Paging for Small Data Transmission (SDT) by Mobile Termination (MT)

Abstract

The present disclosure relates to a user equipment (UE), a network node, and a method for the UE and the network node. The UE includes a transceiver and a circuit. The circuit receives a paging message even in an inactive state. In response to the paging message, the circuit determines to remain in an inactive state for receiving small data. While remaining in the inactive state, the circuit transmits a response to the paging message to the network node at a transmission opportunity associated with a pre-configured resource.

Description

[Technical field]

[0001] 1.Technical Field FIELD OF THE DISCLOSURE The present disclosure relates to transmitting and receiving signals in a communication system. In particular, the present disclosure relates to methods and apparatus for such transmission and reception. [Background technology]

[0002] 2. Description of Related Technology The 3rd Generation Partnership Project (3GPP) is working on technical specifications for next-generation cellular technology, also known as 5th generation (5G), including New Radio (NR) access technology (RAT) operating in the frequency range up to 100 GHz. NR is the successor to technologies represented by Long Term Evolution (LTE) and LTE Advanced (LTE-A).

[0003] In systems such as LTE and NR, further improvements and options may facilitate efficient operation of the communication system and certain devices associated with the communication system. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TS 38.300 v15.6.0 [Non-Patent Document 2] 3GPP TS 38.211 [Non-Patent Document 3] ITU-R M.2083 [Non-Patent Document 4] 3GPP TR 38.913 [Non-Patent Document 5] 3GPP TS 23.501 [Non-Patent Document 6] 3GPP TS 38.212 [Non-Patent Document 7] 3GPP TS 38.321 [Non-Patent Document 8] 3GPP TS 38.331 [Non-Patent Document 9] 3GPP TR 25.705 v13.0.0 [Non-Patent Document 10] 3GPP TSG-RAN2 Meeting #117e R2-2204216 Summary of the Invention [Problem to be solved by the invention]

[0005] One of several non-limiting exemplary embodiments facilitates efficient handling of mobile-terminated small data transmissions during inactivity states.

[0006] In one embodiment, the technology disclosed herein features an apparatus (e.g., User Equipment (UE)) comprising a transceiver and circuitry. In operation, the circuitry receives a paging message while in an inactive state. In response to the paging message, the circuitry determines to remain in an inactive state to receive small data. While remaining in the inactive state, at a transmission opportunity associated with a pre-configured resource, the circuitry transmits a response to the paging message to a network node.

[0007] It should be noted that the general or specific embodiments may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any combination thereof. For example, the integrated circuit may control processing of a UE or a base station.

[0008] Further benefits and advantages of the disclosed embodiments and various implementations will become apparent from the specification and drawings, which may be obtained individually by the various embodiments and features of the specification and drawings, and it is not necessary for all of them to be present in order to obtain one or more of such benefits and / or advantages. [Brief description of the drawings]

[0009] Exemplary embodiments will now be described in more detail with reference to the accompanying drawings. [Figure 1] FIG. 1 illustrates an example architecture of a 3GPP NR system. [Diagram 2] Schematic diagram showing the division of functions between NG-RAN and 5GC [Diagram 3] Sequence diagram of RRC connection establishment / reconfiguration procedure [Figure 4] Schematic showing the usage scenarios for Enhanced Mobile Broadband (eMBB), Massive Machine Type Communications (mMTC), and Ultra-Reliable Low Latency Communications (URLLC) [Diagram 5] Block diagram illustrating an exemplary 5G system architecture for a non-roaming scenario [Figure 6] Diagram showing the contention-based RACH procedure [Figure 7] Diagram showing the contention-free RACH procedure [Figure 8] Diagram showing possible RRC state changes [Figure 9] Diagram showing message exchange for the RRC Resume procedure [Figure 10] Diagram showing message exchange for the RRC Release procedure [Figure 11] Diagram showing message exchange for the RRC Release procedure [Figure 12] FIG. 1 illustrates a prior art message exchange for uplink data transmission involving a UE state change from an Inactive state to a Connected state. [Figure 13] FIG. 1 illustrates an example 4-step RACH that an RRC_INACTIVE UE can use to transmit small data on the uplink. [Figure 14] FIG. 1 illustrates an example two-step RACH that an RRC_INACTIVE UE can use to transmit small data on the uplink. [Figure 15] FIG. 1 illustrates an example paging procedure for downlink small data transmission. [Figure 16] A block diagram illustrating an example functional configuration of a network node and a user equipment. [Figure 17] FIG. 17 is a block diagram illustrating an example functional configuration of a circuit for processing small data that may be included in the example user equipment of FIG. [Figure 18] FIG. 17 is a block diagram illustrating an example functional configuration of an SDT handling circuit that may be included in the example scheduling device of FIG. 16. [Figure 19] 1 is a flow chart illustrating exemplary steps performed by a user equipment according to a first embodiment; [Figure 20] 1 is a flow chart illustrating exemplary steps performed by a network node according to a first embodiment. [Figure 21] 1 is a flow chart illustrating exemplary steps performed by a user equipment according to a second embodiment; [Figure 22] 1 is a flow chart illustrating exemplary steps performed by a network node according to a second embodiment. [Figure 23] 1 illustrates an example embodiment of receiving a paging message that includes a notification of an SDT. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <5G NR system architecture and protocol stack> 3GPP is working on the next release of fifth-generation cellular technology (known simply as "5G"), which includes the development of a new radio access technology (NR) that will operate in frequencies up to 100 GHz. The first version of the 5G standard will be completed at the end of 2017, which will allow smartphones compliant with the 5G NR standard to proceed to testing and commercial deployment.

[0011] In particular, the overall system architecture envisages an NG-RAN (Next Generation - Radio Access Network) with gNBs terminating NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocols. The gNBs are interconnected with each other by an Xn interface. The gNBs are also connected to an NGC (Next Generation Core) by a Next Generation (NG) interface, more specifically to an AMF (Access and Mobility Management Function) (e.g., a specific core entity that runs the AMF) by an NG-C interface, and to a UPF (User Plane Function) (e.g., a specific core entity that runs the UPF) by an NG-U interface. The NG-RAN architecture is shown in Figure 1 (see, for example, Section 4 of Non-Patent Document 1).

[0012] The user plane protocol stack in NR (see, for example, Section 4.4.1 of Non-Patent Document 1) includes a PDCP (Packet Data Convergence Protocol, see Section 6.4 of Non-Patent Document 1) sublayer, an RLC (Radio Link Control, see Section 6.3 of Non-Patent Document 1) sublayer, and a MAC (Medium Access Control, see Section 6.2 of Non-Patent Document 1) sublayer, which terminate at the gNB on the network side. In addition, a new sublayer (SDAP, Service Data Adaptation Protocol) of the access stratum (AS) is introduced on top of PDCP (see, for example, Section 6.5 of Non-Patent Document 1). A control plane protocol stack is also defined in NR (see, for example, Section 4.4.2 of Non-Patent Document 1). An overview of the functions of Layer 2 is given in Section 6 of Non-Patent Document 1. The functions of the PDCP, RLC, and MAC sublayers are respectively described in Sections 6.4, 6.3, and 6.2 of 3GPP TS 2.0. The functions of the RRC layer are described in Section 7 of 3GPP TS 2.0.

[0013] For example, the Medium-Access-Control (MAC) layer handles scheduling and scheduling-related functions, including multiplexing of logical channels, as well as handling of various numerologies.

[0014] The physical layer (PHY) is responsible for, for example, coding, PHY HARQ processing, modulation, multi-antenna processing, and mapping of signals to appropriate physical time-frequency resources. The physical layer also handles mapping of transport channels to physical channels. The physical layer provides services to the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for transmission of a particular transport channel, and each transport channel is mapped to a corresponding physical channel. For example, the physical channels are PRACH (Physical Random Access Channel), PUSCH (Physical Uplink Shared Channel), and PUCCH (Physical Uplink Control Channel) for the uplink, and PDSCH (Physical Downlink Shared Channel), PDCCH (Physical Downlink Control Channel), and PBCH (Physical Broadcast Channel) for the downlink.

[0015] NR use cases / deployment scenarios include enhanced Mobile Broadband (eMBB), ultra-reliable and low latency communications (URLLC), and massive machine type communications (mMTC), which have diverse requirements in terms of data rates, latency, and coverage. For example, eMBB is expected to support peak data rates (20 Gbps downlink and 10 Gbps uplink) and user-perceived data rates that are on the order of three times higher than those offered by IMT-Advanced. In contrast, URLLC has more stringent requirements, including extremely low latency (user plane latency of 0.5 ms for UL and DL, respectively) and high reliability (1-10 Mbps within 1 ms). -5) and mMTC requires high connection density (1 km 2 1,000,000 devices per second), wide coverage in harsh environments, and extremely long battery life (15 years) to lower device costs may be preferably required.

[0016] Thus, an OFDM numerology (e.g., subcarrier spacing, OFDM symbol duration, cyclic prefix (CP) duration, number of symbols per scheduling interval) suitable for one use case may not work well for another use case. For example, low latency services may preferably require a shorter symbol duration (and therefore a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also referred to as TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP duration than scenarios with small delay spreads. To maintain a comparable CP overhead, the subcarrier spacing should be optimized depending on the delay spread. In NR, more than one value of subcarrier spacing may be supported. Thus, currently, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, ... are considered. The symbol duration T u and the subcarrier spacing Δf is expressed by the formula (Δf=1 / T u ), as in LTE systems, the term "resource element" can be used to denote the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0017] In the new radio system 5G-NR, for each numerology and carrier, a resource grid of subcarriers and OFDM symbols is defined for both the uplink and the downlink. Each element within the resource grid is called a resource element and is identified based on a frequency index in the frequency domain and a symbol position in the time domain (see Version 15.6.0 of Non-Patent Document 2). For example, downlink transmission and uplink transmission are organized into frames with a duration of 10 ms, and each frame is composed of 10 subframes with a duration of 1 ms each. In an implementation of 5G NR, the number of consecutive OFDM symbols per subframe depends on the setting of the subcarrier spacing. For example, in the case of a subcarrier spacing of 15 kHz, one subframe has 14 OFDM symbols (similar to an LTE-compliant implementation assuming a normal cyclic prefix). On the other hand, in the case of a subcarrier spacing of 30 kHz, one subframe has two slots, and each slot contains 14 OFDM symbols.

[0018] The new numerology (subcarrier spacing and symbol length) of NR supports multiple different types of subcarrier spacings labeled by the parameter μ compared to the numerology of LTE (in LTE, there is only a subcarrier spacing of 15 kHz corresponding to μ = 0). The types of NR new numerology are summarized in Version 15.7.0 of Non-Patent Document 2.

[0019] <Function Split of 5G NR between NG-RAN and 5GC> Figure 2 shows the split of functions between NG-RAN and 5GC. The logical nodes of NG-RAN are gNB or ng-eNB. The logical nodes of 5GC are AMF, UPF, and SMF.

[0020] In particular, gNB and ng-eNB handle the following main functions. - Radio Resource Management functions such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, dynamic resource allocation (scheduling) to UEs in both uplink and downlink directions - IP header compression, encryption, and integrity protection of data - Selection of AMF at UE attach time when routing to AMF cannot be determined from information provided by the UE - Routing of user plane data to the UPF - Routing control plane information to AMF - Establishing and releasing connections - Scheduling and sending paging messages - Scheduling and transmission of system broadcast information (sent from AMF or OAM) - Configuring measurements and measurement reporting for mobility and scheduling - Transport-level packet marking in the uplink - Session Management - Network slicing support - QoS flow management and mapping to data radio bearers - Support for UEs in RRC_INACTIVE state - NAS message delivery function - Wireless Access Network Sharing - Dual Connectivity - Tight interworking between NR and E-UTRA

[0021] The Access and Mobility Management Function (AMF) handles the following main functions: - Termination of Non-Access Stratum (NAS) signalling - NAS signaling security - Access Stratum (AS) security control - Core Network (CN) inter-node signaling for mobility between 3GPP access networks - Reachability for idle mode UEs (including control and execution of paging retransmissions) - Registration Area Management - Support for intra-system and inter-system mobility - Access Authentication - Access authentication, including roaming rights checks - Mobility management controls (subscriptions and policies) - Network slicing support - Selection of Session Management Function (SMF)

[0022] Furthermore, the User Plane Function (UPF) handles the following main functions: - Anchor points for intra-RAT / inter-RAT mobility (when applicable) - External PDU session points for interconnection with data networks - Packet routing and forwarding - User plane part of packet inspection and policy rule enforcement - Traffic usage reports - an uplink classifier to support routing of traffic flows to the data network; - Branching points to support multi-homed PDU sessions - User plane QoS processing (e.g. packet filtering, gating, UL / DL rate enforcement) - Verification of uplink traffic (mapping from SDF to QoS flow) - Buffering of downlink packets and triggering of downlink data notification

[0023] Finally, the Session Management Function (SMF) processes the following main functions. - Session management - Allocation and management of UE IP addresses - Selection and control of the UP function - Configuration of traffic steering in the User Plane Function (UPF) to route traffic to the correct destination - Policy enforcement and QoS control part - Downlink data notification

[0024] <Procedures for establishment and reconfiguration of RRC connection> Figure 3 shows the interaction among the UE, gNB, and AMF (5GC entity) in the NAS part when the UE transitions from RRC_IDLE to RRC_CONNECTED (see Non-Patent Document 1).

[0025] RRC is a higher layer signaling (protocol) used for the configuration of the UE and the gNB. In particular, in this transition, the AMF creates UE context data (including, for example, PDU session context, security keys, UE radio capabilities, UE security capabilities, etc.) and sends it to the gNB via an INITIAL CONTEXT SETUP REQUEST. The gNB then activates AS security with the UE, which is performed by the gNB sending a SecurityModeCommand message to the UE and the UE responding with a SecurityModeComplete message to the gNB. The gNB then performs a reconfiguration to establish a signaling radio bearer 2 (SRB2) and a data radio bearer (DRB), which is performed by the gNB sending an RRCReconfiguration message to the UE and the gNB receiving an RRCReconfigurationComplete from the UE in response. In the case of a signaling-only connection, these steps related to RRCReconfiguration are skipped since SRB2 and DRB are not established. Finally, the gNB informs the AMF that the establishment procedure is complete via an INITIAL CONTEXT SETUP RESPONSE.

