Method and apparatus for mobile terminated small data transmission (MT-SDT)

Abstract

A method of wireless communication at a network node and a related apparatus are provided. In the method, the network node first transmits a paging message comprising a first indication of mobile terminated small data transmission (MT-SDT) for a user equipment (UE) in a radio resource control (RRC) inactive state, and transmits data to the UE for transmission while the UE remains in the RRC inactive state. By providing data transmission for UEs in an idle or inactive state, power consumption, latency, and system overhead may advantageously be reduced.

Description

Technical Field

[0001] The present disclosure relates generally to communication systems, and more particularly to methods and apparatus for Mobile Terminated Small Data Transmission (MT-SDT). Background Art

[0002] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0003] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continuous mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)) and other requirements. 5GNR includes services associated with enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC). Certain aspects of 5G NR may be based on 4G Long Term Evolution (LTE) standards. It is necessary to further improve 5G NR technology. In addition, these improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the invention

[0004] A simplified summary of one or more aspects is presented below to provide a basic understanding of these aspects. This summary is not an extensive review of all contemplated aspects. This summary neither identifies the key or important elements of all aspects, nor describes the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description presented later.

[0005] In one aspect of the present disclosure, a method for wireless communication at a network node, a related computer readable medium, and a related device are provided. The device transmits a paging message including a first indication of a mobile terminated small data transmission (MT-SDT) for a user equipment (UE) in a radio resource control (RRC) inactive state; and when the UE remains in the RRC inactive state, transmits data to the UE for transmission.

[0006] In one aspect of the present disclosure, a method for wireless communication at a UE, a related computer-readable medium, and a related device are provided. The device receives a paging message from a network node, the paging message including a first indication of an MT-SDT for the UE when the UE is in an RRC inactive state. The device sends a message including a second indication for the MT-SDT to the network node, and when the UE remains in the RRC inactive state, receives downlink data from the network node.

[0007] To achieve the aforementioned and related purposes, one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail some exemplary features of one or more aspects. However, these features indicate only some of the various ways in which the principles of the various aspects can be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0009] Figure 2A is a diagram illustrating an example of a first frame according to various aspects of the present disclosure.

[0010] Figure 2B is a diagram illustrating an example of DL channels within a subframe according to various aspects of the present disclosure.

[0011] Figure 2C is a diagram illustrating an example of a second frame according to various aspects of the present disclosure.

[0012] Figure 2D is a diagram illustrating an example of UL channels within a subframe according to various aspects of the present disclosure.

[0013] Figure 3 is a diagram illustrating an example of a base station (BS) and a user equipment (UE) in an access network.

[0014] Figure 4 is a call flow diagram illustrating a MT-SDT indication procedure through paging according to various aspects of the present disclosure.

[0015] Figure 5 is a call flow diagram illustrating an MT-SDT indication procedure performed by a UE according to various aspects of the present disclosure.

[0016] Figure 6 is a call flow diagram illustrating a NG-RAN determination procedure for paging a UE for MT-SDT according to various aspects of the present disclosure.

[0017] Fig. 7A and Figure 7B is a call flow diagram illustrating MT-SDT with dual connectivity according to various aspects of the present disclosure.

[0018] Figure 8 is a call flow diagram illustrating a MT-SDT indication procedure by a retrieve UE context request according to various aspects of the present disclosure.

[0019] Fig. 9 , Fig.10 , Fig.11 and Fig.12 is a flow chart illustrating a method of wireless communication according to various aspects of the present disclosure.

[0020] Fig.13 , Fig.14 and Fig.15 is a diagram illustrating a hardware implementation of a system of MT-SDT according to various aspects of the present disclosure. DETAILED DESCRIPTION

[0021] The network may have data to send to a UE that is in the RRC Inactive state.

[0022] The specific embodiments described below in conjunction with the accompanying drawings are descriptions of various configurations and do not represent the only configurations in which the concepts described herein can be practiced. In order to provide a thorough understanding of the various concepts, the specific embodiments include specific details. However, these concepts can be practiced without these specific details. In some cases, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0023] Several aspects of telecommunication systems are presented with reference to various apparatuses and methods. These apparatuses and methods are described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether these elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0024] As an example, an element, or any part of an element, or any combination of elements can be implemented as a "processing system", which includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic components, discrete hardware circuits, and other suitable hardware configured to perform various functionalities described throughout the present disclosure. One or more processors in a processing system can execute software. Whether referred to as software, firmware, middleware, microcode, hardware description language, or other terms, software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, or any combination thereof.

[0025] Thus, in one or more example aspects, specific implementations and / or use cases, the described functionality may be implemented in hardware, software, or any combination thereof. If implemented in software, the functionality may be stored or encoded as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media. Storage media may be any available media that can be accessed by a computer. As an example, such computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of these types of computer-readable media, or any other medium that can be used to store computer-executable code in the form of instructions or data structures that can be accessed by a computer.

[0026] Although various aspects, specific implementations and / or use cases are described in this application by the illustration of some examples, additional or different aspects, specific implementations and use cases may be generated in many different arrangements and scenarios. The various aspects, specific implementations and / or use cases described herein can be implemented across many different platform types, devices, systems, shapes, sizes and packaging arrangements. For example, various aspects, specific implementations and / or use cases can be generated via integrated chip specific implementations and other devices based on non-module components (e.g., end-user devices, vehicles, communication equipment, computing equipment, industrial equipment, retail / purchase equipment, medical equipment, devices that enable artificial intelligence (AI), etc.). Although some examples may or may not be specifically for use cases or applications, the described examples may have wide applicability. Various aspects, specific implementations and / or use cases can be in the range from chip-level or modular components to non-modular, non-chip-level specific implementations, and further to the range of aggregated, distributed or original equipment manufacturer (OEM) equipment or systems in conjunction with one or more technologies herein. In some actual settings, the equipment combined with the various aspects and features described may also include additional components and features for implementing and practicing the claimed and described aspects. For example, the transmission and reception of wireless signals necessarily include multiple components for analog and digital purposes (e.g., hardware components including antennas, RF chains, power amplifiers, modulators, buffers, processors, interleavers, adders / summers, etc.) The various techniques described herein can be practiced in a wide variety of devices of various sizes, shapes, and configurations, chip-level components, systems, distributed arrangements, aggregated or disaggregated components, end-user devices, etc.

[0027] The deployment of a communication system (such as a 5G NR system) can be arranged with various components or constituent parts in a variety of ways. In a 5G NR system or network, a network node, a network entity, a mobility element of a network, a radio access network (RAN) node, a core network node, a network element or a network equipment (such as a base station (BS), or one or more units (or one or more components) that perform base station functionality can be implemented in an aggregated or decomposed architecture. For example, a BS (such as a Node B (NB), an evolved NB (eNB), an NR BS, a 5G NB, an access point (AP), a transmit receive point (TRP) or a cell, etc.) can be implemented as an aggregated base station (also referred to as an independent BS or a monolithic BS) or a decomposed base station.

[0028] A converged base station may be configured to utilize a radio protocol stack physically or logically integrated within a single RAN node. A decomposed base station may be configured to utilize a protocol stack physically or logically distributed between two or more units, such as one or more central or centralized units (CUs), one or more distributed units (DUs), or one or more radio units (RUs). In some aspects, a CU may be implemented within a RAN node, and one or more DUs may be co-located with the CU, or alternatively, may be geographically or virtually distributed in one or more other RAN nodes. A DU may be implemented to communicate with one or more RUs. Each of a CU, a DU, and a RU may be implemented as a virtual unit, i.e., a virtual central unit (VCU), a virtual distributed unit (VDU), or a virtual radio unit (VRU).

[0029] Base station operation or network design may take into account the aggregated nature of base station functionality. For example, a disaggregated base station may be used in an integrated access backhaul (IAB) network, an open radio access network (O-RAN (network configuration such as that initiated by the O-RAN Alliance)), or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN)). Decomposition may include distributing functionality across two or more units at various physical locations, as well as virtually distributing functionality of at least one unit, which may enable flexibility in network design. Individual units of a disaggregated base station or disaggregated RAN architecture may be configured for wired or wireless communication with at least one other unit.

[0030] Figure 1 1 is a diagram 100 illustrating an example of a wireless communication system and an access network. The illustrated wireless communication system includes a disaggregated base station architecture. The disaggregated base station architecture may include one or more CUs 110 that may communicate directly with a core network 120 via a backhaul link, or indirectly with the core network 120 through one or more disaggregated base station units, such as a near real-time (near RT) RAN intelligent controller (RIC) 125 via an E2 link, or a non-real-time (non-RT) RIC 115 associated with a service management and orchestration (SMO) framework 105, or both. The CU 110 may communicate with one or more DUs 130 via corresponding midhaul links, such as an F1 interface. The DU 130 may communicate with one or more RUs 140 via corresponding fronthaul links. The RU 140 may communicate with corresponding UEs 104 via one or more radio frequency (RF) access links. In some implementations, a UE 104 may be served simultaneously by multiple RUs 140.

[0031] Each of the units (i.e., CU 110, DU 130, RU 140, and near-RT RIC 125, non-RT RIC 115, and SMO framework 105) may include or be coupled to one or more interfaces configured to receive or send signals, data, or information (collectively referred to as signals) via a wired or wireless transmission medium. Each of these units or an associated processor or controller that provides instructions to the communication interface of these units may be configured to communicate with one or more of the other units via a transmission medium. For example, these units may include a wired interface configured to receive signals or send signals to one or more of the other units via a wired transmission medium. Additionally, these units may include a wireless interface that may include a receiver, transmitter, or transceiver (such as an RF transceiver) configured to receive and / or send signals to one or more of the other units via a wireless transmission medium.

[0032] In some aspects, CU 110 may host one or more higher layer control functions. Such control functions may include radio resource control (RRC), packet data convergence protocol (PDCP), service data adaptation protocol (SDAP), etc. Each control function may be implemented using an interface that is configured to communicate signals with other control functions hosted by CU 110. CU 110 may be configured to handle user plane functionality (i.e., central unit-user plane (CU-UP)), control plane functionality (i.e., central unit-control plane (CU-CP)), or a combination thereof. In some specific implementations, CU 110 may be logically split into one or more CU-UP units and one or more CU-CP units. When implemented in an O-RAN configuration, the CU-UP unit may communicate bidirectionally with the CU-CP unit via an interface (such as an E1 interface). As needed, CU 110 may be implemented to communicate with DU 130 for network control and signaling.

