Method and apparatus for DRX operation for multicast and broadcast services

Abstract

An embodiment of the present application is directed to a method and apparatus for DRX operation for MBS. The method is implemented by a UE. The UE is configured for MBS DRX operation. The method may include monitoring a point-to-multipoint (PTM) initial transmission associated with the MBS from a base station during an active time period for the MBS DRX operation, the PTM initial transmission being further associated with a first identifier, and monitoring a PTM retransmission associated with the MBS from the base station, the PTM retransmission being further associated with the first identifier, or a second identifier, or both the first identifier and the second identifier.

Description

Technical Field

[0001] Embodiments of the present application generally relate to wireless communication technologies, and in particular, to methods and apparatuses for discontinuous reception (DRX) operations for multicast and broadcast services (MBS).

Background Art

[0002] In new radio (NR) Rel-17, MBS is planned to focus on small area hybrid mode multicast (also called target A in TR 23.757). Target A is about enabling general MBS services across 5G systems (5GS) and identified use cases that can benefit from this feature. These use cases include, but are not limited to, public safety and mission critical, vehicle-to-everything (V2X) applications, transparent Internet Protocol version 4 (IPv4) / Internet Protocol version 6 (IPv6) multicast delivery, Internet Protocol television (IPTV), wireless software delivery, group communication, and Internet of Things (IoT) applications. NR MBS will support multicast services for user equipment (UE) in the RRC_CONNECTED state.

[0003] In NR MBS, there are two modes for data transmission, such as point-to-multipoint (PTM) transmission and point-to-point (PTP) transmission. For high reliability multicast services, hybrid automatic repeat request (HARQ) and retransmission will be supported for NR MBS. While the initial transmission may be provided by the PTM method, the HARQ retransmission may be provided by the PTP method.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

[0005] Therefore, we need to consider how to achieve effective power savings for NR MBS for UEs in highly reliable multicast services that support HARQ and retransmission. [Means for solving the problem]

[0006] Embodiments of this application provide a method and apparatus for DRX operation for MBS.

[0007] Some embodiments of this application provide a method implemented by a user equipment (UE), the UE comprising an MBS DRX operation. The method may include the steps of: monitoring a point-to-multipoint (PTM) initial transmission associated with an MBS from a base station during an activity time period for an MBS DRX operation, wherein the PTM initial transmission is further associated with a first identifier; and monitoring a PTM retransmission associated with an MBS from a base station, wherein the PTM retransmission is further associated with a first identifier, or a second identifier, or both the first and second identifiers.

[0008] Some other embodiments of this application provide methods implemented by BS. These methods may include the step of configuring values ​​for at least one timer for point-to-multipoint (PTM) initial transmission, PTM retransmission, and point-to-point (PTP) transmission of multicast and broadcast service (MBS) intermittent receive (DRX) operations to a UE.

[0009] Some other embodiments of this application provide an apparatus. The apparatus may include a processor and a wireless transceiver coupled to the processor. The processor is configured to carry out the above method with the wireless transceiver.

[0010] Embodiments of this application can achieve effective power savings for NR MBS for UEs in highly reliable multicast services that support HARQ and retransmission.

[0011] To describe the methods by which the advantages and features of this application can be obtained, the description of this application is expressed with reference to specific embodiments of this application illustrated in the accompanying drawings. These drawings depict merely illustrative embodiments of this application and should not be considered to limit its scope. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram illustrating an exemplary wireless communication system 100 according to several embodiments of this application. [Figure 2] This is a flowchart illustrating a method for DRX operation for MBS according to several embodiments of this application. [Figure 3] This is a schematic diagram illustrating configurations for MBS-dedicated DRX operation and unicast DRX operation according to several embodiments of this application. [Figure 4] This figure illustrates a method for configuring DRX operation for MBS according to an embodiment of the present application. [Figure 5] This figure illustrates a method for configuring DRX operation for MBS according to another embodiment of the present application. [Figure 6] This figure illustrates a method for configuring DRX operation for MBS according to another embodiment of the present application. [Figure 7] This figure illustrates an apparatus according to several embodiments of this application. [Figure 8]This figure illustrates another apparatus according to some other embodiments of the present application. [Modes for carrying out the invention]

[0013] The detailed description in the attached drawings is intended to describe a currently preferred embodiment of this application and is not intended to represent the only form in which this application can be carried out. It should be understood that the same or equivalent functions can be achieved by different embodiments intended to be covered within the spirit and scope of this application.

[0014] Herein, references are made in detail to several embodiments of this application, the examples of which are illustrated in the accompanying drawings. For ease of understanding, the embodiments are provided under specific network architectures and new service scenarios, such as 3GPP® 5G and 3GPP® LTE Release 8. Those skilled in the art will know very well that as network architectures and new service scenarios evolve, the embodiments of this application will still be applicable to similar technical problems.

[0015] Figure 1 is a schematic diagram illustrating an exemplary wireless communication system 100 according to an embodiment of this application.

[0016] As shown in Figure 1, the wireless communication system 100 includes at least one BS101 and at least one UE102. In particular, for illustrative purposes, the wireless communication system 100 includes one BS101 and two UE102s (e.g., UE102a and UE102b). Although a specific number of BS101s and UE102s are depicted in Figure 1, it is intended that any number of BS101s and UE102s can be included in the wireless communication system 100.

[0017] BS101 can be referred to as an access point, access terminal, base, macrocell, Node B, evolved Node B (eNB), gNB, home Node B, relay node, or device, or described using other terms used in the art. BS101 is generally a part of a radio access network that can include a controller communicatively coupled to BS101.

[0018] UE102 can include computing devices such as desktop computers, laptop computers, personal digital assistants (PDAs), tablet computers, smart televisions (e.g., televisions connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), in-vehicle computers, network devices (e.g., routers, switches, and modems), and the like. According to embodiments of the present application, examples of UE102 include mobile wireless communication devices, smartphones, cellular phones, flip phones, devices having a subscriber identity module, personal computers, selectable call receivers, or any other device capable of transmitting and receiving communication signals over a wireless network. In some embodiments, examples of UE102 include wearable devices such as smart watches, fitness bands, and optical head-mounted displays. Further, UE102 can be referred to as a subscriber unit, mobile body, mobile station, user, terminal, mobile terminal, wireless terminal, fixed terminal, subscriber station, user terminal, or device, or described using other terms used in the art.

