User equipment and base station involved in the transmission of small data

Abstract

The present disclosure relates to a user equipment UE comprising: a processor determines that small data has become available for transmission using a periodic resource; transmitting the available small data using the periodic resource includes the processor determining a synchronization signal block having a signal quality exceeding a signal quality threshold; if the processor determines that such a synchronization signal block does not exist, the processor operates a time-triggered control mechanism, and the processor controls the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using the periodic resource according to the operated time-triggered control mechanism; the alternative small data transmission mechanism includes one of transmitting the available small data using a random access procedure and performing a cell reselection procedure by the UE to select a new radio cell to transmit the available small data.

Description

[Technical field]

[0001] The present disclosure is directed to methods, apparatus, and articles in communication systems, such as 3GPP® communication systems. [Background technology]

[0002] Currently, the 3rd Generation Partnership Project (3GPP) is working on technical specifications for the next generation of cellular technology, also known as the fifth generation (5G).

[0003] One objective is to provide a single technical framework that addresses all usage scenarios, requirements, and deployment scenarios (e.g., see 3GPP TR 38.913 version 16.0.0, section 6), including at least enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine type communication (mMTC). For example, eMBB deployment scenarios may include indoor hotspots, dense urban, rural, urban macro, and high speed, URLLC deployment scenarios may include industrial control systems, mobile healthcare (remote monitoring, diagnosis, and treatment), real-time control of vehicles, wide area monitoring, and control systems for smart grids, and mMTC deployment scenarios may include scenarios with a large number of devices with non-time-critical data transfer, such as smart wearables and sensor networks. eMBB and URLLC services are similar in that both require very high bandwidth, but differ in that URLLC services may preferably require ultra-low latency.

[0004] A second objective is to achieve forward compatibility: backward compatibility to Long Term Evolution (LTE, LTE-A) cellular systems is not required, thus facilitating the introduction of entirely new system designs and / or novel features. Summary of the Invention

[0005] One non-limiting exemplary embodiment is directed to providing procedures to facilitate a UE to perform improved small data transmissions.

[0006] In one embodiment, the technology disclosed herein features a user equipment UE comprising: a processor of the UE determines that small data has become available for transmission; the available small data is transmitted using a periodic resource without a prior scheduling request from the UE; transmitting the available small data using the periodic resource includes the processor determining one of a plurality of synchronization signal blocks having a signal quality that exceeds a signal quality threshold; if the processor determines that no synchronization signal block has a signal quality that exceeds the signal quality threshold, The processor, during operation, operates a time-triggered control mechanism; During operation, the processor controls the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using the periodic resource according to the activated time-triggered control mechanism. Alternative small data transmission mechanisms include: transmitting, by a transmitter of the UE, the available small data using a random access procedure; performing, by the UE, a cell reselection procedure for selecting a new radio cell for transmitting the available small data; Contains one of the following:

[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, an 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. These benefits and / or advantages may be obtained individually by the various embodiments and features of the specification and drawings, and it is not necessary for all of the embodiments and features to be provided in order to obtain one or more of such benefits and / or advantages. [Brief description of the drawings]

[0009] The following embodiments are explained in more detail with reference to the accompanying drawings. [Figure 1] FIG. 1 is an example architecture diagram of a 3GPP NR system. [Diagram 2] Schematic showing the functional separation between NG-RAN and 5GC [Diagram 3] Sequence diagram of RRC connection setup / reconfiguration procedure [Figure 4] Schematic diagram 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 example 5G system architecture for a non-roaming scenario [Figure 6] Diagram showing contention-based and contention-free RACH procedures [Figure 7] Diagram showing contention-based and contention-free RACH procedures [Figure 8] Diagram showing possible RRC state changes [Figure 9]FIG. 2 illustrates a prior art message exchange for uplink data transmission involving a UE state change from an inactive state to a connected state. [Figure 10] A diagram showing an example 4-step RACH that can be used for small data uplink transmissions for RRC_INACTIVE UEs. [Figure 11] FIG. 1 illustrates an example two-step RACH that can be used for small data uplink transmissions for RRC_INACTIVE UEs. [Figure 12] A diagram showing configured grant resources and two UEs that use the configured grant resources for transmitting small data. [Figure 13] A diagram showing beam transmission by gNB, each of which includes SSB. [Figure 14] FIG. 1 is a diagram of an exemplary simplified structure of a UE and a gNB. [Figure 15] A diagram showing the structure of a UE according to an exemplary implementation of an improved small data transmission procedure. [Figure 16] 1 is a flow diagram of a UE operation according to an example implementation of an improved small data transmission procedure. [Figure 17] A diagram showing the structure of a base station according to an exemplary implementation of an improved small data transmission procedure. [Figure 18] 4 is a flow diagram of base station operations involved in an exemplary implementation of an improved small data transmission procedure. [Figure 19] FIG. 1 is a signaling diagram illustrating an exemplary exchange between a UE and a gNB regarding the implementation of an improved small data transmission procedure. [Figure 20] 1 is a flow diagram of UE operation according to a first timer-based implementation of the improved small data transmission procedure. [Figure 21] A diagram showing UE operation of a first timer-based implementation of configured grant resources, alternative small data transmission random access opportunities, and an improved small data transmission procedure in a scenario where small data is ultimately transmitted using periodic resource occasions. [Figure 22] A diagram showing UE operation of configuring grant resources, alternative small data transmission random access opportunities, and a first timer-based implementation of an improved small data transmission procedure in a scenario where small data is ultimately transmitted in an alternative manner using a random access opportunity. [Diagram 23] 13 is a flowchart of UE operation according to a second counter-based implementation of the improved small data transmission procedure. [Figure 24] A diagram showing UE operation of configured grant resources, alternative small data transmission random access opportunities, and a second counter-based implementation of an improved small data transmission procedure in a scenario where small data is ultimately transmitted using periodic resource opportunities. [Diagram 25] A diagram showing UE operation of configured grant resources, alternative small data transmission random access opportunities, and a second counter-based implementation of an improved small data transmission procedure in a scenario where small data is ultimately transmitted in an alternative manner using a random access opportunity. [Figure 26] 11 is a flow diagram of UE operation according to a third timer and counter based implementation of the improved small data transmission procedure. [Figure 27] 13 is a flowchart of UE operation according to a fourth period-based implementation of the improved small data transmission procedure. [Figure 28] A diagram showing UE operation of configured grant resources, alternative small data transmission random access opportunities, and a fourth period-based implementation of an improved small data transmission procedure in a scenario where small data is transmitted in an alternative manner using random access opportunities. [Figure 29] A diagram showing UE operation of a fourth period-based implementation of configured grant resources, alternative small data transmission random access opportunities, and an improved small data transmission procedure in a scenario in which small data is transmitted in an alternative manner using a random access opportunity after the end of the period. [Diagram 30]A diagram showing UE operation of a fourth period-based implementation of configured grant resources, alternative small data transmission random access opportunities, and an improved small data transmission procedure in a scenario in which small data is transmitted using periodic resource opportunities during the period. [Diagram 31] 13 is a flow diagram of UE operation according to another implementation of the improved small data transmission procedure in which the UE determines an SSB-specific signal quality threshold against which the SSB quality is compared. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <5G NR system architecture and protocol stack> 3GPP continues to work on the next release of fifth-generation cellular technology (also known simply as "5G"), which includes the development of New Radio Access Technology (NR) that will operate in the frequency range up to 100 GHz. The first version of the 5G standard was completed in late 2017, allowing for the prototyping and commercial deployment of 5G NR-compliant smartphones.

[0011] In particular, the overall system architecture assumes a Next Generation-Radio Access Network (NG-RAN) with gNBs. The gNBs provide the UE-side termination of the 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 the Next Generation Core (NGC) by a Next Generation (NG) interface, more specifically to the Access and Mobility Management Function (AMF, e.g. a specific core entity running AMF) by an NG-C interface and to the User Plane Function (UPF, e.g. a specific core entity running UPF) by an NG-U interface. The NG-RAN architecture is shown in Figure 1 (see, e.g., section 4 of 3GPP TS 38.300 v16.46.0).

[0012] The NR user plane protocol stack (see, for example, section 4.4.1 of 3GPP TS 38.300) includes the PDCP (Packet Data Convergence Protocol, see section 6.4 of TS 38.300) sublayer, the RLC (Radio Link Control, see section 6.3 of TS 38.300) sublayer, and the MAC (Medium Access Control, see section 6.2 of TS 38.300) sublayer, which are terminated on the network side at the gNB. In addition, a new Access Stratum (AS) sublayer (SDAP: Service Data Adaptation Protocol) is introduced above PDCP (see, for example, sub-clause 6.5 of TS 38.300). NR also defines a control plane protocol stack (see, for example, section 4.4.2 of TS 38.300). An overview of Layer 2 functions is given in sub-clause 6 of TS 38.300. The functions of the RRC layer are listed in sub-clause 7 of TS 38.300.

[0013] For example, the MAC layer is responsible for multiplexing logical channels and scheduling and scheduling-related functions, including handling 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. It also maps 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) in the uplink, and PDSCH (Physical Downlink Shared Channel), PDCCH (Physical Downlink Control Channel), and PBCH (Physical Broadcast Channel) in the downlink.

[0015] NR use cases / deployment scenarios include eMBB (enhanced Mobile Broadband), URLLC (Ultra-Reliable Low-Latency Communications), and mMTC (massive Machine Type Communication), which have diverse requirements for data rate, latency, and coverage. For example, eMBB is required to support peak data rates (20Gbps downlink, 10Gbps uplink) and effective (user-experienced) data rates that are about three times higher than those offered by IMT-Advanced. On the other hand, URLLC has more stringent requirements for ultra-low latency (user plane latency of 0.5ms for both UL and DL) and high reliability (1-10 Mbps latency within 1ms). -5Finally, mMTC preferably requires high connection density (1 million devices per square kilometer in urban environments), wide coverage in adverse environments, and ultra-long battery life (15 years) for low-cost equipment.

[0016] Therefore, OFDM numerology (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) suitable for one use case may not be valid for other use cases. For example, low latency services may preferably require a shorter symbol length (and therefore a larger subcarrier spacing) and / or fewer symbols per scheduling interval (in other words, TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP length than scenarios with small delay spreads. To maintain similar CP overhead, the subcarrier spacing needs to be optimized accordingly. NR may support multiple values ​​of subcarrier spacing. Correspondingly, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, ... are currently being considered. Symbol length T u and the subcarrier spacing Δf is expressed by the formula Δf=1 / T u Similar to 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 the uplink and downlink, respectively. Each element of 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 3GPP TS 38.211 v16.46.0, e.g., section 4). For example, downlink and uplink transmissions are organized into frames with a duration of 10 ms, each frame consisting of 10 subframes of 1 ms duration each. In a 5g NR implementation, the number of consecutive OFDM symbols per subframe depends on the subcarrier spacing setting. For example, for a subcarrier spacing of 15 kHz, a subframe has 14 OFDM symbols (similar to an LTE-compatible implementation assuming a normal cyclic prefix). On the other hand, for a subcarrier spacing of 30 kHz, a subframe has two slots, each slot containing 14 OFDM symbols.

[0018] <Functional separation between NG-RAN and 5GC in 5G NR> Figure 2 shows the functional separation between NG-RAN and 5GC. The logical node of NG-RAN is gNB or ng-eNB. 5GC has logical nodes AMF, UPF, and SMF.

[0019] In particular, the gNB and ng-eNB host the following main functions: - Radio Resource Management functions such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, dynamic allocation (scheduling) of resources to UEs in both uplink and downlink; - IP header compression, encryption, and integrity protection of data; - Selection of the AMF at UE attach time if routing to the AMF cannot be determined from information provided by the UE; - Routing of user plane data towards the UPF; - Routing of control plane information towards AMF; - Setting up and tearing down connections; - Scheduling and sending paging messages; - Scheduling and transmission of system broadcast information (sourced from AMF or Operation, Admission, Maintenance Function (OAM)); - Setting up measurements and reporting of measurements for mobility and scheduling; - Transport level packet marking in the uplink; - Session management; - Support for network slicing; - QoS flow management and mapping to data radio bearers; - Support for UEs in RRC_INACTIVE state; - Non-Access Stratum (NAS) message delivery function; - Sharing of radio access networks; - Dual connectivity; - Close cooperation between NR and E-UTRA.

[0020] The Access and Mobility Management Function (AMF) hosts the following main functions: - Termination of Non-Access Stratum (NAS) signalling; - NAS signaling security; - Access Layer (AS) security controls; - 3GPP Core Network (CN) inter-node signalling for mobility between access networks; - Reachability to idle mode UEs (including control and execution of paging retransmissions); - Managing the registration area; - Support for intra-system and inter-system mobility; - Access authentication; - Access authorization including roaming privilege checks; - Mobility management control (subscription and policies); - Support for network slicing; - Selection of Session Management Function (SMF).

[0021] Additionally, the User Plane Function (UPF) hosts the following main functions: - Anchor points for intra-RAT / inter-RAT mobility (if applicable); - External PDU (Protocol Data Unit) Session Points for interconnection with data networks; - Packet routing and forwarding; - Packet inspection and policy rule enforcement for the user plane part; - Traffic usage reporting; - an uplink classifier that supports routing of traffic flows to the data network; - Branching Point to support multi-homed PDU sessions; - QoS processing for the user plane (e.g., packet filtering, gating, UL / DL rate enforcement); - Validation of uplink traffic (mapping of SDF to QoS flows); - Downlink packet buffering and downlink data notification triggering.

[0022] Finally, the Session Management Function (SMF) hosts the following main functions: - Session management; - IP address allocation and management for the UE; - Selection and control of the UPF; - Traffic steering setting function in the User Plane Function (UPF) for routing traffic to the appropriate destination; - Policy enforcement and QoS for the control plane; - Notification of downlink data.

[0023] <Procedures for RRC connection setup and reconfiguration> Figure 3 shows some of the interactions between the UE, gNB, and AMF (5GC entity) in the NAS part when the UE moves from RRC_IDLE to RRC_CONNECTED (see TS 38.300).

[0024] RRC is a higher layer signaling (protocol) used for the configuration of the UE and the gNB. In particular, with this transition, the AMF prepares UE context data (which includes, for example, PDU session context, security keys, UE Radio Capability, UE Security Capabilities, etc.) and sends it to the gNB with an INITIAL CONTEXT SETUP REQUEST. The gNB then activates AS security together with the UE. This is done 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 reconfiguration to set up signaling radio bearer 2 (SRB2) and data radio bearer (DRB) by sending an RRCReconfiguration message to the UE and receiving an RRCReconfigurationComplete from the UE. For signaling-only connections, the steps related to RRCReconfiguration are omitted since SRB2 and DRB are not set up. Finally, the gNB informs the AMF that the setup procedure is complete with an INITIAL CONTEXT SETUP RESPONSE.

[0025] Therefore, the present disclosure provides an entity (e.g., AMF, SMF, etc.) of a 5th Generation Core (5GC), comprising: a control circuit that operatively establishes a Next Generation (NG) connection with a gNodeB; and a transmitter that operatively transmits an initial context setup message to the gNodeB via the NG connection such that a signaling radio bearer between the gNodeB and a User Equipment (UE) is set up. Specifically, the gNodeB transmits Radio Resource Control (RRC) signaling including a resource allocation configuration information element (IE) to the UE via the signaling radio bearer. Then, the UE transmits in uplink or receives in downlink based on the resource allocation configuration.

[0026] <IMT usage scenarios after 2020> Figure 4 shows some of the use cases for 5G NR. The 3rd Generation Partnership Project NR (3GPP NR) is considering three use cases that are expected to support a wide variety of services and applications with IMT-2020. The first phase of specifications for enhanced Multimedia Broadcasting (eMBB) has been completed. In addition to further expanding support for eMBB, current and future research is also being conducted on the standardization of ultra-reliable low latency (URLLC) and multiple simultaneous connections. Figure 4 shows examples of usage scenarios that are expected for IMT beyond 2020 (see, for example, Figure 2 in ITU-R M.20183).

[0027] URLLC use cases have stringent performance requirements such as throughput, latency, and availability, and are envisioned as one of the enablers of future vertical applications such as wireless control of industrial production and manufacturing processes, remote medical surgery, power distribution automation for smart grids, and road safety. URLLC's ultra-high reliability is supported by identifying technologies that meet the requirements set by TR 38.913v16.0.0. For NR URLLC in Release 15, the key requirement is to target user plane latency of 0.5 ms UL (uplink) and 0.5 ms DL (downlink). The general URLLC requirement for a single packet transmission is a block error rate (BLER) of 1E-5 for a packet size of 32 bytes with a user plane latency of 1 ms.

[0028] From a physical layer perspective, reliability can be improved in many possible ways. Current room for reliability improvement includes defining a separate CQI table for URLLC, more compact DCI formats, repeated transmission of PDCCH, etc. However, this room can be expanded to achieve ultra-high reliability as NR (with respect to the key requirements of NR URLLC) becomes more stable and more developed. Specific use cases for NR URLLC in Release 15 include augmented reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0029] Also, technology extensions targeted by NR URLLC aim to improve latency and reliability. Technology extensions for improving latency include configurable numerology, non-slot-based scheduling with flexible mapping, grant-free (configurable grant) uplink, repeated transmissions at slot level in data channel, and pre-emption in downlink. Pre-emption means that a transmission with already allocated resources is stopped and the already allocated resources are used for other transmissions with lower latency / higher priority requirements that are requested later. Thus, a transmission that was already allowed is preempted by a later transmission. Pre-emption is applicable 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 extensions for improving reliability include dedicated CQI / MCS tables for a target BLER of 1E-5.

[0030] The mMTC (Massive Machine Type Communication) use case is characterized by a very large number of connected devices that typically transmit relatively small amounts of data that are not sensitive to latency. The devices are required to be low cost and have very long battery life. From an NR perspective, the use of very narrow bandwidth portions is one solution that saves power from the UE's perspective and allows for long battery life.