[0033] DU 130 may correspond to a logical unit that includes one or more base station functions for controlling the operation of one or more RUs 140. In some aspects, DU 130 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, etc.) at least in part according to a functional split such as those defined by 3GPP. In some aspects, DU 130 may also host one or more low PHY layers. Each layer (or module) may be implemented using an interface that is configured to communicate signals with other layers (and modules) hosted by DU 130 or with control functions hosted by CU 110.

[0034] The lower layer functionality may be implemented by one or more RUs 140. In some deployments, the RU 140 controlled by the DU 130 may correspond to a logical node that hosts RF processing functions, or low PHY layer functions (such as performing Fast Fourier Transform (FFT), Inverse FFT (iFFT), digital beamforming, physical random access channel (PRACH) extraction and filtering, etc.), or both, based at least in part on functional splitting (such as lower layer functional splitting). In such an architecture, the RU 140 may be implemented to handle over-the-air (OTA) communications with one or more UEs 104. In some specific implementations, real-time and non-real-time aspects of control plane and user plane communications with the RU 140 may be controlled by the corresponding DU 130. In some scenarios, this configuration may enable the implementation of the DU 130 and the CU 110 in a cloud-based RAN architecture (such as a vRAN architecture).

[0035] The SMO framework 105 may be configured to support RAN deployment and provisioning of non-virtualized network elements and virtualized network elements. For non-virtualized network elements, the SMO framework 105 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements, which may be managed via an operation and maintenance interface (such as an O1 interface). For virtualized network elements, the SMO framework 105 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) 190) to perform network element lifecycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface (such as an O2 interface). Such virtualized network elements may include, but are not limited to, CU 110, DU 130, RU 140, and near-RT RIC 125. In some specific implementations, the SMO framework 105 may communicate with hardware aspects of the 4G RAN (such as an open eNB (O-eNB) 111) via the O1 interface. Additionally, in some specific implementations, the SMO framework 105 may communicate directly with one or more RUs 140 via the O1 interface. The SMO framework 105 may also include a non-RT RIC 115 configured to support the functionality of the SMO framework 105 .

[0036] The non-RT RIC 115 may be configured to include logic functions that enable non-real-time control and optimization of RAN elements and resources, artificial intelligence (AI) / machine learning (ML) (AI / ML) workflows including model training and updating, or policy-based guidance of applications / features in the near-RT RIC 125. The non-RT RIC 115 may be coupled to or communicate with the near-RT RIC 125 (such as via an A1 interface). The near-RT RIC 125 may be configured to include logic functions that enable near-real-time control and optimization of RAN elements and resources via data collection and actions through an interface (such as via an E2 interface) that connects one or more CUs 110, one or more DUs 130, or both, and the O-eNB with the near-RT RIC 125.

[0037] In some implementations, in order to generate an AI / ML model to be deployed in the near-RT RIC 125, the non-RT RIC 115 may receive parameters or external enrichment information from an external server. Such information may be utilized by the near-RT RIC 125 and may be received from a non-network data source or from a network function at the SMO framework 105 or the non-RT RIC 115. In some examples, the non-RT RIC 115 or the near-RT RIC 125 may be configured to tune RAN behavior or performance. For example, the non-RT RIC 115 may monitor long-term trends and patterns of performance and employ AI / ML models to perform corrective actions through the SMO framework 105 (such as via reconfiguration of O1) or via the creation of RAN management policies (such as A1 policies).

[0038] At least one of the CU 110, the DU 130, and the RU 140 may be referred to as a base station 102. Therefore, the base station 102 may include one or more of the CU 110, the DU 130, and the RU 140 (each component is indicated by a dotted line to indicate that each component may be included in the base station 102 or may not be included in the base station). The base station 102 provides an access point to the core network 120 for the UE 104. The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). Small cells include femto cells, pico cells, and micro cells. A network including both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may provide services to a restricted group referred to as a closed subscriber group (CSG). The communication link between RU 140 and UE 104 may include uplink (UL) (also known as reverse link) transmission from UE 104 to RU 140 and / or downlink (DL) (also known as forward link) transmission from RU 140 to UE 104. The communication link may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming and / or transmit diversity. The communication link may be through one or more carriers. For each carrier allocated in a carrier aggregation of up to Yx MHz (x component carriers) for transmission in each direction, the base station 102 / UE 104 may use a spectrum of up to Y MHz (e.g., 5MHz, 10MHz, 15MHz, 20MHz, 100MHz, 400MHz, etc.) bandwidth. These carriers may or may not be adjacent to each other. The allocation of carriers may be equivalent to DL and UL asymmetric (e.g., more or fewer carriers may be allocated to DL than to UL). Component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell) and the secondary component carrier may be referred to as a secondary cell (SCell).

[0039] Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL wireless wide area network (WWAN) spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). The D2D communication may be through a variety of wireless D2D communication systems, such as, for example, Bluetooth, Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, LTE, or NR.

[0040] The wireless communication system may also include a Wi-Fi AP 150 that communicates with a UE 104 (also referred to as a Wi-Fi station (STA)) via a communication link 154, for example, in a 5 GHz unlicensed spectrum, etc. When communicating in an unlicensed spectrum, the UE 104 / AP 150 may perform a clear channel assessment (CCA) to determine whether a channel is available prior to communication.

[0041] The electromagnetic spectrum is typically subdivided into various categories, bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating bands have been identified as frequency range designations FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). Although a portion of FR1 is greater than 6 GHz, FR1 is often referred to (interchangeably) as the "sub-6 GHz" band in various documents and articles. A similar naming issue sometimes occurs with respect to FR2, which is often (interchangeably) referred to as the "millimeter wave" band in documents and articles, although it is different from the extremely high frequency (EHF) band (30 GHz–300 GHz) that is identified as the "millimeter wave" band by the International Telecommunication Union (ITU).

[0042] Frequencies between FR1 and FR2 are generally referred to as mid-band frequencies. Recent 5G NR research has identified the operating bands for these mid-band frequencies as frequency range designation FR3 (7.125GHz–24.25GHz). The bands falling within FR3 can inherit FR1 characteristics and / or FR2 characteristics, and thus the features of FR1 and / or FR2 can be effectively extended to mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operations to more than 52.6GHz. For example, three higher operating bands have been identified as frequency range designations FR2-2 (52.6GHz-71GHz), FR4 (71GHz-114.25GHz), and FR5 (114.25GHz-300GHz). Each of these higher frequency bands falls within the EHF band.

[0043] In view of the above, unless otherwise specified, if the term "6 GHz or less" is used herein, it may broadly refer to frequencies that may be less than 6 GHz, may be within FR1, or may include mid-band frequencies. In addition, unless otherwise specified, if the term "millimeter wave" is used herein, it may broadly refer to frequencies that may include mid-band frequencies, may be within FR2, FR4, FR2-2, and / or FR5, or may be within the EHF band.

[0044] The base station 102 and the UE 104 may each include multiple antennas (such as antenna elements, antenna panels, and / or antenna arrays) to facilitate beamforming. The base station 102 may send a beamformed signal 182 to the UE 104 in one or more transmit directions. The UE 104 may receive the beamformed signal from the base station 102 in one or more receive directions. The UE 104 may also send a beamformed signal 184 to the base station 102 in one or more transmit directions. The base station 102 may receive the beamformed signal from the UE 104 in one or more receive directions. The base station 102 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of the base station 102 / UE 104. The transmit direction and receive direction of the base station 102 may be the same or different. The transmit direction and receive direction of the UE 104 may be the same or different.

[0045] The base station 102 may include and / or be referred to as a gNB, a Node B, an eNB, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit receive point (TRP), a network node, a network entity, a network equipment, or some other suitable term. The base station 102 may be implemented as an integrated access and backhaul (IAB) node, a relay node, a sidelink node, an aggregated (monolithic) base station with a baseband unit (BBU) (including a CU and a DU) and a RU, or as a decomposed base station including one or more of a CU, a DU, and / or a RU. A set of base stations that may include decomposed base stations and / or aggregated base stations may be referred to as a next generation (NG) RAN (NG-RAN).

[0046] The core network 120 may include an access and mobility management function (AMF) 161, a session management function (SMF) 162, a user plane function (UPF) 163, a unified data management (UDM) 164, one or more location servers 168, and other functional entities. AMF 161 is a control node that processes signaling between UE 104 and the core network 120. AMF 161 supports registration management, connection management, mobility management, and other functions. SMF 162 supports session management and other functions. UPF 163 supports packet routing, packet forwarding, and other functions. UDM 164 supports the generation of authentication and key agreement (AKA) credentials, user identity handling, access authorization, and subscription management. One or more location servers 168 are illustrated as including a gateway mobile location center (GMLC) 165 and a location management function (LMF) 166. However, in general, the one or more location servers 168 may include one or more location / positioning servers, which may include one or more of the GMLC 165, LMF 166, position determination entity (PDE), serving mobile location center (SMLC), mobile positioning center (MPC), etc. GMLC 165 and LMF 166 support UE location services. GMLC 165 provides an interface for clients / applications (e.g., emergency services) to access UE positioning information. LMF 166 receives measurement and assistance information from NG-RAN and UE 104 via AMF 161 to calculate the location of UE 104. NG-RAN may determine the location of UE 104 using one or more positioning methods. Positioning UE 104 may involve signal measurements, position estimation, and optional speed calculation based on these measurements. Signal measurements may be performed by UE 104 and / or serving base station 102. The measured signals may be based on a satellite positioning system (SPS) 170 (e.g., one or more of a global navigation satellite system (GNSS), a global positioning system (GPS), a non-terrestrial network (NTN), or other satellite positioning / positioning systems), LTE signals, wireless local area network (WLAN) signals, Bluetooth signals, a terrestrial beacon system (TBS), sensor-based information (e.g., an atmospheric pressure sensor, a motion sensor), an NR enhanced cell ID (NR E-CID) method, NR signals (e.g., multi-round trip time (multi-RTT), DL angle of departure (DL-AoD), DL time difference of arrival (DL-TDOA), UL time difference of arrival (UL-TDOA), and UL angle of arrival (UL-AoA) positioning), and / or one or more of other systems / signals / sensors.

