Communication device and communication method for resource allocation of multi-physical random access channel transmission

Abstract

This disclosure provides a communication device and a communication method for resource allocation of multi-physical random access channel (multi-PRACH) transmissions. The communication device includes a circuit that, during operation, determines a group of ROs (Random Access Channel Occasions) containing one or more random access channel occasions (ROs) based on the number of PRACH transmissions in multiple physical random access channel (PRACH) transmissions, and determines a preamble to be used for the ROs based on a mapping between one or more preambles and one or more RO groups, and a transmission unit that transmits the preambles during operation.

Description

Technical Field

[0001] The present disclosure relates to a communication device and a communication method. In particular, it relates to a communication device and a communication method for resource allocation of multi-physical random access channel (multi-PRACH) transmission.

Background Art

[0002] In new radio (NR), it has been confirmed that the physical random access channel (PRACH) is a bottleneck channel from the viewpoint of coverage performance. Therefore, in Release 18 of the technical specification (TS) of the related 3rd Generation Partnership Project (3GPP (registered trademark)), for example, RP-213579, a new work item (WI) regarding coverage enhancement (CovEnh) of new radio (NR) has been approved, and its purpose is to define PRACH coverage enhancement under the physical layer working groups RAN1 and RAN2 of 3GPP. In this WI, multiple PRACH transmissions using the same beam in the 4-step random access channel (RACH) procedure are further considered, and if justified, PRACH transmissions using different beams in the 4-step RACH procedure are considered and defined.

[0003] In Technical Specifications (TS) Releases 15, 16, and 17, the PRACH preamble resource is divided to distinguish between multiple functions for different purposes, such as preambles for contention-free random access (CFRA), 2-step RACH, 4-step RACH, and combinations of functions (including reduced capability (RedCap), small data transmission, slice grouping, and repeated transmission requests for message 3). Furthermore, in multi-PRACH transmissions, separate preambles are required depending on the number of PRACH transmissions, such as 2, 4, and 8 PRACH transmissions. Multi-PRACH transmissions can also be referred to as multiple PRACH transmissions, numerous PRACH transmissions, or a single PRACH attempt.

[0004] However, the technical specifications for releases 15 / 16 / 17 do not specify how PRACH preamble resources for multi-PRACH transmissions are implemented. If separate preambles are used for multiple values ​​of the number of PRACH transmissions using the existing PRACH preamble partitioning described above, the preamble resources will not be fully utilized, and there may be a shortage of preambles available for other purposes, resulting in reduced efficiency of preamble resource utilization.

[0005] Furthermore, the SSB-RO (synchronization signal block to RACH occasion) mapping currently defined in TS is primarily designed for single PRACH transmissions and may not function adequately for multi-PRACH transmissions. For example, if an RO group consists of shared ROs and the SSB-RO association period is set short, user equipment (UE) may not be able to determine enough shared ROs for a large number of PRACH transmissions. Consequently, the UE may only be able to transmit a small number of PRACHs, and the base station (gNB) may not be able to achieve the desired combined gain for preamble detection. Shared RO means that an RO is shared between a single PRACH transmission and a multi-PRACH transmission.

[0006] Therefore, there is a need to provide a communication device and communication method for resource allocation of multi-PRACH transmission that solves the above problems. [Overview of the Initiative]

[0007] Non-limiting and exemplary embodiments contribute to providing communication devices and communication methods for resource allocation of multi-PRACH transmissions.

[0008] According to a first embodiment of the present disclosure, a communication device is provided which, during operation, determines a group of ROs including one or more random access channel occasions (ROs) based on the number of PRACH transmissions in multiple physical random access channel (PRACH) transmissions, and determines a preamble to be used for the ROs based on a mapping between one or more preambles and one or more RO groups, and a transmitting unit that transmits the preambles during operation.

[0009] According to a second embodiment of the present disclosure, a base station is provided which, in operation, determines a mapping between one or more preambles and one or more groups of random access channel occasions (ROs) based on an index associated with one or more multiple physical random access channel (PRACH) transmissions, and a transmitter unit, in operation, signals the mapping to a communication device.

[0010] A third embodiment of the present disclosure provides a communication method which determines a group of random access channel occasions (ROs) based on the number of PRACH transmissions in multiple physical random access channel (PRACH) transmissions, determines a preamble to be used for the ROs based on a mapping between one or more preambles and one or more RO groups, and transmits the preambles in the ROs.

[0011] It should be noted that general or specific embodiments can be implemented as systems, methods, integrated circuits, computer programs, storage media, or any selective combination thereof.

[0012] Further advantages and effects of one embodiment of this disclosure will be made apparent from the specification and drawings. Such advantages and / or effects are provided by several embodiments and features described in the specification and drawings, but not all of them are necessarily provided in order to obtain one or more identical features. [Brief explanation of the drawing]

[0013] The embodiments described herein are merely examples, but will be better understood and readily apparent to those skilled in the art through the following description and in conjunction with the drawings. [Figure 1] This diagram shows an example architecture of a 3GPP NR Radio Access Network (NR-RAN) to which exemplary embodiments of this disclosure apply. [Figure 2] Schematic diagram illustrating the functional partitioning between an NG-RAN and a 5G Core Network (5GC) to which exemplary embodiments of this disclosure apply. [Figure 3] Sequence diagram of the setup / reconfiguration procedure for a radio resource control (RRC) connection to which exemplary embodiments of this disclosure apply. [Figure 4] Schematic diagram illustrating usage scenarios for high-speed, high-capacity communication (eMBB: enhanced Mobile Broadband), massive simultaneous connection communication (mMTC: massive Machine Type Communications), and ultra-reliable and low-latency communication (URLLC: Ultra Reliable and Low Latency Communications) to which exemplary embodiments of this disclosure apply. [Figure 5] Block diagram illustrating an exemplary 5G system architecture for V2X (vehicle to everything) communication in a non-roaming scenario to which exemplary embodiments of this disclosure apply. [Figure 6] An example diagram of PRACH preamble resource partitioning according to the current technical specifications. [Figure 7] An illustrative diagram of the SSB-RO mapping as defined in the current TS when used for multi-PRACH transmission according to one embodiment. [Figure 8A] Exemplary diagrams illustrating how RO groups and preambles may be determined for multi-PRACH transmissions according to each embodiment of the present disclosure. [Figure 8B]Other illustrative diagrams illustrating how RO groups and preambles may be determined for multi-PRACH transmissions according to each embodiment of this disclosure. [Figure 9] Exemplary diagrams illustrating how the set of preambles may be determined for multi-PRACH transmissions according to each embodiment of the present disclosure. [Figure 10A] An example diagram illustrating how to determine the preamble for each RO group for 2-PRACH transmission according to the current technical specifications. [Figure 10B] An illustrative diagram illustrating how to determine a preamble for each RO group for 2-PRACH transmission according to various embodiments of this disclosure. [Figure 11] An illustrative diagram showing how to determine a preamble for each SSB index and each RO group according to sequential mapping for multi-PRACH transmissions according to various embodiments of this disclosure. [Figure 12] An illustrative diagram of the multi-PRACH transmission in Figure 11 within a set period of 10 ms according to various embodiments of the present disclosure. [Figure 13] An illustrative diagram showing how to determine a preamble for each SSB index and each RO group according to a cyclic mapping for multi-PRACH transmissions, according to various embodiments of this disclosure. [Figure 14] An illustrative diagram showing how a first preamble set may be mapped to an RO group set for multi-PRACH transmissions according to various embodiments of the present disclosure. [Figure 15] An illustrative diagram showing how a second preamble set may be mapped to the RO group set shown in Figure 14 for multi-PRACH transmissions according to various embodiments of this disclosure. [Figure 16] Exemplary diagrams of multi-PRACH transmissions within a set period of 20ms according to various embodiments of the present disclosure, as shown in Figures 14 and 15. [Figure 17] An illustrative diagram showing how table-based notifications may be used to notify two preamble sets for multi-PRACH transmissions in various embodiments of this disclosure. [Figure 18]Exemplary diagram of multi-PRACH transmission in FIG. 17 within a 20 ms setting period according to various embodiments of the present disclosure [Figure 19] Exemplary diagram of how each preamble in a preamble set can be mapped to two or more RO groups for multiple multi-PRACH transmissions in a frequency division multiplexing (FDM) scheme according to various embodiments of the present disclosure [Figure 20] Exemplary diagram of a table showing the mapping between preambles in a preamble set and RO groups associated with SSB indexes for multiple multi-PRACH transmissions according to various embodiments of the present disclosure [Figure 21] Exemplary diagram of an alternative version of the table in FIG. 20 where each preamble can be mapped to two or more RO groups according to various embodiments of the present disclosure [Figure 22] Flowchart of a UE according to various embodiments of the present disclosure [Figure 23] Flowchart of a gNB according to various embodiments of the present disclosure [Figure 24] Exemplary diagram of the flow of interaction between a UE and a gNB in a 4-step RACH procedure according to various embodiments of the present disclosure [Figure 25] Flowchart showing a communication method according to various embodiments of the present disclosure [Figure 26] Schematic block diagram of an exemplary communication device with a single antenna according to various embodiments of the present disclosure [Figure 27] Schematic block diagram of another exemplary communication device with multiple antennas according to various embodiments of the present disclosure

[0014] Those skilled in the art can understand that the elements in the figures are clearly and simply explained and are not necessarily drawn to a certain scale. For example, for better understanding of the present embodiment, the dimensions of some of the elements in the figures, block diagrams, or flowcharts may be exaggerated with respect to other elements.

Modes for Carrying Out the Invention

[0015] Some embodiments of this disclosure will be described, by example, with reference to the drawings. Similar reference numerals and letters in the drawings refer to similar or equivalent elements.

[0016] In particular, the overall system architecture envisions an NG-RAN (Next Generation Radio Access Network) with gNBs, which terminate the NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) protocols and control plane (RRC) protocols for user equipment (UEs). The gNBs are interconnected with each other via the Xn interface. Furthermore, the gNBs are connected to the NGC (Next Generation Core) via the Next Generation (NG) interface, more specifically to the AMF (Access and Mobility Management Function) (e.g., a specific core entity that performs the AMF) via the NG-C interface, and to the UPF (User Plane Function) (e.g., a specific core entity that performs the UPF) via the NG-U interface. The NG-RAN architecture 100 is shown in Figure 1 (see, for example, Section 4 of 3GPP TS 38.300 v16.3.0).