[0031] As mentioned above, it is expected that the scope of reliability improvement in NR will be broader. One of the key requirements for all cases, especially for URLLC and mMTC, is high or ultra-high reliability. Several mechanisms can be considered that can improve reliability from a radio perspective and a network perspective. In general, there are two to three key areas that can help improve reliability. These areas include compact control channel information, repeated transmission of data channel / control channel, and diversity with respect to frequency domain, time domain, and / or spatial domain. These areas are generally applicable to reliability improvement regardless of the specific communication scenario.

[0032] Further use cases with more stringent requirements are envisaged for NR URLLC, such as factory automation, transportation, and power distribution. The stringent requirements include high reliability (10 6 level of reliability), high availability, packet size up to 256 bytes, time synchronization up to a few μs (depending on the use case, the value can be 1 μs or a few μs depending on the frequency range and short latency on the order of 0.5 ms to 1 ms (in particular, a targeted latency of 0.5 ms on the user plane).

[0033] Furthermore, for NR URLLC, several technical extensions are possible from the perspective of the physical layer. These technical extensions include the extension of the Physical Downlink Control Channel (PDCCH) related to compact DCI, the repeated transmission of PDCCH, and the increase in the monitoring of PDCCH. Also, the extension of UCI (Uplink Control Information) is related to the extension of enhanced HARQ (Hybrid Automatic Repeat Request) and CSI feedback. In addition, there may be extensions of PUSCH related to hopping at the mini-slot level, and extensions of retransmission / repeated transmission. The term "mini-slot" refers to a transmission time interval (TTI) that contains fewer symbols than a slot (a slot contains 14 symbols).

[0034] <QoS Control> The QoS (Quality of Service) model of 5G is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (GBR (Granteed Bit Rate) 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-grained QoS differentiation in a PDU session. A QoS flow is identified within a PDU session by a QoS Flow ID (QFI: QoS Flow ID) that is carried in an encapsulation header via the NG-U interface.

[0035] For each UE, the 5GC establishes one or more PDU sessions. For each UE, the NG-RAN establishes at least one Data Radio Bearer (DRB) for the PDU session, e.g. as shown above with reference to Fig. 3. Additional DRBs for the QoS flows of the PDU session can be configured later (when it is up to the NG-RAN). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. The NAS level packet filters in the UE and the 5GC associate UL and DL packets with QoS flows, whereas the AS level mapping rules in the UE and the NG-RAN associate UL and DL QoS flows with DRBs.

[0036] FIG. 5 shows a non-roaming reference architecture for 5G NR (see, for example, 3GPP TS 23.501 v16.7.0 or v16.7.1.1, section 4.2.3). An application function (AF), such as an external application server hosting a 5G service, as illustrated in FIG. 4, interacts with the 3GPP core network to provide the service. For example, it may access a network exposure function (NEF) to support applications that affect traffic routing, and interact with a policy framework for policy control such as QoS control (see Policy Control Function (PCF)). Based on the operator's deployment, application functions that are deemed trusted by the operator may directly interact with the relevant network functions. Application functions 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.

[0037] Figure 5 further illustrates further functional units of the 5G architecture, namely, 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-provided services, Internet access, or third-party services). All or part of the core network functions and application services may be deployed and run in a cloud computing environment.

[0038] Therefore, the present disclosure provides an application server (e.g., an AF in a 5G architecture) comprising: a transmitter that, in operation, sends a request including QoS requirements for at least one of a URLLC service, an eMBB 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 according to the QoS requirements; and a control circuit that, in operation, performs a service using the established PDU session.

[0039] <Random access procedure> Similar to LTE, 5G NR provides a RACH (Random Access Channel) procedure (or simply a random access procedure). For example, the RACH procedure can be used by a UE to access a cell that the UE has found. The RACH procedure can also be used in other contexts within 5G NR, such as: For handover when establishing synchronization to a new cell; To re-establish uplink synchronization to the current cell when synchronization has been lost due to the absence of any uplink transmissions from the device for too long; To request uplink scheduling when no dedicated scheduling request resources for the device are configured.

[0040] There are a number of events that can cause a UE to trigger a random access procedure (see 3GPP TS 38.300, v16.6.0 section 9.2.6), including: The random access procedure is triggered by a number of events, such as: - Initial access from RRC_IDLE; - RRC connection re-establishment procedure; - arrival of DL or UL data during RRC_CONNECTED when the UL synchronization state is "asynchronous"; - UL data arrival during RRC_CONNECTED when there are no PUCCH resources for the SR available; - SR failure; - requested by RRC during synchronous reconfiguration (e.g. handover); - Transition from RRC_INACTIVE; - Establishing time alignment to the secondary TAG; - other SI requirements (see section 7.3); - Beam obstruction recovery; -Continued UL LBT failures in SpCell.

[0041] If the mobile terminal's uplink transmission is time synchronized, the mobile terminal can be scheduled for uplink transmission. Thus, the random access channel (RACH) procedure serves as an interface between asynchronous mobile terminals (UEs) and orthogonal transmission of uplink radio access. For example, the random access procedure is used to realize uplink time synchronization for user equipment that has not yet acquired or lost uplink synchronization. Once the user equipment realizes uplink synchronization, the base station can schedule uplink transmission resources for the user equipment. One scenario related to random access is a scenario in which 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 realize uplink time synchronization in the target cell.

[0042] There can be at least two types of random access procedures: access can be either contention based (meaning an inherent risk of collision) or contention free (non-contention based). An exemplary definition of a random access procedure can be found in 3GPP TS 38.321, v16.5.0 Section 5.1.

[0043] The RACH procedure is described in more detail below with reference to Figures 6 and 7. In the following, the contention-based random access procedure is described in more detail with respect 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 (i.e., message 1 of the RACH procedure) to the base station on the Physical Random Access Channel (PRACH). After the base station detects the RACH preamble, it transmits a Random Access Response (RAR) message (message 2 of the RACH procedure) on the Physical Downlink Shared Channel (PDSCH) addressed in the PDCCH containing a (random access) RA-RNTI identifying the time-frequency and slot in which the preamble was detected. If multiple user equipments transmit the same RACH preamble on the same PRACH resource (also called collision), they may 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 transmitting the first Scheduled Transmission, and an allocation of a Temporary Cell Radio Network Temporary Identifier (T-CRNTI) that is used by the base station to address the mobile terminal for which the RACH preamble was detected until the RACH procedure is finished, since at the time of detection of the RACH preamble the "real" identity of the mobile terminal is not yet known to the base station.

[0044] The user equipment monitors the PDCCH for reception of a random access response message within a given 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 an actual message with a specific function, such as an RRC connection request, an RRC resumption request, or a buffer status report.

[0045] 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 their scheduled transmissions in the third step of the RACH procedure. If the base station is able to decode the scheduled transmission from one user equipment, the contention remains open for the other user equipment. For the resolution of 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.

[0046] Figure 7 shows a non-contention 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 use for random access, so that there is no risk of collision (i.e., no risk of multiple user equipments transmitting the same preamble). Thus, the user equipment then transmits the preamble signaled by the base station in the uplink of the PRACH resource. For non-contention random access, the case where multiple UEs transmit the same preamble is avoided, so that the non-contention random access procedure is essentially completed after the UE successfully receives the random access response.

[0047] 3GPP also defines a two-step (contention-based) RACH procedure for 5G NR, where message 1 (named MsgA), which corresponds to messages 1 and 3 of the four-step LTE / NR RACH procedure, is transmitted first for the two-step RACH type. MsgA includes a preamble in the Physical Random Access Channel (PRACH) and a payload in 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 then responds with message 2 (called MsgB), which corresponds to messages 2 and 4 of the four-step LTE / NR RACH procedure. This MsgB may include, for example, a Success Random Access Response (Success RAR), a Fallback RAR, and optionally a backoff notification. Upon receiving a Success RAR and successful contention resolution, the UE terminates the random access procedure. Upon receiving fallback RAR in MsgB, the UE performs transmission of message 3 (similar to the 4-step RACH procedure) and monitors contention resolution. Some further exemplary assumptions are made for the 2-step RACH procedure, such that after determining the RACH type (e.g., 2-step RACH), the UE keeps retrying the same RACH type until it fails. However, it may also be possible that the UE can switch to the 4-step RACH procedure after a certain number of retries of MsgA transmission.

[0048] Furthermore, the network can 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 to transmit the first message in the RACH procedure include at least a RACH opportunity 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 opportunity and the preamble) but also the associated PUSCH resource.

[0049] Generally, for the RACH preamble, refer to, for example, 3GPP TS 38.211 V16.6.0, "Table 6.3.3.2-2: Random access configurations for FR1 and paired spectrum / supplementary uplink" and Section 6.3.3.2, "Mapping to physical resources".

[0050] <RRC state (RRC_Connected, RRC_Inactive)> In LTE, the RRC state machine consists of only two states, namely the RRC idle state (characterized mainly by high power saving, autonomous mobility of the UE, and the lack of established connectivity of the UE to the core network) and the RRC connected state. A UE in the RRC connected state can transmit user plane data, while mobility is network-controlled to support seamless service continuity. In relation to 5G NR, as described below, the RRC state machine for LTE is extended by the inactive state (see, for example, TS 38.331 v16.3.1, Figures 4.2.1-1, 1-2).

[0051] RRC in NR 5G (see Section 4 of TS 38.331) supports the following three states: the RRC idle state, the RRC inactive state, and the RRC connected state. When an RRC connection is established, the UE is in either the RRC_CONNECTED state or the RRC_INACTIVE state. When this is not the case, 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. - A state transition from RRC_IDLE to RRC_CONNECTED, for example, following a "connection establishment" procedure; - state transition, e.g. from RRC_CONNECTED to RRC_IDLE following a "disconnect" procedure; - state transition, e.g. from RRC_CONNECTED to RRC_INACTIVE following a "Disconnect with suspend" procedure; - state transition, e.g. from RRC_INACTIVE to RRC_CONNECTED following a "connection resumption" procedure; - A state transition, e.g. from RRC_INACTIVE to RRC_IDLE (unidirectional) following a "Disconnect" procedure.

[0052] A new RRC state, the RRC Inactive state, is defined for 5G 3GPP new radio technologies and provides benefits when supporting a wider range of services such as enhanced Mobile Broadband (eMBB), Massive Machine Type Communications (mMTC), Reliable Ultra Low Latency Communications (URLLC), etc., which have significantly different requirements in terms of signaling, power saving, latency, etc. The new RRC Inactive state is therefore designed to make it possible to minimize signaling, power consumption, and resource costs in the radio access network and core network, while still making it possible to initiate data transfer with low latency, for example.

[0053] In accordance with an exemplary 5G NR implementation, these different states are defined in section 4.2.1 of TS38.331, with the RRC_INACTIVE state defined as follows: "RRC_INACTIVE: - UE-specific DRX may be configured by higher layers or the RRC layer. - UE controlled mobility based on network configuration. - The UE stores the UE inactive AS context. - RAN-based notification areas are configured by the RRC layer. The UE: - monitor short messages sent with P-RNTI via DCI (see clause 6.5); - Monitor the paging channel for CN paging using 5G-S-TMSI and RAN paging using full I-RNTI. - Perform neighbor cell measurements and cell (re)selection. - Perform RAN-based notification area updates periodically and when moving outside the configured RAN-based notification area. - Able to get system information and send SI requests (if configured). - perform logging of available measurements with location and time for logged measurement configured UEs; - Perform idle / inactive measurements for UEs configured for idle / inactive measurements. "

[0054] The RRC inactive state feature maintains connectivity (both user plane and control plane) with the RAN and core network for an inactive UE.

[0055] <Synchronization signal block measurement timing setting (SMTC)-PSS / SSS, PBCH> NR introduces the so-called synchronization signal block, SS block (SSB), which includes the Primary Synchronization Signal (PSS), the Secondary Synchronization Signal (SSS), and the Physical Broadcast CHannel (PBCH). The PSS and SSS can be used by the UE to discover, synchronize to, and identify the network. The PBCH carries minimal system information, including an indication where the rest of the broadcast system information is transmitted. In LTE, these three signals PSS, SSS, and PBCH were also used, but not as part of one SSB.

[0056] In NR, these three SSB components are always transmitted together, e.g., they have the same periodicity. A given SSB may be repeated within an SS burst set, which may be used for gNB beam sweeping transmissions in some cases. The SS burst set may be limited to a particular period, e.g., a 5 ms window. For initial cell selection, the UE may assume a default SS burst set periodicity of 20 ms.

[0057] The 5G NR PSS is a physical layer specific signal for identifying radio frame boundaries and is a type of m-sequence. The 5G NR SSS is a physical layer specific signal for identifying subframe boundaries and is also an m-sequence (see, for example, TS38.211 v16.6.0 Sections 7.4.2 and 7.4.3).

[0058] <Settings grant, grant-free access, grant-free uplink> Uplink data transmission typically requires resource requests by the UE, followed by a packed scheduling decision and resource allocation at the scheduler (e.g., base station). The allocation cycles cause additional delays and signaling. The delay in radio resource allocation between the UE and the base station can be avoided by allowing the UE to use the radio resources without requesting them from the base station in advance.

[0059] LTE introduced the semi-persistent-scheduling (SPS) feature, which is especially useful for periodic data transmissions such as Voice over IP (VoIP) services. The base station configures SPS radio resources, and the UE can use these periodic radio resources without an additional scheduling request procedure. However, the SPS configuration in LTE is dedicated to a single device. If the device does not require the assigned periodic resources (e.g., data is transmitted only for certain events such as collision warnings), the SPS resources not used by the UE are wasted.

[0060] 5G NR introduces grant-free access, also known as transmission without grant (TWG), which allows the UE to transmit data without prior scheduling (e.g., without the UE sending a corresponding resource request). This approach may also allow for minimizing latency and the respective signaling.

[0061] Furthermore, multiple devices (UEs) may be allowed to share the periodic radio resource, which is called configured grant (CG) (this facilitates reducing waste of the periodic radio resource compared to SPS in LTE). On the other hand, the gNB may define the periodic radio resource such that it is not shared or is not shared completely 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.

[0062] Two types of grant-free configuration schemes are supported in 3GPP Release 16: Type 1 and Type 2 (see 3GPP38.300v16.6.0: "NR; NR and NG-RAN Overall Description; Stage 2 (Release 16)", section 10.3).

[0063] According to this exemplary implementation of TS38.300, the RRC uses Type 1 CG to provide configuration uplink grants, including, for example, periodicities, directly to one or more UEs.

[0064] In type 2 configuration grants, the RRC defines the periodicity of the configuration uplink grants, but a PDCCH message addressed to the CS-RNTI of one or more UEs can signal the configuration uplink grants to activate or deactivate them, and the PDCCH addressed to the CS-RNTI indicates that the uplink grants can be implicitly reused according to the periodicity defined by the RRC until they are 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 a (de)activation DCI. The RRC provides higher layer parameters for the CG configuration.

[0065] 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 TS38.331v16.5.0, section 6.3.2 "Radio resource control information elements").

[0066] The resource configuration of CG may include physical resources in the time domain and / or frequency domain, and / or reference signal (RS) parameters. The configuration parameters may further include modulation and coding scheme (MCS), and / or the number of repetitions, and / or the repetition period, and / or the transport block size.

[0067] <Small-scale data transmission> In the present disclosure, the characteristics of the small-scale data transmission targeted refer to any service having the characteristics that the data burst in UL / DL is small without strict requirements for delay, and optionally, the data burst is quite infrequent. For example, a single data transmission small enough for a UE to transmit in one transmission (e.g., in RACH or in one CG opportunity, see below) can be regarded as small-scale data transmission. The following table summarizes typical non-limiting examples of the traffic characteristics of small-scale data transmission (see Section 5 of TR25.705 v13.0.0).

Table 1

[0068] Another different possible exemplary definition may depend on the configuration of the gNB. For example, the gNB may define that data less than a specific threshold (e.g., 1000 kilobytes) is regarded as small-scale data, while data exceeding that threshold is not regarded as small-scale data. This threshold may be defined, for example, in relation to the buffer state of the UE.

[0069] Alternatively, the definition of what small-scale data is may be fixed by an appropriate 3GPP standard (specification) that provides, for example, a data volume threshold similar to the above.

[0070] <Small-scale data transmission by a UE in the RRC inactive state> More specifically, 5G NR supports the RRC_INACTIVE state, and UEs with infrequent (periodic and / or aperiodic) data transmissions are typically kept in the RRC_INACTIVE state by the network. Until Rel-16, the RRC_INACTIVE state does not support data transmission. Thus, the UE needs to resume the connection (e.g., go to RRC_CONNECTED state) for any DL (MobileTerminated) and UL (MobileOriginated) data. Connection setup (or resumption) and subsequent release to the RRC_INACTIVE state would need to be done for each data transmission, no matter how small and infrequent the data packets are. This results in unnecessary power consumption and signaling overhead.

[0071] Furthermore, the 3GPP RP-193252 document, which is a description of the 3GPP work item on NR small data, provides the following specific examples of small and infrequent data traffic in the sense of small data, including the following use cases: - Smartphone application: Traffic from instant messaging services (e.g. WhatsApp, QQ, WeChat) Heartbeat / keep-alive traffic from IM / email clients and other apps Push notifications from various applications - Non-smartphone applications: Traffic from wearables (such as periodic positioning information) Sensors (such as industrial wireless sensor networks that transmit temperature and pressure measurements periodically or in an event-triggered manner) Smart meters and smart meter networks that transmit periodic meter readings

[0072] Small data transmissions can support a variety of different packet sizes and can have different traffic requirements.

[0073] 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 sending periodic meter readings, 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 to 128 bytes. Instant messages (traffic patterns are not deterministic) can send text, photos, videos, etc., and the packet size varies from 100 bytes to 1000 bytes. For push notifications, the traffic patterns are not deterministic and different applications generate highly diverse message sizes.