[0047] Examples of UE 104 include cellular phones, smart phones, session initiation protocol (SIP) phones, laptops, personal digital assistants (PDAs), satellite radios, global positioning systems, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablet computers, smart devices, wearable devices, vehicles, electric meters, gas pumps, large or small kitchen appliances, healthcare equipment, implants, sensors / actuators, displays, or any other similarly functional devices. Some of the UEs 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, toasters, vehicles, heart monitors, etc.). UE 104 may also be referred to as stations, mobile stations, subscriber stations, mobile units, subscriber units, wireless units, remote units, mobile devices, wireless devices, wireless communication devices, remote devices, mobile subscriber stations, access terminals, mobile terminals, wireless terminals, remote terminals, mobile phones, user agents, mobile clients, clients, or some other suitable terminology. In some scenarios, the term UE may also be applied to one or more supporting devices, such as in a device cluster arrangement. One or more of these devices may access the network collectively and / or individually.

[0048] Reference again Figure 1 In some aspects, the UE 104 may be configured to include an MT-SDT component 198 configured to: receive a paging message from a network node, the paging message including a first indication of an MT-SDT for the UE when the UE is in an RRC inactive state; send a message including a second indication of the MT-SDT to the network node; and receive downlink data from the network node while the UE remains in the RRC inactive state. In some aspects, the base station 102 may be configured to include an MT-SDT generation component 199 configured to: transmit a paging message including a first indication of an MT-SDT for the UE in the RRC inactive state; and transmit data to the UE for transmission while the UE remains in the RRC inactive state. Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar fields, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0049] Figure 2A FIG200 is a diagram illustrating an example of a first subframe within a 5G NR frame structure. Figure 2B FIG230 is a diagram illustrating an example of DL channels within a 5G NR subframe. Figure 2C FIG250 is a diagram illustrating an example of a second subframe within a 5G NR frame structure. Figure 2DFIG280 is a diagram illustrating an example of UL channels within a 5G NR subframe. The 5G NR frame structure may be frequency division duplex (FDD), where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to either DL or UL, or may be time division duplex (TDD), where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to both DL and UL. Figure 2A , Figure 2C In the example provided, the 5G NR frame structure is assumed to be TDD, where subframe 4 is configured with slot format 28 (most of which are DL), where D is DL, U is UL, and F is flexible between DL / UL, and subframe 3 is configured with slot format 1 (all of which are UL). Although subframes 3 and 4 are shown as having slot formats 1 and 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0 and 1 are full DL and full UL, respectively. Other slot formats 2-61 include a mix of DL, UL and flexible symbols. The UE is configured with the slot format through the received slot format indicator (SFI) (dynamically configured through DL control information (DCI) or semi-statically / statically configured through radio resource control (RRC) signaling). Note that the following description also applies to the 5G NR frame structure as TDD.

[0050] FIG. 2A to FIG. 2D The frame structure is illustrated, and various aspects of the present disclosure may be applicable to other wireless communication technologies that may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 subframes of equal size (1ms). Each subframe may include one or more time slots. A subframe may also include a microslot, which may include 7, 4 or 2 symbols. Each time slot may include 14 or 12 symbols, depending on whether the cyclic prefix (CP) is normal or extended. For a normal CP, each time slot may include 14 symbols, and for an extended CP, each time slot may include 12 symbols. The symbol on the DL may be a CP orthogonal frequency division multiplexing (OFDM) (CP-OFDM) symbol. The symbol on the UL may be a CP-OFDM symbol (for high throughput scenarios) or a discrete Fourier transform (DFT) extended OFDM (DFT-s-OFDM) symbol (also known as a single carrier frequency division multiple access (SC-FDMA) symbol) (for power-limited scenarios; limited to single-stream transmission). The number of slots within a subframe is based on the CP and the parameter set. The parameter set defines the subcarrier spacing (SCS) and effectively defines the symbol length / duration, which is equal to 1 / SCS.

[0051]

[0052] For normal CP (14 symbols / slot), different parameter sets μ0 to 4 allow 1, 2, 4, 8, and 16 slots per subframe, respectively. For extended CP, parameter set 2 allows 4 slots per subframe. Thus, for normal CP and parameter set μ, there are 14 symbols / slot and 2 μ timeslots / subframe. The subcarrier spacing can be equal to 2 μ *15kHz, where μ is parameter set 0 to 4. Therefore, the subcarrier spacing for parameter set μ=0 is 15kHz, and the subcarrier spacing for parameter set μ=4 is 240kHz. The symbol length / duration is inversely related to the subcarrier spacing. FIG. 2A to FIG. 2D An example is provided for a normal CP with 14 symbols per slot and a parameter set μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is about 16.67 μs. Within a frame set, there may be one or more different bandwidth parts (BWPs) that are frequency-division multiplexed (see Figure 2B ). Each BWP may have a specific parameter set and CP (normal or extended).

[0053] A resource grid may be used to represent the frame structure. Each slot includes a resource block (RB) (also referred to as a physical RB (PRB)) extending over 12 consecutive subcarriers. The resource grid is divided into a plurality of resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0054] like Figure 2A As illustrated, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include a demodulation RS (DM-RS) (indicated as R for one particular configuration, but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS) for channel estimation at the UE. The RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0055] Figure 2BExamples of various DL channels within a subframe of a frame are illustrated. A physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs) (e.g., 1, 2, 4, 8, or 16 CCEs), each CCE including six RE groups (REGs), each REG including 12 consecutive REs in an OFDM symbol of an RB. A PDCCH within a BWP may be referred to as a control resource set (CORESET). The UE is configured to monitor PDCCH candidates in a PDCCH search space (e.g., a common search space, a UE-specific search space) during a PDCCH monitoring opportunity on a CORESET, wherein the PDCCH candidates have different DCI formats and different aggregation levels. Additional BWPs may be located at higher and / or lower frequencies on the channel bandwidth. A primary synchronization signal (PSS) may be within symbol 2 of a particular subframe of a frame. The PSS is used by UE 104 to determine subframe / symbol timing and physical layer identification. A secondary synchronization signal (SSS) may be within symbol 4 of a particular subframe of a frame. The SSS is used by the UE to determine the physical layer cell identity group number and the radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine the physical cell identifier (PCI). Based on the PCI, the UE can determine the location of the DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) can be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block (also referred to as an SS block (SSB)). The MIB provides the number of RBs in the system bandwidth and the system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not sent via the PBCH (such as a system information block (SIB)), and paging messages.

[0056] like Figure 2C As illustrated, some of the REs carry DM-RS (indicated as R for a particular configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may send DM-RS for a physical uplink control channel (PUCCH) and DM-RS for a physical uplink shared channel (PUSCH). The PUSCH DM-RS may be sent in the first or first two symbols of the PUSCH. Depending on whether a short PUCCH or a long PUCCH is sent and depending on the specific PUCCH format used, the PUCCH DM-RS may be sent in different configurations. The UE may send a sounding reference signal (SRS). The SRS may be sent in the last symbol of a subframe. The SRS may have a comb structure, and the UE may send the SRS on one of the teeth of the comb. The SRS may be used by the base station for channel quality estimation to achieve frequency-dependent scheduling of the UL.

[0057] Figure 2DExamples of various UL channels within a subframe of a frame are illustrated. The PUCCH may be located at a position as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicators (CQI), precoding matrix indicators (PMI), rank indicators (RI), and hybrid automatic repeat request (HARQ) acknowledgement (ACK) (HARQ-ACK) feedback (i.e., one or more HARQ ACK bits indicating one or more ACKs and / or negative ACKs (NACKs)). The PUSCH carries data and may be used to carry, among other things, a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0058] Figure 3 375. The Controller / Processor 375 is a block diagram of a base station 310 in an access network communicating with a UE 350. In the DL, Internet Protocol (IP) packets may be provided to a controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller / processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with transfer of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0059] The transmit (TX) processor 316 and receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1 (which includes the physical (PHY) layer) may include error detection on the transport channel, forward error correction (FEC) coding / decoding of the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 handles the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-order phase shift keying (M-PSK), M-order quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be separated into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially pre-coded to generate multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine the coding and modulation schemes, as well as for spatial processing. Channel estimates may be derived from reference signals and / or channel state feedback sent by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318Tx. Each transmitter 318Tx may modulate a radio frequency (RF) carrier for transmission using a corresponding spatial stream.

[0060] At the UE 350, each receiver 354Rx receives a signal through its corresponding antenna 352. Each receiver 354Rx recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial stream destined for the UE 350. If multiple spatial streams are destined for the UE 350, they can be combined into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier and the reference signal are recovered and demodulated by determining the most likely signal constellation point sent by the base station 310. These soft decisions can be based on channel estimates calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by base station 310. The data and control signals are then provided to controller / processor 359, which implements layer 3 and layer 2 functionality.

[0061] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer readable medium. In the UL, the controller / processor 359 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets. The controller / processor 359 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0062] Similar to the functionality described in conjunction with DL transmissions performed by the base station 310, the controller / processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0063] Channel estimates derived by the channel estimator 358 based on a reference signal or feedback sent by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354Tx. Each transmitter 354Tx may modulate an RF carrier with a corresponding spatial stream for transmission.

[0064] UL transmissions are processed at the base station 310 in a manner similar to that described in conjunction with the receiver functionality at the UE 350. Each receiver 318Rx receives a signal through its respective antenna 320. Each receiver 318Rx recovers information modulated onto an RF carrier and provides the information to the RX processor 370.

[0065] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, control signal processing to recover IP packets. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0066] At least one of the TX processor 368, the RX processor 356, and the controller / processor 359 may be configured to combine Figure 1 The MT-SDT component 198 is used to perform various aspects.

[0067] At least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to combine Figure 1 The MT-SDT generation component 199 is used to perform various aspects.

[0068] When the UE is in the RRC idle state or the RRC inactive state, in order to send data, the UE may perform a complete RRC connection establishment procedure. The RRC connection establishment procedure for an idle user UE may include a random access (RA) procedure. The RA procedure may be used to initiate data transmission, but may have a large overhead cost compared to the size of the data to be sent. Similarly, the RA procedure may increase the latency of communication between the UE and the network. As an example, the RA procedure may include a message sequence including Msg1 (physical random access channel PRACH preamble), Msg2 (random access request (RAR)), Msg3 (RRC connection request, RRC connection reconstruction request, RRC connection recovery request, etc., depending on the reason for the RA procedure), Msg4 (early contention resolution, RRC connection setup, etc.), and Msg5 that can be used for UL data (unless SR / BSR is required before the actual payload is sent). This involves five or more messages for UL data before the actual payload is sent. This is a large overhead for applications that send uplink data that fits one transport block size (TBS).