[0019] Wireless communication system 100 is compatible with any type of network capable of transmitting and receiving wireless communication signals. For example, wireless communication system 100 is compatible with a wireless communication network, a cellular phone network, a time division multiple access (TDMA)-based network, a code division multiple access (CDMA)-based network, an orthogonal frequency division multiple access (OFDMA)-based network, an LTE network, a 3GPP (registered trademark)-based network, a 3GPP (registered trademark) 5G network, a satellite communication network, a high altitude platform network, and / or other communication networks.

[0020] In NR MBS, there are two modes for data transmission, such as PTM transmission and PTP transmission.

[0021] In PTM transmission, the BS can distribute a single copy of the MBS data packet to a set of UEs. That is, the BS uses a group common physical downlink control channel (PDCCH) having a cyclic redundancy check (CRC) scrambled by a group common radio network temporary identifier (RNTI) (e.g., group RNTI (G-RNTI)) to schedule a group common physical downlink shared channel (PDSCH) scrambled with the same group common RNTI.

[0022] In PTP transmission, the BS can distribute separate copies of the MBS data packet to UEs individually. That is, the BS uses a UE-specific PDCCH having a cyclic redundancy check (CRC) scrambled by a UE-specific RNTI (e.g., cell radio network temporary identifier (C-RNTI)) to schedule a UE-specific PDSCH scrambled with the same UE-specific RNTI.

[0023] For example, as shown in Figure 1, BS101 can send a single copy of an MBS data packet to UE102a and UE102b via PTM transmission. In another example, BS101 can send separate copies of an MBS data packet to UE102a and UE102b via PTP transmission.

[0024] As discussed above, in highly reliable multicast services, HARQ and retransmission will be supported for NR MBS. Initial transmission may be provided using the PTM method, while HARQ retransmission may be provided using the PTP method.

[0025] DRX is a key feature for power saving in the UE. DRX allows the UE to stop monitoring the PDCCH during periods of no data activity, thereby saving power. In LTE, there is one DRX operation for unicast traffic (or unicast transmission) and one DRX operation for each G-RNTI / single-cell multicast traffic channel (SC-MTSC) for single-cell point-to-multipoint (SC-PTM). The difference between the DRX operation for unicast transmission and the DRX operation for SC-PTM is that the latter is suitable for both RRC_IDLE and RRC_CONNECTED, and the latter lacks the DRX short-cycle function as well as the functions related to the HARQ timer and retransmission timer. Existing HARQ and retransmission-related timers include drx-HARQ-RTT-TimerDL and drx-RetransmissionTimerDL. Each of the two timers is per downlink (DL) HARQ process other than the broadcast process. drx-HARQ-RTT-TimerDL can be used to indicate the shortest duration before DL allocation for HARQ retransmission. drx-RetransmissionTimerDL can be used to indicate the longest duration until DL retransmission is received.

[0026] Generally, RRC controls DRX operation by configuring the following parameters. - drx-onDurationTimer: Duration at the start of the DRX cycle - drx-SlotOffset: Delay before starting drx-onDurationTimer - drx-InactivityTimer: Duration after the occurrence of PDCCH. Here, PDCCH indicates a new UL or DL ​​transmission for a MAC entity. - drx-RetransmissionTimerDL (per DL HARQ process other than the broadcast process): Maximum duration until DL retransmission is received. - drx-RetransmissionTimerUL (per UL HARQ process): Maximum duration until permission for UL retransmission is received. - drx-LongCycleStartOffset: Defines the subframe in which ultrashort DRX cycles begin, along with drx-StartOffset. - drx-ShortCycle (optional): Short DRX cycle - drx-ShortCycleTimer (optional): Duration for which the UE continues to perform short DRX cycles. - drx-HARQ-RTT-TimerDL (DL per HARQ process other than broadcast process): DL allocation for HARQ retransmission is the shortest previous duration expected by the MAC entity. - drx-HARQ-RTT-TimerUL(per UL HARQ process): The shortest previous duration before UL HARQ retransmission permission was expected by the MAC entity.

[0027] Those skilled in the art should understand that the parameters above are merely some existing parameters for DRX operation, and that their description is used solely to facilitate the understanding of readers familiar with existing DRX operation, and that they cannot be used to limit this application.

[0028] NR MBS will have some support for HARQ, therefore it is not possible to copy the LTE SC-PTM solution. Thus, the following issues will be considered. (1) The first question regarding DRX support for NR MBS is whether the existing DRX operation is sufficient, or whether a separate DRX operation needs to be introduced for the MBS for monitoring G-RNTI, and (2) In NR MBS, initial transmission is scheduled by a common PDCCH scrambled by G-RNTI using the PTM method, while retransmission can be scheduled by a dedicated PDCCH scrambled by C-RNTI using the PTP method. In this way, the method of implementing the DRX timer related to retransmission is addressed.

[0029] By considering the above issues, the following embodiments of this application can achieve effective power savings for NR MBS for UEs in highly reliable multicast services supporting HARQ and retransmission. Further details of the embodiments of this application are described in the following text in conjunction with the accompanying drawings.

[0030] Figure 2 is a flowchart illustrating a method for DRX operation for MBS according to several embodiments of this application. The method illustrated in Figure 2 can be implemented by a UE (e.g., UE102a and UE102b as shown in Figure 1). The UE can consist of an MBS DRX operation (or a DRX operation specifically for MBS).

