Wireless communication method and related equipment

Abstract

The invention provides a wireless communication method which is executed by user equipment (UE) in a network, and the method comprises the following steps: receiving multicast service in an inactive state; a small data transmission (SDT) process is triggered to send hybrid automatic repeat request (HARQ) feedback for the multicast service during the inactive state. According to the method, the reliability of multicast service transmission in the inactive state can be improved.

Description

Technical Field

[0001] The present invention relates to wireless communication technology, and more specifically, to a wireless communication method and related equipment such as a user equipment UE and a base station BS (e.g., gNB). Background Art

[0003] The wireless communication systems of the third generation (3G) mobile phone standards and technologies are well known. Such 3G standards and technologies were developed by the Third Generation Partnership Project (3GPP). The third generation of wireless communication was developed to support macrocellular mobile phone communications, so that the communication systems and networks are moving towards broadband and mobile systems. In a cellular wireless communication system, a user equipment (UE) is connected to a radio access network (RAN) via a radio link. The RAN includes a set of base stations (BS) that provide a radio link with the UE in the cell covered by the base station and an interface to the core network (CN), the former providing a radio link with the UE in the cell covered by the base station and the latter providing overall network control. The RAN and the CN each perform their own functions related to the entire network. The Third Generation Partnership Project developed the Long Term Evolution (LTE) system, the Evolved Universal Mobile Telecommunications System Radio Access Network (E-UTRAN), for mobile access networks, in which one or more macro base stations are supported by base stations called eNodeB or eNB (evolved NodeB). LTE is further developing towards the so-called 5G or NR (New Radio) system, in which one or more cells are supported by base stations called next generation NodeB base stations (gNB).

[0004] In LTE, if the UE is inactive for a period of time, the network can command the UE to enter the RRC_IDLE state to reduce the power consumption of the UE. Whenever the UE needs to perform certain activities, the UE needs to transition from the RRC_IDLE state to the RRC_CONNECTED state. Since a small amount of data must be sent very frequently in current mobile communication applications, frequent idle-connected-idle state transitions increase network signaling load and delay. Therefore, 5G NR defines a new state called RRC_INACTIVE to reduce the network signaling load and delay involved in the transition to the RRC_CONNECTED state. In NR, when the RRC connection is established, the UE is in the RRC_CONNECTED state, and when the RRC connection is suspended, the UE is in the RRC_INACTIVE state. Otherwise, the UE is in the RRC_IDLE state, that is, the RRC connection is not established. The RRC_INACTIVE and RRC_IDLE states can be called energy-saving states. More specifically, in the RRC_INACTIVE state, the UE access stratum (AS) context is stored in the UE and the network to maintain the core network connection (i.e., the UE remains in the Connection Management (CM)-Connected state) and release the Radio Access Network (RAN) connection. The network can deliver inactive UEs via RAN or CN paging messages.

[0005] The UE performs a random access (RA) procedure to access the network. The RA procedure can be divided into contention-free random access (CFRA) type and contention-based random access (CBRA) type. The contention-free or contention-based RA procedure can be a four-step procedure or a two-step procedure. Taking the four-step contention-based random access RA procedure as an example, the UE transmits a contention-based physical random access channel (PRACH) preamble, also known as MSG1. After detecting the preamble, the gNB responds with a random-access response (RAR), also known as MSG2. The RAR includes an uplink grant for scheduling a physical uplink shared channel (PUSCH) transmission (called MSG3) from the UE. In response to the RAR, the UE transmits MSG3, including an ID for contention resolution. After receiving MSG3, the network transmits a contention resolution message with a contention resolution solution ID, also known as MSG4. The UE receives MSG4 and if the UE finds its contention resolution ID, it sends an acknowledgment on the Physical Uplink Control Channel (PUCCH), completing the four-step random access procedure. The two-step RA procedure reduces latency and control signaling overhead by implementing a single round-trip cycle between the UE and the base station. This is achieved by combining the preamble (MSG1) and the scheduled PUSCH transmission (MSG3) into a single message from the UE to the gNB, called MSGA, and combining the random access response MSG2 and the contention resolution message MSG4 into a single message MSGB from the gNB to the UE. If a dedicated preamble is provided to the UE, the two-step process and the four-step process can be applied to CFRA.