[0017] The user plane protocol stack in NR (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, all of which terminate at the gNB on the network side. In addition, a new access layer (AS) sublayer (SDAP, Service Data Adaptation Protocol) is introduced on top of PDCP (see, for example, Section 6.5 of 3GPP TS 38.300). A control plane protocol stack is also defined in NR (see, for example, Section 4.4.2 of TS 38.300). An overview of Layer 2 functionality is described in Section 6 of TS 38.300. The PDCP, RLC, and MAC sublayer functionalities are described in Sections 6.4, 6.3, and 6.2 of TS 38.300, respectively. The RRC layer functionality is described in Section 7 of TS 38.300. Furthermore, sidelink communication was introduced in 3GPP TS 38.300 v16.3.0. Sidelink supports direct communication between UEs using sidelink resource allocation mode, physical layer signals / physical layer channels, and physical layer procedures (see, for example, Section 5.7 of TS 38.300).

[0018] For example, the Medium-Access-Control (MAC) layer handles scheduling and scheduling-related functions, including logical channel multiplexing and processing of various numerologies.

[0019] The Physical Layer (PHY) is responsible for, for example, encoding, PHY HARQ processing, modulation, multi-antenna processing, and mapping signals to appropriate physical time-frequency resources. The Physical Layer also handles the mapping of transport channels to physical channels. The Physical Layer provides services to the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for transmitting a particular transport channel, and each transport channel is mapped to a corresponding physical channel. For example, physical channels on the uplink include the Physical Random Access Channel (PRACH), Physical Uplink Shared Channel (PUSCH), and Physical Uplink Control Channel (PUCCH), as well as the Physical Downlink Shared Channel (PDSCH), Physical Downlink Control Channel (PDCCH), and Physical Broadcast Channel (PBCH) on the downlink. Furthermore, physical sidelink channels include the Physical Sidelink Control Channel (PSCCH), Physical Sidelink Shared Channel (PSSCH), Physical Sidelink Feedback Channel (PSFCH), and Physical Sidelink Broadcast Channel (PSBCH).

[0020] NR use cases / deployment scenarios include high-speed, high-capacity communication (eMBB), ultra-high-reliability, low-latency communication (URLLC), and / or massive simultaneous connection communication (mMTC), and these services have diverse requirements regarding data rate, latency, and coverage. For example, eMBB is expected to support peak data rates of the order of three times that provided by IMT-Advanced (20 Gbps for downlink and 10 Gbps for uplink) and user-perceived data rates. In contrast, URLLC has more stringent requirements, including extremely low latency (user plane latency of 0.5 ms for UL and DL respectively) and high reliability (1-10 ms within 1 ms). -5 ) and are imposed. Finally, in mMTC, a high connectivity density (1,000,000 devices / km in urban environments) is preferred. 2 ), wide coverage in harsh environments, and extremely long-lasting batteries (15 years) for low-cost devices may be required.

[0021] Therefore, OFDM numerology suitable for one use case (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) may not work well for another use case. For example, low-latency services may preferably require shorter symbol lengths (and thus larger subcarrier spacings) and / or fewer symbols per scheduling interval (also known as TTI) than mMTC services. Furthermore, in configuration scenarios with large channel delay spreads, longer CP lengths may be preferred than in scenarios with smaller delay spreads. To maintain a similar level of CP overhead, the subcarrier spacing should be optimized according to the delay spread. NR may support two or more values ​​for subcarrier spacing. Currently, subcarrier spacings of 15kHz, 30kHz, 60kHz, etc., are considered. The symbol length Tu and subcarrier spacing Δf are directly related by the equation Δf = 1 / Tu. As with LTE systems, the term "resource element" can be used to represent the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0022] In the new 5G-NR wireless system, resource grids for subcarriers and OFDM symbols are defined for each numerology and carrier, for both the uplink and downlink. Each element of the resource grid is called a resource element and is identified based on its frequency index in the frequency domain and its symbol position in the time domain (see 3GPP TS 38.211 v16.3.0).

[0023] Schematic diagram 200 in Figure 2 shows the functional division between NG-RAN and 5GC. The logical nodes of NG-RAN are gNB or ng-eNB. The logical nodes of 5GC are Access and Mobility Management Function (AMF), User Plane Function (UPF), and Session Management Function (SMF).

[0024] In particular, gNB and ng-eNB handle the following key functions: — Radio resource management functions such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, and dynamic allocation (scheduling) of resources to UEs on both uplink and downlink; — Compression, encryption, and integrity protection of the IP header of the data; — Selection of the AMF when the UE attaches if routing to the AMF cannot be determined from the information provided by the UE; — Routing user plane data for UPF; — Routing of control plane information to AMF; — Setting up and disconnecting connections; — Scheduling and sending paging messages; — Scheduling and transmission of system broadcast information (originating from AMF or OAM); — Setting up measurements and reporting for mobility and scheduling; — Transport-level packet marking on the uplink; — Session management; — Support for network slicing; — Mapping for QoS flow management and data radio bearers; — Support for UEs in RRC_INACTIVE state; — Non-Access Stratum (NAS) message delivery function; — Sharing of wireless access networks; ― Dual connectivity; — Close collaboration between NR and E-UTRA.

[0025] The Access and Mobility Management Function (AMF) handles the following key functions: — A function to terminate signaling in the Non-Access Stratum (NAS); — Security of NAS signaling; — Access Stratum (AS) security controls; — Core Network (CN) node-to-node signaling for mobility between 3GPP access networks; — Reachability of the UE in idle mode (including control and execution of paging retransmissions); — Management of registered areas; — Support for intra-system and inter-system mobility; — Access authentication; — Access authorization including roaming permission checks; — Mobility management and control (enrollment and policies); — Support for network slicing; — Selection of Session Management Function (SMF).

[0026] Furthermore, the User Plane Function (UPF) handles the following key functions: — Anchor points for intra-RAT mobility / inter-RAT mobility (where applicable); — External PDU (Protocol Data Unit) session points for interconnection with data networks; — Packet routing and forwarding; — Packet inspection and enforcement of policy rules in the user plane; — Reporting traffic usage; — Uplink classifier that supports routing of traffic flow to data networks; — Branching point for supporting multi-homed PDU sessions; ― QoS processing for the user plane (e.g., packet filtering, gating, UL / DL rate enforcement); — Verification of upstream link traffic (mapping to SDF QoS flow); — Buffering of downlink packets and triggering of downlink data notifications.

[0027] Finally, the Session Management Function (SMF) handles the following main functions: — Session management; — Assignment and management of IP addresses for UEs; — UPF selection and control; — A traffic steering configuration feature in User Plane Functions (UPF) for routing traffic to the appropriate destination; — Policy enforcement and QoS for the control unit; — Notification of downlink data.

[0028] Sequence diagram 300 in Figure 3 shows some of the interactions between the UE, gNB, and AMF (5GC entities) during the transition of the UE from RRC_IDLE to RRC_CONNECTED in the NAS portion (see TS 38.300 v16.3.0). The transition steps are as follows: 1. The UE requests that a new connection be set up from the RRC_IDLE state. 2 / 2a. The gNB completes the RRC setup procedure. Note: Scenarios in which the gNB rejects the request are described below. 3. In RRCSetupComplete, the first NAS message from the UE, sent via piggyback, is sent to the AMF. 4 / 4a / 5 / 5a. Additional NAS messages may be exchanged between the UE and the AMF. See reference

[22] in TS 23.502 (3GPP TS 23.122: “Non-Access Layer (NAS) Functions Related to Mobile Stations in Idle Mode”). 6. The AMF prepares the UE context data (including PDU session context, security key, UE radio capability, and UE security capability, etc.) and sends it to the gNB. 7 / 7a. gNB activates AS security with UE. 8 / 8a. The gNB performs a reconfiguration to set up SRB2 and DRB. 9. The gNB notifies the AMF that the setup procedure is complete.

[0029] RRC is a higher-layer signaling protocol used for configuring UEs and gNBs. Specifically, in this transition, the AMF creates UE context data (including, for example, PDU session context, security keys, UE radio capabilities, UE security capabilities, etc.) and sends it to the gNB via an INITIAL CONTEXT SETUP REQUEST. The gNB then activates AS security with the UE, which is done by the gNB sending a SecurityModeCommand message to the UE, and the UE responding to the gNB with a SecurityModeComplete message. Subsequently, the gNB performs a reconfiguration to establish the Signaling Radio Bearer 2 (SRB2) and Data Radio Bearer (DRB), which is done by the gNB sending an RRCReconfiguration message to the UE, and the gNB receiving an RRCReconfigurationComplete from the UE in response. For signaling-only connections, the RRCReconfiguration step is omitted because SRB2 and DRB are not set up. Finally, the gNB notifies the AMF that the establishment procedure is complete by sending an INITIAL CONTEXT SETUP RESPONSE.

[0030] Schematic diagram 400 in Figure 4 illustrates several use cases for 5G NR. The 3rd generation partnership project NR (3GPP NR) considers three use cases envisioned to support a wide variety of services and applications through IMT-2020. Phase 1 technical specifications for high-speed, high-capacity communication (eMBB) have been determined. Current and future work includes further expansion of eMBB support, as well as standardization for ultra-high reliability, low-latency communication (URLLC) and massive simultaneous connection communication (mMTC). Figure 4 shows some examples of IMT usage scenarios envisioned for 2020 and beyond (see, for example, Figure 2 in ITU-R M.2083).

[0031] URLLC use cases have stringent requirements regarding capabilities such as throughput, latency, and availability, and are envisioned as one means of realizing future vertical applications such as wireless control of industrial manufacturing or production processes, telemedicine surgery, power distribution automation in smart grids, and transportation safety. The ultra-high reliability of URLLC is supported by identifying the technology to meet the requirements set by TR 38.913. For NR URLLC in Release 15, key requirements include a target user plane latency of 0.5 ms for UL (uplink) and 0.5 ms for DL ​​(downlink). Typical URLLC requirements for a single packet transmission are a BLER (block error rate) of 1E-5 for a packet size of 32 bytes with a user plane latency of 1 ms.

[0032] From a physical layer perspective, several ways to improve reliability are possible. Current approaches to reliability improvements include defining separate CQI tables for URLLC, a more compact DCI format, and PDCCH iterations. However, as NR becomes more stable and development progresses (regarding key requirements for NR URLLC), the scope for achieving ultra-high reliability may expand. Specific use cases for NR URLLC in Release 15 include augmented reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0033] Furthermore, the technical enhancements targeted by NR URLLC aim to improve latency and reliability. Technical enhancements for latency improvement include configurable neurology, mini-slot-based scheduling with flexible mapping, grant-free (configured grant) uplink, mini-slot-level repetition on data channels, and preemption on downlink. Preemption means that a transmission for which resources have already been allocated is aborted, and those resources are used for another transmission requested later with lower latency / higher priority requirements. Thus, a transmission that has already been permitted is preempted by a later transmission. Preemption applies regardless of the specific service type. For example, a transmission of service type A (URLLC) can be preempted by a transmission of service type B (e.g., eMBB). Technical enhancements related to reliability include a dedicated Channel Quality Indicator (CQI) / Modulation and Coding Scheme (MCS) table for the 1E-5 target BLER.

