RO group resources for multi-PRACH transmission

Abstract

The present disclosure provides a communications apparatus and a communications method for RO group resources for multi-PRACH transmissions, the communications apparatus including: a circuit configured to, upon operation, determine at least one first RO group including a plurality of Random Access Channel (RACH) opportunities (ROs) corresponding to a plurality of PRACH transmissions in a multi-PRACH transmission from the communications apparatus; and a transmitter configured, upon operation, to transmit a preamble in each of the plurality of ROs of the at least one first RO group.

Description

[Technical Field]

[0001] The present disclosure relates to a communications apparatus and method for Random Access Channel (RACH) Opportunity (RO) group resources for multi-Physical Random Access Channel (multi-PRACH) transmissions. [Background technology]

[0002] A new Working Item (WI) for New Radio (NR) Coverage Enhancement (CovEnh) was approved in Release 18, and one of its main objectives is to specify PRACH coverage extensions (RAN1, RAN2) including multiple PRACH transmissions using the same beam for a 4-step RACH procedure, and, if justified, PRACH transmissions for a 4-step RACH procedure using different beams. The latest RAN agreements agree that at least ROs located at different time instances can be used for multiple PRACH transmissions, and that multiple PRACH transmissions can be distinguished from a single PRACH transmission.

[0003] However, there has been no discussion yet on a communication device and a communication method regarding RO group resources for multi-PRACH transmission to improve coverage performance.

[0004] Therefore, there is a need for a communication apparatus and a communication method that provide a feasible technical solution for RO group resources for multi-PRACH transmission to achieve improved coverage performance with achievable gains from combining preamble detection utilizing time diversity and / or frequency diversity. Furthermore, other desirable features and characteristics will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings and the background technology of this disclosure. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] 3GPP TS 38.300 v16.3.0 [Non-patent document 2] 3GPP TS 38.211 v16.3.0 [Non-patent document 3] 3GPP TS 23.502 [Non-patent document 4] 3GPP TS 23.122 [Non-patent document 5] ITU-R M.2083 [Non-patent document 6] 3GPP TS 23.287 v16.4.0 Summary of the Invention

[0006] The non-limiting embodiments contribute to providing a communication device and a communication method regarding RO group resources for multi-PRACH transmission.

[0007] According to a first embodiment of the present disclosure, there is provided a communication device comprising: a circuit for determining, during operation, at least one first RO group including a plurality of Random Access Channel (RACH) opportunities (ROs) corresponding to a plurality of multi-Physical Random Access Channel (multi-PRACH) transmissions in a multi-PRACH transmission from the communication device; and a transmitter for transmitting, during operation, a preamble in each of a plurality of ROs of the at least one first RO group.

[0008] According to a second embodiment of the present disclosure, a base station includes: a circuit that, during operation, generates a signal including information of at least one first random access channel (RACH) opportunity (RO) group including a plurality of RACH opportunities (ROs) corresponding to a plurality of multi-PRACH transmissions in a multi-physical RACH (PRACH) transmission from a communication device; a transmitter that, during operation, transmits the signal to the communication device; and a receiver that, during operation, receives at least one multi-PRACH transmission corresponding to the at least one first RO group from the communication device, wherein the circuit detects a preamble in each of the at least one multi-PRACH transmission.

[0009] According to a third embodiment of the present disclosure, a communication method includes: determining at least one first RO group including a plurality of Random Access Channel (RACH) Opportunities (ROs) corresponding to a plurality of PRACH transmissions in a multi-PRACH transmission from a communication device; and transmitting a preamble in each of the plurality of ROs of the at least one first RO group.

[0010] It should be noted that the general or specific embodiments may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any selective combination thereof.

[0011] Further advantages and benefits of an embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features.

[0012] Embodiments of the present disclosure, by way of example only, will be better understood and readily apparent to those skilled in the art from the following description and in conjunction with the drawings in which: [Brief explanation of the drawings]

[0013] [Figure 1]FIG. 1 illustrates an example architecture of a 3GPP NR radio access network (NR-RAN) to which exemplary embodiments of the present disclosure may be applied. [Figure 2] 1 is a schematic diagram illustrating the division of functions between an NG-RAN and a 5G Core Network (5GC) to which exemplary embodiments of the present disclosure are applied; [Figure 3] FIG. 1 is a sequence diagram of a radio resource control (RRC) connection setup / reconfiguration procedure to which an exemplary embodiment of the present disclosure is applied. [Figure 4] 1 is a schematic diagram illustrating 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 are applied. [Figure 5] FIG. 1 is a block diagram illustrating an example 5G system architecture for V2X communications in a non-roaming scenario to which example embodiments of the present disclosure may be applied. [Figure 6] FIG. 1 is an example diagram of different random access channel (RACH) opportunity (RO) user equipment (UE) groups in accordance with various embodiments of the present disclosure. [Figure 7] Table showing an exemplary list of possible embodiments according to the present disclosure [Figure 8] 10A-10C illustrate example determinations of different RO UE groups for different numbers of PRACH transmissions assuming only separate ROs are used for multi-PRACH transmissions, in accordance with various embodiments of the present disclosure. [Figure 9] 10A-10C illustrate exemplary determination of different RO UE groups for different numbers of PRACH transmissions, assuming both separate and shared ROs are used for multi-PRACH transmissions, according to various embodiments of the present disclosure. [Figure 10]1 is an example diagram of explicit notification in a Master Information Block or System Information Block (MIB / SIB) according to various embodiments of the present disclosure. [Figure 11] 1 is an illustrative diagram of an explicit notification in tabular form according to various embodiments of the present disclosure; [Figure 12] 1 is an illustrative diagram of another explicit notification in tabular format according to various embodiments of the present disclosure. [Figure 13] 1 is an illustrative diagram of determining multiple RO cell groups by clustering one or more ROs that are closely located in the time domain, according to various embodiments of the present disclosure. [Figure 14] 1 is an illustrative diagram of determining multiple RO cell groups by clustering one or more ROs located in the same time unit, according to various embodiments of the present disclosure. [Figure 15] 1 is an illustrative diagram of determining multiple RO cell groups by clustering one or more ROs that are closely located in the frequency domain, according to various embodiments of the present disclosure. [Figure 16] 1 is an illustrative diagram of determining multiple RO cell groups by clustering one or more ROs located in the same frequency resource allocation in the frequency domain, according to various embodiments of the present disclosure. [Figure 17] 1 is an illustrative diagram of determining multiple RO cell groups by clustering one or more ROs that are closely located in the frequency and time domains, according to various embodiments of the present disclosure. [Figure 18] 1 is an illustration of an exemplary (pre)configured RO cell group according to various embodiments of the present disclosure. [Figure 19] 1 is a flowchart of a UE according to various embodiments of the present disclosure; [Figure 20] 1 is a flowchart illustrating a communication method according to various embodiments. [Figure 21] 1 is a schematic block diagram of an exemplary communication device in accordance with various embodiments; [Figure 22] 1 is a schematic block diagram of another exemplary communication device according to various embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0014] Those skilled in the art will appreciate that the elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures, block diagrams, or flowcharts may be exaggerated relative to other elements to help improve understanding of the embodiments.

[0015] Some embodiments of the present disclosure will now be described, by way of example only, with reference to the drawings in which like reference numbers and letters indicate similar or equivalent elements.

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

[0017] The user plane protocol stack in NR (see, for example, Section 4.4.1 of Non-Patent Document 1) includes a PDCP (Packet Data Convergence Protocol) sublayer, an RLC (Radio Link Control) sublayer, and a MAC (Medium Access Control) sublayer, which are terminated at the gNB on the network side. In addition, a new access stratum (AS) sublayer (SDAP, Service Data Adaptation Protocol) is introduced above PDCP (see, for example, Section 6.5 of Non-Patent Document 1). NR also defines a control plane protocol stack (see, for example, Section 4.4.2 of Non-Patent Document 1). An overview of Layer 2 functions is provided in Section 6 of Non-Patent Document 1. The functions of the PDCP, RLC, and MAC sublayers are described in Sections 6.4, 6.3, and 6.2 of 3GPP TS 2.0, respectively. The functions of the RRC layer are described in Section 7 of 3GPP TS 2.0. Furthermore, sidelink communication is introduced in 3GPP TS 2.0. The sidelink supports direct communication between UEs using sidelink resource allocation modes, physical layer signals / channels, and physical layer procedures (see, for example, Section 5.7 of 3GPP TS 2.0).

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

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

[0020] NR use cases / deployment scenarios include enhanced mobile broadband (eMBB), ultra-reliable and low-latency communications (URLLC), and / or massive machine-type communications (mMTC), which have diverse requirements for data rates, latency, and coverage. For example, eMBB is expected to support peak data rates (20 Gbps downlink and 10 Gbps uplink) and user-perceived data rates on the order of three times those offered by IMT-Advanced. In contrast, URLLC has more stringent requirements, including extremely low latency (user plane latency of 0.5 ms for UL and DL, respectively) and high reliability (1-10 Mbps within 1 ms). -5 Finally, mMTC preferably requires high connection density (1,000,000 devices / km in urban environments). 2 ), wide coverage in adverse environments, and extremely long battery life (15 years) for low-cost devices may be desired.

