Feedback enhancements for multicast broadcast services

Abstract

Systems, methods, and apparatus, are provided for mobile communications. A user equipment (UE) receives a multicast broadcast service (MBS) transport block, where the UE corresponds to a defined state. The defined state can be an RRC inactive or idle state. The UE determines to transmit HARQ feedback for the received MBS transport block. The UE then transmits an indication of the HARQ feedback.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to methods for Hybrid Automatic Repeat Request (HARQ) feedback transmission and methods for Channel State Information (CSI) feedback reporting. BACKGROUND

[0002] Generally, information can be exchanged with computing devices and communication networks. In typical applications, a computing device can request / transmit data with another computing device via a communication network. More specifically, a computing device can utilize a wireless communication network to exchange information or establish a communication channel.

[0003] A wireless communication network can include a variety of devices that include or access components to access the wireless communication network. Such devices can utilize the wireless communication network to facilitate interaction with other devices that have access to the wireless communication network, or through the wireless communication network to facilitate interaction with devices that utilize other communication networks. SUMMARY

[0004] In some embodiments of the present disclosure, a method for Hybrid Automatic Repeat Request (HARQ) feedback transmission is provided. The method includes receiving a Multicast Broadcast Service (MBS) transport block from a base station via a downlink data channel, determining that a received power level of a reference signal is greater than a predetermined threshold, and transmitting HARQ feedback associated with the received MBS transport block.

[0005] In some embodiments of the present disclosure, a method for Hybrid Automatic Repeat Request (HARQ) feedback transmission is provided. The method includes receiving a Multicast Broadcast Service (MBS) transport block, wherein the UE corresponds to a defined state, determining, by the UE, to transmit HARQ feedback for the received MBS transport block, and transmitting the HARQ feedback using a random access procedure based on whether the UE is in the defined state.

[0006] In some embodiments of the present disclosure, a method for Channel State Information (CSI) feedback reporting is provided. The method includes receiving a logical control channel associated with a Multicast Broadcast Service (MBS) via a downlink data channel, wherein the logical control channel carries control information including CSI configuration parameters for CSI measurement and CSI reporting, and wherein the CSI report is associated with the MBS, measuring, by the UE, one or more reference signals based on the CSI configuration parameters, and transmitting a CSI report based on the measured one or more reference signals and based on the CSI configuration parameters.

[0007] In some embodiments of the disclosure, a method for channel state information (CSI) feedback reporting is provided. The method comprises: receiving CSI configuration parameters, the CSI configuration parameters comprising: first CSI configuration parameters associated with multicast broadcast service (MBS); and second CSI configuration parameters associated with unicast service; measuring one or more first reference signals based on the first CSI configuration parameters; measuring one or more second reference signals based on the second CSI configuration parameters; transmitting first CSI reports associated with one or more MBS based on the measurement of the first reference signals; and transmitting second CSI reports associated with one or more unicast services based on the measurement of the second reference signals.

[0008] In some embodiments of the disclosure, an apparatus for mobile communication network is provided. The apparatus comprises: a memory storing instructions; and a processor configured to execute the instructions to: receive channel state information (CSI) configuration parameters, the CSI configuration parameters comprising: first CSI configuration parameters associated with multicast broadcast service (MBS), and second CSI configuration parameters associated with unicast service; measure one or more first reference signals based on the first CSI configuration parameters; measure one or more second reference signals based on the second CSI configuration parameters; transmit first CSI reports associated with one or more MBS based on the measurement of the first reference signals; and transmit second CSI reports associated with one or more unicast services based on the measurement of the second reference signals.

[0009] In some embodiments of the disclosure, a system for mobile communication is provided. The system comprises: a base station configured to transmit channel state information (CSI) configuration parameters to a user equipment (UE), the CSI configuration parameters comprising: first CSI configuration parameters associated with multicast broadcast service (MBS), and second CSI configuration parameters associated with unicast service; and the UE configured to measure one or more first reference signals based on the first CSI configuration parameters, and measure one or more second reference signals based on the second CSI configuration parameters.

[0010] In some embodiments of the disclosure, a non-transitory computer-readable medium is provided. The non-transitory computer-readable medium stores a set of instructions which are executable by at least one processor of an apparatus in a mobile communication system to perform a method. The method comprises: receiving channel state information (CSI) configuration parameters, the channel state information (CSI) configuration parameters comprising: first CSI configuration parameters associated with a multicast broadcast service (MBS), and second CSI configuration parameters associated with a unicast service; measuring one or more first reference signals based on the first CSI configuration parameters; measuring one or more second reference signals based on the second CSI configuration parameters; transmitting a first CSI report associated with one or more MBSs based on the measurement of the first reference signals; and transmitting a second CSI report associated with one or more unicast services based on the measurement of the second reference signals.

[0011] In some embodiments of the disclosure, a non-transitory computer-readable medium is provided. The non-transitory computer-readable medium stores a set of instructions which are executable by at least one processor of an apparatus in a mobile communication system to perform a method. The method comprises: transmitting channel state information (CSI) configuration parameters, the channel state information (CSI) configuration parameters comprising: first CSI configuration parameters associated with a multicast broadcast service (MBS), and second CSI configuration parameters associated with a unicast service; wherein the UE is configured to measure one or more first reference signals based on the first CSI configuration parameters, and to measure one or more second reference signals based on the second CSI configuration parameters. BRIEF DESCRIPTION OF DRAWINGS

[0012] [ Figure 1 ] Figure 1 An example of a mobile communication system is shown, illustrating some aspects in accordance with one or more example embodiments of the disclosure.

[0013] [FIG. 2] Figure 2A and Figure 2B Examples of radio protocol stacks for user and control planes are shown, respectively, illustrating some aspects in accordance with one or more example embodiments of the disclosure.

[0014] [FIG. 3] Figure 3A , Figure 3B and Figure 3C Example mappings between logical channels and transport channels in downlink, uplink, and sidelink are shown, respectively, illustrating some aspects in accordance with one or more example embodiments of the disclosure.

[0015] [FIG. 4] Figure 4A , Figure 4B and Figure 4CExemplary mappings between transport channels and physical channels in downlink, uplink, and sidelink are shown, respectively, in accordance with some aspects of one or more exemplary embodiments of the present disclosure.

[0016] [FIG. 5] Figure 5A , Figure 5B , Figure 5C and Figure 5D Exemplary radio protocol stacks for NR sidelink communication are shown, in accordance with some aspects of one or more exemplary embodiments of the present disclosure.

[0017] [ Figure 6 ] Figure 6 Exemplary physical signals in downlink, uplink, and sidelink are shown, in accordance with some aspects of one or more exemplary embodiments of the present disclosure.

[0018] [ Figure 7 ] Figure 7 Exemplary Radio Resource Control (RRC) states and transitions between different RRC states are shown, in accordance with some aspects of one or more exemplary embodiments of the present disclosure.

[0019] [ Figure 8 ] Figure 8 Exemplary frame structure and physical resources are shown, in accordance with some aspects of one or more exemplary embodiments of the present disclosure.

[0020] [ Figure 9 ] Figure 9 Exemplary component carrier configurations in different carrier aggregation scenarios are shown, in accordance with some aspects of one or more exemplary embodiments of the present disclosure.

[0021] [ Figure 10 ] Figure 10 Exemplary partial bandwidth configurations and switching are shown, in accordance with some aspects of one or more exemplary embodiments of the present disclosure.

[0022] [ Figure 11 ] Figure 11 Exemplary four-step contention-based random access procedures and contention-free random access procedures are shown, in accordance with some aspects of one or more exemplary embodiments of the present disclosure.

[0023] [ Figure 12 ] Figure 12 Exemplary two-step contention-based random access procedures and contention-free random access procedures are shown, in accordance with some aspects of one or more exemplary embodiments of the present disclosure.

[0024] [ Figure 13 ] Figure 13An example time and frequency structure of a synchronization signal and physical broadcast channel (PBCH) block (SSB) illustrating some aspects in accordance with one or more example embodiments of the present disclosure.

[0025] [ Figure 14 ] Figure 14 An example SSB burst transmission illustrating some aspects in accordance with one or more example embodiments of the present disclosure.

[0026] [ Figure 15 ] Figure 15 Example components of a user equipment and a base station for transmission and / or reception illustrating some aspects in accordance with one or more example embodiments of the present disclosure.

[0027] [ Figure 16 ] Figure 16 An example process illustrating some aspects in accordance with one or more example embodiments of the present disclosure.

[0028] [ Figure 17 ] Figure 17 An example process illustrating some aspects in accordance with one or more example embodiments of the present disclosure.

[0029] [ Figure 18 ] Figure 18 An example process illustrating some aspects in accordance with one or more example embodiments of the present disclosure.

[0030] [ Figure 19 ] Figure 19 An example process illustrating some aspects in accordance with one or more example embodiments of the present disclosure.

[0031] [ Figure 20 ] Figure 20 An example process illustrating some aspects in accordance with one or more example embodiments of the present disclosure.

[0032] [ Figure 21 ] Figure 21 An example process illustrating some aspects in accordance with one or more example embodiments of the present disclosure.

[0033] [ Figure 22 ] Figure 22 An example process illustrating some aspects in accordance with one or more example embodiments of the present disclosure.

[0034] [ Figure 23 ] Figure 23 An example process illustrating some aspects in accordance with one or more example embodiments of the present disclosure. ​

[0035] [ Figure 24 ] Figure 24 An example process illustrating some aspects in accordance with one or more example embodiments of the disclosure is shown. DETAILED DESCRIPTION

[0036] The following disclosure provides many different embodiments, or examples, for implementing different characteristics of the provided subject matter. Specific examples of arrangements are described in the following to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting.

[0037] Although the terms“first,”“second,” etc. can be used herein to describe various elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the examples.

[0038] Figure 1 An example of a mobile communication system 100 illustrating some aspects in accordance with one or more example embodiments of the disclosure is shown. The mobile communication system 100 can be operated by a wireless communication system operator such as a Mobile Network Operator (MNO), a private network operator, a Multiple System Operator (MSO), an Internet of Things (IOT) network operator, and the like, and can provide services such as voice, data (e.g., wireless Internet access), messaging, and the like, vehicle communication services such as Vehicle to Everything (V2X) communication services, safety services, mission critical services, services in residential, commercial, or industrial environments such as IOT, industrial IOT (IIOT), and the like.

[0039] The mobile communication system 100 can implement various types of applications having different requirements in terms of latency, reliability, throughput, etc. Example supported applications include enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communication (URLLC), and massive Machine Type Communication (mMTC). eMBB can support stable connections with high peak data rates and moderate rates for cell-edge users. URLLC can support applications with strict requirements in terms of latency and reliability and moderate requirements in terms of data rate. Example mMTC applications include networks of massive IoT devices that are only occasionally active and send small data payloads.

[0040] The mobile communication system 100 can include a Radio Access Network (RAN) part and a core network part. Figure 1The examples shown in the middle show a Next Generation RAN (NG-RAN) 105 and a 5G Core Network (5GC) 110 as examples of a RAN and a core network, respectively. Other examples of RANs and core networks can be implemented without departing from the scope of the disclosure. Other examples of RANs include an Evolved Universal Terrestrial Radio Access Network (EUTRAN), a Universal Terrestrial Radio Access Network (UTRAN), and the like. Other examples of core networks include an Evolved Packet Core (EPC), a UMTS Core Network (UCN), and the like. A RAN implements a Radio Access Technology (RAT) and resides between user equipment (UE) 125 (e.g., UE 125A-UE 125E) and a core network. Examples of such a RAT include New Radio (NR), Long Term Evolution (LTE) (also known as Evolved Universal Terrestrial Radio Access (EUTRA)), Universal Mobile Telecommunication System (UMTS), and the like. The RAT of the example mobile communication system 100 can be NR. A core network resides between a RAN and one or more external networks (e.g., data networks) and is responsible for functions such as mobility management, authentication, session management, establishment of bearers of different Quality of Service (QoS), and applications. The layer of functionality between a UE 125 and a RAN (e.g., NG-RAN 105) can be referred to as the Access Stratum (AS), and the layer of functionality between a UE 125 and a core network (e.g., 5GC 110) can be referred to as the Non-access Stratum (NAS).

[0041] The UE 125 can include wireless transmission and reception components for communicating with one or more nodes in a RAN, one or more relay nodes, or one or more other UEs, etc. Examples of the UE 125 include, but are not limited to, a smartphone, a tablet, a laptop, a computer, a wireless transmission and / or reception unit in a vehicle, a V2X or Vehicle to Vehicle (V2V) device, a wireless sensor, an IOT device, an IIOT device, etc. Other names can be used for the UE 125, such as a Mobile Station (MS), a terminal device, a terminal node, a client device, a mobile device, etc. Further, the UE 125 can also include components or subcomponents integrated into other devices, such as a vehicle, to provide wireless communication functionality with nodes in a RAN, other UEs, satellite communications as described herein. Such other devices can have other or multiple functionalities in addition to wireless communication. Accordingly, references to a UE can include the individual components that facilitate wireless communication as well as the entire device containing the components for facilitating wireless communication.

[0042] A RAN can include nodes (e.g., base stations) for communicating with UEs. For example, the NG-RAN 105 of the mobile communication system 100 can include nodes for communicating with the UEs 125. Different names can be used for the RAN nodes, e.g., depending on the RAT used by the RAN. In a RAN using a UMTS RAT, the RAN nodes can be referred to as Node Bs (NBs). In a RAN using a LTE / EUTRA RAT, the RAN nodes can be referred to as evolved Node Bs (eNBs). For a RAN using a NR RAT, the RAN nodes can be referred to as gNBs. For a RAN using a 5G RAT, the RAN nodes can be referred to as gNBs. Figure 1In the illustrative example of a mobile communication system 100, nodes of the NG-RAN 105 can be next generation Node Bs (gNBs) 115 (e.g., gNBs 115A, 115B) or next generation evolved Node Bs (ng-eNBs) 120 (e.g., ng-eNBs 120A, 120B). In this specification, the terms base station, RAN node, gNB, and ng-eNB can be used interchangeably. The gNBs 115 can provide NR user plane and control plane protocol terminations towards the UEs 125. The ng-eNBs 120 can provide E-UTRA user plane and control plane protocol terminations towards the UEs 125. The interface between a gNB 115 and a UE 125 or between an ng-eNB 120 and a UE 125 can be called a Uu interface. The Uu interface can be established with a user plane protocol stack and a control plane protocol stack. For the Uu interface, the direction from the base station (e.g., gNB 115 or ng-eNB 120) to the UE 125 can be called downlink, and the direction from the UE 125 to the base station (e.g., gNB 115 or ng-eNB 120) can be called uplink.

[0043] The gNBs 115 and the ng-eNBs 120 can be interconnected through the Xn interface. The Xn interface can include an Xn user plane (Xn-U) interface and an Xn control plane (Xn-C) interface. The transport network layer of the Xn-U interface can be established on Internet Protocol (IP) transport and can use the General Packet Radio Service (GPRS) Tunneling Protocol (GTP) over User Datagram Protocol (UDP) / IP to carry user plane Protocol Data Units (PDUs). The Xn-U can provide non-guaranteed delivery of user plane PDUs and can support data forwarding and flow control. The transport network layer of the Xn-C interface can be established on Stream Control Transmission Protocol (SCTP) over IP. The application layer signaling protocol can be referred to as XnAP (Xn Application Protocol). The SCTP layer can provide guaranteed delivery of application layer messages. In the transport IP layer, point-to-point transmission can be used to deliver the signaling PDUs. The Xn-C interface can support Xn interface management, UE mobility management including context transfer and RAN paging, and dual connectivity.

