Multi-prach transmission in cross-division duplexing

Abstract

The present disclosure provides a communication apparatus and method for multiple Physical Random Access Channel (multi-PRACH) transmission in Cross-Division Duplexing (XDD), the apparatus comprising: circuitry, which in operation, determines a random access channel occasion (RO) group from a plurality of RO groups for multiple PRACH transmissions, each of the plurality of RO groups including one or more ROs; and a transmitter, which in operation, transmits a preamble on the one or more ROs of the determined RO group, wherein the one or more ROs include at least one RO in subband non-overlapping full duplex (SBFD) symbols or at least one RO in non-SBFD symbols.

Description

DESCRIPTIONTitle Of Invention: MULTI-PRACH TRANSMISSION IN CROSS-DIVISION DUPLEXINGTECHNICAL FIELD[1] The following disclosure relates to a communication apparatus and a communication method, and more particularly, for multiple Physical Random Access Channel (multi-PRACH) transmission in Cross-Division Duplexing (XDD).BACKGROUND[2] In Release (Rel.) 18, NR duplex operation (e.g., cross division duplex (XDD)) has been studied, for example in technical report (TR) 38.858 One of the main topics of discussion in Rel. 18 is to study how to enable subband non-overlapping full duplex (SBFD) within a legacy time division duplexing (TDD) band, which allows simultaneous existence of downlink (DL) and uplink (UL) within the legacy TDD band, where a subband is used to split transmission directions. For XDD operation, a SBFD symbol is defined as a OFDM symbol with UL subband(s) that a gNB may use for a UL transmission A SBFD symbol may be a legacy DL symbol and / or a legacy flexible symbol. A non-SBFD symbol may be a legacy UL symbol. Subband non-overlapping full duplex (SBFD) may be referred as subband full duplex. A working item of Rel. 19 XDD has also been approved recently, wherein one of the objectives is to specify XDD operation to support random access in Radio Resource Control (RRC) CONNECTED mode and RRC IDLE / INACTIVE mode [RP-234035][3] Based on simulation results of a technical report for study on NR coverage enhancements in Rel. 17 [TR 38.830], Physical Random Access Channel (PRACH) was identified as a coverage bottleneck channel. As a remedy, in Rel. 18, multi-PRACH transmission with same beam has been specified in non-SBFD symbols only to enhance coverage. However, there is at present no solution to realize multi-PRACH transmission for a SBFD capable UE that can enjoy the benefits of introduction of SBFD symbols in XDD operation to improve coverage of PRACH.[4] There is thus a need for a communication apparatus and a communication method for multi-PRACH transmission in XDD to solve the above-mentioned issues. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.SUMMARY|5| Non-limiting and exemplary embodiments facilitate providing communication apparatuses and communication methods for multi-PRACH transmission in XDD.[6] In a first aspect, the present disclosure provides a communication apparatus comprising: circuitry, which in operation, determines a random access channel occasion (RO) (also known as Physical Random Access Channel occasion) group from a plurality of RO groups for multiple Physical Random Access Channel (PRACH) transmissions, each of the plurality of RO groups including one or more ROs; and a transmitter, which in operation, transmits a preamble on the one or more ROs of the determined RO group, wherein the one or more ROs include at least one RO in subband non-overlapping full duplex (SBFD) symbols or at least one RO in non-SBFD symbols.[7] In a second aspect, the present disclosure provides a communication device comprising: a transmitter, which in operation, transmits control information relating to a RO group of a plurality of RO groups used for multiple PRACH transmissions, each of the plurality of RO groups including one or more ROs; and a receiver, which in operation, receives a preamble on the one or more ROs of the RO group, wherein the one or more ROs include at least one RO in SBFD symbols or at least one RO in non-SBFD symbols|8| In a third aspect, the present disclosure provides a communication method implemented by a communication apparatus, comprising: determining a RO group from a plurality of RO groups for multiple PRACH transmissions, each of the plurality of RO groups including one or more ROs; and transmitting a preamble on the one or more ROs of thedetermined RO group, wherein the one or more ROs include at least one RO in SBFD symbols or at least one RO in non-SBFD symbols.[9] In a fourth aspect, the present disclosure provides a communication method implemented by a communication device, comprising: transmitting control information relating to a RO group of a plurality of RO groups used for multiple PRACH transmissions, each of the plurality of RO groups including one or more ROs; and receiving a preamble on the one or more ROs of the RO group, wherein the one or more ROs include at least one RO in SBFD symbols or at least one RO in non-SBFD symbols.

[0010] Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. The benefits and / or advantages may be individually obtained by the various embodiments and features of the specification and drawings, which need not all be provided in order to obtain one or more of such benefits and / or advantages.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to illustrate various embodiments and to explain various principles and advantages in accordance with present embodiments.

[0012] Figure 1 shows an exemplary the 3rd Generation Partnership Project (3GPP) next generation radio access network (NG-RAN) architecture to which exemplary embodiments of the present disclosure may be applied.

[0013] Figure 2 depicts a schematic drawing which shows functional split between NG-RAN and 5GC to which exemplary embodiments of the present disclosure may be applied.

[0014] Figure 3 depicts a sequence diagram for radio resource control (RRC) connection setup / reconfiguration procedures to which exemplary embodiments of the present disclosure may be applied.

[0015] Figure 4 depicts a schematic drawing showing usage scenarios of Enhanced mobile broadband (eMBB), Massive Machine Type Communications (mMTC) and Ultra Reliable and Low Latency Communications (URLLC) to which exemplary embodiments of the present disclosure may be applied.116| Figure 5 shows a block diagram showing an exemplary 5G system architecture for Vehicle-to-everything (V2X) communication in a non-roaming scenario.

[0017] Figure 6 shows a diagram illustrating a comparison between the legacy (Rel. 15 / 16 / 17) TDD and Rel. 18 / 19 XDD.

[0018] Figure 7 shows a schematic diagram illustrating an example configuration of a communication apparatus for multi-PRACH transmission in XDD in accordance with various embodiments of the present disclosure.

[0019] Figure 8 shows a flowchart illustrating a method for multi-PRACH transmission in XDD according to various embodiments of the present disclosure.

[0020] Figure 9 shows a flowchart illustrating another method for a multi-PRACH transmission in XDD according to various embodiments of the present disclosure.

[0021] Figure 10 shows an example of a multi-PRACH transmission with RO(s) in SBFD symbols and shared RO(s) in non-SBFD symbols|22| Figure 11 shows an example of a multi-PRACH transmission with RO(s) in SBFD symbols and separated RO(s) in non-SBFD symbols.

[0023] Figure 12 shows an example of a multi-PRACH transmission with a time configuration K2for a SBFD capable UE and a time configuration K for a legacy UE.

[0024] Figure 13 shows an example of how 8 groups of ROs for 2 PRACHs are determined based on an existing method in non-SBFD symbols in a periodicity of K±.1251 Figure 14 shows an example of how ROs in non-SBFD symbols are not counted when determining groups of ROs based on the existing method.

[0026] Figure 15 shows an example of how ROs in SBFD symbols are not counted when determining groups of ROs based on the existing method.

[0027] Figure 16 shows an example of how groups of ROs for 2 PRACHs are determined based on a virtual RO as a starting point.

[0028] Figure 17 shows an example of how groups of ROs for 2 PRACHs are determined based on applying a 2-layer searching procedure on each UL subband in a time configuration K2.

[0029] Figure 18 shows a diagram illustrating an example of a detailed RRC setup procedure between a UE and a gNB for enabling multi-PRACH transmission in XDD according to an embodiment of the present disclosure.

[0030] Figure 19 shows a flowchart illustrating a communication method implemented by a UE for enabling a multi-PRACH transmission in XDD according to various embodiments of the present disclosure.

[0031] Figure 20 shows a flowchart illustrating a communication method implemented by a gNB for enabling a multi-PRACH transmission in XDD according to various embodiments of the present disclosure.

[0032] A person skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been depicted to scale. For example, the dimensions of some of the elements in the illustrations, block diagrams or flowcharts may beexaggerated in respect to other elements to help an accurate understanding of the present embodiments.DETAILED DESCRIPTION

[0033] Some embodiments of the present disclosure will be described, by way of example only, with reference to the drawings. Like reference numerals and characters in the drawings refer to like elements or equivalents.

[0034] 3GPP has been working at the next release for the 5111generation cellular technology, simply called 5G, including the development of a new radio access technology (NR) operating in frequencies ranging up to 100 GHz. The first version of the 5G standard was completed at the end of 2017, which allows proceeding to 5G NR standard-compliant trials and commercial deployments of smartphones.

[0035] The second version of the 5G standard was completed in June 2020, which further expand the reach of 5Gto new services, spectrum and deployment such as unlicensed spectrum (NR-U), non-public network (NPN), time sensitive networking (TSN) and cellular-V2X.

[0036] Among other things, the overall system architecture assumes an NG-RAN (Next Generation - Radio Access Network) that comprises gNBs, providing the NG-radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocol terminations towards the UE. The gNBs are interconnected with each other by means of the Xn interface. The gNBs are also connected by means of the Next Generation (NG) interface to the NGC (Next Generation Core), more specifically to the AMF (Access and Mobility Management Function) (e g., a particular core entity performing the AMF) by means of the NG-C interface and to the UPF (User Plane Function) (e.g., a particular core entity performing the UPF) by means of the NG-U interface. The NG-RAN architecture is illustrated in Figure 1 (see e.g., 3GPP TS 38.300 V16.3.0).

[0037] The user plane protocol stack for NR (see e g., 3GPP TS 38.300, section 4.4.1) comprises the PDCP (Packet Data Convergence Protocol, see section 6.4 of TS 38.300), RLC(Radio Link Control, see section 6.3 of TS 38.300) and MAC (Medium Access Control, see section 6.2 of TS 38.300) sublayers, which are terminated in the gNB on the network side. Additionally, a new access stratum (AS) sublayer (SDAP, Service Data Adaptation Protocol) is introduced above PDCP (see e.g., sub-clause 6.5 of 3GPP TS 38.300). A control plane protocol stack is also defined for NR (see for instance TS 38.300, section 4.4.2). An overview of the Layer 2 functions is given in sub-clause 6 of TS 38 300. The functions of the PDCP, RLC and MAC sublayers are listed respectively in sections 6.4, 6.3, and 6.2 of TS 38.300. The functions of the RRC layer are listed in sub-clause 7 of TS 38.300.1381 For instance, the Medium-Access-Control layer handles logical -channel multiplexing, and scheduling and scheduling-related functions, including handling of different numerologies.

