNB and the second network node is a second gNB.

[0054] In some implementations, the first network node is gNB-CU; the control plane entity (gNB-CU-CP) of gNB-CU sends a message to the user plane entity (gNB-CU-UP) of gNB-CU, the message including SDT trigger parameters; and the SDT trigger parameters include at least one of the following: a data volume threshold for the UE, a data volume threshold for a Protocol Data Unit (PDU) session, or a data volume threshold for a bearer configured with SDT transmission.

[0055] In some implementations, the first network node is gNB-CU; in response to receiving downlink (DL) data, gNB-CU-UP determines whether to use SDT transmission to send the received DL data based on SDT trigger parameters; and in response to gNB-CU-UP determining to use SDT transmission to send the received DL data, gNB-CU-UP sends a message to gNB-CU-CP to notify of the arrival of DL data, the message including SDT information and / or SDT data indicating the expected SDT transmission, wherein the SDT data includes at least a portion of the received DL data sent to the UE.

[0056] In some implementations, gNB-CU-UP determines whether to use SDT transmission to send the received DL data based on at least one of the following SDT trigger parameters: gNB-CU-UP determines to use SDT transmission to send the received DL data in response to the SDT trigger parameters including a data volume threshold for the UE and the data volume of the received DL data for all bearers configured with SDT for the UE not exceeding the data volume threshold for the UE; gNB-CU-UP determines to use SDT transmission to send the received DL data in response to the SDT trigger parameters including a data volume threshold for the PDU session and the data volume of the received DL data for all bearers configured with SDT for the PDU session not exceeding the data volume threshold for the PDU session; or gNB-CU-UP determines to use SDT transmission to send the received DL data in response to the SDT trigger parameters including a data volume threshold for the bearer and the data volume of the received DL data for the bearer not exceeding the data volume threshold for the bearer.

[0057] In some implementations, the paging message includes SDT data, wherein the SDT data includes at least a portion of the received DL data sent to the UE.

[0058] In some implementations, before the second network node pages the UE based on SDT information: in response to receiving a paging message, the second network node sends a Paging Early Indication (PEI) message to the UE, which includes SDT information indicating the transmission of SDT.

[0059] In some implementations, the second network node pages the UE based on SDT information by sending a Radio Resource Control (RRC) paging message to the UE, the RRC paging message including SDT information indicating SDT transmission.

[0060] In some implementations, in response to receiving an RRC paging message from a second network node, the UE sends an RRC recovery request message to the second network node. The RRC recovery request message includes an SDT indicator to request the recovery of the inactive UE for SDT transmission.

[0061] In some implementations, the core network (CN) sends a message to a first network node to request the transmission of a Non-Access Stratum (NAS) PDU to the UE. The message includes either a single NAS PDU indicator or a multiple NAS PDU indicator. The single NAS PDU indicator indicates that no subsequent NAS PDU transmission is expected, while the multiple NAS PDU indicator indicates that at least one subsequent NAS PDU transmission is expected.

[0062] In some implementations, the message includes a downlink NAS transmission message.

[0063] In some implementations, the first network node is gNB-CU; and gNB-CU-CP determines whether to relocate the UE context to a nearby gNB based on SDT information received from gNB-CU-UP in the following manner: in response to the UE subsequently recovering at a nearby gNB and the SDT information including a multi-packet indicator, gNB-CU-CP determines to relocate the UE context to a nearby gNB.

[0064] In some implementations, the SDT information includes at least one of the following: an SDT indicator indicating that an SDT transmission is expected; a single packet indicator indicating that no subsequent SDT transmission is expected; or a multi-packet indicator indicating that at least one subsequent SDT transmission is expected.

[0065] This disclosure describes various embodiments having non-limiting exemplary examples for configuring Small Data Transfer (SDT).

[0066] I: An example of configuring SDT triggering parameters for multiple UEs at gNB-CU-UP via E1.

[0067] Figure 5 Two options (or alternatives) are shown for configuring SDT triggering parameters for multiple UEs at gNB-CU-UP via the E1 interface establishment procedure: Option 1, gNB-CU-UP initiates the E1 establishment procedure; and Option 2, gNB-CU-CP initiates the E1 establishment procedure. The E1 interface can refer to the interface between gNB-CU-CP and gNB-CU-UP.

[0068] Regarding option 1 (510), in step 501a.1, gNB-CU-UP 592 initiates the E1 interface establishment process by sending a GNB-CU-UP E1 SETUP REQUEST message to gNB-CU-CP 591. In step 501a.2, after receiving the GNB-CU-UP E1 SETUP REQUEST message, gNB-CU-CP sends a GNB-CU-UP E1 SETUP RESPONSE message to gNB-CU-UP, including SDT trigger parameters. These SDT trigger parameters include at least a data volume threshold configured for the UE, or for the PDU session, or for a bearer configured with SDT. The E1 interface is then successfully established to exchange the application-level data required by gNB-CU-UP and gNB-CU-CP.