[0069] After completing the RA procedure, UL transmission may be performed.This approach may include performing multiple message exchanges before the actual payload transmission of data occurs, even for very small and / or infrequent payloads.

[0070] When the amount of data to be sent is small (e.g., below a size threshold) (sending may be referred to as small data sending (SDT)), the access network may allow the UE to send uplink small data while remaining in an RRC inactive state, and the UE does not need to move to an RRC connected state to send uplink data. As an example, a random access-based SDT (i.e., RA-SDT) may enable the UE to send UL data through a 2-step or 4-step RACH procedure while the UE remains in an RRC inactive state. As another example, a configuration-grant-based SDT (i.e., CG-SDT) may include a network-configured PUSCH resource (e.g., a semi-static resource for uplink transmission) (e.g., reusing configuration grant type 1), and the UE may use previously configured resources to send small data when small data arrives for transmission without transitioning to an RRC connected state. Additionally, after the initial SDT, the UE may continue subsequent transmission / reception of small data in UL and DL without transitioning to an RRC connected state, and the state transition decision may be controlled by a network entity. Non-Access Stratum (NAS) message delivery within SDT may be enabled by configuring SRB1 and SRB2 for SDT in the RRC inactive state (NAS messages are transmitted via SRB2).

[0071] Aspects of the present disclosure provide a paging-triggered SDT to a UE while the UE remains in an RRC inactive state. For example, data transmission in the UL may transmit data (e.g., payload) in Msg1 or Msg3, rather than scheduling the first data transmission in Msg5 or thereafter as in conventional techniques. By providing data transmission for a UE in an RRC idle or RRC inactive state, power consumption, latency, and system overhead may be reduced.

[0072] The present disclosure presents enhancements to various aspects of MT-SDT, including but not limited to: MT-SDT indication by paging, MT-SDT indication by UE, RAN determination process as to whether to page UE for MT-SDT, MT-SDT with dual connectivity, MT-SDT indication in retrieval UE context request, and combination of MT-SDT and mobile originated small data transmission (MO-SDT). The enhancements apply to MT-SDT to support RA-SDT and CG-SDT as UL responses, and / or support MT-SDT procedures for initial DL data reception and subsequent UL / DL data transmission in RRC inactive state.

[0073] Figure 4 4 is a call flow diagram 400 illustrating a MT-SDT indication procedure by paging according to various aspects of the present disclosure. UE 402 may be in an RRC idle or RRC inactive state, such as shown at 409. Figure 4As shown, in one configuration, the CU-CP 406 may include an MT-SDT flag (e.g., an indication of MT-SDT) in an F1 application protocol (F1AP) message 414 between the CU-CP 406 and the DU 404 as an indication that the paging message for the UE is for MT-SDT. The DU 404 may include the MT-SDT flag in a Uu paging message 416 between the DU 404 and the UE 402. The network may include an access and mobility management function (AMF) 408. In one configuration, if a UE in RRC idle or RRC inactive mode is being paged by the network for MT-SDT (e.g., the network has data to send to the UE in MT-SDT), the AMF 408 may include an MT-SDT marker in an NG Application Protocol (NGAP) message 410 between the AMF 408 and the CU-CP 406, and the NGAP message may inform the CU-CP 406 that the paging of the UE in RRC idle or RRC inactive state is for MT-SDT. At 412, the CU-CP 406 may determine that the UE 402 is paged for MT-SDT. In response to the Uu paging message 416, the UE may respond by sending an RRC resume request message 418 indicating that the UE is ready to receive MT-SDT.

[0074] Figure 5 5 is a call flow diagram 500 illustrating MT-SDT indication by a UE according to various aspects of the present disclosure. UE 502 may be in an RRC idle or RRC inactive state, for example, as shown at 509. In some aspects, the indication from UE 502 may be in response to a combination of Figure 4 The Uu paging message 416 described above is transmitted and has been addressed as Figure 4 Such aspects in the present invention are marked with the same reference numerals. Figure 5As shown, various aspects may be used for the UE to indicate that it is ready to receive MT-SDT. In one configuration, the MT-SDT indication may be provided by the UE 502 via an RRC recovery request 518. The RRC recovery request 518 sent by the UE 502 may indicate that the RRC recovery request will receive MT-SDT from the network. In some aspects, the UE 502 may include in the RRC recovery request an MT-SDT flag (e.g., an indication) indicating that the recovery request is for MT-SDT or may indicate a recovery cause dedicated to MT-SDT. The recovery cause may indicate that the purpose of the RRC recovery request 518 is for MT-SDT reception. In some aspects, the UE may include MT-SDT assistance information in the RRC recovery request 518. In some aspects, instead of including a flag, cause, or other indication indicating that the request is for MT-SDT in the RRC recovery request 518, when the request is for an SDT that is ongoing due to MT-data, the UE 502 may use a specific different logical channel ID (LCID) to send the RRC recovery request. In such an example, the LCID for the RRC recovery request may indicate that the purpose of the request is for MT-SDT. In some aspects, the UE 502 may include an MT-SDT flag in an uplink medium access control-control element (MAC-CE) 520 that the UE 502 sends to the network in response to the paging message 416. The UE 502 may send an RRC recovery request 518 or a UL MAC-CE 520 to the CU-CP 506. Then, at 522, the network may respond by sending an MT-SDT to the UE 502 while the UE remains in an RRC inactive state and does not recover the RRC connection with the UE.

[0075] Figure 6 6 is a call flow diagram 600 illustrating a RAN determination process for paging a UE for MT-SDT according to various aspects of the present disclosure. The UE 602 may be in an RRC idle or RRC inactive state, for example, as shown at 609. Figure 6As shown, during the RAN determination process, the user plane function (UPF) 610 may transmit a DL data amount 614 to the CU-UP 606, which indicates the amount of data to be transmitted to the UE. The DL data amount 614 may be in bits (e.g., indicating the number of bits of data to be sent by the network to the UE) and may be transmitted to the CU-UP 606 via the N3 interface. When the DL data amount 614 is received from the UPF 610, at 616, the CU-CP 606 may notify the CU-CP 608 of the DL data amount. In some aspects, the CU-UP 606 may provide information about the amount of data to be provided to the UE in an E1 Application Protocol (E1AP) message (e.g., DL Data Notification) or a new E1AP message. The CU-CP 608 may then determine whether to page the UE for MD-SDT or for non-MD-SDT data transmission. For example, the determination may correspond to Figure 4 412 in. The Cu-CP 608 may make a determination based on a comparison of the amount of data to be sent to the UE and the MT-SDT threshold. In some aspects, the AMF 612 may indicate the MT-SDT threshold to the NG-RAN via an NG Application Protocol (NGAP) message 618 (e.g., an initial UE context setup request) or a new NGAP message. The MT-SDT threshold may be in bits (e.g., indicating a threshold number of bits that may be transmitted to the UE in the MT-SDT) and may help the CU-CP 608 determine whether to page the UE 602 for MT-SDT. For example, the CU-CP 608 may check at 620 whether the amount of DL data is less than the MT-SDT threshold for a Quality of Service (QoS) flow or bearer configured for MT-SDT. If the amount of data is less than the MT-SDT, the CU-CP may page 622 the UE 602 for MT-SDT, for example in conjunction with Figure 4 and / or Figure 5As described. If the amount of data is greater than the MT-SDT threshold, at 622, the CU-CP 608 may transmit a paging for non-SDT data transmission to the UE 602. The DU 604 may send a corresponding paging 624 (e.g., whether for MT-SDT according to the determination at 620), and the UE 602 may respond by sending an RRC recovery request 626 for MT-SDT or for non-SDT transmission based on the paging 624. The network may then send the data 628 to the UE 602. If the CU-CP 608 determines at 620 to send the data 628 in the MT-SDT, the UE 602 may receive the data while remaining in the RRC inactive state. The DL data amount and the MT-SDT threshold may be provided at different granularities, for example, at a protocol data unit (PDU) session, a QoS flow, or a data radio bearer (DRB). For example, the AMF 612 may provide one or more MT-SDT thresholds to the CU-CP 608, and each threshold may be for one or more specific PDU sessions, one or more QoS flows, or one or more DRBs.

[0076] Fig. 7A and Figure 7B 1 is a call flow diagram illustrating MT-SDT with dual connectivity according to various aspects of the present disclosure. In dual connectivity, a UE (e.g., such as a UE in conjunction with Figures 4 to 6 A UE described in any one of the foregoing may have a first connection with a first network node (e.g., a first base station) and a second connection with a second network node (e.g., a second base station). In some aspects, the two network nodes may be used for different radio access technologies, such as LTE and NR. One network node may be a master node, which may be referred to as a master control node in some aspects. The other node may be a secondary node. For the master node and the secondary node, the UE may be in an RRC idle or RRC inactive state. In some aspects, the secondary node may have data to be transmitted to the UE. Fig. 7A and Figure 7B An example aspect of determining at a primary node or a secondary node whether to transmit data to a UE as MT-SDT is illustrated. Fig. 7AAs shown, the network node may be a master node 702 for dual connectivity with a UE, and the master node 702 may determine whether to page the UE for MT-SDT. In some aspects, the master node 702 may receive an activity notification for the UE from a secondary node 704. The activity notification may indicate the amount of DL data that the secondary node has for sending to the UE on one or more secondary node terminated bearers. The secondary node 704 may indicate the amount of DL data to the master node 702 in an existing Xn message (e.g., an activity notification) or a new Xn message. In some aspects, for a master cell group (MCG) bearer terminated by a secondary node, the secondary node may only forward DL data, and the master node may decide whether to page the UE for MT-SDT based on the DL data.

[0077] like Figure 7B As shown, in another example, the network node may be a secondary node 704 for dual connectivity with the UE, and the secondary node 704 may determine whether to page the UE for MT-SDT, for example, rather than providing information to the primary node to enable the primary node to make a determination, such as Fig. 7A In this example, the master node 702 may indicate the MT-SDT threshold to the secondary node. In some aspects, the master node 702 may indicate the addition / modification of one or more MT-SDT thresholds, and the secondary node 704 may decide whether the amount of data to be sent to the UE is less than the threshold. For example, if the amount of data is less than or equal to the size threshold of the MT-SDT, the secondary node 704 may notify the master node 702 to perform MT-SDT. If the amount of data is greater than the threshold, the secondary node 704 may instruct the master node to page the UE without indicating MT-SDT. As shown in conjunction with Figure 6 As described, the MT-SDT threshold may be applicable to one or more QoS flows, one or more DRBs, one or more PDU sessions, etc. The primary node 702 may inform the secondary node 704 about the QoS flows or bearers to which the MT-SDT threshold applies.

