Communication apparatus and communication method for multi-PRACH transmission using a limited bandwidth

Abstract

The present disclosure provides a communication device and a communication method for multi-PRACH transmission using a limited bandwidth. The communication device includes, in operation, a circuit that determines a first uplink (UL) band narrower than a second UL band associated with the communication device, and a transmitter that transmits a multi-PRACH transmission in the first UL band in operation.

Description

Technical Field

[0001] The following disclosure relates to a communication apparatus and a communication method for multi-Physical Random Access Channel (Multi-PRACH) transmission using a limited bandwidth, and more particularly, to a communication apparatus and a communication method for multi-PRACH transmission using a limited bandwidth over a multi-RACH Occasion (RO) in New Radio (NR).

Background Art

[0002] In the current Random Access Channel (RACH) procedure, a User Equipment (UE) receives a System Information Block 1 (SIB1) to derive a Physical Random Access Channel (PRACH) resource indicating a RACH occasion (RO) in time and frequency domain resources, as well as the mapping of Synchronization Signal / PBCH Block (SSB) to RO in terms of the number of SSBs per RO and the number of preambles R per RO. Thereafter, the UE selects one RO in the initial Uplink Bandwidth Part (UL BWP) and transmits a PRACH preamble (so-called Msg1 or PRACH transmission) called a single PRACH transmission. Referring to the typical 4-step random access procedure between the UE of illustration 600 in FIG. 6 and a base station or gNodeB (gNB), 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, a scheduled transmission is transmitted from the UE to the gNB. In step 608, the UE receives contention resolution for transmission from the gNB. The UE cannot select other PRACH preambles until the expiration of the RAR window for the same transmitted PRACH preamble.

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

[0004] Furthermore, Rel-17 NR supports Reduced Capability (RedCap) UEs with a reduced maximum BW (20 MHz in the case of FR1 and 100 MHz in the case of FR2). If the initial uplink (UL) bandwidth part (BWP) (e.g., the BWP for non-RedCap UEs) is wider than the maximum bandwidth (BW) of the RedCap UE, a separate initial UL BWP for the RedCap UE within the maximum BW of the RedCap UE (e.g., in illustration 1400 of FIG. 14, a separate UL BWP 1402 is set for the RedCap UE and a separate UL BWP 1404 is set for non-RedCap UEs) is always set during initial access. Within the separate initial UL BWP, an RO for the RedCap UE is set.

[0005] Furthermore, to investigate potential extensions in sub-band non-overlapping full duplex (SBFD) and dynamic / flexible time-division duplex (TDD), a new research item on cross-division duplex (XDD) was approved in RAN#94-e [RP-213591]. In NR, the slot / frame format includes downlink (DL) symbols (or slots), uplink (UL) symbols (or slots), and flexible (F) symbols (or slots), and there are limitations on DL / UL configurations to avoid UL / DL interference between gNBs and UEs. On the other hand, only the F symbols (or slots) can be further configured either semi-statically or dynamically as either DL symbols (or slots) or UL symbols (or slots). For example, referring to illustration 1500 in FIG. 15, in Releases 15 / 16 / 17, the F symbol (or slot) is configured as a UL symbol (or slot) (see 1504). In XDD, in the F symbol (or slot), some UEs can be further configured as DL and other UEs can be further configured as UL, so the bandwidths of multiple sub-bands (BW XDD ) can be configured in the time-domain F symbol (or slot). For example, as shown in illustration 1500 in FIG. 15, for UE#1 and UE#2, the frequency resource allocation per F symbol (or slot) is flexibly configured. Depending on the application, a large number of downlink receptions for UE#1 (see 1506) and few uplink transmissions for UE#2, or a large number of 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, while on the UE side, half-duplex communication can be used.

[0006] However, there has been little discussion so far about communication devices and methods for multi-PRACH transmission using limited bandwidth.

[0007] Therefore, there is a need for a communication device and method that provide a technical solution that is feasible for multi-PRACH transmission using a limited bandwidth across multiple ROs in NR. Further, other desirable features and characteristics will become apparent from the following detailed description and the appended claims, in conjunction with the accompanying drawings and the background of the present disclosure.

Prior Art Documents

Non-Patent Documents

[0008]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Non-Patent Document 5

Non-Patent Document 6

Non-Patent Document 7

Summary of the Invention

Problems to be Solved by the Invention

[0009] Non-limiting and exemplary embodiments facilitate providing a communication device and method for multi-PRACH transmission using a limited bandwidth.

Means for Solving the Problems

[0010] According to the first embodiment of the present disclosure, in operation, a communication device includes a circuit that determines a first uplink (UL) band that is narrower than a second UL band associated with the communication device, and a transmission unit that transmits a multi-PRACH transmission in the first UL band in operation.

[0011] According to the second embodiment of the present disclosure, in operation, a base station is provided that includes a circuit that generates information regarding first and second uplink (UL) bands, a transmission unit that transmits the information to a communication device in operation, and a reception unit that receives a multi-PRACH transmission from the communication device in operation.

[0012] According to the third embodiment of the present disclosure, a communication method is provided that includes determining a first UL band that is narrower than a second UL band associated with a communication device, and transmitting a multi-PRACH transmission in the first UL band.

[0013] Note that a general embodiment or a specific embodiment can be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any optional combination thereof.

[0014] Further benefits and advantages of the disclosed embodiments will become apparent from the present specification and the drawings. These benefits and / or advantages can be obtained individually by various embodiments and features of the present specification and the drawings, and it is not necessary to provide all embodiments and features for the purpose of obtaining one or more of such benefits and / or advantages.

Brief Description of the Drawings

[0015] The embodiments of the present disclosure are merely examples, and will be better understood and will become readily apparent to those skilled in the art from the following description in association with the drawings.

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Embodiments for Carrying Out the Invention

[0016] Those skilled in the art can understand that the elements in the figures are described simply and clearly and are not necessarily drawn to a certain scale. For example, in order to better understand this embodiment, the dimensions of some of the elements in the figures, block diagrams, or flowcharts may be exaggerated with respect to other elements.

[0017] Some embodiments of the present disclosure will be described by way of example with reference to the drawings. Like reference numerals and letters in the drawings refer to like or equivalent elements.

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

[0019] The protocol stack of the user plane of NR (see, for example, Section 4.4.1 of Non-Patent Document 2) includes a PDCP (Packet Data Convergence Protocol (see Section 6.4 of Non-Patent Document 2)) sublayer, an RLC (Radio Link Control (see Section 6.3 of Non-Patent Document 2)) sublayer, and a MAC (Medium Access Control (see Section 6.2 of Non-Patent Document 2)) sublayer that are terminated on the network side in the gNB. Also, a new sublayer of the access stratum (AS: Service Data Adaptation Protocol) (SDAP) is introduced above the PDCP (see, for example, Section 6.5 of Non-Patent Document 2). Also, a protocol stack for the control plane is defined for NR (see, for example, Section 4.4.2 of Non-Patent Document 2). An overview of the layer 2 functions is described 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 Non-Patent Document 2. Further, sidelink communication is introduced in Non-Patent Document 2. The sidelink supports direct communication between UEs using a sidelink resource allocation mode, physical layer signals / physical layer channels, and physical layer procedures (see, for example, Section 5.7 of Non-Patent Document 2).

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

[0021] For example, the physical layer (PHY) is responsible for functions such as encoding, PHY HARQ processing, modulation, multi-antenna processing, and mapping of signals to appropriate physical time-frequency resources. Also, the physical layer handles the mapping of transport channels to physical channels. The physical layer provides services to the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for the transmission of a specific transport channel, and each transport channel is mapped to a corresponding physical channel. For example, physical channels include 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, as well as PBCH (Physical Broadcast Channel). Furthermore, physical sidelink channels include Physical Sidelink Control Channel (PSCCH), Physical Sidelink Shared Channel (PSSCH), Physical Sidelink Feedback Channel (PSFCH), and Physical Sidelink Broadcast Channel (PSBCH).