[0069] Regarding option 2 (520), in step 501b.1, gNB-CU-CP initiates the E1 interface establishment process by sending a GNB-CU-CP E1 SETUP REQUEST message to gNB-CU-UP, which includes SDT trigger parameters, wherein the SDT trigger parameters include at least a data volume threshold configured for the UE, or for the PDU session, or for the bearer configured with SDT. In step 501b.2, after receiving the GNB-CU-CP E1 SETUP REQUEST message, gNB-CU-UP sends a gNB-CU-CPE1 SETUP RESPONSE message to gNB-CU-CP, and then the E1 interface is successfully established to exchange the application-level data required by gNB-CU-UP and gNB-CU-CP.

[0070] Following option 1 or option 2, in step 502, gNB-CU-UP stores the received SDT trigger parameters for the UE served by gNB-CU-UP.

[0071] II. An example of configuring SDT triggering parameters for multiple UEs at gNB-CU-UP via E1 modification

[0072] Figure 6Two options (or alternatives) for configuring SDT triggering parameters for multiple UEs at gNB-CU-UP via an E1 interface modification procedure are shown: Option 1, gNB-CU-UP initiates the E1 modification procedure; and Option 2, gNB-CU-CP initiates the E1 modification procedure. The E1 interface can refer to the interface between gNB-CU-CP and gNB-CU-UP.

[0073] Regarding option 1 (610), in step 601a.1, gNB-CU-UP 692 initiates the E1 modification process by sending a GNB-CU-UP CONFIGURATION UPDATE message to gNB-CU-CP 691. In step 601a.2, after receiving the GNB-CU-UP CONFIGURATION UPDATE message, gNB-CU-CP sends a GNB-CU-UP CONFIGURATION UPDATE ACKNOWLEDGE message to gNB-CU-UP, including SDT trigger parameters, where the SDT trigger parameters include at least a configuration data volume threshold for the UE, for the PDU session, or for a bearer configured with SDT. The E1 interface is then successfully modified to exchange the application-level data required by gNB-CU-UP and gNB-CU-CP.

[0074] Regarding option 2 (620), in step 601b.1, gNB-CU-CP initiates the E1 modification procedure by sending a GNB-CU-CP CONFIGURATION UPDATE message to gNB-CU-UP, which includes SDT trigger parameters, wherein the SDT trigger parameters include at least a configuration data volume threshold for the UE, or for the PDU session, or for the bearer configured with SDT. In step 601b.2, after receiving the GNB-CU-CP CONFIGURATION UPDATE message, gNB-CU-UP sends a GNB-CU-CP CONFIGURATION UPDATE ACKNOWLEDGE message to gNB-CU-CP, and then the E1 interface is successfully modified to exchange the application-level data required by gNB-CU-UP and gNB-CU-CP.

[0075] Following option 1 or option 2, in step 602, gNB-CU-UP stores the received SDT trigger parameters for the UE served by gNB-CU-UP.

[0076] III. Example of configuring SDT triggering parameters for the UE at gNB-CU-UP via bearer context establishment

[0077] Figure 7A non-limiting example of configuring SDT triggering parameters for a UE at gNB-CU-UP via bearer context establishment is shown. In step 701, gNB-CU-CP 791 sends a BEARER CONTEXT SETUPREQUEST message to gNB-CU-UP 792 to request gNB-CU-UP to establish the requested resources for the UE. This message includes the UE's SDT triggering parameters, wherein the SDT triggering parameters include at least a configuration data volume threshold for the UE, a PDU session, or a bearer configured with SDT. In step 702, after receiving the BEARER CONTEXT SETUPREQUEST message, gNB-CU-UP can establish the requested resources for the UE and send a BEARER CONTEXT SETUP RESPONSE message to gNB-CU-CP. In step 703: gNB-CU-UP stores the received SDT triggering parameters for the UE.

[0078] IV. Example of configuring SDT triggering parameters for UE at gNB-CU-UP via bearer context modification

[0079] Figure 8 Two options (or alternatives) for configuring SDT triggering parameters for the UE at gNB-CU-UP via a bearer modification procedure are shown: Option 1, gNB-CU-UP initiates the bearer modification procedure; and Option 2, gNB-CU-CP initiates the bearer modification procedure.

[0080] Regarding option 1 (810), in step 801a.1, gNB-CU-UP 892 sends a BEARERCONTEXT MODIFICATION REQUIRED message to gNB-CU-CP 891 to modify the bearer configuration of the UE. In step 801a.2, after receiving the BEARER CONTEXT MODIFICATION REQUIRED message, gNB-CU-CP modifies the bearer configuration and sends a BEARER CONTEXT MODIFICATIONCONFIRM message to gNB-CU-UP, which includes the SDT trigger parameters of the UE, wherein the SDT trigger parameters include at least a configuration data volume threshold for the UE, for the PDU session, or for the bearer configured with SDT.