[0044] The gNBs 115 and ng-eNBs 120 can also be connected to the 5GC 110 by NG interfaces, more specifically, to an Access and Mobility Management Function (AMF) 130 (e.g., AMF 130A, AMF 130B) of the 5GC 110 by NG-C interfaces and to a User Plane Function (UPF) 135 (e.g., UPF 135A, UPF 135B) of the 5GC 110 by NG-U interfaces. The transport network layer of the NG-U interface can be built on IP transport and can use the GTP protocol on top of UDP / IP to carry user plane PDUs between the NG-RAN nodes (e.g., gNBs 115 or ng-eNBs 120) and the UPF 135. The NG-U can provide unguaranteed delivery of user plane PDUs between the NG-RAN nodes and the UPF. The transport network layer of the NG-C interface can be built on IP transport. For reliable transport of signaling messages, SCTP can be added on top of IP. The application layer signaling protocol can be referred to as the NGAP (NG Application Protocol). The SCTP layer can provide guaranteed delivery of application layer messages. In transport, point-to-point transport using the IP layer can be used to deliver signaling PDUs. The NG-C interface can provide the following functions: NG interface management; UE context management; UE mobility management; transfer of NAS messages; paging; PDU session management; configuration transfer; warning message transmission.

[0045] The gNB 115 or ng-eNB 120 can host one or more of the following functions: radio resource management functions such as radio bearer control, radio admission control, connection mobility control, dynamic allocation of resources (e.g., scheduling) in uplink and downlink, etc.; IP and Ethernet header compression, ciphering and integrity protection of data; selection of an AMF at a UE Additional Equipment when it is able to determine that there is no routing to an AMF according to the information provided by the UE; routing of user plane data to UPF(s); routing of control plane information to AMF; connection setup and release; scheduling and transmission of paging messages; scheduling and transmission of system broadcast information (e.g., originating from AMF); mobility and scheduling for measurements and measurement reporting configuration; transport level packet marking in uplink; session management; support for network slicing; QoS flow management and mapping to data radio bearers; support of UEs in RRC inactive state; distribution function for NAS messages; network sharing of radio access network; dual connectivity; tight interworking between NR and E-UTRA; and maintaining security and radio configuration for user plane 5G System (5GS) Cellular IoT (CIoT) optimization.

[0046] The AMF 130 can host one or more of the following functions: termination of NAS signaling; NAS signaling security; AS security control; inter-CN node signaling for mobility between 3GPP access networks; idle mode UE reachability (including control and execution of paging retransmission); registration area management; support of intra-system and inter-system mobility; access verification; access authorization including check of roaming rights; mobility management control (subscription and policies); support of network slicing; Session Management Function (SMF) selection; selection of 5GS CIoT optimization.

[0047] The UPF 135 can host one or more of the following functions: anchor point for intra- / inter-RAT mobility when applicable; external PDU session point of interconnect to data network; packet routing and forwarding; user plane part of packet inspection and policy rule enforcement; traffic usage reporting; uplink classifier to support routing traffic flows to the data network; branching point to support multi-homed PDU session; QoS handling for user plane, e.g., packet filtering, gating, UL / DL rate enforcement; uplink traffic verification (Service Data Flow (SDF) to QoS flow mapping); downlink packet buffering and downlink data notification triggering.

[0048] As Figure 1As illustrated in FIG. 1, the NG-RAN 105 can support a PC5 interface between two UEs 125 (e.g., UE 125A and UE 125B). In the PC5 interface, the communication direction between the two UEs (e.g., from UE 125A to UE 125B or vice versa) can be referred to as sidelink. Sidelink transmission and reception over the PC5 interface can be supported when the UEs 125 are in-coverage of the NG-RAN 105, regardless of the RRC state of the UEs, and when the UEs 125 are out-of-coverage of the NG-RAN 105. Support of V2X services via the PC5 interface can be provided by NR sidelink communication and / or V2X sidelink communication.

[0049] PC5-S signaling can be used for unicast link establishment with direct communication request / accept messages. A UE can allocate its source Layer-2 ID for a PC5 unicast link, e.g., based on the V2X service type. During the unicast link establishment procedure, a UE can send its source Layer-2 ID for the PC5 unicast link to a peer UE (e.g., a UE that has already received a destination ID from a higher layer). A pair of source Layer-2 ID and destination Layer-2 ID can uniquely identify a unicast link. The receiving UE can verify that the destination ID belongs to it and can accept the unicast link establishment request from the source UE. During the PC5 unicast link establishment procedure, a PC5-RRC procedure on the access stratum can be invoked for UE sidelink context establishment and AS layer configuration, capability exchange, etc. PC5-RRC signaling can enable exchange of UE capabilities and AS layer configurations such as sidelink radio bearer configuration between a pair of UEs for which a PC5 unicast link is established.

[0050] NR sidelink communication can support one of three transmission modes (e.g., unicast transmission, groupcast transmission, and broadcast transmission) of a pair of source Layer-2 ID and destination Layer-2 ID in the AS. The unicast transmission mode can be characterized by support of one PC5-RRC connection between peer UEs for the pair, transmission and reception of control information and user traffic between peer UEs in the sidelink, support of sidelink HARQ feedback, support of sidelink transmission power control, support of RLC Acknowledged Mode (AM), and detection of radio link failure of the PC5-RRC connection. The groupcast transmission can be characterized by transmission and reception of user traffic between UEs belonging to a group in the sidelink, and support of sidelink HARQ feedback. The broadcast transmission can be characterized by transmission and reception of user traffic between UEs in the sidelink.

[0051] A source Layer-2 ID, a destination Layer-2 ID, and a PC5 link identifier can be used for NR sidelink communications. The source Layer-2 ID can identify a transmitter of data in the NR sidelink communications. The source Layer-2 ID can be a link layer identification that identifies a device or a group of devices that are the receivers of the sidelink communication frames. The destination Layer-2 ID can be a link layer identification that identifies a device that is the transmitter of the sidelink communication frames. In some examples, the source Layer-2 ID and the destination Layer-2 ID can be allocated by a management function in the core network. The source Layer-2 ID can be 24 bits long and can be split into two bit strings in the Medium Access Control (MAC) layer: one bit string can be the LSB part of the source Layer-2 ID (8 bits) and forwarded to the physical layer of the transmitter. This can identify the source of the intended data in the sidelink control information and can be used to filter packets at the physical layer of the receiver. The second bit string can be the MSB part of the source Layer-2 ID (16 bits) and can be carried within the MAC header. This can be used to filter packets at the MAC layer of the receiver. The destination Layer-2 ID can identify a target of data in the NR sidelink communications. For NR sidelink communications, the destination Layer-2 ID can be 24 bits long and can be split into two bit strings in the MAC layer: one bit string can be the LSB part of the destination Layer-2 ID (16 bits) and forwarded to the physical layer of the transmitter. This can identify the target of the intended data in the sidelink control information and can be used to filter packets at the physical layer of the receiver. The second bit string can be the MSB part of the destination Layer-2 ID (8 bits) and can be carried within the MAC header. This can be used to filter packets at the MAC layer of the receiver. The PC5 link identifier can uniquely identify a PC5 unicast link in a UE during the lifetime of the PC5 unicast link. The PC5 link identifier can be used to indicate a PC5 unicast link for which a sidelink Radio Link Failure (RLF) declaration is made and the PC5-RRC connection is released.

[0052] Figure 2A and Figure 2B Examples of radio protocol stacks for user plane and control plane, respectively, are shown illustrating some aspects in accordance with one or more example embodiments of the disclosure. As Figure 2AAs shown in the middle, the protocol stack for the user plane of the Uu interface (between the UE 125 and the gNB 115) includes Service Data Adaptation Protocol (SDAP) 201 and SDAP 211, Packet Data Convergence Protocol (PDCP) 202 and PDCP 212, Radio Link Control (RLC) 203 and RLC 213, layer 2 MAC 204 and MAC 214 sublayers, and Physical (PHY) 205 and PHY 215 layers (layer 1 is also referred to as LI).

[0053] The PHY 205 and PHY 215 provide transport channels 244 to the MAC 204 and MAC 214 sublayers. The MAC 204 and MAC 214 sublayers provide logical channels 243 to the RLC 203 and RLC 213 sublayers. The RLC 203 and RLC 213 sublayers provide RLC channels 242 to the PDCP 202 and PCP 212 sublayers. The PDCP 202 and PDCP 212 sublayers provide radio bearers 241 to the SDAP 201 and SDAP 211 sublayers. Radio bearers can be classified into two groups: Data Radio Bearers (DRBs) for user plane data and Signaling Radio Bearers (SRBs) for control plane data. The SDAP 201 and SDAP 211 sublayers provide QoS flows 240 to the 5GC.

[0054] The main services and functions of the MAC 204 or MAC 214 sublayer include: mapping between logical channels and transport channels; multiplexing / demultiplexing of MAC service data units (SDUs) belonging to one or different logical channels into / from transport blocks (TB) delivered to / from the physical layer on the transport channels; scheduling of reporting information; error correction through hybrid automatic repeat request (HARQ) (one HARQ entity per cell in case of carrier aggregation (CA)); priority handling between UEs by means of dynamic scheduling; priority handling between logical channels within one UE by means of logical channel prioritization (LCP); priority handling between overlapping resources for one UE; and padding. A single MAC entity can support multiple numerologies, transmission timings, and cells. Mapping restrictions in logical channel prioritization will control which numerology(ies), cell(s), and transmission timing(s) a logical channel can use.

[0055] The HARQ function can ensure delivery between peer entities at layer 1. A single HARQ process can support one TB when the physical layer is not configured for downlink / uplink spatial multiplexing, and one or more TBs when the physical layer is configured for downlink / uplink spatial multiplexing.

[0056] The RLC 203 or RLC 213 sublayer can support three transmission modes: transparent mode (TM); unacknowledged mode (UM); and acknowledged mode (AM). The RLC configuration can be per logical channel, independent of numerology and / or transmission duration, and automatic repeat request (ARQ) can operate on any numerology and / or transmission duration for which the logical channel is configured.

[0057] The main services and functions of the RLC 203 or RLC 213 sublayer depend on the transmission mode (e.g., TM, UM, or AM) and can include transfer of upper layer PDUs; in-sequence delivery of upper layer PDUs independent of PDCP (UM and AM) sequence numbering; error correction through ARQ (AM only); segmentation and re-segmentation of RLC SDUs (AM and UM); reassembly of SDUs (AM and UM); duplicate detection (AM only); RLC SDU discard (AM and UM); RLC re-establishment; and protocol error detection (AM only).

[0058] Automatic repeat request within the RLC 203 or RLC 213 sublayer can have the following features: ARQ retransmits RLC SDUs or RLC SDU segments based on RLC status reports; polling for RLC status reports can be used when needed by RLC; RLC receivers can also trigger RLC status reports after detecting missing RLC SDUs or RLC SDU segments.

[0059] The main services and functions of the PDCP 202 or PDCP 212 sublayer can include: data transfer (user plane or control plane); maintenance of PDCP Sequence Number (SN); header compression and decompression using the Robust Header Compression (ROHC) protocol; header compression and decompression using the EHC protocol; ciphering and deciphering; integrity protection and integrity verification; timer-based SDU discard; routing for split bearers; duplication; reordering and in-order delivery; out-of-order delivery; duplicate discard.

[0060] The main services and functions of the SDAP 201 or SDAP 211 include mapping between a QoS flow and a data radio bearer; and marking QoS Flow ID (QFI) in downlink and uplink packets. A single protocol instance of SDAP can be configured per individual PDU session.

[0061] As Figure 2BAs shown in the middle, the protocol stack for the control plane of the Uu interface (between the UE 125 and the gNB 115) includes a PHY layer (layer 1), as well as the MAC, RLC, and PDCP sublayers of layer 2, as described above, in addition to the RRC 206 and RRC 216 sublayers. The main services and functions of the RRC 206 and RRC 216 sublayers on the Uu interface include: broadcast of system information related to AS and NAS; paging initiated by 5GC or NG-RAN; establishment, maintenance, and release of an RRC connection between the UE and the NG-RAN, including addition, modification, and release of carrier aggregation; and addition, modification, and release of dual connectivity in NR or between E-UTRA and NR; security functions, including key management; establishment, configuration, maintenance, and release of SRBs and DRBs; mobility functions, including handover and context transfer; control of UE cell selection and reselection and cell selection and reselection; and inter-RAT mobility; QoS management functions; UE measurement reporting and control of that reporting; detection of and recovery from radio link failure; and transfer of NAS messages from the UE to the NAS / from the NAS to the UE. The NAS 207 and NAS 227 layers are control protocols that perform functions such as authentication, mobility management, security control, etc. (terminating on the network side in the AMF).

[0062] The sidelink-specific services and functions of the RRC sublayer on the Uu interface include: configuration of sidelink resource allocation via system information or dedicated signaling; reporting of UE sidelink information; measurement configuration and reporting related to sidelink; and reporting of UE assistance information for SL traffic pattern(s).

[0063] Figure 3A , Figure 3B and Figure 3CExample mappings between logical channels and transport channels in downlink, uplink, and sidelink according to some aspects of one or more example embodiments of this disclosure are shown. Different types of data transfer services can be provided by the MAC. Each logical channel type can be defined by what type of information is transferred. Logical channels can be classified into two groups: Control Channels and Traffic Channels. Control channels can be used for the transfer of control plane information only. Broadcast Control Channel (BCCH) is a downlink channel used for the transfer of system control information. Paging Control Channel (PCCH) is a downlink channel used for the transfer of paging information. Common Control Channel (CCCH) is a channel for transferring control information between UEs and network. This channel can be used by UEs having no RRC connection with the network. Dedicated Control Channel (DCCH) is a point-to-point bi-directional channel used for the transfer of dedicated control information between a UE and the network and can be used by UEs having an RRC connection. Traffic channels can be used for the transfer of user information. Dedicated Traffic Channel (DTCH) is a point-to-point channel, dedicated to one UE, for the transfer of user information. A DTCH can exist in uplink and downlink. Sidelink Control Channel (SCCH) is a sidelink channel used for the transfer of control information (e.g., PC5-RRC and PC5-S messages) from one UE to another UE(s). Sidelink Traffic Channel (STCH) is a sidelink channel used for the transfer of user information from one UE to another UE(s). Sidelink Broadcast Control Channel (SBCCH) is a sidelink channel used for the broadcast of sidelink system information from one UE to another UE(s).

[0064] Downlink transport channel types include Broadcast Channel (BCH), Downlink Shared Channel (DL-SCH), and Paging Channel (PCH). BCH can be characterized by: fixed, pre-defined transport format; and requirement to be broadcast in the entire coverage area of a cell as a single message or through different BCH instances beamformed. DL-SCH can be characterized by: support for HARQ; support for dynamic link adaptation through varying modulation, coding and transmit power; possibility to be broadcast in the entire cell; possibility to use beamforming; support for dynamic and semi-static resource allocation; and support for UE Discontinuous Reception (DRX) for UE power saving. DL-SCH can be characterized by: support for HARQ; support for dynamic link adaptation through varying modulation, coding and transmit power; possibility to be broadcast in the entire cell; possibility to use beamforming; support for dynamic and semi-static resource allocation; support for UE Discontinuous Reception (DRX) for UE power saving. PCH can be characterized by: support for UE Discontinuous Reception (DRX) for UE power saving (DRX cycle is indicated to the UE by the network); requirement to be broadcast in the entire coverage area of a cell as a single message or through different BCH instances beamformed; mapping to physical resources that can also be dynamically used for traffic / other control channels.

[0065] In the downlink, the following connections between logical channels and transport channels can exist: BCCH can be mapped to BCH; BCCH can be mapped to DL-SCH; PCCH can be mapped to PCH; CCCH can be mapped to DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped to DL-SCH.

[0066] Uplink transport channel types include Uplink Shared Channel (UL-SCH) and Random Access Channel(s) (RACH). UL-SCH can be characterized by: possibility to use beamforming; support for dynamic link adaptation through varying transmit power and possibly modulation and coding; support for HARQ; support for dynamic and semi-static resource allocation. RACH can be characterized by limited control information and risk of collision.