[0022] The use cases / deployment scenarios of NR 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 the downlink and 10 Gbps in the uplink) and effective (user-experienced) data rates about three times those provided by IMT-Advanced. On the other hand, for URLLC, more stringent requirements are imposed for ultra-low latency (0.5 ms for each of UL and DL for user plane latency) and high reliability (1 - 10 -5 ) within 1 ms. Finally, for mMTC, a high connection density (1,000,000 devices / km in urban environments 2 ), wide coverage in harsh environments, and extremely long-lived batteries (15 years) for low-cost devices may be required.

[0023] Therefore, the new numerology of OFDM (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 effective for other use cases. For example, in a low-latency service, preferably, the symbol length is shorter (and thus the subcarrier spacing is larger) and / or the number of symbols per scheduling interval (also referred to as TTI) is smaller than that of mMTC services. Further, in a deployment scenario with a large channel delay spread, preferably, the CP length is longer than that in a scenario with a short delay spread. The subcarrier spacing should be optimized according to the situation so that a similar CP overhead is maintained. The value of the subcarrier spacing supported by NR can be one or more. Therefore, currently, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz... are considered. Symbol length T u and subcarrier spacing Δf are directly related by the formula Δf = 1 / T u Similar to the LTE system, the term "resource element" can be used to mean the smallest resource unit set from one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0024] In the new radio system 5G-NR, for each numerology and each carrier, a resource grid of subcarriers and OFDM symbols is defined for each of the uplink and downlink. Each element of the resource grid is called a resource element and is specified based on the frequency index in the frequency domain and the symbol position in the time domain (see Non-Patent Document 2).

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

[0026] In particular, gNB and ng-eNB host the following main functions: - Functions of radio resource management such as radio bearer control, radio admission control, connection mobility control, and dynamic allocation (scheduling) of resources to the UE in both the uplink and downlink; - IP header compression, encryption, and integrity protection of data; - Selection of the AMF at the time of UE attachment when it is not possible to determine the routing to the AMF from the information provided by the UE; - Routing of user plane data towards the UPF; - Routing of control plane information towards the AMF; - Setup and release of connections; - Scheduling and transmission of paging messages; - Scheduling and transmission of system information messages (with the AMF or the operation, administration, and maintenance function (OAM) as the source); - Configuration of 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 the RRC_INACTIVE state; - Delivery function for non-access stratum (NAS) messages; - Sharing of the radio access network; - Dual connectivity; - Tight cooperation between NR and E-UTRA.

[0027] The Access and Mobility Management Function (AMF) hosts the following main functions: - Function to terminate non-access stratum (NAS) signaling; - Security of NAS signaling; - Access Stratum (AS) security control; - Core Network (CN) node - to - node signaling for mobility between 3GPP access networks; - Reachability of idle - mode UEs (including control and execution of paging re - transmission); - Management of registration areas; - Support for in - system mobility and inter - system mobility; - Access authentication; - Access authorization including roaming rights check; - Mobility management control (subscription and policy); - Support for network slicing; - Selection of Session Management Function (SMF).

[0028] Furthermore, the User Plane Function (UPF) hosts the following main functions: - Anchor point for intra - RAT mobility / inter - RAT mobility (where applicable); - External PDU (Protocol Data Unit) session point for interconnection with data networks; - Packet routing and forwarding; - Packet inspection and enforcement of policy rules for the user plane part; - Reporting of traffic usage; - An uplink classifier that supports routing of traffic flows to a data network; - A Branching Point for supporting a multi-homed PDU session; - QoS processing for the user plane (e.g., packet filtering, gating, UL / DL rate enforcement); - Verification of uplink traffic (mapping to QoS flows of SDFs); - Buffer management of downlink packets and trigger function for downlink data notification.

[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 UPFs; - A traffic steering setting function in the User Plane Function (UPF) for routing traffic to appropriate destinations; - Policy enforcement and QoS for the control plane; - Notification of downlink data.

[0030] 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 2). The transition steps are as follows.

[0031] 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: The scenario where the gNB rejects the request is described below.) 3. The first NAS message from the UE sent in piggyback mode in RRCSetupComplete is sent to the AMF.) 4 / 4a / 5 / 5a. Additional NAS messages can be exchanged between the UE and the AMF. See Reference

[22] in Non-Patent Document 3 (3GPP TS 23.122: "Non-Access Stratum (NAS) functions related to mobile stations in idle mode"). 6. The AMF prepares UE context data (including PDU session context, security keys, UE radio capabilities, and UE security capabilities, etc.) and sends it to the gNB.) 7 / 7a. The gNB activates AS security with the UE.) 8 / 8a. The gNB executes a reconfiguration to set up SRB2 and DRBs.) 9. The gNB notifies the AMF that the setup procedure has been completed.)

[0032] RRC is the upper layer signaling (protocol) used for the configuration of the UE and 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 together with an INITIAL CONTEXT SETUP REQUEST. Then, the gNB activates AS security together with the UE. This is done by the gNB sending a SecurityModeCommand message to the UE and the UE responding to the gNB with a SecurityModeComplete message. Thereafter, the gNB sends an RRCReconfiguration message to the UE, and upon receiving the RRCReconfigurationComplete from the UE in response, performs a reconfiguration for setting up Signaling Radio Bearer 2 (SRB2) and Data Radio Bearer (DRB). For signaling-only connections, since SRB2 and DRB are not set up, the steps regarding RRCReconfiguration are skipped. Finally, the gNB notifies the AMF in an INITIAL CONTEXT SETUP RESPONSE that the setup procedure is complete.

[0033] Figure 4 shows some of the use cases for 5G NR. In the 3rd generation partnership project new radio (3GPP NR), three use cases that were envisioned by IMT-2020 to support a wide variety of services and applications are being considered. The formulation of the first-phase specifications for enhanced mobile-broadband (eMBB) has been completed. Current and future work includes, in addition to expanding the support for eMBB, standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC). Figure 4 shows some examples of the envisioned usage scenarios of IMT after 2020 (see, for example, FIG. 2 of Non-Patent Document 4).

[0034] The use cases for URLLC have strict requirements for performance such as throughput, latency (delay), and availability. The use cases for URLLC are envisioned as one of the kind that enables future applications such as wireless control of industrial production processes or manufacturing processes, remote medical surgery, automation of power transmission and distribution in smart grids, and traffic safety. The ultra-high reliability of URLLC is supported by identifying technologies that meet the requirements set by Non-Patent Document 5. In NR URLLC in Release 15, as an important requirement, it is included that the target user plane latency is 0.5 ms in UL (uplink) and 0.5 ms in DL (downlink). The general requirement for a single packet transmission in URLLC is that when the user plane latency is 1 ms, the block error rate (BLER) is 1E-5 for a packet size of 32 bytes.

[0035] From a physical layer perspective, reliability can be improved in many ways. Current opportunities for improving reliability include defining a separate CQI table for URLLC, a more compact DCI format, PDCCH repetition, etc. However, this opportunity can expand for achieving ultra-high reliability as NR becomes more stable and more developed (with respect to the important requirements of NR URLLC). Specific use cases of NR URLLC in Release 15 include extended reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0036] Also, the technology extensions targeted by NR URLLC aim to improve latency and reliability. Technology extensions for improving latency include configurable numerology, mini-slot-based scheduling with flexible mapping, grant-free uplink (for set grants), repetition at the mini-slot level in the data channel, and pre-emption in the downlink. Pre-emption means that a transmission for which resources have already been allocated is stopped, and the already allocated resources are used for another transmission with a lower latency / higher priority requirement requested later. Thus, an already permitted transmission is replaced 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 replaced by a transmission of service type B (eMBB, etc.). Technology extensions for improving reliability include a dedicated CQI / MCS table for a target BLER of 1E-5.

[0037] The characteristics of the use cases of mMTC (massive machine type communication) typically lie in the extremely large number of connected devices that transmit relatively small amounts of data and are typically less affected by latency. The devices are required to be low-cost and have a very long battery life. From the perspective of NR, using a very narrow bandwidth portion is one solution that can save power from the UE's perspective and enable a longer battery life.