[0081] Regarding option 2 (820), in step 801b.1, the gNB-CU-CP sends a BEARER CONTEXTMODIFICATION REQUEST message to the gNB-CU-UP to request the gNB-CU-UP to modify the requested resources for the UE. This message includes the UE's SDT triggering parameters, wherein the SDT triggering parameters include at least a configuration data volume threshold for the UE, the PDU session, or the bearer configured with SDT. In step 801b.2, after receiving the BEARERCONTEXT MODIFICATION REQUEST message, the gNB-CU-UP may modify the requested resources for the UE and send a BEARER CONTEXT MODIFICATION RESPONSE message to the gNB-CU-CP.

[0082] Following option 1 or option 2, in step 802, gNB-CU-UP stores the SDT trigger parameters received by the UE.

[0083] V. Implementation Example for Sending Downlink (DL) SDT Triggered by gNB-CU-UP

[0084] Figure 9 A non-limiting exemplary example is shown for initiating and transmitting a downlink (DL) SDT triggered by gNB-CU-UP.

[0085] Referring to step 900, UE 991 is connecting to the RAN in RRC inactive mode (i.e., the UE is in RRC inactive state). The RAN may include one or more gNB-DU 992, one or more gNB-CU-CP 993, and one or more gNB-CU-UP 994.

[0086] Referring to step 901, when DL data with SDT configured on one or more bearers arrives for a UE in an RRC inactive state, the gNB-CU-UP determines whether to use SDT transmission for the UE based on the stored SDT trigger parameters. The SDT trigger parameters can be obtained and / or stored as described in previous embodiments of this disclosure.

[0087] When there is a configuration data volume threshold for the UE, if the arrival data volume of all (one or more) bearers configured with SDT for the UE is less than (or not greater than) the corresponding configuration threshold, gNB-CU-UP can determine to use SDT transmission.

[0088] When a configuration data volume threshold exists for a PDU session, gNB-CU-UP can determine to use SDT transmission when the arriving data volume of all (one or more) bearers configured with SDT for that PDU session is less than (or not greater than) the corresponding configuration threshold.

[0089] When there is a configuration data volume threshold for a bearer configured with SDT, gNB-CU-UP can determine to use SDT transmission when the amount of arriving data for that SDT bearer is less than (or not greater than) the corresponding configuration threshold.

[0090] Referring to step 902, when gNB-CU-UP determines that SDT transmission is to be used for the UE, gNB-CU-UP sends a DL DATA NOTIFICATION message to gNB-CU-CP to notify that DL data has arrived. This DL DATA NOTIFICATION message may include SDT information for requesting the resumption of SDT transmission for the UE. The SDT information includes at least one of the following: an SDT indicator indicating that SDT transmission is expected; a single-packet indicator indicating that no further SDT transmission is expected; or a multi-packet indicator indicating that further SDT transmission is expected.

[0091] In some implementations, gNB-CU-UP can determine various aspects of the SDT information. For example, when gNB-CU-UP decides to use SDT transmission, gNB-CU-UP may include an SDT indicator; when only one packet needs to be sent to the UE, gNB-CU-UP may include a single packet indicator; when multiple packets need to be sent to the UE, gNB-CU-UP may include a multiple packet indicator.

[0092] Optionally, in some implementations, gNB-CU-UP may include some SDT data (e.g., one or more Packet Data Convergence Protocol (PDCP) PDUs for configuring one or more bearers with SDT) that need to be sent to the UE in the DL DATA NOTIFICATION message.

[0093] Referring to step 903, after receiving the DL DATA NOTIFICATION message, if SDT information exists in the DL DATA NOTIFICATION message, the gNB-CU-CP sends an F1 paging message to the gNB-DU to notify the UE corresponding to the DU to perform SDT transmission. The F1 paging message includes SDT information. The SDT information includes at least one of the following: an SDT indicator indicating that SDT transmission is expected; a single-packet indicator indicating that no subsequent SDT transmission is expected; or a multi-packet indicator indicating that subsequent SDT transmission is expected.

[0094] Optionally, in some implementations, gNB-CU-CP may include some SDT data (one or more PDCP PDUs for configuring one or more bearers with SDT) received from gNB-CU-UP via the DL DATA NOTIFICATION message into the F1 paging message. In some implementations, the SDT information here may not need to include all SDT information received from gNB-CU-UP; for example, it may only include a portion of the received information, such as only the SDT indicator.

[0095] In some implementations, when the UE subsequently recovers at a nearby gNB, the gNB-CU-CP can use the SDT information received from the gNB-CU-UP to determine whether to relocate the UE context to the nearby gNB. For example, when a multi-packet indicator is present in the SDT information, the gNB-CU-CP can decide to relocate the UE context to the nearby gNB.