[0006] "NR Small Data Transmissions (SDT) in Inactive State" was introduced and specified in R17. Basically it is as follows: "NR supports the RRC_INACTIVE state and UEs with infrequent data transmission (periodic and / or aperiodic) are generally maintained by the network in the RRC_INACTIVE state. Prior to Rel-16, the RRC_INACTIVE state did not support data transmission. Therefore, the UE must resume the connection (i.e. move to RRC_CONNECTED state) for any DL (MT) and UL (MO) data. The connection setup and subsequent release to the INACTIVE state occurs for every data transmission, no matter how small and how frequent the data packets are. This results in unnecessary power consumption and signaling overhead.

[0007] To enable resource-efficient multicast / broadcast services (MBS) delivery, 3GPP developed NR broadcast / multicast in Rel-17, aiming to enable universal MBS services over the 5G system (5GS). Identified use cases that may benefit from this capability include public safety and mission-critical, V2X applications, IPTV, real-time video, software delivery for wireless and IoT applications, etc. Two delivery modes have been agreed for Rel-17 MBS, one delivery mode 1 (for multicast only) capable of handling higher QoS services, and the other delivery mode 2 (for broadcast only) focusing on lower QoS services. Given that Rel-17 MBS already provides the basic functionality to support MBS services, the overall main goal of Rel-18 should be to achieve better deployment of MBS, such as improving resource efficiency and capacity based on Rel-17 MBS.

[0008] In Rel-17, RAN specifies multicast only for UEs in RRC_CONNECTED state, for example, which may not fully meet the requirements of mission-critical services, especially for cells with a large number of UEs. In addition, it is not energy-efficient to always keep UEs in RRC_CONNECTED state. Therefore, it is very important to support multicast for UEs in RRC_INACTIVE.

[0009] In the RANP#94 meeting, the following R18 WID was approved (RP-213568). -Specify support for multicast reception for UEs in RRC_INACTIVE state [RAN2, RAN3] ο PTM configuration for UEs receiving multicast in RRC_INACTIVE state [RAN2] o Study the impact of mobility and state transitions on UEs receiving multicast in RRC_INACTIVE. (Seamless / lossless mobility is not required) [RAN2, RAN3] - Specify Uu signalling enhancements to allow UE to use shared processing for MBS broadcast and unicast reception, i.e. including UE capabilities and related assistance information reporting on simultaneous unicast reception and MBS broadcast reception from the same or different operators in RRC_CONNECTED [RAN2] - Study and, if necessary, specify enhancements to improve resource efficiency of MBS reception in RAN sharing scenarios [RAN3] NOTE: To achieve the above objectives, collaboration with SA2 is expected when appropriate.

[0010] In R17, UEs interested in receiving multicast services must remain connected while receiving the services and be able to use Hybrid Automatic Repeat Request (HARQ) to ensure reliability. However, in R18, UEs interested in receiving multicast services are allowed to remain in an inactive state while receiving the services. In the inactive state, HARQ feedback cannot be sent to the gNB, so HARQ is allowed to be used. Therefore, in this case, reliability cannot be guaranteed, especially for multicast services with high reliability requirements.

[0011] Therefore, it is necessary to develop a mechanism to solve the above problems. Technical Solution

[0012] The purpose of the present disclosure is to provide a wireless communication method and related equipment, which are used to improve the reliability of multicast service transmission in an inactive state.

[0013] In a first aspect, an embodiment of the present application provides a wireless communication method performed by a user equipment UE in a network, the method comprising: receiving a multicast service in an inactive state; triggering a small data transmission SDT process to send a hybrid automatic repeat request HARQ feedback for the multicast service during the inactive state.

[0014] In a second aspect, an embodiment of the present application provides a wireless communication method performed by a user equipment UE in a network, the method comprising: receiving a multicast service in an inactive state; switching to a connected state, and sending a hybrid automatic repeat request HARQ feedback of the multicast service in the connected state.

[0015] In a third aspect, an embodiment of the present application provides a wireless communication method performed by a user equipment UE in a network, the method comprising: receiving a first multicast data packet having one or more repetitions in an inactive state, but not sending any hybrid automatic repeat request HARQ feedback for the first multicast data packet or one or more repetitions of the first multicast data packet in the inactive state.

[0016] In a fourth aspect, an embodiment of the present application provides a wireless communication method performed by a base station BS in a network, the method comprising: transmitting a multicast service to a user equipment UE in an inactive state; receiving a hybrid automatic repeat request HARQ feedback of the multicast service, wherein the HARQ feedback is transmitted from the UE in the inactive state using a small data transmission SDT process.