[0038] As described above, it is predicted that the scope of reliability improvement in NR will become broader. High reliability or ultra-high reliability is one of the important requirements for all cases, especially those necessary for URLLC and mMTC. Several mechanisms can improve reliability from both the wireless and network perspectives. Generally, there are two to three important areas that may contribute to reliability improvement. These areas include compact control channel information, repetition of data channels / control channels, and diversity in the frequency domain, time domain, and / or spatial domain. These areas are generally applicable to reliability improvement regardless of the specific communication scenario.

[0039] Regarding NR URLLC, further use cases with more stringent requirements are envisioned, such as factory automation, transportation, and power distribution. The stringent requirements include high reliability (reliability up to the 10 -6 level), high availability, a packet size of up to 256 bytes, time synchronization up to about several μs (depending on the use case, the value can be set to 1 μs or several μs according to the frequency range and a short latency of about 0.5 ms to 1 ms, especially a latency of 0.5 ms in the targeted user plane).

[0040] Furthermore, for NR URLLC, there can be several technical enhancements from the perspective of the physical layer. These technical enhancements include the extension of the Physical Downlink Control Channel (PDCCH) related to compact DCI, the repetition of PDCCH, and the increase in PDCCH monitoring. Also, the extension of UCI (Uplink Control Information) is related to the extension of enhanced HARQ (Hybrid Automatic Repeat Request) and CSI feedback. There can also be enhancements to PUSCH related to mini-slot level hopping, and enhancements to retransmission / repetition. The term "mini-slot" refers to a Transmission Time Interval (TTI) that contains fewer symbols than a slot (a slot has 14 symbols).

[0041] The 5G Quality of Service (QoS) model is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (Guaranteed 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, a QoS flow is the finest-grained QoS differentiation in a PDU session. A QoS flow is identified within a PDU session by a QoS Flow ID (QFI: QoS Flow ID) that is carried in an encapsulation header via the NG-U interface.

[0042] For each UE, the 5GC establishes one or more PDU sessions. For each UE, in accordance with the PDU session, the NG-RAN establishes at least one Data Radio Bearer (DRB) as shown above with reference to, for example, Figure 3. Also, additional DRBs for the QoS flows of that PDU session can be set later (it depends on the NG-RAN when to set them). The NG-RAN maps packets belonging to various PDU sessions to various DRBs. While NAS-level packet filters in the UE and 5GC associate UL packets and DL packets with QoS flows, AS-level mapping rules in the UE and NG-RAN associate UL QoS flows and DL QoS flows with DRBs.

[0043] Figure 5 shows the 5G NR non-roaming reference architecture (see Section 4.2.1.1 of Non-Patent Document 6). The Application Function (AF) (for example, the external application server that hosts 5G services illustrated in Figure 4) communicates with the 3GPP core network to support providing services, for example, influencing the routing of traffic by the application, accessing the Network Exposure Function (NEF), or interacting with the policy framework for policy control (for example, QoS control) (see Policy Control Function (PCF)). Based on operator deployment, Application Functions considered to be trusted by the operator can communicate directly with the relevant Network Functions. Application Functions not permitted by the operator to directly access Network Functions communicate with the relevant Network Functions using the external exposure framework via the NEF.

[0044] FIG. 5 further shows 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 5GC, as well as V2X Application Server (V2AS) and Data Network (DN; e.g., operator services, Internet access, or third-party services). All or part of the core network functions and application services may be deployed and operate in a cloud computing environment.

[0045] The problem to be solved in the present disclosure is that it has not yet been specified how multi-PRACH transmission for UEs with different BW capabilities should be performed.

[0046] In Embodiment E1, for the UE, an allocation with fewer frequency resources per RO for multi-PRACH transmission, or an allocation with fewer frequency resources for all ROs, is set according to one of the following conditions. - The bandwidth of the serving cell is divided into a plurality of sub-bands (BW XDD ) that is narrower than a threshold (e.g., for a UE operating in SBFD / XDD as shown in illustration 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, in the case of a RedCap UE as shown in illustration 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, an RO for the RedCap UE is determined).

[0047] The threshold may be the set initial UL BWP. Further, the set initial BWP can be replaced by a set of resource blocks (RB), a set of sub-bands into which the serving cell band is divided, the total bandwidth of the RO frequency division multiplexed (FDMed) in a current set temporary instance by the upper layer parameter msg1-FDM, or other values set by the gNB. Advantageously, the solution proposed according to embodiment E1 improves the coverage performance of UEs with different BW capabilities. It will be understood that the UL BWP and the UL bandwidth can be used interchangeably.

[0048] In the example of FIG. 16, the frequency resource allocation with fewer ROs is contained within the BW in the time domain. XDD For example, the frequency resource allocation with fewer ROs per RO is determined based on a function of the BW in the time domain. XDD This function can be expressed as FperRO XDD = FperRO nonXDD × BW XDD / iBWP nonXDD where FperRO nonXDD is the bandwidth of the RO for non-XDD UEs, and iBWP nonXDD is the set initial UL BWP for non-XDD UEs. Referring to FIG. 16, iBWP nonXDD 1602 generally has a larger BW than BW XDD 1604. This is applicable when the time domain resources include semi-static flexible symbols / flexible slots. For simplicity, for a set of consecutive flexible slots and / or uplink slots, the BW XDDThe same value can be applied.

[0049] Alternatively, in XDD, as shown on the right of FIG. 16, there are two or more bandwidths in the UL band. For example, the first UL band of BW_XDD (i.e., in the second time symbol / time slot) is narrower than the second UL band (i.e., in the third time symbol / time slot). In this case, all frequency resources with fewer ROs are allocated to the first UL band (second time symbol / time slot), and all frequency resources with more ROs are allocated to the second UL band (third time symbol / time slot).

[0050] If the initial UL BWP of the non-RedCap UE is wider than the maximum BW of the RedCap UE, during initial access, a separate initial UL BWP for the RedCap UE within the maximum BW is set. ROs for RedCap are determined within a 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 frequency resource allocation with fewer ROs for all ROs is contained within a different initial UL BWP. This is FperRO RedCap =FperRO nonRedCap ×(siBWP RedCap ) / (iBWP nonRedCap ) and can be expressed as, where FperRO RedCap and FperRO nonRedCap are the bandwidths of the ROs for the RedCap UE and the non-RedCap UE at a time instance, respectively, siBWP RedCap is the separate initial UL BWP for the RedCap UE, and iBWP RedCap is the initial UL BWP for the non-RedCap UE. The subcarrier offset SubcarrierOffset_CE(i,j) of the RedCap UE RedCap can be set individually, and the subcarrier offset SubcarrierOffset_CE(i,j) of the non-RedCap UE nonRedCapIt can also be implicitly derived from. The SSB-to-RO mapping of the RedCap UE is the same as that of non-RedCap UEs. For example, referring to FIG. 17, the separate initial UL BWP 1702 for the RedCap UE has a smaller frequency resource allocation than the initial UL BWP 1704 for non-RedCap UEs, but for both BWPs, the SSB-to-RO mapping is the same 1 / 2.

[0051] Therefore, when the initial UL BWP for non-RedCap UEs is below the maximum BW of the RedCap UE, either Embodiment E2 or Embodiment E3 described in the following paragraphs can be used to determine the RO for multi-PRACH transmission for the RedCap UE in the same way as for non-RedCap UEs. When the initial UL BWP for non-RedCap UEs is wider than the maximum BW of the RedCap UE, Embodiment E1 can be used to determine the RO for multi-PRACH transmission of the RedCap UE in a separate initial UL BWP, but for determining the RO for multi-PRACH transmission of non-RedCap UEs in the initial UL BWP E1, either Embodiment E2 or Embodiment E3 is used.

[0052] Also, in a variant of Embodiment E1, different SSB-to-RO mappings are proposed for the UE. For example, referring to the illustration 1800 in FIG. 18, in the initial UL BWP 1802 of the RedCap UE or the small uplink band of the XDD UE, the SSB-to-RO mapping 1806 is 1 (e.g., each SSB is mapped to one RO), while in the initial UL BWP 1804 of the non-RedCap UE or the large uplink band of the XDD UE (e.g., legacy UE or normal Release 15 / 16 / 17 UE), the SSB-to-RO mapping 1808 is 1 / 2 (e.g., each SSB is mapped to two ROs).