[0096] For gNB-DU to transmit SDT information to UE, there are two options (or alternatives): Option 1, gNB-DU includes SDT information in Paging Early Indication (PEI) message; and Option 2, gNB-DU includes SDT information in RRC paging message.

[0097] For option 1 (910), in step 904a.1, after receiving the F1 paging message, the gNB-DU sends a PEI message to the UE before paging the UE. This PEI message includes SDT information to indicate SDT transmission. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information here may not need to include all SDT information received from the gNB-CU; for example, it may only include a portion of the received information, such as only the SDT indicator. In step 904a.2, the gNB-DU sends an RRC paging message to the UE to page the corresponding UE.

[0098] Regarding option 2 (920), in step 904b, the gNB-DU sends an RRC paging message to the UE to page the corresponding UE for SDT transmission, the message including SDT information. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information here may not need to include all SDT information received from the gNB-CU; for example, it may only include a portion of the received information, such as only the SDT indicator.

[0099] In some implementations, after receiving an RRC paging message, when the UE receives SDT information from the RRC paging message or PEI message, the UE may decide to restore the inactive UE to perform SDT transmission.

[0100] In some implementations, when the UE is configured with reserved Cell Group (CG) resources and the UE receives a multi-packet indicator in the SDT information, the UE may prefer to use the reserved CG resources for SDT data transmission; and / or when the UE receives a single-packet indicator in the SDT information, the UE may prefer to use the Random Access Channel (RACH) resources for SDT data transmission.

[0101] Referring to step 905, the UE sends an RRC recovery request message to the gNB-DU, which includes an SDT indicator to indicate that an SDT transmission is expected, in order to request the recovery of the inactive UE for SDT transmission.

[0102] Referring to step 906, the UE is restored to an RRC inactive state at the gNB, and subsequent SDT data is sent / received between the UE and the gNB via RACH or CG resources.

[0103] VI. Example of sending a DL SDT triggered by a nearby gNB

[0104] Figure 10 A non-limiting exemplary example of initiating and transmitting a downlink (DL) SDT triggered by a neighboring gNB is shown. Referring to step 1000, UE 1091 is connected to the RAN in RRC inactive mode. The RAN can be the first gNB (gNB1, 1092) and the neighboring gNB (gNB2, 1093). gNB1 is the last serving gNB.

[0105] Referring to step 1001, when DL data of one or more bearers configured with SDT arrives at gNB1 for a UE in an RRC inactive state, gNB1 can determine whether to use SDT transmission for the UE based on the stored SDT trigger parameters. When a configuration data volume threshold exists for the UE, gNB1 can determine to use SDT transmission if the arriving data volume of all (one or more) bearers configured with SDT for that UE is less than (or not greater than) the corresponding configuration threshold; and / or when a configuration data volume threshold exists for a PDU session, gNB1 can determine to use SDT transmission if the arriving data volume of all (one or more) bearers configured with SDT for that PDU session is less than (or not greater than) the corresponding configuration threshold; and / or when a configuration data volume threshold exists for a bearer configured with SDT, gNB1 can determine to use SDT transmission if the arriving data volume of that SDT bearer is less than (or not greater than) the corresponding configuration threshold. In some implementations, the SDT trigger parameters can be configured in gNB1 by the Operation Management and Maintenance (OAM) unit.

[0106] Referring to step 1002, when gNB1 decides to use SDT transmission for the UE, gNB1 sends a RAN paging message to the neighboring gNB2 to notify gNB2 to page the corresponding UE for SDT transmission. This message includes SDT information. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; and a multi-packet indicator indicating expected subsequent SDT transmission. gNB1 can determine the items in the SDT information. When gNB1 decides to use SDT transmission, gNB1 may include an SDT indicator; when only one packet needs to be sent to the UE, gNB1 may include a single-packet indicator; and / or when multiple packets need to be sent to the UE, gNB1 may include a multi-packet indicator.

[0107] Optionally, in some implementations, gNB1 may include some received SDT data (for one or more PDCP PDUs of bearers configured with SDT) in the RAN paging message.

[0108] There are two options (or alternatives) for gNB2 to transmit SDT information to UE: Option 1, gNB2 includes SDT information in the Early Paging Indication (PEI) message; and Option 2, gNB2 includes SDT information in the RRC paging message.

[0109] Referring to option 1 (1010), in step 1003a.1, after receiving the RAN paging message, gNB2 sends a PEI message to the UE before paging the UE. The PEI message includes SDT information indicating SDT transmission. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information may not need to include all SDT information received from gNB1; for example, it may only include a portion of the received information, such as only the SDT indicator. In step 1003a.2, gNB2 sends an RRC paging message to the UE to page the corresponding UE.