[0067] In the uplink, the following connections between logical channels and transport channels can exist: CCCH can be mapped to UL-SCH; DCCH can be mapped to UL-SCH; and DTCH can be mapped to UL-SCH.

[0068] Sidelink transmission channel types include: Sidelink broadcast channel (SL-BCH) and Sidelink shared channel (SL-SCH). SL-BCH can be characterized by a predefined transport format. SL-SCH can be characterized by: support of unicast, groupcast, and broadcast transmissions; support of UE autonomous resource selection and scheduled resource allocation by the NG-RAN; support of dynamic and semi-persistent resource allocation when the NG-RAN allocates resources to the UE; support of HARQ; and support of dynamic link adaptation by varying the transmission power, modulation, and coding.

[0069] In the sidelink, the following connections between logical channels and transport channels can exist: SCCH can be mapped to SL-SCH; STCH can be mapped to SL-SCH; and SBCCH can be mapped to SL-BCH.

[0070] Figure 4A 、 Figure 4B and Figure 4C respectively show example mappings between transport channels and physical channels in the downlink, uplink, and sidelink, respectively, in accordance with some aspects of one or more example embodiments of the present disclosure. Physical channels in the downlink include Physical Downlink Shared Channel (PDSCH), Physical Downlink Control Channel (PDCCH), and Physical Broadcast Channel (PBCH). PCH and DL-SCH transport channels are mapped to PDSCH. BCH transport channel is mapped to PBCH. Transport channels are not mapped to PDCCH, but rather, PDCCH is used to transmit Downlink Control Information (DCI).

[0071] Physical channels in the uplink include a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), and a physical random access channel (PRACH). A UL-SCH transport channel can be mapped to the PUSCH, and a RACH transport channel can be mapped to the PRACH. Transport channels are not mapped to the PUCCH, but uplink control information (UCI) is transmitted via the PUCCH.

[0072] Physical channels in sidelink include Physical Sidelink Shared Channel (PSSCH), Physical Sidelink Control Channel (PSCCH), Physical Sidelink Feedback Channel (PSFCH), and Physical Sidelink Broadcast Channel (PSBCH). Physical Sidelink Control Channel (PSCCH) can indicate resources and other transmission parameters for PSSCH by the UE. Physical Sidelink Shared Channel (PSSCH) can transport TBs of data itself, as well as control information for HARQ processes and Channel State Information (CSI) feedback triggers, etc. At least six Orthogonal Frequency Division Multiplexing (OFDM) symbols within a slot can be used for PSSCH transmission. Physical Sidelink Feedback Channel (PSFCH) can carry HARQ feedback on sidelink from the UE that is the intended receiver of a PSSCH transmission to the UE that performed the transmission. PSFCH sequences can be transmitted in one PRB repeated over two OFDM symbols near the end of the sidelink resources in a slot. SL-SCH transport channel can be mapped to PSSCH. SL-BCH can be mapped to PSBCH. No transport channels are mapped to PSFCH, but Sidelink Feedback Control Information (SFCI) can be mapped to PSFCH. No transport channels are mapped to PSCCH, but Sidelink Control Information (SCI) can be mapped to PSCCH.

[0073] Figure 5A 、 Figure 5B 、 Figure 5C and Figure 5D An example of a radio protocol stack for NR sidelink communication according to some aspects of one or more example embodiments of the present disclosure is shown. The AS protocol stack for the user plane (i.e., for STCH) in the PC5 interface can consist of SDAP, PDCP, RLC, and MAC sub-layers, and a physical layer. The protocol stack for the user plane is shown in Figure 5A . The AS protocol stack for the SBCCH in the PC5 interface can consist of RRC, RLC, MAC sub-layers, and a physical layer, as shown in Figure 5Bas shown in FIG. 6. To support the PC5-S protocol, the PC5-S sits above the PDCP, RLC, and MAC sub-layers and the physical layer in the control plane protocol stack for the SCCH for PC5-S, as shown in FIG. 6. Figure 5C The AS protocol stack for the control plane of the SCCH for RRC in the PC5 interface consists of the RRC, PDCP, RLC, and MAC sub-layers, and the physical layer. The protocol stack for the control plane of the SCCH for RRC is shown in FIG. 6. Figure 5D

[0074] Sidelink Radio Bearers (SLRBs) can be classified into two groups: Sidelink Data Radio Bearers (SL DRBs) for user plane data and Sidelink Signaling Radio Bearers (SL SRBs) for control plane data. Separate SL SRBs using different SCCHs can be configured for PC5-RRC and PC5-S signaling, respectively.

[0075] The MAC sub-layer can provide the following services and functions over the PC5 interface: radio resource selection; packet filtering; priority handling between uplink transmission and sidelink transmission for a given UE; and sidelink CSI reporting. With logical channel prioritization restrictions in the MAC, only sidelink logical channels belonging to the same destination can be multiplexed as a MAC PDU for each unicast, groupcast, and broadcast transmission that can be associated with a destination. For packet filtering, a SL-SCH MAC header including parts of the source Layer-2 ID and destination Layer-2 ID can be added to the MAC PDU. A Logical Channel Identifier (LCID) included within the MAC subheader can uniquely identify a logical channel within the range of source Layer-2 ID and destination Layer-2 ID combinations.

[0076] The services and functions of the RLC sub-layer can be supported for sidelink. RLC Unacknowledged Mode (UM) and Acknowledged Mode (AM) can be used in unicast transmissions, while only UM can be used in groupcast or broadcast transmissions. For UM, only unidirectional transmissions of groupcast and broadcast can be supported.

[0077] The services and functions of the PDCP sub-layer for the Uu interface can be supported for sidelink with some restrictions as follows: in-sequence delivery can only be supported for unicast transmissions; and repetition can not be supported over the PC5 interface.

[0078] ​The SDAP sublayer can provide the following services and functions over the PC5 interface: mapping between a QoS flow and a sidelink data radio bearer. There can be one SDAP entity per destination for one of unicast, groupcast, and broadcast associated with the destination.

[0079] The RRC sublayer can provide the following services and functions over the PC5 interface: transfer of PC5-RRC messages between peer UEs; maintenance and release of a PC5-RRC connection between two UEs; and detection of a sidelink radio link failure of a PC5-RRC connection based on an indication from MAC or RLC. A PC5-RRC connection can be a logical connection between two UEs for a pair of source Layer-2 ID and destination Layer-2 ID, which can be considered to be established after a corresponding PC5 unicast link is established. There can be a one-to-one correspondence between a PC5-RRC connection and a PC5 unicast link. A UE can have multiple PC5-RRC connections with one or more UEs for different pairs of source Layer-2 and destination Layer-2 IDs. Separate PC5-RRC procedures and messages can be used by a UE to transfer UE capabilities and sidelink configuration including SL-DRB configuration to a peer UE. Two peer UEs can exchange their own UE capabilities and sidelink configuration using separate bi-directional procedures in both sidelink directions.

[0080] Figure 6Example physical signals in downlink, uplink, and sidelink are shown according to some aspects of one or more example embodiments of the present disclosure. Demodulation reference signals (DM-RS) can be used in downlink, uplink, and sidelink and can be used for channel estimation. DM-RS is a UE-specific reference signal and can be transmitted with physical channels in downlink, uplink, or sidelink and can be used for channel estimation and coherent detection of physical channels. Phase tracking reference signals (PT-RS) can be used in downlink, uplink, and sidelink and can be used for tracking phase and mitigating performance loss due to phase noise. PT-RS is mainly used to estimate and minimize the impact of common phase error (CPE) on system performance. Due to phase noise characteristics, PT-RS signals can have low density in frequency domain and high density in time domain. PT-RS can appear in combination with DM-RS and appears when the network configures PT-RS to be present. Positioning reference signals (PRS) can be used in downlink for positioning using different positioning techniques. PRS can be used to measure the time delay of downlink transmissions by correlating the received signal from a base station with a local copy in the receiver. Channel state information reference signals (CSI-RS) can be used in downlink and sidelink. CSI-RS can be used for channel state estimation, reference signal received power (RSRP) measurements for mobility and beam management, time / frequency tracking for demodulation, among other uses. CSI-RS can be configured specifically to a UE, but multiple users can share the same CSI-RS resource. A UE can determine CSI reports and transmit them in uplink to a base station using PUCCH or PUSCH. CSI reports can be carried in a sidelink MAC control element (CE). Primary synchronization signals (PSS) and secondary synchronization signals (SSS) can be used for radio frame synchronization. PSS and SSS can be used during initial access for cell search procedures or for mobility purposes.Sounding Reference Signal, SRS) can be used in uplink for uplink channel estimation. Similar to CSI-RS, SRS can be used as a QCL reference for other physical channels, such that they can be configured and transmitted quasi-co-located with SRS. Sidelink PSS (S-PSS) and Sidelink SSS (S-SSS) can be used for sidelink synchronization.

[0081] Figure 7 An example of radio resource control (RRC) states and transitions between different RRC states is shown, in accordance with some aspects of one or more example embodiments of the present disclosure. A UE can be in one of the following three RRC states: RRC connected state 710, RRC idle state 720, and RRC inactive state 730. After power up, the UE can be in RRC idle state 720, and the UE can establish a connection with the network using initial access and via RRC connection establishment procedure to perform data transfer and / or make / receive voice calls. Once an RRC connection is established, the UE can be in RRC connected state 710. The UE can transition from RRC idle state 720 to RRC connected state 710 or from RRC connected state 710 to RRC idle state 720 using RRC connection establishment / release procedure 740.

[0082] To reduce the signaling load and latency caused by frequent transitions from RRC connected state 710 to RRC idle state 720 when the UE transmits frequent small data, RRC inactive state 730 can be used. In RRC inactive state 730, AS context can be stored by both the UE and the gNB. This can result in faster state transitions from RRC inactive state 730 to RRC connected state 710. The UE can transition from RRC inactive state 730 to RRC connected state 710 or from RRC connected state 710 to RRC inactive state 730 using RRC connection resume / inactive procedure 760. The UE can transition from RRC inactive state 730 to RRC idle state 720 using RRC connection release procedure 750.

[0083] Figure 8An example frame structure and physical resources showing some aspects in accordance with one or more example embodiments of the present disclosure. Downlink or uplink or sidelink transmissions can be organized into frames having a duration of 10 ms consisting of 10 (0 to 9) 1 ms subframes. Each subframe can consist of k slots (k = 1, 2, 4…) where the number of slots k per subframe can depend on the subcarrier spacing of the carrier on which transmissions are made. The slot duration can be 14 symbols (0 to 13) with normal Cyclic Prefix (CP) and 12 symbols with extended CP and can be scaled in time as a function of the subcarrier spacing used, so that there are an integer number of slots in a subframe. Figure 8 A resource grid in time and frequency domains is shown. Each element of the resource grid comprising one time symbol and one frequency subcarrier is referred to as a Resource Element (RE). A Resource Block (RB) can be defined as 12 contiguous subcarriers in the frequency domain.

[0084] In some examples, and in case of non-slot-based scheduling, the transmission of a packet can occur on a portion of a slot, e.g., during two, four, or seven OFDM symbols, which can also be referred to as a mini-slot. Mini-slots can be used for low latency applications, such as URLLC and operation in unlicensed bands. In some embodiments, mini-slots can also be used for fast flexible scheduling of services (e.g., pre-emption of URLLC on eMBB).

[0085] Figure 9 Example component carrier configurations in different carrier aggregation scenarios are shown in accordance with some aspects of one or more example embodiments of the present disclosure. In carrier aggregation (CA), two or more component carriers (CCs) can be aggregated. A UE can simultaneously receive or transmit on one or more CCs according to its capabilities. As shown in Figure 9 As shown in the middle, CA can be supported for contiguous and non-contiguous CCs on the same band or different bands. A gNB and a UE can communicate using a serving cell. The serving cell can be associated with at least one downlink CC (e.g., can be associated with only one downlink CC, or can be associated with downlink CCs and uplink CCs). The serving cell can be a primary cell (PCell) or a secondary cell (SCell).

[0086] A UE can use an uplink timing control procedure to adjust the timing of its uplink transmissions. Timing advance (TA) can be used to adjust the uplink frame timing with respect to the downlink frame timing. A gNB can determine the required timing advance setting and provide it to the UE. The UE can use the provided TA to determine its uplink transmission timing with respect to the downlink reception timing observed by the UE.

[0087] In RRC connected state, the gNB can be responsible for maintaining the timing advance to keep L1 in sync. Serving cells with the same timing advance applied to the uplink and using the same timing reference cell are grouped in a Timing Advance Group (TAG). A TAG can contain at least one serving cell with configured uplink. The mapping of serving cells to TAGs can be configured by RRC. For the primary TAG, the UE can use the PCell as the timing reference cell, except for shared spectrum channel access where an SCell can also be used as the timing reference cell in certain cases. In secondary TAGs, the UE can use any activated SCell of that TAG as the timing reference cell and can not change it unless necessary.

[0088] Timing advance updates can be signaled to the UE by the gNB via MAC CE commands. Such commands can restart a TAG-specific timer that can indicate whether L1 can be synchronized: when the timer is running, L1 can be considered synchronized, otherwise, L1 can be considered non-synchronized (in which case uplink transmissions can only occur on PRACH).

[0089] A UE with single timing advance capability for CA can simultaneously receive and / or transmit on multiple CCs corresponding to multiple serving cells sharing the same timing advance (multiple serving cells grouped in one TAG). A UE with multiple timing advance capability for CA can simultaneously receive and / or transmit on multiple CCs corresponding to multiple serving cells with different timing advances (multiple serving cells grouped in multiple TAGs). The NG-RAN can ensure that each TAG contains at least one serving cell. A UE without CA capability can receive on a single CC and can transmit on a single CC corresponding to only one serving cell (one serving cell in one TAG).

[0090] The multi-carrier nature of the physical layer in the case of CA can be exposed to the MAC layer and each serving cell can require a HARQ entity. When CA is configured, the UE can have one RRC connection with the network. One serving cell (e.g., PCell) can provide NAS mobility information at RRC connection setup / re-establishment / handover. Depending on UE capabilities, SCells can be configured to form together with the PCell a serving cell set. The serving cell set configured for a UE can consist of one PCell and one or more SCells. Reconfiguration, addition and removal of SCells can be performed by RRC.

[0091] In dual connectivity scenarios, a UE can be configured with multiple cells, including a master cell group (MCG) for communication with a master base station, a secondary cell group (SCG) for communication with a secondary base station, and two MAC entities: one for the MCG for communication with the master base station, and one for the SCG for communication with the secondary base station.

[0092] Figure 10 Example partial bandwidth configurations and switching are shown that illustrate some aspects in accordance with one or more example embodiments of the present disclosure. A UE can be configured with one or more partial bandwidths (Bandwidth Parts, BWPs) 1010 (e.g., 1010A, 1010B) on a given member carrier. In some examples, one of the one or more partial bandwidths is active at a time. The active partial bandwidth can define the UE’s active bandwidth within the cell’s operating bandwidth. For initial access, and until receiving a configuration of the UE in the cell, an initial partial bandwidth 1020 can be used that is determined from system information. With bandwidth adaptation (BA), e.g., through BWP switching 1040, the UE’s reception and transmission bandwidth can not be as large as the cell’s bandwidth, and can be adjusted. For example, the width can be commanded to change (e.g., shrink during low activity periods to save power); the location can be moved in the frequency domain (e.g., to increase scheduling flexibility); and the subcarrier spacing can be commanded to change (e.g., to allow different services). The first active BWP 1030 can be the active BWP for the (re)configuration of the PCell or SCell that is activated.