[0034] The use case for mMTC (Massively Multiple Connections Communication) is characterized by a very large number of connected devices transmitting relatively small amounts of data, which are generally less affected by latency. These devices need to be low-cost and have extremely long battery life. From a noise reduction (NR) perspective, utilizing a very narrow bandwidth is one possible solution to achieve power savings from a UE perspective and enable long battery life.

[0035] As described above, the range of reliability in NR is expected to broaden. One important requirement in all cases, especially for URLLC and mMTC, is high or very high reliability. Several mechanisms can be considered to improve reliability from both a radio and network perspective. In general, there are several important areas that can help improve reliability. These areas include compact control channel information, data channel / control channel repetition, and diversity related to the frequency domain, time domain, and / or spatial domain. These areas are generally applicable to reliability regardless of the specific communication scenario.

[0036] Regarding NR URLLC, further use cases with more stringent requirements are envisioned, such as factory automation, transportation, and power distribution. These stringent requirements include higher reliability (up to 10%), depending on the use case. -6 The advantages include higher availability, a maximum packet size of 256 bytes, time synchronization on the order of a few microseconds (values ​​ranging from 1 to several microseconds depending on the frequency range), and low latency on the order of 0.5 to 1 ms (with a target latency of 0.5 ms specifically for the user plane).

[0037] Furthermore, several technical enhancements are possible for NR URLLC from a physical layer perspective. In particular, enhancements related to the PDCCH (Physical Downlink Control Channel) include a compact DCI, PDCCH repeatability, and increased PDCCH monitoring. Enhancements related to the UCI (Uplink Control Information) include improved HARQ (Hybrid Automatic Repeat Request) and enhanced Channel State Information (CSI) feedback. Enhancements to PUSCH related to minislot-level hopping and retransmission / repeat have also been recognized. The term "minislot" refers to a transmission time interval (TTI) containing fewer symbols than a slot (a slot contains 14 symbols).

[0038] The 5G QoS (Quality of Service) model is based on QoS flows and supports both QoS flows that require a guaranteed flow bitrate (GBR QoS flows) and QoS flows that do not require a guaranteed flow bitrate (non-GBR QoS flows). Therefore, at the NAS level, QoS flows are the finest granularity of QoS differentiation within a PDU session. Within a PDU session, QoS flows are identified by a QoS flow ID (QFI) transmitted in the encapsulation header via the NG-U interface.

[0039] The 5GC establishes one or more PDU sessions for each UE. The NG-RAN establishes at least one Data Radio Bearer (DRB) with each PDU session for each UE, and can then configure additional DRBs for the QoS flow of that PDU session, as described above, for example with reference to Figure 3 (the NG-RAN decides when to configure them). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filtering in the UE and 5GC associates UL and DL packets with QoS flows, and AS-level mapping rules in the UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0040] Block diagram 500 in Figure 5 shows the non-roaming reference architecture for 5G NR (see Section 4.2.1.1 of TS 23.287 v16.4.0). Application functions (AFs) (e.g., external application servers handling 5G services as illustrated in Figure 4) interact with the 3GPP Core Network for the purpose of providing services. For example, they support application influence on traffic routing, access Network Exposure Functions (NEFs), or interact with policy frameworks for policy control (e.g., QoS control) (see Policy Control Functions (PCFs)). Based on the operator's deployment, application functions (AFs) that are considered trusted by the operator may be allowed to interact directly with the relevant Network Functions. Application functions that are not authorized by the operator to directly access Network Functions interact with the relevant Network Functions using an external exposure framework via the NEF.

[0041] Figure 5 further illustrates the functional units of the 5G architecture for V2X communication, namely the Unified Data Management (UDM), Policy Control Function (PCF), Network Exposure Function (NEF), Application Function (AF), Unified Data Repository (UDR), Access and Mobility Management Function (AMF), Session Management Function (SMF), and User Plane Function (UPF) in 5GC, as well as the V2X Application Server (V2AS) and Data Network (DN; e.g., operator-provided services, internet access, or third-party services). All or some of the core network functions and application services may be deployed and run in a cloud computing environment.

[0042] At recent 3GPP RAN1 meetings, it has been agreed that, with respect to multi-PRACH transmissions using the same beam, the concept of RO groups, which include ROs used to transmit a specific number of PRACH transmissions, may be introduced. To distinguish between single-PRACH transmissions and multi-PRACH transmissions, an RO group may consist only of shared ROs (e.g., a shared RO can be used for both single-PRACH and multi-PRACH transmissions) and may be implemented to use different preambles for single-PRACH and multi-PRACH transmissions, or an RO group may consist only of individual ROs (e.g., individual ROs are configured to be used only for multi-PRACH transmissions and are independent of those used for single-PRACH transmissions). The gNB can be set to a value of 1 (e.g., for a single-PRACH transmission) or multiple values ​​(e.g., multiple values ​​for 2, 4, or 8 PRACH transmissions) as the number of PRACH transmissions. If multiple values ​​are set, the number of ROs in the RO group will be equal to the number of PRACH transmissions corresponding to each value. However, the details of how PRACH resources can be distinguished for multi-PRACH transmissions with different PRACH transmission counts are not discussed.

[0043] Furthermore, regarding the periodic scheme in which RO groups are formed, a set of RO groups may be determined or formed based on the number of PRACH transmissions within a period X, and the determined or formed set of RO groups may be repeated every period X (for example, period X is the setting period or cycle for multi-PRACH transmissions). This minimizes the burden on the UE to determine individual sets of RO groups for multi-PRACH transmissions, eliminating the need for the UE to continuously determine the required set of RO groups every period X.

[0044] The PRACH preamble resource (for example, up to 64 preambles are supported per serving cell) is divided to distinguish multiple functions for different purposes. For example, referring to Figure 600 in Figure 6, which shows the existing PRACH preamble division in releases 15, 16, and 17, the PRACH preamble resource is divided into a preamble for CFRA (contention-free random access) 602 and a preamble for CBRA (contention-based random access) 604. The preamble for CBRA 604 includes a preamble for 4-step RACH 606, a preamble for 2-step RACH 608, a preamble for function combination 610 (for example, including preambles for RedCap (reduced capacity), SmallData, slice groups, and message 3 (Msg3) repetition requests), and further, in the remaining available preambles 612, individual preambles 614 for different PRACH transmission counts in multi-PRACH transmissions. For example, if an existing PRACH preamble is reused, separate preambles may be used from the remaining available preamble 612 for two PRACH transmissions 616, four PRACH transmissions 618, and eight PRACH transmissions 620.

[0045] The current TS (Release 15 / 16 / 17) does not specify how PRACH preamble resources for multi-PRACH transmissions are implemented. Using the existing PRACH preamble division according to the current TS to divide individual preambles for multiple values ​​of PRACH transmission counts would result in inefficient use of preamble resources, with insufficient preambles available for other purposes. For example (see Figure 600 in Figure 6), for N SSBs, if we denote the preambles for 2, 4, and 8 PRACH transmissions per SSB as M_1, M_2, and M_3 respectively, then (M_1+M_2+M_3)×N preambles need to be reserved (e.g., individual preambles for 2 PRACH transmissions 616, 4 PRACH transmissions 618, and 8 PRACH transmissions 620 shown in Figure 6). The total number of preambles in one serving cell is 64. To support 2, 4, and 8 PRACH transmissions per SSB, at least M_1=M_2=M_3=1 preamble is required. For a maximum of N=8 SSBs in the low frequency band (e.g., FR1), at least (1+1+1)×8=24 preambles are needed, which can lead to excessive use of preamble resources. Also, for a maximum of N=64 SSBs in the high frequency band (e.g., FR2), at least (1+1+1)×64=192 preambles are needed, which exceeds 64, resulting in a preamble shortage problem.

[0046] Furthermore, the SSB-RO (synchronization signal block to RACH occasion) mapping currently defined in TS is primarily designed for single PRACH transmissions and may not function adequately for multi-PRACH transmissions. For example, referring to Figure 700 in Figure 7, a UE may be configured to transmit eight PRACHs 702 (e.g., PRACH#0 to PRACH#7) within a setup period 708. To achieve the combined gain necessary to improve the coverage performance on the gNB side, it is expected that the same preamble #a will be transmitted for all eight PRACHs. However, within the setup period 708 (e.g., including four SSB-RO association periods 710), the UE can only determine the four ROs (i.e., four RO#i with preamble #a) for the first four PRACH transmissions 704, and the remaining four PRACH transmissions 706 will not be completed. As a result, the gNB will not be able to achieve the combined gain desirable to compensate for the propagation loss of the PRACHs. Therefore, if an RO group consists of shared ROs and the SSB-RO association period is set short, the UE may not be able to determine enough shared ROs for a large number of PRACH transmissions. The UE may only be able to transmit a small number of PRACHs, and the base station (gNB) may not be able to achieve the desired combined gain for preamble detection. Furthermore, even if the SSB-RO association period for each SSB-RO is set longer, the potential problems of excessive preamble use or insufficient preambles are not resolved. For this reason, it is necessary to provide PRACH preamble resources for multi-PRACH transmissions and to define a solution to overcome the above challenges.

[0047] In this disclosure, the UE may be configured to determine RO groups based on the number of PRACH transmissions in a multi-PRACH transmission, and to determine the preambles to be transmitted in the RO groups based on a mapping between preambles and RO groups. An RO group may contain one or more ROs equal to the number of PRACH transmissions in a multi-PRACH transmission. The mapping may be a mapping between one or more preambles and one or more RO groups. The mapping may further be a mapping between preambles, RO groups, and SSB indices. The mapping indicates, for each RO group per SSB index, a preamble selected from a set of preambles defined based on a configurable number of N SSBs and K options for one or more multi-PRACH transmissions. K is referred here to as the index associated with one or more multi-PRACH transmissions and indicates the number of options available for one or more multi-PRACH transmissions. For example, K=1 (e.g., index 1) may represent 2, 4, or 8 PRACH transmissions (e.g., one multi-transmission PRACH transmission including 2, 4, or 8 PRACH transmissions); K=2 (e.g., index 2) may represent 2 and 4, 2 and 8, or 4 and 8 PRACH transmissions (e.g., two multi-transmission PRACH transmissions including 2 and 4, 2 and 8, or 4 and 8 PRACH transmissions); and K=3 (e.g., index 3) may represent 2, 4, and 8 PRACH transmissions (e.g., three multi-transmission PRACH transmissions including 2, 4, and 8 PRACH transmissions). N≧1 and 1≦K≦3 may be the case. Note that the index K is not limited to these three options, and further options may be applicable to embodiments of PRACH transmissions exceeding 8. For example, embodiments with K=4, 5, and 6 may be associated with 16, 32, or 64 PRACH transmissions, respectively. The preamble is transmitted within the RO group using the same beam within a certain time interval.A certain time interval may be referred to as a settable sequence of OFDM symbols, slots, or subframes, or frames, or an SSB-RO association period, or an SSB-RO association pattern period, or a multi-PRACH transmission setting period.