[0110] Regarding option 2 (920), in step 1003b, gNB2 sends an RRC paging message to the UE to page the corresponding UE for SDT transmission, the message including SDT information. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information here may not need to include all SDT information received from gNB1; for example, it may only include a portion of the received information, such as only the SDT indicator.

[0111] In some implementations, after receiving an RRC paging message, when the UE receives SDT information from the RRC paging message and / or PEI message, the UE may decide to restore the inactive UE to perform SDT transmission.

[0112] In some implementations, when the UE is configured with reserved CG resources and the UE receives a multi-packet indicator in the SDT information, the UE may prefer to use the reserved CG resources for SDT data transmission; and / or when the UE receives a single-packet indicator in the SDT information, the UE may prefer to use the Random Access Channel (RACH) resources for SDT data transmission.

[0113] Referring to step 1004, the UE sends an RRC recovery request message to gNB2, which includes an SDT indicator to indicate that SDT transmission is expected, in order to request the recovery of the inactive UE for SDT transmission.

[0114] Referring to step 1005, the UE is restored to an RRC inactive state at gNB2, and subsequent SDT data is sent / received between the UE and gNB2 via RACH or CG resources.

[0115] VII. An embodiment for sending DL SDTs triggered by NAS transmissions.

[0116] Figure 11 A non-limiting exemplary example is shown for initiating and transmitting a downlink (DL) SDT triggered by a NAS transmission. Referring to step 1100, UE 1191 is connected to the RAN in RRC inactive mode. The RAN may include gNB-DU 1192, gNB-CU-CP 1193, and gNB-CU-UP 1194 connected to the core network (CN, 1195).

[0117] Referring to step 1101, the CN may send a DOWNLINK NAS TRANSPORT message to request the transmission of a Non-Access Stratum (NAS) PDU to the UE, the message including the NAS PDU. The CN may also include in the message: a single NAS PDU indicator indicating that no subsequent NAS PDU transmission is expected; and / or a multiple NAS PDU indicator indicating that subsequent NAS PDU transmission is expected.

[0118] Referring to step 1102, after receiving one or more DOWNLINK NAS TRANSPORT messages from the CN, the gNB-CU-CP can decide to use SDT transmission for the UE. The gNB-CU-CP sends an F1 paging message to the gNB-DU to notify the DU to paging the corresponding UE for SDT transmission, and this message includes SDT information. The gNB-CU-CP can determine the items in the SDT information. When the gNB-CU-CP decides to use SDT transmission, the gNB-CU-CP may include an SDT indicator; when only one NAS PDU needs to be transmitted to the UE, the gNB-CU-CP may include a single packet indicator; and / or when multiple NAS PDUs need to be transmitted to the UE, the gNB-CU-CP may include a multi-packet indicator.

[0119] There are two options (or alternatives) for gNB-DU to transmit SDT information to UE: Option 1, gNB-DU includes SDT information in Paging Early Indication (PEI) message; and Option 2, gNB-DU includes SDT information in RRC paging message.

[0120] Regarding option 1 (1110), in step 1103a.1, after receiving the F1 paging message, the gNB-DU sends a PEI message to the UE before paging the UE. This PEI message includes SDT information indicating SDT transmission. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information may not need to include all SDT information received from the gNB-CU; for example, it may only include a portion of the received information, such as only the SDT indicator. In step 1103a.2, the gNB-DU sends an RRC paging message to the UE to page the corresponding UE.

[0121] Regarding option 2 (1120), in step 1103b, the gNB-DU sends an RRC paging message to the UE to page the corresponding UE for SDT transmission, the message including SDT information. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information here may not need to include all SDT information received from the gNB-CU; for example, it may only include a portion of the received information, such as only the SDT indicator.

[0122] In some implementations, after receiving an RRC paging message, when the UE receives SDT information from the RRC paging message and / or PEI message, the UE may decide to restore the inactive UE to perform SDT transmission.

[0123] In some implementations, when the UE is configured with reserved cell group (CG) resources and the UE receives a multi-packet indicator in the SDT information, the UE may prefer to use the reserved CG resources for SDT data transmission; and / or when the UE receives a single-packet indicator in the SDT information, the UE may prefer to use the random access channel (RACH) resources for SDT data transmission.

[0124] Referring to step 1104, the UE sends an RRC recovery request message to the gNB-DU, which includes an SDT indicator to indicate that SDT transmission is expected, in order to request the recovery of the inactive UE for SDT transmission.

[0125] Referring to step 1105, the UE is restored to an RRC inactive state at the gNB, and subsequent SDT data is sent / received between the UE and the gNB via RACH or CG resources.

[0126] VIII. Implementation of CN-triggered DL SDT sent via user plane

[0127] Figure 12 A non-limiting exemplary example of a downlink (DL) SDT initiated and transmitted by the CN via the user plane (UP) is shown. Referring to step 1200, UE 1291 is connected to the RAN in RRC inactive mode (i.e., the UE is in RRC inactive state). The RAN may include one or more gNB-DU 1292, one or more gNB-CU-CP 1293, and one or more gNB-CU-UP 1294 connected to the core network (CN, 1295).