[0093] For a downlink BWP or an uplink BWP in a set of downlink BWPs or uplink BWPs, the UE can be provided with the following configuration parameters: subcarrier spacing (SCS); cyclic prefix; common RB and multiple contiguous RBs; an index of the respective BWP-Id in the set of downlink BWPs or uplink BWPs; a set of BWP common parameters and a set of BWP dedicated parameters. A BWP can be associated with an OFDM numerology according to the configured subcarrier spacing and the cyclic prefix of the BWP. For a serving cell, the UE can be provided with a default downlink BWP in the configured downlink BWPs. If the UE is not provided with a default downlink BWP, the default downlink BWP can be an initial downlink BWP.

[0094] A downlink BWP can be associated with a BWP inactivity timer. If the BWP inactivity timer associated with the active downlink BWP expires, and if a default downlink BWP is configured, the UE can perform a BWP switch to the default BWP. If the BWP inactivity timer associated with the active downlink BWP expires, and if no default downlink BWP is configured, the UE can perform a BWP switch to the initial downlink BWP.

[0095] Figure 11 An example four-step Contention-Based Random Access (CBRA) procedure and a Contention-Free Random Access (CFRA) procedure are shown, in accordance with some aspects of one or more example embodiments of the present disclosure. Figure 12An example two-step contention-based random access (CBRA) procedure and a contention-free random access (CFRA) procedure are shown according to some aspects of one or more example embodiments of the present disclosure. The random access procedure can be triggered by multiple events, e.g., initial access from RRC idle state; RRC connection re-establishment procedure; downlink data arrival or uplink data arrival during RRC connected state when the uplink synchronization status is “non-synchronized”; uplink data arrival during RRC connected state when there is no PUCCH resource available for scheduling request (SR); SR invalidation; requested by RRC at synchronization reconfiguration (e.g., handover); transition from RRC inactive state; time alignment of a second TAG; request for other system information (SI); beam failure recovery (BFR); consistent uplink listen-before-talk (LBT) invalidation.

[0096] Two types of random access (RA) procedures can be supported: 4-step RA type with MSG1 and 2-step RA type with MSGA. Both types of RA procedures can support contention-based random access (CBRA) and contention-free random access (CFRA) as shown in Figure 11 and Figure 12 .

[0097] The UE can select the type of random access at the initiation of the random access procedure based on network configuration. When no CFRA resource is configured, the UE can use an RSRP threshold to select between 2-step RA type and 4-step RA type. When CFRA resource for 4-step RA type is configured, the UE can perform random access with 4-step RA type. When CFRA resource for 2-step RA type is configured, the UE can perform random access with 2-step RA type.

[0098] MSG1 of 4-step RA type can consist of a preamble on PRACH (step 1 of CBRA in Figure 11 ). After MSG1 transmission, the UE can monitor for a response from the network within a configured window (step 2 of CBRA in Figure 11 ). For CFRA, a dedicated preamble for MSG1 transmission can be allocated by the network (step 0 of CFRA in Figure 11 ) and the UE can end the random access procedure as shown in Figure 11 (step 3 of CFRA in Figure 11Steps 1 and 2) of CFRA. For CBRA, upon receiving a random access response (RAR) message (MSG2) (step 2) of CBRA, the UE can transmit MSG3 using the uplink grant scheduled in the RAR message (MSG2) (step 3) of CBRA, and can monitor contention resolution as shown in Figure 11 Figure 11 Steps 2) of CBRA. If contention resolution is unsuccessful after (one or more) MSG3 (re)transmission, the UE can return to MSG1 transmission. Figure 11 Figure 12 Step 4) of CBRA. If contention resolution is unsuccessful after (one or more) MSG3 (re)transmission, the UE can return to MSG1 transmission.

[0099] MSG A of 2-step RA type can include a preamble on PRACH and a payload on PUSCH (e.g., Figure 12 Step A) of CBRA. After MSG A transmission, the UE can monitor for a response from the network within a configured window. For CFRA, a dedicated preamble and PUSCH resource can be configured for MSG A transmission (step 0 and step A) of CFRA, and upon receiving a network response (step 1) of CFRA, the UE can end the random access procedure as shown in Figure 12 Figure 12 Step B) of CFRA, the UE can end the random access procedure as shown in Figure 12 Step B) of CBRA, the UE can end the random access procedure as shown in Figure 12 Step B) of CBRA. If a fallback indication is received in MSG B, the UE can perform MSG3 transmission using the uplink grant scheduled in the fallback indication, and can monitor contention resolution. If contention resolution is unsuccessful after (one or more) MSG3 (re)transmission, the UE can return to MSG A transmission. Figure 13

[0100] Figure 13 An example time and frequency structure of a synchronization signal and physical broadcast channel (PBCH) block (SSB) is shown, illustrating some aspects in accordance with one or more example embodiments of the present disclosure. An SS / PBCH block (SSB) can be composed of a primary and secondary synchronization signal (PSS, SSS), each occupying 1 symbol and 127 subcarriers (e.g., Figure 13 in subcarrier numbers 56 to 182), and the PCBH spans 3 OFDM symbols and 240 subcarriers, but leaves an unused portion in the middle of one symbol for the SSS, as shown in Figure 14 The possible time locations of SSBs within a half frame can be determined by a subcarrier spacing, and the period of the half frame in which SSBs are transmitted can be configured by the network. During a half frame, different SSBs can be transmitted in different spatial directions (i.e., using different beams spanning the coverage area of the cell).​​​​

[0101] The PBCH can be used to carry a Master Information Block (MIB) that is used by the UE during cell search and initial access procedures. The UE can first decode the PBCH / MIB to receive other system information. The MIB can provide the UE with parameters needed to acquire a System Information Block 1 (SIB1), and more specifically, information needed to monitor a PDCCH that schedules a PDSCH carrying the SIB1. In addition, the MIB can indicate cell barring information. The MIB and the SIB1 can be collectively referred to as System Information (SI), and the SIB1 can be referred to as Remaining Minimum System Information (RMSI). Other System Information Blocks (SIBs) (e.g., SIB2, SIB3... SIB10, and SIBpos) can be referred to as other SI. The other SI can be periodically broadcast on a DL-SCH, broadcast on-demand on a DL-SCH (e.g., at the request from a UE in an RRC idle state, an RRC inactive state, or an RRC connected state), or transmitted in a dedicated manner to a UE in an RRC connected state on a DL-SCH (e.g., at the request from a UE in an RRC connected state if configured by the network, or when the UE has an active BWP without a configured common search space).

[0102] Figure 15 An example SSB burst transmission is shown that illustrates some aspects in accordance with one or more example embodiments of the present disclosure. The SSB burst can include N SSBs (e.g., SSB_1, SSB_2... SSB_N), and each of the N SSBs can correspond to a beam (e.g., beam_1, beam_2... beam_N). The SSB burst can be transmitted according to a periodicity (e.g., SSB burst period). During a contention-based random access procedure, a UE can perform a random access resource selection procedure in which the UE first selects an SSB before selecting a RA preamble. The UE can select an SSB with an RSRP above a configured threshold. In some embodiments, the UE can select any SSB if no SSB with an RSRP above the configured threshold is available. A set of random access preambles can be associated with an SSB. After selecting an SSB, the UE can select a random access preamble from the set of random access preambles associated with the SSB, and can transmit the selected random access preamble to start the random access procedure.

[0103] In some embodiments, a beam of the N beams can be associated with a CSI-RS resource (e.g., CSI-RS_1, CSI-RS_2,... CSI-RS_N). The UE can measure the CSI-RS resources and can select a CSI-RS with RSRP above a configured threshold. The UE can select a random access preamble corresponding to the selected CSI-RS and can transmit the selected random access procedure to start a random access procedure. If there is no random access preamble associated with the selected CSI-RS, the UE can select a random access preamble corresponding to an SSB quasi co-located with the selected CSI-RS.

[0104] In some embodiments, based on UE measurements of CSI-RS resources and UE CSI reporting, a base station can determine a Transmission Configuration Indication (TCI) state and can indicate the TCI state to a UE, where the UE can use the indicated TCI state to receive downlink control information (e.g., via PDCCH) or data (e.g., via PDSCH). The UE can use the indicated TCI state to receive data or control information using an appropriate beam. The indication of the TCI state can use a combination of RRC configuration or RRC signaling and dynamic signaling (e.g., via MAC Control Element (MAC CE) and / or based on field values in downlink control information scheduling a downlink transmission). The TCI state can indicate a quasi co-location (QCL) relationship between a downlink reference signal such as a CSI-RS and a DM-RS associated with a downlink control or data channel (e.g., PDCCH or PDSCH, respectively).

[0105] In some embodiments, a UE can be configured with a list of up to M TCI state configurations using physical downlink shared channel (PDSCH) configuration parameters to decode PDSCH according to a detected PDCCH, where the DCI is intended for the UE and a given serving cell, where M can depend on UE capability. Each TCI state can contain parameters for configuring a QCL relationship between one or two downlink reference signals and the DM-RS ports of PDSCH, the DM-RS ports of PDCCH, or the CSI-RS port(s) of a CSI-RS resource. The quasi-co-location relationship can be configured by one or more RRC parameters. The quasi-co-location type corresponding to each DL RS can take one of the following values: "QCL-TypeA": {Doppler shift, Doppler spread, average delay, delay spread}; "QCL-TypeB": {Doppler shift, Doppler spread}; "QCL-TypeC": {Doppler shift, average delay}; "QCL-type": {spatial receive parameter}. The UE can receive an activation command (e.g., MAC CE) for mapping a TCI state to a codepoint of DCI fields.

[0106] Figure 15 Example components of a user equipment and base station for transmission and / or reception are illustrated that can be used in accordance with some aspects of one or more example embodiments of the present disclosure. In one embodiment, Figure 15 The illustrative components of the base station 1505 can be considered as illustrative examples of functional blocks of the illustrative base station 1505. In another embodiment, Figure 15 The illustrative components of the user equipment (UE) 1500 can be considered as illustrative examples of functional blocks of the illustrative user equipment (UE) 1500. Thus, Figure 15 The components illustrated in the user equipment (UE) 1500 and the base station 1505 are not meant to be limiting in scope - that is, the scope of embodiments is not limited to the components depicted in the figures.

[0107] With reference to Figure 15 The antenna 1510 can be used to transmit or receive electromagnetic signals, e.g., for communication with a base station, another user equipment, etc. The antenna 1510 can include one or more antenna elements, and can implement different input-output antenna configurations, including Multiple-Input Multiple-Output (MIMO) configurations, Multiple-Input Single-Output (MISO) configurations, and Single-Input Multiple-Output (SIMO) configurations. In some embodiments, the antenna 1510 can implement massive MIMO configurations with tens or hundreds of antenna elements. The antenna 1510 can implement other multi-antenna techniques, such as beamforming. In some examples and depending on the capabilities of the UE 1500 or the type of UE 1500 (e.g., a low-complexity UE), the UE 1500 can only support a single antenna.

[0108] The transceiver 1520 can communicate bi-directionally, via the antenna 1510, with wireless transceivers, e.g., of base stations, as described herein. For example, the transceiver 1520 can represent a wireless transceiver at a UE and can communicate bi-directionally with a wireless transceiver at a base station, or vice versa. The transceiver 1520 can include a modem to modulate the packets and provide the modulated packets to the antenna 1510 for transmission, and to demodulate packets received from the antenna 1510.

[0109] The memory 1530 can include RAM and ROM. The memory 1530 can store computer-readable, computer-executable code 1535 including instructions that, when executed, cause the processor to perform various functions described herein. In some examples, the memory 1530 can contain, among other computer-readable computer-executable code, a Basic I / O system (BIOS), which can control basic hardware or software operation such as the interaction with peripheral components or devices.

[0110] The processor 1540 can include a hardware device(s) with processing capability (e.g., general purpose processor, a Digital Signal Processor (DSP), a Central Processing Unit (CPU), a microcontroller, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some examples, the processor 1540 can be configured to operate memory using a memory controller. In other examples, a memory controller can be integrated into the processor 1540. The processor 1540 can be configured to execute computer-readable instructions stored in memory (e.g., the memory 1530) to cause the UE 1500 or the base station 1505 to perform various functions.

[0111] The CPU 1550 can perform basic arithmetic, logical, control and input / output (I / O) operations as specified by computer instructions in the memory 1530. The UE 1500 and / or base station 1505 can include additional peripheral components, such as a Graphics Processing Unit (GPU) 1560 and a Global Positioning System (GPS) 1570. The GPU 1560 is a specialized circuit that is used to rapidly manipulate and alter the memory 1530 to accelerate the processing performance of the UE 1500 and / or base station 1505. The GPS 1570 can be used to enable location-based services or other services based on the geographic location of the UE 1500, for example.

[0112] In some examples, the UE 1500 (apparatus) can be configured or programmed for channel state information (CSI) reporting transmission in a mobile communication network. The UE 1500 can include a memory (e.g., memory 1530) storing computer instructions (e.g., code 1535) and a processor (e.g., processor 1540) configured to execute the instructions to receive CSI configuration parameters. The CSI configuration parameters can include first CSI configuration parameters associated with a Multicast Broadcast Service (MBS) and second CSI configuration parameters associated with a unicast service. The processor is further configured to execute the instructions to measure one or more first reference signals based on the first CSI configuration parameters, measure one or more second reference signals based on the second CSI configuration parameters, transmit a first CSI report associated with one or more MBSs based on the measurements of the first reference signals, and transmit a second CSI report associated with one or more unicast services based on the measurements of the second reference signals. In these examples, the memory (e.g., memory 1530) of the UE 1500 can store computer program code (e.g., code 1535) executable by the processor (e.g., CPU 1550) to perform the functions of the UE 1500. Figure 15 Figure 15 In some examples, the base station 1505 can be configured or programmed for CSI reporting transmission in a mobile communication network. The base station 1505 can include a memory (e.g., memory 1530) storing computer instructions (e.g., code 1535) and a processor (e.g., processor 1540) configured to execute the instructions to transmit CSI configuration parameters to a UE (e.g., UE 1500). The CSI configuration parameters can include first CSI configuration parameters associated with a Multicast Broadcast Service (MBS) and second CSI configuration parameters associated with a unicast service. The processor is further configured to execute the instructions to measure one or more first reference signals based on the first CSI configuration parameters, measure one or more second reference signals based on the second CSI configuration parameters, transmit a first CSI report associated with one or more MBSs based on the measurements of the first reference signals, and transmit a second CSI report associated with one or more unicast services based on the measurements of the second reference signals. In these examples, the memory (e.g., memory 1530) of the base station 1505 can store computer program code (e.g., code 1535) executable by the processor (e.g., CPU 1550) to perform the functions of the base station 1505. Figure 15

[0113] In some examples, the base station 1505 can be configured or programmed for CSI reporting transmission in a mobile communication network. The base station 1505 can include a memory (e.g., memory 1530) storing computer instructions (e.g., code 1535) and a processor (e.g., processor 1540) configured to execute the instructions to transmit CSI configuration parameters to a UE (e.g., UE 1500). The CSI configuration parameters can include first CSI configuration parameters associated with a Multicast Broadcast Service (MBS) and second CSI configuration parameters associated with a unicast service. The processor is further configured to execute the instructions to measure one or more first reference signals based on the first CSI configuration parameters, measure one or more second reference signals based on the second CSI configuration parameters, transmit a first CSI report associated with one or more MBSs based on the measurements of the first reference signals, and transmit a second CSI report associated with one or more unicast services based on the measurements of the second reference signals. In these examples, the memory (e.g., memory 1530) of the base station 1505 can store computer program code (e.g., code 1535) executable by the processor (e.g., CPU 1550) to perform the functions of the base station 1505. Figure 15 Figure 16 Figure 17 ​​​​The CSI configuration parameters can include first CSI configuration parameters associated with the MBS and second CSI configuration parameters associated with the unicast service. The UE can be configured to measure one or more first reference signals based on the first CSI configuration parameters and measure one or more second reference signals based on the second CSI configuration parameters. The processor can be configured to execute instructions to transmit downlink control information indicating a request to transmit at least one of a first CSI report or a second CSI report. The downlink control information can trigger the UE to generate and / or transmit at least one of the first CSI report or the second CSI report. In these examples, a memory (e.g., memory 1530) of the base station 1505 can store computer program code (e.g., code 1535) that is executable by a processor (e.g., CPU 1550) to perform the functions of the base station 1505.