[0017] In a fifth aspect, an embodiment of the present application provides a wireless communication method, which is performed by a base station BS in a network, and the method includes: transmitting a multicast service to a user equipment UE in an inactive state; when the UE switches from the inactive state to a connected state, receiving a hybrid automatic repeat request HARQ feedback of the multicast service from the UE.

[0018] In a sixth aspect, an embodiment of the present application provides a wireless communication method performed by a base station BS in a network, the method comprising: transmitting a first multicast data packet having one or more repetitions from a user equipment UE in an inactive state, without receiving any hybrid automatic repeat request HARQ feedback for the first multicast data packet or one or more repetitions of the first multicast data packet from the UE in the inactive state.

[0019] In the seventh aspect, an embodiment of the present application provides a UE, comprising a processor and a transmitter, wherein the processor is configured to call and run program instructions stored in a memory to cooperate with the transmitter to execute any one of the methods of the first, second or third aspects.

[0020] In an eighth aspect, an embodiment of the present application provides a BS, comprising a processor and a transmitter, wherein the processor is configured to call and run program instructions stored in a memory to cooperate with the transmitter to execute any method of the fourth, fifth or sixth aspect.

[0021] In a ninth aspect, an embodiment of the present application provides a computer-readable storage medium for storing a computer program, enabling a computer to execute any one of the methods of the first to sixth aspects.

[0022] In a tenth aspect, an embodiment of the present application provides a computer program product comprising computer program instructions that enable a computer to execute the method of any one of the first to sixth aspects.

[0023] In an eleventh aspect, an embodiment of the present application provides a computer program which, when run on a computer, enables the computer to execute any one of the methods in the first to sixth aspects.

[0024] The non-transitory computer readable medium may include at least one of the following group: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a read-only memory, a programmable read-only memory, an erasable programmable read-only memory, an EPROM, an electrically erasable programmable read-only memory, and a flash memory. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 A block diagram of an embodiment of the present application is shown.

[0027] Figure 2 A flow chart of a wireless communication method according to a first embodiment of the present application is shown.

[0028] Figure 3 A flow chart of enabling HARQ feedback in an inactive state according to an embodiment of the present application is shown.

[0029] Figure 4A A flow chart of transmitting HARQ feedback for multicast services in a four-step RA-SDT according to an embodiment of the present application is shown.

[0030] Figure 4B A flow chart of a two-step RA-SDT for transmitting HARQ feedback for a multicast service according to an embodiment of the present application is shown.

[0031] Figure 4C A flow chart of transmitting HARQ feedback for multicast services in CG-SDT according to an embodiment of the present application is shown.

[0032] Figure 5A A flow chart of transmitting HARQ feedback in subsequent transmission of a multicast service according to a four-step RA-SDT according to an embodiment of the present application is shown.

[0033] Figure 5B A flow chart of transmitting HARQ feedback in subsequent transmissions in a two-step RA-SDT for multicast services according to an embodiment of the present application is shown.

[0034] Figure 5C A flow chart showing the transmission of HARQ feedback in subsequent transmission of a multicast service by CG-SDT according to an embodiment of the present application.

[0035] Figure 6 A flow chart of a wireless communication method according to a second embodiment of the present application is shown.

[0036] Figure 7A flow chart of transmitting HARQ feedback in a connected state for a multicast service according to an embodiment of the present application is shown.

[0037] Figure 8 A flow chart of a wireless communication method according to a third embodiment of the present application is shown.

[0038] Fig. 9 A flow chart of receiving a multicast data packet with duplicate items without transmitting HARQ feedback in an inactive state according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0039] The embodiments of the present invention describe technical matters, structural features, implementation purposes and effects in detail with reference to the accompanying drawings. Specifically, the terms in the embodiments of the present invention are only used for the purpose of describing specific embodiments, rather than limiting the disclosure.

[0040] Figure 1 In some embodiments, one or more user equipments (UEs) and a base station (e.g., gNB or eNB) 20 for wireless communication provided by a communication network system 30 according to an embodiment of the present application are shown. The communication network system 30 includes the one or more UEs 10 and the base station 20. The one or more UEs 10 may include a memory 12, a transceiver 13, and a processor 11 coupled to the memory 12 and the transceiver 13. The base station 20 may include a memory 22, a transceiver 23, and a processor 21 coupled to the memory 22 and the transceiver 23. The processor 11 or 21 may be configured to implement the proposed functions, procedures, and / or methods described in this specification. The wireless interface protocol layer may be implemented in the processor 11 or 21. The memory 12 or 22 is operably coupled to the processor 11 or 21 and stores various information to operate the processor 11 or 21. The transceiver 13 or 23 is operably coupled to the processor 11 or 21, and the transceiver 13 or 23 sends and / or receives wireless signals.