[0021] Therefore, an OFDM numerology (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) suitable for one use case may not work well for another use case. For example, low-latency services may preferably require a shorter symbol length (and therefore a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also called TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP length than scenarios with small delay spreads. To maintain a similar CP overhead, the subcarrier spacing should be optimized depending on the delay spread. In NR, more than one value of subcarrier spacing may be supported. Therefore, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, etc. are currently considered. The symbol length T u and the subcarrier spacing Δf is given by the formula Δf=1 / Tu As in LTE systems, the term "resource element" can be used to denote the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0022] In the new wireless system 5G-NR, a resource grid of subcarriers and OFDM symbols is defined for each numerology and carrier in the uplink and downlink. Each element of the resource grid is called a resource element and is identified based on a frequency index in the frequency domain and a symbol position in the time domain (see Non-Patent Document 2).

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

[0024] In particular, the gNB and ng-eNB handle the following key functions: Radio Resource Management functions such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, dynamic allocation (scheduling) of resources to UEs in both uplink and downlink; - IP header compression, encryption, and integrity protection of data; - AMF selection at UE attach time when routing to an AMF cannot be determined from information provided by the UE; - Routing of user plane data towards UPF; - Routing of control plane information towards AMF; - setting up and tearing down connections; - scheduling and sending of paging messages; - Scheduling and transmission of system broadcast information (AMF or OAM origin); - setting up measurements and measurement reporting for mobility and scheduling; - Transport-level packet marking in the uplink; - Session management; - Support for network slicing; - QoS flow management and mapping to data radio bearers; - Support for UEs in RRC_INACTIVE state; - Non-Access Stratum (NAS) message delivery function; - Sharing of radio access networks; - Dual connectivity; - Close collaboration between NR and E-UTRA.

[0025] The Access and Mobility Management Function (AMF) handles the following main functions: - Terminating Non-Access Stratum (NAS) signaling; - NAS signaling security; - Access Stratum (AS) security control; - 3GPP Core Network (CN) inter-node signaling for mobility between access networks; - Reachability to idle mode UEs (including control and execution of paging retransmissions); - Managing the registration area; - Support for intra-system and inter-system mobility; - Access authentication; - Access authorization, including checking roaming privileges; - Mobility management control (subscription and policy); - Support for network slicing; - Select the Session Management Function (SMF).

[0026] Furthermore, the User Plane Function (UPF) handles the following main functions: - anchor points for intra-RAT mobility / inter-RAT mobility (if applicable); - External PDU (Protocol Data Unit) session points for interconnection with data networks; - packet routing and forwarding; - Packet inspection and policy rule enforcement for the user plane; - Traffic usage reporting; - uplink classifier that supports routing of traffic flows to the data network; - Branching Point to support multi-homed PDU sessions; - QoS processing for the user plane (e.g., packet filtering, gating, UL / DL rate enforcement); - Uplink traffic validation (mapping of SDF to QoS flows); - Downlink packet buffering and downlink data notification triggering functions.

[0027] Finally, the Session Management Function (SMF) handles the following major functions: - Session management; - IP address allocation and management for UE; - Selection and control of UPF; - The ability to configure traffic steering in the User Plane Function (UPF) to route traffic to the appropriate destination; - Policy enforcement and QoS in the control section; - Notification of downlink data.

[0028] The sequence diagram 300 in Figure 3 shows some of the interactions between the UE, gNB, and AMF (5GC entity) when the UE transitions from RRC_IDLE to RRC_CONNECTED in the NAS part (see Non-Patent Document 1). The transition steps are as follows:

[0029] 1. The UE requests to set up a new connection from the RRC_IDLE state. 2 / 2a. The gNB completes the RRC setup procedure. Note: Scenarios in which the gNB rejects the request are described below. 3. The first NAS message from the UE, sent piggyback in RRCSetupComplete, is sent to the AMF. 4 / 4a / 5 / 5a. Additional NAS messages may be exchanged between the UE and the AMF, see reference

[22] of 3GPP TS 2013-01-11 ("Non-Access Stratum (NAS) Functions Associated with Mobile Station in Idle Mode"). 6. The AMF prepares and sends UE context data (including PDU session context, security keys, UE radio capabilities, and UE security capabilities, etc.) to the gNB. 7 / 7a. The gNB activates AS security with the UE. 8 / 8a. The gNB performs reconfiguration to set up SRB2 and DRB. 9. The gNB notifies the AMF that the setup procedure is complete.

[0030] RRC is a higher layer signaling protocol used to configure the UE and the gNB. Specifically, in this transition, the AMF creates UE context data (including, for example, PDU session context, security keys, UE radio capabilities, and UE security capabilities) and sends it to the gNB via an INITIAL CONTEXT SETUP REQUEST. The gNB then activates AS security with the UE by sending a SecurityModeCommand message to the UE, and the UE responds with a SecurityModeComplete message. The gNB then performs reconfiguration to establish signaling radio bearer 2 (SRB2) and data radio bearers (DRBs) by sending an RRCReconfiguration message to the UE and receiving an RRCReconfigurationComplete message from the UE in response. For signaling-only connections, the RRCReconfiguration step is omitted because SRB2 and DRBs are not set up. Finally, the gNB notifies the AMF that the establishment procedure is complete via an INITIAL CONTEXT SETUP RESPONSE.

[0031] The schematic diagram 400 in Figure 4 illustrates several use cases for 5G NR. The 3GPP NR (3rd Generation Partnership Project New Radio) considers three use cases envisioned for IMT-2020 to support a wide variety of services and applications. Phase 1 technical specifications for enhanced mobile broadband (eMBB) have been finalized. Current and future work includes standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC), in addition to further extending eMBB support. Figure 4 illustrates some examples of IMT usage scenarios envisioned for 2020 and beyond (see, for example, Figure 2 in Non-Patent Document 5).

[0032] URLLC use cases have stringent requirements for capabilities such as throughput, latency, and availability, and are envisioned as one of the enablers for future vertical applications, such as wireless control of industrial manufacturing or production processes, remote medical surgery, power distribution automation in smart grids, and transportation safety. URLLC's ultra-high reliability is supported by identifying technologies to meet the requirements set by TR 38.913. For NR URLLC in Release 15, key requirements include a user plane target latency of 0.5 ms for the uplink (UL) and 0.5 ms for the downlink (DL). A typical URLLC requirement for a single packet transmission is a block error rate (BLER) of 1E-5 for a 32-byte packet size with a 1-ms user plane latency.

[0033] From a physical layer perspective, there are several possible ways to improve reliability. Current scope for improving reliability includes defining a separate CQI table for URLLC, a more compact DCI format, PDCCH repetition, etc. However, as NR becomes more stable and developed (a key requirement for NR URLLC), the scope for achieving ultra-high reliability may expand. Specific use cases for NR URLLC in Release 15 include augmented reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0034] Furthermore, technology enhancements targeted at NR URLLC target latency improvement and reliability enhancement. Technology enhancements for latency improvement include configurable numerology, minislot-based scheduling with flexible mapping, grant-free (configured grant) uplink, minislot-level repetition in the data channel, and preemption in the downlink. Preemption means that a transmission for which resources have already been allocated is aborted and the allocated resources are used for another transmission requested later with smaller latency / higher priority requirements. Thus, a previously granted transmission is preempted by a later transmission. Preemption applies regardless of the specific service type. For example, a transmission of service type A (URLLC) can be preempted by a transmission of service type B (e.g., eMBB). Technology enhancements for reliability improvement include dedicated channel quality indicator (CQI) / modulation and coding scheme (MCS) tables for a target BLER of 1E-5.

[0035] The mMTC (Massive Machine Type Communication) use case is characterized by a very large number of connected devices transmitting relatively small amounts of data that are generally latency sensitive. The devices need to be low cost and have extremely long battery life. From an NR perspective, utilizing very narrow bandwidth portions is one possible solution to achieve power savings from the UE perspective, enabling long battery life.

[0036] As mentioned above, it is expected that the reliability range in NR will expand. One key requirement for all cases, especially for URLLC and mMTC, is high or ultra-high reliability. Several mechanisms can be considered to improve reliability from a radio perspective and a network perspective. In general, there are several key areas that can help improve reliability. These areas include compact control channel information, data channel / control channel repetition, and diversity related to the frequency, time, and / or spatial domains. These areas are generally applicable to reliability, regardless of the specific communication scenario.

[0037] Additional use cases with more stringent requirements are envisioned for NR URLLC, such as factory automation, transportation, and power distribution. The more stringent requirements include higher reliability (up to 10 times faster), depending on the use case. -6 level), higher availability, packet size up to 256 bytes, time synchronization on the order of a few microseconds (values ​​range from 1 to a few microseconds depending on the frequency range), and short latency on the order of 0.5 to 1 ms (target latency for the user plane in particular is 0.5 ms).