[0053] Alternatively, more time regions RO are proposed to the UE. Referring to illustration 1900 in FIG. 19A, the multi-PRACH transmission is performed by the RedCap UE at time instances t_0 (refer to 1902) and t_1 (refer to 1904), and is performed by the non-RedCap UE at time instance t_0 (refer to 1906). This provides more processing time for the transmission of the RedCap UE, which is advantageous because the RedCap UE has limited capabilities compared to the non-RedCap UE. Also, thereby, the RedCap UE can change the coarse direction in the time domain using hybrid beamforming or analog beamforming, thereby forming a finer beam within the coarse direction in the frequency domain to transmit the preamble (for example, the first coarse direction includes the SSB#0 beam and the SSB#1 beam at t_0, and the second coarse direction includes the SSB#2 and SSB#3 beams at t_1). Thereby, better reception at the gNB can be provided.

[0054] Furthermore, in another modification of Embodiment E1, the number of ROs at each time instance (e.g., symbols / slots at t_0 and t_1 as described above, or the second time symbol / time slot and the third time symbol / time slot as described above) can be set to different values. For example, referring to illustration 1908 in FIG. 19B, due to the threshold, all ROs do not fit within the bandwidth of a plurality of sub-band BWs XDD or within the bandwidth of a separate initial UL BWP for the RedCap UE. A subset of ROs (such as RO#0, RO#1, RO#2, RO#s3, and RO#4 as shown in RO subset 1910) that fit within the bandwidth of a plurality of sub-band BWs XDD or within the separate initial UL BWP for the RedCap UE are transmitted at t_0. On the other hand, the remaining ROs (such as RO#5, RO#6, and RO#7 etc. as shown in RO subset 1912) are transmitted at t_1 1916.

[0055] Alternatively, in one time symbol / time slot, the number of ROs in the small UL (sub)band in XDD may be at least small, and in one time symbol / time slot, the number of ROs in the large UL (sub)band in XDD may be at most large. As an example, ROs may be allocated 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) fits within the small UL (sub)band with a small bandwidth and is transmitted at t_0 1914 in the small UL (sub)band in XDD. On the other hand, 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.

[0056] Also, the SSB-to-RO mapping may be the same or different between the small UL (sub)band and the large UL (sub)band. Alternatively, the SSB-to-RO mapping of the small UL (sub)band may be the same as the SSB-to-RO mapping of a part of the large UL (sub)band. The said part of the large UL band may be at the same frequency as the small UL (sub)band. The SSB-to-RO mapping of other parts of the large UL (sub)band may be omitted (dropped) and may not be defined in the small UL (sub)band.

[0057] Another problem addressed by the present disclosure is that there is no specification on how to perform multi-PRACH transmission over multiple ROs in NR. When a UE attempts to perform single-PRACH transmission (legacy UE function) within one slot or multi-PRACH transmission (Rel.18 UE function) over multiple slots by attempting multiple ROs based on the same PRACH resource, the gNB does not recognize the multi-PRACH transmission from the UE, so the PRACH detection performance is not a desirable performance.

[0058] In actual operation, it is expected that the performance of the UL channel will be difficult in most scenarios. Also, for example, there are emerging vertical use cases that require a lot of traffic for UL such as video upload or camera monitoring. From the perspective of coverage performance, it has been identified by research that PRACH is one of the bottleneck channels. However, since the scope of the coverage enhancement (CovEnh) in Rel.17 is limited, the 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 purposes is to - achieve multiple PRACH transmissions using the same beam in the 4-step RACH procedure, and - study PRACH transmissions using different beams in the 4-step RACH procedure and, if justified, specify the specifications, which is the specification of the PRACH coverage enhancement (RAN1, RAN2) [RP-213579].

[0059] The extension of PRACH targets Frequency Range 2 (FR2) and can also be applied to FR1 if applicable to FR1. Furthermore, the extension of PRACH targets short PRACH formats and is also applicable to other formats if applicable to other formats.

[0060] A prior art solution based on PRACH detection defined in Non-Patent Document 7 in the current NR for this problem is shown in Illustration 700 of FIG. 7. When multiple PRACH transmissions are performed by a UE (e.g., to achieve selective gain in the time domain), the gNB attempts to detect the PRACH preamble multiple times (e.g., as shown in the trials from the first trial 702 to the m-th trial 704 of PRACH detection) from the multi-PRACH transmission in the time domain without knowing about the multi-PRACH transmission. From the perspective of the gNB, there is no difference between the PRACH resources of single PRACH transmission or multi-PRACH transmission in this solution means. The selective gain is smaller compared to the case with dedicated multi-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 resources corresponding to the n-th transmission are used. Note that coherent accumulation requires high gNB complexity.

[0061] According to the solution proposed in the present disclosure to address the above problem, the UE performs multiple PRACH transmissions based on control information regarding a multi-PRACH transmission pattern (Embodiment E2) or a RACH occasion (RO) of multi-PRACH transmission (Embodiment E3). The multi-PRACH transmission pattern or the RO of multi-PRACH transmission may vary for each CE level. When the RO of multi-PRACH transmission is associated by control information, the multi-PRACH transmission can be implicitly determined from the RO. To ensure energy accumulation, the PRACH detection of the gNB that provides low complexity and reasonable detection gain can be utilized. Coherent accumulation may also be used when the UE transmission is specified as a plurality of coherent PRACH transmissions. By setting multiple CE levels, the noise level can be distinguished according to the requirements of the number of PRACH transmission times. Compared with the above-mentioned prior art solutions, the proposed solution advantageously realizes better performance improvement in coverage.

[0062] In Embodiment E2, the UE receives a multi-PRACH transmission pattern (K≥1 slots) for each CE level in order to determine the RACH occasion (RO) of each PRACH transmission of a plurality of PRACH transmissions (e.g., multi-PRACH transmission) according to the CE level. The multi-PRACH transmission patterns for each CE level may be different from each other. For example, the RO for transmission included in the multi-PRACH transmission pattern for a lower CE level (e.g., CE level 1) may be less than that for the multi-PRACH transmission pattern for a higher CE level (e.g., CE level 2). For the examples shown in FIGS. 800 and 812 of FIGS. 8A and 8B, l 0 =0 (as will be further described in a later paragraph, the formula l i =l 0 +iN dur RA of l 0 etc.) and an A3 preamble of length 6 symbols are used, with K = 2 slots for CE level 1 (see reference numeral 814) and K = 3 slots for CE level 2 (see reference numeral 816).

[0063] Due to the overlap with the slot boundary (e.g., the boundary of two slots as shown by reference numerals 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 is advantageous for the purpose of interaction by frequency hopping (FH) based on the slot level, or may be advantageous if the UE is set by the gNB to receive a power control command at the start of the slot, or is advantageous in a flexible case where the UE is set by the gNB to monitor and / or receive the PDCCH in the symbol at the start of the slot.

[0064] Instead of using the term "multi-PRACH transmission for each CE level", it should be understood that there can be multi-PRACH transmission for each number of repetitions of PRACH transmission, for each one or more reference signal received power (RSRP) thresholds (e.g., thresholds such as RSRP threshold 1 818 and RSRP threshold 2 820), or for other criteria that can be set by the associated gNB.