[0039] The physical layer (PHY) is for example responsible for coding, PHY hybrid automatic repeat request (HARQ) processing, modulation, multi-antenna processing, and mapping of the signal to the appropriate physical time-frequency resources. It also handles mapping of transport channels to physical channels. The physical layer provides services to the MAC layer in the form of transport channels. A physical channel corresponds to the set of timefrequency resources used for transmission of a particular transport channel, and each transport channel is mapped to a corresponding physical channel. For instance, the physical channels are PRACH (Physical Random Access Channel), PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel) for uplink, PDSCH (Physical Downlink Shared Channel), PDCCH (Physical Downlink Control Channel) and PBCH (Physical Broadcast Channel) for downlink, and PSSCH (Physical Sidelink Shared Channel), PSCCH (Physical Sidelink Control Channel) and Physical Sidelink Feedback Channel (PSFCH) for sidelink (SL).

[0040] SL supports UE-to-UE direct communication using the SL resource allocation modes, physical layer signals / channels, and physical layer procedures. Two new radio (NR) SL resource allocation modes are supported: (a) mode 1, where the NR SL resource allocation is provided by the network; and (b) mode 2, where UE decides NR SL transmission resource in the resource pool(s). Two SL resource allocations modes are applicable to LTE V2X: (a) mode 3, where the LTE SL resource allocation is scheduled by eNB primarily for transmission of periodically occurring messages; and (b) mode 4, where the UE decides autonomously the LTE SL transmission resource in the resource pool(s).

[0041] PSCCH indicates resource and other transmission parameters used by a UE for PSSCH. PSCCH transmission is associated with a demodulation reference signal (DMRS). PSSCH transmits the transport blocks (TBs) of data themselves, and control infonnation for HARQ procedure and channel state information (CSI) feedback triggers, etc. At least 6 Orthogonal Frequency Division Multiplexing (OFDM) symbols within a slot are used for PSSCH transmission. PSSCH transmission is associated with a DMRS and may be associated with a phase-tracking reference signal (PT-RS).1421 PSFCH carries HARQ feedback over the SL from a UE which is an intended recipient of a PSSCH transmission to the UE which performed the transmission. PSFCH sequence is transmitted in one PRB repeated over two OFDM symbols near the end of the SL resource in a slot.

[0043] The SL synchronization signal consists of SL primary and SL secondary synchronization signals (S-PSS, S-SSS), each occupying 2 symbols and 127 subcarriers. Physical Sidelink Broadcast Channel (PSBCH) occupies 9 and 5 symbols for normal and extended cyclic prefix cases respectively, including the associated demodulation reference signal (DM-RS).

[0044] Regarding physical layer procedure for HARQ feedback for sidelink, SL HARQ feedback uses PSFCH and can be operated in one of two options. In one option, which can be configured for unicast and groupcast, PSFCH transmits either ACK or NACK using a resource dedicated to a single PSFCH transmitting UE. In another option, which can be configured for groupcast, PSFCH transmits NACK, or no PSFCH signal is transmitted, on a resource that can be shared by multiple PSFCH transmitting UEs.

[0045] In SL resource allocation mode 1, a UE which received PSFCH can report SL HARQ feedback to gNB via PUCCH or PUSCH.

[0046] Regarding physical layer procedure for power control for sidelink, for in-coverage operation, the power spectral density of the SL transmissions can be adjusted based on thepathloss from the gNB, whereas for unicast, the power spectral density of some SL transmissions can be adjusted based on the pathloss between the two communicating UEs.

[0047] Regarding physical layer procedure for CSI report, for unicast, channel state information reference signal (CSI-RS) is supported for CSI measurement and reporting in sidelink. A CSI report is carried in a SL MAC CE148] For measurement on the sidelink, the following UE measurement quantities are supported:• PSBCH reference signal received power (PSBCH RSRP);• PSSCH reference signal received power (PSSCH-RSRP);• PSCCH reference signal received power (PSCCH-RSRP);• Sidelink received signal strength indicator (SL RS SI);• Sidelink channel occupancy ratio (SL CR);• Sidelink channel busy ratio (SL CBR).

[0049] For XDD operation, the frequency domain (or frequency resource or frequency bandwidth) is divided into a plurality of frequency domains (also referred to as, for example, sub-bands, RB sets, sub-bandwidths, or sub-BWPs (Bandwidth parts)). The terminal performs transmission and reception in a direction (for example, a downlink or uplink direction) in units of subbands that are the divided domains. For SBFD symbols, the terminal may perform transmission / reception in one direction of uplink and downlink directions, and may not perform transmission / reception in the other direction The base station, on the other hand, may be capable of performing both uplink and downlink transmissions / receptions simultaneously. SBFD symbols may have a fewer frequency domain usable for downlink compared to symbols for which only downlink transmission / reception is performed. Further, SBFD symbols may have a fewer frequency domain usable for uplink compared to symbol for which only uplink transmission / reception is performed.

[0050] Further, for SBFD symbols, the terminal may perform uplink and downlink transmissions / receptions simultaneously. At this time, the frequency domain transmitted by the terminal and the frequency domain received by the terminal may not be adjacent and a frequency interval (also referred to as a frequency gap) may be provided therebetween.

[0051] Further, sidelink transmi ssion / recepti on may also be included as a transmission / reception direction in units of sub-bands which are the divided domains.

[0052] Use cases / deployment scenarios for NR could include enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), massive machine type communication (mMTC), which have diverse requirements in terms of data rates, latency, and coverage. For example, eMBB is expected to support peak data rates (20Gbps for downlink and lOGbps for uplink) and user-experienced data rates in the order of three times what is offered by IMF-Advanced. On the other hand, in case of URLLC, the tighter requirements are put on ultra-low latency (0.5ms for UL and DL each for user plane latency) and high reliability (1-10-5 within 1ms). Finally, mMTC may preferably require high connection density (1,000,000 devices / km2 in an urban environment), large coverage in harsh environments, and extremely long-life battery for low cost devices (15 years).

[0053] Therefore, the OFDM numerology (e.g., subcarrier spacing, OFDM symbol duration, cyclic prefix (CP) duration, number of symbols per scheduling interval) that is suitable for one use case might not work well for another. For example, low-latency services may preferably require a shorter symbol duration (and thus larger subcarrier spacing) and / or fewer symbols per scheduling interval (also known as transmission time interval (TTI)) than an mMTC service. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP duration than scenarios with short delay spreads. The subcarrier spacing should be optimized accordingly to retain the similar CP overhead. NR may support more than one value of subcarrier spacing. Correspondingly, subcarrier spacing of 15kHz, 30kHz, 60 kHz... are being considered at the moment. The symbol duration Tu and the subcarrier spacing Af are directly related through the formula Af = 1 / Tu. In a similar manner as in LTE systems, the term “resource element” can be used to denote a minimum resource unit being composed of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0054] In the new radio system 5G-NR for each numerology and carrier a resource grid of subcarriers and OFDM symbols is defined respectively for uplink and downlink. Each element in the resource grid is called a resource element and is identified based on the frequency indexin the frequency domain and the symbol position in the time domain (see 3GPP TS 38 21 1 V16.3.0).

[0055] Figure 2 illustrates functional split between NG-RAN and 5GC to which exemplary embodiments of the present disclosure may be applied. NG-RAN logical node is a gNB or ng- eNB. The 5GC has logical nodes AMF, UPF and SMF

[0056] In particular, the gNB and / or ng-eNB host the following main functions:- Functions for Radio Resource Management such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (scheduling);- IP header compression, encryption and integrity protection of data;- Selection of an AMF at UE attachment when no routing to an AMF can be determined from the information provided by the UE;- Routing of User Plane data towards UPF(s);- Routing of Control Plane information towards AMF;- Connection setup and release;- Scheduling and transmission of paging messages;- Scheduling and transmission of system broadcast information (originated from the AMF or OAM);- Measurement and measurement reporting configuration for mobility and scheduling;- Transport level packet marking in the uplink;- Session Management;- Support of Network Slicing;- QoS Flow management and mapping to data radio bearers;- Support of UEs in RRC IN ACTIVE state;- Distribution function for NAS messages;- Radio access network sharing;- Dual Connectivity;- Tight interworking between NR and E-UTRA.

[0057] The Access and Mobility Management Function (AMF) hosts the following main functions:- Non-Access Stratum, NAS, signaling termination;- NAS signaling security;- Access Stratum, AS, Security control;- Inter Core Network, CN, node signaling for mobility between 3GPP access networks;- Idle mode UE Reachability (including control and execution of paging retransmission);- Registration Area management;- Support of intra-system and inter-system mobility;- Access Authentication;- Access Authorization including check of roaming rights;- Mobility management control (subscription and policies);- Support of Network Slicing;- Session Management Function, SMF, selection.

[0058] Furthermore, the User Plane Function, UPF, hosts the following main functions:- Anchor point for Intra- / Inter-RAT mobility (when applicable);- External PDU session point of interconnect to Data Network;- Packet routing & forwarding;- Packet inspection and User plane part of Policy rule enforcement;- Traffic usage reporting;- Uplink classifier to support routing traffic flows to a data network;- Branching point to support multi -homed PDU session;- QoS handling for user plane, e.g., packet filtering, gating, UL / DL rate enforcement;- Uplink Traffic verification (SDF to QoS flow mapping);- Downlink packet buffering and downlink data notification triggering.

[0059] Finally, the Session Management function, SMF, hosts the following main functions:- Session Management;- UE IP address allocation and management;- Selection and control of UP function;- Configures traffic steering at User Plane Function, UPF, to route traffic to proper destination;- Control part of policy enforcement and QoS;- Downlink Data Notification.

[0060] Figure 3 illustrates some interactions between a UE, gNB, and AMF (an 5GC entity) in the context of a transition of the UE from RRC IDLE to RRC CONNECTED for the NAS part (see TS 38.300 V16.3.0). The transition steps are as follows:1. The UE requests to setup a new connection from RRC IDLE.2 / 2a. The gNB completes the RRC setup procedure.NOTE: The scenario where the gNB rejects the request is described below.3. The first NAS message from the UE, piggybacked in RRC SetupC ample te, is sent to AMF.4 / 4a / 5 / 5a. Additional NAS messages may be exchanged between UE and AMF, see TS 23.502 .6. The AMF prepares the UE context data (including PDU session context, the Security Key, UE Radio Capability and UE Security Capabilities, etc.) and sends it to the gNB.7 / 7a. The gNB activates the AS security with the UE.8 / 8a. The gNB performs the reconfiguration to setup SRB2 and DRBs.9. The gNB informs the AMF that the setup procedure is completed.

