COMMUNICATION APPARATUS, COMMUNICATION METHOD AND INTEGRATED CIRCUIT FOR MULTIPLE PRACH TRANSMISSION - Patent application

Abstract

The present disclosure provides a communication device and a communication method for multi-PRACH transmission, the communication device comprising: a receiver, which, in operation, receives control information related to the multi-PRACH transmission; and a transmitter, which, in operation, transmits the multi-PRACH transmission including the multiple PRACH transmissions based on the control information.

Description

[Technical field]

[0001] The following disclosure relates to a communication apparatus and method for multi-physical random access channel (multi-PRACH) transmission, and more particularly, to a communication apparatus and method for multi-PRACH transmission across multiple RACH occasions (ROs) in New Radio (NR). [Background technology]

[0002] In the current Random Access Channel (RACH) procedure, a User Equipment (UE) receives System Information Block 1 (SIB1) to derive Physical Random Access Channel (PRACH) resources, which indicate RACH Occasions (ROs) in time and frequency domain resources, as well as Synchronization Signal / PBCH Block (SSB)-to-RO mapping, which is the number of SSBs per RO and the number of preambles R per RO. The UE then selects one RO in the initial Uplink Bandwidth Part (UL BWP) and transmits a PRACH preamble (so-called Msg1 or PRACH transmission), which is called a single PRACH transmission. Referring to the exemplary four-step random access procedure between a UE and a base station or gNodeB (gNB) in the diagram 600 of FIG. 6, a random access preamble (e.g., a PRACH preamble) is transmitted from the UE to the gNB in ​​step 602. In step 604, the UE receives a Random Access Response (RAR) from the gNB. In step 606, the scheduled transmission is transmitted from the UE to the gNB. In step 608, the UE receives a contention resolution for the transmission from the gNB. The UE cannot select another PRACH preamble until the expiration of the RAR window for the same transmitted PRACH preamble.

[0003] In case of failure in transmission or reception of the PRACH preamble, the PRACH preamble may be repeatedly transmitted with increased transmission power by a configurable offset between each transmission (i.e., power ramping) until the UE receives an Msg2 (e.g., RAR) from the base station or gNB, or a configurable maximum number of retransmissions is performed, or the UE-side transmission power reaches a configurable maximum power. In the latter two cases, the random access attempt is declared as failed.

[0004] In practical operation, it is expected that the performance of UL channels will be challenging in most scenarios. Also, there are vertical use cases that require a large amount of UL traffic, e.g. video uploading or camera surveillance. In terms of coverage performance, studies have identified PRACH as one of the bottleneck channels. However, due to the limited scope of coverage extension (CovEnh) in Rel.17, PRACH coverage has not been extended. A new work item (WI) for further New Radio (NR) CovEnh has been approved in Rel.18. One of its main objectives is to: - realizing multiple PRACH transmissions using the same beam in a four-step RACH procedure; and - to study and, if justified, specify PRACH transmission using different beams in a four-step RACH procedure; This is the specification of PRACH coverage extension (RAN1, RAN2) [RP-213579]. The PRACH extension targets Frequency Range 2 (FR2) and may be applied to FR1 if applicable to FR1. Furthermore, the PRACH extension targets short PRACH formats and may be applied to other formats if applicable to other formats.

[0005] However, there has been little discussion so far about communication devices and methods for multi-PRACH transmission.

[0006] Therefore, there is a need for a communication apparatus and method that provides a feasible technical solution for multi-PRACH transmission across multiple ROs in NR. 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 technique of this disclosure. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] 3GPP(registered trademark) TS 38.211 [Non-Patent Document 2] 3GPP TS 38.300 v16.3.0 [Non-Patent Document 3] 3GPP TS 23.502 [Non-Patent Document 4] ITU-R M.2083 [Non-Patent Document 5] 3GPP TR 38.913 [Non-Patent Document 6] 3GPP TS 23.287 v16.4.0 [Non-Patent Document 7] 3GPP TS 38.141-01 Summary of the Invention [Problem to be solved by the invention]

[0008] The non-limiting exemplary embodiments facilitate providing a communications apparatus and method for multi-PRACH transmission. [Means for solving the problem]

[0009] According to a first embodiment of the present disclosure, a communication device is provided that includes a receiving unit that, during operation, receives control information related to a multi-PRACH transmission, and a transmitting unit that, during operation, transmits a multi-PRACH transmission including a plurality of PRACH transmissions based on the control information.

[0010] According to a second embodiment of the present disclosure, there is provided a base station comprising: a circuit for generating control information related to a multi-PRACH transmission during operation; a transmitting unit for transmitting the control information to a communication device during operation; and a receiving unit for receiving the multi-PRACH transmission from the communication device during operation.

[0011] According to a third embodiment of the present disclosure, there is provided a communication method including: receiving control information related to a multi-PRACH transmission; and transmitting a multi-PRACH transmission including a plurality of PRACH transmissions based on the control information.

[0012] 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.

[0013] Further benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings, and these benefits and / or advantages may be obtained individually by various embodiments and features of the specification and drawings, and it is not necessary for all of the embodiments and features to be present in order to obtain one or more of such benefits and / or advantages.

[0014] 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 description of the drawings]

[0015] [Figure 1] FIG. 1 illustrates an exemplary 3GPP NR-RAN architecture. [Diagram 2] Schematic diagram showing the functional division between NG-RAN and 5GC [Diagram 3] Sequence diagram of radio resource control (RRC) connection setup / reconfiguration procedure [Figure 4]Schematic diagram showing usage scenarios for enhanced Mobile BroadBand (eMBB), massive Machine Type Communications (mMTC), and Ultra Reliable and Low Latency Communications (URLLC) [Diagram 5] Block diagram illustrating an example 5G system architecture for V2X communications in a non-roaming scenario [Figure 6] Diagram showing an example of a four-step random access procedure [Figure 7] FIG. 1 illustrates an example of PRACH preamble detection from multiple PRACH transmissions in the time domain. [Figure 8A] FIG. 2 is a schematic diagram of a multi-PRACH transmission for different Coverage Enhancement (CE) levels according to an embodiment E1; [Figure 8B] FIG. 1 is a schematic diagram of a multi-PRACH transmission for different Coverage Extension (CE) levels according to an embodiment E2; [Figure 9] FIG. 2 is a schematic diagram of multi-PRACH transmission for different CE levels according to a variant of embodiment E1; [Figure 10] FIG. 13 is a schematic diagram of multi-PRACH transmission for different CE levels according to another variant of embodiment E1; [Figure 11A] FIG. 13 shows an example of higher layer parameters indicating RO for multiple PRACH transmission according to embodiment E2. [Figure 11B] FIG. 1 shows Table 6.3.3.2-3 (random access configuration for FR1 and unpaired spectrum) of NREL 1 extended to show RO for multi-PRACH transmission according to embodiment E2. [Figure 12] FIG. 1 illustrates how a PRACH preamble can be split, according to various embodiments. [Figure 13] FIG. 1 illustrates how frequency division can be utilized, according to various embodiments. [Figure 14]FIG. 1 illustrates an initial uplink bandwidth portion (UL BWP) for a reduced capability (RedCap) UE and an initial UL BWP for a non-RedCap UE according to an embodiment. [Figure 15] FIG. 1 shows a cross-division duplex (XDD) operation according to an embodiment. [Figure 16] FIG. 13 illustrates frequency resource allocation per RO in XDD operation according to embodiment E3. [Figure 17] FIG. 1 illustrates frequency resource allocation per RO for RedCap UE according to embodiment E3. [Figure 18] FIG. 1 shows SSB-to-RO mapping for RedCap UE or XDD operation according to a variation of embodiment E3. [Figure 19A] FIG. 13 is an expanded view of a time domain RO for a RedCap UE according to a variation of embodiment E3; [Figure 19B] FIG. 13 is an expanded view of a time domain RO for a RedCap UE according to a variation of embodiment E3; [Figure 20A] FIG. 1 is a flow chart illustrating an example for a UE operation with multiple PRACH transmission patterns configured according to embodiment E1. [Figure 20B] Flowchart of UE operation according to embodiment E2 [Figure 20C] Flowchart of RedCap UE operation according to embodiment E3 [Figure 21] 1 is a flow diagram illustrating a communication method according to various embodiments. [Figure 22] FIG. 1 is a schematic diagram of an example communication device according to various embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] 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 flow charts may be exaggerated relative to other elements to help improve understanding of the embodiments.

[0017] Some embodiments of the present disclosure are now described, by way of example, with reference to the drawings in which like reference numbers and letters indicate similar or equivalent elements.