[0038] Furthermore, for NR URLLC, several technology enhancements are possible from the perspective of the physical layer. In particular, enhancements related to the PDCCH (Physical Downlink Control Channel) include compact DCI, PDCCH repetition, and increased PDCCH monitoring. Also, enhancements related to the UCI (Uplink Control Information) include HARQ (Hybrid Automatic Repeat Request) enhancements and CSI feedback enhancements. Also, PUSCH enhancements related to minislot-level hopping and retransmission / repetition are recognized. The term "minislot" refers to a transmission time interval (TTI) that contains fewer symbols than a slot (a slot comprises 14 symbols).

[0039] The 5G Quality of Service (QoS) model is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (GBR QoS flows) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flows). Therefore, at the NAS level, QoS flows are the finest granularity of QoS differentiation in a PDU session. Within a PDU session, QoS flows are identified by a QoS Flow ID (QFI) carried in the encapsulation header over the NG-U interface.

[0040] The 5GC establishes one or more PDU sessions for each UE. The NG-RAN establishes at least one Data Radio Bearer (DRB) for each UE along with the PDU session, and can then configure additional DRBs for the QoS flows of that PDU session (as determined by the NG-RAN, e.g., as described 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 5GC associate UL and DL packets with QoS flows, and AS-level mapping rules in the UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0041] Block diagram 500 in Figure 5 illustrates the non-roaming reference architecture for 5G NR (see Section 4.2.1.1 of Non-Patent Document 6). Application Functions (AFs) (e.g., external application servers handling 5G services as exemplified in Figure 4) interact with the 3GPP Core Network to provide services. For example, they support application influence on traffic routing, access Network Exposure Functions (NEFs), or interact with a policy framework (see Policy Control Function (PCF)) for policy control (e.g., QoS control). Based on the operator's deployment, application functions (AFs) deemed trusted by the operator can be allowed to interact directly with the associated Network Functions. Application Functions not permitted by the operator to directly access Network Functions interact with the associated Network Functions using an external exposure framework via the NEF.

[0042] Figure 5 further illustrates additional 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 5G, as well as the V2X Application Server (V2AS) and Data Network (DN; e.g., operator-provided services, internet access, or third-party services). All or part of the core network functions and application services may be located and run in a cloud computing environment.

[0043] The latest RAN agreement has agreed that at least ROs located at different time instances can be used for multiple PRACH transmissions, and that multiple PRACH transmissions can be distinguished from a single PRACH transmission, but much work remains to be done (FFS: For Further Study). RAN1#110-bis-e has agreed that, for multiple PRACH transmissions using the same beam, at least ROs located at different time instances can be used for transmission. For example, for a UE with multiple transmit (Tx) chains, it is still unclear whether or how the starting resource block (RB) of the RO for multiple PRACH transmissions differs between different time instances, and whether multiple PRACH transmissions can be located at the same time instance. Furthermore, RAN1#111 has agreed that one or more of the following options can be considered to distinguish multiple PRACH transmissions using the same Tx beam from a single PRACH transmission. In the first option, multiple PRACHs can be transmitted in a shared RO using separate preambles. In the second option, multiple PRACHs can be transmitted in separate ROs. In a third option, some of the PRACHs may be transmitted in a shared RO with separate preambles, and other PRACHs may be transmitted in separate ROs. Other options are not excluded. Shared RO / shared preamble or separate RO / separate preamble means shared with or separate from a single PRACH transmission, respectively.

[0044] How multiple RACH opportunities (ROs) for a specific number of multi-PRACH transmissions are determined is not specified, and at least one of the following conditions is considered: (1) Multi-PRACH transmissions can be performed in separate ROs or in shared ROs with separate preambles, where shared RO / shared preamble or separate RO / separate preamble means shared with a single PRACH transmission or separate from a single PRACH transmission, respectively; (2) Frequency domain resource allocations for multiple ROs can be the same or different; and (3) Multiple ROs located at different time instances can be used.

[0045] In the present disclosure, a UE may be configured to determine at least one RO UE group, for example, including a number of ROs for N specific PRACH transmissions that may be transmitted in one PRACH attempt, where N is greater than or equal to one. One preamble may be transmitted in each of the N ROs of the at least one RO UE group. The at least one RO UE group may be associated with one or more synchronization signal block (SSB) indices or may be associated with at least two SSB indices. For example, referring to illustration 600 of FIG. 6, different RO UE groups 602, 604, 606, 608, 610, and 612 are depicted, and each RO UE group may include two or four ROs for two or four specific PRACH transmissions, respectively, that are transmitted in one PRACH attempt. RO UE group 602 is associated with SSB#2, RO UE group 604 is associated with SSB#0, RO UE group 606 is associated with SSB#2, RO UE group 608 is associated with SSB#0, RO UE group 610 is associated with SSB#1 and SSB#3, and RO UE group 612 is associated with SSB#1 and SSB#3. Furthermore, at least one RO UE group may be associated with one or more Channel State Information Reference Signal (CSI-RS) indices if a CSI-RS-based beam is used to transmit a preamble on each of the N ROs of at least one RO UE group. The CSI-RS-based beam is configured in the UE by the gNB. A RO UE group is defined corresponding to a multi-PRACH transmission from a UE and may include multiple ROs corresponding to multiple PRACH transmissions in the multi-PRACH transmission. The multiple ROs in a RO UE group may be the same as or different from the multiple ROs included in another RO UE group used by another communication device. It is understood that a "RO UE group" may also be referred to herein as a "RO communication device group," a "first RO group," an "RO bundle," or an "RO bundling."

[0046] The N ROs may be separate or shared ROs, each separated from a single PRACH transmission. The current SSB-to-RO mapping for the N ROs can be reused, or a new SSB-to-RO mapping sequence for the N ROs can be used (e.g., a cyclic shift mapping for N ROs for L SSBs, where L is equal to or greater than 1, or an SSB-to-RO UE group mapping). Advantageously, better performance gains in coverage can be achieved due to the gains achievable by combining preamble detection with time and / or frequency diversity. The current SSB-to-RO mapping can be configured by the higher layer parameter ssb-perRACH-OccasionAndCB-PreamblesPerSSB, which conveys information about the number of SSBs mapped to each RO and the number of random access preambles mapped to each SSB.

[0047] The UE may be configured to determine at least one RO UE group including N ROs based on the following operations. For example, the at least one RO UE group may be determined from M RO cell groups (M is greater than or equal to 1) to utilize time diversity and / or frequency diversity (e.g., determining at least one RO UE group) based on one of the following options: In the first option, random selection is used; In the second option, explicit notification is used; In the third option, implicit notification by rule is used. In some implementations, the UE may be configured to determine at least one RO UE group from multiple ROs (e.g., from a pool of ROs available for multiple PRACH transmissions) regardless of the RO cell group, for example, when no RO cell group is defined. The RO cell group may include one or more ROs used among one or more UEs or communication devices. The one or more RO cell groups may be commonly determined in the serving cell. It will be understood that a "RO cell group" may also be referred to herein as a "second RO group." An RO cell group is a type of cell-specific group within a serving cell, and at least one RO UE group is a type of UE-specific group within the serving cell.

[0048] Furthermore, at least one RO UE group may be determined using ROs located at the same or different time instances, at least one RO UE group may be determined using ROs located at the same or different frequency allocation indices, or at least one RO UE group may be determined using ROs located at different time and frequency indices.

[0049] To determine the RO cell group, if M=1, one RO cell group may be determined by including all ROs available for multiple PRACH transmissions. If M>1, each of the M RO cell groups may be determined based on one of the following methods 1 to 5: (Method 1) by clustering one or more ROs located closely in the time domain; (Method 2) by clustering one or more ROs located in the same time unit including the same slot / subframe / frame or the same period of the configuration for a specific number of multiple PRACH transmissions; (Method 3) by clustering one or more ROs located closely in the frequency domain; (Method 4) by clustering one or more ROs located in the same frequency resource allocation; or (Method 5) by clustering one or more ROs located closely in the frequency and time domains. One or more ROs may be separated or shared from a single PRACH transmission. Each of the one or more ROs in the above methods 1 to 5 may have a specific time and frequency resource allocation. On the gNB side, the gNB may be configured to receive N PRACH transmissions and perform combined detection of the preambles. Methods 1-5 above are further described in Figures 8-18 of the present disclosure.

[0050] FIG. 7 shows a table 700 providing an exemplary list of possible embodiments according to the present disclosure. For example, when M=1 (see table entry 702), the embodiment may be based on one of the three options described above for determining at least one RO UE group (e.g., in the first option, random selection is used; in the second option, explicit notification is used; and in the third option, implicit notification by rule is used). In FIG. 6, only one RO cell group (M=1) is assumed. When M>1 (see table entry 704), the embodiment is a combination of an option for determining at least one RO UE group (e.g., one of the three options described above) and a method for determining an RO cell group (e.g., methods 1-5 described above), which are further described in FIGS. 8-18 of the present disclosure.