[0065] Also, according to a modification of Embodiment E2, based on K slots, the UE can be set such that the UE derives the RO for each of a plurality of PRACH transmissions including the PRACH length of symbol unit N (i.e., the duration length of each of a plurality of PRACH transmissions according to the PRACH preamble format) and the start position. The start position may be based on any of the following alternatives. dur RA In Alternative 1.1, the start position of RO- for each of the plurality of PRACH transmissions is derived, for example, as shown in FIG. 8A, by fitting the plurality of PRACH transmissions within K slots. As defined in Non-Patent Document 1

[0066]

Number

Number

[0067] In alternative 1.2, in the first of the K slots, the start positions of the ROs of a subset of the plurality of PRACH transmissions are derived by fitting these ROs within the first slot. These start positions of the ROs are repeated in the remaining (K - 1) slots, as shown in illustration 900 of FIG. 9. In the first slot 902 of the K slots, together with K = 2 slots for CE level 1 and K = 3 slots for CE level 2, l consisting of 6 symbols 0 = 0 and the A3 preamble, and two PRACH transmissions 904 and 906 are defined, and these transmissions are repeated in the subsequent (K - 1) slots. In this case,

Number

[0068] In a variant of further embodiment E2, within the K slots, one or more smaller sub-patterns can be determined based on one or more of the following. First, in alternative 2.1, in the collision handling of the derived ROs of one or more PRACH transmissions overlapping with slot boundaries and / or signals (or channels) of different priorities, the UE can drop only the one or more overlapping PRACH transmissions and keep the remaining PRACH transmissions to be transmitted. Signals (or channels) with different priorities can refer to downlink reception or uplink transmission with higher priority (e.g., reception of SSB or reception of PDCCH for URLLC services). Within the 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 FIG. 800 of FIG. 8A). Advantageously, this is beneficial for the purpose of interaction with frequency hopping (FH) based on the slot level, i.e., the multi-PRACH transmission pattern can include multiple FH hops and, for frequency selective gain, coherent PRACH detection can be performed for each FH hop.

[0069] In another alternative 2.2, for the collision handling of the derived ROs of one or more PRACH transmissions with slot boundaries and / or signals (or channels) of different priorities, the UE can generate a PRACH preamble for each of the one or more PRACH transmissions and transmit all the PRACH transmissions of the multiple PRACH transmissions. An example of using both alternatives 1.1 and 2.2 is shown in embodiment 1000 of FIG. 10 for collision handling at the slot boundary. For example, referring to FIG. 1000, l 0=0 and a 6-symbol A3 preamble of length are 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 for PRACH transmission within K slots and obtain a higher gain in detection. Second, the maximum duration of UE capabilities is utilized to maintain phase continuity and power consistency.

[0070] In Embodiment E3, the UE may be configured to receive a notification indicating ROs in a plurality of PRACH transmissions. Upon receiving the notification, the UE determines a plurality of ROs for multi-PRACH transmission based on the conventional procedure. In this case, the multi-PRACH transmission pattern is implicitly determined from the notified ROs.

[0071] There can be various ways for signaling for notifications. In Option 1, the notification can be done by upper layer parameters in the Master Information Block (MIB) and / or System Information Block (SIB). FIG. 11A shows an illustration 1100 of upper layer parameters indicating an RO for multi-PRACH transmission according to Embodiment E3. This is an example of upper layer parameters for notifying an RO for multi-PRACH transmission (see 1102), the 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 can be used, and the current table for random access configuration is extended by adding a new entry for notifying an RO for multi-PRACH transmission. The extended table can be set as shown in Table 1110 of FIG. 11B or can be pre-configured. Table 1110 is an example of Table 6.3.3.2-3 of Non-Patent Document 1 (random access configuration for Frequency Range 1 (FR1) and asymmetric spectrum) extended to notify an RO for multi-PRACH transmission (see portion 1112 of the table). In Table 1110, the current upper layer parameter prach-ConfiguationIndex is reused to indicate the rows of the table. The UE determines the duration N dur RA of the PRACH and the start position of each of the plurality of ROs by legacy procedures. It will be understood that Options 1 and 2 can also be used in combination to indicate the ROs for multiple PRACH transmissions.

[0072] It is also possible to implement general modifications for Embodiments E1 and E2, and the dedicated PRACH resources for multi-PRACH transmission set based on the CE level include dedicated radio resources and / or PRACH preambles. As an example, illustration 1200 in FIG. 12 shows the splitting of preambles for two CE levels. Individual R1 and R2 preambles (reference numerals 1202 and 1204 respectively) are set for each RO for CE levels 1 and 2. The UE can use the same frequency resource allocation to transmit any one of the R1 preambles or any one of the R2 preambles. In another example, in illustration 1300 of FIG. 13, for different CE levels for each RO, a split in the FDM (Frequency Division Multiplexed) scheme is performed, showing that subcarrier offsets are set 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 set to use subcarrier offset 1302 for CE level 1 and subcarrier offset 1304 for CE level 2.

[0073] Also, in any of Embodiments E1 to E3, in the case of the multi-PRACH transmission pattern, the UE can be set to continuously maintain power consistency and phase continuity for asynchronous detection of the PRACH. Further, the UE can be set to perform multiple PRACH transmissions by using the same beam, which is called PRACH repetition. PRACH repetition can be performed using the following alternative power ramping steps. In the first alternative, the PRACH repetition is started only after the UE reaches the maximum transmission power. When at the maximum transmission power, the UE increases (configurable) the number of PRACH transmissions to be sent. 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, the PRACH repetition is started before the UE reaches the maximum transmission power. For example, the UE increases the configurable number of PRACH transmissions at transmission power p i . In case of failure, the UE transmits the PRACH multiple times with the power ramping step p i = p i +Δ (where Δ is configurable). If the transmission power reaches the maximum value and there is still no response from the gNB, the process fails.

[0074] In all embodiments, during the multi-PRACH transmission pattern, the UE can be set to perform multi-PRACH transmission by using various 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 the multi-PRACH transmission pattern. Subsequently, the associated gNB performs only power addition during the PRACH transmission, and the gNB notifies in Msg2 the best narrow Tx beam index to be used by the UE in the subsequent steps of the PRACH procedure, i.e., Msg3 transmission.

[0075] In all embodiments, the multi-PRACH transmission pattern also means a multi-PRACH transmission window / multi-PRACH transmission time / multi-PRACH transmission period.

[0076] In all embodiments, a combination of preamble formats (e.g., formats A and B) can be used within the multi-PRACH transmission pattern to utilize time-domain resources.

[0077] Also, in any of the embodiments, energy accumulation addition can be performed at the gNB. In this case, the UE does not need to have coherent multiple PRACH transmissions.

[0078] FIG. 20A shows, according to Embodiment E2, an example flowchart for UE operation with a multi-PRACH transmission pattern set. In step 2002, for each CE level, a multi-PRACH transmission pattern (K≥1 slots) is set for the UE. In step 2004, the UE derives a RACH occasion (RO) for the multi-PRACH transmission pattern of the CE level that depends on the RSRP threshold. In step 2006, it is determined whether one or more PRACH transmission ROs overlap with the 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 executes all of the remaining PRACH transmissions or the multi-PRACH transmissions.

[0079] Figure 20B shows a flowchart of UE operation in Embodiment E3. In step 2016, the UE receives a notification indicating an RO for each PRACH transmission of a plurality of PRACH transmissions (e.g., multi-PRACH transmission). In step 2018, the UE determines a plurality of ROs for multi-PRACH transmission for each CE level. Each CE level depends on an RSRP threshold based on legacy procedures. In step 2020, the UE transmits a plurality of PRACH transmissions based on the determined plurality of ROs.

[0080] Figure 20C shows flowchart 2022 for RedCap UE operation according to Embodiment E1. It is a general flowchart for a RedCap UE that can access a serving cell according to an initial UL BWP set for a non-RedCap UE by a gNB. In step 2024, the gNB sets an 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, and a two-step method is used to determine an RO for multi-PRACH transmission for the RedCap UE. In step 1, either Embodiment E2 or Embodiment E3 is implemented to formulate an RO for multi-PRACH transmission for the non-RedCap UE. In step 2, for the RedCap UE, an allocation with fewer frequency resources per RO than for the non-RedCap UE is set in a separate initial UL BWP. On the other hand, if it is determined in step 2026 that the case where the initial UL BWP is wider than the maximum BW of the RedCap UE does not apply, the process proceeds to step 2028, and either Embodiment E2 or Embodiment E3 is used to determine an RO for multi-PRACH transmission for the RedCap UE and the non-RedCap UE within a shared initial UL BWP. From either step 2028 or step 2030, the process proceeds to step 2032, and the RedCap UE transmits multiple PRACH transmissions in the shared initial UL BWP (from step 2028) or in a separate UL BWP (from step 2030).