[0026] Therefore, the present disclosure provides a fifth generation core (5GC) entity (e.g., AMF, SMF, etc.) having a control circuit that, in operation, establishes a next generation (NG) connection with a gNodeB, such that a signaling radio bearer is established between the gNodeB and a user equipment (UE), and a transmitter that, in operation, transmits an initial context setup message to the gNodeB via the NG connection. In particular, the gNodeB transmits radio resource control (RRC) signaling including a resource allocation configuration information element to the UE via the signaling radio bearer. The UE then performs uplink transmission or downlink reception based on the resource allocation configuration.

[0027] <IMT usage scenarios after 2020> Figure 4 shows some of the use cases for 5G NR. The 3rd generation partnership project new radio (3GPP NR) considers three use cases envisaged to support a wide variety of services and applications by IMT-2020. The specifications for phase 1 of enhanced mobile broadband (eMBB) have been finalized. Current and upcoming work includes standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC), in addition to further extending eMBB support. Figure 4 shows some examples of IMT usage scenarios envisaged for 2020 and beyond (see, for example, Figure 2 in Non-Patent Document 3).

[0028] URLLC use cases have stringent requirements on capabilities such as throughput, latency and availability, and are envisioned as one of the enablers of future vertical applications such as wireless control of industrial manufacturing or production processes, remote medical surgery, power distribution automation in smart grids, and transportation safety. The ultra-high reliability of URLLC is supported by identifying technologies to meet the requirements set by NR URLLC in Release 15. For NR URLLC in Release 15, key requirements include a user plane target latency of 0.5 ms for UL (uplink) and 0.5 ms for DL ​​(downlink). A typical URLLC requirement for a single transmission of a packet is a BLER (block error rate) of 1E-5 for a packet size of 32 bytes with a user plane latency of 1 ms.

[0029] From the physical layer perspective, there are several possible ways to improve reliability. Current scope for improving reliability includes defining a separate CQI table for URLLC, a more compact Downlink Control Information (DCI) format, PDCCH repetition, etc. However, as NR becomes more stable and developed (a key requirement for NR URLLC), the scope for achieving ultra-high reliability may increase. Specific use cases for NR URLLC in Release 15 include augmented reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0030] Furthermore, technology enhancements targeted by NR URLLC target latency improvement and reliability improvement. Technology enhancements for latency improvement include configurable numerology, non-slot-based scheduling with flexible mapping, grant-free (configured grant) uplink, slot-level repetition of data channel, and preemption for downlink. Preemption means that a transmission for which resources are already allocated is aborted and the already allocated resources are used for another transmission with smaller latency / higher priority requirement requested later. Thus, an already granted transmission is preempted by a later transmission. Preemption applies regardless of the specific service type. For example, a transmission of service type A (URLLC) can be preempted by a transmission of service type B (eMBB, etc.). Technology enhancements for reliability improvement include dedicated CQI / MCS tables for a target BLER of 1E-5.

[0031] The mMTC (Massive Machine Type Communication) use case is characterized by a very large number of connected devices transmitting relatively small amounts of data that are generally not sensitive to latency. The devices need to be low cost and have extremely long battery life. From an NR perspective, utilizing very narrow bandwidth portions is one possible solution to achieve power savings from the UE perspective to enable long battery life.

[0032] As mentioned above, it is expected that the range of reliability in NR will increase. One key requirement for all cases, especially for URLLC and mMTC, is high or ultra-high reliability. Several mechanisms can be considered to improve reliability from a radio perspective and from a network perspective. In general, there are several key areas that can help improve reliability. These areas include compact control channel information, data channel / control channel repetition, and diversity related to frequency, time, and / or spatial domains. These areas are generally applicable to reliability, regardless of the specific communication scenario.

[0033] For NR URLLC, further use cases with more stringent requirements have been identified, e.g. in factory automation, the transport industry and power supply. The more stringent requirements include higher reliability (up to 10 times faster) depending on the use case. -6 These include: high-speed (level 1), higher availability, packet sizes up to 256 bytes, time synchronization on the order of a few microseconds (values ​​range from 1 to a few microseconds depending on the frequency range), and short latency on the order of 0.5 to 1 ms (the target latency for the user plane in particular is 0.5 ms).

[0034] Furthermore, in the case of NR URLLC, several technical enhancements have been recognized from the perspective of the physical layer. In particular, enhancements related to PDCCH (Physical Downlink Control Channel) include compact DCI, repetition of PDCCH, and increased PDCCH monitoring. Also, enhancements related to UCI (Uplink Control Information) include enhancements of HARQ (Hybrid Automatic Repeat Request) and CSI feedback. In addition, enhancements of PUSCH related to mini-slot level hopping and retransmission / repetition have also been recognized. The term "mini-slot" means a transmission time interval (TTI: Transmission Time Interval) that contains a smaller number of symbols than a slot (a slot contains 14 symbols).

[0035] <QoS Control> The 5G QoS (Quality of Service) model is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (GBR QoS flows) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flows). Therefore, at the NAS level, a QoS flow is the finest granularity of QoS differentiation in a PDU session. A QoS flow is identified within a PDU session by a QoS flow ID (QFI) that is transmitted within a capsule header through the NG-U interface.

[0036] The 5GC establishes one or more PDU sessions for each UE. The NG-RAN establishes at least one Data Radio Bearer (DRB) for each UE with the PDU sessions, and can then configure additional DRBs for the QoS flows of the PDU sessions (NG-RAN decides when to do so), e.g. as described above with reference to FIG. 3. The NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filters in the UE and 5GC associate UL and DL packets with QoS flows, and AS-level mapping rules in the UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0037] Figure 5 shows the non-roaming reference architecture of 5G NR (see section 4.23 of non-patent document 5). Application Functions (AFs) (e.g., external application servers handling 5G services exemplarily described in Figure 4) interact with the 3GPP Core Network to provide services. For example, they support application influence on traffic routing, access Network Exposure Functions (NEFs), or interact with a policy framework (see Policy Control Function (PCF)) for policy control (e.g., QoS control). Based on the operator's deployment, application functions (AFs) that are deemed trusted by the operator can be allowed to interact directly with the relevant network functions. Application functions (AFs) that are not allowed by the operator to directly access network functions interact with the relevant network functions using an external exposure framework via the NEF.

[0038] Figure 5 shows further functional units of the 5G architecture: Network Slice Selection Function (NSSF), Network Repository Function (NRF), Unified Data Management (UDM), Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Session Management Function (SMF), and Data Network (DN) (e.g. operator's services, internet access or third party services). All or part of the core network functions and application services may be located and executed in a cloud computing environment.

[0039] Therefore, the present disclosure provides an application server (e.g., an AF in a 5G architecture) having a transmitter unit that, during operation, sends a request including QoS requirements for at least one of a URLLC service, an eMMB service, and an mMTC service to at least one of the 5GC functions (e.g., NEF, AMF, SMF, PCF, UPF, etc.) to establish a PDU session including a radio bearer between a gNodeB and a UE in accordance with the QoS requirements, and a control circuit that, during operation, executes said service using the established PDU session.

[0040] <Control signal> In the present disclosure, the downlink control signal (information) according to the present disclosure may be a signal (information) transmitted via a PDCCH of a physical layer, or may be a signal (information) transmitted via a MAC Control Element (CE) of a higher layer or an RRC. The downlink control signal may be a predefined signal (information).

[0041] The uplink control signal (information) according to the present disclosure may be a signal (information) transmitted via a PUCCH of a physical layer, or may be a signal (information) transmitted via a MAC CE of a higher layer or an RRC. Also, the uplink control signal may be a predefined signal (information). The uplink control signal may be uplink control information (UCI), first stage sidelink control information (SCI), or second stage SCI.

[0042] <Device> A terminal or user terminal or user device or mobile station or mobile node is called user equipment (UE) in LTE and NR. A user equipment (UE) may be a mobile device or communication device, such as a wireless telephone, a smartphone, a tablet computer, or a USB (Universal Serial Bus) stick with user equipment functionality. However, the term mobile device is not limited thereto, and in general, a repeater may also have such mobile device functionality, and a mobile device may act as a repeater. For example, a terminal is a physical entity (physical node) in a communication network. Furthermore, a communication device may be any machine-type communication device, such as an IoT device, etc. A node may have several functional entities. A functional entity refers to a software or hardware module that realizes and / or provides a given set of functions to other functional entities of the same or other nodes or networks. A node may have one or more interfaces that connect the node to communication facilities or media over which the node can communicate. Similarly, a network entity may have logical interfaces that connect a functional entity to communication facilities or media over which it can communicate with other functional entities or correspondent nodes.

[0043] <Base station> In the present disclosure, the base station may be, for example, a Transmission Reception Point (TRP), a cluster head, an access point, a Remote Radio Head (RRH), an eNodeB (eNB), a gNodeB (gNB), a Base Station (BS), a Base Transceiver Station (BTS), a base unit, or a gateway. In addition, in sidelink communication, a terminal may be used instead of the base station. The base station may be a relay device that relays communication between an upper node and a terminal.

[0044] The base station may be a roadside unit. The base station may be, for example, a scheduling node or a network node forming part of a network for providing services to terminals. In particular, the base station may provide radio access to the terminals. The communication between the terminals and the base station is generally standardized and may be defined by different layers such as PHY, MAC, and RRC. In LTE and NR, the air interface protocol stack includes a physical layer, a medium access (MAC) layer, and an upper layer. The control plane is provided with the radio resource control protocol, which is an upper layer protocol. Through the RRC, the base station may control the configuration of the terminals, and the terminals may communicate with the base station to perform control tasks such as establishing and modifying connections and bearers, measurements, and other functions. The terminology used in LTE is eNB (or eNodeB), while the terminology currently used in 5G NR is gNB.

[0045] The term "base station" or "radio base station" refers in this specification to a physical entity in a communication network. A base station, like a mobile station, may have several functional entities. A functional entity refers to a software or hardware module that performs and / or provides a given set of functions for another functional entity of the same node or another node or network. A physical entity performs several control tasks related to a communication device, including one or more of scheduling and configuration. It should be noted that the functions of a base station and the functions of a communication device may be integrated in one device. For example, a mobile terminal may further perform the functions of a base station for another terminal. The terminology used in LTE is eNB (or eNodeB), while the terminology currently used in 5G NR is gNB.

[0046] <Uplink / Downlink / Sidelink> The present disclosure may be applied to any of the uplink, downlink, and sidelink.

[0047] For example, the present disclosure may be applied to the uplink PUSCH, PUCCH, and PRACH, the downlink PDSCH, PDCCH, and PBCH, and the sidelink PSSCH (Physical Sidelink Shared Channel), PSCCH (Physical Sidelink Control Channel), and PSBCH (Physical Sidelink Broadcast Channel).

[0048] The PDCCH, PDSCH, PUSCH, and PUCCH are examples of a downlink control channel, a downlink data channel, an uplink data channel, and an uplink control channel, respectively. The PSCCH and PSSCH are examples of a sidelink control channel and a sidelink data channel, respectively. The PBCH and PSBCH are examples of a broadcast channel, and the PRACH is an example of a random access channel.

[0049] <Data Channel / Control Channel> The present disclosure may be applied to both data channels and control channels. The channels in the present disclosure may be replaced with data channels including PDSCH, PUSCH, and PSSCH, and / or control channels including PDCCH, PUCCH, PBCH, PSCCH, and PSBCH.

[0050] <Reference signal> In this disclosure, a reference signal is a signal known to both a base station and a mobile station, and each reference signal may be referred to as a reference signal (RS) or a pilot signal. A reference signal may be any of a DMRS, a Channel State Information - Reference Signal (CSI-RS), a Tracking Reference Signal (TRS), a Phase Tracking Reference Signal (PTRS), a Cell-specific Reference Signal (CRS), and a Sounding Reference Signal (SRS).

[0051] <time interval> In the present disclosure, the time resource unit is not limited to one or a combination of slots and symbols, and may be a time resource unit such as a frame, a superframe, a subframe, a slot, a subslot of a time slot, a minislot, or a symbol, an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier-Frequency Division Multiplexing Access (SC-FDMA) symbol, or other time resource unit. The number of symbols included in one slot is not limited to the number of symbols exemplified in the above-mentioned embodiment, and may be other numbers of symbols.

[0052] <Frequency band> The present disclosure may apply to both licensed and unlicensed bands.

[0053] <Communication> The present disclosure may be applied to any of communication between a base station and a terminal (Uu link communication), communication between terminals (sidelink communication), and V2X (Vehicle to Everything) communication. The channels in the present disclosure may be rephrased as PSCCH, PSSCH, physical sidelink feedback channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, and PBCH.

[0054] The present disclosure can also be applied to a terrestrial network or a non-terrestrial network (NTN) using a satellite or a high altitude pseudo satellite (HAPS). The present disclosure can also be applied to a terrestrial network with a large cell size and a large delay compared to a symbol length or a slot length, such as an ultra-wideband transmission network.

[0055] <Antenna port> An antenna port refers to a logical antenna (antenna group) formed from one or more physical antennas. That is, an antenna port does not necessarily refer to one physical antenna, but may refer to an array antenna consisting of multiple antennas. For example, the number of physical antennas constituting an antenna port is not defined, and instead, an antenna port is defined as the smallest unit that a terminal is allowed to transmit a reference signal. An antenna port may also be defined as the smallest unit for multiplication of a precoding vector weighting.

[0056] <Downlink control channel monitoring, PDCCH, DCI> Many of the functions performed by a UE include monitoring a downlink control channel (e.g., the PDCCH, see 3GPP TS 2013-011066, version 15.6.0, section 5.2.3) for example to receive specific control information or data intended for the UE.