[0051] Combining one option for determining at least one RO UE group with one method for determining an RO cell group results in many possibilities. Figure 8 shows an example 800 of determining different RO UE groups (e.g., RO UE groups 802, 804, 806, 808, 810, and 812) for different numbers of PRACH transmissions, assuming that only separate ROs are used for multiple PRACH transmissions. In this example, each RO cell group (e.g., RO UE cell groups 814, 816, 818, and 820) can be determined by clustering one or more ROs that are closely located in the time domain (e.g., Method 1 using frequency division multiplexed ROs (FDMed ROs) located at one time instance) or by clustering one or more ROs that are located in the same slot by Method 2. 9 illustrates the determination of different RO UE groups for different numbers of PRACH transmissions, and assumes that both separate ROs (e.g., the ROs shown at reference 902) and shared ROs (e.g., the ROs shown at reference 904) are used for multi-PRACH transmissions, and multiple PRACHs are transmitted using separate preambles in the shared ROs. In FIG. 9, there are four RO UE groups #0-#3 for two PRACH transmissions, and two RO UE groups #4-#5 for four PRACH transmissions, and the ROs of each of these six RO UE groups are time-division multiplexed ROs (TDMed ROs) and located in the same frequency allocation.

[0052] The UE may be configured to determine at least one RO UE group including N ROs for N specific PRACH transmissions transmitted in one PRACH attempt based on one of the three options above. The N PRACH transmissions may be referred to as multiple PRACH transmissions, multi-PRACH transmissions, or one PRACH attempt. If the UE is capable of multi-PRACH transmissions, the UE may perform N PRACH transmissions based on the ROs in the RO UE group in one PRACH attempt, and this one PRACH attempt may be referred to as a process of performing N PRACH transmissions. On the gNB side, the gNB may receive the N PRACH transmissions and perform combined detection of the preamble. In the first option, at least one RO UE group may include N ROs determined by the UE from M RO cell groups based on random selection to utilize time and / or frequency diversity. Regarding the M RO cell groups, two cases are possible: (Case 1) There is a common understanding of M RO cell groups among UEs in the serving cell, and the gNB needs to receive N PRACH transmissions and perform blind detection of preambles. (Case 2) There is no common understanding of M RO cell groups among UEs in the serving cell, and the gNB also needs to receive N PRACH transmissions and perform blind detection of preambles from the N PRACH transmissions, but this requires more effort from the gNB's perspective than Case 1. Since the UE can randomly determine N ROs from M RO cell groups, multiple RO UE groups can be introduced so that increasing the random perspective is beneficial from the perspective of the random access procedure.

[0053] In a second option, at least one RO UE group may include N ROs determined from the M RO cell groups based on explicit notification by the UE to achieve time diversity gain and / or frequency diversity gain. The explicit notification may be a higher layer parameter that can be included in a Master Information Block (MIB) or System Information Block (SIB). For example, referring to the example MIB / SIB 1000 in FIG. 10 , a Multi_PRACH_transmission_R18 (see reference numeral 1002) is included in the MIB / SIB, and indicates a preamble format RO_UE_Group (reference 1004) corresponding to two / four / six / eight PRACH transmissions, a starting slot of the RO_UE_Group (reference 1006), and the position and length of the ROs within the RO_UE_Group in the time and frequency domains (reference 1008).

[0054] Alternatively, the explicit notification may be in the form of a table. A new table with new entries added or an existing random access configuration table (e.g., Table 6.3.3.2-3 in Non-Patent Document 2) may be used to indicate at least one RO UE group for multi-PRACH transmission. When the new table is used, a new upper layer parameter may be introduced to indicate a row in the table corresponding to at least one RO UE group including N ROs. The new table may be configured or pre-configured. Figure 11 shows an example of a new table 1100 that explicitly indicates different RO UE groups for different numbers of multi-PRACH transmissions (N). The entries for the N ROs are based on Figure 6.

[0055] If an existing table with the new entries added is used, the current higher layer parameter prach-ConfigurationIndex can be reused to indicate a row in the table corresponding to at least one RO UE group containing N ROs. Figure 12 shows an example table 1200, which is table 6.3.3.2-3 of 3GPP TS 2013-01-01 10:29 Page 12 of 10, extended with a new entry indicating the RO for multi-PRACH transmission (see reference numeral 1202 indicating the RO for multi-PRACH transmission with N=2 and N=4). The existing table with the newly added entries can be configured or pre-configured.

[0056] Furthermore, in a third option, at least one RO UE group may include N ROs determined by the UE from M RO cell groups for utilizing time diversity and / or frequency diversity. The implicit notification may be based on a cyclic shift or the order of sequences. As an example, the UE may make a selection via the sequence ((i mod M)=k) and may be set to obtain an RO from the RO cell group #k among the M RO cell groups (0≦i<N, 0≦k<M). In another example, as an implicit notification, the (i + 1)-th RO in at least one RO UE group associated with the logical (i + 1)-th index of the PRACH time / frequency resources from the M RO cell groups in the resource pool is determined by the UE (0≦i<N). Here, the resource pool is composed of consecutive physical resource blocks (PRBs) and consecutive or non-consecutive logical slots for a plurality of multi-PRACH transmissions (determined, for example, before mapping to physical resources). The logical (i + 1)-th index of the PRACH time / frequency resources can be defined based on the order: first, in ascending order of the frequency resource index of the frequency multiplexed PRACH opportunities; second, in ascending order of the time resource index of the time multiplexed PRACH opportunities within the logical PRACH slot; and third, in ascending order of the index of the logical PRACH slot. It is understood that the formula for implicit notification is not limited to the formula described in the above examples and other variations are possible.

[0057] In another example, as an implicit notification, the UE determines the (i+1)-th RO (0≦i<N) within at least one RO UE group associated with the same logical index of the preamble from M RO cell groups within a resource pool. This resource pool is composed of consecutive PRBs and consecutive or non-consecutive logical slots for a plurality of multi-PRACH transmissions (e.g., before mapping to physical resources). If the number of ROs having the same logical index of preamble K is less than N and K is 1 or more, the following splitting method can be used. First, it is determined such that K ROs are associated with the first logical index of the preamble. Next, it is determined such that (N-K) ROs are associated with the second logical index of the preamble. For example, assuming that an RO cell group with M=1 includes four ROs (RO#0 to RO#3) associated with the first logical index of the preamble and five ROs (RO#4 to RO#8) associated with the second logical index of the preamble before being mapped to physical resources, the UE can be notified to perform two PRACH transmissions. In this case, when the UE selects two ROs (RO#0, RO#1) associated with the first logical index of the preamble to perform two PRACH transmissions, or when performing six PRACH transmissions, the UE can select four ROs (RO#0 to RO#3) associated with the first logical index of the preamble and two ROs (RO#4, RO#5) associated with the second logical index of the preamble to perform six PRACH transmissions. In this case, two different preambles can be used. As an advantage, this can avoid an increase in signaling overhead.

[0058] FIG. 13 illustrates an example 1300 for determining two RO cell groups (e.g., RO cell groups 1302 and 1304) by clustering one or more ROs that are closely located in the time domain in accordance with various embodiments of the present disclosure (e.g., based on Method 1, in which each of M RO cell groups can be determined by clustering one or more ROs that are closely located in the time domain). Four RO UE groups (e.g., RO UE groups 1306, 1308, 1310, 1312) can be obtained by any of Options 1, 2, or 3. One or more ROs can be FDMed ROs at one time instance and can be closely located within Z ms of time. For example, Z=1 ms in FIG. 13. Within an RO cell group, one or more ROs can have different frequency resource allocations. Advantageously, this method is suitable when the overall RO density varies in the time domain. When an RO UE group includes N ROs from different RO cell groups, time diversity gain can be utilized. In FIG. 13, there are four RO UE groups #0 to #3 for four PRACH transmissions, and the ROs in each of these four RO UE groups are time-division multiplexed ROs (TDMed ROs) in the time domain and are allocated to the same frequency allocation.

[0059] Furthermore, in Figure 13, for two PRACH transmissions, a RO UE group can include two ROs associated with the same SSB-based beam, such as RO UE group #5 including RO #0 and RO #4, or RO UE group #6 including RO #8 and RO #12. As mentioned above, there is a time gap between RO UE group #5 and RO UE group #6 due to the difference in overall RO density in the time domain. It is beneficial to minimize the complexity of the gNB's preamble detection or to conserve memory for performing preamble detection. From the gNB's perspective, if there are a large number of UEs capable of multi-PRACH transmissions in the serving cell attempting to access the network, the gNB's payload processing can be significantly reduced. This is because the gNB can perform combined detection processing of the preambles transmitted in RO UE group #5 during the time gap.