[0081] Figure 21 shows flowchart 2100 showing a communication method according to various embodiments. In step 2102, a first UL band narrower than a second uplink (UL) band is associated with a communication device. In step 2104, multi-PRACH transmission is transmitted in the first UL band.

[0082] FIG. 22 shows a partial schematic view of a communication device 2200 that can be implemented by various embodiments and examples shown in FIGS. 1 to 21. The communication device 2200 can be implemented as a UE according to various embodiments.

[0083] The various functions and operations of the communication device 2200 are arranged in each layer according to a hierarchical model. In this model, the lower layer reports to the upper layer according to the 3GPP specifications and receives commands from the upper layer. For simplicity, the details of the hierarchical model are not described in this disclosure.

[0084] As shown in FIG. 22, the communication device 2200 may include a circuit 2214, at least one wireless transmission unit 2202, at least one wireless reception unit 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 control unit 2206. The control unit 2206 is used to execute tasks designed to be executed by at least one control unit 2206 with the assistance of software and hardware. The tasks include controlling communication with one or more other communication devices within a wireless network. The circuit 2214 may further include at least one transmission signal generation unit 2208 and at least one reception signal processing unit 2210. The at least one control unit 2206 controls at least one transmission signal generation unit 2208 for generating signals (e.g., signals indicating a geographic area) to be transmitted to one or more other communication devices via at least one wireless transmission unit 2202, and at least one reception signal processing unit 2210 for processing signals (e.g., signals indicating a geographic area) received from one or more other communication devices via at least one wireless reception unit 2204 under the control of at least one control unit 1506. The at least one transmission signal generation unit 2208 and the at least one reception signal processing unit 2210 may be stand-alone modules of the communication device 2200 that communicate with at least one control unit 2206 for the above-described functions, as shown in FIG. 22. Alternatively, the at least one transmission signal generation 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 apparent to those skilled in the art that the arrangement of these functional modules is flexible and may vary according to actual needs and / or requirements. Data processing, virtual memory, and other related control devices can be provided on a suitable circuit board and / or within a chipset. In various embodiments, during operation, the at least one wireless transmission unit 2202, the at least one wireless reception unit 2204, and the at least one antenna 2212 may be controlled by at least one control unit 1506.

[0085] The communication device 2200 provides functions required for a plurality of multi-PRACH transmissions with limited bandwidth during operation. For example, the communication device 2200 may be a UE, and the circuit 2214 may determine a first uplink (UL) band associated with the communication device during operation, and the first UL band is narrower than the second UL band. The wireless transmission unit 2202 may transmit multi-PRACH transmissions in the first UL band during operation.

[0086] The first UL band may be narrower than a threshold value, the second UL band may be equal to or wider than the threshold value, and the threshold value may be an initial uplink bandwidth part (BWP), or a resource block (RB) set, or a subset of a plurality of subbands into which a serving cell band is divided, or the entire bandwidth of a RACH occasion (RO) frequency-division multiplexed (FDM) at one time instance.

[0087] The circuit 2214 may be further configured to determine a RACH occasion (RO) including the duration and start position for each PRACH transmission of the multi-PRACH transmissions within one or more transmission slots, and the wireless transmission unit 2202 may be further configured to transmit multi-PRACH transmissions based on the determined RO. The wireless transmission unit 2202 may be further configured to transmit multi-PRACH transmissions with fewer frequency resources per RO than the frequency resources of the second UL band in the first UL band. The wireless transmission unit 2202 may be further configured to perform multi-PRACH transmissions in a state where the frequency allocation of all ROs in the first UL band is within a subset of a plurality of subbands (BW XDD ) of the serving cell in the time domain.

[0088] The wireless transmission unit 2202 may be further configured to transmit multi-PRACH transmissions based on an SSB-to-RO mapping that is different from the SSB-to-RO mapping in the second UL band in the first UL band. The wireless transmission unit 2202 may be further configured to transmit multi-PRACH transmissions in a plurality of time symbols or time slots in the first UL band.

[0089] The wireless transmission unit 2202 may be further configured to transmit multi-PRACH transmissions in the first UL band at a first time instance and in the second UL band at a second time instance, and the number of available ROs configured at the first time instance used for the multi-PRACH transmission is different from the number of available ROs configured at the second time instance. The SSB-to-RO mapping of the first time instance used for the multi-PRACH transmission may be the same as or different from the SSB-to-RO mapping of the second time instance.

[0090] The wireless transmission unit 2202 may be further configured to transmit multi-PRACH transmissions with a reduced frequency resource allocation per RO in the first UL band when the maximum UL band associated with the communication device is narrower than a threshold. The wireless transmission unit 2202 may be further configured to transmit multi-PRACH transmissions in the first UL band in a plurality of time symbols or time slots. The wireless transmission unit 2202 may be further configured to transmit multi-PRACH transmissions such that the number of ROs used for transmission in each of the plurality of time slots is different from each other.

[0091] The wireless reception unit 2204 may receive control information regarding multi-PRACH transmissions during operation, and the wireless transmission unit 2202 may be further configured to transmit multi-PRACH transmissions based on the control information, and the multi-PRACH transmission includes a plurality of PRACH transmissions.

[0092] For example, the communication device 2200 may be a base station, and the circuit 2214 may generate information regarding the first and second UL bands during operation. The wireless transmission unit 2202 may transmit information to the communication device during operation. The wireless reception unit 2204 may receive multi-PRACH transmission from the communication device during operation.

[0093] (Control signal) In the present disclosure, the downlink control signal (information) according to the present disclosure may be a signal (information) transmitted via the PDCCH of the physical layer, or may be a signal (information) transmitted via the MAC Control Element (CE) of the upper layer or RRC. The downlink control signal may be a predefined signal (information).

[0094] The uplink control signal (information) according to the present disclosure may be a signal (information) transmitted via the PUCCH of the physical layer, or may be a signal (information) transmitted via the MAC CE of the upper layer or RRC. Also, the uplink control signal may be a predefined signal (information). The uplink control signal may be uplink control information (UCI), first-stage sidelink control information (SCI), or second-stage SCI.

[0095] (Base station) In the present disclosure, the base station may be, for example, a transmission reception point (TRP), a cluster head, an access point, a remote radio head (RRH), an eNodeB (eNB), a gNodeB (gNB), a base station (BS), a base transceiver station (BTS), a base unit, or a gateway. Also, in sidelink communication, a terminal may be used instead of the base station. The base station may be a relay device that relays communication between the upper node and the terminal. The base station may be a roadside unit.

[0096] (Uplink / Downlink / Sidelink) The present disclosure may be applicable to any of uplink, downlink, and sidelink.

[0097] The present disclosure may be applicable to, for example, uplink channels such as PUSCH, PUCCH, and PRACH, downlink channels such as PDSCH, PDCCH, and PBCH, and sidelink channels such as Physical Sidelink Shared Channel (PSSCH), Physical Sidelink Control Channel (PSCCH), and Physical Sidelink Broadcast Channel (PSBCH).

[0098] PDCCH, PDSCH, PUSCH, and PUCCH are examples of a downlink control channel, a downlink data channel, an uplink data channel, and an uplink control channel, respectively. PSCCH and PSSCH are examples of a sidelink control channel and a sidelink data channel, respectively. PBCH and PSBCH are examples of a broadcast channel, respectively, and PRACH is an example of a random access channel.

[0099] (Data Channel / Control Channel) The present disclosure may be applicable to either a data channel or a control channel. The channels in the present disclosure may be replaced with a data channel including PDSCH, PUSCH, and PSSCH, and / or a control channel including PDCCH, PUCCH, PBCH, PSCCH, and PSBCH.

[0100] (Reference Signal) In the present disclosure, the reference signal is a signal known to both the base station and the mobile station, and each reference signal may be referred to as a reference signal (RS) or a pilot signal. The reference signal can be any one 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).

[0101] (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 sub-slot of a time slot, a mini-slot, or a symbol, an orthogonal frequency division multiplexing (OFDM) symbol, a single carrier-frequency division multiplexing access (SC-FDMA) symbol, or other time resource units. The number of symbols included in one slot is not limited to the number of symbols exemplified in the above-described embodiments, and may be other numbers of symbols.