[0061] RRC is a higher layer signaling (protocol) used for UE and gNB configuration. In particular, this transition involves that the AMF prepares the UE context data (including e g., PDU session context, the Security Key, UE Radio Capability and UE Security Capabilities, etc.) and sends it to the gNB with the INITIAL CONTEXT SETUP REQUEST. Then, the gNB activates the AS security with the UE, which is performed by the gNB transmitting to the UE a SecurityModeCommand message and by the UE responding to the gNB with the SecurityModeComplete message. Afterwards, the gNB performs the reconfiguration to setup the Signaling Radio Bearer 2, SRB2, and Data Radio Bearer(s), DRB(s) by means of transmitting to the UE the RR Reconfiguration message and, in response, receiving by the gNB the RRCReconfigurationComplete from the UE. For a signaling-only connection, the steps relating to the RRCReconfiguration are skipped since SRB2 and DRBs are not setup. Finally, the gNB informs the AMF that the setup procedure is completed with the INITIAL CONTEXT SETUP RESPONSE.

[0062] Figure 4 illustrates some of the use cases for 5G NR. Tn 3rd generation partnership project new radio (3GPP NR), three use cases are being considered that have been envisaged to support a wide variety of services and applications by IMT-2020. The specification for the phase 1 of enhanced mobile-broadband (eMBB) has been concluded. In addition to further extending the eMBB support, the current and future work would involve the standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications. Figure 4 illustrates some examples of envisioned usage scenarios for IMT for 2020 and beyond (see e.g., ITU-R M.2083 Figure 2).|63| The URLLC use case has stringent requirements for capabilities such as throughput, latency and availability and has been envisioned as one of the enablers for future vertical applications such as wireless control of industrial manufacturing or production processes, remote medical surgery, distribution automation in a smart grid, transportation safety, etc Ultra-reliability for URLLC is to be supported by identifying the techniques 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). The general URLLC requirement for one transmission of a packet is a BLER (block error rate) of IE-5 for a packet size of 32 bytes with a user plane latency of 1ms.

[0064] From the physical layer perspective, reliability can be improved in a number of possible ways. The current scope for improving the reliability involves defining separate CQI tables for URLLC, more compact Downlink Control Information (DC1) formats, repetition of PDCCH, etc. However, the scope may widen for achieving ultra-reliability as the NR becomes more stable and developed (for NR URLLC key requirements). Particular use cases of NR URLLC in Rel. 15 include Augmented Reality / Virtual Reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0065] Moreover, technology enhancements targeted by NR URLLC aim at latency improvement and reliability improvement. Technology enhancements for latency improvement include configurable numerology, non-slot-based scheduling with flexible mapping, grant free (configured grant) uplink, slot-level repetition for data channels, and downlink pre-emption. Pre-emption means that a transmission for which resources have already been allocated is stopped, and the already allocated resources are used for another transmission that has beenrequested later, but has lower latency / higher priority requirements. Accordingly, the already granted transmission is pre-empted by a later transmission. Pre-emption is applicable independent of the particular service type. For example, a transmission for a service-type A (URLLC) may be pre-empted by a transmission for a service type B (such as eMBB). Technology enhancements with respect to reliability improvement include dedicated CQI / MCS tables for the target BLER of IE-5.

[0066] The use case of mMTC (massive machine type communication) is characterized by a very large number of connected devices typically transmitting a relatively low volume of nondelay sensitive data. Devices are required to be low cost and to have a very long battery life. From NR perspective, utilizing very narrow bandwidth parts is one possible solution to have power saving from UE perspective and enable long battery life.

[0067] As mentioned above, it is expected that the scope of reliability in NR becomes wider. One key requirement to all the cases, and especially necessary for URLLC and mMTC, is high reliability or ultra-reliability. Several mechanisms can be considered to improve the reliability from radio perspective and network perspective. In general, there are a few key potential areas that can help improve the reliability Among these areas are compact control channel information, data / control channel repetition, and diversity with respect to frequency, time and / or the spatial domain. These areas are applicable to reliability in general, regardless of particular communication scenarios.

[0068] F or NR URLLC, further use cases with tighter requirements have been identified such as factory automation, transport industry and electrical power distribution, including factory automation, transport industry, and electrical power distribution. The tighter requirements are higher reliability (up to 10-6 level), higher availability, packet sizes of up to 256 bytes, time synchronization down to the order of a few ps where the value can be one or a few ps depending on frequency range and short latency in the order of 0.5 to 1 ms in particular a target user plane latency of 0.5 ms, depending on the use cases.

[0069] Moreover, for NR URLLC, several technology enhancements from the physical layer perspective have been identified. Among these are PDCCH (Physical Downlink Control Channel) enhancements related to compact DCI, PDCCH repetition, increased PDCCHmonitoring. Moreover, UCT (Uplink Control Information) enhancements are related to enhanced HARQ (Hybrid Automatic Repeat Request) and CSI feedback enhancements. Also, PUSCH enhancements related to mini-slot level hopping and retransmission / repetition enhancements have been identified. The term “mini-slot” refers to a Transmission Time Interval (TTI) including a smaller number of symbols than a slot (a slot comprising fourteen symbols).170J The 5G QoS (Quality of Service) model is based on QoS flows and supports both QoS flows that require guaranteed flow bit rate (GBR QoS flows) and QoS flows that do not require guaranteed flow bit rate (non-GBR QoS Flows). At NAS level, the QoS flow is thus the finest granularity of QoS differentiation in a PDU session. A QoS flow is identified within a PDU session by a QoS flow ID (QFI) carried in an encapsulation header over NG-U interface.

[0071] For each UE, 5GC establishes one or more PDU Sessions. For each UE, the NG-RAN establishes at least one Data Radio Bearers (DRB) together with the PDU Session, and additional DRB(s) for QoS flow(s) of that PDU session can be subsequently configured (it is up to NG-RAN when to do so), e.g., as shown above with reference to Figure 3. The NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS level packet filters in the UE and in the 5GC associate UL and DL packets with QoS Flows, whereas AS-level mapping rules in the UE and in the NG-RAN associate UL and DL QoS Flows with DRBs.

[0072] Figure 5 illustrates a 5G NR non-roaming reference architecture (see TS 23.287 V16.4.0, section 4.2. 1.1). An Application Function (AF), e g., an external application server hosting 5G services, exemplarily described in Figure 4, interacts with the 3GPP Core Network in order to provide services, for example to support application influence on traffic routing, accessing Network Exposure Function (NEF) or interacting with the Policy framework for policy control (see Policy Control Function, PCF), e g., QoS control. Based on operator deployment, Application Functions considered to be trusted by the operator can be allowed to interact directly with relevant Network Functions. Application Functions not allowed by the operator to access directly the Network Functions use the external exposure framework via the NEF to interact with relevant Network Functions.

[0073] Figure 5 shows further functional units of the 5G architecture for V2X communication, namely, 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 the 5GC, as well as with V2X Application Server (V2AS) and Data Network (DN), e g., operator services, Internet access or 3rd party services. All or a part of the core network functions and the application services may be deployed and running on cloud computing environments.|74| In the present disclosure, thus, an application server (for example, AF of the 5G architecture), is provided that comprises a transmitter, which, in operation, transmits a request containing a QoS requirement for at least one of URLLC, eMBB and mMTC services to at least one of functions (for example NEF, AMF, SMF, PCF, UPF, etc) of the 5GC to establish a PDU session including a radio bearer between a gNodeB and a UE in accordance with the QoS requirement and control circuitry, which, in operation, performs the services using the established PDU session.

[0075] In various embodiments below, the phrase “multi-PRACH transmission” may refer to “multiple PRACH transmission”, “repetitions of PRACH transmission”, “N PRACHs” or “A PRACH transmissions” where N is equal to or greater than one

[0076] As mentioned above, one of the main topics of discussion in Rel. 18 is to study how to enable subband non-overlapping full duplex (SBFD) within a legacy time division duplexing (TDD) band, which allows simultaneous existence of downlink (DL) and uplink (UL) within the legacy TDD band, where a subband is used to split transmission directions. For gNB side, (quasi) full duplex is done, while half-duplex can be used for UE side.

[0077] Referring to Figure 6, a subband may include 1 RB or a set of consecutive RBs (e.g., subbands #1 -#3 in subbands 606 in Figure 6), and may be of a semi-static configuration within a period (it was agreed as a baseline under the 3GPP technical report (TR) 38.858). For XDD operation, a SBFD symbol is defined as a OFDM symbol with UL subbands that a g B may use for a UL transmission. A SBFD symbol may be a legacy DL symbol and / or a legacy flexiblesymbol (configured by Tl) -UL- L-ConfigCommon). A non-SBFD symbol may be a legacy UL symbol. It is denoted that a SBFD capable UE (e.g., a SBFD-aware UE) can be a new type of UE that recognizes and is able to handle SBFD symbols and non-SBFD symbols, while a legacy UE is a non-SBFD capable UE (e g., a non- SBFD-aware UE) that recognizes and is able to handle only non-SBFD symbols. For example, Figure 6 shows a comparison of legacy (Rel. 15 / 16 / 17) time division duplexing (TDD) under reference 602 and Rel. 18 / 19 XDD under reference 604. The legacy (Rel. 15 / 16 / 17) TDD under reference 602 comprises only non-SBFD symbols while the Rel. 18 / 19 XDD under reference 604 comprises both SBFD symbols (e g., SBFD symbols 608) and non-SBFD symbols (e.g., non-SBFD symbols 610). It will be appreciated that, in Figure 6, D stands for downlink, U stands for uplink, and F stands for flexible , n may be an integer equal to or greater than 0.

[0078] As also mentioned above, based on simulation results of a technical report for study on NR coverage enhancements in Rel. 17 [TR 38.830], PRACH was identified as a coverage bottleneck channel In Rel.l 8, multi -PRACH transmission with same beam has been specified in non-SBFD symbols only to enhance coverage. A gNB may configure one or multiple numbers of PRACH transmissions (e g., 2, 4, 8) in a serving cell. It is supported in the technical specifications to differentiate PRACH resources among the multi-PRACH transmissions according to the different number (e g., 1, 2, 4, 8) of PRACH transmissions. A group ofNROs at the same frequency allocation are used for sending a configured N PRACH transmissions. In non-SBFD symbols, a configuration period of PRACH resources (including preambles and / or ROs) for multi-PRACH transmission is introduced as KvSynchronization Signal / PBCH block (SSB)-to-RO association pattern period, where K is equal to or greater than 1 SSB-to- RO association pattern period, and SSB-to-RO association pattern period is specified in [TS 38.213], is implicitly determined as a minimum integer for all configured number of multiple PRACH transmissions such that for each SSB, there is at least one RO group per configured number of multiple PRACH transmissions consisting of ROs associated with the SSB. Within K , groups of N ROs can be determined by a legacy UE. Depending on channel conditions, the legacy UE determines one of one or more groups of / VROs to use for / VPRACH transmissions. The determined groups of N ROs are repeated every Kt.