[0031] Figure 3 is a schematic diagram illustrating MBS-dedicated DRX operation and unicast DRX operation (or the older DRX operation, also called unicast DRX operation). As shown in Figure 3, the DRX cycle for MBS-dedicated DRX operation may differ from (e.g., be longer) that of unicast DRX operation, and the on-duration for MBS-dedicated DRX operation may also differ from (e.g., be longer) that of unicast DRX operation. This is merely an example, and it should be understood that in some cases, the DRX cycle for MBS-dedicated DRX operation may be shorter than that of unicast DRX operation, and therefore shorter than the on-duration.

[0032] In embodiments of this application, PTM transmission and PTP transmission can be used for MBS. PTM transmission may include PTM initial transmission and PTM retransmission. PTM retransmission may include PTM retransmission via PTP and PTM retransmission via PTM.

[0033] In the initial PTM transmission, the BS delivers a single copy of the MBS data packet to a set of UEs. That is, the BS uses a group-common PDCCH with a group-common CRC that is scrambled by the group-common RNTI to schedule a group-common PDSCH that is scrambled by the same group-common RNTI.

[0034] In PTM retransmission via PTP, HARQ retransmission is performed using a specific PTP transmission method to a particular UE for the initial PTM transmission.

[0035] In PTM retransmission via PTM, HARQ retransmission is performed using the same method as PTM transmission to a single group of UEs.

[0036] In PTP transmission, the BS can deliver separate copies of the MBS data packets individually to the UE. That is, the BS uses a UE-dedicated PDCCH with a CRC that is scrambled by a UE-dedicated RNTI (e.g., C-RNTI) to schedule a UE-dedicated PDSCH that is scrambled by the same UE-dedicated RNTI.

[0037] During MBS transmissions, multicast radio bearer (MRB) transmissions can be performed. For example, the common PDCP layer in the BS can be used for MRBs, so that the BS can deliver a single copy of MBS data packets to a pair of UEs in PTM transmissions, and the BS can deliver separate copies of MBS data packets to individual UEs in PTP transmissions. In contrast to MBS, unicast data radio bearers (DRBs) are for unicast transmissions.

[0038] In some embodiments of this application, during the activity timer period, the UE can perform operations as shown in Figure 2.

[0039] Prior to the operation shown in Figure 2, the BS can configure values ​​for at least one timer for the initial PTM transmission, PTM retransmission, and PTP transmission of the MBS DRX operation, or at least one timer for the unicast transmission to the UE.

[0040] The timers for MBS DRX operation may include one or more of the following, which will be described in detail with respect to specific embodiments: an MBS DRX on-duration timer, an MBS DRX inactivity timer, an MBS DRX retransmission timer, and an MBS DRX HARQ RTT timer.

[0041] As shown in Figure 2, in operation 201, the UE can monitor the initial PTM transmission associated with the MBS from the BS, and the initial PTM transmission is further associated with a first identifier. In operation 202, the UE can monitor the retransmission of a PTM associated with the MBS from the BS, and the retransmission is further associated with a first identifier, or a second identifier, or both the first and second identifiers. For example, the first identifier is G-RNTI and the second identifier is the UE's C-RNTI. The first and second identifiers may be other stored identifiers in the NR network or LTE network. The following description will describe operations 201 and 202 along with several specific embodiments.

[0042] Figure 4 illustrates a method for configuring DRX operation for MBS according to an embodiment of this application.

[0043] As shown in Figure 4, (1) can represent a PTM transmission including an initial PTM transmission and / or a PTM retransmission via PTM, (2) can represent a PTM retransmission via PTP, (3) can represent a PTP transmission, and (4) can represent a unicast transmission.

[0044] In this embodiment, the MBS-dedicated DRX operation is configured for PTM initial transmission (1), PTM retransmission via PTP (2), and PTM retransmission via PTM (1), while the unicast DRX operation is used for PTP transmission (3) (i.e., both initial transmission and retransmission across PTP transmission) and unicast transmission (4).

[0045] In this embodiment, the MBS-dedicated DRX operation may be per G-RNTI or per MBS session. Furthermore, the HARQ retransmission-related timers (e.g., the MBS DRX retransmission timer and the MBS DRX HARQ RTT timer) are also MBS-dedicated. For example, the HARQ retransmission-related timer may be per MBS-dedicated DRX operation (i.e., per G-RNTI).

[0046] In particular, if a dedicated DRX operation for the MBS is configured for the G-RNTI, the UE can monitor the PDCCH for this G-RNTI by discontinuously using the specified DRX operation. The RRC controls its DRX operation by configuring the following timers. - MBS DRX-on Duration Timer (sometimes referred to as drx-onDurationTimerMBS), which indicates the duration at the start of the DRX cycle. - MBS DRX Inactivity Timer (sometimes denoted as drx-InactivityTimerMBS), which indicates the duration after a PDCCH occurs, where PDCCH indicates a new DL transmission for G-RNTI. - MBS DRX retransmission timer (sometimes represented as drx-RetransmissionTimerMBS): This indicates the maximum duration until a DL retransmission is received. - MBS DRX HARQ RTT Timer (sometimes represented as drx-HARQ-RTT-TimerDLMBS), which indicates the shortest previous duration for which a DL allocation for HARQ retransmission is expected by the MAC entity.

[0047] The activity period is the MBS DRX activity period, which refers to the period during which one of the following is active: drx-onDurationTimerMBS, drx-InactivityTimerMBS, or drx-RetransmissionTimerMBS. In particular, the MBS DRX inactivity period can be divided into the following two parts. - First activity period (activity time 1): The period during which one of drx-onDurationTimerMBS or drx-InactivityTimerMBS is running. During activity time 1, the UE monitors the group-common PDCCH for G-RNTI, and - Second activity period (activity time 2): The period during which drx-RetransmissionTimerMBS is running. During activity time 2, if only PTM retransmission via PTP is supported, the UE monitors the UE-dedicated PDCCH for the UE's C-RNTI, or if only PTM retransmission via PTM is supported, the UE monitors the group-common PDCCH for the G-RNTI, or if both PTM retransmission via PTP and PTM retransmission via PTM are supported, the UE monitors the PDCCH with scrambled CRC by the C-RNTI and the PDCCH with scrambled CRC by the G-RNTI.