[0060] FIG. 14 illustrates an example 1400 for determining four RO cell groups (e.g., RO cell groups 1402, 1404, 1406, and 1408) by clustering one or more ROs located in the same time unit according to various embodiments of the present disclosure (e.g., based on Method 2, in which each of M RO cell groups can be determined by clustering one or more ROs located in the same time unit, including the same slot / subframe / frame or the same periodicity of the configuration for a specific number of PRACH transmissions). Within an RO cell group, one or more ROs may have different radio resource allocations. Furthermore, four RO UE groups (e.g., RO UE groups 1410, 1412, 1414, and 1416) may be obtained by any of Options 1, 2, or 3. In FIG. 14, there are four RO UE groups #0 to #3 for four PRACH transmissions, and each RO in these four RO UE groups is a time-division multiplexed RO (TDMed RO) in the time domain and is located in the same frequency allocation.

[0061] FIG. 15 illustrates an example 1500 for determining two RO cell groups (e.g., RO cell groups 1502 and 1504) by clustering one or more ROs that are closely located in the frequency domain in accordance with various embodiments of the present disclosure (e.g., based on Method 3, in which each of M RO cell groups can be determined by clustering one or more ROs that are closely located in the frequency domain). The one or more ROs may be closely located within a set of physical resource blocks (PRBs) in the frequency domain. For example, a set 1514 of two PRBs (e.g., PRB#0 and PRB#1) for RO cell group 1502 and a set 1516 of two PRBs (e.g., PRB#15 and PRB#16) for RO cell group 1504. In each of RO cell groups 1502 and 1504, one or more ROs may have different radio resource allocations. Furthermore, four RO UE groups (e.g., RO UE groups 1506, 1508, 1510, 1512) can be obtained by either option 1, 2, or 3. RO 1518 (e.g., RO#9 with SSB#1) in RO cell group 1502 is included in both RO UE groups 1508 and 1512. This method is suitable when the overall RO density varies in the frequency domain. When an RO UE group includes N ROs from different RO cell groups, frequency hopping gain can be utilized.

[0062] FIG. 16 illustrates an example for determining four RO cell groups (e.g., RO cell groups 1602, 1604, 1606, and 1608) by clustering one or more ROs located on the same frequency resource allocation in the frequency domain (e.g., based on Method 4, in which each of M RO cell groups can be determined by clustering one or more ROs located on the same frequency resource allocation in the frequency domain), according to various embodiments of the present disclosure. In each of RO cell groups 1602, 1604, 1606, and 1608, one or more ROs can have different time resource allocations. Furthermore, the four RO UE groups (e.g., RO UE groups 1610, 1612, 1614, and 1616) can be obtained by any of Options 1, 2, or 3. RO 1618 of RO cell group 1606 (e.g., RO #10 with SSB #2) is included in both RO UE groups 1614 and 1616. Advantageously, frequency hopping gains can be utilized when an RO UE group includes N ROs from different RO cell groups.

[0063] FIG. 17 illustrates an example 1700 for determining four RO cell groups (e.g., RO cell groups 1702, 1704, 1706, and 1708) by clustering one or more ROs that are adjacent in the frequency and time domains according to various embodiments of the present disclosure (e.g., based on Method 5, in which each of M RO cell groups can be determined by clustering one or more ROs that are adjacent in the frequency and time domains). For example, each of RO cell groups 1702, 1704, 1706, and 1708 is formed as a cluster or box (four ROs) having a size of Z ms in the time domain and a set of physical resource blocks (PRBs) in the frequency domain. Furthermore, four RO UE groups (e.g., RO UE groups 1710, 1712, 1714, and 1716) can be obtained by any of Options 1, 2, or 3. Advantageously, when multiple RO cell groups are available, it is possible to provide time diversity and frequency diversity gains when at least one RO UE group includes ROs from different RO cell groups.

[0064] In some implementations, if N exceeds the total number of ROs in the M RO cell groups, the UE may be configured to replicate one or more sets of M RO cell groups to meet the required number of ROs (e.g., N ROs). For example, assuming there are two RO cell groups, each with one RO, the UE needs to replicate one additional set of two RO cell groups for four PRACH transmissions.

[0065] In some implementations, an RO UE preamble group may be used to replace a UE cell group. An RO UE preamble group is defined as a group of one or more preambles dedicated to a UE that can be transmitted in multiple PRACH transmissions in one PRACH attempt by the UE. The UE determines N ROs for the multiple PRACH transmissions associated with the dedicated one or more preambles, and each of the dedicated one or more preambles is associated with at least one RO. Different RO UE preamble groups cannot be used for multiple PRACH transmissions in one PRACH attempt by the UE. It will be understood that a "RO UE preamble group" may also be referred to as a "RO communications device preamble group."

[0066] In one implementation, for a UE with multiple transmit (Tx) chains, the UE may be configured to determine at least one RO UE group for a particular number of multi-PRACH transmissions (e.g., N multi-PRACH transmissions) to be transmitted in one PRACH attempt for each of the multiple Tx chains, for example, based on one of the embodiments shown in table 700 of Figure 7. Each of the multiple Tx chains may be connected to one or more antennas, depending on the UE vendor's radio frequency chain design (e.g., Figure 22 shows one design possibility).

[0067] In some implementations, each of the M RO cell groups may be dedicated (pre-configured) for a specific number of multi-PRACH transmissions (e.g., N multi-PRACH transmissions). The UE may be configured to determine at least one RO UE group including N ROs from the corresponding dedicated RO cell group. Referring to example 1800 of FIG. 18 , it is assumed that there is a dedicated RO cell group 1804 for two PRACH transmissions and a dedicated RO cell group 1802 for four PRACH transmissions. Thus, for two PRACH transmissions, the UE determines two ROs from the corresponding dedicated RO cell group 1804. Similarly, for four PRACH transmissions, the UE determines four ROs from the corresponding dedicated RO cell group 1802.

[0068] In some implementations, the M RO cell groups may be determined based on cell-specific (pre-)configuration. Frequency hopping may be utilized within an RO UE group between ROs obtained from different RO cell groups (e.g., as shown in FIGS. 8, 14, and 15) or the same RO cell group (e.g., as shown in FIG. 16).

[0069] In some implementations, in all embodiments (e.g., as shown in table 700 of FIG. 7), there may be separate use cases, as follows: (Use Case 1) For example, as shown in FIGS. 6, 8, 9, 13, 14, and 17, an RO can be included in only one RO UE group. (Use Case 2) For example, as shown in FIGS. 15 and 16, an RO can be included in multiple RO UE groups. To improve the random perspective from the perspective of the random access procedure, the number of RO UE groups can be increased.

[0070] In some implementations, the same or different preambles may be transmitted in each of the N ROs of at least one RO UE group.

[0071] In one implementation, all embodiments (e.g., shown in table 700 of FIG. 7) are applicable to both the same-beam case and the different-beam case. In the same-beam case, the UE may be configured to use the same beam to transmit a specific number of multi-PRACH transmissions (e.g., N multi-PRACH transmissions). In the different-beam case, the UE may be configured to use different beams to transmit a specific number of multi-PRACH transmissions (e.g., N multi-PRACH transmissions). Furthermore, all embodiments are applicable to both the two-step RACH procedure and the four-step RACH procedure.

[0072] In one implementation, in all embodiments (e.g., shown in Table 700 of FIG. 7), for an RO UE group including N ROs, the RO UE group may be associated with one or more SSB indices. For example, based on a scenario in which SSB#0 is mapped to a set of ROs {RO#0, RO#1, RO#2, RO#3} and SSB#1 is mapped to another set of ROs {RO#4, RO#5, RO#6, RO#7}, the UE may be configured to determine RO UE group#0 including RO#0 and RO#1 or RO UE group#1 including RO#0 and RO#4 for two PRACH transmissions. Thus, RO UE group#0 is associated with SSB#0, and RO UE group#1 is associated with SSB#0 and SSB#1.

[0073] 19 shows a flowchart 1900 for a UE in accordance with various embodiments of the present disclosure. In step 1902, the UE determines M RO cell groups. In step 1904, the UE determines at least one RO UE group from the M RO cell groups, including N ROs corresponding to N multiple PRACH transmissions, based on any of Options 1 to 3 described in the present disclosure. In step 1906, the UE transmits one preamble in each of the N ROs of the at least one RO UE group in one PRACH attempt, e.g., using the same beam or different beams.

[0074] 20 shows a flow diagram 2000 illustrating a method of communication according to various embodiments. At step 2002, at least one first RO group including a plurality of Random Access Channel (RACH) Opportunities (ROs) corresponding to a plurality of PRACH transmissions in a multi-PRACH transmission from a communication device may be determined. At step 2004, a preamble may be transmitted in each of a plurality of ROs of the at least one first RO group.

[0075] In one implementation, a signal including information of at least one first random access channel (RACH) opportunity (RO) group may be generated, the at least one first RO group including a plurality of ROs corresponding to a plurality of multi-PRACH transmissions in a multi-physical RACH (PRACH) transmission from a communication device, the signal may be transmitted to the communication device, at least one multi-PRACH transmission may be received from the communication device, the at least one multi-PRACH transmission corresponds to the at least one first RO group, and a preamble may be detected in each of the at least one multi-PRACH transmission.

[0076] Figure 21 illustrates a schematic partial cross-sectional view of a communications device 2100 that may be implemented in accordance with various embodiments and examples shown in Figures 1-20. The communications device 2100 may be implemented as a UE or a base station in accordance with various embodiments.