[0041] The processor 11 or 21 may include an application specific integrated circuit (ASIC), other chipsets, logic circuits and / or data processing devices. The memory 12 or 22 may include a read-only memory (ROM), a random access memory (RAM), flash memory, a memory card, a storage medium and / or other storage devices. The transceiver 13 or 23 may include a baseband circuit for processing radio frequency signals. When these embodiments are implemented in software, the techniques described herein may be implemented by modules (e.g., programs, functions, etc.) that perform the functions described herein. These modules may be stored in the memory 12 or 22 and executed by the processor 11 or 21. The memory 12 or 22 may be implemented within the processor 11 or 21, or implemented outside the processor 11 or 21, in which case those external components may be communicatively coupled to the processor 11 or 21 in various ways known in the art.

[0042] Figure 2 FIG. 1 is a flow chart of a wireless communication method 100 according to a first embodiment of the present application. Figure 1 and Figure 2 , the method 100 includes the following contents. In step 110, the UE 10 receives a multicast service from the base station 20 when it is in an inactive state (e.g., RRC_INACTIVE state). In step 120, the UE 10 sends a hybrid automatic repeat request (HARQ) feedback of the multicast service to the base station 20. The UE 10 triggers a small data transmission (SDT) process during the inactive state to send the HARQ feedback. The HARQ feedback is transmitted from the UE to the base station 20 during the SDT process. Using this method, the reliability of the multicast service transmission in the inactive state can be improved.

[0043] In an embodiment, the method further comprises: receiving an indication, the indication being an indication of enabling HARQ feedback for the multicast service. HARQ feedback is allowed, and HARQ feedback may also be enabled / disabled. Figure 3 , Figure 3 A flowchart is shown for enabling HARQ feedback in an inactive state according to an embodiment of the present application. When the UE is in an inactive state (e.g., RRC_INACTIVE state) and receives a multicast service (steps 1 and 2), the base station (e.g., gNB) may send an indication to the UE to indicate that HARQ feedback has been enabled and that the UE is required to send an acknowledgment (ACK / NACK) of receiving the multicast service when in an inactive state (step 4). After receiving the indication, the UE may send HARQ feedback in the SDT process to the base station in an inactive state. When the quality of service (QoS) of the multicast service is higher than a threshold, HARQ feedback for the multicast service may be enabled. When this condition is met, the base station may decide to send a notification (step 3). When the QoS requirements for the multicast service are high, HARQ feedback may be enabled to ensure the reliability of the multicast service transmission. When the QoS requirements for the multicast service are low, HARQ feedback may be disabled to improve resource efficiency.

[0044] In one embodiment, the SDT process is a four-step Random Access (RA)-SDT process, and the HARQ feedback is performed on MSG3. The UE can transmit the HARQ feedback of the multicast service in the four-step RA-SDT process. Please refer to Figure 4A , Figure 4AA flowchart is shown of an embodiment of the present application for transmitting HARQ feedback for a multicast service in a four-step RA-SDT. When the UE is in an inactive state (e.g., RRC_INACTIVE state) and receives a multicast service (steps 1 and 2), if HARQ feedback is enabled (e.g., a multicast service requiring high QoS), the UE can trigger a four-step RA-SDT process to feed back the ACK / NACK of the multicast service to the base station (step 3). During the four-step RA-SDT process, the UE sends the preamble in MSG1 to the base station (step 4), and the base station transmits a random access response (RAR) message in MSG2 in response to the preamble (step 5). Thereafter, a radio resource control (RRC) recovery request is transmitted to the base station via MSG 3. HARQ feedback for the multicast service can be performed on MSG3 (step 6). After receiving the RRC recovery request, the base station sends MSG 4 to the UE to resolve contention issues (step 7). The UE may terminate the SDT procedure (steps 8 and 9) upon receiving the suspended RRC release configuration sent by the gNB and remain in the inactive state (step 10).