[0048] The BS can transmit a PDCCH for G-RNTI while one of the MBS DRX on-duration timer and the MBS DRX inactivity timer is running, and at least one of the UE's PDCCH for C-RNTI and PDCCH for G-RNTI while the MBS DRX retransmission timer is running.

[0049] For example, the detailed procedure could include the following: When DRX is configured for G-RNTI or an MBS session, the MAC entity will be as follows: <1> If the DRX group has an activity time of 1, <2> Monitoring the group-wide PDCCH for G-RNTI <2> If the group-common PDCCH indicates DL transmission and HARQ is enabled / configured for G-RNTI, <3> After the completion of the corresponding transmission carrying DL HARQ feedback, start drx-HARQ-RTT-TimerMBS for the corresponding HARQ process with the first symbol. <3> Stop drx-RetransmissionTimerMBS for the corresponding HARQ process. <3> If HARQ-ACK feedback for group-wide HARQs is disabled, <4> After sending a PDSCH for the corresponding HARQ process, the drx-RetransmissionTimerMBS is started with the first symbol. <2> If the group-wide PDCCH indicates a new transmission about G-RNTI, <3> After PDCCH reception is complete, the drx-InactivityTimerMBS for this DRX is started or restarted with the first symbol. <1> If the DRX group has an activity time of 2, <2> If only PTM retransmission via PTP is supported, the UE monitors a UE-dedicated PDCCH for the UE's C-RNTI; or, if only PTM retransmission via PTM is supported, the UE monitors a group-common PDCCH for the G-RNTI; or, if both PTM retransmission via PTP and PTM retransmission via PTM are supported, the UE monitors a PDCCH with scrambled CRC by the C-RNTI and a PDCCH with scrambled CRC by the G-RNTI.

[0050] In this embodiment, the UE will distinguish when a retransmission is coming from the PTM or PTP so that the UE can decide to monitor the C-RNTI or G-RNTI during activity time 2.

[0051] For example, the BS may indicate in DCI whether the corresponding retransmission is scrambled using G-RNTI (PTM retransmission via PTM) or scrambled using C-RNTI (PTM retransmission via PTP). After receiving the instruction, the UE can know whether to monitor G-RNTI or C-RNTI.

[0052] In another example, the UE can decide whether to monitor G-RNTI or C-RNTI depending on whether MBS DRX-related retransmission timers (such as drx-RetransmissionTimerMBS, drx-HARQ-RTT-TimerDLMBS) are configured. If drx-RetransmissionTimerMBS or drx-HARQ-RTT-TimerDLMBS are configured, the UE can monitor G-RNTI for retransmission; otherwise, the UE can monitor C-RNTI for retransmission.

[0053] When switching between PTM and PTP, PTM transmissions (including initial PTM transmissions and PTM retransmissions) can be disabled or deactivated. If PTM transmissions are disabled or deactivated, the UE can disable or suspend MBS-only DRX operation. For example, if the UE receives a PTM disable or deactivate command from the network, the UE can stop all related timers (e.g., drx-onDurationTimerMBS) and cannot monitor the group common PDCCH with a CRC scrambled by G-RNTI.

[0054] Figure 5 illustrates a method for configuring DRX operation for MBS according to another embodiment of this application.

[0055] As shown in Figure 5, (1) can represent a PTM transmission including an initial PTM transmission and / or a PTM retransmission via PTM, (2) can represent a PTM retransmission via PTP, (3) can represent a PTP transmission, and (4) can represent a unicast transmission.

[0056] In this embodiment, the MBS-dedicated DRX operation is configured only for PTM transmission (1), while the unicast DRX operation is used for PTM retransmission via PTP (2), PTP transmission (3), and unicast transmission (4).

[0057] In this embodiment, the MBS-dedicated DRX operation may be per G-RNTI or per MBS session. In particular, when the MBS-dedicated DRX operation is configured for a G-RNTI, the UE can monitor the PDCCH for that G-RNTI by discontinuously using the specified DRX operation. The RRC controls its DRX operation by configuring the following timers. - MBS DRX-on Duration Timer (sometimes referred to as drx-onDurationTimerMBS), which indicates the duration at the start of a DRX cycle. - MBS DRX Inactivity Timer (sometimes denoted as drx-InactivityTimerMBS), which indicates the duration after a PDCCH occurs, where PDCCH indicates a new DL transmission for G-RNTI. - MBS DRX retransmission timer (sometimes represented as drx-RetransmissionTimerMBS): This indicates the maximum duration until a DL retransmission is received. - MBS DRX HARQ RTT Timer (sometimes represented as drx-HARQ-RTT-TimerDLMBS), which indicates the shortest previous duration for which a DL allocation for HARQ retransmission is expected by the MAC entity.

[0058] In this embodiment, drx-RetransmissionTimerMBS and drx-HARQ-RTT-TimerDLMBS cannot be configured, and the conventional drx-HARQ-RTT-TimerDL and drx-RetransmissionTimerDL can be reused as a retransmission timer (drx-RetransmissionTimerMBS) and HARQ RTT timer (drx-HARQ-RTT-TimerDLMBS) for MBS DRX operation.

[0059] The activity period may include the activity period for MBS DRX operation and the activity period for unicast DRX operation.

[0060] The active time period for MBS DRX operation refers to the period during which one of the MBS DRX on-duration timers or the MBS DRX inactivity timer is running. During the active time period for MBS DRX operation, the UE monitors the group common PDCCH for G-RNTI.

[0061] The activity period for unicast DRX operation refers to the period during which the MBS DRX retransmission timer is running. During the activity period for unicast DRX operation, the UE initiates unicast DRX operation and monitors the PDCCH for the UE's C-RNTI.