[0077] The various functions and operations of the communications device 2100 are arranged in layers according to a hierarchical model, in which lower layers report to and receive instructions from higher layers according to 3GPP technical specifications, and for the sake of brevity, the details of the hierarchical model will not be described in this disclosure.

[0078] As shown in FIG. 21 , the communications device 2100 may include a circuit 2114, at least one wireless transmit (Tx) chain 2102 (also referred to herein as a transmitter 2102), at least one wireless receive (Rx) chain 2104 (also referred to herein as a receiver 2104), and at least one antenna 2112 (for simplicity, only one antenna is depicted in FIG. 21 for illustrative purposes). The circuit 2114 may include at least one controller 2106. The controller 2106 is used to perform tasks that the at least one controller 2106 is designed to perform with the assistance of software and hardware, including controlling communications with one or more other communications devices in a wireless network. The circuit 2114 may further include at least one transmit signal generator 2108 and at least one receive signal processor 2110. The at least one control unit 2106 may control at least one transmit signal generating unit 2108 for generating signals (e.g., signals indicating geographical areas) to be transmitted to one or more other communication devices via the at least one wireless transmitting unit 2102, and at least one receive signal processing unit 2110 for processing signals (e.g., signals indicating geographical areas) received from one or more other communication devices via the at least one wireless receiving unit 2104 under the control of the at least one control unit 2106. The at least one transmit signal generating unit 2108 and the at least one receive signal processing unit 2110 may be standalone modules of the communication device 2100 that communicate with the at least one control unit 2106 for the above-mentioned functions, as shown in FIG. 21 . Alternatively, the at least one transmit signal generating unit 2108 and the at least one receive signal processing unit 2110 may be included in the at least one control unit 2106. It will be apparent to those skilled in the art that the arrangement of these functional modules is flexible and may change according to actual needs and / or requirements. Data processing, virtual memory, and other related controls may be provided on appropriate circuit boards and / or within chipsets.In various embodiments, in operation, the at least one radio transmitter 2102, the at least one radio receiver 2104, and the at least one antenna 2112 may be controlled by the at least one controller 2106. It will be appreciated that the communications device 2100 may include multiple antennas 2212, for example, as shown in communications device 2200 of FIG. 22. Each of the multiple antennas 2212 may be connected to a corresponding Tx chain 2202 and Rx chain 2204 through a switcher or switch point. Alternatively, each of the multiple antennas 2212 may be connected to a corresponding Tx chain or Rx chain.

[0079] The communications device 2100, in operation, provides functionality necessary for RO group resources for multi-PRACH transmissions. For example, the communications device 2100 may be a UE, and the circuit 2114, in operation, may determine at least one first RO group including multiple random access channel (RACH) opportunities (ROs) corresponding to multiple PRACH transmissions in a multi-physical random access channel (multi-PRACH) transmission from the communications device. The transmitter 2102, in operation, may transmit a preamble in each of the multiple ROs of the at least one first RO group.

[0080] The ROs included in the first RO group may be the same as or different from the ROs included in other RO groups used by other communication devices. The circuit 2114 may be configured to determine the at least one first RO group based on explicit signaling from a system information block (SIB), a master information block (MIB), or higher layer parameters, or table-based signaling. The circuit 2114 may be configured to determine one or more second RO groups based on explicit signaling from a system information block (SIB), a master information block (MIB), or higher layer parameters, or table-based signaling, where each of the one or more second RO groups includes one or more ROs used among one or more communication devices, and the one or more second RO groups are commonly determined within a serving cell. The circuit 2114 may be configured to determine the at least one first RO group based on random selection from the one or more second RO groups. The circuit 2114 may be configured to determine at least one first RO group based on implicit signaling from one or more second RO groups through a circular shift or sequence order rule. The circuit 2114 may be configured to determine the at least one first RO group based on implicit signaling, the implicit signaling being an association of the at least one first RO group with a logical index of time or frequency resources from one or more second RO groups in a resource pool, the resource pool consisting of consecutive physical resource blocks (PRBs) and consecutive or non-consecutive logical slots for the multiple multi-PRACH transmissions. The circuit 2114 may be configured to determine the at least one first RO group based on implicit signaling, the implicit signaling being an association of the at least one first RO group with an identical logical index of preambles from one or more second RO groups in the resource pool, the resource pool consisting of consecutive PRBs and consecutive or non-consecutive logical slots for the multiple multi-PRACH transmissions.The circuit 2114 may be further configured to: determine at least one first RO group from the one or more second RO groups, each of the one or more second RO groups being dedicated to a particular number of multi-PRACH transmissions;

[0081] The circuit 2114 may be further configured to determine one or more second RO groups commonly determined within the serving cell based on clustering one or more ROs located proximate to each other in the time domain or the frequency domain, or both the time domain and the frequency domain, and the plurality of ROs of the first RO group are determined from the one or more second RO groups. The circuit 2114 also determines one or more RA-RNTI candidates based on association of at least one RO among the plurality of ROs of the first RO group with the one or more second RO groups.

[0082] The circuit 2114 may be further configured to cluster one or more frequency division multiplexed ROs (FDMed ROs) at one time instance and determine at least one first RO group based on the clustered one or more ROs. The circuit 2114 may be further configured to cluster one or more ROs located in the same time unit and determine at least one first RO group based on the clustered one or more ROs. The time unit may be a slot, a subframe, a frame, or the same period of a configuration for a specific number of PRACH transmissions. The circuit 2114 may be further configured to cluster one or more ROs located in the same frequency resource allocation and determine at least one first RO group based on the clustered one or more ROs. The clustered one or more ROs may form a second RO group of one or more second RO groups such that the clustered one or more ROs are used among one or more communication devices, and the one or more second RO groups are commonly determined within a serving cell.

[0083] Each of the at least one first RO group may be associated with two or more synchronization signal block (SSB) indices. Each of the at least one first RO group may be associated with one or more channel state information reference signal (CSI-RS) indices. The multiple ROs may include a separate RO separated from the single PRACH transmission or a shared RO shared with the single PRACH transmission. The circuit 2114 may be further configured to determine an RO communication device preamble group based on one or more preambles dedicated to the communication device, and to determine the at least one first RO group from the RO communication device preamble group. The transmitter 2102 may be further configured to transmit a preamble in each of the multiple ROs of the at least one first RO group using the same beam. The transmitter 2102 may be further configured to transmit a preamble in each of the multiple ROs of the at least one first RO group using different beams. The transmitter 2102 may be further configured to transmit a preamble in each of the multiple ROs of the at least one first RO group using frequency hopping. The circuit 2114 may be configured to include the same RO in two or more first RO groups.

[0084] The circuit 2114 may be further configured to determine a first RO group for each of a plurality of transmit (Tx) chains of the communication device from the at least one first RO group, and the transmitter unit is further configured to transmit a preamble in each of the first RO groups for each of the plurality of transmit (Tx) chains.

[0085] The communications device 2100 may be a base station, and the circuit 2114, upon operation, may generate a signal including information of at least one first random access channel (RACH) opportunity (RO) group. The at least one first RO group includes a plurality of ROs corresponding to a plurality of multi-physical RACH (PRACH) transmissions in a multi-PRACH transmission from the communications device. The transmitter 2102, upon operation, may transmit a signal to the communications device. The receiver 2104, upon operation, may receive at least one multi-PRACH transmission from the communications device, the at least one multi-PRACH transmission corresponding to the at least one first RO group. The circuit 2114 may detect a preamble in each of the at least one multi-PRACH transmission.

[0086] The circuit 2114 may be further configured to generate a signal including information of at least one first RO group and one or more second RO groups, where the one or more second RO groups are commonly determined in the serving cell. The transmitter 2102 may be configured to transmit the signal to the communication device.

[0087] (control signal) In the present disclosure, the downlink control signal (information) according to the present disclosure may be a signal (information) transmitted via a PDCCH of a physical layer, or may be a signal (information) transmitted via a MAC Control Element (CE) of a higher layer or an RRC. The downlink control signal may be a predefined signal (information).

[0088] The uplink control signal (information) according to the present disclosure may be a signal (information) transmitted via a PUCCH of a physical layer, or may be a signal (information) transmitted via a MAC CE of a higher layer or RRC. The uplink control signal may also be a predefined signal (information). The uplink control signal may be uplink control information (UCI), first-stage sidelink control information (SCI), or second-stage SCI.

[0089] (base station) In the present disclosure, a base station may be, for example, a Transmission Reception Point (TRP), a cluster head, an access point, a Remote Radio Head (RRH), an eNodeB (eNB), a gNodeB (gNB), a Base Station (BS), a Base Transceiver Station (BTS), a base unit, or a gateway. Furthermore, in sidelink communication, a terminal may be used instead of a base station. The base station may be a relay device that relays communication between an upper node and a terminal. The base station may be a roadside unit.

[0090] (Uplink / Downlink / Sidelink) The present disclosure may be applied to any of the uplink, downlink, and sidelink.