[0018] In particular, the system architecture assumes an NG-RAN (Next Generation - Radio Access Network) comprising gNBs as a whole. The gNBs provide UE-side termination of NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocols. The gNBs are connected to each other via an Xn interface. The gNBs are also connected to a Next Generation Core (NGC) via a Next Generation (NG) interface, more specifically to an Access and Mobility Management Function (AMF) (e.g., a specific core entity performing AMF) via an NG-C interface, and to a User Plane Function (UPF) (e.g., a specific core entity performing UPF) via an NG-U interface. The NG-RAN architecture is shown in FIG. 1 (see, for example, Section 4 of Non-Patent Document 2).

[0019] The NR user plane protocol stack (see, for example, Section 4.4.1 of Non-Patent Document 2) includes a Packet Data Convergence Protocol (PDCP) sublayer (see, for example, Section 6.4 of Non-Patent Document 2), a Radio Link Control (RLC) sublayer (see, for example, Section 6.3 of Non-Patent Document 2), and a Medium Access Control (MAC) sublayer (see, for example, Section 6.2 of Non-Patent Document 2), which are terminated on the network side at the gNB. A new Access Stratum (AS) sublayer (Service Data Adaptation Protocol (SDAP)) is also introduced on top of the PDCP (see, for example, Section 6.5 of Non-Patent Document 2). A control plane protocol stack is also defined for NR (see, for example, Section 4.4.2 of Non-Patent Document 2). An overview of Layer 2 functions is given in Section 6 of Non-Patent Document 2. The functions of the PDCP sublayer, the RLC sublayer, and the MAC sublayer are listed in Sections 6.4, 6.3, and 6.2 of Non-Patent Document 2, respectively. The functions of the RRC layer are listed in section 7 of 3GPP TS 2013-01-13011. Additionally, sidelink communication is introduced in 3GPP TS 2013-01-13011. 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 2013-01-13011).

[0020] For example, the Medium-Access-Control layer handles logical channel multiplexing and scheduling and scheduling related functions, including handling various numerologies.

[0021] For example, the physical layer (PHY) is responsible for 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 the transmission of a particular transport channel, and each transport channel is mapped to a corresponding physical channel. For example, the physical channels are PRACH in the uplink, PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel) in the uplink, PDSCH (Physical Downlink Shared Channel) and PDCCH (Physical Downlink Control Channel) in the downlink, and PBCH (Physical Broadcast Channel). 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).

[0022] NR use cases / deployment scenarios may include enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine type communication (mMTC), which have diverse requirements in terms of data rate, latency, and coverage. For example, eMBB is expected to support peak data rates (20 Gbps in downlink and 10 Gbps in uplink) and effective (user-experienced) data rates that are about three times higher than those offered by IMT-Advanced. On the other hand, for URLLC, more stringent requirements are placed on ultra-low latency (0.5 ms for user plane latency in UL and DL respectively) and high reliability (1-10 Mbps within 1 ms). -5 Finally, mMTC is preferably regulated to have high connection density (1,000,000 devices / km in urban environments). 2 ), wide coverage in hostile environments, and extremely long battery life (15 years) for a low-cost device.

[0023] Therefore, OFDM numerology (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) suitable for one use case may not be valid for other use cases. For example, low latency services may preferably require a shorter symbol length (and therefore a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also called TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP length than scenarios with smaller delay spreads. Subcarrier spacing should be optimized accordingly to maintain a similar CP overhead. NR may support one or more subcarrier spacing values. Thus, currently subcarrier spacings of 15 kHz, 30 kHz, 60 kHz... are considered. Symbol length T u and the subcarrier spacing Δf is expressed by the formula Δf=1 / T u Similar to LTE systems, the term "resource element" can be used to mean the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0024] In the new wireless system 5G-NR, for each numerology and each carrier, a resource grid of subcarriers and OFDM symbols is defined for the uplink and downlink, respectively. Each element of the resource grid is called a resource element and is specified based on a frequency index in the frequency domain and a symbol position in the time domain (see Non-Patent Document 1 V16.3.0).

[0025] Figure 2 shows the functional separation between NG-RAN and 5GC. The logical node of NG-RAN is gNB or ng-eNB. 5GC has logical nodes AMF, UPF, and SMF.

[0026] In particular, the gNB and ng-eNB host the following main functions: - Radio Resource Management functions such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, dynamic allocation (scheduling) of resources to UEs in both uplink and downlink; - IP header compression, encryption, and integrity protection of data; - Selection of the AMF at UE attach time if routing to the AMF cannot be determined from information provided by the UE; - Routing of user plane data towards the UPF; - Routing of control plane information towards AMF; - Setting up and tearing down connections; - Scheduling and sending paging messages; - Scheduling and transmission of system broadcast information (sourced from AMF or Operation, Admission, Maintenance Function (OAM)); - Setting up measurements and reporting of measurements for mobility and scheduling; - Transport level packet marking in the uplink; - Session management; - Support for network slicing; - QoS flow management and mapping to data radio bearers; - Support for UEs in RRC_INACTIVE state; - Non-Access Stratum (NAS) message delivery function; - Sharing of radio access networks; - Dual connectivity; - Close cooperation between NR and E-UTRA.

[0027] The Access and Mobility Management Function (AMF) hosts the following main functions: - Termination of Non-Access Stratum (NAS) signalling; - NAS signaling security; - Access Stratum (AS) security control; - 3GPP Core Network (CN) inter-node signalling for mobility between access networks; - Reachability to idle mode UEs (including control and execution of paging retransmissions); - Managing the registration area; - Support for intra-system and inter-system mobility; - Access authentication; - Access authorization including roaming privilege checks; - Mobility management control (subscription and policies); - Support for network slicing; - Select the Session Management Function (SMF).

[0028] Additionally, the User Plane Function (UPF) hosts 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 part; - Traffic usage reporting; - an uplink classifier that supports routing of traffic flows to the data network; - Branching Point to support multi-homed PDU sessions; - QoS processing for the user plane (e.g., packet filtering, gating, UL / DL rate enforcement); - Validation of uplink traffic (mapping of SDF to QoS flows); - Downlink packet buffering and downlink data notification triggering.

[0029] Finally, the Session Management Function (SMF) hosts the following main functions: - Session management; - Allocation and management of IP addresses for UEs; - Selection and control of UPF; - Ability to configure traffic steering in the User Plane Function (UPF) to route traffic to the appropriate destination; - Controls policy enforcement and QoS; - Notification of downlink data.

[0030] Figure 3 shows some of the interactions between the UE, gNB and AMF (5GC entities) when the UE transitions from RRC_IDLE to RRC_CONNECTED in the NAS part (see Non-Patent Document 2). The transition steps are as follows: 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 may reject a request are described below.) 3. The first NAS message from the UE, piggybacked in RRCSetupComplete, is sent to the AMF. Additional NAS messages may be exchanged between the UE and the AMF, see 3GPP TS 23.122: "Non-Access Stratum (NAS) Functions Associated with a Mobile Station in Idle Mode" (reference

[22] ). 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. The 7 / 7a.gNB activates AS security with the UE. The 8 / 8a.gNB performs reconfiguration to set up SRB2 and DRB. 9. The gNB notifies the AMF that the setup procedure is complete.

[0031] RRC is a higher layer signaling (protocol) used for the configuration of the UE and the gNB. In particular, with this transition, the AMF prepares UE context data (which includes, for example, PDU session context, security keys, UE Radio Capability, UE Security Capabilities, etc.) and sends it to the gNB with an INITIAL CONTEXT SETUP REQUEST. The gNB then activates AS security together with the UE. This is done by the gNB sending a SecurityModeCommand message to the UE, and the UE responding with a SecurityModeComplete message to the gNB. The gNB then reconfigures to set up Signaling Radio Bearer 2 (SRB2) and Data Radio Bearer (DRB) by sending an RRCReconfiguration message to the UE and receiving an RRCReconfigurationComplete from the UE. For signaling-only connections, the steps related to RRCReconfiguration are omitted since SRB2 and DRB are not set up. Finally, the gNB informs the AMF that the setup procedure is complete with an INITIAL CONTEXT SETUP RESPONSE.

[0032] Figure 4 shows some of the use cases for 5G NR. The 3rd generation partnership project new radio (3GPP NR) considers three use cases that were envisioned by IMT-2020 to support a wide variety of services and applications. The first phase of specifications for enhanced mobile-broadband (eMBB) has been completed. Current and future work includes standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC), in addition to expanding support for eMBB. Figure 4 shows some examples of expected usage scenarios for IMT beyond 2020 (see, for example, Figure 2 in Non-Patent Document 4).

[0033] URLLC use cases have stringent requirements for performance such as throughput, latency, and availability, and are envisioned as one of the necessary to enable upcoming vertical applications such as wireless control of industrial production or manufacturing processes, remote medical surgery, automation of power transmission and distribution in smart grids, and road safety. URLLC's ultra-high reliability is supported by identifying technologies that meet the requirements set by NR URLLC in Release 15. Key requirements for NR URLLC in Release 15 include a target user plane latency of 0.5 ms in UL (uplink) and 0.5 ms in DL (downlink). A typical URLLC requirement for a single packet transmission is a block error rate (BLER) of 1E-5 for a packet size of 32 bytes with a user plane latency of 1 ms.