[0057] Below is a non-exhaustive list of such features: - Paging message monitoring function, - System information acquisition function, - signalling supervision operation in discontinuous reception (DRX) functionality; - inactivity monitoring operation in the discontinuous reception (DRX) function; - receiving a random access response in a random access function; - Packet Data Convergence Protocol (PDCP) layer reordering function

[0058] As described above, the PDCCH is monitored by the UE to identify and receive information intended for the UE, such as control information and user traffic (e.g., DCI on the PDCCH, user data on the PDSCH indicated by the PDCCH).

[0059] Control information in the downlink (which can be referred to as downlink control information, DCI) has the same purpose in 5G NR as DCI in LTE, that is, for example, a special set of control information for scheduling a downlink data channel (e.g., PDSCH) or an uplink data channel (e.g., PUSCH).

[0060] In 5G NR, many different DCI formats have already been defined (see Non-Patent Document 6, Version 15.6.0, Section 7.3.1).

[0061] These DCI formats represent predetermined formats in which respective information is formed and transmitted. In particular, DCI formats 0_1 and 1_1 are used for scheduling PUSCH and PDSCH in one cell, respectively.

[0062] PDCCH monitoring in each of these functions serves a specific purpose and is thus initiated for that purpose. PDCCH monitoring is usually controlled at least based on a timer that the UE operates. The timer has the purpose of controlling PDCCH monitoring, for example, limiting the maximum time duration for which the UE monitors the PDCCH. For example, the UE does not need to monitor the PDCCH indefinitely and can stop monitoring after a certain time to save power.

[0063] As described above, one of the purposes of DCI in the PDCCH is to dynamically schedule resources in the downlink, uplink, or sidelink. In particular, some formats of DCI are provided to convey a notification of resource allocation (RA) for a data channel to a specific user. The resource allocation can include the specification of resources in the frequency domain and / or time domain.

[0064] <UE identification information> RNTI stands for Radio Network Temporary Identifier. For example, RNTI can be used to distinguish and identify UEs in a radio cell. In addition, RNTI can also identify a specific radio channel, a group of UEs in case of paging, a group of UEs for which power control is issued by the eNB, and system information transmitted by the 5G gNB to all UEs. In 5G NR, a number of different identification information for UEs are defined, some of which are shown in the following table (see 3GPP TS 2013-010303, rev. 15.8.0, section 7.1):

[0065] [Table 1]

[0066] Besides the above RNTIs, further IDs are envisaged, such as Inactive-RNTI (I-RNTI) (see, for example, 3GPP TS 2013-010363, ed. 15.8.0, section 6.3.2). The Inactive-RNTI is used by the UE in the process of identifying and locating a UE in RRC_INACTIVE state and, for example, its suspended UE context. According to one implementation, the network assigns the I-RNTI when the UE transitions to RRC_INACTIVE state (from RRC_CONNECTED) (for example, as part of the RRCRelease message in SuspendConfig). There are two types of I-RNTI: full I-RNTI and short I-RNTI. The network can inform the UE which I-RNTI to use when resuming the connection (for example, as part of SIB1, System Information Block 1). Note that the full I-RNTI is a bit string of length 40 bits and the short I-RNTI is a bit string of length 24 bits.

[0067] <Random access procedure> Similar to LTE, 5G NR provides a Random Access Channel (RACH) procedure (or simply a random access procedure). For example, the RACH procedure can be used by a UE to access a discovered cell. The RACH procedure can also be used, for example, to: During handover, when establishing synchronization to a new cell, To re-establish uplink synchronization to the current cell if synchronization is lost due to a long period without uplink transmissions from the device. If a dedicated scheduling request resource is not configured for the device, It can also be used in other contexts within NR.

[0068] There are many events that can trigger the UE to perform a random access procedure (see 3GPP TS 2013-01033, section 9.2.6), including: - Initial access from RRC_IDLE - RRC connection re-establishment procedure - DL data or UL data arrives at RRC_CONNECTED when the UL synchronization state is "asynchronous" - UL data arrives during RRC_CONNECTED when no PUCCH resources are available for SR (scheduling request) - SR Failure - Required by RRC during synchronous reconfiguration (e.g. handover) - Transition from RRC_INACTIVE - Establishing time alignment of secondary TAGs - Other SI requirements (see section 7.3) - Beam failure recovery - Continuous UL LBT failures on SpCell Triggered by

[0069] A mobile terminal can be scheduled for uplink transmission if its uplink transmission is time synchronized. Thus, the Random Access Channel (RACH) procedure serves as an interface between unsynchronized mobile terminals (UEs) and orthogonal transmission of uplink radio access. Random access is used, for example, to achieve uplink time synchronization for user equipment that has not yet acquired or lost uplink synchronization. Once the user equipment acquires uplink synchronization, the base station can schedule uplink transmission resources for the user equipment. One scenario related to random access is when a user equipment in RRC_CONNECTED state hands over from a current serving cell to a new target cell and performs a random access procedure to achieve uplink time synchronization in the target cell.

[0070] There are two types of random access procedures: those that allow access on a contention-based basis (i.e., inherently with the risk of collisions) and those that allow access on a contention-free basis (without contention). An exemplary definition of a random access procedure is given in 3GPP TS 2.0, version 16.1.0, section 5.1.

[0071] The RACH procedure will now be described in more detail with reference to Figures 6 and 7. In the following, the contention-based random access procedure will be described in more detail with reference to Figure 6. This procedure consists of four "steps" and can therefore be referred to as, for example, a four-step RACH procedure. First, the user equipment transmits a random access preamble to the base station on the physical random access channel (PRACH) (i.e., message 1 of the RACH procedure). After detecting the RACH preamble, the base station transmits a Random Access Response (RAR) message (message 2 of the RACH procedure) on the PDSCH (Physical Downlink Shared Channel) that is addressed on the PDCCH using the (random access) RA-RNTI that identifies the time frequency and slot where the preamble was detected. If multiple user equipments transmit the same RACH preamble on the same PRACH resource (also called collision), they will receive the same random access response message. The RAR message may convey the detected RACH preamble, a Timing Alignment Command (TA command) for synchronization of subsequent uplink transmissions based on the timing of the received preamble, an initial uplink resource allocation (grant) for sending the first scheduled transmission, and the allocation of a Temporary Cell Radio Network Temporary Identifier (T-CRNTI), which is used by the base station as the address of the mobile whose RACH preamble was detected until the RACH procedure is finished, since at this point the base station does not know the "real" identity of the mobile.

[0072] The user equipment monitors the PDCCH to receive a random access response message within a predefined time window (e.g., called the RAR reception window), which may be set by the base station. In response to the RAR message received from the base station, the user equipment transmits a first scheduled uplink transmission on the radio resources allocated by the grant in the random access response. This scheduled uplink transmission carries the actual message with a specific function, such as an RRC connection request, an RRC resume request, or a buffer status report.

[0073] If a preamble collision occurs in the first message of the RACH procedure, i.e. multiple user equipments transmit the same preamble on the same PRACH resource, the colliding user equipments receive the same T-CRNTI in the random access response and also collide on the same uplink resource when transmitting scheduled transmissions in the third step of the RACH procedure. If the scheduled transmission from one user equipment is successfully decoded by the base station, the contention remains unresolved for the other user equipments. To resolve this type of contention, the base station transmits a contention resolution message (fourth message) addressed to the C-RNTI or temporary C-RNTI. This ends the procedure.

[0074] Figure 7 shows a contention-free random access procedure, which is simplified compared to the contention-based random access procedure. In a first step, the base station provides the user equipment with a dedicated preamble to be used for random access, so that there is no risk of collision (i.e., multiple user equipments transmitting the same preamble). Thus, the user equipment transmits the preamble signaled by the base station in the uplink on the PRACH resource. Since the contention-free random access avoids the case where multiple UEs transmit the same preamble, the contention-free random access procedure is essentially terminated after the random access response is successfully received by the UE.

[0075] 3GPP also defines a two-step (contention-based) RACH procedure for 5G NR, in which message 1 (called MsgA), corresponding to messages 1 and 3 in the four-step LTE / NR RACH procedure, is transmitted first. MsgA of the two-step RACH type contains a preamble on the physical random access channel (PRACH) and a payload on the physical uplink shared channel (PUSCH). After transmitting MsgA, the UE monitors for a response from the gNB within a configured time window. The gNB responds with message 2 (called MsgB), corresponding to messages 2 and 4 in the four-step LTE / NR RACH procedure. This MsgB may contain, for example, a successful random access response (RAR), a fallback RAR, and optionally backoff notification information. If a successful RAR is received and the contention is successfully resolved, the UE terminates the random access procedure. On the other hand, if the UE receives fallback RAR in MsgB, it performs transmission of message 3 (similar to the four-step RACH procedure) and monitors contention resolution. Some further exemplary assumptions are made for the two-step RACH procedure, e.g., after the UE determines the RACH type (e.g., two-step RACH), it keeps retrying the same RACH type until it fails. However, it is also possible that the UE switches to the four-step RACH procedure after retrying transmission of MsgA a certain number of times.

[0076] Furthermore, the network may semi-statically determine the mutually exclusive radio resources used to perform the two-step RACH procedure and the four-step RACH procedure. The radio resources used for transmitting the first message in the RACH procedure include at least a RACH occasion and a preamble. For example, in the two-step RACH procedure, the first message MsgA uses not only the PRACH resource (e.g., the RACH occasion and the preamble) but also the associated PUSCH resource.

[0077] Generally, for the RACH preamble, refer to, for example, Non-Patent Document 2, "Table 6.3.3.2-2: Random access configurations for FR1 and paired spectrum / supplementary uplink" in Release 16.2.0, and Section 6.3.3.2, "Mapping to physical resources".

[0078] <RRC state (RRC_Connected, RRC_Inactive, RRC Idle)> In LTE, the RRC state machine consists of only two states: the RRC idle state (characterized mainly by high power savings, UE autonomous mobility, and no established connection between the UE and the core network), and the RRC connected state. In the RRC connected state, while mobility is controlled by the network to support lossless service continuity, the UE can transmit user plane data. In 5G NR, the RRC state machine related to LTE can be extended by the inactive state (see, for example, Non-Patent Document 8, Release 16.1.0, Figures 4.2.1-1 and 4.2.1-2), as described below.

[0079] In NR 5G RRC (refer to Section 4 of Non-Patent Document 8), the idle state, inactive state, and connected state (specifically, RRC Idle, RRC Inactive, and RRC Connected) are supported. When the RRC connection is established, the UE is in either the RRC_CONNECTED state or the RRC_INACTIVE state. Otherwise, i.e., when the RRC connection is not established, the UE is in the RRC_IDLE state. As shown in Figure 8, the following state transitions are possible. For example, from RRC_IDLE to RRC_CONNECTED, following the "Connection Establishment" procedure. For example, from RRC_CONNECTED to RRC_IDLE, following the "Connection Release" procedure. For example, from RRC_CONNECTED to RRC_INACTIVE following the "Connection release due to interruption" procedure. For example, following the "restart connection" procedure from RRC_INACTIVE to RRC_CONNECTED For example, from RRC_INACTIVE to RRC_IDLE (unidirectional) following the "Connection Release" procedure.

[0080] A new RRC state, RRC Inactive, has been defined for 5G 3GPP new radio technologies such as eMBB (enhanced Mobile Broadband), mMTC (massive Machine Type Communications), URLLC (Ultra-Reliable and Low-Latency Communications) to provide benefits when supporting a wide range of services with very different requirements in terms of signaling, power saving, latency, etc. The new RRC Inactive state is therefore designed to minimize signaling, power consumption and resource costs in the radio access network and core network, while still allowing, for example, data transfer to be initiated with low latency.

[0081] According to an exemplary 5G NR implementation, these different states are characterized as follows (see section 4.2.1 of 3GPP TS 2011-010113):

[0082] "RRC_IDLE: - UE-specific DRX can be configured by higher layers - UE controlled mobility based on network configuration - UE - monitor short messages sent using the P-RNTI over the DCI (see section 6.5); - Monitoring a paging channel in CN paging using 5G-S-TMSI; - Perform neighboring cell measurements and cell (re)selection - Can retrieve system information and send SI requests (if configured) - Perform logging of available measurements along with location and time for UEs for which measurements are configured to be logged.

[0083] - RRC_INACTIVE: UE-specific DRX can be configured by higher layers or by the RRC layer - UE controlled mobility based on network configuration - The UE stores the UE Inactive AS context. - RAN-based notification area is configured by the RRC layer - UE - monitor short messages sent using the P-RNTI over the DCI (see section 6.5); - Monitor the paging channel in CN paging using 5G-S-TMSI and RAN paging using full I-RNTI (full-RNTI) - Perform neighboring cell measurements and cell (re)selection - RAN-based notification area updates are performed periodically and when moving outside the configured RAN-based notification area - Can retrieve system information and send SI requests (if configured) - Perform logging of available measurements along with location and time for UEs for which measurements are configured to be logged.

[0084] - RRC_CONNECTED: - The UE stores the AS context - Forwarding unicast data to and from the UE - Lower layers can configure UE-specific DRX for the UE - For UEs supporting CA, use one or more Scells aggregated with an SpCell to increase bandwidth. - For UEs that support DC, use one SCG aggregated with an MCG to increase bandwidth - Network controlled mobility within NR and to / from E-UTRA - UE - if configured, monitor Short Messages sent using the P-RNTI over the DCI (see section 6.5); - monitoring a control channel associated with the shared data channel to determine whether data is scheduled; - Providing channel quality and feedback information - Perform neighbor cell measurements and measurement reporting - Get system information - Perform immediate MDT measurements with available location reports."