[0074] An exemplary procedure of the prior art (in this case a 5G-NR compliant prior art solution) that allows a UE in an RRC Inactive state to transmit (small) data after transitioning to an RRC Connected state is briefly described below with reference to Figure 9. As is evident from the figure, it is assumed that the UE is in an RRC_Inactive state, which may include, for example, that all data radio bearers of the UE (and the gNB) are suspended and that no data can be transmitted to the gNB. To allow the UE to transmit data, it must first be transitioned to an RRC Connected state, which can be done, for example, by the UE requesting resumption of the RRC connection (here sending an RRCResumeRequest) as part of a RACH procedure (in Figure 9, for example, using a four-step RACH procedure).

[0075] In detail, the UE may send a preamble to the serving gNB and then receive a corresponding Random Access Response with a (small) UL grant of radio resources, which the UE uses to send a RRCResumeRequest message as msg3 of the RACH procedure.

[0076] Finally, the new gNB provides an RRCResume message to the UE, and then the UE moves to an RRC connected state, which includes the resumption of all data radio bearers. In the RRC_Connected state, the UE can then transmit UL (small) data.

[0077] It is not yet defined when and how the gNB decides that the UE should actually transition to the RRC_CONNECTED state. The control in this regard is likely still up to the gNB, even though the UE may request to resume the RRC connection. One exemplary possibility is that the gNB takes into account a buffer status report that the UE may send, for example in Msg3 or MsgA, to decide whether the UE should transition to the RRC_CONNECTED state or not. The buffer status report indicates the actual amount of data in the UE buffer. For example, if the buffer status report indicates a large amount of data in the UE buffer, the gNB may decide to transition the UE from the RRC_INACTIVE state to the RRC_CONNECTED state (for example, by the gNB sending a RRCResume message). On the other hand, if the buffer status report indicates only a small amount of data in the UE buffer, the gNB may decide to keep the UE in the RRC_INACTIVE state (for example, by the gNB sending a RRCRelease message). Furthermore, the absence of a buffer status report in Msg3 / MsgA may also provide an indication to the gNB that, for example, no more data is available in the UE buffer, resulting in the UE remaining in RRC_INACTIVE. Furthermore, the absence of a buffer status report in Msg3 / MsgA may also provide an indication to the gNB to conclude that, for example, there is no more data available in the UE buffer, so the UE may remain in RRC_INACTIVE.

[0078] As can be seen from the illustration in Fig. 9, the above process, in which the UE must first transition from an INACTIVE state to a CONNECTED state in order to be able to transmit user data in the uplink, introduces latency and consumes significant UE power for each transmission of user data. Furthermore, the signaling overhead incurred for UEs in INACTIVE state when transmitting small data packets is a common problem that gets worse with more UEs being served simultaneously in 5G NR.

[0079] Therefore, 3GPP intends to allow an RRC_Inactive UE to transmit small data in the uplink without changing the UE state to RRC Connected. In general, any device that has intermittent small data packets when in the INACTIVE state can benefit from allowing small data transmission in the INACTIVE state.

[0080] In 3GPP, it has been agreed to enable small data transmission (SDT) using a 4-step RACH, a 2-step RACH (see above, Fig. 6, Fig. 7, etc.) or a configuration grant (CG) procedure (see above, section "Configuration Grant, Grant Free Access, Grant Free Uplink"). Furthermore, the RACH procedure can be specially configured to be used for small data transmission, i.e. a small data specific RACH procedure. However, the normal (legacy) RACH procedure (either 4-step or 2-step) can also be used instead to carry small data, e.g. in Msg3 or MsgA (see Fig. 10 and Fig. 11), i.e. a non-small data specific RACH procedure.

[0081] The UE may be configured to use a small data specific RACH procedure, which may be defined as using different resources than the generic legacy RACH procedure, e.g., the preamble may be different, or the random access opportunity (i.e., in time and / or frequency) may be different.

[0082] For example, both 2-step RACH or 4-step RACH are applicable for RACH-based uplink SDT (small data transmission) in RRC_INACTIVE. For 4-step RACH-based SDT, uplink data is transmitted in Msg3. Based on the received RACH preamble, the gNB identifies that random access is initiated by the UE for small data transmission and allocates an appropriate UL grant size in RAR (Msg2). For 2-step RACH-based SDT, uplink data is transmitted in MsgA. Based on the received RACH preamble, the gNB identifies that RA (random access) is initiated by the UE for small data transmission and allocates an appropriate UL grant size in fallback RAR. Furthermore, based on the received RACH preamble, the gNB identifies an appropriate PUSCH resource to decode. In order for the network to identify that the random access is for small data transmission, the "PRACH opportunity + preamble" combination used for random access initiated for small data transmission may be different from that used for random access initiated for other purposes.

[0083] A small data specific RACH procedure typically has a smaller collision risk than a legacy generic RACH procedure because resources specifically configured for the small data specific RACH are only used for small data transmissions, whereas the regular legacy RACH procedure is used by many more UEs for various reasons. Thus, if a UE is configured to use a small data specific RACH procedure, it will use it for small data transmissions instead of the legacy RACH procedure.

[0084] Depending on the application type of the UE, the UE may have different traffic requirements and correspondingly different packet sizes. The gNB may determine the resources to be assigned to the UE based on a configuration grant (e.g., Type 1). The gNB may perform this determination based on, for example, one or more of subscription information, traffic patterns, and other types of UE assistance information.

[0085] Further example implementations may include, for example, the following details regarding the configuration grant:

[0086] The configuration of the configured grant resources may be provided by the network when the UE is in RRC_CONNECTED, so that the UE can use the configured grant resources when the UE transitions to RRC_INACTIVE. The configuration of the configured resources for the UE's small data transfer is determined by the network in various scenarios, including, for example: UE assistance information provided by the UE indicating traffic patterns Network assessment information including traffic statistics stored by the gNB itself, for example as part of the UE context in case of RRC_INACTIVE UE Request Message: The UE can send a Configuration Grant Request message for future small data transfers when the UE is in RRC_CONNECTED state.

[0087] According to the above-mentioned various cases, the network judges whether to configure the UE with the configured grant resource for small data transmission. The configured grant resource configuration is provided to the UE in the following exemplary scenarios: · When the UE is RRC_CONNECTED, the configuration of the configuration grant resource may be included in the RRC release message with suspendConfig when the UE transitions from RRC_CONNECTED to RRC_INACTIVE based on the UE request message or UE assistance information. In the case of RACH-based small data transmission, the configuration grant resource may be included in the RRC release message contained in MsgB or Msg4 for a user who has succeeded in RACH in response to UE assistance information.

[0088] One possibility to transmit small data in the uplink while the UE is still in RRC_INACTIVE state is to use the RACH procedure as described above.The following assumptions made for Figures 10 and 11 and subsequently for explaining some concepts, solutions and variants of the invention should be considered as merely exemplary.

[0089] Assuming RACH-based small data uplink transmission 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), and simplified exemplary RACH-based small data uplink transmission procedures are shown in Figures 10 and 11. In both Figures 10 and 11, it is exemplarily assumed that the UE is already in RRC_INACTIVE state and has small data available for transmission. Figure 10 assumes a four-step RACH procedure and shows how the UE transmits small data in Msg3. Figure 11 assumes a two-step RACH procedure and shows how the UE transmits small data in MsgA.

[0090] According to an example, the control message and the small data are transmitted together to the base station, for example, together in the same transport block. The UE configures the transport block using resources and multiplexes the 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, for example, in Msg3 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, for example, in MsgA using radio resources selected by the UE from the radio resources previously configured in association with the selected RACH preamble.

[0091] Further, while Fig. 10 and Fig. 11 show that a buffer status report (BSR) can be included in Msg3 and MsgA, respectively, the BSR is shown only in brackets to reflect that the inclusion of the BSR is only an exemplary possibility. For example, in Fig. 10, it is exemplarily assumed that the gNB decides to keep the UE in the RRC_Inactive state, for example because the BSR is not present or indicates that there is only a small amount of uplink small data in the UE buffer. Correspondingly, an RRCRelease message is sent in Msg4. Meanwhile, in Fig. 11, it is exemplarily assumed that the gNB decides to move the UE to the RRC_Connected state, for example because the BSR indicates that there is a significant amount of uplink data in the UE buffer that needs to be transmitted by the UE. Correspondingly, an RRCResume message is sent in MsgA. Furthermore, while Fig. 10 shows the uplink grant separately from the random access response in Msg2, it can be considered that the uplink grant belongs to and is part of the random access response in Fig. 10 equally well.

[0092] In summary, possible exemplary implementations of small data uplink transmission for RRC_INACTIVE UEs are possible and can be based, for example, on such a RACH procedure, whether it is a two-step or a four-step RACH procedure (see Figures 10 and 11). Figures 10 and 11 apply to both small data specific RACH procedures and to normal legacy RACH procedures.

[0093] Fig. 12 illustrates in an exemplary manner configuration grant based small data transmission for two UEs, UE1 and UE2, both in an exemplary inactive state. The radio resources allocated in the periodic CG are illustrated in the top row of Fig. 12 and have a specific period. For example, a heartbeat message may be available for transmission at UE1 every 5 minutes, while the traffic generation of the sensor has a traffic period of every hour.

[0094] The same CG resource is shared between UE1 and UE2 and is available for uplink transmission at UE1 and UE2. Assume that at time t1, small data becomes available for transmission at UE1. The next available CG resource is at time t2, which UE1 uses to perform small data transmission. Similarly, UE1 can use the radio resource allocated by the configuration grant at t4 to transmit the small data generated at t3. Assume exemplarily that at UE2, small data becomes available for transmission at time instance t5, and UE2 transmits the small data using the next available CG opportunity at t6.

[0095] Further improvements As a general and exemplary assumption, transmission by a gNB in ​​5G NR can be performed based on beams, with the SSB being transmitted via a specific beam radiated in a specific direction. Figure 13 shows a simplified exemplary beam sweep transmission by a gNB with two UEs, UE1 and UE2.

[0096] For example, beam sweeping can be achieved by changing the beam direction for each SSB transmission. In other words, there is a one-to-one relationship between the transmission beam (and direction) from the gNB and the SSB. Thus, multiple SSBs are transmitted within a certain time interval, one SSB per beam. Each SSB can be identified by a unique number called the SSB index.

[0097] Multiple UEs are located at different locations and different distances from the gNB. The UE measures the signal strength of each SSB it detects within a certain period of time. From the measurement results, the UE can identify the SSB (and its index) with the strongest signal strength. This SSB with the strongest signal strength is the best beam for the UE.

[0098] One of the developments currently being discussed in 3GPP concerns CG-based small data transmissions, and in particular the use of SSBs to improve them. For example, it was agreed that CG-based small data transmissions require an association between configured grant resources and synchronization signal blocks (SSBs). Furthermore, the associated SSBs must have a signal quality above a threshold, i.e., be sufficiently good, and for example, the RSRP of the SSBs can be used as a parameter reflecting the signal quality. The requirement that only a sufficiently good SSB must be selected by the UE can only be applied to the first CG-based small data transmission, so that the signal quality requirements of the SSBs do not necessarily have to be met for subsequent CG-based small data transmissions. On the other hand, the requirement that only a sufficiently good SSB must be selected by the UE can be applied not only to the first, but also to one or all of the subsequent CG-based small data transmissions.

[0099] One exemplary reason behind the above agreement is that the gNB does not know where the UE is located when it is RRC_Inactive (or RRC_Idle). To help the gNB determine in which direction the UE is located (e.g., which transmission beam the UE is receiving from the gNB), different CG resources can be defined for different SSBs. Then, since the UE uses a CG resource for uplink transmission that is specifically associated with a particular SSB, the gNB can determine the SSB from the CG resource used by the UE, and thus the transmission beam and direction.

[0100] Additionally, the SSBs are used, among other things, to synchronize transmission timing between the UE and the gNB. Requiring the SSBs to have good (e.g., above a threshold) quality increases the reliability of uplink small data transmissions.

[0101] However, if the UE determines that there is no SSB that satisfies the SSB signal quality requirement (e.g., there is no SSB that exceeds the SSB signal quality threshold) as a result of the above agreement, the UE cannot transmit the small data using the configured grant resource, and as a result, the small data may eventually need to be discarded and thus lost.

[0102] Illustratively, as illustratively assumed in FIG. 13, UE1 may determine that SSB2 has the strongest SSB and may use the CG resource associated with the SSB2 beam to transmit available small data, whereas UE2 may detect SSB7 and SSB8, but the signal strength of both SSB7 and SSB8 may be insufficient, so UE2 would not be able to transmit available small data using the configured grant resource.

[0103] The inventors have identified the potential shortcomings and challenges discussed above and have therefore identified the possibility of providing an improved small data transmission procedure that allows for avoiding or mitigating one or more of the problems identified above. The present invention relates to various solutions and variants for such an improved small data transmission procedure.

[0104] <Embodiment> In the following, UEs, base stations, and procedures for meeting these needs are described for new radio access technologies envisioned for 5G mobile communication systems, but may also be used in LTE mobile communication systems. Various implementations and variations are described as well. The following disclosure is facilitated by, and may be based, for example, at least in part on, the discussion and insights discussed above.

[0105] In general, it should be noted that many assumptions have been made herein and will be made below in order to be able to explain the principles underlying the present disclosure in a clear, concise and understandable manner. However, these assumptions should be understood as merely examples made herein for the purpose of explanation and should not limit the scope of the present disclosure. Those skilled in the art will realize that the principles of the following disclosure and claims can be applied in different scenarios and in ways not explicitly described herein.

[0106] Furthermore, some of the terms such as procedures, entities, layers, etc. used below are closely related to those used in the LTE / LTE-A system or current 3GPP 5G standardization, but the specific terms used in the context of new radio access technologies for the upcoming 3GPP 5G communication system have not yet been fully determined or may eventually be changed. Thus, the terms may be changed in the future without affecting the functionality of the embodiments. As a result, those skilled in the art recognize that the embodiments and their scope of protection should not be limited to the specific terms used illustratively in this specification lacking newer terms or terms to be finally agreed upon, but should be more broadly understood by the functions and concepts underlying the functions and principles of the present disclosure.

[0107] For example, a "mobile station" or "mobile node" or "user terminal" or "user equipment (UE)" is a physical entity (physical node) in a communication network. A node may have several functional entities. A functional entity refers to a software or hardware module that implements and / or provides a predefined set of functions to other functional entities of the same or another node or network. A node may have one or more interfaces that attach the node to a communication facility or medium that allows the node to communicate. Similarly, a network entity may have logical interfaces that attach a functional entity to a communication facility or medium that allows the node to communicate with other functional entities or corresponding nodes.

[0108] The term "base station" or "radio base station" in this specification refers to a physical entity in a communication network. Similar to a mobile station, a base station may have several functional entities. A functional entity refers to a software or hardware module that implements and / or provides a predefined set of functions to other functional entities of the same or another node or network. A physical entity performs several control tasks for a communication device, including one or more of scheduling and configuration. Note that the base station functionality and the communication device functionality may be integrated in a single device. For example, a mobile terminal may also implement the base station functionality for other terminals. The term used in LTE is eNB (or eNodeB), while the term currently used for 5G NR is gNB.

[0109] Communications between a UE and a base station are typically standardized and may be defined by different layers, such as PHY, MAC, RRC, etc. (see background discussion above).

[0110] The term "small data" as used in this application should be broadly understood as data that the UE and the base station have agreed upon as small, e.g., as opposed to non-small. For example, whether data is considered small data or not may be defined by the base station by setting a data volume threshold. Alternatively, what constitutes small data may be defined by a telecommunication standard, e.g., by setting a data volume threshold. As an example, a possible definition of what is small data can be found in the corresponding small data section above.

[0111] The term "inactive state" as used in this application should be broadly understood as a state in which normal and large-scale data exchange between the UE and the base station is not possible. A UE in an inactive state (referred to as an "inactive UE") may not have a data connection actively used, but may still have one or more inactive data connections (e.g., existing but not currently used), which allow (small-scale) data transmission without the need to first reactivate the data connection. To complete the explanation, an idle UE does not have a data connection that allows the UE to transmit data to the base station, whereas a connected UE has one or more active data connections that can be immediately used to convey data to the base station.

[0112] The term "periodic radio resources" as used in this application should be broadly understood to refer to radio resources (e.g., time domain and / or frequency domain) that occur periodically in time. These "periodic radio resources" can be assigned to a UE (or UEs) in advance by a corresponding serving base station (serving the UE), so that they are already configured and available for the UE to transmit data without the UE having to first request the radio resources when (small) data becomes available for transmission. In one example, the "periodic radio resources" are of a configuration grant, e.g., a type 1 configuration grant, as described above with respect to a 5G implementation.

[0113] The expression "synchronization signal block" as used in this application should be broadly understood as referring to the transmission of one or more synchronization signals and can be abbreviated as SSB. In one example, this expression refers to a similar or identical SSB to that described above with respect to 5G implementations, including, for example, PSS, SSS, and PBCH. The "signal quality" of a synchronization signal block refers, for example, to the signal quality of one or more synchronization signals in the synchronization signal block. The expression "signal quality exceeding a signal quality threshold" determined by the UE should be understood as determining whether the synchronization signal block has an appropriate quality, for example a sufficiently good quality. For this purpose, a signal quality threshold is defined and each detected synchronization signal block is compared to this threshold. Also, an alternative solution covers the determination of whether the synchronization signal block has a quality equal to or greater than the signal quality threshold.

[0114] The expression "time-triggered control mechanism" as used in this application should be broadly understood as a mechanism for controlling when to trigger a particular action, such as, for example, performing an alternative small data transmission mechanism, but also including an action that still seeks to perform periodic resource-based transmission of small data to avoid alternative transmission of small data.

[0115] The expression "alternative small data transmission mechanism" as used in this application should be broadly understood as a transmission mechanism for transmitting available small data that is an alternative to the originally intended small data transmission mechanism, here periodic resource-based small data transmission, in which pre-configured periodic radio resources are usable by the UE without transmitting a prior scheduling request.