[0079] At present, there is no solution to realize multi-PRACH transmission for a SBFD capable UE that can enjoy the benefits of introduction of SBFD symbols in XDD operation toimprove coverage of PRACH transmission. A multi-PRACH transmission for the SBFD capable UE should be carefully designed in a way that does not impact on the legacy UE. Further, it should also be addressed how a gNB can differentiate between a SBFD capable UE and a legacy UE, so that the gNB can subsequently schedule Msg3 and / or Msg5 transmissions in SBFD symbols for the SBFD capable UE. Some benefits of introduction of SBFD symbols in XDD operation are to provide more UL time duration to enhance UL coverage, reduce latency, and increase UL capacity.

[0080] There is thus a need for a communication apparatus and a communication method for multi-PRACH transmission in XDD to solve the above-mentioned issues. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.

[0081] Figure 7 shows a schematic diagram illustrating an example configuration of a communication apparatus 700 for multi-PRACH transmission in XDD in accordance with various embodiments of the present disclosure. The communication apparatus 700 may be implemented as a UE or a base station in accordance with the present disclosure. It will be appreciated by a person skilled in the art that the communication apparatus 700 may be referred to as communication device 700 throughout the disclosure. As shown in Figure 7, the communication apparatus 700 may include circuitry 714, at least one radio transmitter 702, at least one radio receiver 704, and at least one antenna 712 (for the sake of simplicity, only one antenna is depicted in Figure 7 for illustration purposes). The circuitry 714 may include at least one controller 706 for use in software and / or hardware aided execution of tasks that the at least one controller 706 is designed to perfonn, including control of communications with one or more other communication apparatuses in a multiple input and multiple output (MIMO) wireless network. The circuitry 714 may furthermore include at least one transmission signal generator 708 and at least one receive signal processor 710. The at least one controller 706 may control the at least one transmission signal generator 708 for generating a downlink signal or a sidelink signal to be sent through the at least one radio transmitter 702 and the at least one receive signal processors 710 for processing an uplink signal, a downlink signal or a si delink signal received through the at least one radio receiver 704 from the one or more other communication apparatuses. The at least one transmission signal generator 708 and the at leastone receive signal processor 710 may be stand-alone modules of the communication apparatus 700 that communicate with the at least one controller 706 for the above-mentioned functions, as shown in Figure 7. Alternatively, the at least one transmission signal generator 708 and the at least one receive signal processor 710 may be included in the at least one controller 706. It is appreciable to those skilled in the art that the arrangement of these functional modules is flexible and may vary depending on the practical needs and / or requirements. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and / or in chipsets. In various embodiments, when in operation, the at least one radio transmitter 702, at least one radio receiver 704, and at least one antenna 712 may be controlled by the at least one controller 706.

[0082] The communication apparatus 700, when in operation, provides functions required for multi-PRACH transmission in XDD For example, the communication apparatus 700 may be a user equipment (UE) such as a SBFD capable UE or a non-SBFD capable UE. As shown in the exemplified method 800 for multi-PRACH transmission in XDD in Figure 8, the first communication apparatus 700, when in operation, is configured to perform the following steps:Step 802: the circuitry 714 (or the at least one controller 706 of the circuitry 714) may determine a RO group from a plurality of RO groups for multiple PRACH transmissions, each of the plurality of RO groups including one or more ROs.; andStep 804: The at least one radio transmitter 702 may transmit a preamble on the one or more ROs of the determined RO group, wherein the one or more ROs include at least one RO in SBFD symbols or at least one RO in non-SBFD symbols.|83| Additionally or alternatively, in step 802, the circuitry 714 (or the at least one controller 806 of the circuitry 714) may determine the RO group based on channel condition and / or capability of the communication apparatus.

[0084] Additionally or alternatively, in step 802, the circuitry 714 (or the at least one controller 806 of the circuitry 714) may determine a configuration period for the plurality of RO groups based on an earliest SBFD symbol of the plurality of RO groups in time domain. Within the configuration period, the circuitry of SBFD capable UE may determine the plurality of RO groups based on a 2-layer searching procedure Each of plurality of RO groups may be associated with a same beam(s) (e.g., SSB-based beam(s)). Following that, depending onchannel condition, the circuitry of SBFD capable UE may determine one RO group of the plurality of RO groups to use for A' P ACH transmissions by using the same beam(s) that are associated with the one RO group. In order to reduce effort of determining for the plurality of RO groups of the circuitry of SBFD capable UE in subsequent configuration period in time domain, gNB can configure to repeat the plurality of RO groups over multiple configuration periods. In other words, the circuitry does not need to determine the plurality of RO groups in subsequent configuration period if the plurality of RO groups has been determined in previous configuration period.[85| Additionally or alternatively, in step 802, the circuitry 714 (or the at least one controller 806 of the circuitry 714) may determine a configuration period for the plurality of RO groups based on an offset period between the configuration period for the plurality of RO groups and a configuration period of the non-SBFD capable communication apparatus (CA), the offset period being determined by a communication device. The communication device may be, for example, a base station or another communication apparatus.[861 Additionally or alternatively, in step 802, before determining a RO group from the plurality of RO groups, the circuitry 714 (or the at least one controller 806 of the circuitry 714) may determine the plurality of RO groups based on a search procedure starting from a virtual RO being located at a lowest frequency resource of a plurality of ROs in both SBFD symbols and non-SBFD symbols, wherein the plurality of ROs being configured by a communication device or specified in technical specifications.[871 Additionally or alternatively, in step 802, before determining a RO group from the plurality of RO groups, the circuitry 714 (or the at least one controller 806 of the circuitry 714) may determine the plurality of RO groups based on a search procedure starting from a first frequency resource or resource index, the first frequency resource or resource index being different from each of a plurality of second frequency resources or indexes at which a plurality of ROs in SBFD symbols are located. For example, in a case where the frequency resources or indexes at which a plurality of ROs in SBFD symbols are located are smaller than the frequency resources or indexes at which a plurality of ROs in non-SBFD symbols are located, the firstfrequency resource or resource index is determined based on any of the plurality of ROs in non-SBFD symbols.

[0088] Additionally or alternatively, in step 802, before determining a RO group from the plurality of RO groups, the circuitry 714 (or the at least one controller 806 of the circuitry 714) may determine the plurality of RO groups based on a search procedure starting from a first frequency resource or resource index, the first frequency resource or resource index being different from each of a plurality of second frequency resources or indexes at which a plurality of ROs in non-SBFD symbols are located. For example, in a case where the frequency resources or indexes at which a plurality of ROs in non-SBFD symbols are located are smaller than the frequency resources or indexes at which a plurality of ROs in SBFD symbols are located, the first frequency resource or resource index is determined based on any of the plurality of ROs in SBFD symbols.

[0089] Additionally or alternatively, in step 802, before determining a RO group from the plurality of RO groups, the circuitry 714 (or the at least one controller 806 of the circuitry 714) may determine the plurality of RO groups based on a search procedure starting from a virtual RO, wherein the virtual RO is located at a lowest or a highest frequency resource or resource index of the plurality of ROs in both SBFD symbols and non-SBFD symbols.

[0090] Additionally or alternatively, in step 802, the circuitry 714 (or the at least one controller 806 of the circuitry 714) may apply a search procedure in each of one or more uplink (UL) subbands, the search procedure starting from a RO at a lowest or a highest frequency resource or resource index of each UL subband in both SBFD symbols and non-SBFD symbols; and determine the plurality of RO groups based on the search procedure. The search procedure may be applied within a configuration period of the plurality of RO groups.

[0091] For example, the communication apparatus 700 may be a communication device such as a base station or a gNodeB (gNB). As shown in the exemplified method 900 for multi- PRACH transmission in XDD in Figure 9, the communication apparatus 700, when in operation, is configured to perform the following steps:Step 902: the circuitry 714 (or the at least one controller 706 of the circuitry 714) may transmit control information relating to a RO group of a plurality of RO groups used for multiple PRACH transmissions, each of the plurality of RO groups including one or more ROs; andStep 904: the at least one radio receiver 704 may receive a preamble on the one or more ROs of the RO group, wherein the one or more ROs include at least one RO in SBFD symbols or at least one RO in non-SBFD symbols.

[0092] According to the present disclosure, a SBFD capable UE may be configured to determine a group of N (e.g., A being an arbitrary whole number such as 2, 4, 8, etc) ROs for APRACH transmissions based on SBFD and non-SBFD symbols. Depending on a value of N, the group of N ROs may span in SBFD symbols, or in non-SBFD symbols, or in both SBFD and non-SBFD symbols. Further, a SBFD capable UE may be configured to determine a group of A ROs for A PRACH transmissions based on SBFD and non-SBFD symbols. The value of N is configured by a gNB. If A is small (e.g., A = 2), the group can include A ROs in either SBFD symbols or in non-SBFD symbols. If A is large (e.g., A = 4 or more), the group can include AROs in both SBFD symbols and non-SBFD symbols.

[0093] In a first approach for determining a group of AROs, the group of AROs may include RO(s) in SBFD symbols and shared RO(s) in non-SBFD symbols. Shared RO(s) in non-SBFD symbols are RO(s) that are shared for use between the SBFD capable UE and the legacy UE. This advantageously maximizes or improves usage of ROs to enhance UL coverage and reduce latency for the SBFD capable UE. Referring to illustration 1000 of Figure 10, for a SBFD capable UE, groups of 2 ROs and groups of 4 ROs may be determined for 2 PRACH and 4 PRACH transmissions, respectively. For legacy UE, the group of 2 ROs in slot 1008 may be shared ROs in non-SBFD symbols only. It will be appreciated that, for simplicity, DL slots are not shown in Figure 10.

[0094] In a second approach for determining a group of A ROs, the group of A ROs can include RO(s) in SBFD symbols and separated RO(s) in non-SBFD symbols. Separated RO(s) in non-SBFD symbols are RO(s) that are separated between a SBFD capable UE and a legacy UE e.g., a separated RO may be used only by either the SBFD capable UE or the legacy UE.Advantageously, if a same preamble is configured to the SBFD capable UE and the legacy UE, provision of PRACH preamble resources for other purposes is improved. Referring to illustration 1100 of Figure 11 , for a SBFD capable UE, groups of 2 or 4 ROs may be determined for 2 PRACH and 4 PRACH transmissions. For a legacy UE, the group of 2 ROs in slot 1102 may be separated ROs in non-SBFD symbols only. It will be appreciated that, for simplicity, DL slots are not shown in Figure 11 An overall advantage for both approaches is to enhance UL coverage and reduce latency for the SBFD capable UE during random access procedure.

[0095] When a group of JVROs spans in both SBFD and non-SBFD symbols, the JVROS may be located in a same frequency allocation of UL sub-band in XDD operation in both SBFD and non-SBFD symbols. Further, when the group of A' ROs spans in SBFD symbols, the N ROs may be located in a same frequency allocation of UL sub-band in XDD operation in SBFD symbols. A legacy UE may be configured to have capability of single PRACH transmission and / or capability of multi-PRACH transmission in non-SBFD symbols.