[0085] According to the characteristics of the RRC Inactive state, the connection (both user plane and control plane) with the RAN and the core network is maintained for the inactive UE. More specifically, in RRC Inactive, the connection still exists but is interrupted, in other words, the connection is no longer valid. In NR, when the UE is in the RRC_Inactive state, the NG (Next Generation) signaling is kept alive between the gNB and the AMF. The GTP-U (GPRS Tunneling Protocol User Plane) also remains alive between the gNB and the UPF. The UE context is stored in the UE and the gNB. In contrast, in the RRC Connected state, the connection exists and is active in the sense that it is used, for example, for data transmission. In the RRC Idle state, the UE does not have an RRC connection with the RAN and the core network, which also means that, for example, the radio base station does not have the context of the UE, e.g., does not know the identity of the UE, and does not have security parameters for the UE to be able to correctly decode data transmitted by the UE (security, for example, ensures the integrity of the transmitted data). The UE's context may be available in the core network, but must first be obtained by the radio base station.

[0086] A UE in RRC_IDLE or RRC_CONNECTED waits to receive a paging message. Such a paging mechanism includes logical and transport channels for paging. The Paging Control Channel (PCCH) is a logical downlink channel used for transmitting paging information from the network to the device. The Paging Channel (PCH) is a transport channel used to carry paging information from the PCCH logical channel. The PCH supports Discontinuous Reception (DRX), which allows the UE to save battery power by waking up at specific times to receive the PCH. The PCH is mapped to the PDSCH in NR.

[0087] Furthermore, the paging mechanism (e.g., also called notification mechanism) for user equipment in a radio cell is based on so-called Radio Access Network (RAN)-based Notification Area (RNA for short). The radio access network should be aware of the current RNA in which the user equipment is located, and the user equipment can assist the gNB to track the UE moving between different RNAs. The RNA can be UE-specific.

[0088] In the following, an example of an RRC resumption procedure (see section 5.3.13 of 3GPP TS 21.2006) for a UE to transition from RRC_Inactive to RRC_Connected state is described with reference to Fig. 9. The purpose of this procedure is to re-start a suspended RRC connection, which may include the resumption of signalling and data radio bearers.

[0089] In this procedure, either an RRCResumeRequest message or an RRCResumeRequest1 message can be sent. When sending the RRCResumeRequest message, a short I-RNTI (e.g., a truncated I-RNTI) is used as the UE's identity (exemplarily called "resumeIdentity"). When sending the RRCResumeRequest1 message, a full I-RNTI is used as the UE's identity (exemplarily called "resumeIdentity"). The UE checks the notification information "useFullResumeID" in SIB1 and decides to send either an RRCResumeRequest message or an RRCResumeRequest1 message. If "useFullResumeID" indicates "true", the UE sends the RRCResumeRequest1 message using the full I-RNTI, otherwise the UE sends the RRCResumeRequest using the short I-RNTI. The actions performed by the UE during the RRC resumption procedure (see section 5.3.13.4 of 3GPP TS 2013-010112) include resuming SRB2 and all DRBs that were suspended when the UE transitioned to the RRC Inactive state (see the release procedure below).

[0090] The RRC Resumption procedure can also be used to perform an RNA update when the UE moves outside the configured RNA. In this case, the network sends RRCRelease instead of RRCResume in response to the RRCResumeRequest / RRCResumeRequest1 message as shown in Figure 10. The UE remains in RRC_INACTIVE after receiving the RRCRelease message.

[0091] In the following, an example of a subsequent RRC connection release procedure for a UE to transition from RRC_Connected to RRC Inactive state (see section 5.3.8 of 3GPP TS 21.2006) is described with reference to FIG. 11. The purpose of this procedure is to release the RRC connection or to suspend the RRC connection. For example, the network initiates the RRC connection release procedure to transition a UE in RRC_CONNECTED to RRC_IDLE or RRC_INACTIVE. The actions taken by the UE in the RRC connection release procedure (see section 5.3.8.3 of 3GPP TS 21.2006) include suspending all SRBs (Signaling Radio Bearers) and DRBs (Data Radio Bearers) except SRB0, if the release is due to suspension (e.g. RRCRelease includes suspendConfig). Thus, a UE in RRC Inactive state has no unsuspended or active DRBs (the UE only has suspended DRBs). SRB0 is kept active even in the RRC Inactive state and may be used by the UE to perform the RACH procedure when carrying RRC messages such as, for example, RRCResumeRequest, RRCResumeRequest1, RRCSetupRequest, etc.

[0092] The term "inactive state" as used in this application shall be understood broadly as a state in which normal extensive data exchange between the UE and the base station is not possible or is not common. For example, when the UE is in an inactive state (e.g., referred to as an "inactive UE"), it may not have an actively-used data connection, but it may still have one or more inactive data connections (e.g., one may say that they exist but are not currently used) that allow the transmission of (small) data without the need to first resume the data connection. It should be noted that a UE in an "idle state" does not have a data connection through which the UE can transmit data to the base station, while a UE in a "connected state" has one or more active data connections that can be immediately used to convey data to the base station.

[0093] <Small data transmission> The small data transmission characteristic of interest in this disclosure refers to any service characterized by small data bursts in UL / DL, optionally fairly infrequent, and no strict requirements on delay. For example, a single data transmission that is small enough that a UE can transmit in a single transmission (e.g., in a RACH or one CG occasion, see below) can be considered as a small data transmission. The following table summarizes typical, non-limiting examples of traffic characteristics of small data transmission (see Section 5 of Non-Patent Document 9):

[0094] [Table 2]

[0095] Other different possible exemplary definitions may depend on the configuration of the gNB. For example, the gNB may define that data below a certain threshold (e.g., 1000K bytes) is considered small data, while data above that threshold is not considered small data. This threshold may be defined, for example, in relation to the state of the UE's buffer.

[0096] Alternatively, the definition of what small data is can also be fixed by an appropriate 3GPP standard, for example, by defining a data volume threshold similar to the above.

[0097] <Data Transmission by UE in RRC INACTIVE State - SDT Procedure> More specifically, in 5G NR, the RRC_INACTIVE state is supported, and UEs with (periodic and / or aperiodic) low-frequency data transmission are generally maintained in the RRC_INACTIVE state by the network. Until Release 16, data transmission is not supported in the RRC_INACTIVE state. In Non-Patent Document 10 (see Section 5.x), small data transmission in the inactive state is being considered. Therefore, the UE needs to resume the connection (e.g., transition to the RRC_CONNECTED state) for DL (Mobile Terminated) and UL (Mobile Originated) data. Even if the data packet is very small and the frequency is low, the establishment (or resumption) of the connection and subsequent release to the RRC_INACTIVE state occur for each data transmission. As a result, unnecessary power consumption and signaling overhead are generated.

[0098] Specific examples of small and low-frequency data traffic include the following use cases. - Smart phone applications: 〇 Traffic from instant messaging services (such as whatsapp, QQ, wechat, etc.) 〇 Heartbeat / keep-alive traffic from IM / mail clients and other applications 〇 Push notifications from various applications - Applications other than smart phones: 〇 Traffic from wearable devices (such as periodic location information, etc.) Sensors (e.g. industrial wireless sensor networks transmitting temperature and pressure measurements periodically or in an event-triggered manner) Smart meters and smart meter networks that periodically transmit meter readings Small data transmissions may support a variety of packet sizes and may have a variety of traffic requirements.

[0099] For example, for heartbeat traffic / keep alive traffic, the packet size is around 50 bytes to 100 bytes. Moreover, heartbeat messages arrive every 5 minutes or every second. For smart meters, which send meter readings periodically, the packet size is around 12 to 100 bytes for normal transmission. For sensors sending periodic traffic or event-triggered traffic (non-periodic traffic), the packet size is around 8 bytes to 128 bytes. For instant messages (traffic pattern is not deterministic), which can deliver text, photos, videos, etc., the packet size can vary from 100 bytes to 1000 bytes. For push notifications, the traffic pattern is In the following, an exemplary procedure of the prior art (in this case a prior art solution compliant with 5G NR) for enabling a UE in an RRC Inactive state to transmit (small) data after transitioning to an RRC Connected state is briefly described with reference to FIG. 12. As is clear from the figure, the UE is assumed to be in an RRC_Inactive state, where, for example, the UE (and the gNB) have suspended all data radio bearers and cannot transmit data to the gNB. To enable the UE to transmit data, the UE must first transition to an RRC Connected state, which can be done by the UE requesting resumption of the RRC connection (here sending an RRCResumeRequest) as part of a RACH procedure (in FIG. 12, for example, using a 4-step RACH procedure).

[0100] In detail, the UE sends a preamble to the current gNB and receives a corresponding random access response containing a small UL grant of radio resources, using which the UE can send a RRCResumeRequest message as msg3 of the RACH procedure.

[0101] Finally, the new gNB provides an RRCResume message to the UE and the UE transitions to the RRC Connected state, including the resumption of all data radio bearers. In the RRC_Connected state, the UE can transmit UL data.

[0102] It remains to be defined when and how the gNB decides that the UE should transition to the RRC_CONNECTED state after such a UL small data transmission. It is possible that the UE may request the resumption of the RRC connection, but the control in this respect is likely still left to the gNB. As one exemplary possibility, the gNB decides whether the UE should transition to the RRC_CONNECTED state or not considering a buffer status report that the UE may send, for example, in Msg3 or MsgA. The buffer status report indicates the actual amount of data in the UE's buffer. For example, if the buffer status report indicates that there is a large amount of data in the UE's buffer, the gNB may decide to transition the UE from the RRC_INACTIVE state to the RRC_CONNECTED state (e.g., by the gNB sending a RRCResume message). On the other hand, if the buffer status report indicates that there is only a little data in the UE's buffer, the gNB may decide to keep the UE in the RRC_INACTIVE state (e.g., by the gNB sending a RRCRelease message). Furthermore, the absence of a buffer status report in Msg3 / MsgA can also provide an indication to the gNB that, for example, no further data is available in the UE buffer and the UE can remain in RRC_INACTIVE.

[0103] As can be seen from the illustration in Fig. 12, according to the above process, the UE needs to first transition from an INACTIVE state to a CONNECTED state so that it can transmit user data in the uplink, thus introducing latency and consuming significant UE power for each transmission of user data. Furthermore, the signaling overhead incurred in an INACTIVE UE when transmitting small data packets is a common problem that will be exacerbated with the increasing number of UEs in 5G NR.

[0104] Therefore, 3GPP intends to allow RRC_Inactive UEs to transmit small data in the uplink without changing their state to RRC Connected. In general, devices that experience intermittent small data packets while in the INACTIVE state would benefit from allowing transmission of small data in the INACTIVE state.

[0105] The following assumptions made with respect to Figures 13 and 14 and with respect to the subsequent description of the concepts, solutions and variants of the present invention are merely illustrative and should not be considered as limiting the uplink transmission of RACH-based small data in accordance with the present invention.

[0106] Furthermore, assuming uplink transmission of small data based on RACH as an example, the UE can transmit small data in the uplink using either a two-step RACH or a four-step RACH (see MsgA or Msg3). A simplified exemplary RACH-based small data uplink transmission procedure is shown in Figure 13 and Figure 14. In both Figure 13 and Figure 14, it is assumed for the sake of example that the UE is already in RRC_INACTIVE state and has small data available for transmission. Figure 13 assumes a four-step RACH procedure and shows how the UE transmits small data with Msg3. Figure 14 assumes a two-step RACH procedure and shows how the UE transmits small data by MsgA.

[0107] According to an example, the control message and the small data are transmitted together, for example in the same transport block, to the base station. In this case, the UE uses resources to build the transport block and multiplexes data and signaling together in the same transport block of the MAC layer. In the case of a four-step RACH, the small data is transmitted in Msg3, for example based on the radio resources granted through the uplink grant received from the gNB in ​​Msg2. In the case of a two-step RACH, the small data is transmitted in MsgA, for example using radio resources selected by the UE from among the previously configured radio resources in association with the selected RACH preamble.

[0108] Further, while Figures 13 and 14 show that a buffer status report can be included in Msg3 and MsgA, respectively, the BSR is only shown in brackets to show that including the BSR is merely an exemplary possibility. For example, in Figure 13, it is assumed exemplarily that the gNB decides to keep the UE in RRC_Inactive state, for example because the BSR is not present or indicates only a small amount of uplink small data in the UE buffer. Thus, in Msg4, the RRCRelease message is sent. Meanwhile, in Figure 14, it is assumed exemplarily that the gNB decides to transition the UE to RRC_Connected state, for example because the BSR indicates a large amount of uplink data in the UE buffer that must be transmitted by the UE. Thus, in MsgA, the RRCResume message is sent.

[0109] Furthermore, although in FIG. 13 the uplink grant is shown separately from the Random Access Response of Msg2, in FIG. 13 and similar implementations below, the uplink grant may equally be considered to belong to and be part of the Random Access Response.

[0110] In summary, an exemplary implementation of small data uplink transmission by a UE in RRC_INACTIVE state is possible and can be based, for example, on a RACH procedure (two-step or four-step RACH procedure) (see Figures 13 and 14).

[0111] Above we mentioned a single small data uplink transmission (e.g. using Msg3 / MsgA of the RACH), and 3GPP agreed that a UE in RRC_INACTIVE state should be able to send (and receive) multiple UL (and possibly DL) transmissions using the same procedure without transitioning to RRC_CONNECTED state.

[0112] For example, the UE may be informed by the network node about Downlink SDT (DL-SDT), i.e. Mobile Terminated SDT (MT-SDT), if one or more of the following conditions are met: - All pending data in the network node is mapped to a Radio Bearer (RB) configured for SDT. - If the amount of pending DL data through all RBs configured for SDT is below the data amount threshold of the network node - If the DL Reference Signal Received Power (RSRP) is less than the RSRP threshold for the SDT procedure - If the UE supports SDT

[0113] Therefore, the SDT procedure or the procedure of transmitting SDT DRB data refers to the procedure of transmitting data in an inactive state (e.g., RRC_INACTIVE), and does not necessarily refer to the amount of data transmitted by the SDT procedure. Therefore, small data and SDT DRB data refer to data that can be transmitted in an inactive state (Inactive state) of the UE, and does not necessarily refer to the size of the data. In particular, small data or SDT DRB data may be any data of a DRB configured for transmission in an inactive state (such a DRB is also referred to as an SDT DRB). Similarly, non-SDT DRB data refers to data that cannot be transmitted in an inactive state (of the UE) and / or data that can be transmitted only in a connected state (of the UE). In particular, non-SDT DRB data may be any data of a DRB that is not configured for transmission in an inactive state (such a DRB is also referred to here as a non-SDT DRB).