[0116] This application distinguishes between periodic resource based small data transmission (eg, the CG-based SDT mentioned above) and random access based small data transmission (eg, the RA-based SDT mentioned above).

[0117] In the following solution, it is exemplarily assumed that the improved small data transmission procedure is conceptually based on small data transmission already defined according to the 3GPP 4G or 5G standards.

[0118] 14 shows a general, simplified, exemplary block diagram of a user equipment (also referred to as a communication device) and a scheduling device (here exemplarily assumed to be located in a base station such as an eLTE eNB (aka ng-eNB) or a gNB in ​​5G NR). The UE and the eNB / gNB communicate with each other via (wireless) physical channels using their respective transceivers.

[0119] The communication device may include a transceiver and a processing circuit. The transceiver may include a receiver and a transmitter and / or may function as a receiver and a transmitter. The processing circuit may be one or more hardware, such as, for example, one or more processors or any LSI. There is an input / output point (or node) between the transceiver and the processing circuit, through which the processing circuit can control the transceiver during operation, i.e., control the receiver and / or the transmitter to exchange receive / transmit data. The transceiver may include an RF (radio frequency) front, including one or more antennas, amplifiers, and RF modulators / demodulators, as a transmitter and receiver. The processing circuit may perform control tasks, such as, for example, controlling the transceiver to transmit user data and control data provided by the processing circuit and / or to receive user data and control data that are further processed by the processing circuit. In addition, the processing circuit may be responsible for performing other processes, such as, for example, judgment, decision, calculation, measurement, etc. The transmitter may be responsible for performing the process of transmission and other processes related thereto. The receiver may be responsible for performing the process of reception and other processes related thereto, such as monitoring the channel.

[0120] Various solutions of the improved small data transmission procedure are described below. In this connection, an improved UE and an improved base station participating in the improved small data transmission procedure are shown. Corresponding methods of UE operation and base station operation are also provided.

[0121] Figure 15 illustrates a simplified exemplary UE structure according to one exemplary implementation of the improved small data transmission procedure, which may be implemented based on the general UE structure described in relation to Figure 14. The various structural elements of the UE illustrated in this Figure 15 may be interconnected with each other, e.g., by corresponding input / output nodes (not shown), e.g., for exchanging control and user data and other signals. Although not illustrated for purposes of illustration, the UE may include further structural elements.

[0122] As can be seen from FIG. 15, the UE may include a synchronization signal block signal quality judgment circuit, a small data transmission judgment circuit, a time-triggered control mechanism circuit, and a small data transmitter, which may, for example, use periodic radio resources or an alternative small data transmission mechanism, for example, a random access procedure or a cell reselection procedure.

[0123] Thus, in this case, as will become apparent from the disclosure below, the UE receiver may be exemplarily configured to at least partially perform one or more of: receiving configuration information from the base station, such as for configuring periodic resource-based small data transmission or for configuring a time-triggered control mechanism.

[0124] Thus, in this case, as will become apparent from the disclosure below, the processing circuitry of the UE may be exemplarily configured to at least partially perform one or more of: determining that small data is available for transmission using periodic resources; determining a synchronization signal block having a signal quality above a threshold; operating a time-triggered control mechanism; controlling the UE to perform an alternative small data transmission mechanism; operating a timer; operating a counter; determining whether one or more periodic resource opportunities exist during a period of time; etc.

[0125] Thus, in this case, as will become apparent from the disclosure below, the UE transmitter may be illustratively configured to at least partially perform one or more of transmitting small data using periodic resources or as part of a random access procedure.

[0126] One exemplary procedure, disclosed in further more detail below, is implemented by a UE including: A processor of the UE determines that small data has become available for transmission. The available small data is transmitted using periodic resources without a prior scheduling request from the UE. Transmitting the available small data using periodic resources includes the processor determining one of a plurality of synchronization signal blocks having a signal quality that exceeds a signal quality threshold. If the processor determines that no synchronization signal block has a signal quality that exceeds the signal quality threshold, The processor, during operation, operates a time-triggered control mechanism; During operation, the processor controls the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using the periodic resource according to the activated time-triggered control mechanism. Alternative small data transmission mechanisms include: transmitting, by a transmitter of the UE, the available small data using a random access procedure; performing, by the UE, a cell reselection procedure for selecting a new radio cell for transmitting the available small data; Contains one of the following:

[0127] A corresponding exemplary method is executed by a user equipment UE, determining that small data has become available for transmission, the available small data being transmitted using periodic resources without a prior scheduling request from the UE; and transmitting the available small data using the periodic resource includes determining one of a plurality of synchronization signal blocks having a signal quality that exceeds a signal quality threshold. A determining step; If it is determined that there is no synchronization signal block having a signal quality exceeding the signal quality threshold, operating a time-triggered control mechanism; controlling the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using periodic resources according to the activated time-triggered control mechanism; Including, Alternative small data transmission mechanisms include: Using a random access procedure to transmit available small data; performing, by the UE, a cell reselection procedure for selecting a new radio cell for transmitting the available small data; Contains one of the following:

[0128] A sequence diagram corresponding to an exemplary UE operation in line with the UE and UE method discussed above is shown in Figure 16. As can be seen from Figure 16, the UE operation includes a determination as to whether there is a synchronization signal block with a signal quality above a threshold. If yes, this requirement for periodic resource based small data transmission is met and the UE can proceed to transmit small data using the periodic resource associated with that synchronization signal block.

[0129] This may include, for example, the UE determining periodic resources associated with synchronization signal blocks having a signal quality above a threshold, and if there is more than one synchronization signal block with sufficiently good signal quality, the UE may select any one of them, e.g., the one synchronization signal block with the best signal quality. The UE may then use those periodic resources associated with the selected synchronization signal block to transmit small data, e.g., at that particular periodic resource opportunity.

[0130] On the other hand, if there is currently no such synchronization signal block with sufficiently good signal quality, the UE proceeds in another way. Specifically, the UE operates a time-triggered control mechanism to determine whether to transmit the small data using an alternative transmission mechanism, and if so, when to transmit. For example, the time-triggered control mechanism may be operated to allow the UE to perform further attempts to transmit the small data using periodic resources as originally intended, if possible, for a certain period and / or number of times. As is clear from Figure 16, this again includes determining whether there is currently a synchronization signal block with sufficiently good signal quality, and if so, may include periodic resource-based small data transmission.

[0131] Meanwhile, a time-triggered control mechanism is eventually operated to perform an alternative transmission of the small data without using the periodic resources, which may include, for example, transmitting the small data using a random access procedure or performing a cell reselection procedure such that the UE attempts to transmit the small data available in the new radio cell. Thus, the small data transmission can be realized even if the periodic resource-based small data transmission is not possible for some time (e.g., because a sufficiently good synchronization signal block is not found).

[0132] Triggering such an alternative transmission can be implemented in a number of different ways, including a timer, a counter, a combination of a timer and a counter, or a simple one-time initial decision, as described in more detail below (see "First through Fourth Implementations of the Time-Triggered Control Mechanism").

[0133] Thus, the time-triggered control mechanism allows prioritizing the transmission of small data using the originally intended and configured periodic resource by delaying the use of the alternative small data transmission mechanism while still allowing the small data to be transmitted, in other words, the time-triggered control mechanism allows to avoid the alternative small data transmission mechanism to some extent.

[0134] For this purpose, the time-triggered control mechanism may be performed based on a parameter, different values ​​of which result in different delays before using the alternative small data transmission mechanism, during which the UE attempts to perform the originally intended periodic resource-based small data transmission.

[0135] Using an alternative small data transmission mechanism instead of periodic resource-based small data transmission has the advantage that the small data transmission can be performed anyway, which is important in scenarios where the originally intended periodic resource-based small data transmission is not possible at all or is significantly delayed due to, for example, the requirement that periodic resource-based small data transmission is only possible for synchronization signal blocks of sufficiently good quality (e.g. having a signal quality above a signal quality threshold).

[0136] On the other hand, there are several reasons to avoid implementing alternative small data transmission mechanisms, as explained below: Periodic resource-based small data transmission is specially configured by the base station to enable the UE to transmit small data, whereby the configured periodic radio resource can be specifically tailored for small data transmission and possibly dedicated to the UE, e.g., not shared with one or more UEs, and thus the possibility of collision with other UEs is reduced.

[0137] The radio resources of the random access procedure are shared among many UEs and are not necessarily tailored to small data transmission. Although a small data specific random access procedure can be configured in a UE, there is still a possibility of collision with other UEs. In addition, a UE may need to use a non-small data specific random access procedure that is not specific to small data and is used for many purposes (different from small data transmission) by many UEs (e.g., when the UE is not configured to use such a small data specific random access procedure). Thus, the possibility of collision and interference with other UEs is even higher. Failure of small data transmission using such a random access procedure increases signaling overhead and power consumption.

[0138] Overall, the chances of success of small data transmission using random access procedures are typically much lower than periodic resource-based small data transmission.

[0139] Furthermore, performing a cell reselection (and subsequent small data transmission in the new radio cell) also has drawbacks, such as a significant delay before the reselection is completed and a new small data transmission can be attempted, and there is no guarantee that the small data transmission in the new radio cell will be immediately successful. Furthermore, cell reselection also increases power consumption. Thus, cell reselection can also significantly increase signaling overhead and power consumption, which is best avoided if possible.

[0140] The improved small data transmission procedure thus makes it possible to set a trade-off between attempting advantageous periodic resource-based small data transmission, as broadly described above, and as described below according to a number of different implementations and their respective variants, and ensuring that small data is transmitted reliably using other alternative mechanisms, each of which has its own drawbacks.

[0141] Some exemplary implementations of the improved small data transmission procedure also involve a base station to which the UE is currently connected (e.g., referred to as a serving base station). Correspondingly, the improved small data transmission procedure also provides an improved base station participating therein. The base station may include: A transmitter of the base station transmits a configuration message to the user equipment UE to configure the UE to transmit small data that has become available for transmission using periodic resources without prior scheduling request. The transmitter transmits one or more synchronization signal blocks. A processor of the base station determines one or more parameters of a time-triggered control mechanism that is operated by the UE when the UE determines that there is no synchronization signal block having a signal quality exceeding a signal quality threshold, and is operated by the UE to control the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using the periodic resources. The transmitter transmits the one or more parameters to the UE. A receiver of the base station receives the available small data via the periodic resources or via the alternative small data transmission mechanism. The alternative small data transmission mechanism includes one of: transmitting, by the UE, the available small data using a random access procedure; and performing, by the UE, a cell reselection procedure to select a new radio cell from which to transmit the available small data.

[0142] Fig. 17 shows a simplified exemplary base station structure according to one exemplary implementation of the improved small data transmission procedure, which may be implemented based on the general base station structure described in relation to Fig. 14. The various structural elements of the base station shown in this Fig. 17 may be interconnected with each other, for example, by corresponding input / output nodes (not shown), for example, to exchange control and user data and other signals. Although not shown for illustrative purposes, the base station may include further structural elements.

[0143] As can be seen from FIG. 17, the base station comprises a synchronization signal block transmitter, a configuration message transmitter, a determination circuit for determining time-triggered control mechanism parameters, a transmitter for transmitting the time-triggered control mechanism parameters, and a small data receiver capable of receiving small data using periodic radio resources or an alternative small data transmission mechanism, such as a random access procedure.

[0144] The corresponding method is performed by a base station, sending a configuration message to a user equipment (UE) for configuring the UE to transmit small data that has become available for transmission using periodic resources without a prior scheduling request; transmitting one or more synchronization signal blocks; determining one or more parameters of a time-triggered control mechanism operated by the UE when the UE determines that there is no synchronization signal block having a signal quality above a signal quality threshold, for controlling the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using periodic resources; transmitting one or more parameters to the UE; receiving available small data via a periodic resource or via an alternative small data transmission mechanism; Including, Alternative small data transmission mechanisms include: transmitting, by the UE, the available small data using a random access procedure; performing, by the UE, a cell reselection procedure for selecting a new radio cell for transmitting the available small data; Contains one of the following:

[0145] A sequence diagram corresponding to an exemplary base station operation along the lines discussed above is shown in Figure 18. This sequence diagram illustrates an exemplary simplified implementation of the base station method presented above.

[0146] As already discussed above with respect to the UE, the improved small data procedure makes it possible to realize small data transmission even if periodic resource-based small data transmission is not possible for some time (e.g. because the UE cannot find a sufficiently good synchronization signal block). The improved base station makes it possible to optimize the time-triggered control mechanism, in particular to determine the parameters under which the UE operates this mechanism. Thus, the base station can configure the UE exactly how to prioritize the originally intended and configured periodic resource-based small data transmission over alternative small data transmission mechanisms.

[0147] Figure 19 illustrates a simple and exemplary interaction between the improved UE and the improved base station of the improved small data transmission procedure discussed above. In this solution illustrated in Figure 19, it is illustratively assumed that the UE is configured to use periodic resource-based small data transmission, which may include, for example, configuration of periodicity, time / frequency radio resources, etc. Meanwhile, it is illustratively assumed that the base station does not provide configuration information regarding the time-triggered control mechanism. Rather, the UE determines the parameters required to operate the time-triggered control mechanism by itself.

[0148] Figure 19 illustrates in a highly simplified manner that small data becomes available for transmission at the UE and that the UE determines whether any synchronization signal block (SSB) has a quality above a signal quality threshold in the context of transmitting the available small data using the configured periodic resources. If yes, the small data transmission is performed by the UE using the corresponding periodic resource opportunity. On the other hand, if no such SSB is found by the UE, the UE may operate a time-triggered control mechanism and eventually transmit the small data using an alternative small data transmission mechanism, e.g., a random access procedure, after again failing to determine an SSB of sufficiently good quality.

[0149] The above describes an exemplary and general implementation of the improved small data transmission procedure, including the corresponding improved UE and improved base station. In the following, various implementations and variants of the improved small data transmission procedure are shown in detail.

[0150] In one example implementation, the improved small data procedures described above or below may be performed by a UE in an RRC Inactive state, e.g., as described above in connection with the 5G NR standardization, however, in other example implementations, the UE may also be in an RRC_Connected state or an RRC_Idle state.

[0151] In the different implementations of the improved small data transmission procedure described above and below, it is exemplarily assumed that the signal quality of the synchronization signal block is used to determine whether the requirement is met. However, it is also possible to determine the signal quality associated with such a synchronization signal block in a different way. Another possibility is to use instead (or in addition) the signal quality of a reference signal received on the same beam as the synchronization signal block, assuming that the signal quality of the reference signal and the signal quality of the synchronization signal block match. Such a reference signal can be, for example, a Channel Status Information (CSI) reference signal similar or identical to that defined in 5G NR.

[0152] In the different implementations of the improved small data transmission procedure described above and below, the improved small data transmission procedure is described mostly based on a synchronization signal block having a signal quality. According to one exemplary implementation, the synchronization signal block can include one or more synchronization signals, such as a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), and can optionally also include a physical broadcast channel PBCH, for example, the PSS, SSS, and / or PBCH are similar or identical to those defined in 5G NR discussed above. In one exemplary implementation, the signal quality is determined based on one or more synchronization signals of the synchronization signal block. Furthermore, the signal quality can be implemented as, for example, one or more of Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), and Signal to Interference plus Noise Ratio (SINR).

[0153] In the different implementations of the improved small data transmission procedure described above and below, the improved small data transmission procedure may include performing a random access procedure as an alternative small data transmission mechanism. According to an exemplary implementation, the random access procedure may be implemented as a small data specific random access procedure configured by the base station for the UE to use in such a situation. Alternatively, for example, if such a small data specific random access procedure is not configured, the UE may use a non-small data specific random access procedure as an alternative small data transmission mechanism. The difference between the two types of random access procedures may be, for example, one or more of the radio resources and preambles that the UE can use, respectively.

[0154] Additionally or independently, the above-mentioned random access procedure may include two steps, in which case the transmission of the available small data is performed in a first message of a two-step random access procedure, or may include four steps, in which case the transmission of the available small data is performed in a third message of a four-step random access procedure.

[0155] For example, a two-step or four-step RACH procedure similar or identical to that defined for 5G NR discussed above may be used in an example implementation. Corresponding examples of four-step and two-step RACH-based small data transmissions are shown in and described in relation to Figures 10 and 11, respectively.

[0156] Different implementations of the improved small data transmission procedure described above and below include performing cell reselection as an alternative small data transmission mechanism. Thus, cell reselection is performed by the UE to search for a better cell to camp on when none of the current SSBs have a sufficiently good quality.

[0157] For example, cell reselection may include the following steps, etc.

[0158] Step 1. First, the UE scans different radio frequency (RF) channels one by one, which are prioritized based on the information stored in the UE. If a suitable cell is somehow found on any of these RF channels, that cell is selected and the procedure ends. If not, the UE continues with the initial cell selection process described in step 2.

[0159] Step 2. If no preferred RF channel was found in step 1, the UE starts scanning all RF channels in all supported NR bands. On each channel, the UE only needs to search for the strongest cell and verify whether it may be a suitable cell by reading SIB1 and checking the PLMN (Public Land Mobile Network) supported by that cell. If the identified cell is suitable, it is selected and the procedure ends. Otherwise, the UE selects another RF channel to scan and repeats this step.

[0160] According to an example implementation, the cell reselection of the improved small data transmission procedure may be the same as or similar to the cell reselection currently standardized for 5G NR, e.g., as defined in 3GPP TS38.304v16.5.0 section 5.2.

[0161] According to the exemplary implementation of the improved small data transmission procedure described above and below, when the UE uses the cell reselection procedure as an alternative small data transmission mechanism, the timer trigger control can be operated differently such that the cell reselection is triggered immediately, i.e. without introducing a delay (e.g. based on a timer and / or counter), which has the advantage that no additional delay caused by further periodic resource-based small data transmission attempts occurs.