[0078] Figure 8 8 is a call flow diagram 800 illustrating various aspects in which an MT-SDT indication may be provided in a UE context retrieval request in accordance with various aspects of the present disclosure. Figure 8 As shown, the network may include an anchor node 806 (e.g., an anchor base station) and a serving node 804 (e.g., a serving base station). At 810, the UE 802 may be in an RRC idle or RRC inactive state. At 812, the UPF 808 may indicate to the anchor node 806 that there is downlink data for the UE 802. The anchor node 806 may transmit a paging message 814 to the serving node 804. The paging message 814 may include an MT-SDT indication, or a recovery ID indicating that the data will be transmitted to the UE as an MT-SDT. At 816, the serving node 804 may page the UE 802 for the MT-SDT.

[0079] like Figure 8 As shown, UPF 808, anchor node 806, and serving node 804 may first send information related to MT-SDT, such as DL data and one or more indications for MT-SDT, to UE 802. UE 802 may transmit an RRC recovery request to serving node 804. The details of these procedures are similar to Figure 6 For example, paging 816 may include, for example, combining Figure 4 or Figure 5 Any of the aspects described herein. As illustrated at 816, the paging 816 may include a recovery ID or an indication to the UE that the paging is for MT-SDT. The UE 802 may respond by transmitting a random access Msg 1 818, and the serving node 804 may respond with a Msg 2 response 820. The UE 802 may send a Msg 3 with an RRC recovery request to receive the MT-SDT. The recovery request may indicate that the request is for MT-SDT, for example, as combined with Figure 5 As described.

[0080] When receiving the RRC recovery request from the UE 802, the service node 804 may include the MT-SDT flag and the MT-SDT assistance information (if any) in a retrieve UE context request message 824 to the anchor node 806. When receiving the message from the service node 804, the anchor node 806 may identify that this is MT-SDT based on the MT-SDT flag and the MT-SDT assistance information, and may transmit the DL data to the service node 804 in a retrieve UE context response message 826. Alternatively, the anchor node 806 may transmit the DL data to the service node 804 in a later step.

[0081] like Figure 8804. As further illustrated in FIG. 81 , the service node 804 may send Msg 4 816 to the UE 802. At 828, a path switching procedure may be performed to switch the path to the service node 804. Then, at 830, the UPF 808 may provide data for the MT-SDT to the service node 804. Then, the service node 804 may send DL data 832 to the UE 802 in the MT-SDT. In some aspects, the UE may continue to send UL data 834 (e.g., provided to the UPF at 836) after receiving the DL data 832 as the MO-SDT. In some aspects, the UE 802 may receive additional DL data 842 from the UPF as the MT-SDT (at 840) via the service node 804. As illustrated at 844, the service node 804 may transmit an RRC release to the UE. As shown at 846, the UE 802 may remain in an inactive state during the entire MT-SDT and / or MO-SDT transmission.

[0082] In some aspects, the UE may indicate that the UE has MO-SDT for transmission to the network by using specific RACH resources for SDT. For example, rather than sending tag specific information to the network in an RRC resume request for MO-SDT, the UE may send an RRC resume request using RACH resources dedicated to SDT. The resources on which the network receives the request indicate to the network that the request is for MO-SDT rather than resuming an RRC connection. Figure 8 As described, in some aspects, the criteria for both MT-SDT and MO-SDT may be met (e.g., both DL data and UL are less than or equal to a size threshold), and the efficiency of the UE indicating MO-SDT in the same RRC recovery request indicating that the UE is ready to receive MT-SDT may be improved.

[0083] In some aspects, the UE may include a flag for MT-SDT and for MO-SDT (e.g., the flag may include an indication of MT-SDT and a separate indication for MO-SDT, or the flag may include a single indication indicating both MT-SDT and MO-SDT in the RRC recovery request 822). In some aspects, the indication may include a recovery cause specific to MO-SDT and MT-SDT. In some aspects, the indication or the recovery cause may indicate that the ongoing SDT is due to both mobile originated data (e.g., MO-SDT) and mobile terminated data (e.g., MT-SDT).

[0084] When the MT-SDT+MO-SDT flag / indication is received in the RRC recovery request, the serving node may include this flag in the UE context retrieval request message 824 so that the anchor node knows that this is MT-SDT and MO-SDT and may plan subsequent data transmissions accordingly.

[0085] Alternatively, the UE may provide an MT-SDT indication / recovery cause in the RRC recovery request 822 and may send the RRC recovery request 822 using dedicated RACH resources for MO-SDT to indicate to the network that the request is for both MO-SDT and MT-SDT.

[0086] Fig. 9 900 is a flowchart illustrating a method of wireless communication according to various aspects of the present disclosure. The method may be performed by a network node for MT-SDT. The network node may be Figure 1 A base station or a component of a base station in an access network, or a core network component (e.g., base station 102, 310; CU 110; DU 130, 404, 504, 604; RU 140; CU-CP 406, 506, 608; CU-UP 606; AMF 408 612; UPF 610; master node 702; secondary node 704; anchor node 806; serving node 804; or Fig.13 The method provides signaling that helps enable MT-SDT, which can improve the efficiency of transmitting data from the network to the UE in the RRC idle or RRC inactive state.

[0087] like Fig. 9 As shown, at 902, the network node may transmit a paging message including a first indication of MT-SDT for a UE in an RRC idle or RRC inactive state. The UE may be Fig.13 902 may be performed by the MT-SDT generation component 199, for example. Figures 4 to 8 Various aspects of a network node providing a paging message including an indication of an MT-SDT are illustrated. Figure 4As shown, in one configuration, the network node may include a centralized unit control plane (CU-CP) 406, and the paging message including the first indication of the MT-SDT may be included in an F1 application protocol (F1AP) message between the CU-CP 406 and the distributed unit (DU) 404. In one configuration, the network node may include the DU 404, and the paging message including the first indication of the MT-SDT may be included in a Uu paging message between the DU 404 and the UE 402. In one configuration, the network node may include an access and mobility management function (AMF) 408, and the paging message including the first indication of the MT-SDT may be included in an NG application protocol (NGAP) message between the AMF 408 and the CU-CP 406.

[0088] At 904, the network node can transmit data to the UE for transmission while the UE remains in the RRC idle or RRC inactive state. 904 can be performed by the MT-SDT generation component 199, for example.

[0089] Fig.10 1000 is a flow chart of a method of wireless communication according to various aspects of the present disclosure. The method may be performed by a network node for MT-SDT. The network node may be Figure 1 A base station or a component of a base station in an access network, or a core network component (e.g., base station 102, 310; CU 110; DU 130, 404, 504, 604; RU 140; CU-CP 406, 506, 608; CU-UP 606; AMF 408 612; UPF 610; master node 702; secondary node 704; anchor node 806; serving node 804; or Fig.13 The method provides signaling that helps enable MT-SDT, which can improve the efficiency of transmitting data from the network to the UE in the RRC idle or RRC inactive state.

[0090] like Fig.10 As shown, at 1008, the network node may transmit a paging message including a first indication of a mobile terminated small data transfer (MT-SDT) for a user equipment (UE) in a radio resource control (RRC) inactive state. At 1010, the network node may receive a message including a second indication for MT-SDT from the UE. At 1012, when the UE remains in an RRC idle or RRC inactive state, the network node may transmit data to the UE for transmission, and may send data to the UE in response to the message including the second indication. The paging message may be transmitted, for example, by the MT-SDT generation component 199.

[0091] like Figure 5As shown, in one configuration, the second indication may include one or more of the following: an MT-SDT flag, an indication of a recovery reason for MT-SDT, MT-SDT assistance information, or a logical channel ID associated with MT-SDT. In one configuration, the message from the UE may include an RRC recovery request message. Alternatively, in another configuration, the message from the UE includes an uplink MAC-CE.

[0092] like Fig.10 As shown, in some aspects, the method of MT-SDT may also include step 1014. At 1014, when the UE remains in the RRC idle or RRC inactive state, the network node may receive uplink data from the UE. The receiving may be performed, for example, by the MT-SDT generation component 199. The uplink data from the UE may be sent as a MO-SDT, for example, as combined with Figure 8 In one configuration, the message from the UE may include a third indication for the MO-SDT. In another configuration, the message from the UE may be received in a random access resource associated with the MO-SDT, for example, as described in conjunction with Figure 8 As described.

[0093] In some aspects, a network node may include a CU-CP, and as Fig.10 As shown, the MT-SDT method may also include step 1002. At 1002, the CU-CP may receive a downlink data notification from a centralized unit user plane (CU-UP), the downlink data notification indicating an amount of downlink data for the UE. The reception may be performed, for example, by the MT-SDT generation component 199. The CU-CP may transmit a paging message including a first indication of MT-SDT based on the amount of downlink data for the UE indicated by the CU-UP being less than an MT-SDT threshold. In one configuration, the MT-SDT method may also include step 1004. At 1004, the CU-CP may receive an MT-SDT threshold from the AMF. For example, as Figure 6 As shown, the MT-SDT threshold may be sent via an NGAP message from the AMF 612 to the CU-CP 608. The MT-SDT threshold may be for a PDU session, a QoS flow, or a data radio bearer.

[0094] In some aspects, a network node may include a CU-UP, and as Fig.10 As shown, the MT-SDT method may also include step 1006. At 1006, the CU-UP may transmit a downlink data notification to the CU-CP, the downlink data notification indicating the amount of downlink data for the UE. The notification may be transmitted, for example, by the MT-SDT generation component 199. For example, Figure 6As shown, CU-UP 606 may transmit DL data notification to CU-CP 608 .

[0095] In some aspects, the network node may be a primary node for dual connectivity with the UE, and the method of MT-SDT may further include receiving an activity notification for the UE from the secondary node, and the primary node may transmit a paging message for the UE in response to the activity notification. In one configuration, the network node may be a secondary node for dual connectivity with the UE, and the method of MT-SDT may further include transmitting an activity notification for the UE to the primary node, and the primary node may transmit a paging message for the UE in response to the activity notification. Fig. 7A As shown, the activity notification received by the primary node 702 from the secondary node 704 may indicate an amount of downlink data for the UE on one or more secondary node terminated bearers.