[0062] For example, the detailed procedure could include the following: When DRX is configured for G-RNTI or an MBS session, the MAC entity will be as follows: <1> If the DRX group is active, <2> Monitoring the group-wide PDCCH for G-RNTI <2> If the group-common PDCCH indicates DL transmission and HARQ is enabled / configured for G-RNTI, <3> Start drx-HARQ-RTT-TimerMBS for the corresponding HARQ process. <3> Stop drx-RetransmissionTimerMBS for the corresponding HARQ process. <3> If the PDSCH-to-HARQ_feedback timing indicates a non-numeric k1 value, <4> After sending a PDSCH for the corresponding HARQ process, the drx-RetransmissionTimerMBS is started with the first symbol. <4> The unicast DRX operation is initiated considering the drx-RetransmissionTimerMBS as the activity time for the unicast DRX operation.

[0063] Figure 6 illustrates a method for configuring DRX operation for MBS according to another embodiment of the present application.

[0064] As shown in Figure 6, (1) can represent a PTM transmission including an initial PTM transmission and / or a PTM retransmission via PTM, (2) can represent a PTM retransmission via PTP, (3) can represent a PTP transmission, and (4) can represent a unicast transmission.

[0065] In this embodiment, the MBS-dedicated DRX operation is configured for PTM transmission (1), PTM retransmission via PTP (2), and PTP transmission (3), while the unicast DRX operation is used for unicast transmission (4).

[0066] In this embodiment, the MBS-dedicated DRX operation may be per G-RNTI. Also, the HARQ retransmission-related timers (for example, the MBS DRX retransmission timer and the MBS DRX HARQ RTT timer) are also MBS-dedicated. For example, the HARQ retransmission-related timer may be per MBS-dedicated DRX operation (i.e., per G-RNTI).

[0067] In particular, if a dedicated DRX operation for the MBS is configured for the G-RNTI, the UE can monitor the group-common PDCCH for this G-RNTI by discontinuously using the specified DRX operation. The RRC controls its DRX operation by configuring timers such as drx-onDurationTimerMBS, drx-InactivityTimerMBS, drx-RetransmissionTimerMBS, and drx-HARQ-RTT-TimerDLMBS. The meaning of the timers here is the same as described above and will not be described in detail.

[0068] The activity period refers to the period during which one of the following is running: drx-onDurationTimerMBS, drx-InactivityTimerMBS, or drx-RetransmissionTimerMBS. During the activity period, the UE monitors the group-common PDCCH for G-RNTI and the UE-specific PDCCH for the UE's C-RNTI.

[0069] The BS can transmit PDCCH for G-RNTI and PDCCH for UE's C-RNTI while one of the following timers is active: the MBS DRX on-duration timer, the MBS DRX inactivity timer, and the MBS DRX retransmission timer.

[0070] For example, the detailed procedure could include the following: When DRX is configured for G-RNTI or an MBS session, the MAC entity will be as follows: <1> If the DRX group is active, <2> Monitor both the group-wide PDCCH for G-RNTI and the UE-specific PDCCH for C-RNTI. <2> If PDCCH indicates DL transmission and HARQ is enabled / configured for G-RNTI, <3> Start drx-HARQ-RTT-TimerMBS for the corresponding HARQ process. <3> Stop drx-RetransmissionTimerMBS for the corresponding HARQ process. <3> If the PDSCH-to-HARQ_feedback timing indicates a non-numeric k1 value, <4> After sending a PDSCH for the corresponding HARQ process, the drx-RetransmissionTimerMBS is started with the first symbol. <2> If PDCCH indicates a new transmission about G-RNTI, <3> After PDCCH reception is complete, the drx-InactivityTimerMBS for this DRX is started or restarted with the first symbol.

[0071] Currently, both PTP and unicast transmissions are scrambled by the same C-RNTI, and as a result, the UE cannot distinguish between PTP and unicast transmissions at the physical layer.

[0072] In this embodiment, since different DRX operations are used for PTP transmission and unicast transmission, the UE will distinguish between PTP transmission and unicast transmission.

[0073] For example, a BS can assign a C-RNTI for PTP transmission that is different from a C-RNTI for unicast transmission. If the PDCCH is scrambled by a C-RNTI for PTP transmission for each MBS session, the UE operates the MBS-only DRX operation. If the PDCCH is scrambled by a C-RNTI for unicast transmission, the UE operates the unicast DRX operation.

[0074] In another example, the BS can assign a dedicated HARQ process ID for an MBS session. The UE can use the HARQ process ID to identify a PTP transmission. If the HARQ process ID is for MBS, the UE will activate MBS-only DRX operation.

[0075] In yet another example, the BS can indicate during DCI whether the transmission is a PTP transmission or a unicast transmission. After receiving the instruction, the UE will know whether to perform an MBS-only DRX operation or a unicast operation.

[0076] In the above embodiment, the MBS DRX operation and the unicast DRX operation are different. In another embodiment, a common DRX operation can be configured for MBS and unicast transmissions, and separate retransmission-related timers can be configured for MBS and unicast transmissions.

[0077] In this embodiment, a common DRX operation is used for the MBS and unicast bearer. However, a separate retransmission-related timer is configured for the MBS. For example, drx-HARQ-RTT-TimerMBS and drx-HARQ-RTT-TimerMBS are configured for the MBS for PTM retransmission. Both drx-RetransmissionTimerMBS and drx-RetransmissionTimerDL are active times for the DRX operation.

[0078] For example, the detailed procedure could include the following: When DRX is configured for G-RNTI or an MBS session, the MAC entity will be as follows: <1> If the DRX group is active, <2> Monitoring PDCCHs (including both group-common PDCCHs for G-RNTIs and UE-specific PDCCHs for C-RNTIs) <2> If the group-common PDCCH indicates DL transmission and HARQ is enabled / configured for G-RNTI, <3> Start drx-HARQ-RTT-TimerMBS for the corresponding HARQ process. <3> Stop drx-RetransmissionTimerMBS for the corresponding HARQ process. <3> If the PDSCH-to-HARQ_feedback timing indicates a non-numeric k1 value, <4> After sending a PDSCH for the corresponding HARQ process, the drx-RetransmissionTimerMBS is started with the first symbol. <2> If the UE-dedicated PDCCH indicates DL transmission, <3> Start drx-HARQ-RTT-TimerDL for the corresponding HARQ process. <3> Stop drx-RetransmissionTimerDL for the corresponding HARQ process. <3> If the PDSCH-to-HARQ_feedback timing indicates a non-numeric k1 value, <4> After sending a PDSCH for the corresponding HARQ process, the drx-RetransmissionTimerDL is started with the first symbol.