[0114] The procedure for transmitting SDT DRB data may be based on the RACH procedure and / or initiated by the RACH procedure. In particular, the RACH procedure may be a four-stage RACH or a two-stage RACH. More specifically, the SDT procedure based on the RACH procedure here refers to an SDT procedure initiated in the RACH procedure. This includes not only an SDT procedure in which only one small data transmission is performed during the RACH procedure, as shown in Figures 13 and 14, but also an SDT procedure in which one or more small data transmissions are performed during and / or after the RACH procedure. It should be noted that this also includes SDT procedures that are terminated together with the RACH procedure that they initiated.

[0115] In summary, the SDT procedure may be a procedure based on or initiated by a RACH procedure, in which one or more data transmissions are performed in an inactive state, and (i) at least one of the one or more transmissions is performed by the UE together with a message of the RACH procedure, and / or (ii) together with the one or more transmissions, a notification indicating a request for a resource grant for the transmission of small data is sent by the UE together with a message of the RACH procedure.

[0116] However, the term SDT procedure is not limited to the RACH-based SDT procedure, but also includes data transmission in an inactive state using a Configured Grant (CG).

[0117] Furthermore, multiple devices (UEs) may be able to share a periodic radio resource called configured grant (CG), which facilitates reducing waste of periodic radio resources compared to SPS in LTE. Alternatively, the gNB may define the periodic radio resource such that it is not shared or is not fully shared among multiple UEs. The gNB assigns the configured grant radio resource to one or more UEs, which then randomly utilize the periodic radio resource when they need to transmit data (e.g. small data) (see later section). With CG, the network eliminates packet transmission delays caused by a specific scheduling request procedure that would otherwise have to be performed before data can be transmitted. This may also increase the utilization of the allocated periodic radio resource.

[0118] 3GPP Release 16 supports two types of grant-free configuration methods, namely, Type 1 and Type 2 (see Non-Patent Document 1, "NR; NR and NG-RAN Overall Description; Stage 2 (Release 16)", Version 16.6.0, Section 10.3).

[0119] According to this exemplary implementation of Non-Patent Document 1, the RRC uses Type 1 CG to provide a configure uplink grant, including for example a periodicity, directly to one or more UEs.

[0120] In type 2 configured grant, RRC defines the periodicity of the configure uplink grant, but a PDCCH message addressed to the CS-RNTI of one or more UEs can signal the configure uplink grant to activate or deactivate it, and the PDCCH addressed to the CS-RNTI indicates that the uplink grant can be implicitly reused according to the periodicity defined by RRC until it is deactivated. In other words, additional L1 signaling (e.g., PDCCH) is introduced, and the uplink is semi-persistently scheduled by an RRC-based uplink grant that is activated / deactivated by the (de)activation DCI. RRC provides higher layer parameters for CG configuration.

[0121] In both cases, according to an exemplary 3GPP implementation, the RRC provides the grant configuration to the UE through a higher layer parameter called ConfiguredGrantConfig (see 3GPP TS 2.3.1, v16.5.0, section 6.3.2 "Radio resource control information elements").

[0122] The resource configuration of the CG may include physical resources in the time and / or frequency domain and / or reference signal (RS) parameters, which may further include a modulation and coding scheme (MCS), a repetition number, a repetition period, and / or a transport block size.

[0123] More specifically, the UE may initiate a CG-based SDT procedure by sending a corresponding notification to the scheduling device using the configured CG resource. The UE may start transmitting SDT DRB data using the CG resource simultaneously with or after sending the notification. For example, upon arrival of the SDT DRB data, the UE may multiplex the SDT DRB data with the RRCResumeRequest message and transmit it on the nearest CG resource. The CG resource is a UL grant that appears at a regular period by the scheduling device before / when the UE enters an inactive state.

[0124] <Data connection> A data connection in this context may refer to, for example, a connection that allows data (e.g., small data) to be transmitted and received between the UE and the radio base station. More specifically, a UE without a data connection cannot immediately transmit data even if it is connected to the radio base station based on, for example, a signaling connection. Data in this context may broadly include, for example, user data from applications running on the UE, as opposed to control information that is often transmitted using a signaling connection.

[0125] In one embodiment, in accordance with the 5G NR standard, the data connection can be understood as a DRB (Data Radio Bearer) and the signaling connection can be understood as a SRB (Signaling Radio Bearer).

[0126] In this application, a distinction is also made between various states of a data connection, such as not existing, existing but suspended, existing but not being used (non-suspended, also referred to as inactive), and existing but being used for transmitting data (active). According to this classification of data connections, a suspended data connection exists but has been suspended by both endpoints (e.g., the UE and the radio base station) and is not immediately usable for transmitting data (e.g., uplink) and must be resumed first. On the other hand, a non-suspended data connection may allow immediate data transmission (e.g., without going through a procedure such as resuming a data connection). For example, with reference to an example implementation of 5G NR currently defined in the 3GPP standard, a UE in an RRC Inactive state has one or more suspended data connections (DRB is suspended), a UE in an RRC Connected state has one or more active data connections and possibly other non-suspended (not currently actively used) data connections, and a UE in an RRC Idle state has no data connections (neither suspended nor active). However, as described below, for a UE in RRC Inactive state, according to improved data transmission procedures not present in the 5G NR implementation in the current 3GPP standard, one or more non-interrupted data connections are available (these are inactive since no data transmission is taking place until the small data transmission).

[0127] In this context, it is described herein that a data connection is used, for example, by a UE to transmit and receive small data. In this scenario, a data connection is established between the UE and a base station. In one embodiment, it is understood that a data connection is broadly defined as relating to certain parameters related to coding, security, encryption, etc. Thus, from the perspective of the transmitting side, the UE applies these parameters associated with the data connection to the (small) data it transmits using this data connection. This may be done, for example, to ensure a certain Quality of Service (QoS). Accordingly, from the perspective of the receiving side, in order to successfully decode the data transmitted over the data connection, it may be necessary to perform the reverse processing (e.g., processing related to coding, security, encryption, etc.) at the receiving side as at the transmitting side.

[0128] <Terminology> In the following, UEs, base stations, and procedures are described for new radio access technologies envisioned in 5G mobile communication systems (but which can also be used in LTE mobile communication systems). A number of different implementations and variations are also described. The following disclosure is facilitated by, and may be based, for example, at least in part on, the discussion and findings above.

[0129] In general, it should be noted that many assumptions have been made herein to allow the principles underlying the present disclosure to be explained in a clear and easily understandable manner, but it should be understood that these assumptions are merely examples made herein for the purpose of explanation and are not intended to limit the scope of the present disclosure.

[0130] Furthermore, although the specific terminology used in the context of new radio access technologies for the upcoming 3GPP 5G communication system has not yet been fully determined or may eventually change, some of the terms such as procedures, entities, layers, etc. used below are closely related to the terms used in the LTE / LTE-A system or in the current 3GPP 5G standardization. Thus, the terms may change in the future, but without affecting the functionality of the embodiments. Therefore, it will be appreciated by those skilled in the art that the embodiments and their scope of protection are not limited to the specific terms used illustratively herein due to the absence of newer or finally agreed upon terms, but should be understood more broadly in terms of the functions and concepts underlying the functions and principles of the present disclosure.

[0131] <Embodiment Mode> In general, as already indicated, it may be desirable to allow an inactive UE to receive multiple DL transmissions without transitioning to a connected state.

[0132] In light of this, the present disclosure provides techniques to facilitate efficient initiation of DL transmission of small data. In particular, the disclosed procedures can inform a UE about mobile terminated (i.e., downlink) small data transmission (MT-SDT) using paging messages and / or notifications for small data. Enabling MT-SDT in an inactive state can help UE power savings and reduce signaling overhead.

[0133] The present disclosure provides network nodes and user equipment, as well as corresponding methods and programs. For example, the integrated circuit may control the processing of the UE or the network node. As shown in FIG. 16, the user equipment 1710 and the network node 1760 may communicate over a radio channel 1750 in a wireless communication system. For example, the user equipment may be an NR user equipment, and the network node may be a base station or a scheduling node, such as an eNB, or an NR gNB, in particular a gNB in ​​a Non-Terrestrial Network (NTN) NR system. An example of such a communication system is shown in FIG. 16. The communication system 1700 may be a wireless communication system conforming to 5G technical specifications, in particular an NR communication system. However, the present disclosure is not limited to 3GPP NR, and may also be applied to other wireless systems such as NTN or cellular systems. FIG. 16 shows a general schematic exemplary block diagram of the user equipment 1710 (also referred to as a communication device) and the network node 1760. However, in general, the scheduling device may be a terminal in case of a sidelink connection between two terminals. Also, particularly with respect to URLLC, eMBB, and mMTC applications, the user equipment 1710 may be a sensor device, a wearable device, or a connected car, or a controller of automated equipment in an industrial factory, and may be capable of acting as an intermediary between the network node 1760 and other communication devices (e.g., but not limited to, a communication "terminal" or a user "terminal").

[0134] The UE and the eNB / gNB communicate with each other using respective transceivers 1720 (UE side) and 1770 (network node side) via a (radio) physical channel 1750. The network node 1760 and the terminal 1710 constitute a communication system 1700. The communication system 1700 may further include other entities as shown in FIG.

[0135] As shown in FIG. 16 (left side), a user equipment (UE) 1710 according to a first embodiment is provided. The UE 1710 includes a transceiver 1720 and a circuit 1730. In operation, the circuit 1730 receives a paging message when the UE is in an inactive state. In response to the paging message, the UE remains in an inactive state for small data reception. While the UE is in an inactive state, a response to the paging message is transmitted to a network node within a transmission opportunity associated with a preconfigured resource. Such paging while remaining in an inactive mode is illustrated in FIG. 15 as an example.

[0136] In general, the circuitry 1730 may control the transceiver 1720 to receive and / or transmit data. This is indicated by arrow 1725, which generally represents an interface between the circuitry 1730 and the transceiver 1720 through which control takes place. For example, the circuitry 1730 may signal 1725 the transceiver 1720 to transmit such a response to such a paging message. Similarly, the circuitry 1730 may control the transceiver 1720 to receive paging messages and may receive paging messages from the transceiver 1720 via such interface 1725.

[0137] 17 shows a functional structure of an example of the circuit 1730, particularly the circuit 1735 for handling small data. As an example, the SDT handling circuit 1735 may include a paging message detection circuit 1736 and a response transmission circuit 1737. More specifically, the circuit 1736 detects a paging message by monitoring a pre-configured paging resource. The circuit 1736 may also determine whether small data is expected to arrive. The response transmission circuit 1737 may determine whether to respond to a received paging message.

[0138] In association with the UE, a communication method according to a first embodiment is a communication method performed by a UE in an inactive state. As shown in FIG. 19, the method includes the following steps: - receiving a paging message (S1910); - remaining in an inactive state for receiving small data in response to a paging message (S1920); - remaining in an inactive state and transmitting a response to the paging message to the network node within a transmission opportunity associated with a preconfigured resource (S1930); The process includes the steps of:

[0139] As also shown in Fig. 16 (right side), according to the first embodiment, a network node 1760 is provided. The network node 1760 includes a transceiver 1770 and a circuit 1780. The circuit 1780 operates to transmit a paging message to an inactive UE and to receive a response from the inactive UE indicating that the inactive UE is ready to receive small data.

[0140] In general, the circuitry 1780 may control the transceiver 1770 to receive and / or transmit data. This is indicated by arrow 1775, which is a schematic representation of an interface between the circuitry 1780 and the transceiver 1770 through which control takes place. For example, the circuitry 1780 may instruct 1775 the transceiver 1770 to transmit a paging message as described above. Similarly, the circuitry 1780 may control the transceiver 1770 to receive responses to said paging messages, which responses may be received from the transceiver 1770 via said interface 1775.

[0141] 18 illustrates a functional structure of one embodiment of the SDT handling circuit 1785. In particular, the SDT handling circuit 1785 may include a paging message transmission circuit 1836 and a UE response detection circuit 1837. The circuit 1836 may be responsible for sending paging messages and / or SDT notifications, and the circuit 1837 may be responsible for receiving responses from the UE in an inactive state.

[0142] Further, there is provided a communication method performed by a network node associated with the above base station. As shown in FIG. - sending a paging message to the UE in an inactive state (S2010); and - receiving a response from the UE in the inactive state (S2020), the response indicating that the UE is ready to receive the small data in the inactive state.

[0143] The UL response may provide feedback to the network node that the UE has started SDT, which may include, for example, starting a timer (e.g., starting and running an SDT timer) so that the UE expects DL-SDT data (e.g., including monitoring a control channel associated with the downlink shared data channel).

[0144] The UE 1710 may include a transceiver 1720 and a (processing) circuit 1730, and the network node 1760 may include a transceiver 1770 and a (processing) circuit 1780. The transceiver 1710 may include or function as a receiver and / or a transmitter. In this disclosure, the term "transceiver" is used for hardware and software components that enable the communication device 1710 or the base station 1760 to transmit and / or receive wireless signals over the wireless channel 1750. Thus, a transceiver corresponds to a receiver, a transmitter, or a combination of a receiver and a transmitter. Typically, it is assumed that base stations and communication devices can transmit and receive wireless signals. However, for some applications (smart home, smart city, industrial automation, etc.), especially for eMBB, mMTC, and URLLC, devices such as sensors may only transmit signals. The term "circuit" also includes a processing circuit formed by one or more processors or processing units, etc. The circuits 1730 and 1780 (or processing circuits) may be hardware such as one or more processors, or hardware such as any LSI. An input / output point (or node) exists between the transceiver and the processing circuit, and the processing circuit, in operation, can control the transceiver through this input / output point (or node), i.e., control the receiver and / or the transmitter, and exchange receive data / transmit data.