[0034] From a physical layer perspective, reliability can be improved in many possible ways. Current room for reliability improvement includes defining a separate CQI table for URLLC, more compact DCI formats, PDCCH repetition, etc. However, this room can be expanded to achieve ultra-high reliability as NR becomes more stable and more developed (with respect to the key requirements of NR URLLC). Specific use cases for NR URLLC in Release 15 include augmented reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0035] Also, technology enhancements targeted by NR URLLC aim to improve latency and reliability. Technology enhancements for latency improvement include configurable numerology, minislot-based scheduling with flexible mapping, grant-free (configured grant) uplink, minislot-level repetition in data channel, and pre-emption in downlink. Pre-emption means that a transmission for which resources have already been allocated is stopped and the already allocated resources are used for other transmissions with lower latency / higher priority requirements that are requested later. Thus, a transmission that was already allowed is preempted by a later transmission. Pre-emption is applicable regardless of the specific service type. For example, a transmission of service type A (URLLC) can be preempted by a transmission of service type B (eMBB, etc.). Technology enhancements for reliability improvement include dedicated CQI / MCS tables for a target BLER of 1E-5.

[0036] The use case of mMTC (massive machine type communication) is characterized by a very large number of connected devices that typically transmit relatively small amounts of data that are not sensitive to delays. The devices are required to be low cost and have a very long battery life. From an NR perspective, the use of very narrow bandwidth portions is one solution that saves power from the UE's perspective and allows for a long battery life.

[0037] As mentioned above, the scope of reliability improvement in NR is expected to be broader. One of the key requirements for all cases, especially for URLLC and mMTC, is high or ultra-high reliability. Several mechanisms can improve reliability from a radio perspective and a network perspective. In general, there are two to three key areas that can help improve reliability. These areas include compact control channel information, data channel / control channel repetition, and diversity with respect to frequency, time, and / or spatial domains. These areas are generally applicable to reliability improvement regardless of the specific communication scenario.

[0038] Further use cases with more stringent requirements are envisaged for NR URLLC, such as factory automation, transportation, and power distribution. The stringent requirements include high reliability (10 -6 level of reliability), high availability, packet size up to 256 bytes, time synchronization up to a few μs (depending on the use case, the value can be 1 μs or a few μs depending on the frequency range and short latency on the order of 0.5 ms to 1 ms (in particular, a targeted latency of 0.5 ms on the user plane).

[0039] Furthermore, for NR URLLC, there are several possible technology enhancements from the physical layer point of view. These include PDCCH (Physical Downlink Control Channel) enhancements for compact DCI, PDCCH repetition, and increased PDCCH monitoring. Also, UCI (Uplink Control Information) enhancements relate to enhanced HARQ (Hybrid Automatic Repeat Request) and CSI feedback enhancements. Also, there may be PUSCH enhancements related to minislot level hopping, and retransmission / repetition enhancements. The term "minislot" refers to a Transmission Time Interval (TTI) that contains fewer symbols than a slot (a slot comprises 14 symbols).

[0040] 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 (Guaranteed Bit Rate) QoS flows) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flows). Thus, at the NAS level, a QoS flow is the finest granularity of QoS classification in a PDU session. A QoS flow is identified in a PDU session by a QoS Flow ID (QFI) that is carried in the encapsulation header over the NG-U interface.

[0041] For each UE, the 5GC establishes one or more PDU sessions. For each UE, the NG-RAN establishes at least one Data Radio Bearer (DRB) for the PDU session, e.g. as shown above with reference to Fig. 3. Additional DRBs for the QoS flows of that PDU session can be configured later (when it is up to the NG-RAN). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. The NAS level packet filters in the UE and 5GC associate UL and DL packets with QoS flows, whereas the AS level mapping rules in the UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0042] Figure 5 shows a non-roaming reference architecture for 5G NR (see Section 4.2.1.1 of Non-Patent Document 6). An Application Function (AF) (e.g., an external application server hosting 5G services as illustrated in Figure 4) interacts with the 3GPP core network to support the provision of services, e.g., application influence on traffic routing, access to a Network Exposure Function (NEF), or interacting with a policy framework for policy control (e.g., QoS control) (see Policy Control Function (PCF)). Based on the operator's deployment, an Application Function that is considered trusted by the operator can interact directly with the relevant Network Function. An Application Function that is not allowed by the operator to directly access a Network Function interacts with the relevant Network Function using an external release framework via the NEF.

[0043] Figure 5 further illustrates further functional units of the 5G architecture for V2X communication, namely Unified Data Management (UDM), Policy Control Function (PCF), Network Exposure Function (NEF), Application Function (AF), Unified Data Repository (UDR), Access and Mobility Management Function (AMF), Session Management Function (SMF), and User Plane Function (UPF) in 5GC, as well as 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 deployed and run in a cloud computing environment.

[0044] The problem to be solved in this disclosure is that there is no specification on how to perform multi-PRACH transmission across multiple ROs in NR. If a UE attempts to perform single PRACH transmission within one slot (legacy UE functionality) or multiple PRACH transmission across multiple slots (Rel.18 UE functionality) by attempting multiple ROs based on the same PRACH resource, the PRACH detection performance is not desirable because the gNB does not recognize the multi-PRACH transmission from the UE.

[0045] A prior art solution to this problem based on PRACH detection as defined in 3GPP TS 7 in current NR is shown in diagram 700 of FIG. 7. When multiple PRACH transmissions are performed by the UE (e.g. to achieve selective gain in the time domain), the gNB tries to detect the PRACH preamble from the multiple PRACH transmissions multiple times in the time domain (e.g. as shown in the first PRACH detection attempt 702 to the m-th PRACH detection attempt 704) without knowing about the multiple PRACH transmissions. From the gNB's point of view, there is no difference between the PRACH resources of a single PRACH transmission or multiple PRACH transmissions in this solution. The selective gain is smaller compared to the case with a dedicated multiple PRACH transmission due to the near-far problem. The use of either energy accumulation or coherent accumulation is difficult because it is not clear which PRACH resource corresponding to the n-th transmission is used. Note that coherent accumulation requires high gNB complexity.

[0046] According to the solution proposed in the present disclosure to address the above-mentioned problems, the UE performs multiple PRACH transmissions based on control information regarding a multiple PRACH transmission pattern (embodiment E1) or a RACH occasion (RO) of the multiple PRACH transmission (embodiment E2). The multiple PRACH transmission pattern or the RO of the multiple PRACH transmission may be different for each CE level. If the RO of the multiple PRACH transmission is associated by the control information, the multiple PRACH transmission may be implicitly determined from the RO. To ensure energy accumulation, the gNB's PRACH detection, which provides low complexity and reasonable detection gain, may be utilized. If the UE transmission is specified to be a coherent multiple PRACH transmission, coherent accumulation may also be used. By setting multiple CE levels, noise levels can be distinguished according to the requirements of the number of PRACH transmissions. Compared with the above-mentioned conventional solutions, the proposed solution advantageously achieves better performance improvement of coverage.

[0047] In embodiment E1, the UE receives a multi-PRACH transmission pattern (K≧1 slot) for each CE level to determine a RACH occasion (RO) for each PRACH transmission of a plurality of PRACH transmissions (e.g., multi-PRACH transmissions) according to the CE level. The multi-PRACH transmission patterns for each CE level may be different from each other. For example, the multi-PRACH transmission pattern for a lower CE level (e.g., CE level 1) may have fewer ROs for transmissions included in it than the multi-PRACH transmission pattern for a higher CE level (e.g., CE level 2). With regard to the examples shown in diagrams 800 and 812 of FIG. 8A and FIG. 8B, l0=0 (as will be further described in the following paragraphs, the formula l for deriving the starting position of the RO is i =l0+iN dur RA 814) and an A3 preamble of length 6 symbols, with K=2 slots for CE level 1 (see reference numeral 814) and K=3 slots for CE level 2 (see reference numeral 816).

[0048] Due to overlap with a slot boundary (e.g., the boundary of two slots as shown in reference numbers 808 and 810), the UE may drop one PRACH transmission 802 for CE level 1 and two PRACH transmissions 804 and 806 for CE level 2. This may be advantageous for slot-level Frequency Hopping (FH) interworking purposes, or in the flexible case where the UE may be configured by the gNB to accept power control commands at the start of a slot, or in the flexible case where the UE may be configured by the gNB to monitor and / or receive the PDCCH at the start symbol of a slot.

[0049] Instead of using the term "multiple PRACH transmissions per CE level," it will be appreciated that there may be multiple PRACH transmissions per PRACH transmission repetition count, per one or more Reference Signal Receive Power (RSRP) thresholds (e.g., thresholds such as those shown in RSRP threshold 1 818 and RSRP threshold 2 820), or per other criteria configurable by the associated gNB.