[0162] In a more detailed implementation, the setting of whether cell reselection is triggered immediately or not can be associated with the setting of the periodic resource. In other words, depending on the setting of the periodic resource, the UE triggers cell reselection immediately or operates the time trigger control differently to allow a delay during which the UE can attempt periodic resource-based small data transmission (e.g., using a timer and / or counter). The UE can select any one of the detected SSBs (all of which have poor signal quality) and thus determine the periodic resource associated with the selected SSB. Depending on the periodic resource, the UE has further settings for triggering cell reselection. In one example, the setting of the trigger can depend on the period of the periodic resource. If the period is long (opportunities are sparse), cell reselection can be triggered immediately to avoid a relatively long delay associated with waiting for one or more periodic resource opportunities. On the other hand, if the periodicity is short (opportunity dense), cell reselection may only be triggered after a delay during which the UE may attempt one or more periodic resource-based small data transmissions, which may be introduced, for example, by operating the time-triggered control mechanisms described above and below.

[0163] Additionally or alternatively, the gNB may determine how to configure the UE in the above respect based on the periodicity of the CG resources. For example, the gNB may determine for each SSB when and if cell reselection should be triggered immediately based on the periodicity of the periodic resources associated with that SSB. The gNB then informs the UE of the configuration when and if cell reselection should be triggered immediately, e.g., together with each SSB.

[0164] For example, a parameter exemplarily called CG_SDT_cellreselection may be used in this regard and defined as follows: CG_SDT_cellreselection ::= ENUMERATED (True) (If this is set to false, the UE operates a time-triggered control mechanism, e.g. a timer / counter)

[0165] Similarly, as discussed above, when the periodicity is long (opportunities are sparse), the gNB may configure the UE to trigger cell reselection immediately to avoid the relatively long delay associated with waiting for one or more periodic resource opportunities, whereas when the periodicity is short (opportunities are dense), the gNB may configure the UE to trigger cell reselection only after a delay during which the UE may attempt one or more periodic resource-based small data transmissions.

[0166] In addition to and independently of the above, the small data transmission procedure is further improved when a new radio cell of a new serving base station is selected as a result of cell reselection. This is not always the case, since the UE may reselect a new radio cell of a serving base station with a significantly improved signal quality. The UE provides assistance information to the new serving gNB after cell reselection. For example, the assistance information informs the new serving base station about a preferred CG configuration, and the assistance information includes, for example, information about the traffic pattern at the UE. The new serving base station can take this assistance information into account when configuring the periodic resources of the UE.

[0167] In the cell reselection variants described above and below for the improved small data transmission procedure, it is simply assumed that the UE transmits small data in the new radio cell, and no further details are given. It is assumed that selecting a new cell with better signal quality increases the probability that the UE can successfully transmit small data. According to an exemplary implementation, the UE can use one of different mechanisms for transmitting small data in the new radio cell, such as periodic resource-based small data transmission, RACH-based small data transmission, transmitting small data in RRC connected state, etc.

[0168] Different implementations of the improved small data transmission procedure described above and below include operating a time-triggered control mechanism in the UE, including setting one or more parameters for operating the mechanism. In the following, four different exemplary implementations of such a time-triggered control mechanism according to the improved small data transmission procedure are presented. The first implementation is based on a timer, where upon expiration of the timer, the UE stops attempting periodic resource-based small data transmission and proceeds to transmit small data using the alternative small data transmission mechanism. The second implementation is based on a counter that is incremented each time an attempt of periodic resource-based small data transmission fails, where upon the counter reaches a corresponding counter threshold, the UE stops attempting periodic resource-based small data transmission and proceeds to transmit small data using the alternative small data transmission mechanism. The third implementation is based on a combination of the aforementioned timer and counter, where upon expiration of the timer or upon the counter reaching a counter threshold, whichever occurs first, the UE stops attempting periodic resource-based small data transmission and proceeds to transmit small data using the alternative small data transmission mechanism. A fourth implementation is, for example, based on an early determination in the UE as to whether there is still a possibility to attempt a periodic resource-based small data transmission during a defined period following an initial unsuccessful periodic resource-based small data transmission attempt.

[0169] First implementation of a time-triggered control mechanism - a timer As mentioned above, the first implementation of the time-triggered control mechanism is based on a timer, and when the timer expires, the UE stops attempting periodic resource-based small data transmission and proceeds to transmit the small data using the alternative small data transmission mechanism. Thus, in this case, the timer is used to introduce a maximum delay before the UE can use the alternative transmission mechanism to transmit the small data, regardless of whether the UE actually has further opportunities for periodic resource-based small data transmission while the timer is still running. Thus, the start of the timer can be suitably triggered when the small data becomes available for transmission or later.

[0170] In one exemplary variant, the timer is started the first time the UE determines that there is no synchronization signal block with a signal quality above the signal quality threshold for the transmission of small data available. In other words, the timer is started the first time the UE fails to perform a periodic resource-based transmission of small data using a particular periodic resource opportunity, for example, of an SSB. The UE needs to skip such periodic resource opportunity because the quality of the corresponding synchronization signal block is not good enough.

[0171] In order to be able to identify such periodic resource opportunity that needs to be skipped, the UE first determines one SSB among the detected SSBs (all below the signal quality threshold) and then determines the corresponding periodic resource associated with the one determined SSB. Thus, a first implementation includes, for example, selecting one SSB among all SSBs for operation of the time-triggered control mechanism. According to one example, the UE determines the SSB with the highest signal quality among the SSBs, since it is the one that is most likely to improve the signal quality to exceed the signal quality threshold required for periodic resource-based small data transmission. According to another example, the UE determines the SSB that has the next periodic resource opportunity in time following the generation of the small data. According to another example, the UE can also determine two or more SSBs (even all detected SSBs) as the reference SSB for operation of the time-triggered control mechanism.

[0172] Alternatively, the timer may start at different times, for example, when the small data becomes available for transmission or a certain time after the small data becomes available for transmission. Thus, the first implementation does not require the UE to determine a certain periodic resource opportunity as a criterion for starting the timer (including first determining any SSB among multiple detected SSBs). On the other hand, even if the small data is transmitted as soon as possible using the periodic resource, the timer is started every time the small data becomes available for transmission. Thus, starting such a timer would cause many unnecessary timer starts. From that point of view, it seems advantageous to start the timer when the first periodic resource-based transmission attempt fails, because the timer is started only if there is actually a potential problem that can be solved by using an alternative small data transmission mechanism.

[0173] In an exemplary variant, the timer is stopped upon successful transmission of the small data using the periodic resource.

[0174] While the timer is running, i.e. started but not expired, the UE may proceed to attempt to transmit the available small data using the configured periodic resources. This again involves repeated determination by the UE as to whether a suitable SSB (i.e. one with a sufficiently high signal quality) can be detected. If such a suitable SSB is detected, the UE may proceed to transmit the small data based on the corresponding periodic resources of that suitable SSB. In that case, the timer is stopped. Otherwise, the process is simply repeated until the timer expires.

[0175] FIG. 20 shows a sequence diagram of an exemplary UE operation according to this first implementation of the time-triggered control mechanism described above. Correspondingly, assume that small data becomes available for transmission in due course and the UE proceeds to determine whether there is a synchronization signal block with a signal quality above the signal quality threshold. If yes, the UE can proceed to transmit the small data using the configured periodic resources associated with a suitable SSB. If no, the UE starts a timer and keeps trying to perform a periodic resource-based small data transmission until the timer expires. If the UE finds a suitable SSB at this time, the UE stops the timer and proceeds to transmit the small data using the periodic resources associated with the suitable SSB. Once the timer expires, the UE can resort to an alternative small data transmission mechanism.

[0176] FIG. 21 illustrates an exemplary scenario of small data transmission over time according to this first implementation of the time-triggered control mechanism, particularly when the UE succeeds in transmitting the small data using periodic resources before the timer expires. It is exemplarily assumed that a random access procedure is used as an alternative small data transmission mechanism. Correspondingly, the middle row illustrates random access opportunities that become available to the UE when using this alternative small data transmission mechanism. The bottom row of FIG. 21 illustrates operations at the UE, including the generation of small data at t1. At time t1, the UE may also start determining whether there is a suitable SSB for periodic resource-based transmission of the generated small data. The top row illustrates periodic resource opportunities for one particular SSB, here SSB1, and it is assumed that SSB1 is the SSB selected as the reference for the operation of the timer. Specifically, the timer is started at t2, which corresponds to the first periodic resource opportunity of the reference SSB1, which needs to be skipped by the UE due to the absence of a suitable SSB for periodic resource-based small data transmission.

[0177] As assumed in Fig. 21, the UE succeeds in determining a suitable SSB (one with sufficiently good signal quality) at time t3, which is again exemplarily assumed (for ease of explanation) to be SSB1, which is the one initially selected to operate the time-triggered control mechanism. The UE then transmits small data at time t4 using the next opportunity provided by the periodic resources of SSB1.

[0178] However, an SSB other than SSB1 (ie, the SSB initially selected for the time-triggered control mechanism) may be selected by the UE for small data transmission to sufficiently improve the signal quality.

[0179] Figure 22 illustrates an exemplary scenario of small data transmission over time according to this first implementation of the time-triggered control mechanism, particularly when the UE does not successfully transmit small data using periodic resources before the timer expires and then performs small data transmission using a random access procedure. Similar assumptions as in Figure 21 described above are made in the scenario of Figure 22. We assume that at time t1, small data is generated in the UE, which may also trigger a search for a suitable SSB for periodic resource-based small data transmission. We again assume that the UE selects an SSB, here SSB1, as a reference for operating the time-triggered control mechanism, which includes starting a timer at the first skipped opportunity of the periodic resources of the selected SSB1 (t2 in Figure 22).

[0180] Assume exemplarily that no periodic resource based small data transmission is possible during the time provided by the timer, since no SSB good enough (i.e., above the signal quality threshold) is detected by the UE. Other opportunities for periodic resources, e.g., SSB1, need to be skipped by the UE for the reasons mentioned above (see t3 in FIG. 22). At t4, the timer expires and the UE uses the next RA opportunity at time t5 to transmit small data.

[0181] Thus, the first timer-based implementation of the time-triggered control mechanism provides in a simple manner a configurable time for the UE to attempt further periodic resource-based small data transmissions before allowing the UE to transmit small data using other mechanisms.

[0182] The timer value can be determined in a variety of different ways, some of which are listed below.

[0183] According to a first variant, the UE can determine the timer values ​​autonomously without specific instructions from the gNB. According to one example of these first variants, the UE can determine the timer values ​​based on preconfigured timer information stored in the UE. In this case, the 3GPP standard can define such timer information from which the timer values ​​to be used are derived, in which case the timer information can be part of the UE's operating system. Additionally or alternatively, the mobile network operator can define the timer information and provide it as subscriber information, for example in the SIM card (or e-SIM information) of the UE.

[0184] According to another example of these first variants, the UE can determine the value of the timer based on the period of the periodic resource that the UE may possibly use to transmit the available small data. Since the period of the periodic resource of the SSB is known to the UE from previously obtained information, the UE can also determine the timer value based on the corresponding period when selecting a reference SSB (e.g., SSB1 in Figs. 21 and 22) for the operation of the time-triggered control mechanism.

[0185] For example, the UE determines the timer value as an inverse or multiple of the period. One exemplary concept is to increase the timer value when the period is short, and decrease the timer value when the period is long. Following such a concept, if the periodic resource opportunity is sparse (i.e., the period is long), the timer value can be shortened because there is no point in setting a long timer value since the periodic resource-based small data transmission opportunities are sparse. On the other hand, if the periodic resource opportunity is dense, the timer value can be lengthened to allow the UE to make more attempts to perform the originally intended periodic resource-based small data transmission and to avoid alternative small data transmissions.

[0186] According to a further second variant, the timer value is configured in the UE by the base station. Correspondingly, the UE receives a timer configuration message from the base station, for example via system information or in a UE-dedicated message (for example an RRC message). Correspondingly, the timer configuration message includes appropriate information for the UE to determine the timer value.

[0187] For example, a parameter illustratively called CG_SDT_Timer may be used in this regard and defined as follows: CG_SDT_Timer ::= ENUMERATED { ms10, ms40, ms80, ms100, ms128, ms160, ms256, ms320, ms480, ms512, ms640, ms1024, ms1280, ms2560, ms5120}

[0188] The timer value can be determined by the gNB specifically for the UE, in the sense that the timer value can be different for different UEs. Correspondingly, the gNB determines different timer values ​​for different UEs and sends corresponding timer configuration messages containing different timer information to the different UEs. The gNB can take UE-specific information, such as the service of the UE, into account when determining the timer value.

[0189] The second variant in which the base station determines the timer value may have the advantage that the base station has more knowledge about the “best”, e.g. most appropriate, timer value to be used by the UE, since the base station may take into account various other parameters when determining the timer value, e.g. traffic patterns, traffic characteristics of the UE and other UEs, interference situation in the radio cell, and QoS requirements, etc.

[0190] In addition to, but independently of, the first and second variants above on how the UE can determine the timer value autonomously or using a configuration from the gNB, the timer value can depend on the specific circumstances, e.g. the logical channel associated with the available small data or, as alluded to above, the particular periodic resource used for small data transmission.

[0191] More specifically, it is generally assumed that the small data from one or more logical channels configured in the UE can be generated. Thus, the small data available for transmission can be associated with one or more logical channels. The logical channels can differ with respect to their characteristics, for example, the traffic requirements of the logical channels, the Quality of Service (QoS) requirements of the logical channels, or the priority of the logical channels. The value of the timer used for the time-triggered control mechanism can depend on the one or more logical channels associated with the small data. For this purpose, the UE has information associating different logical channels or characteristics of the logical channels with corresponding timer values. The UE then determines the one or more logical channels with which the available small data is associated and derives the timer value corresponding to the logical channel or its characteristics from the stored association information. If the available small data is associated with multiple logical channels, in one example, the UE determines the smallest timer value among the timer values ​​associated with the multiple logical channels.

[0192] In other examples, different periodic resources (e.g., different periods) can be associated with different timer values. This solution has already been described in relation to how a UE can autonomously determine a timer value, for example based on an inverse or multiple of a period of a periodic resource.

[0193] Second implementation of the time-triggered control mechanism - Counter As mentioned above, the second implementation of the time-triggered control mechanism is based on a counter that is incremented each time an attempt at periodic resource based small data transmission fails, and when the counter reaches a corresponding counter threshold, the UE stops attempting periodic resource based small data transmission and proceeds to transmit the small data using the alternative small data transmission mechanism.

[0194] In one exemplary variant of the second implementation, a counter is incremented each time the processor fails to use a particular periodic resource location because it could not find a suitable synchronization signal block (i.e., one with a sufficiently good signal quality). Thus, in this case, the counter is used to minimize the number of additional attempts of periodic resource-based small data transmission before allowing the UE to use an alternative small data transmission mechanism to transmit the available small data. This is different compared to the timer-based first implementation of the time-triggered control mechanism, which operates somewhat independently of whether the UE is actually given at least one further opportunity to perform periodic resource-based small data transmission.

[0195] In order to be able to identify such missed periodic resource opportunities, corresponding to the first implementation of the time-triggered control mechanism described above, the UE first determines one SSB among the detected SSBs (all below the signal quality threshold) and then determines the corresponding periodic resource associated with the one determined SSB. Thus, the second implementation includes, for example, such a step of selecting one SSB among all SSBs for the operation of the time-triggered control mechanism. According to one example, the UE determines the SSB with the highest signal quality among the multiple SSBs, since it is the one that is most likely to be able to improve the signal quality to exceed the signal quality threshold required for periodic resource-based small data transmission. According to another example, the UE determines the SSB that has the next periodic resource opportunity in time following the generation of the small data. According to another example, the UE can also determine two or more SSBs (even all detected SSBs) as the reference SSB for the operation of the time-triggered control mechanism.

[0196] In an exemplary variant, the counter is reset upon successful transmission of the small amount of data using the periodic resource.

[0197] During the period when the counter has not yet reached its counter threshold, the UE may proceed to attempt to transmit the available small data using the configured periodic resources. This again involves repeated determination by the UE as to whether a suitable SSB (i.e., one with sufficiently high signal quality) can be detected. If such a suitable SSB is detected, the UE may proceed to transmit the small data based on the suitable SSB's corresponding periodic resource. In that case, the counter is reset. Otherwise, the counter is incremented with each failed attempt, and the process is repeated with each further periodic resource opportunity.

[0198] FIG. 23 shows a sequence diagram of an exemplary UE operation according to this second implementation of the time-triggered control mechanism described above. Correspondingly, assume that small data becomes available for transmission in due course and the UE proceeds to determine whether there is a synchronization signal block with a signal quality above the signal quality threshold. If yes, the UE can proceed to transmit the small data using the configured periodic resource associated with the appropriate SSB. If no, the UE starts a counter operation and increments the counter by one for the skipped periodic resource-based small data transmission opportunity. The UE continues to attempt to perform periodic resource-based small data transmission until the counter reaches the corresponding counter threshold. If the UE finds a suitable SSB this time, the UE resets the counter and proceeds to transmit the small data using the periodic resource associated with the suitable SSB. When the counter reaches the threshold, the UE can resort to an alternative small data transmission mechanism.

[0199] FIG. 24 illustrates an exemplary scenario of small data transmission over time according to this second implementation of the time-triggered control mechanism, particularly when the UE succeeds in transmitting small data using periodic resources before the counter reaches the counter threshold. As in FIG. 21 and FIG. 22, assume exemplarily that a random access procedure is used as an alternative small data transmission mechanism. Assume that a counter threshold 2 is configured in the UE, i.e., the UE attempts to transmit available small data using the initially configured periodic resources twice before the use of the alternative small data transmission mechanism is allowed. At time t1, the UE can generate small data and also start determining whether there is a suitable SSB for periodic resource-based transmission of the generated small data. The top row of FIG. 24 illustrates periodic resource opportunities for one particular SSB, here SSB1, and assume that SSB1 is the SSB selected as the basis for the operation of the counter.