[0045] In one embodiment, the SDT process is a two-step random access (RA)-SDT process, and the HARQ feedback can be carried on the MSGA. The UE can transmit the HARQ feedback of the multicast service in the two-step RA-SDT process. Please refer to Figure 4B , Figure 4B A flowchart is shown of an embodiment of the present application using two-step RA-SDT to transmit HARQ feedback for a multicast service. When the UE is in an inactive state (e.g., RRC_INACTIVE state) and receives a multicast service (steps 1 and 2), if HARQ feedback is enabled (e.g., a multicast service requiring high QoS), the UE can trigger a two-step RA-SDT process to feed back the ACK / NACK of the multicast service to the base station (step 3). In the two-step RA-SDT process, the UE sends a preamble and a radio resource control (RRC) recovery request in MSGA to the base station, where the HARQ feedback of the multicast service can be carried on MSGA (step 4), and the base station transmits a random access response (RAR) message in MSGB in response to the preamble, and sends the MSGB to the UE after receiving the RRC recovery to resolve the contention request (step 5). The UE can end the SDT process (steps 6 and 7) when receiving the suspended RRC release configuration sent by the gNB, and still remain in an inactive state (step 8).

[0046] In one embodiment, the SDT process is a Configured Grant (CG)-SDT process, and the HARQ feedback is transmitted on the CG resources. The UE can transmit the HARQ feedback of the multicast service during the CG-SDT process. Figure 4C , Figure 4C A flowchart of an embodiment of the present application for transmitting HARQ feedback for multicast services in CG-SDT is depicted. When the UE is in an inactive state (e.g., RRC_INACTIVE state) and receives a multicast service (steps 1 and 2), if HARQ feedback is enabled (e.g., a multicast service requiring high QoS), the UE can trigger the CG-SDT process and feed back ACK / NACK to the base station for the multicast service (step 3). During the CG-SDT process, the UE sends a radio resource control (RRC) recovery request to the base station, and the HARQ feedback of the multicast service can be transmitted on the CG resources (step 4). The UE can end the SDT process (steps 5 and 6) when it receives the suspended RRC release configuration sent by the gNB, and still remain in an inactive state (step 7).

[0047] The high-level procedure for selecting between SDT and non-SDT procedures when data arrives only for SDT-enabled data radio bearers (DRBs) / signaling radio bearers (SRBs) is as follows: If the CG-SDT conditions are met: The UE selects CG-SDT. The UE starts the CG-SDT procedure. Otherwise, if the RA-SDT conditions are met: The UE selects RA-SDT. The UE starts the RA-SDT procedure. Otherwise: The UE starts the non-SDT procedure. The CG-SDT criteria are considered to be met if all of the following conditions are met: 1) The amount of available data is less than or equal to the data amount threshold; 2) The reference signal received power (RSRP) is greater than or equal to the configured threshold; 3) The CG-SDT resources are configured and valid on the selected uplink (UL) operator. The RA-SDT criteria are considered to be met if all of the following conditions are met: 1) the amount of available data is less than or equal to the data amount threshold; 2) the reference signal received power (RSRP) is greater than or equal to the configured threshold; 3) four-step RA-SDT resources are configured on the selected UL operator and the conditions for selecting four-step RASDT are met; or two-step RA-SDT resources are configured on the selected UL operator and the conditions for selecting two-step RASDT are met.

[0048] In the current 3GPP specification (R17), subsequent transmissions are allowed in the SDT process. Here, after the first ACK / NACK is transmitted, subsequent ACK / NACKs of the multicast service received in the inactive state may also be transmitted in the SDT process.

[0049] In one embodiment, the HARQ feedback for the multicast service may be transmitted via a subsequent transmission in the four-step RA-SDT process. The HARQ feedback for the multicast service may be the first HARQ feedback in the four-step RA-SDT process, or may be a subsequent HARQ feedback in the four-step RA-SDT process. Figure 5A , Figure 5A A flow chart showing a four-step RA-SDT for transmitting HARQ feedback in subsequent transmissions of a multicast service according to an embodiment of the present application. After the four-step RA, subsequent transmissions will be performed on the four-step RA-SDT resources. The HARQ feedback for the multicast service may be a subsequent HARQ feedback in the four-step RA-SDT process (step 8). In the four-step RA-SDT process, the subsequent HARQ feedback is sent after the first HARQ feedback.