[0048] The set of preambles is configured based on N SSBs and K options for the number of multiple PRACH transmissions. Based on one or more multiple PRACH transmissions, the UE may determine from the set of preambles an RO group and a preamble to be transmitted within that RO group on the same beam, according to a mapping between the preamble, the RO group, and the SSB index (for example, the preamble and RO group are transmitted within the same / single SSB-based beam rather than across multiple SSB-based beams). A preamble may be considered an RO-group-specific preamble for one or more multiple PRACH transmissions on the same SSB beam. The mapping can be implemented based on one of the following solutions: Solution 1, the mapping is rule-based. Solution 2, the mapping is based on explicit notification by the gNB.

[0049] For example, referring to Figure 800 in Figure 8A, the decision may be made within a 10ms time interval 802, during which the preamble set may be used for other purposes in the remaining 20ms time interval 804. In another example, referring to Figure 806 in Figure 8B, the decision may be made within a 30ms time interval 808. In Figure 8A, within the 10ms time interval 802, the transmission period of a multi-PRACH transmission in a single PRACH attempt can be shortened, thereby reducing the delay in initial access compared to eventually distributing preamble resources over a longer period. The longer 30ms time interval 808 in Figure 8B is suitable when there are many multiple PRACH transmissions. Advantageously, the ability to adjust the time intervals to increase the flexibility of setting up the preamble for multi-PRACH transmissions improves the provision of PRACH resources for other purposes.

[0050] In one embodiment, the UE determines the preamble to send to the gNB within the RO group based on a mapping, from the determined RO group or the determined number of PRACH transmissions and SSB index. The SSB index may be the optimal SSB index or an SSB index that satisfies a condition (e.g., exceeds a threshold). The RO group or mapping is determined based on K options for one or more multiple PRACH transmissions. The UE then monitors to receive random access responses (RARs) for the multi-PRACH transmissions.

[0051] In one embodiment, the gNB may configure one or more preamble sets, N SSBs, and K options for the number of multiple PRACH transmissions (for example, K is an index indicating the number of options associated with one or more multiple PRACH transmissions and available for one or more multiple PRACH transmissions). The gNB may generate a DCI that schedules a PDSCH to carry the RAR and sends the RAR to the UE in response to a multiple PRACH transmission (e.g., one received from the UE).

[0052] In one embodiment, the preamble set is configured based on N SSBs and K options for one or more multiple PRACH transmissions (e.g., K is an index indicating the number of options available for one or more multiple PRACH transmissions that are associated with one or more multiple PRACH transmissions). For example, K=1 (e.g., index 1) represents 2, 4, or 8 PRACH transmissions (e.g., one multiple PRACH transmission including 2, 4, or 8 PRACH transmissions); K=2 (e.g., index 2) represents 2 and 4, 2 and 8, or 4 and 8 PRACH transmissions (e.g., two multiple PRACH transmissions including 2 and 4, 2 and 8, or 4 and 8 PRACH transmissions); and K=3 (e.g., index 3) represents 2, 4, and 8 PRACH transmissions (e.g., three multiple PRACH transmissions including 2, 4, and 8 PRACH transmissions). N≧1 and 1≦K≦3 may be the case. Note that index K is not limited to three options, and further options may be applicable to embodiments of PRACH transmissions exceeding eight. For example, embodiments with K=4, 5, and 6 may be associated with 16, 32, and 64 PRACH transmissions, respectively. For example, referring to illustration 900 in Figure 9, a set of preambles 902 consisting of N × K preambles is required for N SSBs and K options for one or more multi-PRACH transmissions. The K options for one or more multi-PRACH transmissions may be notified by the base station through control information such as upper-layer signaling. The set of preambles and one or more multi-PRACH transmissions may be mapped temporally closely but without overlap in the time domain, which advantageously shortens the transmission duration of multi-PRACH transmissions in a single PRACH trial. Here, multi-PRACH transmissions may also be referred to as multiple PRACH transmissions, RO groups, or a single PRACH trial.

[0053] Figure 10A illustrates an example of determining a preamble for each RO group for a 2-PRACH transmission according to current technical specifications. Within two SSB-RO association periods 1002 and 1004, based on the current TS, RO group #0 (e.g., including two ROs, RO#i and RO#j) and two preambles (e.g., preamble #a and preamble #b) are determined for the two PRACHs. Figure 10B illustrates an example of determining a preamble for each RO group for a 2-PRACH transmission according to various embodiments of the present disclosure. Unlike the example in Figure 10A, within one SSB-RO association period 1008, RO group #0 (e.g., including two ROs, RO#i and RO#j) and one preamble (e.g., preamble #a) are determined for the two PRACHs.

[0054] In this solution, preambles are notified for each SSB and each RO group (for one or more PRACH transmissions), and can be thought of as a preamble-to-RO group-to-SSB mapping to provide RO group-specific preambles, for example. Furthermore, based on the number of multiple PRACH transmissions, the UE determines the RO group and, for example, the preamble to transmit for that RO group on the same beam, according to the mapping between preambles, RO groups, and SSB indices. In this solution, a maximum of N × K preambles are required for N SSBs. Also, as shown in Figure 10B, for example, the short transmission duration of multi-PRACH transmissions in a single PRACH attempt can reduce initial access delays. This allows for greater flexibility in configuring preambles for multi-PRACH transmissions and improves the provision of preamble resources for other purposes. Furthermore, it can support different levels of PRACH coverage extension in different sectors / directions. For example, beams with different sectors / directions (e.g., N SSBs) covering different areas may have different coupling losses due to transmission from outdoors to indoors and transmission through trees / buildings / obstacles, thus requiring different values ​​for N and K.

[0055] Examples of preamble resource determination based on this solution are as follows: In the FR1 case based on this solution, if N=8 and K=1, up to 8 preambles may be required to support two PRACH transmissions. Based on the current TS, at least (1+1+1)×8=24 preambles may be required. In the FR1 case based on this solution, if N=8 and K=2, up to 16 preambles may be required to support two and four PRACH transmissions. Based on the current TS, at least (1+1+1)×8=24 preambles may be required. Furthermore, in the FR1 case based on this solution, if N=8 and K=3, up to 24 preambles may be required to support two, four, and eight PRACH transmissions. Based on the current TS, at least (1+1+1)×8=24 preambles may be required. Advantageously, this solution is better suited to the case of multiple PRACH transmissions compared to the current SSB-RO mapping designed for single PRACH transmissions. Furthermore, in scenarios where K=1 or K=2, fewer preamble resources are required.

[0056] In this disclosure, it may be assumed that a gNB has K options for one or more PRACH transmissions in a single serving cell (for example, K is an index indicating the number of options available for one or more PRACH transmissions, associated with one or more PRACH transmissions), where K=1 represents two PRACH transmissions, K=2 represents two and four, two and eight, or four and eight PRACH transmissions, and K=3 represents two, four, and eight PRACH transmissions. Note that the index K is not limited to three options, and further options may be applicable to embodiments of more than eight PRACH transmissions. For example, embodiments with K=4, 5, and 6 may be associated with 16, 32, and 64 PRACH transmissions, respectively. The gNB may have N SSBs. The gNB may have sets of preambles individually (for example, a set may contain N × K preambles as individual settings). The preambles in a set may be configured in a sequential order (e.g., ascending / descending order of preamble index). Based on the index associated with one or more PRACH transmissions, the UE determines the RO groups and the preambles to be transmitted in those RO groups, according to the mapping between preambles and RO groups. The mapping may further be between preambles, RO groups, and SSB indices. The UE may further determine a set of RO groups based on N configurable SSBs and the index associated with one or more PRACH transmissions. Each RO group in the RO group set (e.g., N × K RO groups) corresponds to the number of PRACH transmissions (e.g., in multiple PRACH transmissions) and is associated with an SSB index among the N SSBs.

[0057] The mapping of preambles, RO groups, and SSB indices is rule-based, and the rule is either sequential mapping or cyclic mapping. Figure 11 shows an example illustration 1100 in which a preamble is determined for each SSB index and each RO group according to sequential mapping for a multi-PRACH transmission, according to various embodiments of the present disclosure. Illustration 1100 uses a set 1102 of N=3 SSBs, K=2, and N×K preambles. Each preamble in the set 1102 is sequentially mapped to each RO group in the RO group set 1104. Based on this mapping, in the multi-PRACH transmission 1202, each preamble is transmitted in its respective mapped RO group within a 10ms configuration period 1204, as shown in illustration 1200 of Figure 12.

[0058] Figure 13 also shows an example illustration 1300 of determining a preamble for each SSB index and each RO group according to a cyclic mapping for multi-PRACH transmissions according to various embodiments of the present disclosure. In example 1300, we have N=3 SSBs, K=2, and a set of N×K preambles. The UE determines a preamble for each SSB index and each RO group (corresponding to the number of times PRACH transmissions occur) according to the cyclic mapping. First, as a first step, the first preamble of the set of preambles 1302 (e.g., preamble #0) is mapped to the first RO group of the set of RO groups 1304 (e.g., RO group #0), which is associated with the smallest SSB index (e.g., SSB #0). In the second step, the second preamble of the set of preambles 1302 (e.g., preamble #1) is mapped to the second RO group (e.g., RO group #3) associated with the smallest SSB index (e.g., SSB #0). Then, in the third step, the first and second steps are repeated for the remaining SSB indices (e.g., SSB indices SSB #1 and SSB #2).

[0059] In one embodiment, the rules may be defined by the TS, set by a gNB or UE, or in other similar embodiments. The embodiment in which the rules are defined by the TS has the advantage that it does not require the transmission of signaling for mapping.

[0060] In one embodiment, one or more preamble sets in the time domain may be used for one or more PRACH transmissions. For example, referring to illustrations 1400, 1500, and 1600 in Figures 14, 15, and 16, K=2 and N=3. In two different time intervals 1602 and 1604, two sets of preambles 1402 and 1502 are sequentially mapped to RO group set 1404, respectively. For example, set of preambles 1402 is transmitted in time interval 1602 with RO group set 1404, and set of preambles 1502 is transmitted in time interval 1604 with RO group set 1404. In one embodiment, the preambles of one or more preamble sets may be identical or different from each other. For example, preamble set 1502 includes preamble #0, preamble #1, preamble #2, and preamble #3, which are also included in preamble set 1402. Advantageously, this embodiment allows the gNB to flexibly configure preamble resources in the time domain as needed, based on actual usage of multi-PRACH transmissions or other purposes. One or more sets of preambles may be configured by control information such as upper-layer signaling, downlink control information (DCI), etc. Although two sets of preambles are illustrated, two or more mappings are possible between two or more sets of preambles and RO group set 1404, and each of the two or more sets of preambles may be mapped to the RO group set in the time domain, for example, sequentially, cyclically, or in other similar mapping configurations.