[0091] For example, the present disclosure may be applied to uplink channels such as PUSCH, PUCCH, and PRACH, downlink channels such as PDSCH, PDCCH, and PBCH, and sidelinks such as PSSCH (Physical Sidelink Shared Channel), PSCCH (Physical Sidelink Control Channel), and PSBCH (Physical Sidelink Broadcast Channel).

[0092] The PDCCH, PDSCH, PUSCH, and PUCCH are examples of a downlink control channel, a downlink data channel, an uplink data channel, and an uplink control channel, respectively. The PSCCH and PSSCH are examples of a sidelink control channel and a sidelink data channel, respectively. The PBCH and PSBCH are examples of a broadcast channel, and the PRACH is an example of a random access channel.

[0093] (Data channel / Control channel) The present disclosure may be applied to both data channels and control channels. The channels in this disclosure may be replaced with data channels including PDSCH, PUSCH, and PSSCH, and / or control channels including PDCCH, PUCCH, PBCH, PSCCH, and PSBCH.

[0094] (reference signal) In this disclosure, a reference signal is a signal known to both a base station and a mobile station, and each reference signal may be referred to as a reference signal (RS) or a pilot signal. A reference signal may be any of a demodulation reference signal (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).

[0095] (time interval) In the present disclosure, the time resource unit is not limited to one or a combination of a slot and a symbol, and may be a time resource unit such as a frame, a superframe, a subframe, a slot, a subslot of a time slot, a minislot, or a symbol, an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier-Frequency Division Multiplexing Access (SC-FDMA) symbol, or other time resource unit. The number of symbols included in one slot is not limited to the number of symbols exemplified in the above-mentioned embodiments, and may be other numbers of symbols.

[0096] (frequency band) The present disclosure may be applied to both licensed and unlicensed bands.

[0097] (communication) The present disclosure may be applied to communication between a base station and a terminal (Uu link communication), communication between terminals (sidelink communication), and vehicle-to-everything (V2X) communication. The channels in the present disclosure may be replaced with PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, and PBCH.

[0098] The present disclosure may also be applied to a terrestrial network or a non-terrestrial network (NTN: Non-Terrestrial Network) that uses a satellite or a High Altitude Pseudo Satellite (HAPS). The present disclosure may also be applied to a network with a large cell size or a terrestrial network in which the delay is large compared to the symbol length or slot length, such as an ultra-wideband transmission network.

[0099] (antenna port) An antenna port refers to a logical antenna (antenna group) formed by one or more physical antennas (multiple antennas are possible). That is, an antenna port does not necessarily refer to one physical antenna, but may refer to an array antenna formed by multiple antennas. For example, the number of physical antennas forming an antenna port is not defined. Instead, an antenna port is defined as the smallest unit by which a terminal can transmit a reference signal. An antenna port may also be defined as the smallest unit for multiplying a weight of a precoding vector.

[0100] As described above, embodiments of the present disclosure provide an improved communication system, communication method, and communication device that advantageously determine RO group resources for multi-PRACH transmissions.

[0101] The present disclosure can be implemented by software, hardware, or software cooperating with hardware. Each functional block described in the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit. Each process described in the above embodiments may be partially or entirely controlled by a single LSI or a combination of LSIs. The LSI may be formed as an individual chip, or a single chip may be formed to include some or all of the functional blocks. The LSI may include a data input / output unit coupled to it. Depending on the degree of integration, the LSI may be referred to as an IC, system LSI, super LSI, or ultra LSI. However, the technology for implementing an integrated circuit is not limited to LSI, and may be implemented using dedicated circuits, general-purpose processors, or dedicated processors. Furthermore, FPGAs (field programmable gate arrays), which can be programmed after LSI fabrication, and reconfigurable processors, which can reconfigure the connections and settings of circuit cells located within the LSI, may also be used. The present disclosure can be implemented using digital or analog processing. If, as a result of advances in semiconductor technology or other derivative technologies, LSI is replaced by future integrated circuit technologies, these future integrated circuit technologies can be used to integrate functional blocks. Biotechnology can also be applied.

[0102] The present disclosure may be implemented by any type of apparatus, device, or system having communication capabilities (collectively referred to as communication apparatus).

[0103] Non-limiting examples of such communication devices include telephones (e.g., mobile phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, netbooks), cameras (e.g., digital still cameras / video cameras), digital players (e.g., digital audio players / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices), game consoles, digital book readers, telehealth / telemedicine (remote healthcare / medicine prescription) devices, and vehicles (e.g., cars, airplanes, ships) that provide communication capabilities, in various combinations.

[0104] Communications equipment is not limited to portable or mobile equipment, but also includes non-portable or fixed equipment, devices, and systems of any kind, such as smart home devices (appliances, lighting equipment, smart meters or metering devices, control panels, etc.), vending machines, and any other "things" that may exist on an Internet of Things (IoT) network.

[0105] Communications include data communications via cellular systems, wireless LAN systems, communications satellite systems, etc., as well as data communications via combinations of these.

[0106] A communications device may include devices such as controllers and sensors coupled to the communications device to perform the communications functions described in this disclosure, including, for example, controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications device.

[0107] The communications apparatus may further include infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the apparatus in the above non-limiting examples.

[0108] Although some features of the various embodiments are described with reference to the apparatus, it will be understood that the corresponding features also apply to the methods of the various embodiments, and vice versa.

[0109] The present disclosure may refer to the following statements:

[0110] Statement 1. A communication device, a circuit for determining, during operation, at least one first Random Access Channel (RACH) group including a plurality of Random Access Channel (RACH) opportunities (RACH Occasions) corresponding to a plurality of multi-Physical Random Access Channel (multi-PRACH) transmissions in a multi-PRACH transmission from a communication device; a transmitter that, in operation, transmits a preamble on each of a plurality of ROs of at least one first RO group; A communication device comprising:

[0111] Statement 2. The ROs included in the first RO group are the same as or different from the ROs included in other RO groups used by other communication devices; 10. The communication device of claim 1.

[0112] Statement 3. The circuitry is configured to determine the at least one first RO group based on explicit notification from a System Information Block (SIB), a Master Information Block (MIB), or higher layer parameters, or based on table-based notification. 3. A communication device according to claim 1 or 2.

[0113] Statement 4. The circuitry is configured to determine one or more second RO groups based on explicit notification from a system information block (SIB), a master information block (MIB), or higher layer parameters, or table-based notification, each of the one or more second RO groups including one or more ROs used between one or more communication devices, and the one or more second RO groups being commonly determined in a serving cell; 3. A communication device according to claim 1 or 2.

[0114] Statement 5. the circuitry is configured to determine the at least one first RO group based on a random selection from the one or more second RO groups; 10. The communication device of claim 4.

[0115] Statement 6. The circuitry is configured to determine at least one first RO group based on implicit notification through a circular shift or sequence order rule from one or more second RO groups. 10. The communication device of claim 4.

[0116] Statement 7. The circuitry is configured to determine at least one first RO group based on an implicit signaling, the implicit signaling being an association of the at least one first RO group with a logical index of time or frequency resources from one or more second RO groups in a resource pool, the resource pool consisting of contiguous physical resource blocks (PRBs) and contiguous or non-contiguous logical slots for multiple multi-PRACH transmissions. 10. The communication device of claim 4.

[0117] Statement 8. The circuitry is configured to determine at least one first RO group based on an implicit notification, the implicit notification being an association of the at least one first RO group with identical logical indices of preambles from one or more second RO groups in a resource pool, the resource pool consisting of consecutive PRBs and consecutive or non-consecutive logical slots for multiple multi-PRACH transmissions. 10. The communication device of claim 4.

[0118] Statement 9. The circuit is further configured to: determine one or more second RO groups commonly determined in the serving cell based on clustering one or more ROs located proximate to each other in a time domain or a frequency domain, or both the time domain and the frequency domain, wherein the first RO group is determined from the one or more second RO groups; and determine one or more RA-RNTI candidates based on an association of at least one RO among the plurality of ROs in the first RO group with the one or more second RO groups. 3. A communication device according to claim 1 or 2.

[0119] Statement 10. The circuitry is further configured to cluster one or more frequency division multiplexed ROs (FDMed ROs) at a time instance and determine at least one first RO group based on the clustered one or more ROs. 3. A communication device according to claim 1 or 2.

[0120] Statement 11. The circuitry is further configured to cluster one or more ROs located in the same time unit, and determine at least one first group of ROs based on the clustered one or more ROs. 3. A communication device according to claim 1 or 2.

[0121] Statement 12. The time unit is a slot, a subframe, a frame, or an identical period of configuration for a certain number of multiple PRACH transmissions. 12. The communication device of claim 11.

[0122] Statement 13. The circuitry is further configured to cluster one or more ROs located in the same frequency resource allocation, and determine at least one first RO group based on the clustered one or more ROs. 3. A communication device according to claim 1 or 2.