[0050] According to a modification of the embodiment E1, symbol units N dur RA The UE may be configured to derive an RO for each of the multiple PRACH transmissions, including the PRACH length (i.e., the duration length of each of the multiple PRACH transmissions according to the PRACH preamble format) and a starting position. The starting position may be based on any of the following alternatives:

[0051] In alternative 1.1, the starting position of RO- for each of the multiple PRACH transmissions is derived by fitting the multiple PRACH transmissions within K slots, for example as shown in Figure 8A.

number

[0052] In alternative 1.2, in a first slot of K slots, the starting positions of the ROs of a subset of PRACH transmissions are derived by fitting these ROs within the first slot. These starting positions of the ROs are repeated in the remaining (K-1) slots as shown in the diagram 900 of FIG. 9. In the first slot 902 of the K slots, with K=2 slots for CE level 1 and K=3 slots for CE level 2, a 6-symbol l0=0 and A3 preamble and two PRACH transmissions 904 and 906 are defined, which are repeated in the following (K-1) slots. In this case,

number

[0053] In a further variant of embodiment E1, within the K slots, one or more smaller sub-patterns may be determined based on one or more of the following: First, in alternative 2.1, in collision handling between derived ROs of one or more PRACH transmissions that overlap with slot boundaries and / or signals (or channels) of different priorities, the UE may only drop the overlapping one or more PRACH transmissions and keep the remaining PRACH transmissions to be transmitted. Signals (or channels) with different priorities may refer to downlink receptions or uplink transmissions with higher priorities (e.g., reception of SSBs or reception of PDCCH for URLLC services). Within a multi-PRACH transmission pattern, the number of PRACH transmissions per slot may be the same or different from each other (e.g., an example of using both alternatives 1.1 and 2.1 in collision handling by slot boundaries as shown in diagram 800 of FIG. 8A). Advantageously, this is useful for interworking purposes with slot-level based frequency hopping (FH), i.e., a multi-PRACH transmission pattern may include multiple FH hops, and coherent PRACH detection can be performed for each FH hop for frequency selective gain.

[0054] In another alternative 2.2, for collision handling between derived ROs of one or more PRACH transmissions with slot boundaries and / or different priority signals (or channels), the UE may generate a PRACH preamble for each of the one or more PRACH transmissions and transmit all PRACH transmissions of the multiple PRACH transmissions. An example of using both alternatives 1.1 and 2.2 is shown in the embodiment 1000 of FIG. 10 for collision handling at slot boundaries. For example, referring to the illustration 1000, l0=0 and an A3 preamble of length 6 symbols is used, with K=2 slots for CE level 1 and K=3 slots for CE level 2. The UE performs 4 PRACH transmissions 1002 and 7 PRACH transmissions 1004 for CE level 1 and CE level 2, respectively. Advantageously, this allows the UE to have more possibilities of PRACH transmissions within K slots, resulting in higher gains for detection. Secondly, the maximum duration of UE capabilities is utilized to maintain phase continuity and power consistency.

[0055] In embodiment E2, the UE may be configured to receive a notification indicating an RO for the transmission of the multiple PRACHs. Upon receiving the notification, the UE determines the multiple ROs for the multiple PRACH transmission based on a legacy procedure. In this case, the multiple PRACH transmission pattern is implicitly determined from the indicated RO.

[0056] There may be various ways of signaling for the notification. In option 1, the notification may be done by higher layer parameters in the Master Information Block (MIB) and / or System Information Block (SIB). Fig. 11A shows an illustration 1100 of higher layer parameters indicating RO for multi-PRACH transmission according to embodiment E2. This is an example of higher layer parameters indicating RO for multi-PRACH transmission (see 1102), where PRACH length depends on Preamble_Format (see 1104), the start position of each RO is defined by Start_Position_in_RACH_slot (see 1106), and the number of PRACH transmissions is obtained by numberOfPRACH_Repetitions (see 1108). In option 2, table-based notification may be used, where the current table for random access configuration is extended by adding a new entry to indicate RO for multi-PRACH transmission. The extended table may be configured or pre-configured as shown in table 1110 of FIG. 11B. Table 1110 is an example of Table 6.3.3.2-3 (random access configuration for frequency range 1 (FR1) and unpaired spectrum) of 3GPP TS 2010-201306 (see part 1112 of the table) extended to signal RO for multi-PRACH transmission. In table 1110, the current higher layer parameter prach-ConfigurationIndex is reused to indicate the row of the table. The UE may receive the PRACH duration N according to the legacy procedure. dur RA and determining the starting position of each of the multiple ROs. It will be appreciated that option 1 and option 2 may also be used in combination to indicate the ROs of multiple PRACH transmissions.

[0057] It is also possible to implement general variations on the embodiments E1 and E2, where the dedicated PRACH resources for multi-PRACH transmissions configured based on the CE level include dedicated radio resources and / or PRACH preambles. As an example, the diagram 1200 of Fig. 12 shows a preamble split for two CE levels. Separate R1 and R2 preambles (reference numbers 1202 and 1204, respectively) are configured per RO for CE levels 1 and 2. The UE can use the same frequency resource allocation to transmit either one of the R1 preambles or either one of the R2 preambles. In another example, the diagram 1300 of Fig. 13 shows a frequency division multiplexed (FDM) split for different CE levels per RO and a subcarrier offset for CE levels 1 and 2, respectively. The same set of R preambles is used for both CE levels of the RO, but the UE can select one of the R preambles using different frequency allocations for different CE levels. For example, RO#3 may be configured to use subcarrier offset 1302 for CE level 1 and subcarrier offset 1304 for CE level 2.

[0058] Another problem to be solved in this disclosure is that it is not yet specified how multi-PRACH transmission for UEs with different BW capabilities should be performed. Both of the embodiments E1 and E2 cannot be directly applied to XDD UEs and RedCap UEs when the BW of the RO for multi-PRACH transmission is wider than the BW set for XDD and the maximum BW of RedCap UEs, respectively.

[0059] Rel-17 NR supports Reduced Capability (RedCap) UEs with reduced maximum BW (20 MHz for FR1 and 100 MHz for FR2). If the initial uplink (UL) bandwidth portion (BWP) (e.g., BWP for non-RedCap UE) is wider than the maximum BW of RedCap UE, a separate initial UL BWP (e.g., in the illustration 1400 of FIG. 14, a separate UL BWP 1402 is configured for RedCap UE and a separate UL BWP 1404 is configured for non-RedCap UE) for RedCap UE within the maximum BW of RedCap UE is always configured during initial access. Inside the separate initial UL BWP, an RO for RedCap UE is configured.

[0060] Additionally, a new study item on cross-division duplex (XDD) has been approved in RAN#94-e [RP-213591] to explore potential extensions in sub-band non-overlapping full duplex (SBFD) and dynamic / flexible time-division duplex (TDD). In NR, the slot / frame format includes downlink (DL) symbols (or slots), uplink (UL) symbols (or slots), and flexible (F) symbols (or slots), with DL / UL configuration restrictions to avoid UL / DL interference between gNBs and UEs, while only F symbols (or slots) are further configurable, semi-statically or dynamically, to either DL symbols (or slots) or UL symbols (or slots). For example, referring to diagram 1500 in FIG. 15, in Release 15 / 16 / 17, F symbols (or slots) are configured as UL symbols (or slots) (see 1504). In XDD, in F symbols (or slots), some UEs can be further configured as DL and other UEs can be further configured as UL, so that the serving cell band is divided into multiple sub-bands (BW XDD) can be set in F symbols (or slots) in the time domain. For example, as shown in diagram 1500 of FIG. 15, frequency resource allocation for each F symbol (or slot) is flexibly set for UE#1 and UE#2. Depending on the application, multiple downlink receptions for UE#1 (see 1506) and few uplink transmissions for UE#2, or multiple uplink transmissions for UE#2 (see 1508) and few downlink receptions for UE#1 are set. On the gNB side, (quasi-) full-duplex communication is required, but half-duplex communication is available on the UE side.

[0061] Furthermore, Rel-17 NR supports Reduced Capability (RedCap) UEs with reduced maximum BW (20 MHz for FR1 and 100 MHz for FR2). If the initial uplink (UL) bandwidth portion (BWP) (e.g., BWP for non-RedCap UE) is wider than the maximum BW of RedCap UE, a separate initial UL BWP (e.g., in the illustration 1400 of FIG. 14, a separate UL BWP 1402 is configured for RedCap UE and a separate UL BWP 1404 is configured for non-RedCap UE) for RedCap UE within the maximum BW of RedCap UE is always configured during initial access. Within the separate initial UL BWP, RO for RedCap UE is configured.