[0050] In one embodiment, the HARQ feedback for the multicast service may be transmitted via a subsequent transmission in the two-step RA-SDT process. The HARQ feedback for the multicast service may be the first HARQ feedback in the two-step RA-SDT process or a subsequent HARQ feedback in the two-step RA-SDT process. Figure 5B , Figure 5B A flow chart showing a two-step RA-SDT for transmitting HARQ feedback in subsequent transmissions of a multicast service according to an embodiment of the present application. After the two-step RA, subsequent transmissions will be performed on the two-step RA-SDT resources. The HARQ feedback for the multicast service may be a subsequent HARQ feedback in the two-step RA-SDT process (step 6). In the two-step RA-SDT process, the subsequent HARQ feedback is sent after the first HARQ feedback.

[0051] In one embodiment, the HARQ feedback for the multicast service may be transmitted through subsequent transmissions during the CG-SDT process. The HARQ feedback for the multicast service may be the first HARQ feedback during the CG-SDT process or a subsequent HARQ feedback during the CG-SDT process. Figure 5C , Figure 5C A flowchart showing the transmission of HARQ feedback in subsequent transmissions of a multicast service by CG-SDT according to an embodiment of the present application. After the first transmission on the CG resource, subsequent transmissions will also be made on the CG resource. The HARQ feedback for the multicast service may be a subsequent HARQ feedback in the CG-SDT process (step 5). In the CG-SDT process, subsequent HARQ feedback will be sent after the first HARQ feedback.

[0052] In one embodiment, the method further comprises: when the timer expires or the counter reaches a maximum value, stopping sending subsequent HARQ feedback. FIG. 5A to FIG. 5C, the base station may set / configure a timer or counter for subsequent transmission during the SDT process (e.g., CG-SDT, four-step RA-SDT, 2-step RA-SDT). When the timer expires or the counter reaches the maximum value, the UE may stop sending subsequent HARQ feedback for the multicast service to the base station, and does not allow transmission of ACK / NACK during the SDT process. That is, transmission of subsequent HARQ feedback is allowed only when the timer has not expired or the counter has not reached the maximum value.

[0053] Figure 6 FIG. 2 is a flow chart of a wireless communication method 200 according to a second embodiment of the present application. Figure 1 and Figure 6 , the method 200 includes the following contents. In step 210, the UE 10 receives a multicast service from a base station in an inactive state (e.g., an RRC INACTIVE state). In step 220, the UE 10 transitions from the inactive state to a connected state (e.g., an RRC_Connected state), and then sends a hybrid automatic repeat request (HARQ) feedback for the multicast service during the connected state. That is, when the UE is in the connected state, the base station 20 receives HARQ feedback from the multicast service from the UE. Using this method, the reliability of the multicast service transmission in the inactive state can be improved.

[0054] Please combine Figure 6 and Figure 7 . Figure 7 A flowchart is shown for transmitting HARQ feedback in a connected state for a multicast service according to an embodiment of the present application. When the UE is in an inactive state (e.g., RRC_INACTIVE state) and receives a multicast service (steps 1 and 2), the base station (e.g., gNB) may send an indication to the UE to indicate that HARQ feedback is enabled and that the UE is required to send an acknowledgment (ACK / NACK) for the received multicast service (step 3). If the UE is only allowed to send ACK / NACK in a connected state, the UE needs to enter a connected state first (step 4). The UE sends HARQ feedback for the received multicast service during the connected state (step 5). Then, the base station may deactivate HARQ feedback after receiving the HARQ feedback (step 6). If HARQ feedback does not need to be transmitted, the UE may enter an inactive state again (step 7). The UE may receive the multicast service again in an inactive state (step 8).

[0055] Figure 8 A flowchart of a wireless communication method 300 according to Embodiment 3 of the present application is shown. The above mechanism focuses on using HARQ feedback to ensure reliability. There may be other methods to improve reliability. See Figure 1 and Figure 8, the method 300 includes the following contents. In step 310, the UE 10 receives a first multicast data packet having one or more repetitions from the base station 20 when in an inactive state. In this case, in the inactive state, it is not necessary to send a hybrid automatic repeat request (HARQ) feedback of the first multicast data packet or a HARQ feedback of one or more repetitions of the first multicast data packet from the UE 10 to the base station 20. In some embodiments, the UE 10 may receive a non-repetitive second multicast data packet from the base station 20 in a connected state, and send a HARQ feedback for the second multicast data packet to the base station 20 in the connected state. Using this method, the reliability of the multicast service transmission in the inactive state is ensured by repeatedly transmitting the multicast data packet.