[0079] In yet another embodiment, separate activity times and common configurations for other timers are configured for MBS and unicast transmission.

[0080] In this embodiment, an MBS-dedicated on-duration timer and / or an MBS-dedicated inactivity timer is configured for each MBS session (G-RNTI). Other timers, such as MBS-dedicated DRX operation and unicast DRX operation, can share the following parameter values: DRX slot offset (drx-SlotOffset), DRX retransmission timer (drx-RetransmissionTimerDL), a DRX long cycle start offset (drx-LongCycleStartOffset), DRX short cycle (drx-ShortCycle) (optional), DRX short cycle timer (drx-ShortCycleTimer) (optional), and DRX HARQ RTT timer (drx-HARQ-RTT-TimerDL).

[0081] In another embodiment, the DRX start offset and DRX slot offset may also be MBS-specific or per MBS session.

[0082] Embodiments of this application can achieve effective power savings for NR MBS for UEs in highly reliable multicast services that support HARQ and retransmission.

[0083] Figure 7 illustrates an apparatus according to some embodiments of this application. In some embodiments of this application, apparatus 700 may be UE102 (UE102a or UE102b) as shown in Figure 1 or a UE in other embodiments of this application.

[0084] As shown in Figure 7, the apparatus 700 may include a receiver 701, a transmitter 703, a processor 705, and a non-temporary computer-readable medium 707. The non-temporary computer-readable medium 707 has computer-executable instructions stored therein. The processor 705 is configured to be coupled with the non-temporary computer-readable medium 707, the receiver 701, and the transmitter 703. In some other embodiments of this application, in accordance with practical requirements, the apparatus 700 may be intended to include further computer-readable mediums, receivers, transmitters, and processors. In some embodiments of this application, the receiver 701 and the transmitter 703 may be integrated into a single device such as a wireless transceiver. In some embodiments, the apparatus 700 may further include an input device, memory, and / or other components.

[0085] In some embodiments of this application, a non-temporary computer-readable medium 707 can store computer-executable instructions thereon, causing a processor 705 to perform methods implemented by the UE in accordance with embodiments of this application. For example, the processor 705 may be configured to perform, during an activity time period, monitoring for initial PTM transmissions having a first identifier, and monitoring for retransmissions having either a first identifier, a second identifier, or both the first and second identifiers. It should be understood that the processor 705 may be further configured to perform other operations or actions described above, which are not described in detail to avoid repetition.

[0086] Figure 8 illustrates another apparatus according to some embodiments of the present application. In some embodiments of the present application, apparatus 800 may be BS101 as shown in Figure 1, or BS in other embodiments of the present application.

[0087] As shown in Figure 8, the apparatus 800 may include a receiver 801, a transmitter 803, a processor 805, and a non-temporary computer-readable medium 807. The non-temporary computer-readable medium 807 has computer-executable instructions stored therein. The processor 805 is configured to be coupled with the non-temporary computer-readable medium 807, the receiver 801, and the transmitter 803. In some other embodiments of this application, in accordance with practical requirements, the apparatus 800 is intended to include further computer-readable mediums, receivers, transmitters, and processors. In some embodiments of this application, the receiver 801 and the transmitter 803 can be integrated into a single device such as a wireless transceiver. In some embodiments, the apparatus 800 may further include an input device, memory, and / or other components.

[0088] In some embodiments of this application, a non-temporary computer-readable medium 807 stores computer-executable instructions thereon, causing the device 800 to execute a method implemented by BS according to embodiments of this application.

[0089] Some embodiments of this disclosure can be disclosed below.

[0090] Embodiment 1 A method performed by user equipment (UE) comprising intermittent receive (DRX) operation of multicast and broadcast services (MBS), wherein during the activity period for MBS DRX operation, A step of monitoring a point-to-multipoint (PTM) initial transmission associated with an MBS from a base station, wherein the PTM initial transmission is further associated with a first identifier, A step of monitoring PTM retransmissions associated with an MBS from a base station, wherein the PTM retransmission is further associated with a first identifier, or a second identifier, or both the first identifier and the second identifier. Methods that include...

[0091] Embodiment 2 The method of Embodiment 1, wherein the first identifier is a group radio network temporary identifier (G-RNTI) and the second identifier is a UE cell radio network temporary identifier (C-RNTI).

[0092] Embodiment 3 MBS DRX operation is configured for PTM initial transmission and PTM retransmission. The method of Embodiment 1, wherein the activity period is the MBS DRX activity period, and the MBS DRX activity period includes a first MBS DRX activity period and a second MBS DRX activity period, the first MBS DRX activity period indicates an activity period in which one of the MBS DRX on-duration timer and the MBS DRX inactivity timer is running, and the second MBS DRX activity period indicates an activity period in which the MBS DRX retransmission timer is running.

[0093] Embodiment 4 During the first MBS DRX activity period, the UE monitors the Physical Downlink Control Channel (PDCCH) for the first identifier. The method of Embodiment 3, wherein during the second MBS DRX activity period, the UE monitors the PDCCH for the second identifier in the case of PTM retransmission via PTP, the UE monitors the PDCCH for the first identifier in the case of PTM retransmission via PTM, or the UE monitors the PDCCH for the second identifier and the PDCCH for the first identifier when both PTM retransmission via PTP and PTM retransmission via PTM are supported.

[0094] Embodiment 5 In other words, An indication in the Downlink Control Information (DCI) that PTM retransmission is via PTP or via PTM, or When the MBS DRX related retransmission timer is configured The method of Embodiment 4, wherein the UE determines whether to monitor the PDCCH for a second identifier or for a first identifier based on at least one of the following.