[0062] Additionally, a new study item on cross-division duplex (XDD) has been approved in RAN#94-e [RP-213591] to explore potential extensions in sub-band non-overlapping full duplex (SBFD) and dynamic / flexible time-division duplex (TDD). In NR, the slot / frame format includes downlink (DL) symbols (or slots), uplink (UL) symbols (or slots), and flexible (F) symbols (or slots), with DL / UL configuration restrictions to avoid UL / DL interference between gNBs and UEs, while only F symbols (or slots) are further configurable, semi-statically or dynamically, to either DL symbols (or slots) or UL symbols (or slots). For example, referring to diagram 1500 in FIG. 15, in Release 15 / 16 / 17, F symbols (or slots) are configured as UL symbols (or slots) (see 1504). In XDD, the serving cell band is divided into multiple sub-bands (BW XDD ) is configurable in F symbols (or slots) in the time domain. This is because in F symbols (or slots), some UEs can be further configured as DL, while some other UEs can be further configured as UL. For example, as shown in the diagram 1500 of FIG. 15, frequency resource allocation per F symbols (or slots) is flexibly configured for UE#1 and UE#2, and depending on the application, multiple downlink receptions for UE#1 (see 1506) and few uplink transmissions for UE#2, or multiple uplink transmissions for UE#2 (see 1508) and few downlink receptions for UE#1 are configured. On the gNB side, (quasi-) full-duplex communication is required, but half-duplex communication is available on the UE side.

[0063] In embodiment E3, the UE is configured to have a reduced frequency resource allocation per RO for multi-PRACH transmission or a reduced frequency resource allocation for all ROs according to one of the following conditions: - Multiple sub-bands (BW) into which the serving cell band is divided XDD ) is narrower than the threshold (eg, for a UE operating in SBFD / XDD as shown in diagram 1600 of FIG. 16). - A first UL band that is narrower than the second UL band of SBFD / XDD. - The maximum bandwidth of the UE is narrower than the threshold (for example, for a RedCap UE as shown in diagram 1700 of FIG. 17, a separate initial UL BWP for RedCap is set within the maximum bandwidth of the RedCap UE. Within the separate initial UL BWP, the RO for the RedCap UE is determined).

[0064] The threshold may be the configured initial UL BWP. Furthermore, the configured initial BWP can be replaced by a Resource Block (RB) set, a subband set into which the serving cell band is divided, the total bandwidth of the RO frequency division multiplexed (FDMed) at the temporary instance currently configured by the higher layer parameter msg1-FDM, or other values ​​configured by the gNB. Advantageously, the solution proposed by embodiment E3 improves the coverage performance of UEs with different BW capabilities. It will be understood that UL BWP and UL band may be used interchangeably.

[0065] In the example of Fig. 16, the small frequency resource allocation of all ROs is BW in the time domain. XDD For example, the small frequency resource allocation per RO is within the BW XDD This function is determined based on FperRO XDD =FperRO nonXDD ×BW XDD / iBWP nonXDDFperRO nonXDD is the bandwidth of the RO for non-XDD UEs, and iBWP nonXDD is the configured initial UL BWP for a non-XDD UE. Referring to FIG. 16, iBWP nonXDD 1602 is generally BW XDD 1604. This is applicable when the time domain resource includes semi-static flexible symbols / flexible slots. For simplicity, the BW is also used for a set of consecutive flexible slots and / or uplink slots. XDD The same values ​​of can be applied.

[0066] Or, XDD has two or more UL bands, as shown in the right of Figure 16. For example, the first UL band of BW_XDD (i.e., at the second time symbol / time slot) is narrower than the second UL band (i.e., at the third time symbol / time slot). In this case, less frequency resources of all ROs are assigned to the first UL band (the second time symbol / time slot), and more frequency resources of all ROs are assigned to the second UL band (the third time symbol / time slot).

[0067] If the initial UL BWP of a non-RedCap UE is wider than the maximum BW of a RedCap UE, a separate initial UL BWP for the RedCap UE within the maximum BW is set during initial access. The RO for RedCap is determined within the separate initial UL BWP (not within the initial UL BWP of the non-RedCap UE). In the example shown in FIG. 17, for the RedCap UE, the smaller frequency resource allocation of the entire RO is contained within a separate initial UL BWP. This is called FperRO. RedCap =FperRO nonRedCap ×(siBWP RedCap ) / (iBWP nonRedCap ) and FperRO RedCap and FperRO nonRedCapare the bandwidths of the RO for RedCap UE and non-RedCap UE at a time instance, respectively, and siBWP RedCap is a separate initial UL BWP for RedCap UE, iBWP RedCap is the initial UL BWP for non-RedCap UE. Subcarrier offset of RedCap UE SubcarrierOffset_CE(i,j) RedCap can be set individually or the subcarrier offset for non-RedCap UE, SubcarrierOffset_CE(i,j) nonRedCap It can also be implicitly derived from SSB-to-RO mapping for RedCap UEs. The SSB-to-RO mapping for RedCap UEs is the same as for non-RedCap UEs. For example, referring to FIG. 17, a separate initial UL BWP 1702 for RedCap UEs has less frequency resource allocation than the initial UL BWP 1704 for non-RedCap UEs, but both BWPs have the same SSB-to-RO mapping of 1 / 2.

[0068] Therefore, if the initial UL BWP for a non-RedCap UE is less than or equal to the maximum BW of the RedCap UE, either of the embodiments E1 or E2 can be used to determine the RO for the multi-PRACH transmission for the RedCap UE in the same manner as for the non-RedCap UE. If the initial UL BWP for a non-RedCap UE is wider than the maximum BW of the RedCap UE, either of the embodiments E1 or E2 is used to determine the RO for the multi-PRACH transmission for the non-RedCap UE in the initial UL BWP, although the embodiment E3 can be used to determine the RO for the multi-PRACH transmission for the RedCap UE in a separate initial UL BWP.

[0069] Also, in a variation of embodiment E3, a different SSB-to-RO mapping is proposed for the UE. For example, referring to the diagram 1800 of FIG. 18, in the initial UL BWP 1802 of a RedCap UE or in a small uplink band of an XDD UE, the SSB-to-RO mapping 1806 is 1 (e.g., each SSB is mapped to one RO), whereas in the initial UL BWP 1804 of a non-RedCap UE or in a large uplink band of an XDD UE (e.g., a legacy UE or a normal Release 15 / 16 / 17 UE), the SSB-to-RO mapping 1808 is 1 / 2 (e.g., each SSB is mapped to two ROs).

[0070] Alternatively, more time domain ROs are proposed to the UE. Referring to the diagram 1900 of FIG. 19A, multi-PRACH transmissions are made by RedCap UEs at time instances t_0 (see 1902) and t_1 (see 1904) and by non-RedCap UEs at time instance t_0 (see 1906). This advantageously provides more processing time for RedCap UEs to transmit, since RedCap UEs have limited capabilities compared to non-RedCap UEs. This also allows RedCap UEs to change the coarse direction in the time domain using hybrid beamforming or analog beamforming, thereby forming finer beams within the coarse direction in the frequency domain to transmit the preamble (e.g., a first coarse direction includes SSB#0 and SSB#1 beams at t_0, and a second coarse direction includes SSB#2 and SSB#3 beams at t_1). This may provide better reception of the gNB.

[0071] Furthermore, in another variation of embodiment E3, the number of ROs in each time instance (e.g., symbols / slots at t_0 and t_1 as described above, or the second and third time symbols / slots as described above) may be set to be different. For example, referring to diagram 1908 of FIG. 19B, a threshold may be set so that all ROs are assigned to multiple subbands BW XDD The bandwidth does not fit within the bandwidth of the UL BWP or within the bandwidth of a separate initial UL BWP for the RedCap UE. XDD A subset of ROs that fall within the bandwidth of or within a separate initial UL BWP for RedCap UEs (e.g., RO#0, RO#1, RO#2, RO#s3, and RO#4 as shown in RO subset 1910) are transmitted at t_0, while the remaining ROs (e.g., RO#5, RO#6, and RO#7 as shown in RO subset 1912) are transmitted at t_1 1916.

[0072] Alternatively, the number of ROs in the small UL (sub)band in XDD may be small in one time symbol / time slot, and the number of ROs in the large UL (sub)band in XDD may be large in one time symbol / time slot. As an example, ROs may be distributed to more time symbols / time slots in the small UL (sub)band in XDD than in the large UL (sub)band in XDD. For example, a subset of ROs (such as RO#0, RO#1, RO#2, RO#s3, and RO#4 in RO subset 1910) whose bandwidth falls within the small UL (sub)band are transmitted at t_0 1914 in the small UL (sub)band in XDD. Meanwhile, the remaining ROs (such as RO#5, RO#6, and RO#7 in RO subset 1912) are transmitted at t_1 1916 in the small UL (sub)band in XDD.