[0096] Further details for the first approach are discussed below. The group of A' ROs may include one or more RO(s) in SBFD symbols and one or more shared RO(s) in non-SBFD symbols. One or more RO(s) in SBFD symbols is / are only used for a SBFD capable UE, while shared RO(s) in non-SBFD symbols are RO(s) that is / are shared between a SBFD capable UE and a legacy UE (e g., usable by both a SBFD capable UE and a legacy UE) For example, if any shared RO in the group is located in non-SBFD symbols, it is shared between the SBFD capable UE and the legacy UE. Referring to Figure 10, a UL subband #2 (reference 1002) may be configured in SIB1 for a SBFD capable UE in a serving cell. For 2 PRACHs (e.g., N = 2), a group of 2 ROs (e.g., RO group 1004) includes RO#0 andRO#2 associated with beam SSB#0 in SBFD symbols. For 4 PRACHs (e.g., N= 4), a group of 4 ROs, e.g., RO group 1006, includes RO#8, RO#10, RO#14, and RO#20, which are associated with beam SSB#2, in both SBFD and non-SBFD symbols.

[0097] A preamble of a SBFD capable UE may be separated from a legacy UE to differentiate the SBFD capable UE from a legacy UE (e.g., different preambles are used for the SBFD capable UE and the legacy UE). The separated preamble of the SBFD capable UE may be configured by a gNB (e.g., a higher-layer parameter FeatureCombinationPr eambles inRACH-ConfigCommon). The separated preamble may be associated with a determined group of N ROs based on legacy SSB-to-RO mapping. For example, in Figure 10, a RO group 1008 including RO#14 and RO#20 for 2 PRACHs in non-SBFD symbols may be shared ROs that are shared by the SBFD capable UE and the legacy UE. Assuming there are 2 separate preambles #0 and #1 associated with the RO group 1008 for the SBFD capable and the legacy UE respectively, the SBFD capable UE may send preamble #0 over RO#14 and RO#20, while the legacy UE sends preamble #1 over RO#14 and RO#20. This advantageously enables a gNB to differentiate between a SBFD capable UE and a legacy UE.

[0098] A configuration period of PRACH resources for a SBFD capable UE ( / f2) may be different from that of a legacy UE (A . In an option 1, K2may be implicitly defined based on a configuration of an earliest SBFD symbol for the SBFD capable UE in time-domain (e g., a SBFD symbol that is located at the earliest possible time slot within the configuration period K2) by using a legacy method. An advantage is that there is no impact on specifications as a legacy method is reused. In an option 2 with reference to illustration 1200 of Figure 12 in which / ^configuration period 1202, K = configuration period 1204, and Aoffset= offset period 1206,= K + Aoffset, where an offset period Aoffsetis used for integrating configuration period between the SBFD capable UE and a legacy UE. In this example, gNB configures 2 UL subbands e.g., subband #2 1208 and subband #3 1210 for XDD operation Aoffsetcan be implicitly determined (e g., based on a configuration of an earliest SBFD symbol) or configured. Advantageously, ifoffsetis configured by gNB, gNB can flexibly configure the starting RO of the group of ROs in SBFD symbols for the SBFD capable UE.

[0099] In Master Information Block / System Information Block (MIB / SIB), a gNB may configure a set #1 of preambles for the SBFD capable UEs, a set #2 of preambles for the legacy UEs, ROs in SBFD symbols for SBFD capable UEs, and ROs in non-SBFD symbols shared for both the SBFD capable UEs and the legacy UEs. Depending on channel condition (e.g., measured RSRP of SSB-based beams) and UE capability (SBFD capable UE or a legacy UE), a SBFD capable UE may be configured to determine a group of N ROs, which is one of a plurality of groups of A ROs, based on SBFD and non-SBFD symbols, as well as a preamble from the set #1 of preambles. The SBFD capable UE may then transmit the preamble on one or more ROs of the determined one of the plurality of groups of A ROs to the gNB in message1 (Msgl). On the other hand, a legacy UE may be configured to determine one of a plurality of groups of A ROs based on non-SBFD symbols, as well as a preamble from the Set #2 of preambles. The legacy UE may transmit the preamble on one or more ROs of the determined group of N ROs to gNB in Msgl. Thus, depending on whether the UE is a SBFD capable UE or a legacy UE, the one or more ROs of the determined group of .V ROs may include at least one RO in SBFD symbols or at least one RO in non-SBFD symbols. Upon decoding of the preamble (e g., transmitted by the SBFD capable or legacy UE), gNB is able to determine whether the UE that transmitted the preamble is a SBFD capable UE or a legacy UE. If a SBFD capable UE is identified, the gNB can subsequently schedule message 3 (Msg3) and / or message 5 (Msg5) transmissions in SBFD symbols for the SBFD capable UE. Note that Msg3 is sent overPUSCHto carry RRCSetupRequest to gNB. Following that, gNB sends a message 4 (Msg4) over PDSCH to carry RRCSetup to the SBFD capable UE (contention resolution). After Msg4, the SBFD capable UE sends a PUSCH carrying RRCSetupComplete (i.e , Msg5) to confirm a successful completion of an RRC connection.

[0100] Further details for the second approach are discussed below. A SBFD capable UE may be configured to determine a group of A ROs for A PR AC H transmissions based on SBFD and non-SBFD symbols. Depending on a value of N, the group of N ROs may span in SBFD symbols, or in non-SBFD symbols, or in both SBFD and non-SBFD symbols. The group of N ROs can include RO(s) in SBFD symbols and separated RO(s) in non-SBFD symbols. Separated RO(s) in non-SBFD symbols are RO(s) that are separated between a SBFD capable UE and a legacy UE e g., a separated RO may be used only by either a SBFD capable UE or a legacy UE. Thus, the ROs in SBFD symbols and the separated ROs can advantageously be used to differentiate between the SBFD capable UE and the legacy UE. The separated RO(s) of the SBFD capable UE can be configured by gNB, e g., a higher-layer parameter AdditionalRACH-Config in BWP-UplmkCommon. A same or separate preamble can be configured to the SBFD capable UE and the legacy UE by gNB, e g , a higher-layer parameter FeatureCombinalionPreambles. The same or separate preamble may be associated with the determined group of A ROs based on legacy SSB-to-RO mapping. A configuration period of PRACH resources for the SBFD capable UE (e.g., having a configuration period A2) can be different from that of the legacy UE (e g , having a configuration period R-A Option 1 or option2 of the first approach can be used for the second approach to determine the configurationperiods. Advantageously, if a same preamble can be configured to the SBFD capable UE and the legacy UE, it can improve provision of PRACH preamble resources for other purposes.

[0101] In a first alternative for the first approach and the second approach, a SBFD capable UE may be configured to determine a group of A' ROs for N PRACH transmissions based on non-SBFD symbols only. The group of A' ROs can span in non-SBFD symbols, and may be based on one of 2 options. In an option (a), the group of A' ROs may be based on shared ROs with different preamble in non-SBFD symbols. In an option (b), the group of N ROs may be based on separated ROs in non-SBFD symbols. ROs in non-SBFD symbols can be used for the SBFD capable UE and / or the legacy UE, where the ROs can be shared ROs and / or separated ROs. The shared ROs refer to ROs that are usable by both the SBFD capable UE and the legacy UE, while the separated ROs refer to ROs that can only be used by either the SBFD capable UE or the legacy UE. An advantage of the first alternative is that there is no specification impact on the existing Rel. 18 multi-PRACH transmission and no impact on legacy UE.

[0102] In a second alternative for the first approach and the second approach, a SBFD capable UE may be configured to determine a group of N ROs for N PRACH transmissions based on SBFD symbols only. The group of N ROs can span in SBFD symbols, and ROs used for determining the group of A' ROs can include ROs in SBFD symbols, wherein a same or separate preamble can be configured to the SBFD capable UE and the legacy UE by gNB. An advantage of the second alternative is that there is no specification impact on the existing Rel. 18 multi- PRACH transmission and no impact on legacy UE.[103J The first approach or the second approach as described above allows a gNB to configure that, in SBFD symbols, one set of groups of A' ROs can be determined for the SBFD capable UE, and in non-SBFD symbols, one or more sets of groups ofrVROs can be determined, where one of the one or more sets of groups of A' ROs can be determined for the SBFD capable UE, and the remaining of the one or more sets of groups of A' ROs can be determined for the legacy UE and SBFD capable UE.

[0104] Further, the first approach, the second approach or the first alternative as described above allows a gNB to configure that, in non-SBFD symbols, one or more sets of groups of N ROs can be determined, where one of the one or more sets of groups of N ROs can be determined for the SBFD capable UE, and the remaining of the one or more sets of groups of A' ROs can be determined for the legacy UE and SBFD capable UE.

[0105] Details of a searching procedure for determining a plurality of groups of N ROs are explained below. A first starting RO is a RO that is located at an earliest time instance and the lowest frequency resource index in a configuration period. Beginning from the first starting RO, a 2-layer searching procedure is applied to determine groups of A' ROs in Kt. Firstly, a starting RO of a group of A' ROs is determined, then the remaining / V- l ROs located at a same nRAfrequency resource index (where nRAis equal to or greater than zero) as the starting RO are also determined. The remaining AM ROs are the next AM ROs after the starting RO with increasing order of time resource indexes and associated with the same SSB(s) as the starting RO. Secondly, the starting RO of each of the other remaining RO groups and the remaining N- 1 ROs of each RO group are determined sequentially. For determining a starting RO of each of a plurality of groups of N ROs, a UE begins searching from the first starting RO. If a time offset is configured, a starting RO of the first RO group for each nRAis determined as the first valid RO in the following order: in increasing order of frequency resource index for frequency multiplexed ROs, and in increasing order of time resource index.

[0106] Referring to illustration 1300 of Figure 13, there are 8 groups of ROs for 2 PRACHs that are determined based on the method in non-SBFD symbols in a configuration period Kt. For example, the 2-layer searching procedure begins from a first starting RO 1302 (located at the earliest time instance and lowest frequency resource index in K ), determines a next RO 1304 within the same RO group 1306 as the first starting RO 1302 (e g., in increasing order of time resource index), then moves to a next RO group 1308 (e g., in increasing order of frequency resource index) to determine a starting RO of the RO group 1308 (e g., RO 1307) and then the remaining ROs in the RO group 1308 (e g., only RO 1309 since each group has only 2 ROs). The search continues to RO groups 1310 and then 1312, and then continues (e.g., in increasing order of time resource index) to RO groups 1314, 1316, 1318 and 1320.

[0107] An available RO is identified as a valid RO by using existing validation rules in TS 38.213. The 2-layer searching procedure for determining groups of JVROs is performed after applying the existing validation rules. Available ROs are validated as valid ROs based on the existing validation rules, then groups of ArROs are determined based on valid ROs. Thus, each RO group of A' ROs includes N valid ROs.