[0145] The transceiver as a transmitter and a receiver may include an RF (radio frequency) front including one or more antennas, amplifiers, RF modulators / demodulators, etc. The processing circuit may perform control tasks such as controlling the transceiver to transmit user data and control data provided by the processing circuit and / or receive user data and control data to be further processed by the processing circuit. The processing circuit may also be responsible for performing other processes such as judgments, decisions, calculations, measurements, etc. The transmitter may be responsible for performing the process of transmission and other processes related to transmission. The receiver may be responsible for performing the process of reception and other processes related to reception (such as monitoring the channel).

[0146] Additionally, any of the steps / operations / methods described below may be performed or controlled by circuitry 1730 (UE side) and / or circuitry 1780 (network node side).

[0147] In the following description, unless otherwise stated explicitly or by context, the details and embodiments of each of the user equipment, network node, and method apply to each of them. Note that each step described below may be included as code instructions in a program or may be executed by one or more processors (e.g., circuit 1730 and / or circuit 1780).

[0148] <MT-SDTのためのページング> Assume that at some point while the UE 1710 is in an inactive state, small data becomes available for transmission from the network node 1760 to the UE 1710.

[0149] When the UE 1710 is in an inactive state, it receives a paging message from the network node 1760 when small data for downlink transmission arrives (S1910). Paging may be via CN paging, RAN paging, etc.: for example, the UE monitors a paging channel for CN paging with 5G-S-TMSI or RAN paging with full I-RNTI. For more details, see RRC states.

[0150] In the 5G NR standard, the inactive state corresponds to, for example, an RRC_INACTIVE state. The paging message may be a paging message defined by current and / or future standards. For example, the paging message may be interpreted by a non-SDT-capable UE as a notification of returning to a connected state, for example, an RRC_CONNECTED state.

[0151] In response to receiving such a paging message, the SDT-enabled UE 1710 according to the present disclosure remains in an inactive state for receiving small data (S1920). In particular, the SDT-enabled UE 1710 may determine to remain in an inactive state according to a definition of the standard, a (default) configuration of the UE, etc. For example, the standard may specify that the UE always remains in an inactive state upon receiving a paging message. In response, the UE determines to remain in an inactive state. In another example, the standard may specify configurability of the UE's behavior when the UE receives a paging message. Such configurability may include, for example, a default configuration of remaining in an inactive state. The UE may determine its configuration based on the paging message (e.g., whether it arrived via PDCCH or PDSCH, etc.) or by receiving a configuration from a network node, etc.

[0152] In other words, by receiving such a paging message, the inactive UE 1710 detects the possibility of small data arrival. The SDT-enabled UE 1710 can interpret such a (standard) paging message as a notification of the possibility of receiving small data.

[0153] The SDT-enabled UE 1710 of the present disclosure may not interpret such paging as a notification to return to a connected state. Here, "arrival" refers to arrival from a higher layer. In other words, the above small data can be transmitted. Note that "detection" includes not only detection of actual data arrival, but also detection / determination that small data arrival is expected.

[0154] The UE 1710 responds to the paging message by transmitting a response to the network node 1760 (S1930) while remaining in an inactive state. The response is transmitted within a transmission opportunity associated with preconfigured resources. The preconfigured resources include, for example, resources used for the transmission of the RACH procedure and resources assigned to the UE by a Configured Grant (CG) procedure. The transmission opportunity results from the definition and implementation of the above procedures. The RACH procedure, as well as the CG procedure, have been described in detail in the section on data transmission in the RRC Inactive state of the UE above. However, the present disclosure is not limited to the RACH procedure or the CG procedure, and may be any current or future procedure for transmitting a UL response in an inactive state.

[0155] Thus, the response to the paging message may include at least one of RA-SDT (Random Access Small Data Transmission), CG-SDT (Configured Grant Small Data Transmission) and MT-SDT (Mobile Terminated Small Data Transmission). The decision to use RA-SDT or CG-SDT for the UL response may be made according to the UL-SDT described in "Data Transmission by UE in RRC Inactive State". MT-SDT shows an example of a procedure envisioned for a future 3GPP 5G NR release. MT-SDT may cover not only UL transmission (similar to the current RA-SDT, CG-SDT) but also DL transmission for UE in inactive state. MT-SDT may include elements of RA-SDT and / or CG-SDT, or may be a mixture of both RA-SDT and CG-SDT. MT-SDT may be a new UL and / or DL ​​transmission designed specifically for UE operating in inactive state.

[0156] When responding to the paging message, the UE 1710 may remain in an inactive state and receive small data from the network node 1760. For example, the small data may be a message including a payload. A specific example of small data including a payload has already been described in "Small Data Transmission". For example, the small data may include an indication that the UE 1710 is in a connected state. In other words, the network node may transmit a resume message (e.g., RRC_RESUME) to the SDT-capable UE using the MT-SDT procedure.

[0157] In other words, if the DL data is normal (SDT non-compatible) data, the network node (eNB / gNB) may respond with RRC_Resume when receiving a UL response from the UE, and notify the SDT compatible UE 1710 of a transition to RRC_CONNECTED mode.

[0158] As already shown, whether to remain in the inactive state is determined according to UE settings. Such settings may be pre-stored settings, settings received from a network node, or default settings of the UE or the like.

[0159] <UE settings> The (default) UE settings of UE1710 include settings regarding the default behavior when receiving paging messages. This "UE setting" describes the current settings of the UE. Note that the UE setting may be, for example, default initial settings set by a standard and / or a network according to UE capabilities, or by the UE itself. Note that the UE setting may be set (adopted) or reset, for example, based on the received (e.g., via RRC) settings. Hereinafter, exemplary embodiments of such UE setting setting and / or receiving and / or transmitting (information) will be described. These embodiments can be performed alone or in combination.

[0160] 1. According to UE capabilities According to the above UE configuration, SDT initialization can be performed by default upon paging. For example, such UE configuration is configured in the UE 1710 depending on the capabilities of the UE 1710. In this case, the UE 1710 determines its own capabilities and performs configuration according to the capabilities. The UE 1710 indicates its capabilities to the network node 1760 while in a connected state. For example, such UE capabilities may include the nature and / or requirements of the UE. For example, the SDT capabilities of the UE may be defined based on the type of SDT. Such SDT types include, for example, RA-SDT, CG-SDT, new SDT types for DL ​​(e.g., MT-SDT), etc. For example, depending on the UE category that supports SDT and / or for which SDT is configured, a UE in an inactive state may start SDT by default upon paging. Such a UE category may define the combined uplink and downlink capabilities of the UE as specified by current or future standards.

[0161] For example, a UE reports its capabilities via a UECapabilityInformation message, which is an RRC message that the UE 1710 sends to the network node 1760 (e.g., during an initial registration process or upon request from the network node). The UECapabilityInformation message contains detailed information about the capabilities of the UE.

[0162] For example, the network node 1760 may request capability information, including transmission capability information, from the UE 1710 by sending a UECapabilityEnquiry message to the UE 1710. The UECapabilityEnquiry is an RRC message sent by the network node 1760 to request detailed information about the capabilities of the UE. The UE 1710 receives the inquiry and reports its capabilities via a UECapabilityInformation message.

[0163] In other words, an SDT-capable UE 1710 is configured to remain in an inactive state and respond to the network node as described above if it receives a paging message. An SDT-capable UE reports its configuration to the network while in a connected state. A network node may request to receive information about UE capabilities from a UE in a connected state.

[0164] 2. Depending on semi-static information received by the UE The network node 1760 may transmit a configuration for MT-SDT to the UE 1710 in a connected state. Such transmitted configuration may include, for example, a standard-specific configuration, a network node configuration, a network configuration, etc., or a combination thereof. The UE 1710 may receive the configuration, for example, before transitioning from a connected state to an inactive state. The UE 1710 performs (adopts) a UE configuration accordingly. The configuration may be received from the network node 1760. In general, the configuration may be received from the network node at any time, for example, during the period during which the UE 1710 is in a connected state.

[0165] However, the present disclosure is not limited thereto, and even if the UE is in an inactive mode, it may receive such a setting at some point in the small data, for example.

[0166] It should be noted that the network node may transmit the configuration semi-statically, especially in the context of NR. "Semi-static" in NR refers to higher layer signaling, especially RRC. Such signaling is less dynamic than that used for shared channel control signaling, which is used to indicate resource allocation (e.g. on PDCCH), but may be received even after connection setup, typically during the connection (e.g. connected mode).

[0167] For example, when the UE 1710 is informed of the transition to RRC_INACTIVE, semi-static information about the (default) UE configuration is given to the UE 1710 by the network node 1760. When the UE 1710 in RRC_CONNECTED transitions to RRC_INACTIVE by receiving an RRCRelease with a suspend message, the same message includes the semi-static information (e.g. the information element SDT-Config).

[0168] The SDT-Config may contain default settings (e.g., "sdt-Paging" field) regarding the default behavior / state of the UE that triggers MT-SDT by paging (as exemplified below). The SDT-Config may be included in the SuspendConfig field included in the RRC release (with suspend). Such a SuspendConfig is also illustrated below.

[0169] [Table 3]

[0170] As an example, SDT-Config contains a field sdt-Paging. If sdt-Paging is set to "true", UEs receiving the configuration are informed to adopt the configuration and start the SDT by paging. As an example, SuspendConfig contains a field sdt-Config that may be set to contain the value sdt-Config.

[0171] It should be noted that the illustrated example of the ASN.1 signaling field is not limited to the ENUMERATED type, but may be of other types such as BOOLEAN.

[0172] After transitioning to RRC_INACTIVE, the UE 1710 is configured to initiate an SDT by paging and transmit a response, as described above.

[0173] 3. According to UE's preference The UE 1710 may also report the preferred UE configuration to the network node 1760. To this end, the UE 1710 may transmit information regarding the preferred UE configuration to the network node 1760 while in a connected state. For example, the UE 1710 may include the notification in a UEAssistanceInformation message. An example of such a message is shown below.

[0174] [Table 4]

[0175] Such an exemplary SDTPreference includes a preferred state for receiving small data (eg, connected or inactive).

[0176] Such a message indicates a preference for the UE 1710 to initiate an SDT for paging or not, such preference may be indicated by standard, UE capability, UE type, etc.

[0177] Upon receiving the message, the network node 1760 may inform the UE 1710 of the decision regarding the default state (SDT or non-SDT upon paging) before the UE 1710 transitions to the inactive state. Such notification may be as detailed above for configuration depending on semi-static information received by the UE. The network node's decision may include a decision depending on the standard, a network node configuration, a network configuration, etc., or a combination thereof.

[0178] The UE 1710 may respond to a paging with information regarding its SDT preferences, either network initiated (e.g., via an RRC Reconfiguration procedure) or UE initiated (e.g., paging).

[0179] 4. Depending on the radio bearer settings The UE configuration may be configured or reconfigured based on the configuration of the radio bearers, for example, if all of the data radio bearers (DRBs) and / or at least one of the signaling radio bearers (SRBs) are configured for SDT, the UE configuration may include a default behavior of the UE to initiate SDT by responding to paging.

[0180] The multiple SRBs may include SRB0, SRB1, and SRB2. For example, one or more of SRB1 and SRB2 may be configured for SDT purposes. And, the UE 1710 may be configured or reconfigured to initiate SDT in response to paging.

[0181] The configuration of the UE in an inactive state may include configuration of a plurality of DRBs, including one or more DRBs, and if all DRBs of the plurality are configured for SDT, the UE 1710 may be configured or reconfigured to initiate SDT by default.

[0182] 5. In response to SI change notice The UE 1710 can receive the System Information (SI) change notification (together with all UEs in the same cell). UEs in inactive state can receive the SI change notification via paging by short message sent with P-RNTI on DCI.

[0183] The UE 1710 executes the SI acquisition procedure received by the SIB (System Information Block) and updates the SDT configuration. Such an SI acquisition procedure may be initiated by a network node or may be initiated by the UE. For example, the SI may be periodically broadcast by the network node to all UEs in the cell. For example, the UE may request the transmission of the SI.

[0184] For example, the SDT default settings may be included in SIB1 as follows:

[0185] [Table 5]

[0186] As an example, the SDT-ConfigCommonSIB includes a field called sdt-Paging. If sdt-Paging is set to "true", the UE that receives the configuration is notified to adopt the configuration and start the SDT by paging.

[0187] Such settings are common to all UEs in a cell.

[0188] According to the received SI change notification, the UE 1710 configures or reconfigures the UE settings.

[0189] Thus, by default, the UE 1710 will initiate an SDT in response to the paging and will send a UL response to the network node 1760 as described above.

[0190] <Notification for MT-SDT in paging message or short message> In a second exemplary embodiment for implementing paging for downlink small data transmission, a notification is sent to the UE, whereby the UE receives a notification to receive the small data from the network node.

[0191] Note that the exemplary UE shown in FIG. 16 (left side) described above may be configured to perform MT-SDT according to the second exemplary embodiment.

[0192] The UE 1710 of FIG. 16 includes a transceiver 1720 and a circuit 1730. In operation, the circuit 1730 receives a notification to receive small data from a network node. When the UE 1710 receives the notification, the UE 1710 remains in an inactive state for receiving the small data. The UE remains in an inactive state and transmits a response to the notification to the network node.

[0193] In general, the circuitry 1730 may control the transceiver 1720 to receive and / or transmit data. This is indicated by arrow 1725, which is a schematic representation of an interface between the circuitry 1730 and the transceiver 1720 through which control takes place. For example, the circuitry 1730 may instruct 1725 the transceiver 1720 to transmit said response to the SDT notification. Similarly, the circuitry 1730 may control the transceiver 1720 to receive said paging messages and to receive said notifications from the transceiver 1720 via said interface 1725.