[0128] Referring to step 1201, the gNB-CU-CP can send an RRC inactive transition report message to the CN to indicate that the UE is in an RRC inactive state. Therefore, the CN knows that the UE is in an RRC inactive state.

[0129] Referring to step 1202, when DL data arrives at the CN for a UE in an RRC inactive state, if the amount of arriving data is less than (or not greater than) the configured threshold, the CN decides to use SDT transmission. The CN sends an NG-U (User Plane of NG interface, where the interface is the interface between NG-RAN and 5GC) packet to gNB-CU-UP. The header of the first NG-U packet includes SDT information to request the UE to be restored for SDT transmission. The SDT information includes at least one of the following: an SDT indicator indicating that SDT transmission is expected; a single-packet indicator indicating that no subsequent SDT transmission is expected; or a multi-packet indicator indicating that subsequent SDT transmission is expected.

[0130] In some implementations, the CN can determine the items in the SDT information. When the CN decides to use SDT transmission, the CN may include an SDT indicator; when only one packet needs to be sent to the UE, the CN may include a single packet indicator; and / or when multiple packets need to be sent to the UE, the CN may include a multi-packet indicator.

[0131] Referring to step 1203, after receiving the SDT information in the NG-U packet header, gNB-CU-UP sends a DL DATA NOTIFICATION message to gNB-CU-CP to notify that DL data has arrived. This message includes SDT information to request the UE to resume SDT transmission. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information here may not need to include all SDT information received from the CN; for example, it may only include a portion of the received information, such as only the SDT indicator.

[0132] Optionally, in some implementations, gNB-CU-UP may include some received SDT data (for one or more PDCP PDUs configured with SDT) in the DL DATA NOTIFICATION message.

[0133] Referring to step 1204, after receiving one or more DL DATANOTIFICATION messages sent by gNB-CU-UP, when SDT information exists in the DL DATA NOTIFICATION message, gNB-CU-CP sends an F1 paging message to gNB-DU to notify the UE corresponding to the DU to perform SDT transmission. The F1 paging message includes SDT information. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no subsequent SDT transmission is expected; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information may not need to include all SDT information received from gNB-CU-UP; for example, it may only include a portion of the received information, such as only the SDT indicator.

[0134] Optionally, in some implementations, gNB-CU-CP may include some SDT data (for one or more PDCP PDUs configured with SDT) received from gNB-CU-UP via the DL DATA NOTIFICATION message in the F1 paging message.

[0135] There are two options (or alternatives) for gNB-DU to transmit SDT information to UE: Option 1, gNB-DU includes SDT information in Paging Early Indication (PEI) message; and Option 2, gNB-DU includes SDT information in RRC paging message.

[0136] Regarding option 1 (1210), in step 1205a.1, after receiving the F1 paging message, the gNB-DU sends a PEI message to the UE before paging the UE. This PEI message includes SDT information indicating SDT transmission. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information here may not need to include all SDT information received from the gNB-CU; for example, it may only include a portion of the received information, such as only the SDT indicator. In step 1205a.2, the gNB-DU sends an RRC paging message to the UE to page the corresponding UE.

[0137] Regarding option 2 (1220), in step 1205b, the gNB-DU sends an RRC paging message to the UE to page the corresponding UE for SDT transmission, the message including SDT information. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information here may not need to include all SDT information received from the gNB-CU; for example, it may only include a portion of the received information, such as only the SDT indicator.

[0138] In some implementations, after receiving an RRC paging message, when the UE receives SDT information from the RRC paging message and / or PEI message, the UE may decide to restore the inactive UE to perform SDT transmission.

[0139] In some implementations, when the UE is configured with reserved cell group (CG) resources and the UE receives a multi-packet indicator in the SDT information, the UE may prefer to use the reserved CG resources for SDT data transmission; and / or when the UE receives a single-packet indicator in the SDT information, the UE may prefer to use the random access channel (RACH) resources for SDT data transmission.

[0140] Referring to step 1206, the UE sends an RRC recovery request message to the gNB-DU, which includes an SDT indicator to indicate that SDT transmission is expected, in order to request the recovery of the inactive UE for SDT transmission.

[0141] Referring to step 1207, the UE is restored to an RRC inactive state at the gNB, and subsequent SDT data is sent / received between the UE and the gNB via RACH or CG resources.

[0142] IX. Implementation of DL SDT triggered by CN transmitted via control plane

[0143] Figure 13 A non-limiting exemplary example is shown of a downlink (DL) SDT initiated and transmitted by the CN via the control plane (CP). Referring to step 1300, UE 1391 is connected to the RAN in RRC inactive mode (i.e., the UE is in RRC inactive state). The RAN may include one or more gNB-DU 1392, one or more gNB-CU-CP 1393, and one or more gNB-CU-UP 1394 connected to the core network (CN, 1395).