[0102] (Frequency band) The present disclosure may be applied to either a licensed band or an unlicensed band.

[0103] (Communication) The present disclosure may be applied to any of communication between a base station and a terminal (Uu link communication), communication between terminals (side link communication), and V2X (Vehicle to Everything) communication. The channels in the present disclosure may also be referred to as PSCCH, PSSCH, physical side link feedback channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, and PBCH.

[0104] In addition, the present disclosure can be applied to either a terrestrial network or a non-terrestrial network (NTN) other than a terrestrial network using a satellite or a high-altitude pseudo satellite (HAPS: High Altitude Pseudo Satellite). Further, the present disclosure can also be applied to a network with a large cell size or a terrestrial network with a large delay compared to the symbol length or slot length, such as an ultra-wideband transmission network.

[0105] (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 a single physical antenna, and may refer to an array antenna composed of a plurality of antennas or the like. For example, the number of physical antennas constituting an antenna port is not defined. Instead, an antenna port is defined as the minimum unit that permits a terminal to transmit a reference signal. An antenna port can also be defined as the minimum unit for multiplying precoding vector weights.

[0106] As described above, the embodiments of the present disclosure provide an advanced communication system, communication method, and communication device for multi-PRACH transmission that advantageously bring about the benefit of improved coverage performance among a plurality of PRACH transmissions.

[0107] The present disclosure can be implemented by software, hardware, or software in cooperation with hardware. Each functional block used in the description of the above embodiments can be realized, partially or entirely, as an LSI which is an integrated circuit, and each process described in the above embodiments 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 so as to include part or all of the functional blocks. The LSI may be provided with data input and output. Depending on the degree of integration, the LSI may also be referred to as an IC, a system LSI, a super LSI, or an ultra LSI. The method of integrating into an integrated circuit is not limited to the LSI, and it may be realized by an application specific circuit, a general-purpose processor, or a dedicated processor. Further, after manufacturing the LSI, an FPGA (Field Programmable Gate Array) which can be programmed, or a reconfigurable processor which can reconfigure the connection and setting of circuit cells inside the LSI may be used. The present disclosure can be realized as digital processing or analog processing. Furthermore, if an integrated circuit technology replacing the LSI appears due to the progress of semiconductor technology or another derived technology, naturally, the integration of functional blocks may be performed using that technology. The application of biotechnology or the like is possible as an example.

[0108] The present disclosure can be implemented in any type of apparatus, device, system having a communication function (collectively referred to as a communication device).

[0109] Non-limiting examples of communication devices include telephones (such as mobile phones, smartphones, etc.), tablets, personal computers (PCs) (such as laptops, desktops, notebooks, etc.), cameras (such as digital still / video cameras, etc.), digital players (such as digital audio / video players, etc.), wearable devices (such as wearable cameras, smartwatches, tracking devices, etc.), game consoles, digital book readers, telehealth / telemedicine (remote healthcare / medicine prescription) devices, vehicles or transportation means with communication functions (such as automobiles, airplanes, ships, etc.), and combinations of various devices described above.

[0110] The communication device is not limited to portable or movable ones, and includes all kinds of devices, devices, systems that are not portable or fixed, for example, smart home devices (such as household appliances, lighting devices, smart meters or measuring devices, control panels, etc.), vending machines, and any other "Things" that may exist on the IoT (Internet of Things) network.

[0111] Communication includes data communication by cellular systems, wireless LAN systems, communication satellite systems, etc., as well as data communication by combinations of these.

[0112] In addition, the communication device also includes devices such as control units and sensors that are connected or coupled to a communication device that executes the communication function described in this disclosure. For example, it includes control units and sensors that generate control signals and data signals used by the communication device that executes the communication function of the communication device.

[0113] In addition, the communication device also includes infrastructure facilities, such as base stations, access points, and any other devices, devices, systems that communicate with or control the above non-limiting various devices.

[0114] Although some characteristics of various embodiments have been described with reference to the device, it will be understood that the corresponding characteristics also apply to the methods of the various embodiments, and vice versa.

[0115] Further described below are matters applicable to various embodiments of the present invention.

[0116] Statement 1 A communication device comprising, in operation, a circuit that determines a first UL band that is narrower than a second UL band associated with the communication device, and a transmitter that transmits a multi-PRACH transmission in the first UL band.

[0117] Statement 2 The first UL band is narrower than a threshold value, the second UL band is equal to or wider than the threshold value, and the threshold value is an initial uplink bandwidth part (BWP), a set of resource blocks (RBs), a subset of a plurality of sub-bands into which a serving cell band is divided, or the full bandwidth of a RACH occasion (RO) frequency division multiplexed (FDM) at one time instance, for the communication device according to Statement 1.

[0118] Statement 3 The circuit is further configured to determine, for each PRACH transmission of the multi-PRACH transmission within one or more transmission slots, a RACH occasion (RO) including a duration and a start position, and the transmitter is further configured to transmit the multi-PRACH transmission based on the determined RO, for the communication device according to Statement 1.

[0119] Statement 4 The transmitter is further configured to transmit the multi-PRACH transmission in the first UL band with fewer frequency resources per RO than the frequency resources of the second UL band, for the communication device according to Statement 3.

[0120] Statement 5 The communication device further includes a receiving unit that receives control information related to the multi-PRACH transmission during operation, and the transmitting unit is further configured to transmit the multi-PRACH transmission including a plurality of PRACH transmissions based on the control information. The communication device according to Statement 1.

[0121] Statement 6 The control information indicates a multi-PRACH transmission pattern for one or more transmission slots, and the transmitting unit is further configured to transmit the multi-PRACH transmission through the one or more transmission slots based on the multi-PRACH transmission pattern. The communication device according to Statement 5.

[0122] Statement 7 The control information further indicates different multi-PRACH transmission patterns for each of one or more coverage extension (CE) levels, the circuit is further configured to determine the CE level for the multi-PRACH transmission, and the transmitting unit is further configured to transmit the multi-PRACH transmission based on the multi-PRACH transmission pattern corresponding to the determined CE level. The communication device according to Statement 6.

[0123] Statement 8 The control information further indicates a different number of transmission slots for each of the one or more CE levels, and the transmitting unit is further configured to transmit the multi-PRACH transmission within the number of transmission slots corresponding to the determined CE level. The communication device according to Statement 6.

[0124] Statement 9 The circuit is further configured to determine the duration and start position of each PRACH transmission of the multi-PRACH transmission within the one or more transmission slots, and the transmitting unit is further configured to transmit the multi-PRACH transmission based on the determined duration and start position. The communication device according to Statement 6.

[0125] Statement 10 The circuit determines a plurality of RACH occasions (ROs) including the duration and start position of a subset of the multi-PRACH transmissions within a first slot of the one or more transmission slots, and is further configured to repeat the determined ROs for each remaining slot of the one or more transmission slots. The transmitting unit is further configured to transmit the multi-PRACH transmission via the one or more transmission slots based on the determined ROs. The communication device according to statement 6.

[0126] Statement 11 The circuit is further configured to identify one or more PRACH transmissions of the multi-PRACH transmission that are transmitted across one or more slot boundaries of the one or more transmission slots. The transmitting unit is further configured to transmit the multi-PRACH transmission via the one or more transmission slots without the identified one or more PRACH transmissions. The communication device according to statement 6.

[0127] Statement 12 The circuit identifies one or more PRACH transmissions of the multi-PRACH transmission that are transmitted across one or more slot boundaries of the one or more transmission slots, and is further configured to change the PRACH preamble of the identified PRACH transmissions to enable transmission across the slot boundary. The transmitting 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 statement 6.

[0128] Statement 13 The circuit is further configured to determine a plurality of PRACHs each including dedicated radio resources and / or PRACH preambles for different CE levels, among a plurality of PRACH resources of the multi-PRACH transmission, based on the multi-PRACH transmission pattern, and to determine a CE level for the multi-PRACH transmission. The transmission unit is further configured to perform the multi-PRACH transmission based on each of the plurality of PRACH resources corresponding to the determined CE level. The communication device according to statement 6.