[0073] Also, the SSB-to-RO mapping may be the same or different between the smaller UL (sub)band and the larger UL (sub)band. Alternatively, the SSB-to-RO mapping of the smaller UL (sub)band may be the same as the SSB-to-RO mapping of a portion of the larger UL (sub)band. That portion of the larger UL band may be at the same frequency as the smaller UL (sub)band. The SSB-to-RO mapping of the other portion of the larger UL (sub)band may be omitted (dropped) or not defined in the smaller UL (sub)band.

[0074] Also, in any of the embodiments E1 to E3, during a multi-PRACH transmission pattern, the UE may be configured to keep power consistency and phase continuity for asynchronous detection of PRACH. Furthermore, the UE may be configured to perform multiple PRACH transmissions by using the same beam, called PRACH repetition. PRACH repetition can be performed with a power ramping step based on the following alternatives: In the first alternative, PRACH repetition starts only after the UE reaches the maximum transmit power. When at the maximum transmit power, the UE increases the number of PRACH transmissions transmitted (configurable). If the number of PRACH repetitions reaches the maximum value and there is still no response from the gNB, the process fails. In the second alternative, PRACH repetition starts before the UE reaches the maximum transmit power. For example, the UE may start the PRACH repetition at a transmit power p i In the case of failure, the UE stops the PRACH transmission with a power ramping step p i =p i +Δ (where Δ is configurable) multiple times. If the transmit power reaches the maximum value and there is still no response from the gNB, the process fails.

[0075] In all embodiments, during a multi-PRACH transmission pattern, the UE may be configured to perform multi-PRACH transmissions by using different beams, called "PRACH sweeping". The UE sweeps different beams for multiple PRACH transmissions to find the optimal narrow Tx beam pair before any RRC configuration. The UE does not maintain power consistency and phase continuity during a multi-PRACH transmission pattern. The associated gNB then performs only power addition between PRACH transmissions and the gNB signals in Msg2 the best narrow Tx beam index to be used by the UE in the subsequent steps for the PRACH procedure, i.e., Msg3 transmission.

[0076] In all embodiments, a multi-PRACH transmission pattern also means multi-PRACH transmission windows / multi-PRACH transmission times / multi-PRACH transmission period.

[0077] In all embodiments, a combination of preamble formats (eg, formats A and B) may be used within a multi-PRACH transmission pattern to utilize time domain resources.

[0078] Also, in either embodiment, the energy accumulation can be performed at the gNB, in which case the UE does not need to have coherent multiple PRACH transmissions.

[0079] FIG. 20A shows an example flow chart for a UE operation with a multi-PRACH transmission pattern configured according to embodiment E1. In step 2002, the UE is configured with a multi-PRACH transmission pattern (K≧1 slot) per CE level. In step 2004, the UE derives a RACH occasion (RO) for the multi-PRACH transmission pattern at the CE level that depends on the RSRP threshold. In step 2006, it is determined whether the RO of one or more PRACH transmissions overlaps with a slot boundary. If it is determined that there is an overlap, the process proceeds to step 2008, where the UE drops one or more PRACH transmissions but maintains the remaining PRACH transmissions. If there is no overlap, the process instead proceeds to step 2010, where the UE maintains all PRACH transmissions. In step 2012, the UE performs all of the remaining PRACH transmissions or multi-PRACH transmissions.

[0080] FIG. 20B shows a flowchart of a UE operation in embodiment E2. In step 2016, the UE receives a notification indicating an RO for each PRACH transmission of the multiple PRACH transmissions (e.g., multi-PRACH transmission). In step 2018, the UE determines multiple ROs for the multi-PRACH transmissions per CE level. Each CE level depends on an RSRP threshold based on a legacy procedure. In step 2020, the UE transmits multiple PRACH transmissions based on the determined multiple ROs.

[0081] FIG. 20C shows a flowchart 2022 for RedCap UE operation according to embodiment E3. It is a general flowchart for a RedCap UE that can access a serving cell according to an initial UL BWP set by a gNB for a non-RedCap UE. In step 2024, the gNB sets the initial UL BWP and a separate initial UL BWP only for the RedCap UE. In step 2026, it is determined whether the initial UL BWP is wider than the maximum BW of the RedCap UE. If it is determined to be wider, the process proceeds to step 2030, where a two-step method is used to determine an RO for multiple PRACH transmission for the RedCap UE. In step 1, either embodiment E1 or embodiment E2 is performed to formulate an RO for multiple PRACH transmission for the non-RedCap UE. In step 2, an allocation of less frequency resources per RO is set for the RedCap UE in a separate initial UL BWP than for the non-RedCap UE. On the other hand, if it is determined in step 2026 that the initial UL BWP is not wider than the maximum BW of the RedCap UE, the process proceeds to step 2028 and determines the RO for multiple PRACH transmissions for RedCap UEs and non-RedCap UEs in the shared initial UL BWP using either embodiment E1 or embodiment E2. From either step 2028 or step 2030, the process proceeds to step 2032, where the RedCap UE transmits multiple PRACH transmissions in the shared initial UL BWP (from step 2028) or in separate UL BWPs (from step 2030).

[0082] 21 shows a flow diagram 2100 illustrating a method of communication in accordance with various embodiments. In step 2102, control information for a multi-PRACH transmission is received. In step 2104, a multi-PRACH transmission including multiple PRACH transmissions is transmitted based on the control information.

[0083] Figure 22 illustrates a partial schematic diagram of a communication device 2200 that may be implemented according to the various embodiments and examples shown in Figures 1 to 21. The communication device 2200 may be implemented as a UE according to the various embodiments.

[0084] Various functions and operations of the communication device 2200 are arranged in layers according to a hierarchical model, in which lower layers report to and receive instructions from higher layers according to 3GPP specifications, and for the sake of brevity, the details of the hierarchical model are not described in this disclosure.

[0085] As shown in FIG. 22, the communication device 2200 may include a circuit 2214, at least one wireless transmitter 2202, at least one wireless receiver 2204, and at least one antenna 2212 (for simplicity, only one antenna is shown in FIG. 22 for illustrative purposes). The circuit 2214 may include at least one controller 2206. The controller 2206 is used to perform the tasks that the at least one controller 2206 is designed to perform with the assistance of software and hardware. The tasks include controlling communication with one or more other communication devices in a wireless network. The circuit 2214 may further include at least one transmit signal generator 2208 and at least one receive signal processor 2210. The at least one control unit 2206 may control at least one transmission signal generating unit 2208 for generating a signal (e.g., a signal indicating a geographical area) to be transmitted to one or more other communication devices via the at least one wireless transmitting unit 2202, and at least one reception signal processing unit 2210 for processing a signal (e.g., a signal indicating a geographical area) received from one or more other communication devices via the at least one wireless receiving unit 2204 under the control of the at least one control unit 1506. The at least one transmission signal generating unit 2208 and the at least one reception signal processing unit 2210 may be standalone modules of the communication device 2200 that communicate with the at least one control unit 2206 for the above-mentioned functions, as shown in FIG. 22. Alternatively, the at least one transmission signal generating unit 2208 and the at least one reception signal processing unit 2210 may be included in the at least one control unit 2206. It is obvious to those skilled in the art that the arrangement of these functional modules is flexible and may be changed according to actual needs and / or requirements. Data processing, virtual storage, and other related controls may be provided on an appropriate circuit board and / or within a chipset. In various embodiments, in operation, the at least one wireless transmitter 2202, the at least one wireless receiver 2204, and the at least one antenna 2212 may be controlled by the at least one controller 1506.

[0086] The communications apparatus 2200, in operation, provides functionality required for multiple PRACH transmissions with limited bandwidth. For example, the communications apparatus 2200 may be a UE, and the receiver 2204, in operation, may receive control information related to the multiple PRACH transmissions. The transmitter 2202, in operation, may transmit the multiple PRACH transmissions including the multiple PRACH transmissions based on the control information.

[0087] The control information may indicate a multi-PRACH transmission pattern for the one or more transmission slots, and the transmitter 2202 may be further configured to transmit the multi-PRACH transmissions across the one or more transmission slots based on the multi-PRACH transmission pattern.

[0088] The control information may further indicate a different multi-PRACH transmission pattern for each of one or more Coverage Enhancement (CE) levels, and the circuitry 2214, in operation, may be further configured to determine a CE level for the multi-PRACH transmission, and the transmitter 2202 may be further configured to transmit the multi-PRACH transmission based on the multi-PRACH transmission pattern corresponding to the determined CE level.

[0089] The control information may further indicate a different number of transmission slots for each of one or more CE levels, and the transmitter 2202 may be further configured to transmit a multi-PRACH transmission within the number of transmission slots corresponding to the determined CE level.