[0108] However, the 2-layer searching procedure for determining groups of AfROs does not work well in XDD operation, as a gNB or UE may not consider numerous ROs when determining groups of A' ROs for A' PRACH transmissions, such that a fewer number of groups of N ROs are determined, causing a higher PRACH collision probability. This is because time and frequency resources of UL subband(s) in SBFD symbols are different from that in non- SBFD symbols. For example, referring to illustration 1400 of Figure 14, assuming that RO#0 1402 is determined as a first starting RO because it locates at the earliest time instance in K2, the existing method will not consider 4 ROs (RO#12, RO#13, RO#18, and RO#19 as shown in ROs 1404) when determining possible groups of 2 ROs for 2 PRACH transmissions, hence 2 groups of ROs are not counted. Further referring to illustration 1500 of Figure 15, assuming that RO#14 1502 is determined as a first starting RO because it locates at the lowest frequency resource index nRAin K2, the existing method will not consider 12 ROs (RO#0 -RO#11 as shown in ROs 1504) when determining possible groups of 2 ROs for 2 PRACH transmissions, hence 6 groups of ROs are not counted. It will be appreciated that downlink (D) slots are not shown in this example for simplicity

[0109] Thus, in order to determine a group of N ROs for a SBFD capable UE according to the present disclosure, one of the following solutions may be used.[HO] In a first solution, referring to illustration 1600 of Figure 16 (downlink (D) slots are not shown in this example for simplicity), the 2-layer searching procedure may be applied within the configuration period K2based on a virtual RO 1602 (after applying the existing validation rules in TS 38.213). The purpose of the virtual RO 1602 is to provide a first starting RO to apply the 2-layer searching procedure. The virtual RO may be located at a lowest or a highest frequency resource or resource index of a plurality of ROs in both SBFD symbols and non-SBFD symbols, wherein the plurality of ROs are configured by a gNB or specified intechnical specifications. The virtual RO may also be located at an earliest time resource or resource index of the plurality of ROs in both SBFD symbols and non-SBFD symbols. The earliest time resource or resource index is a first symbol or slot of the plurality of ROs in both SBFD symbols and non-SBFD symbols, which are configured by a gNB or specified in technical specifications.[Hl] A UE begins searching from the virtual RO 1602 for determining a starting RO of each of a plurality of groups of / valid ROs. If the virtual RO 1602 matches with a valid RO, it is included in the group of N valid ROs and the remaining JV-1 ROS located at a same frequency resource index nRAas the valid RO are also determined Otherwise, it is not counted and not included in the group of A valid ROs. In this case, as evident from Figure 16, the virtual RO 1602 is not a valid RO. Therefore, the virtual RO 1602 is not counted and the 2-layer searching procedure continues. For example, the search procedure may continue from another virtual RO located at a next higher frequency resource or resource index to determine whether the another virtual RO matches with a valid RO. It will be appreciated that there may be one or more virtual ROs during the searching procedure. Thus, by repeating the search throughout all the available resources or resource indexes within a configuration period, the UE determines all available groups of ROs within the configuration period. The virtual RO may be defined in a legacy TDD band (considering both SBFD symbols and non-SBFD symbols) as follows: a time instance is defined based on an earliest time instance from all ROs in both SBFD symbols and non-SBFD symbols, and a frequency resources or resource index is defined based on a lowest frequency resource or resource index from all ROs in both SBFD symbols and non- SBFD symbols. The virtual RO can be in a downlink slot or uplink slot. The virtual RO may be located at a highest frequency resource or resource index of the plurality of ROs in both SBFD symbols and non-SBFD symbols.

[0112] It will be appreciated that a virtual RO need not be defined as long as the search procedure can begin from a starting location that enables all RO groups to be determined. For example, a UE may be configured to determine a plurality of RO groups based on a search procedure starting from a first frequency resource or resource index. The first frequency resource or resource index may be different from a plurality of second frequency resources or indexes at which a plurality of ROs of SBFD symbols are located. The first frequency resourceor resource index may be different from a plurality of second frequency resources or indexes at which a plurality of ROs of non-SBFD symbols are located.

[0113] The virtual RO may be defined in a legacy TDD band (considering both SBFD symbols and non-SBFD symbols) as follow: A time instance is defined based on the earliest time instance from all ROs in both SBFD symbols and non-SBFD symbols, and / or a frequency resource index is defined based on the lowest or the highest frequency resource index from all ROs in both SBFD symbols and non-SBFD symbols. In the 2-layer searching procedure, determination of a starting RO of each of a plurality of groups of / V ROs may be modified as follows. If a time offset is configured, a starting RO of the first RO group for each nRAmay be determined as a first valid RO in the following order: in increasing or decreasing order of frequency resource index for frequency multiplexed ROs, and / or in increasing order of time resource index. A starting RO of the / / -th RO group for each nRAmay be determined after N valid ROs from the starting RO of the (n-1 )-th RO group for the same nRA. If a time offset is not configured, a starting RO of a first RO group is the first valid RO from the starting point, and a starting RO of each of the remaining RO groups are determined as a first valid RO after a previous RO group in the following order: in increasing or decreasing order of frequency resource index for frequency multiplexed ROs, and in increasing order of time resource index. A group of N ROs can include ROs in SBFD symbols and / or both of shared ROs and separate ROs in non-SBFD symbols. Advantageously, more ROs can be used for determining a group of A ROs.

[0114] Advantageously, the SBFD capable UE can determine all possible groups of A ROs (e g., it may then select one RO group to use for A PRACH transmissions based on channel condition as mentioned in the first approach) such that probability of a PRACH collision is reduced. For a legacy UE, it applies the 2-layer searching procedure for ROs in non-SBFD symbol as a legacy operation. It will be appreciated that the first solution is applicable for both the first and second approaches.

[0115] In a second solution, according to a starting RO per UL subband, the 2-layer searching procedure may be applied per UL subband within the configuration period K2(after applying the existing validation rules in TS 38.213), e g., starting ROs 1702 as shown in illustration 1700of Figure 17 (downlink (D) slots are not shown in this example for simplicity). The starting RO of a UL subband may be a valid RO at the earliest time instance and / or the lowest frequency resource index in the UL subband in both SBFD and non-SBFD symbols. A search procedure may thus be applied in each of one or more UL subbands within a configuration period of the plurality of RO groups, the search procedure starting from a RO at a lowest or a highest frequency resource index of each UL subband in both SBFD symbols and non-SBFD symbols, and the plurality of RO groups may be determined based on the search procedure. Further, a RO group may also be determined from the plurality of RO groups for transmission of a preamble on one or more ROs of the determined RO group. The RO may be located at the earliest time instance of each UL subband in both SBFD symbols and non-SBFD symbols. Advantageously, there is less specification impact when the second solution is implemented and probability of a PRACH collision is reduced. It will be appreciated that the second solution is applicable for both the first approach and the second approach.

[0116] Tn the first approach or the second approach, assuming that there are a plurality of UL subbands that are configured in a serving cell and each of the UL subbands is configured to a SBFD capable UE (such as in a contention free random access (CFRA) case), the configuration period K2may be determined for each of the plurality of UL subbands according to either option 1 or option 2. This advantageously enable more flexibility of configuration of PRACH resources per periodicity.

[0117] In the first approach or second approach, a UE may be configured to determine a group of AROs based on frequency hopping in one or more SBFD symbols and non-SBFD symbols. The group may include N ROs with different frequency allocations according to frequency hopping in SBFD and non-SBFD symbols. Advantageously, it is possible to achieve frequency hopping gain.

[0118] A hybrid approach based on the first and second approaches may be implemented, in which gNB configures a same preamble associated with a group of A ROs that is fully located in SBFD symbols, while the gNB also configures a different preamble associated with a group of A ROs that is fully located in non-SBFD symbols ROs in the non-SBFD symbols can be shared or separated between SBFD capable UE and legacy UE. Advantageously, it is possibleto achieve more flexibility of configuration of PRACH resources. It will be appreciated that the first, second and hybrid approaches are applicable for both contention based random access (CBRA) and CFRA scenarios.

[0119] In a variation of solution 2, a 2-layer searching procedure may be applied by searching from an earliest time instance from all ROs in both SBFD symbols and non-SBFD symbols in time-domain first, and then in frequency-domain. For determining a starting RO of each of a plurality of groups of N ROs, a UE may begin searching in time-domain first and then in frequency-domain. If a time offset is configured, a starting RO of a first RO group for each nRAis determined as a first valid RO in the following order: in increasing order of time resource index, and in increasing order of frequency resource index for frequency multiplexed ROs. A starting RO of the / / -th RO group for each nRAis determined after N valid ROs from the starting RO of the (n- l)-th RO group for the same nRA. If a time offset is not configured, a starting RO of a first RO group is a first valid RO from the first starting RO (e g., RO 1302). A starting RO of each of the remaining RO groups are determined as a first valid RO after a previous RO group in the following order: in increasing order of time resource index, and in increasing order of frequency resource index for frequency multiplexed ROs.

[0120] Further, there is a case that RO(s) in SBFD symbols is / are shared among the SBFD capable UE and the legacy UE, if SBFD symbols based on legacy flexible symbols are supported. For such a case, the first approach may be modified such that the group of ArROs can include separated RO(s) in SBFD symbols and shared RO(s) in SBFD symbols and / or in non-SBFD symbols. Further, the second approach may be modified such that the group of N ROs can include separated RO(s) in SBFD symbols and / or in non-SBFD symbols.

[0121] Figure 18 shows a diagram 1800 illustrating an example of a random access procedure between a UE and a gNB for enabling multi-PRACH transmission in XDD. In step 1802, the gNB configures PRACH resources for SBFD capable UEs and legacy UEs based on either the first approach or the second approach in MIB / SIB. In step 1804, a SBFD capable UE determines a preamble and a group of N ROs for N PRACH transmissions based on SBFD symbols and non-SBFD symbols. This step is applicable for approaches 1 and 2, and may depend on channel conditions, UE capability (e.g., whether the UE is a SBFD capable UE or alegacy UE), and / or configuration (e g., configuration by the gNB and / or the UE). Tn step 1806, the UE sends A' PRACH transmissions in Msgl in UL to the gNB. In step 1808, the gNB transmits Msg2 random access response (RAR) in DL to the UE. In step 1810, the UE transmits a Msg3 Physical Uplink Shared Channel (PUSCH) in UL to the gNB. In step 1812, the gNB transmits a Msg4 contention resolution in DL to the UE. In step 1814, the UE transmits a Msg5 PUSCH in UL to the gNB.[122J Figure 19 shows a flowchart 1900 illustrating a communication method implemented by a UE for enabling a multi-PRACH transmission in XDD. In step 1902, a UE (e.g., a SBFD capable UE) determines a preamble and a group of A' ROs for N PRACH transmissions based on SBFD and non-SBFD symbols. In step 1904, the UE transmits the preamble based on the determined one of a plurality of A' ROs to a gNB in Msgl. In step 1906, the UE receives a subsequent configuration of Msg3 (e.g., in response to a Msg2 sent from the UE to the gNB) and / or Msg5 (e.g., in response to a Msg4 sent from the UE to the gNB) from gNB. In step 1908, the UE sends Msg3 and / or Msg5 transmissions in SBFD symbols for the UE based on corresponding configuration ofMsg3 and / or Msg5 respectively.