[0114] In some examples, the UE 1500 and the base station 1505 are included in a system for mobile communications. The base station can be configured or programmed to transmit CSI configuration parameters to the UE. The CSI configuration parameters can include first CSI configuration parameters associated with the MBS and second CSI configuration parameters associated with the unicast service. In the system, the UE can be configured or programmed to measure one or more first reference signals based on the first CSI configuration parameters and measure one or more second reference signals based on the second CSI configuration parameters.

[0115] In some examples, MBS services can be enabled via a single cell transmission. The MBS can be transmitted within the coverage of a single cell. One or more groupcast / broadcast control channels (e.g., MCCH) and one or more groupcast / broadcast data channels (e.g., MTCH) can be mapped on a DL-SCH. Scheduling can be done by the gNB. Groupcast / broadcast control channel and groupcast / broadcast data channel transmissions can be indicated by a logical channel specific RNTI on the PDCCH. In some examples, a one-to-one mapping between a service identifier, such as a Temporary Mobile Group Identifier (TMGI), and a RAN level identifier, such as a group identifier (G-RNTI) can be used for the DL-SCH to which the groupcast / broadcast data channels can be mapped. In some examples, a single transmission can be used for the DL-SCH associated with groupcast / broadcast control channel and / or groupcast / broadcast data channel transmissions, and HARQ or RLC retransmission can not be used and / or RLC unacknowledged mode (RLC UM) can be used. In other examples, some feedback (e.g., HARQ feedback or RLC feedback) can be used for transmissions via the groupcast / broadcast control channel and / or the groupcast / broadcast data channel.

[0116] In some examples, for a groupcast / broadcast data channel, the following scheduling information can be provided on a groupcast / broadcast control channel: groupcast / broadcast data channel scheduling period, groupcast / broadcast data channel on duration (e.g., a duration that a UE waits to receive a PDCCH after waking up from DRX), groupcast / broadcast data channel inactivity timer (e.g., a time that a UE waits for a successful decoding of a PDCCH, which starts from a most recent successful decoding of a PDCCH indicating a DL-SCH mapped by the groupcast / broadcast data channel, and re-enters DRX if failed).

[0117] In some examples, one or more UE identities can be related to MBS transmissions. The one or more identities can include at least one of: one or more first RNTIs identifying transmissions of a groupcast / broadcast control channel; one or more second RNTIs identifying transmissions of a groupcast / broadcast data channel. The one or more first RNTIs identifying transmissions of a groupcast / broadcast control channel can include a Single Cell RNTI (SC-RNTI, other names can be used). The one or more second RNTIs identifying transmissions of a groupcast / broadcast data channel can include a G-RNTI (nG-RNTI, or other names can be used).

[0118] In some examples, one or more logical channels can be related to MBS transmissions. The one or more logical channels can include a groupcast / broadcast control channel. The groupcast / broadcast control channel can be a point-to-multipoint downlink channel used for transmission of MBS control information from the network to the UE for one or several groupcast / broadcast data channels. The channel can be used by UEs receiving or interested in receiving MBS. The one or more logical channels can include a groupcast / broadcast data channel. The channel can be a point-to-multipoint downlink channel used for transmission of MBS traffic data from the network.

[0119] In some examples, a UE can use a procedure to inform the RAN that the UE is receiving or interested in receiving a MBS service(s) via a MBS radio bearer, and if so, inform the 5G RAN about a priority of MBS reception in a reception only mode over unicast reception or MBS service(s) reception. Figure 18 An example is shown in FIG. 13. A UE can transmit a message (e.g., MBS interest indication message) message to inform the RAN that the UE is receiving / interested in receiving or no longer receiving / interested in receiving a MBS service(s). The UE can transmit the message based on receiving one or more messages (e.g., SIB message or unicast RRC message) from the network, e.g., one or more MBS service area identifiers indicating a current and / or a neighboring carrier frequency.

[0120] In some examples, a UE can consider a MBS service to be part of a MBS service of interest if the UE is capable of receiving the MBS service (e.g., via a single cell point-to-multipoint mechanism); and / or the UE is receiving or interested in receiving the MBS service via a bearer associated with the MBS service; and / or one session of the MBS service is ongoing or is about to start; and / or at least one MBS service identifier of one or more MBS service identifiers indicated by the network is of interest to the UE.

[0121] In some examples, control information for receiving a MBS service can be provided on a specific logical channel (e.g., MCCH). The MCCH can carry one or more configuration messages that indicate ongoing MBS sessions and (corresponding) information about when each session can be scheduled, e.g., a scheduling period, a scheduling window, and a start offset. The one or more configuration messages can provide information about neighboring cells that transmit a MBS session that can be ongoing on the current cell. In some examples, a UE can receive a single MBS service at a time or more than one MBS service in parallel.

[0122] In some examples, MCCH information (e.g., information transmitted in messages transmitted over MCCH) can be transmitted periodically using a configurable repetition period. MCCH transmissions (and associated radio resources and MCS) can be indicated on PDCCH.

[0123] In some examples, a change of MCCH information can occur at specific radio frames / subframes / slots and / or can use a modification period. For example, within a modification period, the same MCCH information can be transmitted multiple times as defined by its scheduling (which is based on the repetition period). The modification period boundary can be defined by SFN values for which SFN mod m = 0, where m is the number of radio frames that comprise the modification period. The modification period can be configured by SIB or RRC signaling.

[0124] In some examples, when the network changes (some) MCCH information, it can inform the UE about the change in the first subframe / slot that can be used for MCCH transmission in the repetition period. Upon receiving the change notification, a UE interested in receiving a MBS service can start acquiring the new MCCH information from the same subframe / slot. The UE can apply the previously acquired MCCH information until the UE acquires the new MCCH information.

[0125] In one example, a system information block (SIB) can contain information needed to acquire control information associated with transmissions of an MBS. The information can include at least one of the following parameters: one or more discontinuous reception (DRX) parameters for monitoring scheduling information of control information associated with transmissions of an MBS, a scheduling period and offset for scheduling information of control information associated with transmissions of an MBS, a modification period for modifying content of control information associated with transmissions of an MBS, repetition information for repeating control information associated with transmissions of an MBS, and the like.

[0126] In one example, an information element (IE) can provide configuration parameters indicating, for example, a list of ongoing MBS sessions transmitted via one or more bearers for each MBS session, one or more associated RNTIs (e.g., G-RNTI, other names can be used), and scheduling information. The configuration parameters can include at least one of the following: one or more timer values for discontinuous reception (DRX) (e.g., an inactivity timer or an on-duration timer), an RNTI for scrambling scheduling and transmission of a multicast / broadcast traffic channel (e.g., MTCH, other names can be used), an ongoing MBS session, one or more power control parameters, one or more scheduling period and / or offset values for one or more MBS traffic channels, information about a list of neighboring cells, and the like.

[0127] Example embodiments can enable RAN functionality for broadcast / groupcast of UEs in RRC CONNECTED state, RRC IDLE state, and RRC INACTIVE state. A group scheduling mechanism can be used to allow UEs to receive broadcast / groupcast services. In some examples, broadcast / groupcast services can be enabled to operate concurrently with unicast reception. In some examples, broadcast / groupcast service delivery can be dynamically changed between groupcast (PTM) and unicast (PTP) with service continuity for a given UE. In some examples, a coordination function can reside in a gNB-CU. In some examples, reliability of broadcast / groupcast services can be improved through UL feedback. The reliability level can be based on requirements of the provided application / service. In some examples, broadcast / groupcast transmission area can be dynamically controlled within one gNB-DU.

[0128] In some examples, Point-to-Multi-point (PTM) (e.g., Single Cell Point-to-Multi-point (SC-PTM) framework) can be used to provide Multicast and Broadcast Service (MBS) services. The SC-PTM framework can also be used for one or more of Mission Critical Push-to-Talk (MCPTT), Internet of Things (IoT), and Vehicle-to-Everything (V2X) communications. In some examples of the Single Cell Point-to-Multi-point framework, the gNB can use the Physical Downlink Shared Channel (PDSCH) to send broadcast data and control information to a group of UEs via one or more cells. In some examples, a first RNTI (e.g., a Group-Specific Radio Network Temporary Identifier (G-RNTI)) can be used to send MBS service data on the PDSCH, and a second RNTI (e.g., a Single Cell Point-to-Multi-point Radio Network Temporary Identifier (SC-RNTI)) can be used to send control information associated with the MBS service on the PDSCH.

[0129] In such Figure 19In some examples, illustrated in FIG. 7, a UE can receive MBS broadcast control information, e.g., using a broadcast channel (e.g., a system information block (SIB)), a groupcast control channel (e.g., a single cell groupcast control channel (SC-MCCH)), and a groupcast traffic channel (e.g., a single cell groupcast traffic channel (SC-MTCH)). For example, MBS broadcast control information (e.g., transmitted via a SIB) can indicate how to receive a groupcast control channel (e.g., a SC-MCCH) that carries MBS related control information. The groupcast control channel can indicate available MBS service identifiers (e.g., temporary mobile group identifiers (TMGIs)) and how to receive a groupcast traffic channel (e.g., a SC-MTCH). The groupcast control channel can also indicate RAN identifiers (e.g., group radio network temporary identifiers (G-RNTIs)) associated with the MBS service identifiers (e.g., TMGIs). For example, the groupcast control channel can indicate a mapping between a TMGI and a G-RNTI. Information carried by the groupcast control channel can remain unchanged for a modification period and can change based on a modification period. The groupcast control channel information can be repeated for a modification period based on a repetition period. The MBS broadcast control information can indicate the modification period and / or the repetition period. The groupcast traffic channel can be used to transmit data for MBS services. The groupcast control channel (e.g., a SC-MCCH) can carry a message (e.g., a SCPTM configuration message) that includes configuration parameters for receiving MBS data via a MBS traffic channel. The configuration parameters can indicate ongoing MBS sessions and information that can schedule each session. The configuration parameters can include a neighbor cell list for potential neighbors that provide the same temporary mobile group identifier (TMGI).

[0130] In some examples, a UE can initially discover and subscribe to MBS services through application layer signaling or through other means such as provisioning in the device. Such service discovery signaling / provisioning can provide the UE with some service identifiers for MBS services to subscribe to. In some examples, the service identifiers can be temporary mobile group identifiers (TMGIs).

[0131] In some examples, when a UE in an RRC connected (RRC CONNECTED) state receives a PDSCH carrying MBS data, the UE can feedback an ACK for successful reception of the PDSCH or a NACK for unsuccessful reception of the PDSCH in the form of uplink control information (UCI). The UE can determine a set of PUCCH resources according to the size of the UCI information. In some examples, the UE can determine a PUCCH resource from the set of resources by using a PUCCH resource indicator field of a DCI scheduling the PDSCH carrying MBS data. In some examples, a gNB can perform unicast-based retransmission based on feedback on the PUCCH resource per UE, or the gNB can perform groupcast-based retransmission if the gNB receives at least one NACK feedback.

[0132] In some examples, multiple UEs can share a common NACK resource for HARQ feedback of MBS data. With a NACK-only feedback mode, a UE can feedback a NACK if the UE has not successfully received a corresponding MBS PDSCH, otherwise the UE can not provide feedback. In some examples, the gNB can configure a PUCCH resource carrying NACK only. In some examples, when the gNB receives at least one NACK feedback on the NACK resource, e.g., based on energy detection, the gNB can perform groupcast-based retransmission.

[0133] In some examples, both HARQ ACK and HARQ NACK feedback can be used. In some examples, a UE can send NACK only, e.g., using a shared PUCCH resource.

[0134] In some examples, a UE-specific ACK / NACK mechanism can be used. A UE can send an ACK if a packet is received correctly, or a NACK if a packet is not received correctly. Each UE has a separate resource to transmit ACK / NACK.

[0135] In some examples, a group NACK mechanism can be used. A UE can send a NACK if a packet is not received correctly, and can not provide feedback if a packet is received correctly. Multiple UEs can share the same resource to transmit NACK.

[0136] In some examples, autonomous / blind retransmission without feedback or with feedback for aggregated PDSCHs can be used. A transmitter can autonomously retransmit data without waiting for feedback for an aggregated set of PDSCHs or bundled feedback for the same TB.

[0137] In some examples, groupcast retransmission based on group NACK can be used. If there is a NACK from at least one UE that was unable to successfully decode the data, the transmitter can retransmit the data.

[0138] In some examples, retransmission can be groupcast or unicast based on UE-specific ACK / NACK feedback. The transmitter can retransmit the data, for example, by using G-RNTI PDSCH or C-RNTI PDSCH based on the number of UEs that failed to receive the initial transmission.

[0139] In some examples, CSI (e.g., CQI, PMI, RI, RSRP / RSRQ, SINR, SRI, CRI, interference conditions) feedback can improve performance through adaptive link adaptation in varying communication environments or help with management / operation of UE grouping.

[0140] In some examples, UEs receiving a PTM transmission can have their own UL resources to send corresponding HARQ feedback. In some examples, PUCCH resources for PTM HARQ feedback can be dedicated to PTM HARQ feedback.

[0141] In some examples, PUCCH resources can be shared by PTM HARQ feedback and PTP HARQ feedback.

[0142] In some examples, UEs can use separate HARQ feedback codebooks for PTM and PTP transmissions.

[0143] In some examples, HARQ feedback codebooks can include HARQ feedback for both PTM and PTP transmissions.

[0144] In some examples, CSI feedback (e.g., CQI / PMI / RI) can be used to improve PTM transmission reliability with higher resource efficiency. With CSI feedback, the gNB can learn the rough direction of the UEs and what is the right MCS to use. In some examples, PTM-specific CSI-RS with different scrambling IDs compared to PTP CSI-RS can be configured, and UEs can measure and report PTM-specific channel-related information. In some examples, UEs in a PTM group can be configured with one or more CSI-RS for PTM and with corresponding CSI reporting configuration.

[0145] In some examples, feedback, such as positive or negative acknowledgement, by a UE, (e.g., HARQ positive / negative acknowledgement or higher layer (such as RLC and / or PDCP) positive / negative acknowledgement) can improve reliability for receiving a multicast broadcast service (MBS) service.

[0146] In some examples, MBS services can be provided using point-to-multipoint (PTM) transmission in a cell. A physical downlink shared channel (PDSCH) of the cell can be used to transmit groupcast / broadcast data and control information by a base station to a group of UEs. For example, data of an MBS service can be transmitted via the PDSCH using a first RNTI (e.g., a group-specific radio network temporary identifier (G-RNTI)), and control information can be transmitted via the PDSCH using a second RNTI (e.g., a single-cell point-to-multipoint (SC-PTM) radio network temporary identifier (SC-RNTI)). In some examples, reliability of MBS services can be enhanced by using a HARQ mechanism and by transmitting HARQ and CSI feedback.

[0147] In some examples, a wide range of MBS use cases can be used, including MBS services, mission critical communications, Internet of Things (IoT), and vehicle-to-everything (V2X), among others. Some MBS use cases can involve transmitting periodic or aperiodic traffic at low to high data rates for a few to thousands of UEs within a cell. In some examples, reliability requirements can vary depending on the MBS use case and / or deployment scenario. UE feedback mechanisms (e.g., for HARQ-based retransmission or CSI feedback) can vary depending on the MBS use case and / or deployment scenario.

[0148] In some examples, retransmission can be at the PDCP and / or RLC sublayer. RLC and / or PDCP retransmission can be sufficient for certain use cases and can not require PHY / MAC-based retransmission (e.g., HARQ-based retransmission). In some examples, RLC and / or PDCP retransmission can not meet the latency and efficiency required for some MBS use cases. In some examples, HARQ can be needed to support MBS transmission. In some examples, a UE can report CSI feedback to improve efficiency and reliability of MBS transmission. In some examples, a UE and a base station can support HARQ for MBS transmission on PDSCH, and the UE can transmit HARQ feedback (e.g., HARQ ACK / NAK) and CSI feedback to the base station to enhance reliability and efficiency of MBS services.