[0096] In a scenario where the network node is a primary node for dual connectivity with the UE, the MT-SDT method may further include: transmitting an MT-SDT threshold for the UE to the secondary node; and receiving an MT-SDT indication from the secondary node. The primary node may send a paging message for the UE in response to the MT-SDT indication. In a scenario where the network node is a secondary node for dual connectivity with the UE, the MT-SDT method may further include: receiving an MT-SDT threshold for the UE from the primary node; and transmitting an MT-SDT indication to the primary node in response to downlink data for the UE having less than the MT-SDT threshold. For example, Figure 7B As shown, the master node 702 may transmit the MT-SDT threshold to the secondary node 704 during secondary node addition / modification, and the secondary node 704 may transmit the MT-SDT indication (indicating whether to perform MT-SDT) to the master node 702 based on the MT-SDT threshold.

[0097] In some aspects, the network node may include an anchor node. The anchor node may transmit a paging message for the UE to the serving node. In this scenario, the method of MT-SDT may also include receiving a request to retrieve a context for the UE from the serving node, the request including at least one of a second indication for MT-SDT or MT-SDT assistance information. The anchor node may forward data for the UE to the serving node in a UE context response in response to receiving the request.

[0098] Fig.11 1 is a flow chart 1100 illustrating a method of wireless communication according to various aspects of the present disclosure. The method may be performed by a user equipment (UE). The UE may be Fig.13The method provides signaling that helps enable MT-SDT for the UE, which can improve the efficiency of transmitting data from the network to the UE in the RRC idle or RRC inactive state.

[0099] like Fig.11 As shown, at 1102, the UE may receive a paging message from a network node. The network node may be Figure 1 A base station 102 or a component of a base station in an access network of Fig.13 The paging message may include a first indication of MT-SDT for the UE when the UE is in RRC idle or RRC inactive state. The reception may be performed, for example, by the MT-SDT component 198.

[0100] At 1104, the UE may send a message including a second indication for MT-SDT to the network node. At 1106, while the UE remains in the RRC idle or RRC inactive state, the UE may receive downlink data from the network node. The sending may be performed, for example, by the MT-SDT component 198.

[0101] In one configuration, the second indication may include one or more of the following: an MT-SDT flag, an indication of a recovery reason for the MT-SDT, MT-SDT assistance information, or a logical channel identifier (ID) associated with the MT-SDT. In one configuration, the message from the UE includes an RRC recovery request message. In one configuration, the message from the UE includes an uplink medium access control-control element (MAC-CE). For example, Figure 5 As shown, the message from UE 502 may include an RRC recovery request message or a ULMAC CE message.

[0102] Fig.12 1200 is a flowchart illustrating a method of wireless communication according to various aspects of the present disclosure. The method may be performed by a user equipment (UE). The UE may be Fig.13 The method provides signaling that helps enable MT-SDT for the UE, which can improve the efficiency of transmitting data from the network to the UE in the RRC idle or RRC inactive state.

[0103] like Fig.12 As shown, at 1202, the UE may receive a paging message from a network node, the paging message including a first indication of MT-SDT for the UE when the UE is in an RRC idle or RRC inactive state. The receiving may be performed, for example, by the MT-SDT component 198. Figure 4 , Figure 5 , Figure 6 and Figure 8 Various examples in which the UE receives a paging message indicating MT-SDT are illustrated.

[0104] At 1204, the UE may send a message including a second indication for MT-SDT to the network node. The sending may be performed, for example, by the MT-SDT component 198. Figure 5 , Figure 6 and Figure 8 Various examples of the UE sending a message for MT-SDT to the network are illustrated.

[0105] At 1206, while the UE remains in the RRC idle or RRC inactive state, the UE may receive downlink data from the network node. Figure 5 , Figure 6 and Figure 8 Various examples of UE receiving MT-SDT are illustrated.

[0106] At 1208, the UE may send uplink data to the network node while the UE remains in the RRC idle or RRC inactive state. In one configuration, the message from the UE may also include a third indication for the MO-SDT. In another configuration, the message may be received in a random access resource associated with the MO-SDT. Figure 8 An example in which the UE sends MO-SDT in conjunction with MT-SDT is illustrated.

[0107] Fig.131300 is a diagram illustrating an example of a hardware implementation for an apparatus 1304. The apparatus 1304 may be a UE, a component of a UE, or may implement UE functionality. In some aspects, the apparatus 1304 may include a cellular baseband processor 1324 (also referred to as a modem) coupled to one or more transceivers 1322 (e.g., a cellular RF transceiver). The cellular baseband processor 1324 may include on-chip memory 1324'. In some aspects, the apparatus 1304 may also include one or more subscriber identity module (SIM) cards 1320 and an application processor 1306 coupled to a secure digital (SD) card 1308 and a screen 1310. The application processor 1306 may include on-chip memory 1306'. In some aspects, the device 1304 may also include a Bluetooth module 1312, a WLAN module 1314, an SPS module 1316 (e.g., a GNSS module), one or more sensor modules 1318 (e.g., an atmospheric pressure sensor / altimeter; a motion sensor such as an inertial measurement unit (IMU), a gyroscope, and / or an accelerometer; light detection and ranging (LIDAR), radio-aided detection and ranging (RADAR), sound navigation and ranging (SONAR), a magnetometer, audio, and / or other technologies for positioning), an additional memory module 1326, a power source 1330, and / or a camera 1332. The Bluetooth module 1312, the WLAN module 1314, and the SPS module 1316 may include an on-chip transceiver (TRX) (or in some cases, only a receiver (RX)). The Bluetooth module 1312, the WLAN module 1314, and the SPS module 1316 may include their own dedicated antennas and / or communicate using antennas 1380. The cellular baseband processor 1324 communicates with the UE 104 and / or with the RU associated with the network entity 1302 through the transceiver 1322 via one or more antennas 1380. The cellular baseband processor 1324 and the application processor 1306 may each include a computer-readable medium / memory 1324', 1306', respectively. The additional memory module 1326 may also be considered as a computer-readable medium / memory. Each computer-readable medium / memory 1324', 1306', 1326 may be non-transitory. The cellular baseband processor 1324 and the application processor 1306 are each responsible for general processing, including executing software stored on a computer-readable medium / memory. The software enables the cellular baseband processor 1324 / application processor 1306 to perform the various functions described above when executed by the cellular baseband processor 1324 / application processor 1306. The computer-readable medium / memory can also be used to store data manipulated by the cellular baseband processor 1324 / application processor 1306 when executing the software.The cellular baseband processor 1324 / application processor 1306 may be a component of the UE 350 and may include the memory 360 and / or at least one of the TX processor 368, the RX processor 356, and the controller / processor 359. In one configuration, the device 1304 may be a processor chip (modem and / or application) and include only the cellular baseband processor 1324 and / or the application processor 1306, and in another configuration, the device 1304 may be the entire UE (e.g., see. Figure 3 350) and includes additional modules of device 1304.

[0108] As discussed above, the MT-SDT component 198 is configured to: send a message including a second indication for MT-SDT to the network node; and receive downlink data from the network node when the UE remains in the RRC idle or RRC inactive state. The MT-SDT component 198 may also be configured to perform a combined Fig.11 or Fig.12 Described by the flowchart in or by Figure 4 , Figure 5 , Figure 6 or Figure 8 Any of the aspects performed by the UE in any of the . The MT-SDT receiving component 198 may be within the cellular baseband processor 1324, the application processor 1306, or both the cellular baseband processor 1324 and the application processor 1306. The MT-SDT component 198 may be one or more hardware components that are specifically configured to perform the process / algorithm, implemented by one or more processors configured to perform the process / algorithm, stored in a computer-readable medium for implementation by one or more processors, or some combination of the foregoing. As shown, the device 1304 may include multiple components configured for various functions. In one configuration, the device 1304 (and specifically the cellular baseband processor 1324 and / or the application processor 1306) includes: a component for receiving a paging message from a network node; a component for sending a message including a second indication for MT-SDT to the network node; and a component for receiving downlink data from the network node when the UE remains in an RRC idle or RRC inactive state. The device may also include a component for performing a combined Fig.11 or Fig.12 Described by the flowchart in or by Figure 4 , Figure 5 , Figure 6 or Figure 81304. The components may be performed by the MT-SDT component 198 of the apparatus 1304 configured to perform the functions recited by the components. As described above, the apparatus 1304 may include a TX processor 368, an RX processor 356, and a controller / processor 359. Thus, in one configuration, the components may be the TX processor 368, the RX processor 356, and / or the controller / processor 359 configured to perform the functions recited by the components.

[0109] Fig.14 1400 is a diagram illustrating an example of a hardware implementation for a network entity 1402. The network entity 1402 may be a BS, a component of a BS, or may implement BS functionality. The network entity 1402 may include at least one of a CU 1410, a DU 1430, or a RU 1440. For example, depending on the layer functionality handled by the component 199, the network entity 1402 may include a CU 1410; both a CU 1410 and a DU 1430; each of the CU 1410, the DU 1430, and the RU 1440; the DU 1430; both the DU 1430 and the RU 1440; or the RU 1440. The CU 1410 may include a CU processor 1412. The CU processor 1412 may include an on-chip memory 1412'. In some aspects, the CU 1410 may also include an additional memory module 1414 and a communication interface 1418. CU 1410 communicates with DU 1430 via a midhaul link, such as an F1 interface. DU 1430 may include a DU processor 1432. DU processor 1432 may include on-chip memory 1432'. In some aspects, DU 1430 may also include additional memory modules 1434 and a communication interface 1438. DU 1430 communicates with RU 1440 via a fronthaul link. RU 1440 may include a RU processor 1442. RU processor 1442 may include on-chip memory 1442'. In some aspects, RU 1440 may also include additional memory modules 1444, one or more transceivers 1446, antenna 1480, and communication interface 1448. RU 1440 communicates with UE 104. On-chip memory 1412', 1432', 1442' and additional memory modules 1414, 1434, 1444 may each be considered a computer-readable medium / memory. Each computer readable medium / memory may be non-transitory. Each of processors 1412, 1432, 1442 is responsible for general processing, including executing software stored on the computer readable medium / memory. The software, when executed by the corresponding processor, causes the processor to perform the various functions described above. The computer readable medium / memory may also be used to store data manipulated by the processor when executing the software.