[0123] Figure 20 shows a flowchart illustrating a communication method implemented by a gNB for enabling a multi-PRACH transmission in XDD according to various embodiments of the present disclosure. In step 2002, a gNB configures PRACH resources for SBFD capable UEs and legacy UEs based on the first or second approach in MIB / SIB. The configuration may be sent to a UE as control information relating to a RO group of a plurality of RO groups used for multi-PRACH transmissions, wherein each of the plurality of RO groups include one or more ROs. In step 2004, the gNB receives APRACH transmissions including a preamble from a UE. The preamble may be sent on the one or more ROs of the RO group, wherein the one or more ROs include at least one RO in SBFD symbols or at least one RO in non-SBFD symbols. At step 2006, the gNB determines whether the UE is a SBFD capable UE or legacy UE upon decoding the received preamble, and schedules Msg3 and / or Msg5 transmissions in SBFD symbols with Msg2 and / or Msg4 respectively if the UE is a SBFD capable UE e g., the gNB transmits Msg2 and / or Msg4 to the UE.

[0124] Although the above descriptions mainly focus on a case of multi-PRACH transmission with same beam (e.g., a multi-PRACH transmission is performed by using a same beam), itwill be appreciated that they can be applicable to another case of multi-PRACH transmission with different beams (e.g., multiple beams). In this case, a group of / VROs can be divided into multiple sub-groups, where each sub-group includes a smaller number of / V, ROs, where 1 < iVj < N, and each RO from the group of N ROs is only included in a sub-group. Each subgroup of JVj ROs is used to send a same preamble by using a different beam, wherein the different beam is defined based on an association of these N[ ROs with the different beam, and this association may be configured by gNB based on legacy SSB-to-RO mapping or new SSB- to-RO mapping. The new SSB-to-RO mapping may be a mapping between a SSB index with sub-group of Ni ROs. The same preamble means that one preamble is used for the multiple sub-groups of N[ ROs. In summary, a multi-PRACH transmission may be performed by using the multiple sub-groups of N,- ROs and multiple SSB-based beams. Alternatively, a multi- PRACH transmission may be performed by using the multiple sub-groups of N ROs and multiple CSI-based beams.

[0125] According to the present disclosure, various examples below have been described:1. A communication apparatus comprising: circuitry, which in operation, determines a random access channel occasion (RO) group from a plurality of RO groups for multiple Physical Random Access Channel (PRACH) transmissions, each of the plurality of RO groups including one or more ROs; and a transmitter, which in operation, transmits a preamble on the one or more ROs of the determined RO group, wherein the one or more ROs include at least one RO in subband nonoverlapping full duplex (SBFD) symbols or at least one RO in non-SBFD symbols.2. The communication apparatus according to example 1, wherein the at least one RO indicates whether the communication apparatus is a SBFD capable communication apparatus (CA) or a non-SBFD capable CA.3. The communication apparatus according to example 1, wherein the one or more ROs of the determined RO group are located at a same frequency resource allocation in SBFD symbols and / or non-SBFD symbols.4. The communication apparatus according to example 1 , wherein the circuitry determines the RO group based on channel condition and / or capability of the communication apparatus.5. The communication apparatus according to example 1, wherein the at least one RO is a shared RO that is usable by both a SBFD capable CA and a non-SBFD capable CA6. The communication apparatus according to example 1, wherein the at least one RO is a separated RO that is usable only by a SBFD capable CA or a non-SBFD capable CA.7. The communication apparatus according to example 1 or 5, wherein the one or more ROs of the determined RO group are one or more shared ROs in non-SBFD symbols.8. The communication apparatus according to example 1 or 6, wherein the one or more ROs of the determined RO group are one or more separated ROs in non-SBFD symbols.9. The communication apparatus according to example 1, wherein the one or more ROs of the determined RO group are one or more ROs in SBFD symbols10. The communication apparatus according to example 1 or 5, wherein the at least one RO of the one or more ROs of the determined RO group are in SBFD symbols, and the remaining of the one or more ROs of the determined RO group are shared ROs in non-SBFD symbols.11. The communication apparatus according to example 1 or 6, wherein the at least one RO of the one or more ROs of the determined RO group are in SBFD symbols, and the remaining of the one or more ROs of the determined RO group are separated ROs in non-SBFD symbols.12. The communication apparatus according to example 6, wherein the communication apparatus is the SBFD capable CA, and the preamble associated with the one or more ROs of the determined RO group is same as a preamble used for the non-SBFD capable CA.13. The communication apparatus according to example 5 or 6, wherein the communication apparatus is the SBFD capable CA, and the preamble associated with the one or more ROs of the determined RO group is different from a preamble used for the non-SBFD capable CA.14. The communication apparatus according to any one of examples 1 to 3, wherein the circuitry is configured to determine a configuration period for the plurality of RO groups based on an earliest SBFD symbol of the plurality of RO groups in time domain.15. The communication apparatus according to example 2 or 3, wherein the circuitry is configured to determine a configuration period for the plurality of RO groups based on an offset period between the configuration period for the plurality of RO groups and a configuration period of the non-SBFD capable communication apparatus (CA), the offset period being determined by a communication device.16. The communication apparatus according to any one of examples 1-15 , wherein the circuitry is configured to determine the plurality of RO groups based on a search procedure starting from a virtual RO being located at a lowest frequency resource of a plurality of ROs in both SBFD symbols and non-SBFD symbols, wherein the plurality of ROs being configured by a communication device or specified in technical specifications.17. The communication apparatus according to any one of examples 1-15, wherein the circuitry is configured to determine the plurality of RO groups based on a search procedure starting from a first frequency resource or resource index, the first frequency resource or resource index being different from each of a plurality of second frequency resources or indexes at which a plurality of ROs in SBFD symbols are located.18. The communication apparatus according to any one of examples 1-15, wherein the circuitry is configured to determine the plurality of RO groups based on a search procedure starting from a first frequency resource or resource index, the first frequency resource or index being different from each of a plurality of second frequency resources or indexes at which a plurality of ROs in non-SBFD symbols are located.19. The communication apparatus according to example 1, wherein the circuitry is configured to determine the plurality of RO groups based on a search procedure starting from a virtual RO, wherein the virtual RO is located at a highest frequency resource of the plurality of ROs in both SBFD symbols and non-SBFD symbols.20. The communication apparatus according to example 1, wherein the circuitry is configured to: apply a search procedure in each of one or more uplink (UL) subbands within a configuration period of the plurality of RO groups, the search procedure starting from a RO at a lowest or a highest frequency resource index of each UL subband in both SBFD symbols and non-SBFD symbols; and determine the plurality of RO groups based on the search procedure.21. The communication apparatus according to example 18 or 19, wherein the virtual RO is located at earliest time instance of the plurality of ROs22. The communication apparatus according to example 20, wherein the RO is located at an earliest time instance of each UL subband in both SBFD symbols and non-SBFD symbols.23. The communication apparatus according to any one of examples 18- 19, wherein the determination of the plurality of RO groups is based on frequency hopping in the one or more SBFD symbols and non-SBFD symbols.24. A communication device comprising: a transmitter, which in operation, transmits control information relating to a random access channel occasion (RO) group of a plurality of RO groups used for multiple Physical Random Access Channel (PRACH) transmissions, each of the plurality of RO groups including one or more ROs; and a receiver, which in operation, receives a preamble on the one or more ROs of the RO group, wherein the one or more ROs include at least one RO in subband non-overlapping full duplex (SBFD) symbols or at least one RO in non-SBFD symbols25. A communication method implemented by a communication apparatus, comprising: determining a random access channel occasion (RO) group from a plurality of RO groups for multiple Physical Random Access Channel (PRACH) transmissions, each of the plurality of RO groups including one or more ROs; and transmitting a preamble on the one or more ROs of the determined RO group, wherein the one or more ROs include at least one RO in subband non-overlapping full duplex (SBFD) symbols or at least one RO in non-SBFD symbols.26. A communication method implemented by a communication device, comprising: transmitting control information relating to a random access channel occasion (RO) group of a plurality of RO groups used for multiple Physical Random Access Channel (PRACH) transmissions, each of the plurality of RO groups including one or more ROs; and receiving a preamble on the one or more ROs of the RO group, wherein the one or more ROs include at least one RO in subband non-overlapping full duplex (SBFD) symbols or at least one RO in non-SBFD symbols. ri26] In the following paragraphs, certain exemplifying embodiments are explained with reference to terms related to 5G core network and the present disclosure regarding communication apparatuses and methods for allocating one or more additional operating windows between two semi-statically configured SL DRX cycles for a reception or a transmission of a SL signal, namely:Control Signals

[0127] In the present disclosure, the downlink control signal (information) related to the present disclosure may be a signal (information) transmitted through PDCCH of the physical layer or may be a signal (information) transmitted through a MAC Control Element (CE) of the higher layer or the RRC. The downlink control signal may be a pre-defined signal (information).

[0128] The uplink control signal (information) related to the present disclosure may be a signal (information) transmitted through PUCCH of the physical layer or may be a signal (information) transmitted through a MAC CE of the higher layer or the RRC. Further, theuplink control signal may be a pre-defined signal (information). The uplink control signal may be replaced with uplink control information (UCI), the 1st stage sidelink control information (SCI) or the 2nd stage SCI.Base Station

[0129] In the present disclosure, the base station may be a Transmission Reception Point (TRP), a clusterhead, 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 agateway, for example. Further, in sidelink communication, a terminal may be adopted instead of a base station. The base station may be a relay apparatus that relays communication between a higher node and a terminal. The base station may be a roadside unit as well.Uplink / Downlink / Sidelink

[0130] The present disclosure may be applied to any of uplink, downlink and sidelink.

[0131] The present disclosure may be applied to, for example, uplink channels, such as PUSCH, PUCCH, and PRACH, downlink channels, such as PDSCH, PDCCH, and PBCH, and side link channels, such as Physical Sidelink Shared Channel (PSSCH), Physical Sidelink Control Channel (PSCCH), and Physical Sidelink Broadcast Channel (PSBCH).