[0090] In operation, the circuit 2214 may determine a duration and a starting position of each PRACH transmission of the multi-PRACH transmission within one or more transmission slots, and the transmitter 2202 may be further configured to transmit the multi-PRACH transmission based on the determined duration and starting position. The circuit 2214 may be further configured to determine one or more smaller sub-patterns in the multi-PRACH transmission pattern if a condition is met, the condition being to handle collisions between any PRACH transmission of the multi-PRACH transmission and a slot boundary and / or collisions between any PRACH transmission of the multi-PRACH transmission and other uplink transmissions or downlink receptions with higher priority.

[0091] The circuit 2214, in operation, may be further configured to identify one or more PRACH transmissions of the multi-PRACH transmission across one or more slot boundaries of the one or more transmission slots, and the transmitter 2202 may be further configured to transmit the multi-PRACH transmission across the one or more transmission slots, excluding the identified one or more PRACH transmissions.

[0092] The circuitry 2214, in operation, may be further configured to identify one or more PRACH transmissions of the multi-PRACH transmission across one or more slot boundaries of the one or more transmission slots and generate a PRACH preamble for each of the multi-PRACH transmissions including the identified one or more PRACH transmissions, and the transmitter 2202 may be further configured to transmit the multi-PRACH transmission including transmitting the identified one or more PRACH transmissions across the one or more slot boundaries.

[0093] The control information may indicate multiple RACH Occasions (ROs) for the multi-PRACH transmission, and the transmitter 2202 may be further configured to transmit the multi-PRACH transmission based on the indicated ROs. The control information may be indicated by any one or combination of downlink control information, table-based information, uplink control information, a Medium Access Control Element (MAC CE), or a Radio Resource Control (RRC).

[0094] The control information may indicate one or more beams for uplink transmission, and the transmitter 2202 may be further configured to transmit the multi-PRACH transmission using only one of the indicated beams or beams. The control information may indicate one or more beams for uplink transmission, and the transmitter 2202 may be further configured to transmit the multi-PRACH transmission using a subset of the indicated beams or beams. The transmitter 2202 may be further configured to transmit the multi-PRACH transmission only after the communications device has reached a maximum transmit power.

[0095] The communications device 2200 may be, for example, a base station, and the circuitry may, upon operation, generate control information for the multi-PRACH transmission. The transmitter 2202, upon operation, may transmit the control information to the communications device. The receiver 2204, upon operation, may receive the multi-PRACH transmission from the communications device.

[0096] (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).

[0097] The uplink control signal (information) according to the present disclosure may be a signal (information) transmitted via a PUCCH of a physical layer, or may be a signal (information) transmitted via a MAC CE of a higher layer or an RRC. The uplink control signal may be a signal (information) defined in advance. The uplink control signal may be uplink control information (UCI), first stage sidelink control information (SCI), or second stage SCI.

[0098] (base station) In the present disclosure, the base station may be, for example, a Transmission Reception Point (TRP), a cluster head, an access point, a Remote Radio Head (RRH), an eNodeB (eNB), a gNodeB (gNB), a Base Station (BS), a Base Transceiver Station (BTS), a base unit, or a gateway. In addition, in sidelink communication, a terminal may be used instead of the base station. The base station may be a relay device that relays communication between an upper node and a terminal. The base station may be a roadside unit.

[0099] (Uplink / Downlink / Sidelink) The present disclosure may be applied to any of the uplink, downlink, and sidelink.

[0100] The present disclosure may be applied to, for example, uplink channels such as PUSCH, PUCCH, and PRACH, downlink channels such as PDSCH, PDCCH, and PBCH, and sidelink channels such as a physical sidelink shared channel (PSSCH), a physical sidelink control channel (PSCCH), and a physical sidelink broadcast channel (PSBCH).

[0101] 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.

[0102] (Data Channel / Control Channel) The present disclosure may be applied to both data channels and control channels. The channels in the present disclosure may be replaced with data channels including PDSCH, PUSCH, and PSSCH, and / or control channels including PDCCH, PUCCH, PBCH, PSCCH, and PSBCH.

[0103] (reference signal) In this disclosure, a reference signal is a signal known to both a base station and a mobile station, and each reference signal may be referred to as a reference signal (RS) or a pilot signal. A reference signal may be any of a DMRS, a Channel State Information - Reference Signal (CSI-RS), a Tracking Reference Signal (TRS), a Phase Tracking Reference Signal (PTRS), a Cell-specific Reference Signal (CRS), and a Sounding Reference Signal (SRS).

[0104] (Time Interval) In the present disclosure, the time resource unit is not limited to one or a combination of slots and symbols, and may be a time resource unit such as a frame, a superframe, a subframe, a slot, a subslot of a time slot, a minislot, or a symbol, an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier-Frequency Division Multiplexing Access (SC-FDMA) symbol, or other time resource unit. The number of symbols included in one slot is not limited to the number of symbols exemplified in the above-mentioned embodiment, and may be other numbers of symbols.

[0105] (Frequency band) The present disclosure may apply to both licensed and unlicensed bands.

[0106] (communication) The present disclosure may be applied to any of communication between a base station and a terminal (Uu link communication), communication between terminals (sidelink communication), and V2X (Vehicle to Everything) communication. The channels in the present disclosure may be rephrased as PSCCH, PSSCH, physical sidelink feedback channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, and PBCH.

[0107] The present disclosure can also be applied to a terrestrial network or a non-terrestrial network (NTN) using a satellite or a high altitude pseudo satellite (HAPS). The present disclosure can also be applied to a terrestrial network with a large cell size and a large delay compared to a symbol length or a slot length, such as an ultra-wideband transmission network.

[0108] (Antenna port) An antenna port refers to a logical antenna (antenna group) formed from one or more physical antennas. That is, an antenna port does not necessarily refer to one physical antenna, but may refer to an array antenna consisting of multiple antennas. For example, the number of physical antennas that constitute an antenna port is not defined, and instead, an antenna port is defined as the smallest unit that a terminal is allowed to transmit a reference signal. An antenna port may also be defined as the smallest unit for multiplication of a precoding vector weighting.

[0109] Thus, embodiments of the present disclosure provide advanced communication systems, methods, and devices for multi-PRACH transmission that advantageously provide improved performance benefits of coverage among multiple PRACH transmissions.

[0110] The present disclosure can be realized by software, hardware, or software in cooperation with hardware. Each functional block used in the description of the above embodiment can be realized partially or entirely as an LSI, which is an integrated circuit, and each process described in the above embodiment can be controlled partially or entirely by one LSI or a combination of LSIs. The LSI can be configured from individual chips, and can be configured from one chip to include some or all of the functional blocks. The LSI may have input and output of data. Depending on the degree of integration, the LSI may be called an IC, a system LSI, a super LSI, or an ultra LSI. The method of integration is not limited to LSI, and may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. In addition, a field programmable gate array (FPGA) that can be programmed after LSI manufacture, or a reconfigurable processor that can reconfigure the connection and settings of the circuit cells inside the LSI may be used. The present disclosure can be realized as digital processing or analog processing. Furthermore, if a new integrated circuit technology that can replace LSI appears due to the progress of semiconductor technology or a derivative technology, it is possible to integrate the functional blocks using that technology. The application of biotechnology is also a possibility.

[0111] The present disclosure may be implemented in any type of apparatus, device, or system having a communication capability (collectively referred to as communication apparatus).

[0112] Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones, etc.), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks, etc.), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices, etc.), game consoles, digital book readers, telehealth and telemedicine devices, communication-enabled vehicles or mobile conveyances (e.g., cars, airplanes, boats, etc.), and combinations of the above devices.

[0113] Communications Equipment is not limited to portable or mobile, but also includes non-portable or fixed equipment, devices and systems of any kind, such as smart home devices (appliances, lighting, smart meters or metering devices, control panels, etc.), vending machines and any other "Things" that may be present on an Internet of Things (IoT) network.

[0114] Communications include data communications via cellular systems, wireless LAN systems, communications satellite systems, etc., as well as data communications via combinations of these.

[0115] A communications apparatus also includes devices, such as controllers and sensors, connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0116] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0117] Although some features of the various embodiments are described with reference to a device, it will be understood that the corresponding features also apply to the methods of the various embodiments, and vice versa.

[0118] Further described below are descriptions that apply to various embodiments of the present invention.

[0119] statement 1 A communications device comprising: a receiver that, during operation, receives control information related to a multi-PRACH transmission; and a transmitter that, during operation, transmits a multi-PRACH transmission including a plurality of PRACH transmissions based on the control information.

[0120] statement 2 The communication device of claim 1, wherein the control information indicates a multi-PRACH transmission pattern for one or more transmission slots, and the transmitter is further configured to transmit the multi-PRACH transmission over the one or more transmission slots based on the multi-PRACH transmission pattern.

[0121] statement 3 The communication device of statement 2, wherein the control information further indicates a different multi-PRACH transmission pattern for each of one or more Coverage Enhancement (CE) levels, and the circuit, in operation, is further configured to determine the CE level for the multi-PRACH transmission, and the transmitter unit is further configured to transmit the multi-PRACH transmission based on the multi-PRACH transmission pattern corresponding to the determined CE level.