[0061] In one embodiment, the total number of preamble sets mapped to a set of RO groups may differ depending on the index associated with one or more PRACH transmissions. For example, if the index is "1" (e.g., K=1), one set of preambles may be mapped to a set of RO groups; if the index is "2" (e.g., K=2), two sets of preambles may be mapped to a set of RO groups; and other possible variations may be implemented. Furthermore, the total number of preamble sets may differ for each of the N SSBs. In this embodiment, if the index is small, for example K=1, fewer preambles are required, so one set of preambles is sufficient to map to a set of RO groups. This allows the gNB to allocate PRACH resources for other purposes. If the index is large, for example K=3, more preambles are required, so more sets of preambles may be set up to map to a set of RO groups to enable multiple PRACH transmissions. gNB can be more flexible because it can favorably configure the total number of preamble sets, allowing it to allocate more PRACH preamble resources preferentially for other purposes as needed.

[0062] In one embodiment, the number of preambles in a set of preambles may differ from the number of RO groups in a set of RO groups. If the number of preambles is greater than the number of RO groups, any remaining preambles (e.g., preambles not mapped to any RO group) may be left unused. If the number of preambles is less than the number of RO groups, one or more remaining RO groups (e.g., RO groups not mapped to any preamble) may be allocated to other transmissions or left unused. The gNB has the advantage of being able to preferentially allocate more PRACH resources (e.g., remaining RO groups) for other purposes as needed.

[0063] In one embodiment, if a set of preambles (e.g., a first set of preambles) is mapped to a set of RO groups, and the number of preambles in the set of preambles is less than the number of RO groups in the set of RO groups, then, if a subsequent set of preambles (e.g., a second set of preambles) is determined or set, one or more remaining RO groups in the set of RO groups (e.g., RO groups not mapped to any preamble in the first set of preambles) may be mapped to one or more preambles in the subsequent set of preambles. This advantageously overcomes the limitation of small sets of preambles (e.g., the number of preambles in the set of preambles is less than the number of RO groups in the set of RO groups) to support all possible RO groups associated with each SSB index.

[0064] In one embodiment, one or more sets of preambles (e.g., Table 1702 in Figure 17) and a set of RO groups (e.g., the multi-PRACH table shown in Table 1704 in Figure 17) may be shown using two table-based notifications, based on N configurable SSBs and K options for the number of PRACH transmissions (e.g., K being an index associated with one or more PRACH transmissions). Table 1702 shows one or more sets of preambles to be used in the time domain, which may be implicitly determined or set by gNB, for example. The multi-PRACH table 1704 may also be implicitly determined or set by gNB, for example. Each row of Table 1704 shows the association between SSB indices and RO groups, starting with the smallest SSB index (e.g., SSB#0) of the N SSBs (e.g., each row corresponds to an RO group), and each column shows the index of PRACH transmissions for different RO groups. The number of columns depends on the index (for example, 2 columns for K=1, 4 columns for K=2, and 8 columns for K=3). Also, each entry in table 1704 shows the relationship between the SSB index and the RO group (for example, SSB#i, RO#i).

[0065] For example, in Figure 17, with N=3 and K=2, tables 1702 and 1704 show the possible PRACH resources (e.g., preambles and ROs) for two and four PRACH transmissions (since index=K=2). There may be six rows to show the six possible relationships between SSBs and RO groups for two and four PRACH transmissions. For two PRACH transmissions, two columns in the multi-PRACH transmission are sufficient to show the PRACH resources. For four PRACH transmissions, four columns in the multi-PRACH transmission are sufficient to show the PRACH resources. Thus, each preamble of one or more sets of preambles (e.g., the first preamble set 1706 and the second preamble set 1708 shown in table 1702) is mapped to each row in the multi-PRACH table (e.g., each row in table 1704 showing the RO groups of a set of RO groups). Referring to Figure 1800 in Figure 18, the mapped preamble of the first preamble set 1706 may be transmitted within time interval 1802, and the mapped preamble of the second preamble set 1708 may be transmitted within time interval 1804. Note that there are other possibilities that represent one or more sets of preambles and multi-PRACH tables, and tables 1702 and 1704 are just two such possibilities.

[0066] In one embodiment, the preambles in a set of preambles may be identical or different from the preambles in other sets of preambles. One or more ROs in RO group #A for a number of PRACH transmissions may be included in RO group #B for the same or different number of PRACH transmissions. Different preambles in a set may be mapped to RO group #A and RO group #B, respectively. For example, for two PRACH transmissions, preamble #0 may be mapped to RO group #0 for UE#0 (e.g., consisting of RO#i and RO#(i+1)), and preamble #1 may be mapped to RO group #1 for UE#1 (e.g., consisting of RO#i and RO#(i+1)). The gNB may be configured to distinguish between RO group #0 and RO group #1 transmitted by UE#0 and UE#1 based on the detection of different preambles #0 and #1. In another example, preamble #0 may be mapped to RO group #0 (consisting of RO#i and RO#(i+1)) for two PRACH transmissions of UE#0, and preamble #1 may be mapped to RO group #1 (e.g., consisting of RO#i, RO#(i+1), RO#(i+4), and RO#(i+5)) for four PRACH transmissions of UE#1. Also, in one embodiment, if the number of preambles in the set is less than N × K, depending on the mapping order, the number of preambles used for a small number of PRACH transmissions may be less (or more) than the number of preambles used for a large number of PRACH transmissions (for example, in preamble set 1708 in Figure 17, three preambles (preamble #0, preamble #1, preamble #2) may be used for two PRACH transmissions, and one preamble (preamble #3) may be used for four PRACH transmissions).

[0067] In one embodiment, in a frequency division multiplexing (FDM) scheme, each preamble in a set of preambles may be mapped to two or more RO groups in a set of RO groups. Each RO group in the set of RO groups may be, for example, multiple FDM-mapped RO groups that can be distinguished from one another in the frequency domain. The mapping may be performed based on the following options: Option a, if there is only one preamble in the set of preambles, it is mapped to all rows of the multi-PRACH table; Option b, if there are two or more preambles in the set of preambles, sequential mapping or cyclic mapping is repeatedly used (for example, as performed in Figures 11 and 13, respectively). For example, in sequential mapping, the preambles in the set of preambles are arranged in a sequential order, and this order is repeated multiple times to match the size of the set of RO groups. Referring to Figure 1900 in Figure 19, assuming two preambles, N=3 SSBs, and index=K=2, sequential mapping is repeatedly used between a set of preambles 1902 containing two preambles (preamble #0 and preamble #1) and a set of RO groups 1904 containing six RO groups. For example, in Figure 1900, preamble #0 and preamble #1 are mapped to RO groups #0 and #1, RO groups #2 and #3, and RO groups #4 and #5, respectively. This embodiment allows for an advantageous reduction in the amount of PRACH preamble used.

[0068] Alternatively, the gNB may determine the number of preambles and the corresponding preambles for each of the K options and notify the UE. For example, if K=3, the number of preambles and the corresponding preambles are determined for each of the 2, 4, and 8 PRACH transmissions. The gNB and / or UE then determine the mapping between the set of preambles and the set of RO groups. The corresponding preambles may be mapped to each of the RO groups (e.g., N × K RO groups). Some of the corresponding preambles may be mapped to two or more RO groups, and some of the RO groups may be mapped to two or more corresponding preambles. The number of corresponding preambles for a first multi-PRACH transmission (e.g., including 2 PRACH transmissions) may be greater than or less than the number of corresponding preambles for a second multi-PRACH transmission (e.g., including 4 PRACH transmissions).

[0069] In one embodiment, the gNB sets up N SSBs and K options for one or more multiple PRACH transmissions in a single serving cell (for example, K represents an index associated with one or more multiple PRACH transmissions), where K=1 represents 2, 4, or 8 PRACH transmissions, K=2 represents 2 and 4, 2 and 8, or 4 and 8 PRACH transmissions, and K=3 represents 2, 4, and 8 PRACH transmissions. Note that the index K is not limited to three options, and further options may be applicable for embodiments of more than 8 PRACH transmissions. For example, embodiments with K=4, 5, and 6 may be associated with 16, 32, or 64 PRACH transmissions, respectively. Based on the number of multiple PRACH transmissions, the UE may determine RO groups and preambles to transmit within that RO group on the same beam, according to the mapping of preambles, RO groups, and SSB indices.

[0070] The mapping may be based on explicit notification. In one embodiment, in random access (RA) without PDCCH order, the mapping may be between a preamble, an RO group, and an SSB index, and the mapping is an explicit notification from one or a combination of a master information block (MIB), a system information block (SIB), upper layer parameters, and downlink control information (DCI). The UE may determine the preamble based on the number of multiple PRACH transmissions. In the case of RA with PDCCH order, the explicit notification may directly indicate the preamble (within the set of preambles) for multiple PRACH transmissions in the DCI. In another embodiment, a multi-PRACH table like Table 2000 in Figure 20 may be set up based on N SSBs and K options (e.g., K is an index associated with one or more multiple PRACH transmissions) (e.g., set up in an MIB or SIB). Explicit notifications (for example, in the MIB or SIB for RAs without a PDCCH order, or in the notification field of the DCI for RAs with a PDCCH order) may indicate rows in the multi-PRACH table. Each row in Table 2000 shows the mapping between the preamble in the set of preambles and the RO group associated with the SSB index. This embodiment can advantageously provide greater flexibility from a gNB perspective (compared to setting up a separate table or list of preambles from a set of one or more RO groups).

[0071] In one embodiment, the UE receives explicit notification (e.g., from the gNB) to determine which preamble to transmit within an RO group on the same beam, according to a mapping between preambles, RO groups, and SSB indices in the FDM scheme. Each RO group in a set of RO groups may be distinguished from one another in the frequency domain, for example, by multiple FDM-decoded RO groups. Also in the FDM scheme, a preamble may be mapped to two or more RO groups in a set of RO groups (e.g., to two or more rows in a multi-PRACH table). For example, Table 2100 in Figure 21 is generated under the assumption that there are two preambles, N=3 SSBs, and K=2 in a set of preambles (e.g., a set containing preamble #0 and preamble #1). In Table 2100, preamble #0 and preamble #1 are mapped to RO groups so as to be used repeatedly, for example, preamble #0 is mapped to RO group in row 2102 and preamble #1 is mapped to RO group in row 2104. This embodiment allows for a favorable reduction in the amount of PRACH preamble used.

[0072] In one embodiment, for example, referring to Figure 1900 in Figure 19, if the set of preambles 1902 has two preambles (e.g., preamble #0 of the first preamble and preamble #1 of the second preamble), the first and second preambles may be mapped to the first half (e.g., from RO group index #0 to RO group index #(N×K / 2-1)) and the second half (e.g., from RO group index #(N×K / 2) to RO group index #(N×K-1)) of the RO group index of the set of RO groups 1904.