[0194] In association with the UE, according to a second embodiment, a communication method performed by a UE in an inactive state is provided. As shown in FIG. 21, the method includes the steps of: - receiving a notification to receive small data from a network node (S2110); - remaining in an inactive state for receiving small data in response to the paging message (S2120); - transmitting a response to the paging message to a network node while remaining in the inactive state (S2130).

[0195] Such a method for implementing MT-SDT according to the second exemplary embodiment may be implemented separately in the UE, or may be implemented in addition to the method according to the first exemplary embodiment.

[0196] As illustrated in Fig. 16 (right side), a network node 1760 according to a second exemplary embodiment is provided. The network node 1760 includes a transceiver 1770 and a circuit 1780. In operation, the circuit 1780 transmits a notification to a UE in an inactive state to receive small data. The network node receives a response from the UE in an inactive state indicating that the UE is ready to receive the small data in the inactive state.

[0197] In general, the circuit 1780 may control the transceiver 1770 to receive and / or transmit data. This is indicated by arrow 1775, which is a schematic representation of an interface between the controlled circuit 1780 and the transceiver 1770. For example, the circuit 1780 may instruct 1775 the transceiver 1770 to transmit the notification. Similarly, the circuit 1780 may control the transceiver 1770 to receive a response to the notification, which is received from the transceiver via said interface 1775.

[0198] Further, there is provided a communication method performed by a network node according to a second exemplary embodiment in association with the above base station. As shown in FIG. 22, the method includes the steps of: - sending a notification to an inactive UE to receive small data (S2210); - receiving a response from the UE in an inactive state indicating that the UE is ready to receive small data in an inactive state (S2220).

[0199] As already described, the UE 1710 responds by transmitting a response (S1930) to the network node 1760 in response to the notification while remaining in an inactive state. The response is transmitted within a transmission opportunity associated with preconfigured resources. The preconfigured resources include, for example, resources used for the transmission of the RACH procedure and resources assigned to the UE by a Configured Grant (CG) procedure. The transmission opportunity results from the definition and implementation of the above procedures. The RACH procedure, as well as the CG procedure, were described in detail in the above section "Data transmission in the RRC Inactive state of the UE". However, the present disclosure is not limited to the RACH procedure or the CG procedure, and may be any procedure for transmitting a UL response in the inactive state in the future.

[0200] The steps performed by the UE according to the second embodiment, including responding to the network node and receiving small data, may be performed similarly to the first embodiment. Also, the steps performed by the network node according to the second exemplary embodiment, of receiving a response from the UE and transmitting small data, may be performed similarly to the first exemplary embodiment.

[0201] Thus, the response to the paging message may include at least one of a Random Access Small Data Transmission (RA-SDT), a Configured Grant Small Data Transmission (CG-SDT), and a Mobile Terminated Small Data Transmission (MT-SDT).

[0202] In response to the paging message, the UE 1710 may remain in an inactive state and receive small data from the network node 1760. For example, the small data may be a message including a payload, a specific example of which was previously described in the section "Small Data Transmission."

[0203] The received notification is read by the UE, and if it is determined that the DL traffic is a small data transmission, the UE does not need to transition to a connected state.

[0204] The notification to receive the small data may be included in, for example, a paging message or a short message, but the present disclosure is not limited to these examples, and the notification to receive the small data may be included in any of the current messages or messages newly defined in the future that are received by the inactive UE.

[0205] The notification of the SDT may be included in, for example, a paging message (PCCH logical channel) or in, for example, a PagingRecord.

[0206] [Table 6]

[0207] The example PagingRecord includes a signaling field "SDT" that is set to "true" when indicating small data transmission. Note that the illustrated signaling field example is not limited to an ENUMERATED type, and may be another type such as BOOLEAN.

[0208] As mentioned above, a short message may be used to notify the MT-SDT. The short message is transmitted in the PDCCH (e.g., DCI format 1_0) using a P-RNTI with or without an associated paging message. Also, according to Non-Patent Document 8, the Short Message field has a length of 8 bits, and bits 4 to 8 are currently unused. For example, bit 4 may be used to notify the MT-SDT as shown below.

[0209] [Table 7]

[0210] Bit 4 in this example indicates sdtPaging, and in particular, this bit being set to 1 notifies the UE to start the SDT.

[0211] However, the present disclosure is not limited to such an exemplary short message. For example, a different RNTI and / or a different DCI format may be used for the notification of MT-SDT. Such a different RNTI may be an existing RNTI or a new RNTI such as sdt-RNTI.

[0212] Figure 23 shows an implementation procedure in an example according to the second exemplary embodiment. A UE in an RRC_INACTIVE state monitors paging occasions and receives a paging message (S2310). The UE determines whether the paging message includes an SDT notification (S2320). If the paging message includes the above notification ("Yes" in S2320), the UE initiates an SDT and sends a response to the network node (S2330). If the paging message does not include the above notification ("No" in S2320), the UE initiates a resume procedure and transitions to a connected state (S2340).

[0213] Hardware and Software Implementations of the Disclosure The present disclosure can be implemented by software, by hardware, or by software cooperating with hardware. Each functional block used in the description of each embodiment above can be implemented in part or in whole by an LSI such as an integrated circuit, and each process described in each embodiment can be controlled in part or in whole by the same LSI or a combination of LSIs. The LSI can be formed as a chip individually, or a single chip can be formed to include some or all of the functional blocks. The LSI can include a data input / output unit coupled to it. Depending on the degree of integration, the LSI can also be called an IC (integrated circuit), a system LSI, a super LSI, or an ultra LSI. However, the technology for implementing the integrated circuit is not limited to an LSI, and can be implemented by using a dedicated circuit, a general-purpose processor, or a dedicated processor. Furthermore, an FPGA (field programmable gate array) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connections and settings of the circuit cells arranged inside the LSI can also be used. The present disclosure can be implemented as digital processing or analog processing. If, as a result of advances in semiconductor technology or other derivative technologies, LSI is replaced by a future integrated circuit technology, the future integrated circuit technology can be used to integrate the functional blocks. Biotechnology can also be applied.

[0214] The present disclosure may be implemented by any kind of apparatus, device or system having a communication capability (referred to as a communication apparatus).

[0215] The communication device may include a transceiver and processing / control circuitry. The transceiver may include a receiver and a transmitter and / or function as a receiver and a transmitter. The transceiver as a transmitter and a receiver may include an RF (radio frequency) module including an amplifier, an RF modulator / demodulator, etc., and one or more antennas.

[0216] Some non-limiting examples of such communications devices include phones (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (digital audio / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices), game consoles, e-book readers, telehealth / telemedicine equipment, vehicles providing communications capabilities (e.g., cars, airplanes, ships), and various combinations thereof.

[0217] Communications devices are not limited to portable or portable, but can also include any type of equipment, device, or system that is non-portable or fixed, such as smart home devices (e.g., appliances, lights, smart meters, control panels), vending machines, and any other "things" in the "Internet of Things" network.

[0218] Communications may include, for example, exchanging data through cellular systems, wireless LAN systems, satellite systems, etc., as well as various combinations thereof.

[0219] A communications unit may include devices such as a controller or a sensor coupled to the communications device to perform the communications functions described in this disclosure. For example, a communications unit may include a controller or a sensor that generates control or data signals used by the communications device to perform the communications functions of the communications unit.

[0220] The communications apparatus may further include infrastructure facilities, such as base stations, access points, and any other apparatus, devices, or systems that communicate with or control apparatuses such as the apparatuses in the non-limiting examples above.

[0221] Furthermore, various embodiments may be implemented by software modules, which are executed by a processor or directly in hardware. Also, a combination of software modules and hardware implementation is possible. The software modules may be stored in any type of computer-readable storage medium. In particular, according to another implementation, a non-transitory computer-readable storage medium is provided. The storage medium stores a program that, when executed by one or more processors, causes the one or more processors to perform the steps of the method according to the present disclosure.

[0222] By way of non-limiting example, such computer-readable storage media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Also, any connection is referred to as a computer-readable medium, as appropriate. For example, if instructions are transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of the medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but instead cover non-transitory tangible storage media. As used herein, a disk includes a compact disk (CD), a laser disk, an optical disk, a digital versatile disc (DVD), a floppy disk, and a Blu-ray disk, where a "disk" typically reproduces data magnetically, while a "disc" reproduces data optically with a laser. Combinations of the above should also be included within the scope of computer-readable media.

[0223] It should further be noted that individual features of the different embodiments may be the subject of other embodiments individually or in any combination. It will be appreciated by those skilled in the art that the present disclosure set forth in the specific embodiments may be subject to various changes and / or modifications without departing from the concept or scope of the invention as broadly described. The embodiments described herein are therefore to be considered in all respects as illustrative and not restrictive.

[0224] Further aspects According to a first aspect, a User Equipment (UE) is provided. The UE includes a transceiver and a circuit. The circuit, in operation, receives a paging message while in an inactive state. The circuit, in operation, determines to remain in the inactive state for receiving small data in response to the paging message. The circuit, in operation, transmits a response to the paging message to a network node within a transmission opportunity associated with a preconfigured resource while remaining in the inactive state.

[0225] A second aspect is provided in addition to the first aspect, wherein the circuitry, in operation, further receives small data in a Small Data Transmission (SDT) from the network node while remaining in an inactive state.

[0226] A third aspect is provided in addition to the first or second aspect, wherein the small data is a message including a payload or a notification indicating that the UE transitions to a connected state.

[0227] A fourth aspect is provided in conjunction with any one of the first to third aspects, wherein remaining in the inactive state is determined according to a UE configuration.

[0228] A fifth aspect is provided in conjunction with the fourth aspect, wherein a UE configuration is configured for the UE according to a UE capability of the UE.

[0229] A sixth aspect is provided in conjunction with the fourth or fifth aspect, wherein the circuitry, when operated, receives a configuration before transitioning from a connected state to an inactive state and configures a UE configuration according to the configuration.

[0230] A seventh aspect is provided in conjunction with any one of the fourth to sixth aspects, wherein the circuitry, when operational, transmits preferred UE configuration information to a network node while in a connected state.

[0231] An eighth aspect is provided in conjunction with any one of the fourth to seventh aspects, wherein the circuitry, when operated, configures or reconfigures a UE configuration based on a configuration of a radio bearer.

[0232] A ninth aspect is provided in addition to the eighth aspect, wherein the configuration of the radio bearers includes whether all Data Radio Bearers (DRBs) of a plurality of DRBs and / or at least one Signaling Radio Bearer (SRB) of a plurality of SRBs are configured for SDT.

[0233] A tenth aspect is provided in conjunction with any one of the fourth or ninth aspects, wherein the circuitry, when operational, receives a System Information (SI) change notification and configures or reconfigures a UE setting in response to the SI change notification.

[0234] An eleventh aspect is provided in conjunction with any one of the first or tenth aspects, wherein the response to the paging message to the network node comprises: - Random Access Small Data Transmission (RA-SDT), - Configured Grant Small Data Transmission (CG-SDT), or - Mobile Terminated Small Data Transmission (MT-SDT) The present invention includes using at least one of the following:

[0235] According to a twelfth aspect, there is provided a network node comprising a transceiver and a circuit that, when operated, transmits a paging message to a UE in an inactive state and receives a response from the UE in an inactive state indicating that the UE is ready to receive small data in an inactive state.

[0236] A thirteenth aspect is provided in addition to the twelfth aspect, wherein the circuit, when operated, further transmits small data within a Small Data Transmission (SDT) to an inactive UE.

[0237] A fourteenth aspect is provided in conjunction with the twelfth or thirteenth aspect, wherein the small data is a message including a payload or a notification indicating that the UE transitions to a connected state.

[0238] A fifteenth aspect is provided in conjunction with any one of the twelfth or fourteenth aspects, wherein the circuitry receives information relating to a UE configuration.

[0239] A sixteenth aspect is provided in conjunction with any one of the twelfth or fifteenth aspects, wherein the circuitry, when operated, transmits a configuration to the UE before the UE transitions from a connected state to an inactive state.

[0240] A seventeenth aspect is provided in conjunction with any one of the twelfth or sixteenth aspects, wherein the circuitry, in operation, receives preferred UE configuration information from a connected UE.

[0241] An eighteenth aspect is provided in conjunction with any one of the twelfth or seventeenth aspects, wherein the circuitry, when operational, transmits a System Information (SI) change notification including a notification to configure or reconfigure a UE setting.

[0242] A nineteenth aspect is provided in conjunction with any one of the twelfth or eighteenth aspects, wherein the response to the received paging message comprises: - Random Access Small Data Transmission (RA-SDT), - Configured Grant Small Data Transmission (CG-SDT), or - Mobile Terminated Small Data Transmission (MT-SDT) The present invention includes using at least one of the following:

[0243] According to a twentieth aspect, a method for an inactive user equipment (UE) is provided, the method comprising: - receiving a paging message; - determining in response to the paging message to remain in an inactive state for reception of small data; - transmitting a response to the paging message to a network node within a transmission opportunity associated with a pre-configured resource while remaining in the inactive state; Includes.

[0244] According to a twenty-first aspect, there is provided a method for a network node to transmit small data, the method comprising: - transmitting a paging message to the UE in an inactive state; - receiving a response from the UE in the inactive state indicating that the UE is ready to receive the small data in the inactive state; Includes.

[0245] According to a twenty-second aspect, there is provided an integrated circuit that, in operation, controls processing of a user equipment, the processing being performed by the user equipment, - receiving a paging message; - determining in response to the paging message to remain in the inactive state for reception of small data; - transmitting a response to the paging message to a network node within a transmission opportunity associated with a pre-configured resource while remaining in the inactive state; An integrated circuit is provided, comprising:

[0246] According to a twenty-third aspect, there is provided an integrated circuit that, in operation, controls processing of a network node, the processing being performed by the network node, - transmitting a paging message to the UE in an inactive state; - receiving a response from the UE in the inactive state indicating that the UE is ready to receive the small data in the inactive state; An integrated circuit is provided, comprising:

[0247] According to a twenty-fourth aspect, there is provided a program stored on a storage medium and including code instructions, the program, when executed by one or more processors of a user equipment, causing the one or more processors to: - receiving a paging message; - determining in response to the paging message to remain in an inactive state for reception of small data; - transmitting a response to the paging message to a network node within a transmission opportunity associated with a pre-configured resource while remaining in the inactive state; A program is provided to execute the above.