[0095] Embodiment 6 The method of Embodiment 3, in the case of switching between PTM and PTP, the PTM transmission is disabled or deactivated, and the UE disables or pauses the MBS DRX operation.

[0096] Embodiment 7 MBS DRX operation is configured for PTM initial transmission, and unicast DRX operation is configured for PTM retransmission via PTP. The method of Embodiment 1, wherein the activity period includes an activity period for MBS DRX operation and an activity period for unicast DRX operation, the activity period for MBS DRX operation represents the activity period during which one of the MBS DRX on-duration timer and the MBS DRX inactivity timer is running, and the activity period for unicast DRX operation represents the activity period during which the MBS DRX retransmission timer is running.

[0097] Embodiment 8 During the activity period for MBS DRX operation, the UE monitors the PDCCH for the first identifier, The method of Embodiment 7, wherein during the activity time period for unicast DRX operation, the UE initiates unicast DRX operation and monitors the PDCCH for a second identifier.

[0098] Embodiment 9 The method of Embodiment 7, in which the Hybrid Automatic Retransmission Request (HARQ) Round-Trip Time (RTT) timer and the retransmission timer for unicast DRX operation are reused as the retransmission timer and the HARQ RTT timer for MBS DRX operation.

[0099] Embodiment 10 The MBS DRX operation is configured for PTM initial transmission, PTM retransmission, and PTP transmission. The method of Embodiment 1, wherein the activity period is the activity period during which one of the MBS DRX on-duration timer, the MBS DRX inactivity timer, and the MBS DRX retransmission timer is running.

[0100] Embodiment 11 The method of Embodiment 10, wherein during the activity period, the UE monitors the PDCCH for a first identifier and the PDCCH for a second identifier.

[0101] Embodiment 12 Unicast DRX operation is configured for unicast transmission, and the UE does the following, namely: PDCCH is scrambled by a first C-RNTI for PTP transmissions, or by a second C-RNTI for unicast transmissions that is different from the first C-RNTI for PTP transmissions. A HARQ process ID dedicated to the MBS session indicating PTP transmission, and DCI indications whether the transmission is a PTP transmission or a unicast transmission. A method according to embodiment 11, which distinguishes between PTP transmission and unicast transmission based on at least one of the following.

[0102] Embodiment 13 The method of Embodiment 1, in which MBS DRX operation and unicast DRX operation are the same DRX operation.

[0103] Embodiment 14 The method of Embodiment 13, wherein the MBS DRX HARQ RTT timer and the MBS DRX retransmission timer are configured for PTM retransmission.

[0104] Embodiment 15 The method of Embodiment 13, wherein during the activity period, the UE monitors the PDCCH for a first identifier and the PDCCH for a second identifier.

[0105] Embodiment 16 The method of Embodiment 1, wherein an MBS on-duration timer and / or an MBS DRX inactivity timer are configured for the MBS.

[0106] Embodiment 17 The method of Embodiment 16, wherein the MBS DRX operation and the unicast DRX operation share at least one of the following parameter values: DRX slot offset, DRX retransmission timer, DRX long cycle start offset, DRX short cycle, DRX short cycle timer, and DRX HARQ RTT timer.

[0107] Embodiment 18 The method of Embodiment 16, wherein the DRX start offset and DRX slot offset are dedicated to the MBS.

[0108] Embodiment 19 Steps to configure values ​​for at least one timer for point-to-multipoint (PTM) initial transmission, PTM retransmission, and point-to-point (PTP) transmission of multicast and broadcast service (MBS) intermittent receive (DRX) operations to a UE. A method implemented by a base station (BS), including the following.

[0109] Embodiment 20 The method of Embodiment 19, wherein at least one timer includes one or more of the following: an MBS DRX on-duration timer, an MBS DRX inactivity timer, an MBS DRX retransmission timer, and an MBS DRX HARQ RTT timer.

[0110] Embodiment 21 The steps include sending a PTM initial transmission having a first identifier, The steps include: transmitting a PTM retransmission having a first identifier or a second identifier; The method of embodiment 20 further includes the method of embodiment 20.

[0111] Embodiment 22 The method of Embodiment 21, wherein the first identifier is a group radio network temporary identifier (G-RNTI) and the second identifier is a UE cell radio network temporary identifier (C-RNTI).

[0112] Embodiment 23 BS, While one of the MBS DRX on-duration timers and the MBS DRX inactive timer is running, PDCCH for the first identifier, and While the MBS DRX retransmission timer is running, at least one of the PDCCH for the second identifier and the PDCCH for the first identifier The method of transmission according to Embodiment 21.

[0113] Embodiment 24 The method of Embodiment 21, in which the DRX HARQ RTT timer and the DRX retransmission timer for unicast DRX operation are reused as a retransmission timer and a HRX RTT timer for MBS DRX operation.

[0114] Embodiment 25 The method of Embodiment 21, wherein the BS transmits a PDCCH for a first identifier and a PDCCH for a second identifier while one of the MBS DRX on duration timer, MBS DRX inactivity timer, and MBS DRX retransmission timer is running.

[0115] Embodiment 26 The method of Embodiment 20, in which the MBS DRX HARQ RTT timer and the MBS DRX retransmission timer are configured for PTM retransmission when the MBS DRX operation and unicast DRX operation are common DRX operations for the UE.

[0116] Embodiment 27 The method of Embodiment 20, wherein an MBS DRX on-duration timer and an MBS DRX inactivity timer are configured for the MBS, and for unicast DRX operation, at least one of the DRX slot offset, DRX retransmission timer, DRX long cycle start offset, DRX short cycle, DRX short cycle timer, and DRX HARQ RTT timer is shared with the MBS DRX operation.

[0117] Embodiment 28 Processor and Wireless transceiver coupled to the processor and Equipped with, The processor, A wireless transceiver configured to carry out a method according to any one of Embodiments 1 to 27.

[0118] Those skilled in the art should understand that as the technology develops and progresses, the terminology used in this application may change, and that this should not affect or limit the principles and spirit of this application.