[0073] Furthermore, all embodiments described herein may apply to CSI-RS based beams rather than SSB-based beams, and may also apply when RO groups consist of shared ROs with individual preambles, or when RO groups consist of individual ROs.

[0074] The mappings discussed in the embodiments disclosed herein ensure that, in code division multiplexing (CDM), FDM, spatial division multiplexing (SDM), or other applicable similar schemes, only mapped preambles are transmitted in multi-PRACH transmissions from the UE. In the CDM scheme (for example, applicable to the embodiments shown in Figures 11-18 and 20), preambles in a set of preambles are distinguished in the code domain (e.g., the preamble domain). In the FDM scheme (for example, applicable to the embodiments shown in Figures 19 and 21), a set of RO groups may be determined or set for multiple values ​​of the number of PRACH transmissions. Each RO group in the set of RO groups is distinguished from one another in the frequency domain. Each preamble in the set of preambles may be mapped to two or more RO groups for the same number of PRACH transmissions. Furthermore, in the SDM method, different sets of preambles may be configured for different transmission / reception points (TRPs), different cells, different sets of beams, or other similar entities. For example, each set of preambles may be applied to each TRP, each cell, or each set of beams.

[0075] Furthermore, the embodiments described herein can be implemented not only for multi-PRACH transmissions on the same beam, but also for multi-PRACH transmissions on different beams. Additionally, for multiple PRACH transmissions, the RO group may be divided into two or more sub-RO groups, and the mapping may be between the preamble, sub-RO group, and SSB index. Similarly, the multiple PRACH transmissions may be transmitted on the same beam or on different beams.

[0076] Figure 22 shows a flowchart 2200 of a UE according to various embodiments of the present disclosure. In step 2202, the UE may determine or set one or more sets of preambles, N SSBs, and K options for the number of multi-PRACH transmissions (e.g., K is an index associated with one or more multi-PRACH transmissions). In step 2204, the UE implicitly or explicitly determines a preamble for each SSB index and each RO group (e.g., according to embodiments described in the present disclosure). In step 2206, the UE may determine or select RO groups having the corresponding preambles determined in step 2204 for multi-PRACH transmissions, based on SSB-RSRP measurements and corresponding thresholds. In step 2208, the UE may monitor to receive Random Access Responses (RARs) for multi-PRACH transmissions (e.g., from gNBs).

[0077] Figure 23 shows a flowchart 2300 of a gNB according to various embodiments of the present disclosure. In step 2302, the gNB may configure one or more sets of preambles, N SSBs, and K options for the number of multiple PRACH transmissions (e.g., K is an index associated with one or more multiple PRACH transmissions). In step 2304, the gNB may configure a multiPRACH table and / or preamble mapping (e.g., according to an embodiment of explicit notification based on Figure 20). Step 2304 may be omitted in embodiments based on Figures 11 to 18. In step 2306, the gNB generates a DCI that schedules a PDSCH to carry the RAR and sends the RAR to the UE in response to a multiPRACH transmission (e.g., received from the UE).

[0078] In one embodiment, the gNB is configured to generate a mapping between preambles and RO groups based on one or more sets of preambles, the number of SSBs, and an index associated with one or more PRACH transmissions, and may signal that mapping to the UE.

[0079] Figure 24 illustrates an example of the flow of interaction between UE2402 and gNB2404 in a four-step RACH procedure according to various embodiments of this disclosure. In phase 2406, gNB2404 may set up one or more sets of preambles, N SSBs, and K options for the number of multiple PRACH transmissions (e.g., K is an index associated with one or more multiple PRACH transmissions) for a multi-PRACH transmission. In phase 2408, UE2402 may implicitly or explicitly determine a preamble for each SSB index and each RO group (e.g., according to embodiments described in this disclosure). In phase 2410, UE2402 may send a multi-PRACH transmission (e.g., Msg1) based on the RO groups having the corresponding preambles determined in phase 2408 and monitor to receive a RAR of the multi-PRACH transmission from gNB2404. In phase 2412, gNB2404 generates a DCI that schedules a PDSCH to carry the RAR and may send the RAR (e.g., Msg2) to UE2402 in response to the multi-PRACH transmission. In phase 2414, UE2402 sends the scheduled transmission (e.g., Msg4) to gNB2404, and gNB2404 sends Msg4 to UE2402 for conflict resolution.

[0080] Figure 25 shows a flowchart 2500 illustrating a communication method according to various embodiments of the present disclosure. In step 2502, a random access channel occasion (RO) group is determined based on the number of physical random access channel (PRACH) transmissions in multiple PRACH transmissions. In step 2504, a preamble is determined to be used for an RO group containing one or more ROs, based on a mapping between one or more preambles and one or more RO groups. In step 2506, the preamble is transmitted.

[0081] Figure 26 shows a schematic partial cross-sectional view of a communication device 2600 that can be implemented according to the various embodiments and examples shown in Figures 1 to 25. The communication device 2600 can be implemented as a UE or base station according to various embodiments.

[0082] The various functions and operations of the communication device 2600 are arranged in multiple layers according to a hierarchical model. In this model, lower layers report to higher layers in accordance with 3GPP technical specifications and receive commands from higher layers. For simplicity, the details of the hierarchical model are not described in this disclosure.

[0083] As shown in Figure 26, the communication device 2600 may comprise a circuit 2614, at least one radio transmit (Tx) chain 2602 (also referred to here as the transmitter 2602), at least one radio receive (Rx) chain 2604 (also referred to here as the receiver 2604), and at least one antenna 2612 (for simplification, only one antenna is depicted in Figure 26 for illustrative purposes). The circuit 2614 may include at least one control unit 2606. The control unit 2606 is used to perform tasks designed to be performed by at least one control unit 2606, with the assistance of software and hardware. Tasks include controlling communication with one or more other communication devices in the radio network. The circuit 2614 may further comprise at least one transmit signal generation unit 2608 and at least one receive signal processing unit 2610. At least one control unit 2606 can control, under the control of at least one control unit 2606, at least one transmit signal generation unit 2608 for generating signals (e.g., baseband signals) to be transmitted via at least one radio transmitter 2602 to one or more other communication devices (e.g., base station communication devices), and at least one receive signal processing unit 2610 for processing signals (e.g., baseband signals) received from one or more other communication devices via at least one radio receiver 2604, under the control of at least one control unit 2606. The at least one transmit signal generation unit 2608 and the at least one receive signal processing unit 2610 may be standalone modules of the communication device 2600 communicating with at least one control unit 2606 for the functions described above, as shown in Figures 1-25. Alternatively, the at least one transmit signal generation unit 2608 and the at least one receive signal processing unit 2610 may be included in at least one control unit 2606. It will be apparent to those skilled in the art that the arrangement of these functional modules is flexible and may vary according to actual needs and / or requirements. Data processing, virtual memory, and other related control devices can be provided on a suitable circuit board and / or within a chipset.In various embodiments, during operation, at least one radio transmitter 2602, at least one radio receiver 2604, and at least one antenna 2612 may be controlled by at least one control unit 2606. It will be understood that the communication device 2600 may include multiple antennas 2712, for example, as shown in the communication device 2700 of Figure 27. The multiple antennas 2712 can be connected to the corresponding Tx chains 2702 and Rx chains 2704 via a switcher or switch point. Alternatively, each of the multiple antennas 2712 may be connected to the corresponding Tx chain or Rx chain.

[0084] The communication device 2600 provides the functions necessary for resource allocation for multi-PRACH transmission during operation. For example, the communication device 2600 may be an UE, and the circuit 2614 may, during operation, determine a group of ROs containing one or more random access channel occasions (ROs) based on the number of physical random access channel (PRACH) transmissions in multiple PRACH transmissions, and determine the preamble to be used for the RO group based on the mapping between one or more preambles and one or more RO groups. The transmission unit 2602 transmits the preamble during operation.

[0085] Circuit 2614 is configured to determine one or more RO groups and one or more preambles based on the number of synchronous signal blocks (SSBs) and an index associated with one or more PRACH transmissions, each of which is associated with an SSB index of a synchronous signal block (SSB). The number of preambles in one or more preambles may be greater than the number of RO groups in one or more RO groups, and there may be one or more preambles that remain unused and unmapped. The index may be such that 1 represents 2, 4, or 8 PRACH transmissions, 2 represents 2 and 4, 2 and 8, or 4 and 8 PRACH transmissions, and 3 represents 2, 4, and 8 PRACH transmissions.

[0086] Mapping may be applied to a time interval, which may be a set of association periods between consecutive OFDM symbols, slots, subframes, frames, synchronous signal blocks (SSBs) and random access channel occasions (SSB-ROs), or an SSB-RO association pattern period, during which the transmitter 2402 can transmit preambles in RO groups. In the mapping, one or more preambles may be mapped sequentially or cyclically to one or more RO groups. One of the one or more preambles may be mapped to one of the one or more RO groups. Each of the one or more RO groups may be mapped to the same or different preambles. The total number of one or more preambles in the mapping or the total number of one or more RO groups in the mapping may vary based on the number of synchronous signal blocks (SSBs) and the index associated with one or more PRACH transmissions.

[0087] The number of preambles in one or more preambles may differ from the number of RO groups in one or more RO groups, and one or more remaining RO groups in one or more RO groups that are not mapped to one or more preambles may be allocated to other transmissions or remain unused. A first preamble set containing one or more preambles may be mapped to a set of RO groups containing one or more RO groups, and the number of preambles in the first preamble set may be less than the number of RO groups in the set of RO groups, and circuit 2614 may be configured to map one or more preambles from a second preamble set to one or more remaining RO groups in the set of RO groups.

[0088] One or more preambles may be a first preamble set, and the mapping between the first preamble set and one or more RO groups may be a first mapping. There may be at least a second mapping between at least a second preamble set containing one or more preambles and one or more RO groups, and the at least second preamble set containing one or more preambles may be identical or different from the first preamble set. Each preamble set may be mapped to one or more RO groups sequentially or cyclically in the time domain. One or more preambles may be a first preamble set, and the mapping between the first preamble set and one or more RO groups may be a first mapping, and there may be at least a second mapping between at least a second preamble set containing one or more preambles and one or more RO groups, and the total number of preambles mapped to one or more RO groups in the first mapping may be different from that in the second mapping. Each set of the first preamble set and at least the second preamble set may be assigned to each of one or more transmit / receive points, or each of one or more cells, or each of one or more beamsets.

[0089] There may be one or more multiple PRACH transmissions, and each of the one or more RO groups may be associated with one of the one or more multiple PRACH transmissions. The RO groups may be determined from one or more RO groups based on the SSB index of the number of synchronous signal blocks (SSBs).