[0132] PDCCH, PDSCH, PUSCH, and PUCCH are examples of a downlink control channel, a downlink data channel, an uplink data channel, and an uplink control channel, respectively. PSCCH and PSSCH are examples of a sidelink control channel and a sidelink data channel, respectively. PBCH and PSBCH are examples of broadcast channels, respectively, and PRACH is an example of a random access channel.Data Channel s / Control Channels

[0133] The present disclosure may be applied to any of data channels and control channels The channels in the present disclosure may be replaced with data channels including PDSCH, PUSCH and PSSCH and / or control channels including PDCCH, PUCCH, PBCH, PSCCH, and PSBCH.Reference Signals

[0134] In the present disclosure, the reference signals are signals known to both a base station and a mobile station and each reference signal may be referred to as a Reference Signal (RS) or sometimes a pilot signal. The reference signal may be any of a DMRS, a Channel State Information - Reference Signal (CSI-RS), a Tracking Reference Signal (TRS), a Phase Tracking Reference Signal (PTRS), a Cell-specific Reference Signal (CRS), and a Sounding Reference Signal (SRS).Time Intervals

[0135] In the present disclosure, time resource units are not limited to one or a combination of slots and symbols, and may be time resource units, such as frames, super-frames, subframes, slots, time slot sub-slots, mini-slots, or time resource units, such as symbols, Orthogonal Frequency Division Multiplexing (OFDM) symbols, Single Carrier -Frequency Division Multiplexing Access (SC-FDMA) symbols, or other time resource units. The number of symbols included in one slot is not limited to any number of symbols exemplified in the embodiment(s) described above, and may be other numbers of symbols.Frequency Bands

[0136] The present disclosure may be applied to any of a licensed band and an unlicensed band.Communication

[0137] The present disclosure may be applied to any of communication between a base station and a terminal (Uu-link communication), communication between a terminal and a terminal(Sidelink communication), and Vehicle to Everything (V2X) communication. The channels in the present disclosure may be replaced with PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, and PBCH.

[0138] In addition, the present disclosure may be applied to any of a terrestrial network or a network other than a terrestrial network (NTN: Non-Terrestrial Network) using a satellite or a High Altitude Pseudo Satellite (HAPS). In addition, the present disclosure may be applied to a network having a large cell size, and a terrestrial network with a large delay compared with a symbol length or a slot length, such as an ultra-wideband transmission network.Antenna Ports

[0139] An antenna port refers to a logical antenna (antenna group) formed of one or more physical antenna(s). That is, the antenna port does not necessarily refer to one physical antenna and sometimes refers to an array antenna formed of multiple antennas or the like For example, it is not defined how many physical antennas form the antenna port, and instead, the antenna port is defined as the minimum unit through which a terminal is allowed to transmit a reference signal. The antenna port may also be defined as the minimum unit for multiplication of a precoding vector weighting.

[0140] The present disclosure can be realized by software, hardware, or software in cooperation with hardware Each functional block used in the description of each embodiment described above can be partly or entirely realized by an LSI such as an integrated circuit, and each process described in each embodiment may be controlled partly or entirely by the same LSI or a combination of LSIs. The LSI may be individually formed as chips, or one chip may be formed so as to include a part or all of the functional blocks. The LSI may include a data input and output coupled thereto. The LSI here may be referred to as an IC, a system LSI, a super LSI, or an ultra LSI depending on a difference in the degree of integration. However, the technique of implementing an integrated circuit is not limited to the LSI and may be realized by using a dedicated circuit, a general-purpose processor, or a special-purpose processor. In addition, a FPGA (Field Programmable Gate Array) that can be programmed after the manufacture of the LSI or a reconfigurable processor in which the connections and the settingsof circuit cells disposed inside the LSI can be reconfigured may be used. The present disclosure can be realized as digital processing or analogue processing. If future integrated circuit technology replaces LSIs as a result of the advancement of semiconductor technology or other derivative technology, the functional blocks could be integrated using the future integrated circuit technology. Biotechnology can also be applied.

[0141] The present disclosure can be realized by any kind of apparatus, device or system having a function of communication, which is referred to as a communication apparatus.[142| The communication apparatus may comprise a transceiver and processing / control circuitry. The transceiver may comprise and / or function as a receiver and a transmitter. The transceiver, as the transmitter and receiver, may include an RF (radio frequency) module including amplifiers, RF modulators / demodulators and the like, and one or more antennas.

[0143] Some non-limiting examples of such a communication apparatus include a phone (e.g, cellular (cell) phone, smart phone), a tablet, a personal computer (PC) (e.g, laptop, desktop, netbook), a camera (e.g., digital still / video camera), a digital player (digital audio / video player), a wearable device (e.g., wearable camera, smart watch, tracking device), a game console, a digital book reader, a telehealth / telemedicine (remote health and medicine) device, and a vehicle providing communication functionality (e g., automotive, airplane, ship), and various combinations thereof.

[0144] The communication apparatus is not limited to be portable or movable, and may also include any kind of apparatus, device or system being non-portable or stationary, such as a smart home device (e.g., an appliance, lighting, smart meter, control panel), a vending machine, and any other “things” in a network of an “Internet of Things (IoT)”.

[0145] The communication may include exchanging data through, for example, a cellular system, a wireless LAN system, a satellite system, etc., and various combinations thereof.

[0146] The communication apparatus may comprise a device such as a controller or a sensor which is coupled to a communication device performing a function of communication described in the present disclosure. For example, the communication apparatus may comprisea controller or a sensor that generates control signals or data signals which are used by a communication device performing a communication function of the communication apparatus.

[0147] The communication apparatus also may include an infrastructure facility, such as a base station, an access point, and any other apparatus, device or system that communicates with or controls apparatuses such as those in the above non-limiting examples.

[0148] It will be appreciated by a person skilled in the art that numerous variations and / or modifications may be made to the present disclosure as shown in the specific embodiments without departing from the spirit or scope of the disclosure as broadly described. The present embodiments are, therefore, to be considered in all respects illustrative and not restrictive.

Claims

CLAIMS1. A communication apparatus comprising: circuitry, which in operation, determines a random access channel occasion (RO) group from a plurality of RO groups for multiple Physical Random Access Channel (PRACH) transmissions, each of the plurality of RO groups including one or more ROs; and a transmitter, which in operation, transmits a preamble on the one or more ROs of the determined RO group, wherein the one or more ROs include at least one RO in subband nonoverlapping full duplex (SBFD) symbols or at least one RO in non-SBFD symbols.

2. The communication apparatus according to claim 1, wherein the at least one RO indicates whether the communication apparatus is a SBFD capable communication apparatus (CA) or a non-SBFD capable CA.

3. The communication apparatus according to claim 1, wherein the one or more ROs of the determined RO group are located at a same frequency resource allocation in SBFD symbols and / or non-SBFD symbols.

4. The communication apparatus according to claim 1, wherein the circuitry determines the RO group based on channel condition and / or capability of the communication apparatus.

5. The communication apparatus according to claim 1, wherein the at least one RO is a shared RO that is usable by both a SBFD capable CA and a non-SBFD capable CA.

6. The communication apparatus according to claim 1, wherein the at least one RO is a separated RO that is usable only by a SBFD capable CA or a non-SBFD capable CA.

7. The communication apparatus according to claim 1 or 5, wherein the one or more ROs of the determined RO group are one or more shared ROs in non-SBFD symbols .

8. The communication apparatus according to claim 1 or 6, wherein the one or more ROs of the determined RO group are one or more separated ROs in non-SBFD symbols.

9. The communication apparatus according to claim 1, wherein the one or more ROs of the determined RO group are one or more ROs in SBFD symbols .

10. The communication apparatus according to claim 1 or 5, wherein the at least one RO of the one or more ROs of the determined RO group are in SBFD symbols, and the remaining of the one or more ROs of the determined RO group are shared ROs in non-SBFD symbols.

11. The communication apparatus according to claim 1 or 6, wherein the at least one RO of the one or more ROs of the determined RO group are in SBFD symbols, and the remaining of the one or more ROs of the determined RO group are separated ROs in non-SBFD symbols.

12. The communication apparatus according to claim 6, wherein the communication apparatus is the SBFD capable CA, and the preamble associated with the one or more ROs of the determined RO group is same as a preamble used for the non-SBFD capable CA.

13. The communication apparatus according to claim 5 or 6, wherein the communication apparatus is the SBFD capable CA, and the preamble associated with the one or more ROs of the determined RO group is different from a preamble used for the non-SBFD capable CA.

14. The communication apparatus according to any one of claims 1 to 3, wherein the circuitry is configured to determine a configuration period for the plurality of RO groups based on an earliest SBFD symbol of the plurality of RO groups in time domain.

15. The communication apparatus according to claim 2 or 3, wherein the circuitry is configured to determine a configuration period for the plurality of RO groups based on an offset period between the configuration period for the plurality of RO groups and a configuration period of the non-SBFD capable communication apparatus (CA), the offset period being determined by a communication device.

16. The communication apparatus according to any one of claims 1-15, wherein the circuitry is configured to determine the plurality of RO groups based on a search procedure starting from a virtual RO being located at a lowest frequency resource of a plurality of ROsin both SBFD symbols and non-SBFD symbols, wherein the plurality of ROs being configured by a communication device or specified in technical specifications.

17. The communication apparatus according to any one of claims 1-15, wherein the circuitry is configured to determine the plurality of RO groups based on a search procedure starting from a first frequency resource or resource index, the first frequency resource or resource index being different from each of a plurality of second frequency resources or indexes at which a plurality of ROs in SBFD symbols are located.

18. A communication device comprising: a transmitter, which in operation, transmits control information relating to a random access channel occasion (RO) group of a plurality of RO groups used for multiple Physical Random Access Channel (PRACH) transmissions, each of the plurality of RO groups including one or more ROs; and a receiver, which in operation, receives a preamble on the one or more ROs of the RO group, wherein the one or more ROs include at least one RO in subband non-overlapping full duplex (SBFD) symbols or at least one RO in non-SBFD symbols.

19. A communication method implemented by a communication apparatus, comprising: determining a random access channel occasion (RO) group from a plurality of RO groups for multiple Physical Random Access Channel (PRACH) transmissions, each of the plurality of RO groups including one or more ROs; and transmitting a preamble on the one or more ROs of the determined RO group, wherein the one or more ROs include at least one RO in subband non-overlapping full duplex (SBFD) symbols or at least one RO in non-SBFD symbols.

20. A communication method implemented by a communication device, comprising: transmitting control information relating to a random access channel occasion (RO) group of a plurality of RO groups used for multiple Physical Random Access Channel (PRACH) transmissions, each of the plurality of RO groups including one or more ROs; and receiving a preamble on the one or more ROs of the RO group, wherein the one or more ROs include at least one RO in subband non-overlapping full duplex (SBFD) symbols or at least one RO in non-SBFD symbols.

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