[0248] According to a twenty-fifth aspect, a program stored on a storage medium and including code instructions, which when executed by one or more processors of a network node, causes said one or more processors to: - transmitting a paging message to the UE in an inactive state; - receiving a response from the UE in the inactive state indicating that the UE is ready to receive the small data in the inactive state; A program is provided to execute the above.

[0249] According to a twenty-sixth aspect, a User Equipment (UE) is provided. The UE includes a transceiver and a circuit. In operation, the circuit receives a notification to receive small data from a network node. Upon receiving the notification, the circuit determines to remain in an inactive state of receiving the small data. The circuit remains in an inactive state and transmits a response to the notification to the network node.

[0250] A twenty-seventh aspect is provided in conjunction with the twenty-sixth aspect, wherein the notification is included in a paging message or a short message.

[0251] A 28th aspect is provided in conjunction with the 26th or 27th aspect, wherein the notification is included in a Radio Network Temporary Identifier (RNTI) and / or Downlink Control Information (DCI) and / or in the physical layer on a Physical Downlink Control Channel (PDCCH).

[0252] A 29th aspect is provided in conjunction with any one of the 26th or 28th aspects, wherein the circuitry, in operation, further receives small data within a Small Data Transmission (SDT) from the network node while remaining in an inactive state.

[0253] A 30th aspect is provided in conjunction with any one of the 26th or 29th aspects, wherein the small data is a message including a payload or a notification indicating that the UE transitions to a connected state.

[0254] A thirty-first aspect is provided in conjunction with any one of the twenty-sixth or thirtieth aspects, wherein the response to the paging message to the network node comprises: - Random Access Small Data Transmission (RA-SDT), - Configured Grant Small Data Transmission (CG-SDT), or - Mobile Terminated Small Data Transmission (MT-SDT).

[0255] According to a thirty-second aspect, there is provided a network node. The network node includes a transceiver and a circuit. The circuit, when operated, transmits a notification to receive small data to a UE in an inactive state. The circuit, when operated, receives a response from the UE in an inactive state indicating that the UE is ready to receive small data in an inactive state.

[0256] A thirty-third aspect is provided in conjunction with the thirty-second aspect, wherein the notification is included in a paging message or a short message.

[0257] A thirty-fourth aspect is provided in conjunction with the thirty-second or thirty-third aspects, wherein the circuitry, in operation, remains in an inactive state and further transmits small data within a Small Data Transmission (SDT) from the network node.

[0258] A thirty-fifth aspect is provided in conjunction with one of the thirty-second to thirty-fourth aspects, wherein the small data is a message including a payload or a notification indicating that the UE transitions to a connected state.

[0259] A thirty-sixth aspect is provided in conjunction with any one of the thirty-second to thirty-fifth aspects, wherein the response to the paging message to the network node comprises: - Random Access Small Data Transmission (RA-SDT), - Configured Grant Small Data Transmission (CG-SDT), or - Mobile Terminated Small Data Transmission (MT-SDT) The present invention includes using at least one of the following:

[0260] According to a thirty-seventh aspect, there is provided a method for an inactive user equipment (UE), the method comprising: - receiving a notification to receive small data from a network node; - in response to receiving the notification, determining to remain in the inactive state for reception of the small data; - transmitting to a network node, while remaining in said inactive state, a response to said notification; Includes.

[0261] According to a 38th aspect, there is provided a method for a network node to transmit small data, the method comprising: - sending a notification to an inactive UE to receive small data; - receiving a response from the UE in the inactive state indicating that the UE is ready to receive the small data in the inactive state; Includes.

[0262] According to a thirty-ninth aspect, there is provided an integrated circuit that, in operation, controls processing of a user equipment, the integrated circuit being executed by the user equipment, - receiving a notification to receive small data from a network node; - in response to receiving the notification, determining to remain in an inactive state for receiving the small data; - transmitting to a network node, while remaining in said inactive state, a response to said notification; Includes.

[0263] According to a fortieth aspect, the integrated circuit, in operation, controls the operation of a network node, the operation being performed by the network node comprising the steps of: - sending a notification to an inactive UE to receive small data; - receiving a response from the UE in the inactive state indicating that the UE is ready to receive the small data in the inactive state; Includes.

[0264] According to a forty-first aspect, a program stored on a storage medium and including code instructions, which when executed by one or more processors of a user equipment, causes the one or more processors to: - receiving a notification to receive small data from a network node; - in response to receiving the notification, determining to remain in an inactive state for receiving the small data; - transmitting to a network node, while remaining in said inactive state, a response to said notification; A program is provided to execute the steps including:

[0265] According to a forty-second aspect, a program stored on a storage medium and comprising code instructions, which when executed by one or more processors of a network node, causes the one or more processors to: - sending a notification to an inactive UE to receive small data; - receiving a response from the UE in the inactive state indicating that the UE is ready to receive the small data in the inactive state; A program is provided to execute the steps including:

[0266] In summary, the present disclosure relates to a user equipment (UE), a network node, and a method for the UE and the network node. The UE includes a transceiver and a circuit. In operation, the circuit receives a paging message even in an inactive state. In response to the paging message, the circuit determines to remain in an inactive state for receiving small data. While remaining in the inactive state, the circuit transmits a response to the paging message to the network node at a transmission opportunity associated with a pre-configured resource.

Claims

1. A user equipment (UE), A transmitter / receiver unit; During operation, receiving a paging message while in an inactive state; determining, in response to the paging message, to remain in the inactive state for receiving small data; transmitting a response to the paging message to a network node within a transmission opportunity associated with a pre-configured resource while remaining in the inactive state. The circuit, A UE comprising:

2. and wherein the circuitry, in operation, further receives the small data in a Small Data Transmission (SDT) from the network node while remaining in the inactive state. The UE of claim 1.

3. The small data is a message including a payload or a notification indicating that the UE transitions to a connected state.

3. The UE according to claim 1 or 2.

4. Remaining in the inactive state is determined according to a UE configuration. A UE according to any one of claims 1 to 3.

5. The UE configuration is configured for the UE according to the UE capability of the UE. The UE of claim 4.

6. The circuit, in operation, receiving a configuration and configuring the UE configuration according to the configuration before transitioning from a connected state to the inactive state; 6. The UE according to claim 4 or 5.

7. The circuit, in operation, transmitting preferred UE configuration information to said network node while in a connected state; A UE according to any one of claims 4 to 6.

8. The circuit, in operation, configuring or reconfiguring the UE configuration based on the configuration of the radio bearer; A UE according to any one of claims 4 to 7.

9. The setting of the radio bearer includes whether all of a plurality of data radio bearers (DRBs) and / or at least one of a plurality of signaling radio bearers (SRBs) are set for SDT; The UE of claim 8.

10. The circuit, in operation, Receive a system information (SI) change notification; Configuring or reconfiguring the UE configuration in response to the SI change notification; A UE according to any one of claims 4 to 9.

11. A response to the paging message to the network node, comprising: Random Access Small Data Transmission (RA-SDT), Configured Grant Small Data Transmission (CG-SDT), or Mobile Terminated Small Data Transmission (MT-SDT), A UE according to any one of claims 1 to 10.

12. A network node, A transmitting / receiving unit; During operation, Sending a paging message to the inactive UE; receiving a response from the UE in the inactive state indicating that the UE is ready to receive small data in the inactive state; The circuit, A network node comprising:

13. and wherein, in operation, the circuitry further transmits the small data within a Small Data Transmission (SDT) to the UE in the inactive state. A network node according to claim 12.

14. The small data is a message including a payload or a notification indicating that the UE transitions to a connected state. A network node according to claim 12 or 13.

15. The circuit receives information regarding a UE configuration. A network node according to any one of claims 12 to 14.

16. The circuitry, in operation, transmits a configuration to the UE before the UE transitions from a connected state to an inactive state. A network node according to any one of claims 12 to 15.

17. The circuitry, in operation, receives preferred UE configuration information from the UE in a connected state. A network node according to any one of claims 12 to 16.

18. and transmitting a System Information (SI) change notification, the SI change notification including a notification to configure or reconfigure a UE setting, when the circuitry is operational. A network node according to any one of claims 12 to 17.

19. The received response to the paging message comprises: Random Access Small Data Transmission (RA-SDT), Configured Grant Small Data Transmission (CG-SDT), or Mobile Terminated Small Data Transmission (MT-SDT), A network node according to any one of claims 12 to 18.

19. A method for receiving small data by an inactive user equipment (UE), comprising: receiving a paging message; determining, in response to the paging message, to remain in the inactive state for receiving the small data; transmitting a response to the paging message to a network node within a transmission opportunity associated with a pre-configured resource while remaining in the inactive state; The method includes:

20. A method for a network node to transmit small data, comprising: sending a paging message to the UE in an inactive state; receiving a response from the UE in the inactive state indicating that the UE is ready to receive the small data in the inactive state; The method includes:

21. an integrated circuit which, in operation, controls processing of a user equipment, said processing being performed by said user equipment; receiving a paging message; determining, in response to the paging message, to remain in an inactive state for receiving small data; and transmitting a response to the paging message to a network node within a transmission opportunity associated with a pre-configured resource while remaining in the inactive state. Integrated circuits.

23. an integrated circuit that, in operation, controls processing of a network node, said processing being performed by said network node; sending a paging message to the UE in an inactive state; receiving a response from the UE in the inactive state indicating that the UE is ready to receive small data in the inactive state; Integrated circuits.

24. A program stored on a storage medium and including code instructions, the code instructions, when executed by one or more processors of a user equipment, causing the one or more processors to: receiving a paging message; determining, in response to the paging message, to remain in an inactive state for receiving small data; and transmitting a response to the paging message to a network node within a transmission opportunity associated with a pre-configured resource while remaining in the inactive state. program.

25. A program stored on a storage medium and including code instructions, which when executed by one or more processors of a network node, cause the one or more processors to: sending a paging message to the UE in an inactive state; receiving a response from the UE in the inactive state indicating that the UE is ready to receive small data in the inactive state; program.

26. A user equipment (UE), A transmitter / receiver unit; During operation, Receive a notification to receive small data from a network node; In response to receiving the notification, determining to remain in an inactive state for receiving the small data; transmitting a response to the notification to a network node while remaining in the inactive state; The circuit, A user equipment (UE) comprising:

27. The notification is included in a paging message or a short message.

27. The UE of claim 26.

28. The notification is included in a Radio Network Temporary Identifier (RNTI) and / or Downlink Control Information (DCI) and / or in a physical layer on a Physical Downlink Control Channel (PDCCH), 28. The UE of claim 26 or 27.

29. and wherein the circuitry, in operation, further receives the small data within the Small Data Transmission (SDT) from the network node while remaining in the inactive state. A UE according to any one of claims 26 to 28.

30. The small data is a message including a payload or a notification indicating that the UE transitions to a connected state.

30. The UE according to any one of claims 26 to 29.

31. A response to the paging message to the network node, comprising: Random Access Small Data Transmission (RA-SDT), Configured Grant Small Data Transmission (CG-SDT), or Mobile Terminated Small Data Transmission (MT-SDT), A UE according to any one of claims 26 to 30.

32. A network node, A transmitter / receiver unit; During operation, Sending a notification to an inactive UE to receive small data; receiving a response from the UE in the inactive state indicating that the UE is ready to receive the small data in the inactive state; The circuit, A network node comprising:

33. The notification is included in a paging message or a short message.

33. A network node according to claim 32.

34. and wherein the circuitry, in operation, further transmits the small data within a Small Data Transmission (SDT) from the network node while remaining in the inactive state. A network node according to claim 32 or 33.

35. The small data is a message including a payload or a notification indicating that the UE transitions to a connected state. A network node according to any one of claims 32 to 34.

36. A response to the paging message to the network node, comprising: Random Access Small Data Transmission (RA-SDT), Configured Grant Small Data Transmission (CG-SDT), or Mobile Terminated Small Data Transmission (MT-SDT), A network node according to any one of claims 32 to 35.

37. 1. A method for an inactive user equipment (UE), comprising: receiving a notification to receive small data from a network node; In response to receiving the notification, determining to remain in the inactive state for receiving the small data; transmitting a response to said notification to a network node while remaining in said inactive state; A method comprising:

38. A method for a network node to transmit small data, comprising: sending a notification to a UE in an inactive state to receive small data; receiving a response from the UE in the inactive state indicating that the UE is ready to receive the small data in the inactive state; A method comprising:

39. an integrated circuit that, in operation, controls processing of a user equipment, said processing being performed by said user equipment; receiving a notification to receive small data from a network node; In response to receiving the notification, determining to remain in an inactive state for receiving the small data; transmitting a response to said notification to a network node while remaining in said inactive state; 4. An integrated circuit comprising:

40. an integrated circuit which, in operation, controls processing of a network node, said processing being performed by said network node; sending a notification to a UE in an inactive state to receive small data; receiving a response from the UE in the inactive state indicating that the UE is ready to receive the small data in the inactive state; and an integrated circuit.

41. A program stored on a storage medium and including code instructions, the code instructions, when executed by one or more processors of a user equipment, causing the one or more processors to: receiving a notification to receive small data from a network node; In response to receiving the notification, determining to remain in an inactive state for receiving the small data; and transmitting a response to the notification to the network node while remaining in the inactive state. program.

42. A program stored on a storage medium and including code instructions, which when executed by one or more processors of a network node, cause the one or more processors to: sending a notification to a UE in an inactive state to receive small data; receiving a response from the UE in the inactive state indicating that the UE is ready to receive the small data in the inactive state; program.

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