[0144] Referring to step 1301, the gNB-CU-CP can send an RRC inactive transition report message to the CN to indicate that the UE is in an RRC inactive state. Therefore, the CN knows that the UE is in an RRC inactive state.

[0145] Referring to step 1302, when DL data arrives at the CN for a UE in an RRC inactive state, if the amount of arriving data is less than (or not greater than) a configured threshold, the CN decides to use SDT transmission. The CN sends an NG Application Protocol (NGAP) message, such as SDT DATA NOTIFICATION, to the gNB-CU-CP to notify that DLSDT data has arrived. This message includes SDT information to request the UE to resume SDT transmission. The SDT information includes at least one of the following: an SDT indicator indicating that SDT transmission is expected; a single-packet indicator indicating that no subsequent SDT transmission is expected; and a multi-packet indicator indicating that subsequent SDT transmission is expected. In some implementations, the CN may determine the items in the SDT information. When the CN decides to use SDT transmission, the CN may include an SDT indicator; when only one packet needs to be sent to the UE, the CN may include a single-packet indicator; and / or when multiple packets need to be sent to the UE, the CN may include a multi-packet indicator.

[0146] Referring to step 1303, when there are multiple packets that need to be sent to the UE, the CN can send subsequent SDT data to the gNB CU UP via one or more NG-U packets.

[0147] Referring to step 1304, after gNB-CU-UP receives the NG-U packet sent by CN, gNB-CU-UP sends a DL DATA NOTIFICATION message to gNB-CU-CP to notify that data has arrived for the UE.

[0148] Referring to step 1305, after receiving one or more DL DATANOTIFICATION messages sent by gNB-CU-UP, when SDT information exists in the DL DATA NOTIFICATION message, gNB-CU-CP sends an F1 paging message to gNB-DU to notify the UE corresponding to the DU to perform SDT transmission. The F1 paging message includes SDT information. SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information may not need to include all SDT information received from the CN; for example, it may only include a portion of the received information, such as only the SDT indicator.

[0149] There are two options (or alternatives) for gNB-DU to transmit SDT information to UE: Option 1, gNB-DU includes SDT information in Paging Early Indication (PEI) message; and Option 2, gNB-DU includes SDT information in RRC paging message.

[0150] Regarding option 1 (1310), in step 1306a.1, after receiving the F1 paging message, the gNB-DU sends a PEI message to the UE before paging the UE. This PEI message includes SDT information indicating SDT transmission. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information may not need to include all SDT information received from the gNB-CU; for example, it may only include a portion of the received information, such as only the SDT indicator. In step 1306a.2, the gNB-DU sends an RRC paging message to the UE to page the corresponding UE.

[0151] Regarding option 2 (1320), in step 1306b, the gNB-DU sends an RRC paging message to the UE to page the corresponding UE for SDT transmission, the message including SDT information. The SDT information includes at least one of the following: an SDT indicator indicating expected SDT transmission; a single-packet indicator indicating no expected subsequent SDT transmission; or a multi-packet indicator indicating expected subsequent SDT transmission. In some implementations, the SDT information here may not need to include all SDT information received from the gNB-CU; for example, it may only include a portion of the received information, such as only the SDT indicator.

[0152] In some implementations, after receiving an RRC paging message, when the UE receives SDT information from the RRC paging message and / or PEI message, the UE may decide to restore the inactive UE to perform SDT transmission.

[0153] In some implementations, when the UE is configured with reserved cell group (CG) resources and the UE receives a multi-packet indicator in the SDT information, the UE may prefer to use the reserved CG resources for SDT data transmission; and / or when the UE receives a single-packet indicator in the SDT information, the UE may prefer to use the random access channel (RACH) resources for SDT data transmission.

[0154] Referring to step 1307, the UE sends an RRC recovery request message to the gNB-DU, which includes an SDT indicator to indicate that SDT transmission is expected, in order to request the recovery of the inactive UE for SDT transmission.

[0155] Referring to step 1308, the UE is restored to an RRC inactive state at the gNB, and subsequent SDT data is sent / received between the UE and the gNB via RACH or CG resources.

[0156] This disclosure describes methods, apparatus, and computer-readable media for wireless communication. This disclosure addresses the issue of configuring small data transmission. The methods, apparatus, and computer-readable media described in this disclosure can improve the performance of wireless communication by configuring small data transmission, thereby improving efficiency and overall performance. The methods, apparatus, and computer-readable media described in this disclosure can improve the overall efficiency of wireless communication systems.