[0200] At time t2, the UE has the first periodic resource opportunity for reference SSB1, which needs to be skipped by the UE due to the lack of a suitable SSB for periodic resource-based small data transmission. Correspondingly, the counter is incremented by 1 and thus has the value 1.

[0201] Further assume that the UE succeeds in determining a suitable SSB at time t3, which is again exemplarily assumed to be SSB1 (for ease of explanation), which is the one initially selected for operating the time-triggered control mechanism. The UE then transmits small data at time t4 using the next opportunity provided by the periodic resource of SSB1. However, an SSB other than SSB1 (i.e., the SSB initially selected for the time-triggered control mechanism) may be selected by the UE for transmitting small data using its periodic resource to sufficiently improve the signal quality.

[0202] Figure 25 illustrates an exemplary scenario of small data transmission over time according to this second implementation of the time-triggered control mechanism, particularly when the UE does not successfully transmit small data using periodic resources before the counter reaches a counter threshold and then performs small data transmission using a random access procedure. Similar assumptions as in Figure 24 described above are made in the scenario of Figure 25. At time t1, it is assumed that small data is generated in the UE, which may also trigger a search for a suitable SSB for periodic resource-based small data transmission. Again, it is assumed that the UE selects an SSB, here SSB1, as a reference for operating the time-triggered control mechanism, which includes incrementing the counter at the first skipped opportunity of the periodic resources of the selected SSB1 (t2 in Figure 25).

[0203] It is exemplarily assumed that no periodic resource-based small data transmission is possible during the number of attempts provided by the counter, since no sufficiently good (i.e., above the signal quality threshold) SSB is detected by the UE. Specifically, the next periodic resource opportunity at t3 needs to be skipped by the UE for the same reason, which results in a further increment of the counter. Correspondingly, the counter reaches a value of 2, thus reaching the configured counter threshold. Correspondingly, the UE transmits small data using the next RA opportunity at time t4.

[0204] Thus, the second counter-based implementation of the time-triggered control mechanism ensures that the UE has at least a minimum number of attempts to perform periodic resource-based small data transmissions, which is not guaranteed by the first timer-based implementation of the time-triggered control mechanism. On the other hand, if the period of the selected reference SSB is very long, the delay introduced by this counter mechanism may be large, which is avoided by providing an upper time limit when using the timer described in the first implementation.

[0205] Similar to the timer value, the counter threshold value can be determined in various different ways. In order to avoid repetition, reference is made to the corresponding description on how to determine the timer value. In brief, according to a first variant, the UE can determine the counter threshold autonomously without specific instructions from the base station, for example, from pre-configured counter information stored in the UE, or based on the period of the periodic resource that the UE uses to transmit the available small data (for example, the inverse or multiple of the period).

[0206] Furthermore, according to a second variant, a specific counter threshold is configured in the UE by the base station, for example using a counter threshold configuration message from the base station.

[0207] For example, a parameter illustratively referred to as CG_SDT_Counter_threshold may be used in this regard and defined as follows: CG_SDT_Counter_threshold ::= Integer (0..65535)

[0208] Furthermore, the base station can determine the value of the counter threshold according to the same principles disclosed above for determining the timer value, taking into account other parameters, e.g., traffic patterns, traffic characteristics of the UE and other UEs, and other UE-specific information, UE-specific counters, etc.

[0209] In addition to, but independently of, the first and second variants described above regarding how the UE can determine the counter threshold value autonomously or using a configuration from the gNB, the value of the counter threshold value can depend on the specific circumstances, e.g. the logical channel associated with the available small data or the specific periodic resource used for transmitting the small data, etc. Again, reference is made to the specific detailed explanations given in the above point in relation to the timer values, e.g. the logical channel dependent counter threshold value, the periodic resource dependent counter threshold value and the UE specific counter threshold value.

[0210] A third implementation of the time-triggered control mechanism - a combination of a timer and a counter As mentioned above, the third implementation of the time-triggered control mechanism is based on a combination of the timer and counter mentioned above, where the UE stops attempting periodic resource-based small data transmission when the timer expires or when the counter reaches a counter threshold, whichever occurs first, and proceeds to transmit small data using the alternative small data transmission mechanism. Alternatively, the use of the alternative small data transmission mechanism is triggered only if both mechanisms are triggered. In other words, the third implementation is a combination of the first and second implementations of the time-triggered control mechanism, allowing to benefit from the advantages of both implementations. Specifically, the use of both mechanisms of time-triggered control allows setting an upper time limit (i.e., timer) or an upper number of attempts (i.e., counter) to trigger the alternative small data transmission mechanism based on the mechanism that triggered earlier. Another advantage is that if the periodicity of the CG resource is sparse, it may take a long time for the UE to reach the counter threshold. Such a problem can be solved by relying on the timer.

[0211] The operation of the timer according to this third embodiment can be the same as that described in detail above for the first implementation. Similarly, the operation of the counter according to this third implementation can be the same as that described in detail above for the second implementation. And, the timer and the counter are operated in parallel as described above.

[0212] Figure 26 shows a sequence diagram of an exemplary UE operation according to this third implementation of the time-triggered control mechanism described above. In this exemplary implementation of Figure 26, the timer expiry is checked first, and then the counter threshold is checked. However, other implementations are possible as well, such as one in which the counter threshold is checked first and then the timer expiry, or one in which the two checks are performed in parallel.

[0213] Furthermore, the operation of the timer and counter mechanisms may be adapted to have a corresponding effect on the other mechanism, for example resetting a counter when a timer expires or stopping a timer when a counter reaches a threshold.

[0214] Otherwise, the UE behavior of the third implementation is a direct combination of the first and second implementations, including the initiation of the timer and the first increment of the counter occurring after the first failed periodic resource-based small data transmission (see "Is there a synchronization signal block with a signal quality above the threshold" in Figure 26). If the timer has not expired and the counter has not reached the counter threshold, a repeated attempt of the periodic resource-based small data transmission is allowed. If either condition becomes true, the UE may proceed to transmit the small data using an alternative small data transmission mechanism (here, exemplarily, a random access procedure).

[0215] Fourth implementation of the time-triggered control mechanism - determining the period As mentioned above, the fourth implementation of the time-triggered control mechanism is based on an early determination in the UE as to whether there is still a possibility to attempt further periodic resource-based small data transmissions during a defined period following a first failed periodic resource-based small data transmission (e.g., the first time it is determined that there is no SSB good enough for small data transmission). Thus, the fourth implementation allows a very early determination in a simple manner as to whether it is really worth delaying an alternative small data transmission. For example, if there are no more periodic resource opportunities during that period, the UE has practically no or only a small chance to even attempt further periodic resource-based small data transmissions. In such a case, the UE can decide to use the alternative small data transmission mechanism to transmit small data at the next opportunity (e.g., the next RA opportunity, see FIG. 28) after the negative determination.

[0216] On the other hand, if the UE determines that there are one or more periodic resource opportunities for transmitting small data available during the period, the UE may delay using the alternative small data transmission mechanism until it has exhausted attempts to transmit small data using those remaining periodic resource opportunities during the period. The UE may then successfully transmit the small data on one of those remaining periodic resource opportunities, which may include determining that at least one of the SSBs has improved to have a signal quality above a threshold.

[0217] Alternatively, if the UE fails to transmit small data in any one of those remaining periodic resource opportunities (because the UE could not find a suitable SSB), the UE may transmit the available small data using an alternative small data transmission mechanism after the last of those remaining periodic resource opportunities. The alternative small data transmission may be performed, for example, at the next opportunity after the skipped periodic resource opportunity at the end of the period or at the next opportunity after the expiration of the period.

[0218] In one exemplary variant, the time period starts from the first failed periodic resource-based transmission attempt on the first periodic resource opportunity of the SSB, or the time period can start at another time, for example the first time that small data is generated.

[0219] This determination may also be made by comparing the period of the periodic resource to the length of the period: if the period is longer than the period, there are no further periodic resource opportunities; if the period is shorter than the period, there must be at least one further periodic resource opportunity.

[0220] In order to be able to identify such missed periodic resource opportunities, corresponding to the first, second and third implementations of the time-triggered control mechanism described above, the UE first determines one SSB from among the detected SSBs (all below the signal quality threshold) and then determines the corresponding periodic resource associated with the one determined SSB. Thus, the fourth implementation may also include such a step of selecting one SSB from among all SSBs for the operation of the time-triggered control mechanism, for example. According to one example, the UE determines the SSB with the highest signal quality from among the multiple SSBs, since it is the one that is most likely to be able to improve the signal quality to exceed the signal quality threshold required for the periodic resource-based small data transmission. According to another example, the UE determines the SSB that has the next periodic resource opportunity in time following the generation of the small data. According to another example, the UE may also determine two or more SSBs (even all detected SSBs) as the reference SSB for the operation of the time-triggered control mechanism. However, in the latter case, as the number of reference SSBs increases, the likelihood that no periodic resource opportunities will exist during the period decreases, and therefore the likelihood of immediate use of the alternative small data transmission mechanism also decreases.

[0221] FIG. 27 shows a sequence diagram of an exemplary UE operation according to this fourth implementation of the time-triggered control mechanism described above. As is evident from FIG. 27, the sequence step of the UE operation executed when the UE does not find a suitable SSB for the first time when attempting to transmit available small data is "start the period if not started". This sequence step should be understood in combination with the subsequent check of "are there any further periodic resource opportunities in the period?". Thus, specifically, the UE continuously attempts to transmit small data on all periodic resource opportunities in the period until the UE finds a suitable SSB and transmits the small data using the periodic resources associated with that SSB, or until there are no further periodic resource opportunities SSB in the initially determined period. If the UE determines that there are no more remaining periodic resource opportunities in the period, the UE can trigger an alternative small data transmission mechanism to transmit the small data pending transmission.

[0222] Figure 28 illustrates an exemplary scenario of small data transmission over time according to this fourth implementation of the time-triggered control mechanism, particularly when the UE determines that there are no further configuration grant opportunities during the following period. Again, it is exemplarily assumed that a random access procedure is used as an alternative small data transmission mechanism, and correspondingly, the middle row of Figure 28 illustrates random access opportunities. It is further exemplarily assumed that small data becomes available for transmission in due course (see time t1) and the UE proceeds to start determining whether there is an SSB with a signal quality above the signal quality threshold. The top row of Figure 28 illustrates periodic resource opportunities for one particular SSB, here SSB1, which is exemplarily assumed to be the SSB selected as the basis for operating the period-based time-triggered control mechanism of the fourth implementation.

[0223] At time t2, the UE has a first possibility to transmit small data using a periodic resource opportunity of reference SSB1, which must be skipped by the UE because neither SSB1 nor the other detected SSBs have sufficient quality for periodic resource-based small data transmission. Thus, at time t2, the UE determines a period and then determines whether or not one or more periodic resource opportunities of SSB1 exist during that period. Since this is not the case in the example scenario of FIG. 28, the UE proceeds to transmit the pending small data at the next random access opportunity at time t3.

[0224] FIG. 29 illustrates an exemplary scenario of small data transmission over time according to this fourth implementation of the time-triggered control mechanism, particularly when the UE determines that there is a further configuration grant opportunity during the subsequent period, but the UE still fails to perform a periodic resource-based small data transmission. The assumptions are essentially the same as in FIG. 28 discussed above. Meanwhile, the period used by the UE at time t2 is significantly longer than the exemplary scenario illustrated in FIG. 28, so that the periodic resource opportunity at time t3 falls within that period. For the above reasons, the UE does not immediately perform an alternative small data transmission. Instead, the UE continues to attempt to transmit small data using the periodic resources of any suitable SSB (not only the reference SSB1), and thus continues to check whether there is an SSB with a signal quality that exceeds the signal quality threshold. Assuming that no suitable SSB is found, the UE needs to skip the periodic resource opportunity of SSB1 at t3, and as a result, decides to transmit small data using the first random access opportunity at time t4 (the first RA opportunity after the end of the period).

[0225] Although not shown in Figure 29, an alternative solution involves using the first random access opportunity after time t3 to transmit the small data using a random access procedure. This first random access opportunity can be after, but even during, the last periodic resource opportunity of SSB1. Such a solution has the potential advantage of not incurring any further delay before using the alternative small data transmission mechanism.

[0226] FIG. 30 illustrates an exemplary scenario of small data transmission over time according to this fourth implementation of the time-triggered control mechanism, particularly when the UE determines that there is a further configuration grant opportunity during the subsequent period and the UE can perform periodic resource-based small data transmission at that opportunity. According to this scenario, after the UE fails to transmit small data using the periodic resource opportunity of the reference SSB1 at time t2, the UE can still perform periodic resource-based small data transmission at time t4 because the signal quality of the SSB1 has improved beyond the required signal quality threshold (see time t3). Although the above scenario assumes that the reference SSB1 has improved and is selected, any SSB other than the reference SSB1 may improve and be selected by the UE for small data transmission using the periodic resource of that SSB.

[0227] The period can be determined in various different ways similar or identical to the timer value in the first and third implementations and the counter threshold value in the second and third implementations, and reference is made to the corresponding description sections regarding how to determine the timer value and the counter threshold value.

[0228] Specifically, according to the first variant, the UE can determine the period autonomously without specific instructions from the gNB. According to one example of these first variants, the UE can determine the length of the period based on pre-configured period information stored in the UE. In this case, the 3GPP standard can define such period information from which the period length to be used is derived, in which case the period information can be part of the UE's operating system. Additionally or alternatively, the mobile network operator can define the period information and provide it as subscriber information, for example in the SIM card (or e-SIM information) of the UE.

[0229] According to another example of these first variants, the UE can determine the length of the period based on the period of the periodic resource that the UE uses to transmit the available small data. Since the period of the periodic resource of the SSB is known to the UE from previously obtained information, the UE can also determine the length of the period based on the corresponding period when selecting an SSB for the operation of the time-triggered control mechanism.

[0230] For example, the UE determines the period length as an inverse or multiple of the period. One exemplary concept is to increase the period length when the period is short, and vice versa, to decrease the period length when the period is long. Following such a concept, when the periodic resource opportunity is sparse (i.e., the period is long), the period length can be decreased because the opportunities for periodic resource-based small data transmission are sparse, so that it is meaningless to allow many transmission attempts. On the other hand, when the periodic resource opportunity is dense, the period length can be increased to allow the UE to make more attempts to perform the originally intended periodic resource-based small data transmission, and to avoid alternative small data transmissions.

[0231] According to a further second variant, the period length is set by the base station to the UE. Correspondingly, the UE receives a period setting message from the base station, for example via system information or in a UE-dedicated message (for example an RRC message). Correspondingly, the period setting message includes appropriate information for the UE to determine the period length.

[0232] For example, a parameter illustratively called CG_SDT_Timer may be used in the above regard and defined as follows: CG_SDT_Timer ::= ENUMERATED { ms10, ms40, ms80, ms100, ms128, ms160, ms256, ms320, ms480, ms512, ms640, ms1024, ms1280, ms2560, ms5120}

[0233] The period length can be determined specifically for the UE by the gNB, in the sense that the period length can be different for different UEs. Correspondingly, the gNB determines different period lengths for different UEs and sends corresponding period setting messages including different period lengths to the different UEs.

[0234] The second variant in which the base station determines the period length may have the advantage that the base station has more knowledge about the “best”, e.g. most appropriate, period length to be used by the UE, since it may take into account various other parameters, e.g. traffic patterns, traffic characteristics of the UE and other UEs, interference situation in the radio cell, and QoS requirements, etc.

[0235] In addition to, but independently of, the first and second variants above on how the UE can determine the period length autonomously or using a configuration from the gNB, the period length can depend on the particular circumstances, such as, for example, the logical channel associated with the available small data or, as alluded to above, the particular periodic resource used for small data transmission.

[0236] More specifically, it is generally assumed that the small-scale data from one or more logical channels configured in the UE can be generated. Thus, the small-scale data available for transmission can be associated with one or more logical channels. The logical channels can differ with respect to their characteristics, for example, the traffic requirements of the logical channels, the Quality of Service (QoS) requirements of the logical channels, or the priority of the logical channels. The length of the period used for the time-triggered control mechanism can depend on the one or more logical channels associated with the small-scale data. For this purpose, the UE has information associating different logical channels or characteristics of the logical channels with corresponding period lengths. The UE then determines the one or more logical channels with which the available small-scale data is associated and derives the period length from the stored association information. If the available small-scale data is associated with multiple logical channels, in one example, the UE determines the minimum period length among the period lengths associated with the multiple logical channels.

[0237] In other examples, different periodic resources (e.g., different periods) can be associated with different period lengths. This solution has already been described in relation to how a UE can autonomously determine the period length, for example based on an inverse or multiple of a period of the periodic resource.

[0238] In the above disclosure, four different exemplary implementations of a time-triggered control mechanism operating in a UE have been described.

[0239] Independently of the above, further implementations of the improved small data transmission procedure will focus on improving how the UE satisfies the requirement that the SSB for periodic resource-based small data transmission must have a sufficiently good signal quality. In other implementations of the improved small data transmission procedure, it has been assumed that the UE compares the quality of each detected SSB with a single signal quality threshold. In other words, it has been exemplarily assumed that a single signal quality threshold is commonly used to compare with all SSBs.

[0240] However, a further advantageous implementation of the improved small data transmission procedure does not require the use of only a single threshold, thereby allowing the use of multiple signal quality thresholds comparable to SSB.

[0241] Specifically, this implementation of the improved small data transmission procedure further includes determining a signal quality threshold, e.g., from among multiple signal quality thresholds available to the UE. For example, the signal quality threshold can be different between different SSBs detected by the UE, e.g., depending on the periodic resource of each SSB. As a result, the signal quality threshold can be different for each SSB, such that the UE compares the signal quality of each detected SSB with an SSB-specific signal quality threshold.

[0242] Such an implementation has the advantage that selection of an appropriate SSB for small data transmission over each different SSB is made easier (e.g., lowering the signal quality threshold) or more difficult (e.g., raising the signal quality threshold), as needed.