[0110] As discussed above, the MT-SDT generation component 199 may be configured to: transmit a paging message including a first indication of an MT-SDT for a UE in an RRC idle or RRC inactive state; and transmit data to the UE for transmission while the UE remains in the RRC idle or RRC inactive state. The MT-SDT generation component 199 may also be configured to perform a combined Fig. 9 or Fig.10 Described by the flowchart in or by Figures 4 to 8 Any of the aspects performed by a network node in any of the . MT-SDT generation component 199 may be within one or more processors of one or more of the CU 1410, the DU 1430, and the RU 1440. Component 199 may be one or more hardware components specifically configured to execute the process / algorithm, implemented by one or more processors configured to execute the process / algorithm, stored in a computer-readable medium for implementation by one or more processors, or some combination thereof. The network entity 1402 may include a variety of components configured for various functions. In one configuration, the network entity 1402 includes: a component for transmitting a paging message, the paging message including a first indication of a mobile terminated small data transmission (MT-SDT) for a user equipment (UE) that is in a radio resource control (RRC) inactive state; and a component for transmitting data to the UE for transmission when the UE remains in an RRC idle or RRC inactive state. The network entity may also include a component for performing a combined Fig. 9 or Fig.10 Described in the flowchart and / or by Figures 4 to 8 The components may be executed by the MT-SDT generation component 199 of the network entity 1402 configured to perform the functions recited by the components. As described above, the network entity 1402 may include the TX processor 316, the RX processor 370, and the controller / processor 375. Therefore, in one configuration, the components may be the TX processor 316, the RX processor 370, and / or the controller / processor 375 configured to perform the functions recited by the components.

[0111] Fig.151500 is an example of a hardware implementation for a network entity 1560. In one example, the network entity 1560 may be within the core network 120. The network entity 1560 may include a network processor 1512. The network processor 1512 may include an on-chip memory 1512'. In some aspects, the network entity 1560 may also include an additional memory module 1514. The network entity 1560 communicates with the CU 1502 directly (e.g., a backhaul link) or indirectly (e.g., through the RIC) via a network interface 1580. The on-chip memory 1512' and the additional memory module 1514 may each be considered as a computer-readable medium / memory. Each computer-readable medium / memory may be non-transitory. The processor 1512 is responsible for general processing, including executing software stored on a computer-readable medium / memory. The software, when executed by the corresponding processor, enables the processor to perform the various functions described above. The computer-readable medium / memory may also be used to store data manipulated by the processor when executing the software.

[0112] As discussed above, the MT-SDT generation component 199 can be configured to perform, for example, Figure 4 , Figure 6 or Figure 8 Any of the aspects described for the AMF or UPF in the . MT-SDT generation component 199 may be within the processor 1512. The MT-SDT generation component may be one or more hardware components that are specifically configured to perform the process / algorithm, implemented by one or more processors configured to perform the process / algorithm, stored in a computer-readable medium for implementation by one or more processors, or some combination of the above. The network entity 1560 may include a variety of components configured for various functions. In one configuration, the network entity 1560 includes: a component for sending a transmission paging message, the paging message including a first indication of a mobile terminated small data transmission (MT-SDT) for a user equipment (UE) in a radio resource control (RRC) inactive state; and a component for transmitting data to the UE for transmission when the UE remains in an RRC idle or RRC inactive state. The component may be executed by the MT-SDT generation component 199 of the network entity 1560 that is configured to perform the functions recorded by the component.

[0113] Various aspects of the present disclosure provide a paging-triggered SDT for a UE while the UE remains in an inactive state. The disclosed method presents enhancements to various aspects of MT-SDT, including but not limited to: MT-SDT indication by paging, MT-SDT indication by the UE, NG-RAN determination process as to whether to page the UE for MT-SDT, MT-SDT with dual connectivity, MT-SDT indication in a request to retrieve a UE context, and a combination of MT-SDT and mobile originated small data transmission (MO-SDT). The enhanced aspects of MT-SDT apply to RA-SDT and CG-SDT as UL responses, and support MT-SDT procedures for initial DL data reception and subsequent UL / DL data transmission in RRC idle or RRC inactive states. By providing data transmission for UEs in idle or inactive states, power consumption, latency, and system overhead can be beneficially reduced.

[0114] It should be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is merely an illustration of the exemplary method. It should be understood that the specific order or hierarchy of the blocks in the process / flowchart may be rearranged based on design preferences. Further, some blocks may be combined or omitted. The attached method claims provide the elements of the various blocks in a sample order, but are not limited to the specific order or hierarchy provided.

[0115] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Therefore, the claims are not limited to the various aspects described herein, but should be given the full scope consistent with the language claims. Unless otherwise specified, reference to an element in the singular form does not mean "one and only one", but "one or more". Terms such as "if", "when" and "while" do not mean a direct temporal relationship or reaction. That is, these phrases, such as "when ......", do not mean an immediate action in response to the occurrence of an action or during the occurrence of an action, but simply imply that if the conditions are met, the action will occur, but no specific or immediate time limit is required for the occurrence of the action. The word "exemplary" is used herein to mean "used as an example, instance, or illustration". Any aspect described as "exemplary" herein is not necessarily interpreted as being preferred or having advantages over other aspects. Unless otherwise specified, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C", "one or more of A, B, or C", "at least one of A, B and C", "one or more of A, B, and C", and "A, B, C, or any combination thereof" include any combination of A, B, and / or C, which may include multiple A, multiple B, or multiple C. Specifically, combinations such as "at least one of A, B, or C", "one or more of A, B, or C", "at least one of A, B, and C", "one or more of A, B, and C", and "A, B, C, or any combination thereof" may be only A, only B, only C, A and B, A and C, B and C, or A and B and C, where any such combination may contain one or more members of A, B, or C. A set should be interpreted as a set of elements, where the number of elements is one or more. Thus, for a set of X, X will include one or more elements. If the first device receives data from the second device or sends data to the second device, the data may be received / sent directly between the first device and the second device, or indirectly between the first device and the second device through a collection of devices. All structural and functional equivalents of the elements of the various aspects described throughout the present disclosure that are known or will later be known to a person of ordinary skill in the art are expressly incorporated herein by reference and are covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims. Words such as "module", "mechanism", "element", "device", etc. cannot replace the word "component". Therefore, no claim element will be understood as a component plus function unless the element is explicitly stated using the phrase "component for..."

[0116] As used herein, the phrase "based on" should not be interpreted as referring to a closed set of information, one or more conditions, one or more factors, etc. In other words, the phrase "based on A" (where "A" can be information, a condition, a factor, etc.) should be interpreted as "based at least on A" unless specifically stated differently.

[0117] The following aspects are merely illustrative and may be combined with other aspects or teachings described herein without limitation.

[0118] Aspect 1 is a method of wireless communication at a network node. The method includes: transmitting a paging message including a first indication of a mobile terminated small data transmission (MT-SDT) for a user equipment (UE) in a radio resource control (RRC) inactive state; and transmitting data to the UE for transmission while the UE remains in the RRC inactive state.

[0119] Aspect 2 is a method according to aspect 1, wherein the network node includes a centralized unit control plane (CU-CP), and the paging message including the first indication of the MT-SDT is included in an F1 application protocol (F1AP) message between the CU-CP and a distributed unit (DU).

[0120] Aspect 3 is a method according to aspect 1, wherein the network node includes a distributed unit (DU), and the paging message including the first indication of the MT-SDT is included in a Uu paging message between the DU and the UE.

[0121] Aspect 4 is a method according to Aspect 1, wherein the network node includes an access and mobility management function (AMF), and the paging message including the first indication of the MT-SDT is included in an NG Application Protocol (NGAP) message between the AMF and a centralized unit control plane (CU-CP).

[0122] Aspect 5 is a method according to aspect 1, wherein the method further comprises receiving a message including a second indication for the MT-SDT from the UE, wherein the data is sent to the UE in response to the message including the second indication.

[0123] Aspect 6 is a method according to any one of Aspect 5, wherein the second indication includes one or more of the following: an MT-SDT flag, an indication of a recovery reason for the MT-SDT, MT-SDT assistance information, or a logical channel identifier (ID) associated with the MT-SDT.

[0124] Aspect 7 is a method according to aspect 5, wherein the message from the UE includes an RRC recovery request message.

[0125] Aspect 8 is a method according to aspect 5, wherein the message from the UE includes an uplink medium access control-control element (MAC-CE).

[0126] Aspect 9 is a method according to Aspect 5, wherein the message from the UE also includes a third indication for mobile-initiated small data transmission (MO-SDT), and the method also includes: receiving uplink data from the UE when the UE remains in the RRC inactive state.

[0127] Aspect 10 is a method according to aspect 5, wherein the message is received in a random access resource associated with mobile-originated small data transmission (MO-SDT), and the method further includes: receiving uplink data from the UE when the UE remains in the RRC inactive state.

[0128] Aspect 11 is a method according to aspect 1, wherein the network node includes a centralized unit control plane (CU-CP), and the method further includes: receiving a downlink data notification from a centralized unit user plane (CU-UP), the downlink data notification indicating an amount of downlink data for the UE, wherein the CU-CP transmits the paging message including the first indication of the MT-SDT based on the amount of downlink data for the UE indicated by the CU-UP being less than an MT-SDT threshold.

[0129] Aspect 12 is a method according to aspect 11, wherein the method further comprises: receiving the MT-SDT threshold from an access and mobility management function (AMF).

[0130] Aspect 13 is a method according to any one of aspects 11 and 12, wherein the MT-SDT threshold is for a protocol data unit (PDU) session, a quality of service (QoS) flow, or a data radio bearer.

[0131] Aspect 14 is a method according to aspect 1, wherein the network node includes a centralized unit user plane (CU-UP), and the method further includes: transmitting a downlink data notification to a centralized unit control plane (CU-CP), the downlink data notification indicating an amount of downlink data for the UE.

[0132] Aspect 15 is a method according to aspect 1, wherein the network node includes an access and mobility management function (AMF), and the method further includes: transmitting the MT-SDT threshold to a centralized unit control plane (CU-CP).

[0133] Aspect 16 is a method according to aspect 1, wherein the network node is a primary node for dual connectivity with the UE, and the method further includes: receiving an activity notification for the UE from a secondary node, the activity notification indicating an amount of downlink data for the UE on one or more secondary node terminated bearers, wherein the primary node transmits the paging message for the UE in response to the activity notification.

[0134] Aspect 17 is a method according to Aspect 1, wherein the network node is a secondary node for dual connectivity with the UE, and the method further includes: transmitting an activity notification for the UE to a primary node, the activity notification indicating an amount of downlink data for the UE on bearers terminated by one or more secondary nodes, wherein the primary node transmits the paging message for the UE in response to the activity notification.