[0119] Those skilled in the art will understand that the steps of the methods described in relation to the embodiments disclosed herein can be embodied in hardware directly, in software modules executed by a processor, or in combination of both. The software modules can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art. In addition, in some embodiments, the steps of the methods can reside as one or any combination or set of code and / or instructions on a non-temporary computer-readable medium that can be incorporated into a computer program product.

[0120] While this disclosure is described in its specific embodiments, it will be apparent to those skilled in the art that many alternative, modified, and altered forms will become apparent. For example, various components of these embodiments can be interchanged, added, or substituted in other embodiments. Furthermore, not all elements in each figure are necessary for the operation of the disclosed embodiments. For example, those skilled in the art of the disclosed embodiments can make and use the teachings of this disclosure by simply adopting the elements of the independent claims. Thus, the embodiments of this disclosure as described herein are intended to be illustrative and not limiting. Various modifications can be made without departing from the spirit and scope of this disclosure.

[0121] In this text, the terms “comprise,” “comprising,” or any other variations thereof are intended to cover non-exclusive inclusion, and as a result, a process, method, article, or apparatus containing a list of elements may contain not only those elements but also other elements not expressly listed or that are specific to such process, method, article, or apparatus. Elements preceded by “a,” “an,” etc., do not, without further restriction, exclude the presence of additional identical elements in the process, method, article, or apparatus containing the element. The term “another” is defined as at least two or more. As used herein, terms such as “including,” “having,” etc., are defined as “comprising.” [Explanation of Symbols]

[0122] 100 Wireless Communication Systems 101 BS 102 UE 102a UE 102b UE 201 Operation 202 Operation 700 equipment 701 Receiver 703 Transmitter 705 Processor 707 Non-temporary computer-readable media 800 equipment 801 Receiver 803 Transmitter 805 Processor 807 Non-temporary computer-readable media

Claims

1. A method performed by user equipment (UE) comprising intermittent receive (DRX) operation of multicast and broadcast services (MBS), wherein during the activity period for MBS DRX operation, A step of monitoring a point-to-multipoint (PTM) initial transmission associated with an MBS from a base station, wherein the PTM initial transmission is further associated with a first identifier. A step of monitoring PTM retransmissions associated with the MBS from a base station, wherein the PTM retransmission is further associated with the first identifier, or the second identifier, or both the first identifier and the second identifier. Includes, A method wherein the MBS DRX operation is configured for the initial PTM transmission, and the unicast DRX operation is configured for the PTM retransmission via PTP, and the unicast DRX operation shares a DRX retransmission timer and a DRX HARQ RTT timer with the MBS DRX operation to determine the identifier to monitor for the PTM retransmission.

2. The method according to claim 1, wherein the first identifier is a group radio network temporary identifier (G-RNTI), and the second identifier is a cell radio network temporary identifier (C-RNTI) of the UE.

3. The MBS DRX operation is configured for the initial PTM transmission and the PTM retransmission, The method according to claim 1, wherein the activity period is an MBS DRX activity period, and the MBS DRX activity period includes a first MBS DRX activity period and a second MBS DRX activity period, the first MBS DRX activity period represents an activity period in which one of the MBS DRX on-duration timer and the MBS DRX inactivity timer is running, and the second MBS DRX activity period represents an activity period in which the MBS DRX retransmission timer is running.

4. During the first MBS DRX activity period, the UE monitors the physical downlink control channel (PDCCH) for the first identifier. The method according to claim 3, wherein during the second MBS DRX activity period, the UE monitors the PDCCH for the second identifier in the case of PTM retransmission via PTP, the UE monitors the PDCCH for the first identifier in the case of PTM retransmission via PTM, or the UE monitors the PDCCH for the second identifier and the PDCCH for the first identifier when both PTM retransmission via PTP and PTM retransmission via PTM are supported.

5. An indication in the Downlink Control Information (DCI) that the PTM retransmission is via PTP or via PTM, or When the MBS DRX related retransmission timer is configured The method according to claim 4, wherein the UE determines whether to monitor the PDCCH for the second identifier or the PDCCH for the first identifier based on at least one of the following.

6. The method according to claim 1, wherein the activity period includes an activity period for the MBS DRX operation and an activity period for the unicast DRX operation, the activity period for the MBS DRX operation represents an activity period in which one of the MBS DRX on-duration timer and the MBS DRX inactivity timer is running, and the activity period for the unicast DRX operation represents an activity period in which the MBS DRX retransmission timer is running.

7. During the activity period for the MBS DRX operation, the UE monitors the PDCCH for the first identifier, The method according to claim 6, wherein during the activity time period for the unicast DRX operation, the UE initiates the unicast DRX operation and monitors the PDCCH for the second identifier.

8. The MBS DRX operation is configured for the initial PTM transmission, the PTM retransmission, and the PTP transmission. The method according to claim 1, wherein the activity period refers to the activity period during which one of the MBS DRX on duration timer, MBS DRX inactivity timer, and MBS DRX retransmission timer is operating.

9. The method according to claim 8, wherein during the activity period, the UE monitors the PDCCH for the first identifier and the PDCCH for the second identifier.

10. The method according to claim 1, wherein the MBS DRX operation and the unicast DRX operation are the same DRX operation.

11. The method according to claim 10, wherein the MBS DRX HARQ RTT timer and the MBS DRX retransmission timer are configured for the PTM retransmission.

12. The method according to claim 10, wherein during the activity period, the UE monitors the PDCCH for the first identifier and the PDCCH for the second identifier.

13. The method according to claim 1, wherein an MBS DRX on-duration timer and / or an MBS DRX inactivity timer are configured for the MBS.

14. The method according to claim 13, wherein the MBS DRX operation and the unicast DRX operation further share at least one of the following parameter values: DRX slot offset, DRX long cycle start offset, DRX short cycle, and DRX short cycle timer.

15. Processor and A wireless transceiver coupled to the aforementioned processor Equipped with, The aforementioned processor, The wireless transceiver is configured to implement the method described in any one of claims 1 to 14. A device configured in such a way.

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