[0243] According to a first variant, the determination of the signal quality threshold takes into account one or more transmission parameters usable by the UE for the transmission of small data via the SSB. For example, the transmission parameters may include one or more of a transport block size, a modulation scheme, and a coding rate defined in relation to the periodic resources of the SSB. The transmission parameters used by the UE for the small data transmission may be different for each detected SSB and are known to the UE in the same way as the periodic resources associated with the detected SSB.

[0244] For example, the UE may have stored association information that associates a particular signal quality threshold with one or more of the transmission parameters. Correspondingly, when the UE checks a particular signal quality of an SSB, the UE first determines one or more associated transmission parameters associated with the SSB and used to transmit small data via the SSB. Then, the UE derives an associated signal quality threshold based on the determined one or more transmission parameters and the stored association. Then, the signal quality of the SSB is compared with the signal quality threshold so derived.

[0245] An exemplary underlying principle of the first variant of the method in which the signal quality threshold can vary depending on one or more transmission parameters is given below. The underlying principle is that the signal quality threshold should be adapted to the transmission parameters in order to increase the likelihood of successful transmission of small data. For example, the signal quality threshold can have a high value associated with one or more of a large transport block size and a high modulation scheme. Thus, when a transmission parameter that generally benefits from high channel quality is used (e.g., 16QAM or 64QAM instead of QPSK), this implementation should use a relatively high signal quality threshold, which results in a higher channel quality for the selected SSB and a higher likelihood of successful small data transmission.

[0246] Conversely, the signal quality threshold may have a low value associated with one or more of a small transport block size and a low modulation scheme. Thus, when transmission parameters that do not necessarily require high channel quality are used (e.g., BPSK or QPSK instead of 16QAM or 64QAM), this implementation allows for a relatively low signal quality threshold. As a result, the UE is also allowed to use SSBs with relatively low signal quality, because the relatively robust transmission parameters (e.g., modulation scheme, coding rate) are used, so that the small data transmission is still likely to be successful.

[0247] Thus, one advantage of the first variant may be that small data transmissions using periodic resources are more likely to be successful, since the selection of the SSB is tailored to the small data transmission itself, e.g., to the transmission parameters used by the UE to transmit the small data over the respective SSB. For example, the UE may be able to select an SSB with relatively poor signal quality (in the case of robust transmission parameters), which the UE may not otherwise be able to select due to commonly used signal quality thresholds.

[0248] According to a second variant, the determination of the signal quality threshold takes into account a priority associated with the periodic resources of the SSB used by the UE for the transmission of small data. More specifically, the periodic resources configured for the SSB may also be associated with a priority reflecting, for example, a reliability requirement for the periodic resources configured by the gNB.

[0249] Thus, the priority of the periodic resources of each SSB is known to the UE in the same way as the periodic resources themselves.

[0250] For example, the UE may have stored association information that associates a particular signal quality threshold with a priority. Correspondingly, when the UE checks a particular signal quality of an SSB, the UE first determines a priority associated with the SSB. The UE then derives an associated signal quality threshold based on the determined priority and the stored association. The signal quality of the SSB is then compared with the signal quality threshold so derived.

[0251] An exemplary underlying principle of the second variant of how the signal quality threshold can be different depending on the priority is as follows: For example, the higher the priority of the periodic resource, the higher the signal quality threshold, so as to ensure that the transmission of small data is more reliable according to the reliability requirement reflected by the priority. Conversely, the lower the priority of the periodic resource, the lower the signal quality threshold.

[0252] The above implementations and variations thereof present a solution in which different signal quality thresholds can be used instead of a single common signal quality threshold for all SSBs. Independently of the above, the SSB thresholds can be determined autonomously by the UE without necessarily having threshold setting information from the gNB, or can be determined by the UE based on threshold setting information provided by the gNB.

[0253] The various SSB thresholds may be determined by the gNB and then signaled to the UE, for example together with the configuration of different periodic resources. Thus, for example, the SSB-specific configuration of periodic resources by the gNB also includes the configuration of SSB-specific signal quality thresholds.

[0254] For example, a dedicated parameter can be used in the above respect and defined as follows: CG_SDT_RSRP_threshold_range ::= INTEGER (0..127), or CG_SDT_RSRQ_threshold_range ::= INTEGER (0..127)

[0255] The gNB may determine each signal quality threshold as described above, for example taking into account one or more of the transmission parameters of the periodic resources specific to each SSB or the priority of the periodic resources.

[0256] In other solutions, the UE may autonomously determine SSB-specific signal quality thresholds without specific configuration of the signal quality thresholds from the gNB. In relation to the above, the UE determines for each SSB signal quality check the appropriate signal quality threshold according to one of the above variants, for example taking into account one or more of the transmission parameters of the periodic resource or the priority of the periodic resource. Since this information is known to the UE, no dedicated configuration information from the gNB is required.

[0257] Fig. 31 shows a sequence diagram of an exemplary UE operation according to this advantageous implementation of the improved small data transmission procedure. Fig. 31 is exemplarily based on the general improved small data transmission procedure described in relation to Fig. 16. Compared to the general solution of Fig. 16, this implementation further comprises a sequence step of determining an SSB and determining a signal quality threshold corresponding to said SSB, and further adapts a subsequent SSB check, checking whether said SSB has a sufficiently good quality, to be performed against this specially determined signal quality threshold.

[0258] Although the differences compared to Figure 16 are described only in relation to Figure 31, the differences specific to this implementation may also be applied to other implementations of the improved small data procedures, for example the UE operations illustrated and described in the UE sequence diagrams of Figures 20, 23, 26 and 27.

[0259] In the above description of this implementation, the use of several signal quality thresholds has been described as being used in addition to the improved small data transmission procedure described above which operates a time-triggered control mechanism to trigger the use of alternative small data transmission mechanisms in an appropriate manner.

[0260] However, the use of some signal quality thresholds according to the implementation described above can also be provided in a stand-alone manner, independent of the timer-triggered control mechanism and the alternative small data transmission mechanism. For example, the UE determines that small data is available for transmission using periodic resources. As required for periodic resource-based transmission, the UE determines one of a number of synchronization signal blocks that has a signal quality exceeding the signal quality threshold. More specifically, this is done based on any of the variants of this implementation described above, including, for example, determining a suitable signal quality threshold (e.g., from among a number of thresholds) and then comparing the signal quality of each SSB with the signal quality threshold determined by the UE specifically for that purpose.

[0261] Then, if a suitable SSB having a signal quality exceeding the specially determined signal quality threshold is detected by the UE, the UE determines a periodic resource associated with the determined synchronization signal block, and transmits the available small data using the determined periodic resource. On the other hand, if a suitable SSB is not detected by the UE, the UE cannot transmit data and continues to search for a suitable SSB for transmitting the available small data.

[0262] In the following, another implementation of the improved small data transmission procedure is described. This improved small data transmission procedure is independent of the above implementations, but can also be combined with any of the above. Specifically, this implementation provides an additional trigger for using the random access-based small data transmission procedure even when the UE is configured to perform the periodic resource-based small data transmission procedure.

[0263] The UE may determine whether the available small data to transmit exceeds a data volume threshold, which may be set, for example, by the gNB. In one example, this additional determination may be performed by the UE when the UE fails to transmit small data using periodic resources due to a lack of a suitable SSB (one with sufficiently good signal quality). If the amount of small data then exceeds the data volume threshold, the UE may discontinue periodic resource-based small data transmission and transmit the small data using a random access procedure instead.

[0264] On the other hand, if the UE determines that the amount of small data is below the data amount threshold, the UE may proceed with the originally intended periodic resource-based small data transmission according to any of the implementations described above (e.g., using one of the first to fourth implementations of time-triggered control).

[0265] Further Aspects According to a first aspect, there is provided a user equipment including: a processor of the UE determines that small data has become available for transmission, the available small data being transmitted using a periodic resource without a prior scheduling request from the UE, and transmitting the available small data using the periodic resource includes the processor determining one of a plurality of synchronization signal blocks having a signal quality that exceeds a signal quality threshold, if the processor determines that no synchronization signal block has a signal quality that exceeds the signal quality threshold; The processor, during operation, operates a time-triggered control mechanism; During operation, the processor controls the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using the periodic resource according to the activated time-triggered control mechanism. Alternative small data transmission mechanisms include: transmitting, by a transmitter of the UE, the available small data using a random access procedure; performing, by the UE, a cell reselection procedure for selecting a new radio cell for transmitting the available small data; Contains one of the following:

[0266] According to a second aspect provided in addition to the first aspect, the time-triggered control mechanism is controlled to attempt to avoid execution of the alternative small data transmission mechanism according to the parameter. In an optional implementation, the time-triggered control mechanism is operated by the processor according to the parameter to enable transmission of the available small data using the periodic resource, including the processor determining, during operation, one of a plurality of synchronization signal blocks having a signal quality exceeding a signal quality threshold for periodic resource-based transmission of the available small data.

[0267] According to a third aspect provided in addition to the first or second aspect, a processor executes a time-triggered control mechanism based on a timer. In an optional implementation, the timer includes: starting a timer when the processor determines for the first time that no synchronization signal block having a signal quality exceeding a signal quality threshold is available for transmission of small data; While a started timer has not yet expired, - attempting to transmit available small data using periodic resources, each of which includes a processor determining one of a plurality of synchronization signal blocks having a signal quality above a signal quality threshold; - stopping the started timer when the UE successfully transmits the available small data using the periodic resource at the periodic resource opportunity; When the timer expires, the processor controls the UE to perform an alternative small data transmission mechanism; The device may be operated according to one or more of the following:

[0268] According to a fourth aspect provided in addition to the third aspect, the processor, during operation, sets a value of a timer to: pre-configured timer information indicating a value of one of the timers, optionally the pre-configured timer information being stored in the UE as part of an operating system of the UE or as part of subscriber information; a timer setting message, the UE including a receiver for receiving, in operation, a timer setting message from a serving base station, optionally the timer setting message being received from system information or being a message dedicated to the UE; a period of a periodic resource used to transmit the available small data, the processor determining, during operation, a value of a timer as a multiple of the period or an inverse of the multiple, and optionally, during operation, the processor determining a larger value of the timer for shorter periods of the periodic resource and a smaller value of the timer for longer periods of the periodic resource; one of at least one logical channel associated with the small data, wherein the processor, during operation, determines from the stored timer information a value associated with the logical channel as a timer value, and optionally, the processor determines a minimum value of a plurality of values ​​associated with the plurality of logical channels associated with the small data as a timer value, and optionally, the timer value is determined based on one or more of a traffic requirement, a quality of service requirement, and a priority of the logical channel; Based on one or more of: The timer value is UE specific.

[0269] According to a fifth aspect provided in addition to the first or second aspect, the processor executes a time-triggered control mechanism based on a counter that counts the number of times the processor determines that there is no synchronization signal block having a signal quality above a signal quality threshold for the transmission of available small data. In an optional implementation, the counter includes: Incrementing a counter each time the processor determines that there is no synchronization signal block having a signal quality above a signal quality threshold for the transmission of small data available for a periodic resource opportunity; While the counter has not reached the counter threshold, - attempting to transmit available small data using periodic resources, each of which includes a processor determining one of a plurality of synchronous signal blocks having a signal quality above a signal quality threshold; - stopping the counter when the UE successfully transmits the available small data using the periodic resource in the periodic resource opportunity; When the counter reaches a counter threshold, the processor controls the UE to perform an alternative small data transmission mechanism; The device may be operated according to one or more of the following:

[0270] According to a sixth aspect provided in addition to the fifth aspect, the processor, during operation, determines a value of the counter threshold by: pre-configured counter information indicating one value of a counter threshold, optionally the pre-configured counter information being stored in the UE as part of an operating system of the UE or as part of subscriber information; a counter setting message, the UE including a receiver for receiving, during operation, a counter setting message from a serving base station, optionally the counter setting message being received from system information or being a message dedicated to the UE; a period of a periodic resource used to transmit the available small data, the processor determining, during operation, a value of the counter threshold as a multiple or an inverse of the multiple of the period, and optionally, the processor determining, during operation, a larger value of the counter threshold for a shorter period of the periodic resource and a smaller value of the counter threshold for a longer period of the periodic resource; one of at least one logical channel associated with the small data, wherein the processor, during operation, determines from the stored counter information a value associated with the logical channel as a counter threshold value, and optionally, the processor determines a minimum value of a plurality of values ​​associated with the plurality of logical channels associated with the small data as the counter threshold value, and optionally, the counter threshold value is determined based on one or more of a traffic requirement, a quality of service requirement, and a priority of the logical channel; Based on one or more of: The value of the counter threshold is UE specific.

[0271] According to a seventh aspect, provided in addition to the third and fifth aspects, the processor executes a time-triggered control mechanism based on a combination of a timer and a counter, and the processor controls the UE to execute an alternative small data transmission mechanism when the counter reaches a counter threshold or when the timer expires, whichever occurs first.

[0272] According to an eighth aspect provided in addition to the first or second aspect, the processor executes the time-triggered control mechanism based on whether one or more periodic resource opportunities exist during a period following a determination that there is no synchronization signal block having a signal quality above a signal quality threshold for transmitting available small data. In an optional implementation, if there are no more periodic resource opportunities during the subsequent period, the processor controls the UE to execute an alternative small data transmission mechanism at a next opportunity following the determination that there is no periodic resource opportunity. If there are one or more periodic resource opportunities during the subsequent period, the processor successively attempts to transmit available small data using the periodic resource at each of one or more subsequent periodic resource opportunities during a subsequent time period, each of which includes determining one of the plurality of synchronization signal blocks having a signal quality that exceeds a signal quality threshold; If the UE determines that there is no synchronization signal block having a signal quality exceeding the signal quality threshold for each of one or more subsequent periodic resource opportunities, the processor controls the UE to perform an alternative small data transmission mechanism at the opportunity following the last periodic resource opportunity in the subsequent period or at the opportunity following the expiration of the subsequent period.

[0273] According to a ninth aspect provided in addition to the eighth aspect, the one or more periodic resource opportunities during the subsequent time period include: one of several synchronization signal blocks, or The synchronization signal block having the highest signal quality among multiple synchronization signal blocks, or - Two or more of multiple synchronization signal blocks is associated with.

[0274] According to a tenth aspect provided in addition to the eighth or ninth aspect, during operation, a processor determines a value of the period of time as: preset time period information indicating one value of the time period, optionally the preset time period information being stored in the UE as part of the UE's operating system or as part of the subscriber information; a period setting message, the UE including a receiver for receiving, during operation, the period setting message from a serving base station, optionally the period setting message being received from system information or being a message dedicated to the UE; a period of a periodic resource used to transmit the available small data, the processor determining during operation a value of the period as a multiple or an inverse of a multiple of the period, and optionally the processor determining during operation a larger value of the period for a shorter period of the periodic resource and a smaller value of the period for a longer period of the periodic resource; one of at least one logical channel associated with the small data, wherein the processor, during operation, determines from the stored duration information a value associated with the logical channel as a duration value, and optionally, the processor determines a minimum value of a plurality of values ​​associated with the plurality of logical channels associated with the small data as a duration value, and optionally, the duration value is determined based on one or more of a traffic requirement, a quality of service requirement, and a priority of the logical channel; Based on one or more of: The duration value is UE specific.

[0275] According to an eleventh aspect provided in addition to any one of the first to tenth aspects, the processor, in operation, determines a signal quality threshold from among a plurality of signal quality thresholds, one or more of the plurality of signal quality thresholds being specific to one or more different transmission parameters usable by the UE for transmission of the small data, including one or more of different transport block sizes, different modulation schemes, and different coding rates, and the processor, in operation, determines a signal quality threshold from the plurality of signal quality thresholds as a signal quality threshold associated with the one or more transmission parameters used by the UE for transmission of the available small data. In an optional implementation, at least some of the plurality of signal quality thresholds are defined based on a higher value of the signal quality threshold being associated with one or more of a larger transport block size and a higher modulation scheme. Furthermore, in an optional implementation, at least some of the plurality of signal quality thresholds are defined based on a lower value of the signal quality threshold being associated with one or more of a smaller transport block size and a lower modulation scheme.

[0276] According to a twelfth aspect provided in addition to any one of the first to tenth aspects, a processor, during operation, determines a signal quality threshold from among a plurality of signal quality thresholds, one or more of the plurality of signal quality thresholds being specific to different priorities associated with periodic resources usable by the UE for transmission of small data, and the processor, during operation, determines a signal quality threshold from among the plurality of signal quality thresholds as a signal quality threshold associated with a priority of the periodic resource associated with the respective synchronization signal block. In an optional implementation, at least some of the plurality of signal quality thresholds are defined based on a higher value of the signal quality threshold being associated with a higher priority of the periodic resource. In a further optional implementation, at least some of the plurality of signal quality thresholds are defined based on a lower value of the signal quality threshold being associated with a lower priority of the periodic resource.

[0277] According to a thirteenth aspect provided in addition to the first aspect, when the UE is configured to perform cell reselection as an alternative small data transmission mechanism, the processor is configured to operate a time-triggered control mechanism such that cell reselection is performed immediately without delay after determining that there is no synchronization signal block having a signal quality above a signal quality threshold. Additionally or alternatively, the transmitter, during operation, when connected to the new radio cell, transmits information regarding a preferred configuration of the periodic resources to a serving base station of the new radio cell. Additionally or alternatively, the transmitter, during operation, transmits the small data in the new radio cell.

[0278] According to a fourteenth aspect provided in addition to any one of the first to thirteenth aspects, if the processor succeeds in determining a synchronization signal block having a signal quality above a signal quality threshold, The processor, during operation, determines a periodic resource associated with the determined synchronization signal block; During operation, the transmitter transmits available small data using the determined periodic resource.