[0149] In Figure 19Example retransmission mechanisms at PDCP / RLC or MAC / PHY retransmission (e.g., HARQ-based retransmission) are shown in FIG. 13. In example retransmission mechanisms, a UE can support blind retransmission of MTCH data with MCCH-scheduled / configured resources. The UE can not transmit HARQ feedback and can use a small number of retransmissions that can be configured based on higher layer retransmission (e.g., PDCP or RLC retransmission). In example retransmission mechanisms, a UE can support synchronous HARQ retransmission based on UE feedback. Resources for retransmission can be predetermined / preconfigured at the first transmission and can be used based on UE feedback if needed. In some examples, synchronous HARQ retransmission can be used by a UE in RRC connected state. In some examples, synchronous HARQ retransmission can be used by a UE in RRC connected, inactive, or idle state and can enhance power efficiency as resources used for possible retransmission can be preconfigured and used by the UE without additional PDCCH monitoring for scheduling resources for retransmission. In example retransmission mechanisms, asynchronous HARQ with incremental redundancy (IR) can be used where retransmission can be dynamically scheduled using downlink control information (e.g., as in unicast). This procedure can be more spectrum efficient. A UE that did not receive an earlier transmission can monitor PDCCH until it receives a retransmitted packet. In some examples, a UE can use one or more of the above retransmission mechanisms.

[0150] In some examples, if a RAN receives a negative acknowledgement (NACK) from only a small number and / or known UEs, the RAN can retransmit the data to such UEs by unicast, otherwise, the retransmission can be groupcast, in which case a UE that has already received the data can ignore such retransmission. In some examples, with synchronous HARQ retransmission, a UE can identify and avoid retransmission of MBS transport blocks that have already been received.

[0151] In some examples, when a UE is configured with HARQ feedback for MBS data, the configuration of such HARQ feedback on the UE can take into account the tradeoff between the QoS / reliability requirements of the MBS service and the power saving and signaling overhead of the UE, as well as the number and range of services of the UE.

[0152] In some examples, various MBS services may be available to the UE. Some of these MBS services may involve long-term transmissions of periodic traffic. In some examples, MBS services can be delivered to UEs in all RRC states. In some examples, UEs in RRC idle / inactive states can transmit their feedback to the network to trigger data retransmission if needed. UEs in RRC idle and inactive states can receive MBS data and, if configured, provide feedback to the network.

[0153] In some examples, if configured by the network, the UE can provide higher-level feedback, such as PDCP / RLC feedback for MBS data delivery. In some examples, the UE can be configured to provide higher-level (e.g., PDCP / RLC) feedback for MBS data delivery issues. In some examples, the UE can provide HARQ feedback regarding MBS data when it is in one of various defined RRC states. For example, the UE can be in an RRC idle state or an RRC inactive state, and if configured by the network, it can provide HARQ feedback. In some examples, if configured by the network, the UE can provide HARQ feedback for MBS data. Figure 19 Example options (i), (ii), (iii), and (iv) for HARQ feedback in connected, idle, and inactive states are shown. In some examples, the UE in all RRC states, including idle / inactive, can be configured to provide HARQ feedback. In some examples, the UE can transition to the RRC connected state to provide HARQ feedback (e.g., Figure 20 Option (i) is in the middle.

[0154] In some examples, HARQ feedback from UEs in RRC idle / inactive states can be supported. In one example, a UE in an RRC idle or inactive state can return to the RRC connection to send negative feedback regarding MBS data reception. In another example, a UE in an RRC idle or inactive state can send HARQ feedback without retuning to the RRC connection state (e.g., Figure 21(ii), (iii), and (iv)). In some examples, for MBS HARQ, the RAN can configure UEs in RRC idle or inactive to transmit HARQ feedback without re-tuning to RRC connected state. For example, for UEs in RRC idle and inactive state, the UEs can use PRACH to transmit HARQ NACK to the RAN and can reserve PRACH resources to allow contention-free access. In some examples, some common PUCCH resources can be configured to be used by such UEs to transmit their feedback. In some examples, UEs in RRC idle or inactive state can use contention-free RACH to transmit HARQ NACK for a given MBS service. The NACK for one or more MBS services can be transmitted via a payload in a selected or designated message based on a particular RACH implementation. For example, according to a two-step RACH implementation, the NACK can be included as a payload in message A. In another example, according to a four-step RACH implementation, the NACK can be included as a payload in message 3. In some examples, the RAN can configure different preambles associated with different MBS services as part of the MBS configuration, and a UE can indicate its NACK for a MBS service by transmitting PRACH with the corresponding preamble. In some examples, UEs in idle or inactive state can be configured with common PUCCH resources to transmit NACK feedback, and UEs in connected state can reuse and share their PUCCH for unicast services for transmitting their MBS feedback.

[0155] In some examples, the number of UEs receiving a MBS can be large, and the network can need to limit the amount of feedback it receives. In some examples, HARQ feedback transmission from UEs for a MBS can be limited to transmission of NACK based on network / RRC configuration. For example, a UE can receive a configuration parameter indicating that HARQ feedback can be transmitted for NACK only or for both ACK and NACK.

[0156] In some examples, HARQ feedback transmission from UEs for a MBS can be limited to UEs within a configured distance from the base station, or based on a threshold of received reference signal received power (RSRP) level.

[0157] In some examples, CSI feedback can be transmitted by UEs to optimize the MCS level and MIMO configuration of MBS data. In some examples, the CSI feedback can be UE configuration specific, and the network can request CSI feedback from a subset of UEs and at certain times.

[0158] In some examples, the network can indicate the CSI-RS resources for the UE to measure the MBS data, and the configured CSI-RS resources can be different from the CSI-RS resources for unicast, e.g., the MBS data can not be beamformed, or can have a wider beam than unicast data transmitted to different UEs within the MBS group. Without such configuration or quasi co-location (QCL) information, the UE can assume the MSB data is transmitted with SSB.

[0159] In some examples, the RAN can indicate the CSI-RS resources / ports for the UE to measure the CSI feedback. Such indication can be sent as a unicast RRC message to the UE directed to send the CSI feedback, or be included in a common MBS configuration available to all UEs.

[0160] In some examples, when the UE is in RRC connected state, the UE can send their CSI feedback based on the MBS data.

[0161] In some examples, given the characteristics of the MBS data transmission, periodic CSI feedback can have limited use, and some multiplexing and design considerations can be needed in the PUCCH configuration. In some examples, the MBS CSI feedback can be based on DCI triggered aperiodic CSI feedback.

[0162] In some examples, the network can direct the UEs to send their CSI feedback using a common PUCCH resource set or based on message 3 / A of 4 / 2-step RACH using one of the specified PRACH resources. In some examples, a subset of UEs to send CSI feedback can be randomly selected using a randomization seed and / or based on signals they receive from the base station. In some examples, the RAN can determine to change the transmission parameters based on the CSI feedback. The CSI feedback can be spread over a time window, so different UEs can send their feedback at different times, a randomization seed can be used.

[0163] In some examples, the network can indicate the CSI-RS resources for the UE to measure the MBS data, and the configured CSI-RS resources can be different from the CSI-RS resources for unicast, e.g., the MBS data can not be beamformed, or can have a wider beam than unicast data transmitted to different UEs within the MBS group. Without such configuration or quasi co-location (QCL) information, the UE can assume the MSB data is transmitted with SSB. Figure 22 In an example embodiment as shown in FIG. 1, a UE can receive one or more messages (e.g., RRC messages) including configuration parameters. The configuration parameters can include configuration parameters of a reference signal. The configuration parameters of the reference signal can indicate radio resources of the reference signal. In some examples, the UE can receive a dedicated RRC message including the configuration parameters of the reference signal. In some examples, the UE can receive a broadcast message (e.g., SIB message) including the configuration parameters of the reference signal. In some examples, the reference signal can include a channel state information reference signal (CSI-RS). In some examples, the reference signal can include a synchronization signal (SSB) reference signal.

[0164] A UE can measure a reference signal based on configuration parameters of the reference signal (e.g., measure a radio resource indicated by the reference signal). The reference signal can be used by the UE to determine whether to transmit HARQ feedback or not to transmit HARQ feedback. In an example, the reference signal can be used by the UE to determine whether to transmit HARQ feedback or not to transmit HARQ feedback for a received transport block associated with a service type (e.g., a multicast broadcast service (MBS) service type). The UE can measure the reference signal and can determine a received power level associated with the reference signal (e.g., a reference signal received power (RSRP) of the reference signal). The UE can determine whether the reference signal received power (RSRP) of the reference signal is above / greater than a threshold. The UE can determine, based on the reference signal measurement, that the reference signal received power is above / greater than the threshold. In some example examples, the threshold can have a predetermined value. In some examples, the UE can receive one or more configuration parameters indicating the threshold. In an example, the UE can be in an RRC idle state or an RRC inactive state. The UE can receive a broadcast message (e.g., a SIB) including one or more configuration parameters indicating the threshold. In an example, the UE can be in an RRC connected state. The UE can receive an RRC message including one or more configuration parameters indicating the threshold.

[0165] A UE can receive a downlink data channel (e.g., a PDSCH) carrying a downlink transport block. The downlink transport block can be an MBS transport block. The UE can receive a downlink MBS transport block via a traffic channel associated with an MBS service (e.g., a Multicast Traffic Channel (MTCH) logical channel). For example, the UE can receive control information indicating scheduling information for the MBS transport block (e.g., via a control channel such as a Multicast Control Channel (MCCH)) and can receive the downlink MBS transport block using scheduling of the scheduling information indicated by the control information.

[0166] The UE can determine whether a received downlink MBS transport block has been successfully received. The UE can determine whether to transmit HARQ feedback associated with the downlink MBS transport block based on a comparison of the received reference signal power with a threshold. For example, the UE can determine to transmit HARQ feedback associated with the received downlink MBS transport block based on the received reference signal power being greater than the threshold. Alternatively, the UE can determine to transmit HARQ feedback associated with the received downlink MBS transport block based on the reference signal power being greater than the threshold and the HARQ feedback being a negative acknowledgment. For example, the UE can transmit HARQ feedback only when the reference signal power is greater than the threshold and the HARQ feedback is NACK. The UE can transmit HARQ feedback associated with the downlink transport block via an uplink control channel. In some examples, the uplink control channel can be specific to the MBS service. In some examples, the uplink control channel can be shared between MBS data and unicast data. In some examples, based on the transmission of HARQ feedback, the UE can receive a retransmission of the downlink MBS transport block.

[0167] In such Figure 23 In the example embodiments shown, the UE may be in a specified state, such as an RRC inactive state or an RRC idle state. The UE may receive MBS transport blocks while in an RRC inactive or RRC idle state. For example, the UE may use radio resources scheduled by control information associated with the MBS service (e.g., control information carried by a multicast control channel, such as the MCCH) to receive downlink MBS transport blocks. The UE may determine whether the downlink MBS transport block has been correctly received (e.g., using a decoding process and / or based on error detection using a Cyclic Redundancy Check (CRC) code). The UE may determine to transmit HARQ feedback for the MBS transport block. For example, the UE may determine to transmit HARQ feedback based on a negative acknowledgment of the HARQ feedback. For example, the UE may determine to transmit HARQ feedback based on a negative acknowledgment of the HARQ feedback and based on comparing the received power level of a reference signal with a threshold. Based on the determination of HARQ feedback for a transport block and the fact that the UE is in an RRC idle or RRC inactive state, the UE can use a random access procedure (e.g., a two-step random access procedure or a four-step random access procedure) to transmit HARQ feedback or an indication of HARQ feedback. For example, one or more messages in the random access procedure can be used to transmit HARQ feedback or an indication of HARQ feedback.

[0168] In some examples, the UE can transition to the RRC connected state based on a random access procedure.

[0169] In some examples, the UE can remain in the RRC inactive state or the RRC idle state (e.g., the UE’s RRC state prior to the indication of the HARQ feedback via the random access procedure) after or prior to completing the random access procedure and after or prior to transmitting the HARQ feedback or the indication of the transmission of the HARQ feedback.

[0170] In some examples, the UE can transition from the RRC inactive state or the RRC idle state (e.g., the UE’s RRC state prior to the indication of the HARQ feedback via the random access procedure) to the RRC connected state based on the random access procedure (e.g., after completing the random access procedure). The UE can transmit the HARQ feedback associated with the MBS transport block via an uplink control channel after transitioning to the RRC connected state. For example, the UE can receive configuration parameters of the uplink control channel via a message 4 (in a four-step random access procedure) or a message B (in a two-step random access procedure).

[0171] In some examples, the UE can transmit a random access preamble to start the random access procedure. The random access preamble can indicate the HARQ feedback. For example, one or more first random access preambles can be configured / preconfigured to indicate a negative acknowledgement (NACK). For example, one or more first random access preambles can be configured / preconfigured to indicate a negative acknowledgement (NACK) and one or more second random access preambles can be configured / preconfigured to indicate a positive acknowledgement (ACK). The base station can determine the HARQ feedback of the UE based on the random access preamble used in the random access procedure. For example, the UE can receive configuration parameters indicating which preambles are used for ACK or NACK indication via dedicated RRC signaling or via a broadcast message (e.g., SIB) indicating that one or more first random access preambles can be used to indicate a NACK and / or indicating that one or more second random access preambles can be used to indicate an ACK.

[0172] In some examples, a random access preamble for a random access procedure can indicate that initiating the random access procedure can be used to provide the HARQ feedback.

[0173] In some examples, the indication of the HARQ feedback can be based on a message 3 of a four-step random access procedure. For example, a payload of the message 3 can indicate the HARQ feedback.

[0174] In some examples, the indication of the HARQ feedback can be based on a message A of a two-step random access procedure. For example, a payload of the message A can indicate the HARQ feedback.

[0175] In some examples, the indication of the HARQ feedback can be based on a message 3 of a four-step random access procedure. For example, a payload of the message 3 can indicate the HARQ feedback. Figure 24In example embodiments as shown in FIG. 1, a UE can transmit HARQ feedback or an indication of HARQ feedback using an uplink control channel based on a determination that a transmission is for a transport block and based on the UE being in an RRC idle or RRC inactive state. The UE can transmit the HARQ feedback or the indication of the HARQ feedback using the uplink control channel while remaining in the RRC idle state or the RRC inactive state. The uplink control channel can be generally configured for a group of UEs (e.g., for a group of UEs in the RRC idle state and / or the RRC inactive state). In some examples, the UE can receive configuration parameters of the uplink control channel via a broadcast message (e.g., a SIB). The configuration parameters can indicate radio resources of the uplink control channel.

[0176] In example embodiments as shown in FIG. 1, a UE can transmit HARQ feedback or an indication of HARQ feedback using an uplink control channel based on a determination that a transmission is for a transport block and based on the UE being in an RRC idle or RRC inactive state. The UE can transmit the HARQ feedback or the indication of the HARQ feedback using the uplink control channel while remaining in the RRC idle state or the RRC inactive state. The uplink control channel can be generally configured for a group of UEs (e.g., for a group of UEs in the RRC idle state and / or the RRC inactive state). In some examples, the UE can receive configuration parameters of the uplink control channel via a broadcast message (e.g., a SIB). The configuration parameters can indicate radio resources of the uplink control channel. ​ In example embodiments as shown in FIG. 1, a UE can transmit HARQ feedback or an indication of HARQ feedback using an uplink control channel based on a determination that a transmission is for a transport block and based on the UE being in an RRC idle or RRC inactive state. The UE can transmit the HARQ feedback or the indication of the HARQ feedback using the uplink control channel while remaining in the RRC idle state or the RRC inactive state. The uplink control channel can be generally configured for a group of UEs (e.g., for a group of UEs in the RRC idle state and / or the RRC inactive state). In some examples, the UE can receive configuration parameters of the uplink control channel via a broadcast message (e.g., a SIB). The configuration parameters can indicate radio resources of the uplink control channel.