[0122] statement 4 The communication device of statement 2, wherein the control information further indicates a different number of transmission slots for each of the one or more CE levels, and the transmitter is further configured to transmit the multi-PRACH transmission within a number of the transmission slots corresponding to the determined CE level.

[0123] statement 5 3. The communications device of claim 2, further comprising a circuit that, during operation, determines a duration and a starting position of each PRACH transmission within the one or more transmission slots, the transmitter further configured to transmit the multi-PRACH transmission based on the determined duration and starting position.

[0124] statement 6 3. The communications device of claim 2, further comprising a circuit that, during operation, determines a plurality of RACH occasions (ROs) including durations and starting positions of a subset of multi-PRACH transmissions in a first slot of the one or more transmission slots, and repeats the determined RO for each remaining slot of the one or more transmission slots, wherein the transmitter is further configured to transmit the multi-PRACH transmissions via the one or more transmission slots based on the determined RO.

[0125] statement 7 3. The communications device of claim 2, further comprising a circuit for, during operation, identifying one or more PRACH transmissions of a multi-PRACH transmission across one or more slot boundaries of the one or more transmission slots, the transmitter being further configured to transmit the multi-PRACH transmission over the one or more transmission slots, excluding the identified one or more PRACH transmissions.

[0126] statement 8 3. The communications device of claim 2, further comprising a circuit that, during operation, identifies one or more PRACH transmissions of the multi-PRACH transmission across one or more slot boundaries of the one or more transmission slots and generates a PRACH preamble for each of the multi-PRACH transmissions including the identified one or more PRACH transmissions, wherein the transmitter is further configured to transmit the multi-PRACH transmission including transmitting the identified one or more PRACH transmissions across the one or more slot boundaries.

[0127] statement 9 3. The communication device of claim 2, further comprising a circuit for, during operation, determining a plurality of PRACH resources for the multi-PRACH transmission based on the multi-PRACH transmission pattern and determining a CE level for the multi-PRACH transmission, wherein the plurality of PRACH resources each include a dedicated radio resource and / or a PRACH preamble having a different CE level, and the transmitting unit transmits the multi-PRACH transmission based on each of the plurality of PRACH resources corresponding to the determined CE level.

[0128] statement 10 6. The communications device of claim 5, wherein the circuitry is further configured to determine one or more smaller sub-patterns within the multi-PRACH transmission pattern if a condition is met for handling a collision between any PRACH transmission in the multi-PRACH transmission pattern and a slot boundary and / or a collision between any PRACH transmission of the multi-PRACH transmission and other uplink transmissions or downlink receptions having a higher priority.

[0129] statement 11 11. The communication device of claim 10, wherein the condition is that the multi-PRACH transmission pattern is longer than a maximum duration for the communication device that can maintain phase continuity and power consistency.

[0130] statement 12 The communication device of claim 1, wherein the control information indicates multiple RACH occasions (ROs) for the multi-PRACH transmission, and the transmitting unit is further configured to transmit the multi-PRACH transmission based on the indicated multiple ROs.

[0131] statement 13 The communication device of claim 1, wherein the control information is signaled by any one or a combination of downlink control information, table-based information, uplink control information, a medium access control control element (MAC CE), or a radio resource control (RRC).

[0132] statement 14 The communication device of claim 1, wherein the control information indicates one or more beams for uplink transmission, and the transmitter is further configured to transmit a multi-PRACH transmission using only one of the indicated one or more beams.

[0133] statement 15 The communication device of claim 1, wherein the control information indicates one or more beams for uplink transmission, and the transmitter is further configured to transmit a multi-PRACH transmission using a subset of the indicated one or more beams.

[0134] statement 16 16. The communications device of claim 14 or 15, wherein the transmitter is further configured to transmit a multi-PRACH transmission only after the communications device has reached a maximum transmit power.

[0135] Statement 17 16. The communications device of claim 14 or 15, wherein the transmitter is further configured to transmit multiple PRACH transmissions before the communications device reaches a maximum transmit power.

[0136] statement 18 15. The communications device of claim 14, wherein the transmitter is further configured to transmit a coherent multi-PRACH transmission.

[0137] Statement 19 The communication device of claim 1, wherein the control information indicates a plurality of preamble formats, and the transmitting unit is further configured to determine a combination of preamble formats from the indicated plurality of preamble formats and transmit the multi-PRACH transmission.

[0138] statement 20 A base station comprising: a circuit that generates control information related to a multi-PRACH transmission during operation; a transmitting unit that transmits the control information to a communication device during operation; and a receiving unit that receives a multi-PRACH transmission from the communication device during operation.

[0139] statement 21 11. A communication method, comprising: receiving control information related to a multi-PRACH transmission; and transmitting a multi-PRACH transmission including a plurality of PRACH transmissions based on the received control information.

[0140] Those skilled in the art will appreciate that numerous variations and / or modifications may be made to the present disclosure as illustrated in the specific embodiments without departing from the spirit or scope of the disclosure as broadly described, and therefore, the present embodiments are to be considered in all respects as illustrative and not restrictive.

Claims

1. A communication device, comprising: A receiver that, during operation, receives control information related to multi-PRACH transmission; a transmitter that, during operation, transmits a multi-PRACH transmission including a plurality of PRACH transmissions based on the control information; A communication device comprising:

2. The control information indicates a multi-PRACH transmission pattern for one or more transmission slots. the transmitter unit is further configured to transmit the multi-PRACH transmission across the one or more transmission slots based on the multi-PRACH transmission pattern. The communication device according to claim 1 .

3. The control information further indicates a different multi-PRACH transmission pattern for each of one or more Coverage Enhancement (CE) levels; The communications device further comprises a circuit, during operation, for determining a CE level for the multi-PRACH transmission; The transmitter is further configured to transmit the multi-PRACH transmission based on a multi-PRACH transmission pattern corresponding to the determined CE level. The communication device according to claim 2 .

4. The control information further indicates a different number of transmission slots for each of the one or more CE levels. The transmitter is further configured to transmit the multi-PRACH transmission within a number of the transmission slots corresponding to a determined CE level. The communication device according to claim 2 .

5. and a circuit for determining, during operation, a duration and a starting position of each PRACH transmission of the multi-PRACH within the one or more transmission slots; The transmitter is further configured to transmit the multi-PRACH transmission based on the determined duration and start position. The communication device according to claim 2 .

6. and a circuit for, during operation, identifying one or more PRACH transmissions of the multi-PRACH transmission across one or more slot boundaries of the one or more transmission slots; the transmitter unit is further configured to transmit the multi-PRACH transmission across the one or more transmission slots, excluding the identified one or more PRACH transmissions. The communication device according to claim 2 .

7. and a circuit for, during operation, identifying one or more PRACH transmissions of the multi-PRACH transmission across one or more slot boundaries of the one or more transmission slots, and generating a PRACH preamble for each of the multi-PRACH transmissions that includes the identified one or more PRACH transmissions; the transmitter unit is further configured to transmit the multi-PRACH transmission including transmitting the identified one or more PRACH transmissions across the one or more slot boundaries. The communication device according to claim 2 .

8. the circuitry is further configured to determine one or more smaller sub-patterns within the multi-PRACH transmission pattern if a condition is met, the condition being to handle collisions between any PRACH transmission of the multi-PRACH transmission and a slot boundary and / or collisions between any PRACH transmission of the multi-PRACH transmission and other uplink transmissions or downlink receptions of higher priority. The communication device according to claim 5.

9. The control information indicates a plurality of RACH occasions (ROs) of the multi-PRACH transmission; The transmitter is further configured to transmit the multi-PRACH transmission based on the indicated multiple ROs. The communication device according to claim 1 .

10. The control information is indicated by any one or combination of downlink control information, table-based information, uplink control information, medium access control element (MAC CE), or radio resource control (RRC), The communication device according to claim 1 .

11. the control information indicating one or more beams for uplink transmission; the transmitter is further configured to transmit a multi-PRACH transmission using only one of the indicated one or more beams. The communication device according to claim 1 .

12. the control information indicating one or more beams for uplink transmission; the transmitter is further configured to transmit a multi-PRACH transmission using a subset of the indicated one or more beams. The communication device according to claim 1 .

13. The transmitter is further configured to transmit a multi-PRACH transmission only after the communication device has reached a maximum transmit power. A communication device according to claim 11 or 12.

14. a circuit for generating control information for multi-PRACH transmissions when in operation; a transmitter that, during operation, transmits the control information to a communication device; a receiver that, during operation, receives the multi-PRACH transmission from the communication device; A base station comprising:

15. receiving control information regarding multi-PRACH transmission; transmitting a multi-PRACH transmission including a plurality of PRACH transmissions based on the control information; A communication method comprising:

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