[0279] According to a fifteenth aspect provided in addition to any one of the first to fourteenth aspects, the UE is in an inactive state of a connected state, an idle state, and an inactive state. Additionally or alternatively, instead of using a signal quality of the synchronization signal block, a signal quality of a reference signal received via the same beam as the synchronization signal block is used. Additionally or alternatively, the synchronization signal block includes one or more synchronization signals including a primary synchronization signal PSS and a secondary synchronization signal SSS, and optionally includes a physical broadcast channel PBCH, and optionally the signal quality is determined based on one or more of the synchronization signals of the synchronization signal block. Additionally or alternatively, the random access procedure is a small-scale data specific random access procedure or a non-small-scale data specific random access procedure, and optionally the non-small-scale data specific random access procedure is used when the UE is not configured to use the small-scale data specific random access procedure, and optionally one or more of the radio resources and preambles available for the non-small-scale data specific random access procedure and the small-scale data specific random access procedure are different from each other. Additionally or alternatively, the small-scale data specific random access procedure and the non-small-scale data specific random access procedure include two steps or four steps, and the transmission of the available small-scale data is performed in a first message of the two-step random access procedure or a third message of the four-step random access procedure. Additionally or alternatively, the signal quality is one or more of a reference signal received power RSRP, a reference signal received quality RSRQ, and a signal-to-interference-and-noise ratio SINR.

[0280] According to a sixteenth aspect, a method, executed by a user equipment (UE), comprising: determining that small data has become available for transmission, the available small data being transmitted using periodic resources without a prior scheduling request from the UE; and transmitting the available small data using the periodic resource includes determining one of the plurality of synchronization signal blocks having a signal quality that exceeds a signal quality threshold. A determining step; If it is determined that there is no synchronization signal block having a signal quality exceeding the signal quality threshold, operating a time-triggered control mechanism; controlling the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using periodic resources according to the activated time-triggered control mechanism; Including, Alternative small data transmission mechanisms include: Using a random access procedure to transmit available small data; performing, by the UE, a cell reselection procedure for selecting a new radio cell for transmitting the available small data; A method is provided that includes one of:

[0281] According to a seventeenth aspect, there is provided a base station comprising: a transmitter of the base station transmits a configuration message to a user equipment UE for configuring the UE to transmit small data that has become available for transmission using periodic resources without a prior scheduling request; the transmitter transmits one or more synchronization signal blocks; a processor determines one or more parameters of a time-triggered control mechanism that is operated by the UE when the UE determines that there is no synchronization signal block having a signal quality above a signal quality threshold, and that is operated by the UE to control the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using the periodic resources; the transmitter transmits the one or more parameters to the UE; a receiver receives the available small data via the periodic resources or via the alternative small data transmission mechanism; the alternative small data transmission mechanism includes: transmitting, by the UE, the available small data using a random access procedure; performing, by the UE, a cell reselection procedure for selecting a new radio cell for transmitting the available small data; Contains one of the following:

[0282] According to an 18th aspect provided in addition to the 17th aspect, a parameter of the time-triggered control mechanism is a timer value, and the time-triggered control mechanism is operated by the UE based on the timer such that upon expiry of the timer at the timer value the UE executes an alternative small data transmission mechanism. A transmitter sends a timer setting message to the UE for setting a timer value of the timer in the UE, optionally the timer setting message being sent via system information or as a UE-specific message. A processor determines the timer value based on a period of the periodic resource. The processor determines a timer value specific to the UE.

[0283] According to a 19th aspect provided in addition to the 17th or 18th aspects, a parameter of the time-triggered control mechanism is a value of a counter threshold, and the time-triggered control mechanism is operated by the UE based on the counter such that when the counter reaches the counter threshold, the UE executes an alternative small data transmission mechanism. A transmitter sends a counter setting message to the UE for setting the value of the counter threshold in the UE, optionally the counter setting message is sent via system information or as a UE-specific message. A processor determines the counter threshold based on a period of the periodic resource. A processor determines a UE-specific counter threshold.

[0284] According to a twentieth aspect provided in addition to the seventeenth aspect, a parameter of the time-triggered control mechanism is a period value, and the time-triggered control mechanism is operated by the UE based on whether or not one or more periodic resource opportunities are present during a period following a determination by the UE that there is no synchronization signal block having a signal quality above a signal quality threshold, and if there is no periodic resource opportunity during the following period, the UE executes an alternative small data transmission mechanism at the next opportunity following the determination that there is no periodic resource opportunity. The transmitter sends a period setting message to the UE for setting the period value in the UE, and optionally a counter setting message is sent via system information or as a UE-dedicated message.

[0285] According to a twenty-first aspect provided in addition to any one of the seventeenth to twentieth aspects, a processor determines a plurality of signal quality thresholds, where one or more of the plurality of signal quality thresholds are specific to one or more different transmission parameters usable by the UE for transmitting the small data, including one or more of different transport block sizes, different modulation schemes, and different coding rates, or where one or more of the plurality of signal quality thresholds are specific to different priorities associated with periodic resources usable by the UE for transmitting the small data. The transmitter transmits a signal quality threshold setting message to the UE for setting the plurality of signal quality thresholds to the UE.

[0286] According to a twenty-second aspect, a method for transmitting a signal to a base station, the method comprising: sending a configuration message to a user equipment (UE) for configuring the UE to transmit small data that has become available for transmission using periodic resources without a prior scheduling request; transmitting one or more synchronization signal blocks; determining one or more parameters of a time-triggered control mechanism operated by the UE when the UE determines that there is no synchronization signal block having a signal quality above a signal quality threshold, for controlling the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using periodic resources; transmitting one or more parameters to the UE; receiving available small data via a periodic resource or via an alternative small data transmission mechanism; Including, Alternative small data transmission mechanisms include: transmitting, by the UE, the available small data using a random access procedure; performing, by the UE, a cell reselection procedure for selecting a new radio cell for transmitting the available small data; A method is provided that includes one of:

[0287] According to a twenty-third aspect, there is provided an integrated circuit for controlling processing of a user equipment, in operation, the processing being performed by the user equipment, determining that small data has become available for transmission, the available small data being transmitted using periodic resources without a prior scheduling request from the UE; and transmitting the available small data using the periodic resource includes determining one of the plurality of synchronization signal blocks having a signal quality that exceeds a signal quality threshold. A determining step; If it is determined that there is no synchronization signal block having a signal quality exceeding the signal quality threshold, operating a time-triggered control mechanism; controlling the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using periodic resources according to the activated time-triggered control mechanism; Including, Alternative small data transmission mechanisms include: Using a random access procedure to transmit available small data; performing, by the UE, a cell reselection procedure for selecting a new radio cell for transmitting the available small data; An integrated circuit is provided that includes one of the following:

[0288] According to a twenty-fourth aspect, there is provided an integrated circuit for controlling processing of a base station, in operation, the processing being performed by the base station, sending a configuration message to a user equipment (UE) for configuring the UE to transmit small data that has become available for transmission using periodic resources without a prior scheduling request; transmitting one or more synchronization signal blocks; determining one or more parameters of a time-triggered control mechanism operated by the UE when the UE determines that there is no synchronization signal block having a signal quality above a signal quality threshold, for controlling the UE to perform an alternative small data transmission mechanism instead of transmitting the available small data using periodic resources; transmitting one or more parameters to the UE; receiving available small data via a periodic resource or via an alternative small data transmission mechanism; Including, Alternative small data transmission mechanisms include: transmitting, by the UE, the available small data using a random access procedure; performing, by the UE, a cell reselection procedure for selecting a new radio cell for transmitting the available small data; An integrated circuit is provided that includes one of the following:

[0289] Further variations, including hardware and software implementations of the present disclosure The present disclosure can be realized by software, hardware, or software interlocked with hardware. Each functional block used in the description of each embodiment above can be partially or entirely realized by an LSI such as an integrated circuit, and each process described in each embodiment can be partially or entirely controlled by the same LSI or a combination of LSIs. The LSI may be formed as an individual chip, or a single chip may be formed to include some or all of the functional blocks. The LSI may include data input / output coupled thereto. Here, the LSI may be called an IC (integrated circuit), a system LSI, a super LSI, or an ultra LSI depending on the degree of integration. However, the technology for realizing the integrated circuit is not limited to the LSI, and may be realized using a dedicated circuit, a general-purpose processor, or a processor for a specific application. Furthermore, an FPGA (Field Programmable Gate Array) that can be programmed after the manufacture of an LSI or a reconfigurable processor that can reconfigure the connection and settings of the circuit cells arranged inside the LSI may be used. The present disclosure can be realized as digital processing or analog processing. If future integrated circuit technologies replace LSI as a result of advances in semiconductor technology and other derived technologies, the functional blocks can be integrated using the future integrated circuit technologies. Biotechnology can also be applied.

[0290] The present disclosure may be implemented by any type of apparatus, device or system having communication capabilities, referred to as a communications apparatus.

[0291] A communication device may include a transceiver and processing / control circuitry. The transceiver may include and / or function as a receiver and a transmitter. The transceiver as a transmitter and receiver may include a Radio Frequency (RF) module including amplifiers, RF modulators / demodulators, etc., and one or more antennas.

[0292] Some non-limiting examples of such communications devices include telephones (e.g., mobile (cell) phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, netbooks), 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, digital book readers, telehealth / telemedicine (remote health and remote medical) devices, and vehicles (e.g., automobiles, airplanes, ships) that provide communications capabilities, and various combinations thereof.

[0293] The communications apparatus is not limited to being portable or mobile, but may include any type of apparatus, device or system that is non-portable or fixed, such as smart home devices (e.g., appliances, lighting, smart meters, control panels), vending machines, and any other "thing" in an "Internet of Things (IoT)" network.

[0294] Communications may include, for example, exchanging data via cellular systems, wireless LAN systems, satellite systems, and the like, as well as various combinations thereof.

[0295] A communications apparatus 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 apparatus 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 apparatus.

[0296] Additionally, the communications equipment may include infrastructure facilities such as, for example, base stations, access points, and any other equipment, devices, or systems that communicate with or control equipment such as those in the non-limiting examples above.

[0297] (Control signal) In this disclosure, the downlink control signal (information) related to this 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) or RRC of a higher layer. The downlink control signal may be a predefined signal (information).

[0298] The uplink control signal (information) related 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 or RRC of a higher layer. Also, the uplink control signal may be a predefined signal (information). The uplink control signal may be replaced by uplink control information (UCI), first stage sidelink control information (SCI), or second stage SCI.

[0299] (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. Also, in sidelink communication, a terminal may be employed instead of the base station. The base station may be a relay device that relays communication between an upper node and a terminal. The base station may be a roadside unit.

[0300] (uplink / downlink / sidelink) The present disclosure may be applied to any of the uplink, downlink, and sidelink.

[0301] The present disclosure may apply, for example, to uplink channels such as PUSCH, PUCCH, and PRACH, downlink channels such as PDSCH, PDCCH, and PBCH, and sidelink channels such as the Physical Sidelink Shared Channel (PSSCH), the Physical Sidelink Control Channel (PSCCH), and the Physical Sidelink Broadcast Channel (PSBCH).

[0302] 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.

[0303] (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.

[0304] (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, in some cases, 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).

[0305] (Time Interval) In the present disclosure, the time resource unit is not limited to one or a combination of a slot and a symbol, and may be a time resource unit such as a frame, a superframe, a subframe, a slot, a time slot subslot, a minislot, or a time resource unit such as 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 any number of symbols exemplified in the above embodiment(s), and may be other numbers of symbols.

[0306] (Frequency Band) The present disclosure may be applied to both licensed and unlicensed bands.

[0307] (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 vehicle to everything (V2X) communication. The channels in the present disclosure may be replaced with PSCCH, PSSCH, physical sidelink feedback channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, and PBCH.

[0308] The present disclosure may also be applied to any of terrestrial networks and non-terrestrial networks (NTN: Non-Terrestrial Networks) using satellites or High Altitude Pseudo Satellites (HAPS). The present disclosure may also be applied to networks with large cell sizes and terrestrial networks with large delays compared to the symbol length or slot length, such as ultra-wideband transmission networks.

[0309] (Antenna port) An antenna port refers to a logical antenna (antenna group) formed by one or more physical antennas (multiple possible). That is, an antenna port does not necessarily refer to one physical antenna, but may refer to an array antenna formed by multiple antennas. For example, the number of physical antennas forming an antenna port is not defined, and instead, an antenna port is defined as the smallest unit by which a terminal can transmit a reference signal. Also, an antenna port may be defined as the smallest unit for multiplying the weighting of a precoding vector.

[0310] Furthermore, the various embodiments may be implemented by means of software modules which are executed by a processor or directly in hardware. A combination of software modules and hardware implementations may also be possible. The software modules may be stored in any kind of computer-readable storage medium, for example RAM, EPROM, EEPROM, flash memory, registers, hard disks, CD-ROM, DVD, etc. Furthermore, it should be noted that individual features of the different embodiments may be the subject of another embodiment, either individually or in any combination.

[0311] Those skilled in the art will recognize that numerous changes and / or modifications may be made to the present disclosure as shown in the specific embodiments, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

Claim 1 A communication device, during operation, a processor that determines to transmit small-scale data using a configured grant resource without transitioning to a connected state, wherein the configured grant resource is associated with at least one synchronization signal block having a signal quality exceeding a signal quality threshold, when the processor determines that there is no synchronization signal block having the signal quality exceeding the signal quality threshold, the communication device transmits the small-scale data using a random access procedure. Communication device. Claim 2 When the processor determines that there is no synchronization signal block having the signal quality exceeding the signal quality threshold, the communication device operates a timer, when the timer is not running, the communication device transmits the small-scale data using the random access procedure. The communication device according to claim 1. Claim 3 The timer, when it is determined to transmit the small-scale data, starts the timer, while the started timer has not expired, the processor attempts to transmit the small-scale data using the configured grant resource, when the timer expires, when the processor determines to transmit the small-scale data using the random access procedure, the timer is stopped, is operated according to one or more of the above. The communication device according to claim 2. Claim 4 The timer is set through a radio resource control (RRC) message. The communication device according to claim 2. Claim 5 The communication device transmits the small-scale data using the configured grant resource based on a counter, when the counter reaches the counter threshold, the communication device determines that the transmission of the small-scale data has failed. The communication device according to claim 1. Claim 6 The communication device receives a configuration of a type 1 configured grant for the configured grant resource through an RRC message. The communication device according to claim 1. Claim 7 The random access procedure is a contention-based random access procedure. The communication device according to claim 1. Claim 8 The processor determines the signal quality threshold from among a plurality of signal quality thresholds during operation. The communication device according to claim 1. Claim 9 When the communication device performs cell reselection after a trial of transmitting the small-scale data using the configured grant resource, the communication device determines that the transmission of the small-scale data using the configured grant resource has failed. The communication device according to claim 1.

10. When the processor succeeds in determining a synchronization signal block having the signal quality exceeding the signal quality threshold, During operation, the processor determines a configured grant resource associated with the determined synchronization signal block, During operation, the transmitter transmits the small-scale data using the determined configured grant resource. The communication device according to claim 1.

11. The communication device is in the inactive state among a connected state, an idle state, and the inactive state. The communication device according to claim 1.

12. The synchronization signal block includes one or more synchronization signals including a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), and optionally includes a physical broadcast channel (PBCH), and the signal quality is determined based on one or more signals among the synchronization signals of the synchronization signal block. The communication device according to claim 1.

13. The random access procedure is a first random access procedure or a second random access procedure, the first random access procedure is specific to the small-scale data, and the second random access procedure is not specific to the transmission of the small-scale data. The second random access procedure is used when the first random access procedure is not configured for the communication device, and one or more radio resources and preambles for the first random access procedure are different from one or more radio resources and preambles for the second random access procedure. The communication device according to claim 1.

14. The signal quality is a reference signal received power (RSRP). The communication device according to claim 1.

15. Performed by a communication device, Determining to transmit small-scale data using a configured grant resource without transitioning to a connected state, including the step of, The configured grant resource is associated with at least one synchronization signal block having a signal quality exceeding a signal quality threshold. When it is determined that there is no synchronization signal block having the signal quality exceeding the signal quality threshold value, transmitting the small-scale data using a random access procedure; including a method.

16. A transmitter that transmits to the communication device a configuration message for configuring the communication device to transmit small-scale data using a configured grant resource without a transition to a connected state during operation; A processor that determines that the small-scale data is to be transmitted using a random access procedure by the communication device when the communication device determines that there is no synchronization signal block having a signal quality exceeding a signal quality threshold value during operation; A receiver that receives the small-scale data using the configured grant resource or the random access procedure during operation; comprising a base station.

17. When the communication device determines that there is no synchronization signal block having a signal quality exceeding a signal quality threshold value, a timer is operated by the communication device, When the timer is not running, the communication device transmits the small-scale data using the random access procedure. The base station according to claim 16.

18. Performed by a base station, transmitting to the communication device a configuration message for configuring the communication device to transmit small-scale data using a configured grant resource without a transition to a connected state; determining that the small-scale data is to be transmitted using a random access procedure by the communication device when the communication device determines that there is no synchronization signal block having a signal quality exceeding a signal quality threshold value; receiving the small-scale data using the configured grant resource or the random access procedure; including a method.

19. An integrated circuit that controls the processing of a communication device during operation, the processing including: a process of determining to transmit small-scale data using a configured grant resource without a transition to a connected state; the configured grant resource is associated with at least one synchronization signal block having a signal quality exceeding a signal quality threshold value; a process of transmitting the small-scale data using a random access procedure when it is determined that there is no synchronization signal block having the signal quality exceeding the signal quality threshold value; including an integrated circuit.

20. An integrated circuit that controls the processing of a base station during operation, the processing comprising: transmitting, without a transition to a connected state, a configuration message to the communication device for configuring the communication device to transmit small-scale data using configured grant resources; determining that the small-scale data is to be transmitted by the communication device using a random access procedure when the communication device determines that there is no synchronization signal block having a signal quality exceeding a signal quality threshold; receiving the small-scale data using the configured grant resources or the random access procedure; including; an integrated circuit.

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