[0123] Statement 14. The clustered one or more ROs form a second RO group among one or more second RO groups such that the clustered one or more ROs are used among one or more communication devices, and the one or more second RO groups are commonly determined in a serving cell; A communication device according to any one of statements 10 to 13.

[0124] Statement 15. the circuitry is further configured to replicate one or more sets of the one or more second RO groups when the number of ROs in the at least one first RO group exceeds a total number of ROs in the one or more second RO groups; 10. The communication device of claim 4.

[0125] Statement 16. The circuitry is further configured to determine at least one first RO group from the one or more second RO groups, each of the one or more second RO groups being dedicated to a particular number of multi-PRACH transmissions. 10. The communication device of claim 4.

[0126] Statement 17. each of the at least one first RO group is associated with two or more Synchronization Signal Block (SSB) indices; 3. A communication device according to claim 1 or 2.

[0127] Statement 18. each of the at least one first RO group is associated with one or more channel state information reference signal (CSI-RS) indices; 3. A communication device according to claim 1 or 2.

[0128] Statement 19. The multiple ROs include separate ROs separated from a single PRACH transmission or shared ROs shared with a single PRACH transmission. 3. A communication device according to claim 1 or 2.

[0129] statement 20 The circuitry is further configured to determine an RO communication device preamble group based on one or more preambles dedicated to the communication device, and to determine at least one first RO group from the RO communication device preamble group. 3. A communication device according to claim 1 or 2.

[0130] Statement 21. the transmitter is further configured to transmit the preamble in each of the plurality of ROs in the at least one first RO group using the same beam. 3. A communication device according to claim 1 or 2.

[0131] Statement 22. the transmitter is further configured to transmit the preamble in each of the plurality of ROs of the at least one first RO group using different beams. 3. A communication device according to claim 1 or 2.

[0132] Statement 23. the transmitter is further configured to transmit the preamble in each of the plurality of ROs of the at least one first RO group using frequency hopping. 3. A communication device according to claim 1 or 2.

[0133] Statement 24. The circuitry is further configured to determine a first RO group for each of a plurality of transmit (Tx) chains of the communication device from the at least one first RO group, and the transmitter is further configured to transmit a preamble in each of the first RO groups for each of the plurality of transmit (Tx) chains. A communication device according to any one of statements 1 to 23.

[0134] Statement 25. the circuitry is configured to include the same RO in two or more first RO groups; 3. A communication device according to claim 1 or 2.

[0135] Statement 26. a circuit for generating, in operation, a signal including information of at least one first random access channel (RACH) opportunity (RO) group including a plurality of RACH opportunities corresponding to a plurality of multi-physical RACH (PRACH) transmissions in a multi-PRACH transmission from a communication device; a transmitter that, in operation, transmits a signal to a communication device; a receiver configured, in operation, to receive at least one multi-PRACH transmission corresponding to at least one first RO group from a communication device; the circuit detects a preamble in each of the at least one multi-PRACH transmission. Base station.

[0136] Statement 27. the circuitry is further configured to generate a signal including information of at least one first RO group and one or more second RO groups, the one or more second RO groups being commonly determined in a serving cell; and the transmitter is configured to transmit the signal to the communication device. 27. The base station of claim 26.

[0137] Statement 28. determining at least one first random access channel (RACH) opportunity (RO) group including a plurality of RACH ROs corresponding to a plurality of PRACH transmissions in a multi-PRACH transmission from the communication device; transmitting a preamble in each of a plurality of ROs in at least one first RO group; A communication method, including:

[0138] Statement 29. generating a signal including information of at least one first random access channel (RACH) opportunity (RO) group, the at least one first RO group including a plurality of ROs corresponding to a plurality of multi-physical RACH (PRACH) transmissions in a multi-PRACH transmission from a communication device; transmitting a signal to a communication device; receiving at least one multi-PRACH transmission corresponding to at least one first RO group from a communication device; detecting a preamble in each of the at least one multi-PRACH transmission; A communication method, including:

[0139] Those skilled in the art will appreciate that numerous variations and / or modifications may be made to the present disclosure as set forth in the specific embodiments without departing from the spirit or scope of the disclosure as broadly described, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

1. A communication device, a circuit for determining, during operation, at least one first Random Access Channel (RACH) opportunity (RO) group including a plurality of Random Access Channel (RACH) opportunities (ROs) corresponding to a plurality of multi-Physical Random Access Channel (multi-PRACH) transmissions in a multi-PRACH transmission from the communication device; a transmitter configured, in operation, to transmit a preamble in each of the plurality of ROs of the at least one first RO group; A communication device comprising:

2. The plurality of ROs included in the first RO group are the same as or different from the plurality of ROs included in other RO groups used by other communication devices; The communication device according to claim 1 .

3. the circuitry is configured to determine the at least one first RO group based on explicit signaling from a System Information Block (SIB), a Master Information Block (MIB), or higher layer parameters, or table-based signaling.

3. The communication device according to claim 1 or 2.

4. the circuitry is configured to determine one or more second RO groups based on explicit notification from a system information block (SIB), a master information block (MIB), or higher layer parameters, or table-based notification, each of the one or more second RO groups including one or more ROs used between one or more communication devices, and the one or more second RO groups being commonly determined in a serving cell; 3. The communication device according to claim 1 or 2.

5. the circuitry is configured to determine the at least one first RO group based on a random selection from the one or more second RO groups. The communication device according to claim 4.

6. the circuitry is configured to determine the at least one first RO group based on implicit notification from the one or more second RO groups through a circular shift or sequence order rule; The communication device according to claim 4.

7. the circuitry is configured to determine the at least one first RO group based on an implicit signaling, the implicit signaling being an association of the at least one first RO group with a logical index of time or frequency resources from the one or more second RO groups in a resource pool, the resource pool consisting of contiguous Physical Resource Blocks (PRBs) and contiguous or non-contiguous logical slots for multiple multi-PRACH transmissions. The communication device according to claim 4.

8. The circuitry is configured to determine the at least one first RO group based on an implicit signaling, the implicit signaling being an association of the at least one first RO group with the same logical index of preambles from the one or more second RO groups in a resource pool, the resource pool consisting of consecutive PRBs and consecutive or non-consecutive logical slots for multiple multi-PRACH transmissions. The communication device according to claim 4.

9. The circuitry is further configured to: determine one or more second RO groups commonly determined in a serving cell based on clustering one or more ROs located proximate to each other in a time domain or a frequency domain, or both a time domain and a frequency domain, the first RO group being determined from the one or more second RO groups; and determine one or more RA-RNTI candidates based on association of at least one RO among the plurality of ROs of the first RO group with the one or more second RO groups.

3. The communication device according to claim 1 or 2.

10. the circuitry is further configured to cluster one or more Frequency Division Multiplexed ROs (FDMed ROs) at a time instance and determine the at least one first RO group based on the clustered one or more ROs.

3. The communication device according to claim 1 or 2.

11. the circuitry is further configured to cluster one or more ROs located in the same time unit, and determine the at least one first RO group based on the clustered one or more ROs.

3. The communication device according to claim 1 or 2.

12. The time unit is a slot, a subframe, a frame, or a set period for a specific number of PRACH transmissions. The communication device according to claim 11.

13. the circuitry is further configured to cluster one or more ROs located in the same frequency resource allocation, and determine the at least one first RO group based on the clustered one or more ROs.

3. The communication device according to claim 1 or 2.

14. the one or more clustered ROs form a second RO group among one or more second RO groups such that the one or more clustered ROs are used among one or more communication devices, and the one or more second RO groups are commonly determined in a serving cell; The communication device according to claim 10.

15. the circuitry is further configured to replicate one or more sets of the one or more second RO groups when the number of ROs of the at least one first RO group exceeds a total number of ROs of the one or more second RO groups. The communication device according to claim 4.

16. the circuitry is further configured to determine the at least one first RO group from the one or more second RO groups, each of the one or more second RO groups being dedicated to a specific number of multi-PRACH transmissions. The communication device according to claim 4.

17. each of the at least one first RO group is associated with two or more Synchronization Signal Block (SSB) indices; 3. The communication device according to claim 1 or 2.

18. a circuit for generating, during operation, a signal including information of at least one first random access channel (RACH) opportunity (RO) group including a plurality of RACH ROs corresponding to a plurality of multi-physical RACH (PRACH) transmissions in a multi-PRACH transmission from a communication device; a transmitter that, in operation, transmits the signal to the communication device; a receiver that, during operation, receives at least one multi-PRACH transmission corresponding to the at least one first RO group from the communication device; the circuitry detects a preamble in each of the at least one multi-PRACH transmission. Base station.

19. the circuitry is further configured to generate a signal including information of at least one first RO group and one or more second RO groups, the one or more second RO groups being commonly determined in a serving cell; and the transmitter is configured to transmit the signal to the communication device.

20. The base station of claim 18.

20. determining at least one first random access channel (RACH) opportunity (RO) group including a plurality of RACH ROs corresponding to a plurality of PRACH transmissions in the multi-PRACH transmission from the communication device; transmitting a preamble in each of the plurality of ROs of the at least one first RO group; A communication method, including:

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