[0056] See also Figure 8 and Fig. 9 . Fig. 9 A flowchart of an embodiment of the present application is shown for receiving a multicast data packet with duplicates in an inactive state without transmitting HARQ feedback. Due to the high QoS requirements of the multicast service, reliability needs to be guaranteed even in the inactive state. When the UE is in an inactive state (e.g., RRC_INACTIVE state) and receives the multicast service (steps 1 and 2), the base station (e.g., gNB) can send the same multicast data packet multiple times (e.g., the gNB has one or more duplicate multicast data packets), and the UE is in an inactive state at this time (step 3). During the inactive state, the multicast data packet is transmitted repeatedly. When the state is converted to a connected state (step 5), a traditional reliability mechanism, such as HARQ feedback, can be used. After receiving multicast data packet N in the connected state (step 6), the UE sends HARQ feedback of multicast data packet N to the base station (step 7). After receiving multicast data packet N+1 in the connected state (step 8), the UE sends HARQ feedback of multicast data packet N+1 to the base station (step 9). During the connected state, the transmission of multicast data packets will not be repeated.

[0057] The commercial benefits of some embodiments are as follows. 1. Solve problems in the prior art 2. Enhance the reliability of multicast service transmission in an inactive state. 3. Provide good communication performance. Some embodiments of the present application are used by 5G-NR chipset suppliers, V2X communication system development suppliers, automobile manufacturers (including cars, trains, trucks, buses, bicycles, motorcycles, helmets, etc.), unmanned vehicles (drones), smartphone manufacturers, public safety communication equipment, AR / VR equipment manufacturers for games, conferences / seminars, and educational purposes. Some embodiments of the present application are a combination of "technology / processes" that can be adopted in 3GPP specifications to create a final product. Some embodiments of the present application can be used in 5G NR unlicensed band communications. Some embodiments of the present application propose technical mechanisms.

[0058] The embodiment of the present application also provides a computer-readable storage medium for storing a computer program. The computer-readable storage medium enables a computer to execute the corresponding process implemented by the UE / BS in each method of the embodiment of the present application. For the sake of brevity, the details are not repeated herein.

[0059] The embodiment of the present application also provides a computer program product, including computer program instructions. The computer program product enables a computer to execute the corresponding process implemented by the UE / BS in each method of the embodiment of the present application. For the sake of brevity, the details are not repeated herein.

[0060] The embodiment of the present application also provides a computer program. The computer program enables a computer to execute the corresponding process implemented by the UE / BS in each method of the embodiment of the present application. For the sake of brevity, the details are not repeated herein.

[0061] Although not shown in detail, any device or apparatus forming part of the network may include at least a processor, a storage unit and a communication interface, wherein the processor unit, the storage unit and the communication interface are configured to perform the method of any aspect of the present invention.

[0062] Those skilled in the art will appreciate that, in conjunction with the embodiments described in the embodiments disclosed in this specification, the units and algorithm steps may be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the functions described for each specific application, but it should not be considered that the implementation is beyond the scope of this application.

[0063] Furthermore, although individually listed, several methods, components or method steps may be implemented by, for example, a single unit or processor. Furthermore, although individual features may be included in different claims, these may advantageously be combined together, and the inclusion in different claims does not imply that a combination of features is not feasible and / or advantageous. Furthermore, the inclusion of a feature in a certain category of claims does not imply a limitation to that category, but rather indicates that the feature is equally applicable to other claim categories where appropriate.

[0064] Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. Furthermore, singular references do not exclude a plurality. Thus references to 'a', 'an', 'first', 'second' etc do not exclude a plurality.

[0065] While the present application has been described in connection with what is considered to be the most practical and preferred embodiments, it is to be understood that the application is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the broadest interpretation of the appended claims.

Claims

1. A wireless communication method, performed by a user equipment UE in a network, the method comprising: Receiving multicast services in an inactive state; and A small data transmission (SDT) process is triggered to send a hybrid automatic repeat request (HARQ) feedback for the multicast service during the inactive state.

2. The method according to claim 1, characterized in that Also includes: An indication is received, where the indication is used to indicate enabling HARQ feedback of the multicast service.

3. The method according to claim 2, characterized in that When the quality of service QoS of the multicast service is higher than a threshold, the HARQ feedback of the multicast service is enabled.