[0157] Throughout this specification, references to features, advantages, or similar language do not imply that all features and advantages achievable with this solution should be or should be included in any single implementation of this solution. Rather, references to features and advantages are to be understood as indicating that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of this solution. Therefore, throughout this specification, discussions of features and advantages, as well as similar language, may, but do not necessarily, refer to the same embodiment.

[0158] Furthermore, in one or more embodiments, the described features, advantages, and characteristics of this solution can be combined in any suitable manner. Those skilled in the art will recognize that, based on the description herein, this solution can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of this solution.

Claims

1. A wireless communication method, comprising: A paging message is sent from a first network node to a second network node. The paging message is configured to request the second network node to page the user equipment (UE) for Small Data Transmission (SDT) transmission, wherein: The paging message includes SDT information, and The paging message is configured to request the second network node to page the UE according to the SDT information in order to perform the SDT transmission; In response to a Radio Resource Control (RRC) paging message being sent to the UE, an RRC recovery request message is received from the UE by the second network node. The RRC recovery request message includes an SDT indicator to request the UE, which is in an inactive state, to resume the SDT transmission.

2. The method according to claim 1, wherein: The first network node is the base station's control unit gNB-CU, and the second network node is the base station's distributed unit gNB-DU; or The first network node is the first gNB, and the second network node is the second gNB.

3. The method according to any one of claims 1 to 2, wherein: The first network node is gNB-CU; The control plane entity gNB-CU-CP of the gNB-CU sends a message to the user plane entity gNB-CU-UP of the gNB-CU, the message including SDT trigger parameters; and The SDT triggering parameters include a data volume threshold for the UE.

4. The method according to any one of claims 1 to 2, wherein: The SDT information includes an SDT indicator that indicates that the SDT transmission is expected.

5. A method for wireless communication, comprising: The second network node receives a paging message from the first network node. The paging message is configured to request the second network node to page the user equipment (UE) for Small Data Transmission (SDT) transmission. The paging message includes SDT information. The second network node pages the UE according to the SDT information to perform the SDT transmission; and In response to sending a Radio Resource Control (RRC) paging message to the UE, the second network node receives an RRC recovery request message from the UE, the RRC recovery request message including an SDT indicator to request the recovery of the UE, which is in an inactive state, to perform the SDT transmission.

6. The method according to claim 5, wherein: The first network node is the base station's control unit gNB-CU, and the second network node is the base station's distributed unit gNB-DU; or The first network node is the first gNB, and the second network node is the second gNB.

7. The method according to claim 5, wherein: The SDT information includes an SDT indicator that indicates that the SDT transmission is expected.

8. A method for wireless communication, comprising: The user equipment (UE) receives a Radio Resource Control (RRC) paging message from the network node; In response to the RRC paging message including Small Data Transmission Deployment (SDT) information, the UE performs the SDT procedure in the following manner: The UE sends an RRC recovery request message to the network node. The RRC recovery request message includes an SDT indicator to request the recovery of the UE, which is in an inactive state, to perform the SDT transmission.

9. The method according to claim 8, wherein: The SDT information includes an SDT indicator that indicates that the SDT transmission is expected.

10. The method according to claim 8, wherein: The network node is one of the distributed units (gNB-DU) of a base station or gNB.

11. A network node, comprising: A memory that stores instructions; as well as At least one processor communicating with the memory, wherein, when the at least one processor executes the instruction, the at least one processor is configured to cause the network node to execute: The system receives a paging message from another network node, the paging message being configured to request the network node to page the user equipment (UE) for Small Data Transmission (SDT) transmission, wherein the paging message includes SDT information. Page the UE according to the SDT information to perform the SDT transmission; and In response to sending a Radio Resource Control (RRC) paging message to the UE, an RRC recovery request message is received from the UE, the RRC recovery request message including an SDT indicator to request the recovery of the UE, which is in an inactive state, to perform the SDT transmission.

12. The network node according to claim 11, wherein: The other network node is the base station's control unit gNB-CU, and the network node is the base station's distributed unit gNB-DU; or The other network node is the first gNB, and the network node is the second gNB.

13. The network node according to claim 11, wherein: The SDT information includes an SDT indicator that indicates that the SDT transmission is expected.

14. A device for wireless communication, comprising: A memory that stores instructions; as well as At least one processor communicating with the memory, wherein, when the at least one processor executes the instructions, the at least one processor is configured to cause the device to perform: Receive Radio Resource Control (RRC) paging messages from network nodes; In response to the RRC paging message including Small Data Transmission Deployment (SDT) information, the SDT procedure is performed as follows: An RRC recovery request message is sent to the network node, the RRC recovery request message including an SDT indicator to request the recovery of the inactive device for the SDT transmission.

15. The device according to claim 14, wherein: The SDT information includes an SDT indicator that indicates that the SDT transmission is expected.

16. The device according to claim 14, wherein: The network node is one of the distributed units (gNB-DU) of a base station or gNB.

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