[0090] The mapping may take the form of a first table showing a set of one or more preambles to be used in the time domain, and a second table showing a set of RO groups based on the index and number of SSBs associated with one or more PRACH transmissions, and the circuit 2614 may be configured to determine the RO groups and preambles based on the first and second tables. The mapping may also indicate that in a frequency division multiplexing (FDM) scheme, each preamble in a set of preambles containing one or more preambles is mapped to two or more RO groups.

[0091] The mapping may further be a mapping between preambles, RO groups, and SSB indices, and may be an explicit notification from one or a combination of Master Information Blocks (MIBs), System Information Blocks (SIBs), Upper Layer Parameters, and Downlink Control Information (DCIs).

[0092] Each of one or more RO groups may contain multiple sub-RO groups, and the mapping may further be a mapping between a preamble, a sub-RO group of one or more RO groups, and a synchronization signal block (SSB) index. The mapping may further be a mapping between a preamble, an RO group within one or more RO groups, and a CSI-RS index based on the number of channel state information reference signals (CSI-RS) and an index associated with one or more PRACH transmissions.

[0093] The communication device 2600 may be a base station, and the circuit 2614 may, during operation, determine a mapping between one or more preambles and one or more random access channel occasion (RO) groups based on indices associated with one or more physical random access channel (PRACH) transmissions. The transmitter 2602 may, during operation, signal the mapping to the communication device.

[0094] The mapping is further a mapping between preambles of one or more preambles, RO groups of one or more RO groups, and (1) a CSI-RS index based on the number of channel status information reference signals (CSI-RS) and an index associated with one or more PRACH transmissions, or (2) an SSB index based on the number of synchronization signal blocks (SSBs) and an index associated with one or more PRACH transmissions.

[0095] (Control signal) In this disclosure, the downlink control signal (information) relating to this disclosure may be a signal (information) transmitted via the PDCCH of the physical layer, or it may be a signal (information) transmitted via the MAC Control Element (CE) of the upper layer or RRC. The downlink control signal may be a predefined signal (information).

[0096] The uplink control signal (information) relating to this disclosure may be a signal (information) transmitted via PUCCH at the physical layer, or a signal (information) transmitted via MAC CE at a higher layer or RRC. Furthermore, the uplink control signal may be a predefined signal (information). The uplink control signal may be Uplink Control Information (UCI), first-stage sidelink control information (SCI), or second-stage SCI.

[0097] (base station) In this disclosure, a base station may be, for example, a transmission reception point (TRP), a cluster head, an access point, a remote radio head (RRH), an eNodeB (eNB), a gNodeB (gNB), a base station (BS), a base transceiver station (BTS), a base unit, or a gateway. In side-link communication, a terminal may be used instead of a base station. A base station may be a relay device that relays communication between a higher-level node and a terminal. A base station may be a roadside unit.

[0098] (Uphill rink / Downhill rink / Side rink) This disclosure may apply to uplinks, downlinks, and sidelinks.

[0099] For example, this disclosure may be applied to uplink channels such as PUSCH, PUCCH, and PRACH, downlink channels such as PDSCH, PDCCH, and PBCH, and sidelinks such as PSSCH (Physical Sidelink Shared Channel), PSCCH (Physical Sidelink Control Channel), and PSBCH (Physical Sidelink Broadcast Channel).

[0100] PDCCH, PDSCH, PUSCH, and PUCCH are examples of downlink control channels, downlink data channels, uplink data channels, and uplink control channels, respectively. PSCCH and PSSCH are examples of sidelink control channels and sidelink data channels, respectively. PBCH and PSBCH are examples of broadcast channels, respectively, and PRACH is an example of a random access channel.

[0101] (Data channel / Control channel) This disclosure may apply to either data channels or control channels. The channels in this disclosure may be replaced with data channels including PDSCH, PUSCH, and PSSCH, and / or control channels including PDCCH, PUCCH, PBCH, PSCCH, and PSBCH.

[0102] (reference signal) In this disclosure, a reference signal is a signal known to both the base station and the mobile station, and each reference signal may be referred to as a reference signal (RS) or pilot signal. A reference signal may be one of the following: Demodulation RS (DMRS), Channel State Information - Reference Signal (CSI-RS), Tracking Reference Signal (TRS), Phase Tracking Reference Signal (PTRS), Cell-specific Reference Signal (CRS), or Sounding Reference Signal (SRS).

[0103] (Time interval) In this disclosure, a time resource unit is not limited to one or a combination of slots and symbols, but may be a frame, superframe, subframe, slot, subslot of a time slot, 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 units. The number of symbols contained in one slot is not limited to the number of symbols exemplified in the embodiments described above, but may be any other number of symbols.

[0104] (Frequency band) This disclosure may apply to either the licensed band or the unlicensed band.

[0105] (communication) This disclosure may apply to any of the following: communication between a base station and a terminal (Uu-link communication), communication between terminals (side-link communication), and vehicle-to-everything (V2X) communication. The channels in this disclosure may be replaced with PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, and PBCH.

[0106] Furthermore, this disclosure may apply to terrestrial networks or non-terrestrial networks (NTNs) that use satellites or high-altitude pseudo-satellites (HAPS). It may also apply to networks with large cell sizes or terrestrial networks with large latency relative to symbol length or slot length, such as ultra-wideband transmission networks.

[0107] (Antenna port) An antenna port refers to a logical antenna (antenna group) formed by one or more physical antennas. That is, an antenna port does not necessarily refer to a single physical antenna, but may also refer to an array antenna formed by multiple antennas. For example, the number of physical antennas forming an antenna port is not defined; instead, an antenna port is defined as the smallest unit on which a terminal can transmit a reference signal. Alternatively, an antenna port can be defined as the smallest unit for multiplying the weights of a precoding vector.

[0108] As described above, embodiments of the present disclosure provide advanced communication systems, communication methods, and communication devices that can advantageously allocate resources for multi-PRACH transmission.

[0109] This disclosure can be implemented by software, by hardware, or by software working in conjunction with hardware. Each functional block used in the description of the embodiments above may be implemented in part or as a large-scale integrated circuit (LSI), and each process described in the embodiments above may be controlled in part or as a combination of LSIs. An LSI may be formed individually as a chip, or as a single chip containing some or all of the functional blocks. An LSI may include data input / output units coupled to itself. Depending on the degree of integration, LSIs may be referred to as ICs, system LSIs, super LSIs, or ultra LSIs. However, the technology for implementing integrated circuits is not limited to LSIs and can be implemented using dedicated circuits, general-purpose processors, or dedicated processors. Furthermore, FPGAs (field-programmable gate arrays) that can be programmed after the manufacture of the LSI, or reconfigurable processors that can reconfigure the connections and settings of circuit cells located inside the LSI, can also be used. This disclosure can be implemented as digital or analog processing. If LSIs are replaced by future integrated circuit technologies as a result of advancements in semiconductor technology or other derivative technologies, functional blocks can be integrated using those future integrated circuit technologies. Biotechnology can also be applied.

[0110] This disclosure can be implemented by any type of device, apparatus, or system having communication capabilities (collectively referred to as communication apparatus).

[0111] Such communication devices are not limited to a few examples and include a variety of combinations of telephones (e.g., mobile phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, netbooks), cameras (e.g., digital still cameras / video cameras), digital players (e.g., digital audio players / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, and vehicles that provide communication capabilities (e.g., automobiles, airplanes, ships).

[0112] Communication devices are not limited to portable or mobile devices, but also include all kinds of non-portable or fixed devices, devices, and systems, such as smart home devices (appliances, lighting equipment, smart meters or measuring instruments, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0113] Communication includes data communication via cellular systems, wireless LAN systems, and communication satellite systems, as well as data communication using combinations of these.

[0114] The communication device may include devices such as controllers and sensors coupled to a communication device that performs the communication functions described in this disclosure. For example, this may include controllers and sensors that generate control signals and data signals used by the communication device that performs the communication functions of the communication device.

[0115] Communication equipment may further include base stations, access points, and any other devices, devices, or systems that communicate with or control infrastructure equipment, such as the devices in the non-limiting examples above.

[0116] While some characteristics of various embodiments are described with reference to the apparatus, it will be understood that the corresponding characteristics also apply to the methods of various embodiments, and vice versa.

[0117] This disclosure may be referenced to the following:

[0118] (Item 1) A circuit that, during operation, determines a group of Random Access Channel Occasions (ROs) containing one or more PRACH transmissions based on the number of PRACH transmissions in multiple physical Random Access Channel (PRACH) transmissions, and determines the preamble to be used for the RO group based on the mapping between one or more preambles and one or more RO groups, During operation, a transmitting unit transmits the preamble, A communication device equipped with the following features.

[0119] One advantage is that it allows for improved use of preambles that are used multiple times in PRACH transmissions.

[0120] (Item 2) The communication device according to claim 1, wherein the circuit is configured to determine one or more RO groups and one or more preambles based on the number of synchronization signal blocks (SSBs) and an index associated with one or more PRACH transmissions, and each of the one or more RO groups is associated with an SSB index of the SSB.

[0121] One advantage is that it allows for improved use of preambles that are used multiple times in PRACH transmissions.

[0122] (See item 3) The mapping is applicable to a time interval, the time interval being a set of association periods between consecutive OFDM symbols, slots, subframes, frames, synchronization signal blocks (SSBs) and random access channel occasions (SSB-ROs), or an SSB-RO association pattern period, and the transmitting unit transmits the preamble in the RO group within the time interval, the communication device according to claim 1.

[0123] It is possible to shorten the transmission period of multi-PRACH transmissions in a single PRACH trial, which has the advantage of reducing initial access delays compared to the case where preamble resources are eventually distributed over a longer period as required by the current technical specifications.

[0124] (Item 4) A communication device according to claim 1, wherein there is one or more PRACH transmissions, and each of the RO groups of the one or more RO groups is associated with one of the one or more PRACH transmissions.

[0125] One advantage is that it allows for improved use of preambles that are used multiple times in PRACH transmissions.

[0126] (Item 5) The communication device according to item 4, wherein the RO group is determined from one or more RO groups based on the SSB index of the number of synchronization signal blocks (SSB).

[0127] One advantage is that it allows for improved use of preambles that are used multiple times in PRACH transmissions.

[0128] (Item 6) The communication device according to claim 1, wherein the one or more preambles are mapped sequentially or cyclically to the one or more RO groups in the mapping.

[0129] The increased flexibility in configuring preambles for multi-PRACH transmission improves the provision of PRACH resources for other purposes.

[0130] (Item 7) A communication device according to claim 1, wherein one of the one or more preambles is mapped to one of the one or more RO groups.

[0131] The increased flexibility in configuring preambles for multi-PRACH transmission improves the provision of PRACH resources for other purposes.

[0132] (Item 8) The communication device according to claim 1, wherein the one or more preambles constitute a first preamble set, the mapping between the first preamble set and the one or more RO groups constitutes a first mapping, and there exists at least a second mapping between at least a second preamble set containing one or more preambles and the one or more RO groups, the at least second preamble set containing one or more preambles being identical or different from the first preamble set, and each preamble set is mapped sequentially or cyclically to the one or more RO groups in the time domain.