[0129] Statement 14 The circuit is further configured to determine one or more smaller sub-patterns within the multi-PRACH transmission pattern when conditions for handling a collision between any PRACH transmission within the multi-PRACH transmission pattern and a slot boundary, and / or a collision between any PRACH transmission of the multi-PRACH transmission and another uplink transmission or downlink reception having a higher priority are satisfied. The communication device according to statement 9.

[0130] Statement 15 The condition is that the multi-PRACH transmission pattern is longer than the maximum duration of the communication device that can maintain phase continuity and power consistency. The communication device according to statement 14.

[0131] Statement 16 The control information indicates a plurality of ROs for the multi-PRACH transmission. The transmission unit is further configured to transmit the multi-PRACH transmission based on the plurality of indicated ROs. The communication device according to statement 5.

[0132] Statement 17 The communication device according to statement 5, wherein the control information is notified by any one, one or a combination of downlink control information, table-based information, uplink control information, a control element of medium access control (MAC CE), or radio resource control (RRC).

[0133] Statement 18 The communication device according to statement 5, wherein the control information indicates one or more beams for uplink transmission, and the transmission unit is further configured to transmit multi-PRACH transmission using only one of the indicated one or more beams.

[0134] Statement 19 The communication device according to statement 5, wherein the control information indicates one or more beams for uplink transmission, and the transmission unit is further configured to transmit multi-PRACH transmission using a subset of the indicated one or more beams.

[0135] Statement 20 The communication device according to statement 18 or statement 19, wherein the transmission unit is further configured to transmit multi-PRACH transmission only after the communication device reaches the maximum transmission power.

[0136] Statement 21 The communication device according to statement 18 or statement 19, wherein the transmission unit is further configured to transmit multi-PRACH transmission before the communication device reaches the maximum transmission power.

[0137] Statement 22 The communication device according to statement 19, wherein the transmission unit is further configured to transmit coherent multi-PRACH transmission.

[0138] Statement 23 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, the communication device according to statement 5.

[0139] Statement 24 The transmitting unit is further configured to transmit the multi-PRACH transmission in a state where all frequency allocations of ROs in the first UL band are within a subset of a plurality of sub-bands (BW XDD ) of the serving cell in the time domain, the communication device according to statement 3.

[0140] Statement 25 The transmitting unit is further configured to transmit the multi-PRACH transmission based on an SSB-to-RO mapping different from the SSB-to-RO mapping of the second UL band in the first UL band, the communication device according to statement 1.

[0141] Statement 26 The transmitting unit is further configured to transmit the multi-PRACH transmission in the first UL band in a plurality of time symbols or time slots, the communication device according to statement 1.

[0142] Statement 27 The transmitting unit is further configured to transmit the multi-PRACH transmission in the first UL band at a first time instance and in the second UL band at a second time instance, The number of available ROs set at the first time instance used for the multi-PRACH transmission is different from the number of available ROs set at the second time instance, the communication device according to statement 1.

[0143] Statement 28 The communication device according to statement 27, wherein the SSB-to-RO mapping of the first time instance used for the multi-PRACH transmission may be the same as or different from the SSB-to-RO mapping of the second time instance.

[0144] Statement 29 The communication device according to statement 1, wherein the transmitting unit is further configured to transmit the multi-PRACH transmission with an allocation in which the frequency resources per RO are reduced in the first UL band when the maximum UL band associated with the communication device is narrower than a threshold.

[0145] Statement 30 The communication device according to statement 29, wherein the transmitting unit is further configured to transmit the multi-PRACH transmission in the first UL band in a plurality of time symbols or time slots.

[0146] Statement 31 The communication device according to statement 30, wherein the transmitting unit transmits the multi-PRACH transmission such that the number of ROs used for transmission in each of the plurality of time slots is different from each other.

[0147] Statement 32 The communication device according to statement 1, further comprising a receiving unit that receives control information regarding the multi-PRACH transmission during operation, and wherein the transmitting unit is further configured to transmit the multi-PRACH transmission including a plurality of PRACH transmissions based on the control information.

[0148] Statement 33 A base station comprising: a circuit that generates information regarding first and second uplink (UL) bands during operation; a transmitting unit that transmits the information to a communication device during operation; and a receiving unit that receives a multi-PRACH transmission from the communication device during operation.

[0149] Statement 34 A communication method including determining a first uplink (UL) band that is narrower than a second UL band associated with a communication device, and transmitting multi-PRACH transmissions in the first UL band.

[0150] Those skilled in the art will understand that many variations and / or modifications can be made to the present disclosure without departing from the spirit or scope of the present disclosure as broadly described, as shown in the specific embodiments. Therefore, this embodiment should be considered exemplary in all respects and not restrictive.

Claims

1. A communication device, comprising: a circuit that, during operation, determines a first uplink (UL) bandwidth that is narrower than a second UL bandwidth associated with the communication device; a transmitter that, during operation, transmits multi-physical random access channel (PRACH) transmissions in the first UL bandwidth; The communication device comprising the above.

2. The first UL bandwidth is narrower than a threshold value, the second UL bandwidth is equal to or wider than the threshold value, The threshold value is an initial uplink bandwidth part (BWP), a set of resource blocks (RBs), a subset of a plurality of subbands into which a serving cell band is divided, or the entire bandwidth of a RACH occasion (RO) frequency-division multiplexed (FDM) in one time instance. The communication device according to claim 1.

3. The circuit is further configured to determine, for each PRACH transmission of the multi-PRACH transmission within one or more transmission slots, a RACH occasion (RO) including a duration and a start position, and the transmitter is further configured to transmit the multi-PRACH transmission based on the determined RO. The communication device according to claim 1.

4. The transmitter is further configured to transmit the multi-PRACH transmission in the first UL bandwidth with fewer frequency resources per RO than the frequency resources of the second UL bandwidth. The communication device according to claim 3.

5. The transmitting unit is further configured to transmit the multi-PRACH transmission in a state where all the frequency allocations of the ROs in the first UL band are within a subset of a plurality of sub-bands (BW ＸＤＤ ) of the serving cell in the time domain. The communication device according to claim 3.

6. The transmitter is further configured to transmit the multi-PRACH transmission based on an SSB-to-RO mapping that is different from the mapping of the synchronization signal (SSB) of the second UL bandwidth to RO in the first UL bandwidth. The communication device according to claim 1.

7. The transmitter is further configured to transmit the multi-PRACH transmission in the first UL bandwidth in a plurality of time symbols or time slots. The communication device according to claim 1.

8. The transmitter is further configured to transmit the multi-PRACH transmission in the first UL bandwidth at a first time instance and in the second UL bandwidth at a second time instance. The number of available ROs set in the first time instance used for the multi-PRACH transmission is different from the number of available ROs set in the second time instance. The communication device according to claim 1.

9. The SSB-to-RO mapping of the first time instance used for the multi-PRACH transmission may be the same as or different from the SSB-to-RO mapping of the second time instance. The communication device according to claim 8.

10. When the maximum UL bandwidth associated with the communication device is narrower than a threshold, the transmission unit is further configured to transmit the multi-PRACH transmission with an allocation that reduces the frequency resources per RO in the first UL bandwidth. The communication device according to claim 1.

11. The transmission unit is further configured to transmit the multi-PRACH transmission in the first UL bandwidth in a plurality of time symbols or time slots. The communication device according to claim 10.

12. The transmission unit transmits the multi-PRACH transmission such that the number of ROs used for transmission in each of the plurality of time slots is different from each other. The communication device according to claim 11.

13. Further comprising a receiving unit that receives control information regarding the multi-PRACH transmission during operation. The transmission unit is further configured to transmit the multi-PRACH transmission including a plurality of PRACH transmissions based on the control information. The communication device according to claim 1.

14. A circuit that generates information regarding first and second uplink (UL) bands during operation. A transmission unit that transmits the information to a communication device during operation. A receiving unit that receives a multi-PRACH transmission from the communication device during operation. A base station comprising:

15. Determining a first UL bandwidth that is narrower than a second UL bandwidth associated with a communication device. Transmitting a multi-PRACH transmission in the first UL bandwidth. A communication method comprising:

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