4. The method according to claim 1, characterized in that: The SDT process is a configuration authorized CG-SDT process, and the HARQ feedback is transmitted on CG resources.

5. The method according to claim 1, characterized in that The SDT process is a four-step random access RA-SDT process, and the HARQ feedback is performed on MSG3.

6. The method according to claim 1, characterized in that The SDT process is a two-step random access RA-SDT process, and the HARQ feedback is performed on the MSGA.

7. The method according to claim 1, characterized in that The HARQ feedback for the multicast service includes a first HARQ feedback and a subsequent HARQ feedback after the first HARQ feedback, wherein during the SDT process, the subsequent HARQ feedback is sent after the first HARQ feedback.

8. The method according to claim 7, characterized in that Also includes: When the timer expires or the counter reaches a maximum value, the subsequent HARQ feedback is stopped from being sent.

9. The method according to claim 7, characterized in that: The SDT process is a CG-SDT process, a four-step RA-SDT process or a two-step RA-SDT process.

10. A wireless communication method, performed by a user equipment UE in a network, the method comprising: Receiving multicast services in an inactive state; and The state is converted to a connected state, and a hybrid automatic repeat request HARQ feedback of the multicast service is sent in the connected state.

11. A wireless communication method, performed by a user equipment UE in a network, the method comprising: A first multicast data packet having one or more repetitions is received in an inactive state, but no hybrid automatic repeat request (HARQ) feedback is sent for the first multicast data packet or the one or more repetitions of the first multicast data packet in the inactive state.

12. The method according to claim 11, characterized in that Also includes: receiving a non-duplicate second multicast data packet in the connection state; and Sending HARQ feedback of the second multicast data packet in the connected state.

13. A wireless communication method, performed by a base station BS in a network, the method comprising: transmitting a multicast service to a user equipment UE in an inactive state; and A hybrid automatic repeat request (HARQ) feedback for the multicast service is received, wherein the HARQ feedback is transmitted from the UE in the inactive state in a small data transmission (SDT) process.

14. The method according to claim 13, further comprising: An indication is transmitted to the UE, indicating that the HARQ feedback for the multicast service is enabled.

15. The method according to claim 14, characterized in that When the quality of service QoS of the multicast service is higher than a threshold, the HARQ feedback of the multicast service is enabled.

16. The method according to claim 13, characterized in that The SDT process is a configuration authorized CG-SDT process, and the HARQ feedback is transmitted on CG resources.

17. The method according to claim 13, characterized in that The SDT process is a four-step random access RA-SDT process, and the HARQ feedback is performed on MSG3.

18. The method according to claim 13, characterized in that The SDT process is a two-step random access RA-SDT process, and the HARQ feedback is performed on the MSGA.

19. The method according to claim 13, characterized in that The HARQ feedback for the multicast service includes a first HARQ feedback and a subsequent HARQ feedback after the first HARQ feedback, and in the SDT process, the subsequent HARQ feedback is sent after the first HARQ feedback.

20. The method according to claim 19, characterized in that Also includes: When the timer expires or the counter reaches a maximum value, the UE stops sending the subsequent HARQ feedback.

21. The method according to claim 19, characterized in that The SDT process is a CG-SDT process, a four-step RA-SDT process, or a two-step RA-SDT process.

22. A wireless communication method, performed by a base station BS in a network, the method comprising: transmitting a multicast service to a user equipment UE in an inactive state; and When the UE transitions from the inactive state to the connected state, a hybrid automatic repeat request (HARQ) feedback of the multicast service is received from the UE.

23. A wireless communication method, performed by a base station BS in a network, the method comprising: A first multicast data packet having one or more repetitions is transmitted from a user equipment (UE) in an inactive state without receiving any hybrid automatic repeat request (HARQ) feedback for the first multicast data packet or the one or more repetitions of the first multicast data packet from the UE in the inactive state.

24. The method according to claim 23, characterized in that Also includes: sending a second multicast data packet to the UE without repeating in a connected state; and HARQ feedback of the second multicast data packet received from the UE in the connected state.

25. A user equipment UE, comprising a processor and a transceiver, wherein: The processor is configured to call and run program instructions stored in the memory to cooperate with the transceiver to perform the method according to any one of claims 1 to 9.

26. A base station BS, comprising a processor and a transceiver, wherein: The processor is configured to call and execute program instructions stored in the memory to cooperate with the transceiver to perform the method according to any one of claims 13 to 21.

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