[0133] The increased flexibility in configuring preambles for multi-PRACH transmission improves the provision of PRACH resources for other purposes.

[0134] (Item 9) The communication device according to claim 1, wherein the one or more preambles constitute a first preamble set, the mapping between the first preamble set and the one or more RO groups constitutes a first mapping, and there is at least a second mapping between at least a second preamble set containing one or more preambles and the one or more RO groups, and the total number of preambles mapped to the one or more RO groups in the first mapping is different from the total number in the second mapping.

[0135] The increased flexibility in configuring preambles for multi-PRACH transmission improves the provision of PRACH resources for other purposes.

[0136] (Item 10) The communication device according to claim 1, wherein each of the one or more RO groups is mapped to the same preamble or to different preambles.

[0137] The increased flexibility in configuring preambles for multi-PRACH transmission improves the provision of PRACH resources for other purposes.

[0138] (Item 11) The communication device according to claim 1, wherein the total number of one or more preambles in the mapping or the total number of one or more RO groups in the mapping differs based on the number of synchronization signal blocks (SSBs) and the index associated with one or more PRACH transmissions.

[0139] The increased flexibility in configuring preambles for multi-PRACH transmission improves the provision of PRACH resources for other purposes.

[0140] (Item 12) A communication device according to description 8 or 9, wherein each set of the first preamble set and at least the second preamble set is assigned to each of one or more transmit / receive points, or each of one or more cells, or each of one or more beamsets.

[0141] The increased flexibility in configuring preambles for multi-PRACH transmission improves the provision of PRACH resources for other purposes.

[0142] (Item 13) The communication device according to claim 1, wherein the number of preambles in the one or more preambles is different from the number of RO groups in the one or more RO groups, and the one or more remaining RO groups in the one or more RO groups that are not mapped to the one or more preambles are assigned to other transmissions or left unused.

[0143] This has the advantage of overcoming the limitations of a small set of preambles to support, for example, all possible RO groups associated with each SSB index or CSI-RS index.

[0144] (Item 14) The communication device according to claim 1, wherein a first preamble set including one or more preambles is mapped to an RO group set including one or more RO groups, the number of preambles in the first preamble set is less than the number of RO groups in the RO group set, and the circuit is configured to map one or more preambles of a second preamble set to one or more remaining RO groups in the RO group set.

[0145] This has the advantage of overcoming the limitations of a small set of preambles to support, for example, all possible RO groups associated with each SSB index or CSI-RS index.

[0146] (Item 15) The communication device according to description 2, wherein the number of preambles in the one or more preambles is greater than the number of RO groups in the one or more RO groups, and there is one or more preambles that remain unused without being mapped.

[0147] The increased flexibility in configuring preambles for multi-PRACH transmission improves the provision of PRACH resources for other purposes.

[0148] (Item 16) The mapping is in the form of a first table showing one or more preamble sets used in the time domain, and a second table showing RO group sets based on the number of indices and SSBs associated with one or more PRACH transmissions, and the circuit is configured to determine the RO groups and the preambles based on the first table and the second table, the communication device according to claim 1.

[0149] Mapping offers the advantage of improving the flexibility of gNBs.

[0150] (Item 17) The communication device according to description 1, wherein the mapping indicates that in a frequency division multiplexing (FDM) scheme, each preamble in the set of preambles, which includes the one or more preambles, is mapped to two or more RO groups.

[0151] This has the advantage of reducing the amount of PRACH preamble required.

[0152] (Item 18) The communication device according to claim 1, wherein the mapping is further a mapping between the preamble, the RO group, and the SSB index.

[0153] Mapping ensures that preambles are transmitted within the RO group using the same SSB beam. This gives the gNB the advantage of being able to perform composite detection of preambles and obtain a composite gain.

[0154] (Item 19) The communication device according to description 18, wherein the mapping is an explicit notification from one or a combination of Master Information Blocks (MIBs), System Information Blocks (SIBs), Upper Layer Parameters, and Downlink Control Information (DCIs).

[0155] Mapping offers the advantage of increased flexibility when gNB configures multi-PRACH tables.

[0156] (Item 20) The communication device according to claim 18, wherein the preamble is further mapped to two or more RO groups in a frequency division multiplexing (FDM) scheme.

[0157] This has the advantage of reducing the amount of PRACH preamble required.

[0158] (Item 21) The communication device according to description 2, wherein in the index, 1 represents 2, 4, or 8 PRACH transmissions, 2 represents 2 and 4, 2 and 8, or 4 and 8 PRACH transmissions, and 3 represents 2, 4, and 8 PRACH transmissions.

[0159] It is possible to shorten the transmission period of multi-PRACH transmissions in a single PRACH trial, which has the advantage of reducing initial access delays compared to the case where preamble resources are eventually distributed over a longer period as required by the current technical specifications.

[0160] (Item 22) The communication device according to claim 1, wherein the RO group includes a plurality of sub-RO groups, and the mapping is further a mapping between the preamble, the sub-RO groups of the one or more RO groups, and the synchronous signal block (SSB) index.

[0161] Mapping offers the advantage of increased flexibility when gNB configures multi-PRACH tables.

[0162] (Item 23) The mapping further comprises a mapping between the preamble, an RO group from the one or more RO groups, and a channel state information reference signal (CSI-RS) index, wherein the CSI-RS index is based on the number of CSI-RSs and an index associated with one or more PRACH transmissions, according to the communication device described in 1.

[0163] This has the advantage of applying the mapping when the SSB index cannot be applied and the CSI-RS index is used instead.

[0164] (Item 24) A circuit that, during operation, determines a mapping between one or more preambles and one or more Random Access Channel Occasion (RO) groups based on an index associated with one or more multiple physical Random Access Channel (PRACH) transmissions, During operation, a transmitting unit signals the mapping to a communication device, A base station equipped with the necessary equipment.

[0165] One advantage is that it allows for improved use of preambles that are used multiple times in PRACH transmissions.

[0166] (Item 25) The base station according to claim 24, wherein the mapping is further a mapping between a preamble from one or more preambles, an RO group from one or more RO groups, and (1) a CSI-RS index based on the number of channel state information reference signals (CSI-RS) and an index associated with one or more PRACH transmissions, or (2) an SSB index based on the number of synchronization signal blocks (SSB) and an index associated with one or more PRACH transmissions.

[0167] Mapping offers the advantage of increased flexibility when configuring multi-PRACH tables when the gNB is SSB or CSI-RS.

[0168] (Item 26) Based on the number of PRACH transmissions in multiple physical random access channel (PRACH) transmissions, a group of ROs containing one or more random access channel occasions (ROs) is determined. Based on the mapping between one or more preambles and one or more RO groups, the preamble to be used for the RO group is determined. The RO group transmits the preamble. Communication method.

[0169] One advantage is that it allows for improved use of preambles that are used multiple times in PRACH transmissions.

[0170] Those skilled in the art will understand that numerous changes and / or modifications can be made to this disclosure without departing from the embodiments specifically shown herein. Accordingly, these embodiments are illustrative in all respects and should not be construed as limiting.

Claims

1. A circuit that, during operation, determines a group of Random Access Channel Occasions (ROs) containing one or more PRACH transmissions based on the number of PRACH transmissions in multiple physical Random Access Channel (PRACH) transmissions, and determines the preamble to be used for the RO group based on the mapping between one or more preambles and one or more RO groups, During operation, a transmitting unit transmits the preamble, A communication device equipped with the following features.

2. The circuit is configured to determine one or more RO groups and one or more preambles based on the number of synchronization signal blocks (SSBs) and an index associated with one or more PRACH transmissions, and each of the one or more RO groups is associated with the SSB index of the SSB. The communication device according to claim 1.

3. The mapping is applicable to time intervals, the time interval being a set of association periods between consecutive OFDM symbols, slots, subframes, frames, synchronization signal blocks (SSBs) and random access channel occasions (SSB-ROs), or SSB-RO association pattern periods, and the transmitter transmits the preamble in the RO group within the time interval. The communication device according to claim 1.

4. The RO group is determined from one or more RO groups based on the SSB index of the number of synchronization signal blocks (SSBs). The communication device according to claim 1.

5. One of the one or more preambles is mapped to one of the one or more RO groups. The communication device according to claim 1.

6. The one or more preambles constitute a first preamble set, the mapping between the first preamble set and the one or more RO groups constitutes a first mapping, and there exists at least a second mapping between at least a second preamble set containing one or more preambles and the one or more RO groups, the at least second preamble set containing one or more preambles being identical or different from the first preamble set, and each preamble set is mapped sequentially or cyclically to the one or more RO groups in the time domain. The communication device according to claim 1.

7. Each of the one or more RO groups is mapped to the same preamble or to different preambles. The communication device according to claim 1.

8. The total number of preambles or RO groups in the mapping differs based on the number of synchronization signal blocks (SSBs) and the index associated with one or more PRACH transmissions. The communication device according to claim 1.

9. Each of the first preamble set and each of the at least second preamble sets is assigned to each of one or more transmit / receive points, or each of one or more cells, or each of one or more beamsets. The communication device according to claim 6.

10. The mapping is in the form of a first table showing one or more preamble sets used in the time domain, and a second table showing RO group sets based on the number of indices and SSBs associated with one or more PRACH transmissions, wherein the circuit is configured to determine the RO groups and the preambles based on the first and second tables. The communication device according to claim 1.

11. The mapping is further a mapping between the preamble, the RO group, and the SSB index. The communication device according to claim 1.

12. The mapping further comprises a mapping between the preamble, an RO group from the one or more RO groups, and a channel state information reference signal (CSI-RS) index, wherein the CSI-RS index is based on the number of CSI-RSs and an index associated with one or more PRACH transmissions. The communication device according to claim 1.

13. A circuit that, during operation, determines a mapping between one or more preambles and one or more Random Access Channel Occasion (RO) groups based on an index associated with one or more physical Random Access Channel (PRACH) transmissions, During operation, a transmitting unit signals the mapping to a communication device, A base station equipped with the necessary equipment.

14. The mapping further comprises a preamble from one or more preambles, an RO group from one or more RO groups, and a mapping between (1) a CSI-RS index based on the number of channel state information reference signals (CSI-RS) and an index associated with one or more PRACH transmissions, or (2) an SSB index based on the number of synchronization signal blocks (SSB) and an index associated with one or more PRACH transmissions. The base station according to claim 13.

15. Based on the number of PRACH transmissions in multiple physical random access channel (PRACH) transmissions, an RO group containing one or more Random Access Channel Occasions (ROs) is determined. Based on the mapping between one or more preambles and one or more RO groups, the preamble to be used for the RO group is determined. The RO group transmits the preamble. Communication method.

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