[0177] In example embodiments as shown in FIG. 1, a UE can transmit HARQ feedback or an indication of HARQ feedback using an uplink control channel based on a determination that a transmission is for a transport block and based on the UE being in an RRC idle or RRC inactive state. The UE can transmit the HARQ feedback or the indication of the HARQ feedback using the uplink control channel while remaining in the RRC idle state or the RRC inactive state. The uplink control channel can be generally configured for a group of UEs (e.g., for a group of UEs in the RRC idle state and / or the RRC inactive state). In some examples, the UE can receive configuration parameters of the uplink control channel via a broadcast message (e.g., a SIB). The configuration parameters can indicate radio resources of the uplink control channel. ​In example embodiments shown in the middle, a UE can receive one or more messages (e.g., one or more RRC messages, one or more broadcast messages, etc.) including CSI configuration parameters. The CSI configuration parameters can include first CSI configuration parameters for measuring first CSI reference signals and / or reporting first CSI reports associated with MBS services. The CSI configuration parameters can include second CSI configuration parameters for measuring second CSI reference signals and / or reporting second CSI reports associated with one or more unicast services. The UE can measure one or more first reference signals based on the first CSI configuration parameters. For example, the first CSI configuration parameters can indicate first radio resources of the one or more first reference signals, and the UE can measure the one or more first reference signals by measuring the first radio resources. The UE can measure one or more second reference signals based on the second CSI configuration parameters. For example, the second CSI configuration parameters can indicate second radio resources of the one or more second reference signals, and the UE can measure the one or more second reference signals by measuring the second radio resources. The UE can generate first CSI reports associated with one or more MBS services based on the measurements of the one or more first reference signals. The UE can generate second CSI reports associated with one or more unicast services based on the measurements of the one or more second reference signals. In some examples, transmitting the first CSI reports and / or transmitting the second CSI reports can be based on receiving one or more DCIs indicating a request / trigger to transmit the first CSI reports and / or transmit the second CSI reports. For example, a CSI request field of the one or more DCIs can indicate the request / trigger to transmit the first CSI reports and / or transmit the second CSI reports. In some examples, transmitting the first CSI reports and / or transmitting the second CSI reports can be based on periodic CSI reporting. For example, the first CSI configuration parameters or the second CSI configuration parameters can indicate radio resources of the first CSI reports or the second CSI reports.

[0178] In one embodiment, a user equipment (UE) can determine that a received power level of a reference signal is greater than a threshold. The UE can receive, via a downlink data channel and from a base station, a multicast broadcast service (MBS) transport block. The UE can transmit, to the base station, HARQ feedback associated with the MBS transport block based on the received power level of the reference signal being greater than the threshold.

[0179] In some embodiments, the UE can receive a retransmission of the MBS transport block based on the HARQ feedback being negative acknowledgement.

[0180] In some embodiments, transmitting the HARQ feedback associated with the transport block can also be based on the HARQ feedback being negative acknowledgement.

[0181] In some embodiments, a user equipment (UE) can be in a radio resource control (RRC) connected state.

[0182] In some embodiments, a user equipment (UE) can be in one of a radio resource control (RRC) inactive state and an RRC idle state.

[0183] In some embodiments, a UE can receive configuration parameters indicating radio resources of a reference signal. The UE can use the configuration parameters to measure the reference signal. In some embodiments, receiving the configuration parameters can be via one of a broadcast message and a radio resource control (RRC) dedicated message. In some embodiments, the broadcast message can be a system information block (SIB) message.

[0184] In some embodiments, a UE can receive configuration parameters indicating a threshold value. In some embodiments, receiving the configuration parameters can be via one of a broadcast message and a radio resource control (RRC) dedicated message. In some embodiments, the broadcast message can be a system information block (SIB) message.

[0185] In an embodiment, a user equipment (UE) can receive a multicast broadcast service (MBS) transport block in a radio resource control (RRC) inactive state or an RRC idle state. The UE can determine to transmit HARQ feedback for the received MBS transport block. Based on the determination and based on the UE being in the RRC inactive state or the RRC idle state, the UE can use a random access procedure to transmit an indication of the HARQ feedback.

[0186] In some embodiments, a UE can use a random access procedure to transition from the RRC inactive state or the RRC idle state to the RRC connected state. The UE can transmit the HARQ feedback for the MBS transport block after transitioning to the RRC connected state. The UE can transmit the HARQ feedback via an uplink control channel after transitioning to the RRC connected state.

[0187] In some embodiments, the random access procedure can include transmitting a random access preamble, where the random access preamble can indicate the HARQ feedback. In some embodiments, after transmitting the random access preamble, a user equipment (UE) can remain in a radio resource control (RRC) inactive state or an RRC idle state.

[0188] In some embodiments, the UE can receive a configuration parameter indicating that the one or more first random access preambles are for negative acknowledgement. In some embodiments, the UE can receive a configuration parameter indicating that the one or more second random access preambles are for positive acknowledgement. In some embodiments, the UE can receive a broadcast message including the configuration parameter. In some embodiments, the broadcast message can be a system information block (SIB) message.

[0189] In some embodiments, the random access procedure can be a two-step random access procedure. The indication to transmit the HARQ feedback can be made based on a message A of the random access procedure.

[0190] In some embodiments, the random access procedure can be a four-step random access procedure. The indication to transmit the HARQ feedback can be made based on a message 3 of the random access procedure.

[0191] In some embodiments, after the indication to transmit the HARQ feedback, the user equipment (UE) can remain in a radio resource control (RRC) inactive state or an RRC idle state.

[0192] In some embodiments, the random access procedure can include transmitting a random access preamble indicating that the random access procedure is for providing the HARQ feedback.

[0193] In some embodiments, the HARQ feedback can be a negative acknowledgement.

[0194] In some embodiments, determining to transmit the HARQ feedback for the received MBS transport block can be based on whether the HARQ feedback is a negative acknowledgement.

[0195] In one embodiment, a UE in a radio resource control (RRC) inactive state or an RRC idle state can receive a multicast broadcast service (MBS) transport block. The UE can determine to transmit a HARQ feedback for the received MBS transport block. Based on the determination and based on the UE being in the RRC inactive state or the RRC idle state, the UE can transmit an indication of the HARQ feedback using an uplink control channel, where the uplink control channel can be a common uplink control channel for a plurality of UEs in the RRC inactive state or the RRC idle state.

[0196] In some embodiments, the UE can receive one or more broadcast messages including a configuration parameter of the uplink control channel. In some embodiments, the one or more broadcast messages can include a system information block (SIB) message. In some embodiments, the configuration parameter can indicate a radio resource of the uplink control channel.

[0197] In some embodiments, the HARQ feedback can be a negative acknowledgement.

[0198] In some embodiments, determining to transmit HARQ feedback for the received MBS transport block can be based on whether the HARQ feedback is negative acknowledgement.

[0199] In some embodiments, the indication of the HARQ feedback can be transmitted while remaining in the RRC inactive state or the RRC idle state.

[0200] In an embodiment, a UE can receive, via a downlink data channel, a logical control channel associated with a multicast broadcast service (MBS) service, wherein: the logical control channel can carry control information including CSI configuration parameters for CSI measurement and CSI reporting, and the CSI reporting can be associated with the MBS service. The UE can measure one or more reference signals based on the CSI configuration parameters. The UE can transmit the CSI reporting based on the measurement of the reference signals and based on the CSI configuration parameters.

[0201] In some embodiments, the logical control channel can be a logical multicast control channel (MCCH). In some embodiments, the UE can receive scheduling information for receiving the MCCH.

[0202] In some embodiments, the control information can further include scheduling information for receiving a multicast broadcast service (MBS).

[0203] In some embodiments, the channel state information (CSI) configuration parameters can indicate radio resources of one or more reference signals.

[0204] In some embodiments, the UE can receive downlink control information indicating a request to transmit a channel state information (CSI) report.

[0205] In some embodiments, the UE can transmit a channel state information (CSI) report based on a periodic CSI resource. The CSI configuration parameters can indicate the periodic CSI report.

[0206] In an embodiment, a user equipment (UE) can receive CSI configuration parameters including: first CSI configuration parameters associated with a multicast broadcast service (MBS) service; and second CSI configuration parameters associated with a unicast service. The UE can measure one or more first reference signals based on the first CSI configuration parameters. The UE can measure one or more second reference signals based on the second CSI configuration parameters. The UE can transmit a first CSI report associated with one or more MBS services based on the measurement of the first reference signals. The UE can transmit a second CSI report associated with one or more unicast services based on the measurement of the second reference signals.

[0207] In some embodiments, the first channel state information (CSI) configuration parameters can indicate first radio resources of the one or more first reference signals; and the second CSI configuration parameters can indicate second radio resources of the one or more second reference signals.

[0208] In some embodiments, the UE can receive first downlink control information indicating a first request to transmit a first CSI report; and the UE can receive second downlink control information indicating a second request to transmit a second CSI report.

[0209] The example blocks and modules described in this disclosure in relation to various example embodiments can be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination of the above, designed to perform the functions described herein. Examples of a general purpose processor include, but are not limited to, a microprocessor, any conventional processor, a controller, a microcontroller, or a state machine. In some examples, a combination of devices can be used, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0210] The functions described in this disclosure can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. Instructions or code can be stored or transmitted on a computer-readable medium to implement these functions. Other examples of implementing the functions disclosed herein are also within the scope of the disclosure. The implementation of the functions can be via physical elements that are either collectively or distributively positioned (e.g., in different locations), including being distributed such that part of the functions are implemented at different physical locations.

[0211] Computer-readable media includes, but is not limited to, non-transitory computer storage media. Non-transitory storage media can be accessed by a general purpose or special purpose computer. Examples of non-transitory storage media include, but are not limited to, random access memory, read-only memory, electrically erasable programmable memory, flash memory, compact disc read-only memory (CD-ROM), or other optical disk storage, magnetic cased storage or other magnetic storage devices, etc. Non-transitory media can be used to carry or store desired program code means (e.g., instructions and / or data structures) which can be accessed by a general purpose or special purpose computer, or a general-purpose or special-purpose processor. In some examples, software / code can be transmitted from a remote source (e.g., a website, server, etc.) using coaxial cable, fiber optic cable, twisted pair cable, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave. In such examples, the coaxial cable, fiber optic cable, twisted pair cable, DSL, or wireless technologies such as infrared, radio, and microwave are within the definition of medium. Combinations of the above examples are also within the scope of computer-readable media.

[0212] As used in the present disclosure, the use of the term “or” in a list of items indicates an inclusive list. The list of items can be preceded by a phrase such as “at least one of” or “one or more of.” For example, a list of A, B, or C includes A or B or C or AB (i.e., A and B) or AC or BC or ABC (i.e., A and B and C). Also, as used in the present disclosure, a phrase referring to “based on” should not be construed to mean “based only on” a set of conditions, but rather “based at least in part on” a set of conditions. For example, a result described as “based on condition A” can be based on both condition A and condition B without departing from the scope of the present disclosure.

[0213] In this specification, the terms “comprise,” “contain,” or “include,” can be used interchangeably and have the same meaning, and are interpreted to be inclusive and open-ended. The terms “comprise,” “contain,” or “include” can be used before an element list and mean that at least all the listed elements are present, but other elements not in the list can also be present. For example, if A includes B and C, then {B, C} and {B, C, D} are both within the scope of A.

[0214] The present disclosure describes example configurations that are not intended to represent all examples that can be implemented or all configurations within the scope of the present disclosure. The term "exemplary" should not be construed as "preferred" or "advantageous" as compared to other examples, but rather, as "illustrative", "example", or "exemplary". From reading the description of the examples, including the embodiments and the appended drawings, those skilled in the art will be able to devise alternative examples that are within the scope of the present disclosure. Those skilled in the art will appreciate that the examples described herein and / or certain features thereof can be combined with alternative examples and / or certain features of the examples to result in additional examples. Thus, the present disclosure is not limited to the examples described herein, but instead has wide applicability to other situations and examples. Accordingly, the present disclosure is not limited to the examples and designs described herein, but is intended to cover all alternatives, modifications and equivalents falling within the scope of the principles and novel features disclosed herein.

[0215] Clause 1. A method of hybrid automatic repeat request (HARQ) feedback transmission, comprising:

[0216] receiving, by a user equipment (UE), a multicast broadcast service (MBS) transport block via a downlink data channel;

[0217] determining, by the UE, that a received power level of a reference signal is greater than a predetermined threshold; and

[0218] transmitting, by the UE, HARQ feedback associated with the received MBS transport block.

[0219] Clause 2. The method of clause 1, wherein the HARQ feedback corresponds to a negative acknowledgement.

[0220] Clause 3. The method of clause 2, further comprising receiving, in response to the HARQ feedback, a retransmission of the MBS transport block.

[0221] Clause 4. The method of clause 1, wherein a state of the user equipment (UE) corresponds to a radio resource control (RRC) connected state.

[0222] Clause 5. The method of clause 1, wherein a state of the user equipment (UE) corresponds to at least one of a radio resource control (RRC) inactive state and an RRC idle state.

[0223] Clause 6. The method of clause 1, further comprising:

[0224] receiving a configuration parameter indicating a radio resource of the reference signal; and

[0225] measuring the reference signal using the configuration parameter.

[0226] Clause 7. The method of clause 6, wherein receiving the configuration parameters comprises receiving the configuration parameters via one of a broadcast message and a radio resource control (RRC) dedicated message.

[0227] Clause 8. The method of clause 7, wherein the broadcast message is a system information block (SIB) message.

[0228] Clause 9. The method of clause 1, further comprising receiving configuration parameters including the predetermined threshold.

[0229] Clause 10. The method of clause 9, wherein receiving the configuration parameters comprises receiving the configuration parameters via one of a broadcast message and a radio resource control (RRC) dedicated message.

[0230] Clause 11. The method of clause 10, wherein the broadcast message is a system information block (SIB) message.

[0231] Clause 12. A method of hybrid automatic repeat request (HARQ) feedback transmission, comprising:

[0232] receiving, by a user equipment (UE), a multicast broadcast service (MBS) transport block, wherein the UE corresponds to a defined state;

[0233] determining to transmit HARQ feedback for the received MBS transport block; and

[0234] transmitting the HARQ feedback using a random access procedure based on the UE being in the defined state.

[0235] Clause 13. The method of clause 12, further comprising:

[0236] transitioning to an RRC connected state using the random access procedure; and

[0237] transmitting the HARQ feedback for the MBS transport block after transitioning to the RRC connected state.

[0238] Clause 14. The method of clause 13, wherein the transmitting the HARQ feedback comprises transmitting the HARQ feedback via an uplink control channel.

[0239] Clause 15. The method of clause 12, wherein transmitting the HARQ feedback using a random access procedure comprises transmitting a random access preamble, wherein the random access preamble corresponds to the HARQ feedback.

[0240] Clause 16. The method of clause 15, wherein, after transmitting the random access preamble, the user equipment (UE) remains in the defined state.

[0241] Clause 17. The method of clause 12, further comprising: receiving, by the UE, configuration parameters.

[0242] Clause 18. The method of clause 17, wherein receiving, by the UE, the configuration comprises receiving configuration parameters indicating that one or more first random access preambles are for negative acknowledgements.

[0243] Clause 19. The method of clause 17, wherein receiving, by the UE, configuration parameters comprises receiving configuration parameters indicating that one or more second random access preambles are for positive acknowledgements.

[0244] Clause 20. The method of clause 17, wherein receiving, by the UE, configuration parameters comprises receiving a broadcast message including the configuration parameters.