[0135] Aspect 18 is a method according to aspect 1, wherein the network node is a primary node for dual connectivity with the UE, and the method further includes: transmitting an MT-SDT threshold for the UE to a secondary node; and receiving an MT-SDT indication from the secondary node, wherein the primary node transmits the paging message for the UE in response to the MT-SDT indication.

[0136] Aspect 19 is a method according to aspect 1, wherein the network node is a secondary node for dual connectivity with the UE, and the method further includes: receiving an MT-SDT threshold for the UE from a primary node; and transmitting an MT-SDT indication to the primary node in response to downlink data for the UE having a value less than the MT-SDT threshold.

[0137] Aspect 20 is a method according to aspect 1, wherein the network node includes an anchor node, the anchor node transmits the paging message for the UE to a service node, and the method also includes: receiving a request to retrieve a context for the UE from the service node, the request including at least one of the second indication for the MT-SDT or MT-SDT assistance information, wherein the anchor node forwards the data for the UE to the service node in a UE context response in response to receiving the request.

[0138] Aspect 21 is a device comprising components for performing the method according to any one of aspects 1 to 20.

[0139] Aspect 22 is a device comprising: a memory; and at least one processor, the at least one processor being coupled to the memory and configured to execute a method according to any one of Aspects 1 to 20 based at least in part on information stored in the memory.

[0140] In aspect 23, the apparatus according to aspect 21 or 22 further comprises at least one transceiver.

[0141] Aspect 24 is a non-transitory computer readable medium storing computer executable code at a network node, which, when executed by a processor, causes the processor to perform the method according to any one of aspects 1 to 20.

[0142] Aspect 25 is a method for performing wireless communication at a UE, the method comprising: receiving a paging message from a network node, the paging message including a first indication of an MT-SDT for the UE when the UE is in an RRC inactive state; sending a message including a second indication for the MT-SDT to the network node; and receiving downlink data from the network node while the UE remains in the RRC inactive state.

[0143] In aspect 26, the method according to aspect 25 further includes: the second indication includes one or more of the following: an MT-SDT flag, an indication of a recovery reason of the MT-SDT, MT-SDT assistance information, or a logical channel ID associated with the MT-SDT.

[0144] In aspect 27, the method according to aspect 25 or 26 further comprises: the message from the UE comprises an RRC recovery request message or an uplink MAC-CE.

[0145] In aspect 28, the method according to any one of aspects 25 to 27 further includes: the message from the UE further includes a third indication for MO-SDT, and the method further includes: when the UE remains in the RRC inactive state, sending uplink data to the network node.

[0146] In aspect 29, the method according to any one of aspects 25 to 27 also includes: the message is received in a random access resource associated with MO-SDT, and the method also includes: when the UE remains in the RRC inactive state, sending uplink data to the network node.

[0147] Aspect 30 is an apparatus comprising means for performing the method according to any one of aspects 25 to 29.

[0148] Aspect 31 is a device comprising: a memory; and at least one processor, the at least one processor being coupled to the memory and being configured to execute a method according to any one of Aspects 25 to 29 based at least in part on information stored in the memory.

[0149] In aspect 32, the apparatus according to aspect 30 or 31 further comprises at least one transceiver.

[0150] Aspect 33 is a non-transitory computer readable medium storing computer executable code at a network node, which, when executed by a processor, causes the processor to perform a method according to any one of aspects 25 to 29.

Claims

1. An apparatus for wireless communication at a network node, the apparatus comprising: Memory; and at least one processor coupled to the memory and based at least in part on the information stored in the memory, the at least one processor configured to: transmitting a paging message including a first indication of a mobile terminated small data transmission (MT-SDT) for a user equipment (UE) in a radio resource control (RRC) inactive state; as well as While the UE remains in the RRC inactive state, data is transmitted to the UE for transmission.

2. The apparatus of claim 1 , wherein the network node comprises a centralized unit control plane (CU-CP), and the paging message comprising the first indication of the MT-SDT is included in an F1 Application Protocol (F1AP) message between the CU-CP and a distributed unit (DU).

3. The apparatus of claim 1, wherein the network node comprises a distributed unit (DU), and the paging message including the first indication of the MT-SDT is included in a Uu paging message between the DU and the UE.

4. The apparatus of claim 1 , wherein the network node comprises an access and mobility management function (AMF), and the paging message comprising the first indication of the MT-SDT is included in an NG Application Protocol (NGAP) message between the AMF and a centralized unit control plane (CU-CP).

5. The apparatus of claim 1 , wherein the at least one processor is further configured to: A message including a second indication for the MT-SDT is received from the UE, wherein the data is sent to the UE in response to the message including the second indication.

6. The apparatus of claim 5, wherein the second indication comprises one or more of: MT-SDT mark, Indicates the reason for the MT-SDT recovery, MT-SDT assistance information, or A logical channel identifier (ID) associated with the MT-SDT.

7. The apparatus of claim 5, wherein the message from the UE comprises an RRC recovery request message.

8. The apparatus of claim 5, wherein the message from the UE comprises an uplink Medium Access Control - Control Element (MAC-CE).

9. The apparatus of claim 5, wherein the message from the UE further comprises a third indication for mobile originated small data transmission (MO-SDT), the at least one processor being further configured to: While the UE remains in the RRC inactive state, uplink data is received from the UE.

10. The apparatus of claim 5, wherein the message is received in a random access resource associated with a mobile originated small data transmission (MO-SDT), the at least one processor being further configured to: While the UE remains in the RRC inactive state, uplink data is received from the UE.

11. The apparatus of claim 1 , wherein the network node comprises a centralized unit control plane (CU-CP), the at least one processor being further configured to: receiving a downlink data notification indicating an amount of downlink data for the UE from a centralized unit user plane (CU-UP), wherein the CU-CP transmits the paging message including the first indication of the MT-SDT based on the amount of downlink data for the UE indicated by the CU-UP being less than an MT-SDT threshold.

12. The apparatus of claim 11, wherein the at least one processor is further configured to: The MT-SDT threshold is received from an Access and Mobility Management Function (AMF).

13. The apparatus of claim 12, wherein the MT-SDT threshold is for a protocol data unit (PDU) session, a quality of service (QoS) flow, or a data radio bearer.

14. The apparatus of claim 1, wherein the network node comprises a centralized unit user plane (CU-UP), the at least one processor being further configured to: A downlink data notification is transmitted to a centralized unit control plane (CU-CP), the downlink data notification indicating an amount of downlink data for the UE.

15. The apparatus of claim 1, wherein the network node comprises an access and mobility management function (AMF), the at least one processor being further configured to: The MT-SDT threshold is communicated to the Centralized Unit Control Plane (CU-CP).

16. The apparatus of claim 1, wherein the network node is a master node for dual connectivity with the UE, the at least one processor being further configured to: An activity notification for the UE is received from a secondary node, the activity notification indicating an amount of downlink data for the UE on one or more secondary node terminated bearers, wherein the primary node transmits the paging message for the UE in response to the activity notification.

17. The apparatus of claim 1, wherein the network node is a secondary node for dual connectivity with the UE, the at least one processor being further configured to: An activity notification for the UE is transmitted to a primary node, the activity notification indicating an amount of downlink data for the UE on one or more secondary node terminated bearers, wherein the primary node transmits the paging message for the UE in response to the activity notification.

18. The apparatus of claim 1, wherein the network node is a master node for dual connectivity with the UE, the at least one processor being further configured to: transmitting, to a secondary node, an MT-SDT threshold for the UE; and An MT-SDT indication is received from the secondary node, wherein the primary node transmits the paging message for the UE in response to the MT-SDT indication.

19. The apparatus of claim 1, wherein the network node is a secondary node for dual connectivity with the UE, the at least one processor being further configured to: receiving, from a master node, an MT-SDT threshold for the UE; and In response to downlink data for the UE having a value less than the MT-SDT threshold, transmitting an MT-SDT indication to the master node.

20. The apparatus of claim 1, wherein the network node comprises an anchor node that transmits the paging message for the UE to a serving node, the at least one processor being further configured to: receiving, from the serving node, a request to retrieve a context for the UE, the request comprising at least one of a second indication for the MT-SDT or MT-SDT assistance information, wherein the anchor node forwards the data for the UE to the serving node in a UE context response in response to receiving the request.

21. The apparatus according to claim 1, further comprising: At least one transceiver is coupled to the at least one processor and configured to transmit the paging message.

22. An apparatus for wireless communication at a user equipment (UE), the apparatus comprising: Memory; and at least one processor coupled to the memory and based at least in part on the information stored in the memory, the at least one processor configured to: receiving a paging message from a network node, the paging message including a first indication of a mobile terminated small data transmission (MT-SDT) for the UE when the UE is in a radio resource control (RRC) inactive state; sending a message including a second indication for the MT-SDT to the network node; as well as While the UE remains in the RRC inactive state, downlink data is received from the network node.

23. The apparatus of claim 22, wherein the second indication comprises one or more of: MT-SDT mark, Indicates the reason for the restoration of the MT-SDT, MT-SDT auxiliary information, or A logical channel identifier (ID) associated with the MT-SDT.

24. The apparatus of claim 22, wherein the message from the UE comprises an RRC recovery request message.

25. The apparatus of claim 22, wherein the message from the UE comprises an uplink Medium Access Control - Control Element (MAC-CE).

26. The apparatus of claim 22, wherein the message from the UE further comprises a third indication for mobile originated small data transmission (MO-SDT), the at least one processor being further configured to: When the UE remains in the RRC inactive state, uplink data is sent to the network node.

27. The apparatus of claim 22, wherein the message is received in a random access resource associated with a mobile originated small data transmission (MO-SDT), the at least one processor being further configured to: When the UE remains in the RRC inactive state, uplink data is sent to the network node.

28. The apparatus according to claim 22, further comprising: At least one transceiver is coupled to the at least one processor and configured to receive the paging message.

29. A method for wireless communication at a network node, the method comprising: transmitting a paging message including a first indication of a mobile terminated small data transfer (MT-SDT) for a user equipment (UE) in a radio resource control (RRC) inactive state; as well as While the UE remains in the RRC inactive state, data is transmitted to the UE for transmission.

30. A method of wireless communication at a user equipment (UE), comprising: receiving a paging message from a network node, the paging message including a first indication of a mobile terminated small data transfer (MT-SDT) for the UE when the UE is in a radio resource control (RRC) inactive state; sending a message including a second indication for the MT-SDT to the network node; as well as While the UE remains in the RRC inactive state, downlink data is received from the network node.

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