[0245] Clause 21. The method of clause 20, wherein the broadcast message is a system information block (SIB) message.

[0246] Clause 22. The method of clause 12, wherein the random access procedure is a two-step random access procedure.

[0247] Clause 23. The method of clause 22, wherein transmitting the indication of the hybrid automatic repeat request (HARQ) feedback is based on a message A of the two-step random access procedure.

[0248] Clause 24. The method of clause 12, wherein the random access procedure is a four-step random access procedure.

[0249] Clause 25. The method of clause 24, wherein transmitting the indication of the hybrid automatic repeat request (HARQ) feedback is based on a message 3 of the four-step random access procedure.

[0250] Clause 26. The method of clause 12, wherein the defined state comprises at least one of a radio resource control (RRC) inactive state or an RRC idle state.

[0251] Clause 27. The method of clause 12, wherein the hybrid automatic repeat request (HARQ) feedback comprises a negative acknowledgement.

[0252] Clause 28. The method of clause 12, wherein determining to transmit the HARQ feedback for the received groupcast broadcast service (MBS) transport block is based on whether the HARQ feedback is a negative acknowledgement.

[0253] Clause 29. A method of hybrid automatic repeat request (HARQ) feedback transmission, comprising:

[0254] receiving, by a user equipment (UE) in a defined radio resource control (RRC) state, a multicast broadcast service (MBS) transport block;

[0255] determining to transmit HARQ feedback for the received MBS transport block; and

[0256] transmitting, based on the UE being in the defined state, an indication of the HARQ feedback using an uplink control channel, wherein the uplink control channel is a common uplink control channel used by multiple UEs in the defined state.

[0257] Clause 30. The method of clause 29, further comprising receiving, by the user equipment (UE), one or more broadcast messages comprising configuration parameters of the uplink control channel.

[0258] Clause 31. The method of clause 30, wherein the one or more broadcast messages comprise system information block (SIB) messages.

[0259] Clause 32. The method of clause 28, wherein the configuration parameters indicate the radio resources of the uplink control channel.

[0260] Clause 33. The method of clause 29, wherein HARQ feedback comprises a negative acknowledgement.

[0261] Clause 34. The method of clause 29, wherein determining to transmit HARQ feedback for the received MBS transport block comprises determining to transmit the HARQ feedback when the HARQ feedback comprises a negative acknowledgement.

[0262] Clause 35. The method of clause 29, wherein the indication of the HARQ feedback is transmitted while the UE remains in the defined state.

[0263] Clause 36. A method of channel state information (CSI) feedback reporting, comprising:

[0264] receiving, via a downlink data channel, a logical control channel associated with a multicast broadcast service (MBS) service, wherein:

[0265] the logical control channel carries control information comprising CSI configuration parameters for CSI measurement and CSI reporting; and

[0266] the CSI report is associated with the MBS service.

[0267] measure one or more reference signals based on the CSI configuration parameters; and

[0268] transmit a CSI report based on the measurement of the reference signals and based on the CSI configuration parameters.

[0269] Clause 37. The method of Clause 36, wherein the logical control channel is a logical multicast control channel (MCCH).

[0270] Clause 38. The method of Clause 37, further comprising receiving scheduling information for receiving the logical multicast control channel (MCCH).

[0271] Clause 39. The method of Clause 36, wherein the control information further comprises scheduling information for receiving a multicast broadcast service (MBS).

[0272] Clause 40. The method of Clause 36, wherein the channel state information (CSI) configuration parameters indicate radio resources of the one or more reference signals.

[0273] Clause 41. The method of Clause 36, further comprising the user equipment (UE) receiving downlink control information indicating a request to transmit the channel state information (CSI) report.

[0274] Clause 42. The method of Clause 36, wherein transmitting the channel state information (CSI) report comprises transmitting the CSI report based on a periodic CSI resource, and wherein the CSI configuration parameters comprise the periodic CSI resource.

[0275] Clause 43. A method of channel state information (CSI) feedback reporting, comprising:

[0276] receiving, by a user equipment (UE), CSI configuration parameters, the CSI configuration parameters comprising:

[0277] a first CSI configuration parameter associated with a multicast broadcast service (MBS) service; and

[0278] a second CSI configuration parameter associated with a unicast service;

[0279] measuring one or more first reference signals based on the first CSI configuration parameter;

[0280] measuring one or more second reference signals based on the second CSI configuration parameter;

[0281] transmit a first CSI report associated with one or more MBS services based on the measurement of the first reference signal; and

[0282] transmit a second CSI report associated with one or more unicast services based on the measurement of the second reference signal.

[0283] Clause 44. The method of Clause 43, wherein:

[0284] the first channel state information (CSI) configuration parameters indicate first radio resources of the one or more first reference signals; and

[0285] the second CSI configuration parameters indicate second radio resources of the one or more second reference signals.

[0286] Clause 45. The method of Clause 43, further comprising:

[0287] receiving, by the user equipment (UE), first downlink control information indicating a first request to transmit the first channel state information (CSI) report; and

[0288] receiving second downlink control information indicating a second request to transmit the second CSI report.

[0289] Clause 46. An apparatus for use in wireless communication, comprising:

[0290] an antenna to transmit electromagnetic signals;

[0291] a memory to maintain computer-readable code; and

[0292] a processor to execute the computer-readable code, the computer-readable code causing the apparatus to:

[0293] receive a multicast broadcast service (MBS) transport block, wherein the UE corresponds to a defined state;

[0294] determine to transmit HARQ feedback for the received MBS transport block; and

[0295] based on the UE being in the defined state, use a random access procedure to transmit the HARQ feedback.

[0296] Clause 47. The apparatus of Clause 46, wherein the apparatus is further configured to:

[0297] use the random access procedure to transition to an RRC connected state; and

[0298] transmit the HARQ feedback for the MBS transport block after transitioning to the RRC connected state.

[0299] Clause 48. The apparatus of Clause 47, wherein the apparatus transmits the HARQ feedback via an uplink control channel.

[0300] Clause 49. The apparatus of Clause 46, wherein the apparatus transmits a random access preamble, wherein the random access preamble corresponds to the HARQ feedback.

[0301] Clause 50. The apparatus of Clause 49, wherein the apparatus remains in the defined state after transmitting the random access preamble.

[0302] Clause 51. The apparatus of Clause 46, wherein the apparatus receives a configuration parameter.

[0303] Clause 52. The apparatus of Clause 51, wherein the configuration parameter indicates that one or more first random access preambles are for negative acknowledgements.

[0304] Clause 53. The apparatus of Clause 51, wherein the configuration parameter indicates that one or more second random access preambles are for positive acknowledgements.

[0305] Clause 54. The apparatus of Clause 51, wherein the apparatus receives a broadcast message that includes the configuration parameter.

[0306] Clause 55. The apparatus of Clause 54, wherein the broadcast message is a system information block (SIB) message.

[0307] Clause 56. The apparatus of Clause 46, wherein the random access procedure is a two-step random access procedure.

[0308] Clause 57. The apparatus of Clause 56, wherein transmitting the indication of the hybrid automatic repeat request (HARQ) feedback is based on a message A of the two-step random access procedure.

[0309] Clause 58. The apparatus of Clause 46, wherein the random access procedure is a four-step random access procedure.

[0310] Clause 59. The apparatus of Clause 46, wherein transmitting the indication of the hybrid automatic repeat request (HARQ) feedback is based on a message 3 of the four-step random access procedure.

[0311] Clause 60. The apparatus of Clause 46, wherein the defined state comprises at least one of a radio resource control (RRC) inactive state or an RRC idle state.

[0312] Clause 61. The apparatus of Clause 46, wherein the HARQ feedback comprises a negative acknowledgement.

[0313] Clause 62. The apparatus of Clause 46, wherein the apparatus transmitting the HARQ feedback for the received groupcast broadcast service (MBS) transport block is based on whether the HARQ feedback is a negative acknowledgement.

[0314] Clause 63. An apparatus for use in wireless communication comprising:

[0315] an antenna to transmit electromagnetic signals;

[0316] a memory to maintain computer-readable code; and

[0317] a processor to execute the computer-readable code, the computer-readable code causing the apparatus to:

[0318] receive, via a downlink data channel, a logical control channel associated with a groupcast broadcast service (MBS) service, wherein the logical control channel carries control information including CSI configuration parameters for CSI measurement and CSI reporting, and wherein the CSI report is associated with the MBS service;

[0319] measure one or more reference signals based on the CSI configuration parameters; and

[0320] transmit a CSI report based on the measurement of the reference signals and based on the CSI configuration parameters.

[0321] Clause 64. The apparatus of Clause 63, wherein the logical control channel is a logical multicast control channel (MCCH).

[0322] Clause 65. The apparatus of Clause 63, wherein the apparatus receives scheduling information for receiving the logical multicast control channel (MCCH).

[0323] Clause 66. The apparatus of Clause 63, wherein the control information further includes scheduling information for receiving a groupcast broadcast service (MBS).

[0324] Clause 67. The apparatus of Clause 63, wherein the channel state information (CSI) configuration parameters indicate radio resources of the one or more reference signals.

[0325] Clause 68. The apparatus of Clause 63, wherein the apparatus receives downlink control information indicating a request to transmit the channel state information (CSI) report.

[0326] Clause 69. The apparatus of Clause 63, wherein the apparatus transmits the CSI report based on a periodic CSI resource, and wherein the CSI configuration parameters comprise the periodic CSI resource.

[0327] Clause 70. The method of Clause 43, further comprising: receiving, by the UE, downlink control information indicating a request to transmit at least one of the first CSI report or the second CSI report.

[0328] Clause 71. The method of Clause 43, further comprising:

[0329] generating, by the UE, the first CSI report and the second CSI report.

[0330] Clause 72. A base station for a mobile communication system, the base station comprising:

[0331] a memory that stores instructions; and

[0332] a processor configured to execute the instructions to:

[0333] transmit, to a user equipment (UE), channel state information (CSI) configuration parameters, the channel state information (CSI) configuration parameters comprising:

[0334] first CSI configuration parameters associated with a multicast broadcast service (MBS); and

[0335] second CSI configuration parameters associated with a unicast service;

[0336] wherein the UE is configured to measure one or more first reference signals based on the first CSI configuration parameters and one or more second reference signals based on the second CSI configuration parameters.

[0337] Clause 73. The base station of Clause 72, wherein the processor is configured to execute the instructions to:

[0338] transmit downlink control information indicating a request to transmit at least one of a first CSI report or a second CSI report.

[0339] Clause 74. The base station of Clause 72, wherein the downlink control information triggers the UE to generate at least one of the first CSI report or the second CSI report.

[0340] Clause 75. A method of hybrid automatic repeat request (HARQ) feedback reception, comprising:

[0341] transmitting, by a base station, a multicast broadcast service (MBS) transport block via a downlink data channel;

[0342] receiving, by the base station, HARQ feedback associated with the transmitted MBS transport block.

[0343] Clause 76. A method of hybrid automatic repeat request (HARQ) feedback reception, comprising:

[0344] transmitting, by a base station, a multicast broadcast service (MBS) transport block, the multicast broadcast service (MBS) transport block receivable by a user equipment (UE) corresponding to a defined state;

[0345] receiving HARQ feedback for the MBS transport block transmitted based on the UE being in the defined state, wherein the MBS transport block is transmitted using a random access procedure to transmit the HARQ feedback.

[0346] Clause 77. A method of hybrid automatic repeat request (HARQ) feedback reception, comprising:

[0347] transmitting, by a base station, a multicast broadcast service (MBS) transport block, the multicast broadcast service (MBS) transport block receivable by a user equipment (UE) in a defined radio resource control (RRC) state;

[0348] receiving an indication of HARQ feedback using an uplink control channel, wherein the indication is transmitted based on the UE being in the defined state, and wherein the uplink control channel is a common uplink control channel used by a plurality of UEs.

[0349] Clause 78. A method of channel state information (CSI) feedback reception, comprising:

[0350] transmitting, by a base station, a logical control channel associated with a multicast broadcast service (MBS) via a downlink data channel, wherein the logical control channel carries control information including CSI configuration parameters for CSI measurement and CSI reporting, and wherein the CSI reporting is associated with the MBS,

[0351] transmitting one or more reference signals; and

[0352] receiving a CSI report based on measurement of at least one of the one or more reference signals and based on the CSI configuration parameters.

[0353] Clause 79. A method of channel state information (CSI) feedback reception, comprising:

[0354] transmitting, by a base station, CSI configuration parameters, the CSI configuration parameters including:

[0355] a first CSI configuration parameter associated with multicast broadcast services (MBS); and

[0356] a second CSI configuration parameter associated with unicast services;

[0357] transmit one or more first reference signals based on the first CSI configuration parameter;

[0358] transmit one or more second reference signals based on the second CSI configuration parameter;

[0359] receive a first CSI report associated with one or more MBS based on measurements of at least one of the one or more first reference signals; and

[0360] receive a second CSI report associated with one or more unicast services based on measurements of at least one of the one or more second reference signals.

[0361] This application claims the benefit of U.S. Provisional Application No. 63 / 090,409, entitled “FEEDBACK ENHANCEMENT FOR MULTICAST BROADCAST SERVICES,” filed October 12, 2020. U.S. Provisional Application No. 63 / 090,409 is incorporated by reference herein.

Claims

1. A method for a user equipment, comprising: receiving multicast broadcast service data from a radio access network node via a downlink data channel; receiving first information from the radio access network node for determining whether to transmit hybrid automatic repeat request feedback for the multicast broadcast service data only for negative acknowledgement or for both acknowledgement and negative acknowledgement; and transmitting hybrid automatic repeat request feedback for the multicast broadcast service data to the radio access network node based on the first information.

2. The method of claim 1, wherein, the first information is received via one of a broadcast message and a radio resource control dedicated message. 3.The method of claim 1, further comprising: receiving second information from the radio access network node for determining whether to transmit hybrid automatic repeat request feedback for the multicast broadcast service data before receiving the multicast broadcast service data; and transmitting hybrid automatic repeat request feedback for the multicast broadcast service data to the radio access network node based on the second information.

4. The method of claim 3, wherein, the second information is received via one of a broadcast message and a radio resource control dedicated message.

5. The method of claim 1, further comprising: receiving retransmission of the multicast broadcast service data in response to the hybrid automatic repeat request feedback.

6. The method of claim 1, wherein, a state of the user equipment corresponds to a radio resource control connected state.

7. The method of claim 1, wherein, a state of the user equipment corresponds to at least one of a radio resource control inactive state and a radio resource control idle state. 8.A user equipment, comprising: receiving circuitry configured to receive multicast broadcast service data from a radio access network node via a downlink data channel, wherein the receiving circuitry is configured to receive first information from the radio access network node for determining whether to transmit hybrid automatic repeat request feedback for the multicast broadcast service only for negative acknowledgement or for both acknowledgement and negative acknowledgement; and transmitting circuitry configured to transmit hybrid automatic repeat request feedback for the multicast broadcast service data to the radio access network node based on the determination. 9.A method for a radio access network node, comprising: transmitting multicast broadcast service data to a user equipment via a downlink data channel; transmitting first information to the user equipment for the user equipment to determine whether to transmit hybrid automatic repeat request feedback only for negative acknowledgement or for both acknowledgement and the negative acknowledgement based on the first information; and receiving hybrid automatic repeat request feedback for the multicast broadcast service data from the user equipment based on the first information. 10.A radio access network node, comprising: transmitting circuitry configured to transmit multicast broadcast service data to a user equipment via a downlink data channel, wherein the transmitting circuitry is configured to transmit first information to the user equipment for the user equipment to determine whether to transmit hybrid automatic repeat request feedback for the multicast broadcast service data only for negative acknowledgement or for both acknowledgement and the negative acknowledgement; and receiving circuitry configured to receive the hybrid automatic repeat request feedback for the multicast broadcast service data from the user equipment based on the first information. ​

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