Data transmission method and device for multicast broadcast service

Abstract

A method for providing a multicast broadcast service is disclosed. One embodiment of the present application provides a method performed by a UE, comprising: receiving data packets in a first mode in a first cell; sending a data reception status report during or after a handover and / or during or after a data transmission mode switch; receiving lost data packets during the data transmission mode switch and / or during the handover; and receiving data packets in a second cell in a second mode. Related devices are also disclosed.

Description

Technical Field

[0001] Various example embodiments are directed to data transmission methods and apparatus for Multicast Broadcast Service (MBS). Background Art

[0002] In 3GPP (Third Generation Partnership Project), several data transmission modes of MBS, such as point-to-point (PTP) mode and point-to-multipoint (PTM) mode, are mixed in some areas, and identified use cases that can benefit from this feature include, but are not limited to, public safety and mission-critical applications, vehicle-to-everything (V2X) applications, transparent Internet Protocol version 4 (IPv4) / IPv6 multicast delivery, Internet Protocol television (IPTV), wireless software delivery, group communication, and Internet of Things (IoT) applications. Summary of the Invention

[0003] One embodiment of the present application provides a method for data transmission performed by a user equipment (UE), comprising: receiving data packets in a first cell in a first mode; sending a data reception status report during or after switching and / or during or after data transmission mode switching; receiving lost data packets during data transmission mode switching and / or during switching; and receiving data packets in a second cell in a second mode.

[0004] Another embodiment of the present application provides a method for data transmission performed by a base station (BS), comprising: transmitting data packets in a first mode in a first cell; receiving a data reception status report during or after switching and / or during or after data transmission mode switching; transmitting lost data packets during data transmission mode switching and / or during switching according to the data reception status report; and transmitting data packets in a second cell in a second mode.

[0005] Another embodiment of the present application provides a method for data transmission performed by a source BS, comprising: transmitting data packets in a first mode in a first cell; sending a multicast and broadcast service (MBS) reception status to a target BS during switching, wherein the MBS reception status includes at least a service identifier (ID) and a first mode associated with the data transmission; and forwarding lost data packets during switching and / or during switching of the data transmission mode to the target BS; and stopping transmitting data packets in the first mode in the first cell.

[0006] Another embodiment of the present application provides a method for data transmission performed by a target BS, comprising: receiving an MBS reception status from a source BS during a handover, wherein the MBS reception status includes at least a service ID and a first mode associated with data transmission; receiving a data reception status report during or after the handover and / or during or after a data transmission mode switch; receiving lost data packets from the source BS during the handover and / or during a data transmission mode switch and forwarding the lost data packets according to the data reception status report; and transmitting data packets in a second mode.

[0007] Yet another embodiment of the present application provides an apparatus that indicates a non-transitory computer-readable medium having computer-executable instructions stored thereon, a receiving circuit system, a transmitting circuit system, and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement a method performed by a UE. The method includes: receiving data packets in a first mode in a first cell; sending a data reception status report during or after a handover and / or during or after a data transmission mode switch; receiving lost data packets during a data transmission mode switch and / or during a handover; and receiving data packets in a second mode in a second cell.

[0008] Yet another embodiment of the present application provides an apparatus that indicates a non-transitory computer-readable medium having computer-executable instructions stored thereon, a receiving circuit system, a transmitting circuit system, and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement a method performed by a base station. The method includes: transmitting data packets in a first mode in a first cell; receiving a data reception status report during or after a handover and / or during or after a data transmission mode switch; transmitting lost data packets during a data transmission mode switch and / or during a handover according to the data reception status report; and transmitting data packets in a second mode in a second cell.

[0009] Another embodiment of the present application provides an apparatus that indicates a non-transitory computer-readable medium having computer-executable instructions stored thereon, a receiving circuit system, a transmitting circuit system, and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement a method performed by a source base station. The method includes: transmitting data packets in a first mode in a first cell; sending a multicast and broadcast service (MBS) reception status to a target base station during handover, wherein the MBS reception status includes at least a service identifier (ID) and a first mode associated with the data transmission; and forwarding lost data packets during handover and / or during the switching of the data transmission mode to the target base station; and ceasing to transmit data packets in the first mode in the first cell.

[0010] Another embodiment of the present application provides an apparatus that indicates a non-transitory computer-readable medium having computer-executable instructions stored thereon, a receiving circuit system, a transmitting circuit system, and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement a method performed by a target base station. The method includes: receiving an MBS reception status from a source base station during a handover, wherein the MBS reception status includes at least a service ID and a first mode associated with data transmission; receiving a data reception status report during or after the handover and / or during or after a data transmission mode switch; receiving lost data packets from the source base station during the handover and / or during a data transmission mode switch and forwarding the lost data packets according to the data reception status report; and transmitting data packets in a second mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Some example embodiments will now be described, by way of non-limiting examples, with reference to the accompanying drawings.

[0012] Figure 1 An exemplary RAN-based approach for MBS is described.

[0013] Figure 2 Describes a dedicated bearer associated with a multicast bearer.

[0014] Figure 3 An exemplary signal sequence for switching from PTM mode to PTP mode without handover is illustrated.

[0015] Figure 4 An example of a signal sequence for switching from PTP mode to PTM mode without handover is described.

[0016] Figure 5An example of a signal sequence for handover under the same BS without data transmission mode switching is described.

[0017] Figure 6 An example of a signal sequence for handover between different BSs without data transmission mode switching is described.

[0018] Figure 7 An example of a signal sequence for handover within the same BS with data transmission mode switching is described.

[0019] Figure 8 An example of a signal sequence for handover between different BSs with data transmission mode switching is described.

[0020] Figure 9 An exemplary block diagram illustrating a UE according to an embodiment of the present disclosure.

[0021] Figure 10 An exemplary RAN-based method performed by a BS is described.

[0022] Figure 11 An exemplary RAN-based method performed by a source BS is described.

[0023] Figure 12 An exemplary RAN-based method performed by a target BS is described.

[0024] Figure 13 An exemplary block diagram illustrating a BS according to an embodiment of the present disclosure.

[0025] Figure 14 Describes exemplary final packaging instructions.

[0026] Figure 15 Describes an exemplary end tag. DETAILED DESCRIPTION

[0027] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present invention, and is not intended to represent the only form in which the present invention can be practiced. It should be understood that the same or equivalent functions can be achieved by different embodiments that are intended to be included in the spirit and scope of the present invention.

[0028] Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings. To facilitate understanding, the embodiments are provided in the context of specific network architectures and new service scenarios (e.g., 3GPP 5G, etc.). It should be noted that as network architectures and new service scenarios evolve, all embodiments in this application are also applicable to similar technical problems, and further, the terms used in this application may change without affecting the principles of this application.

[0029] The present disclosure generally relates to MBS data transmission. For example, a UE can receive data from a base station in either PTP mode or PTM mode. Furthermore, due to, for example, changes in radio link quality, stricter Quality of Service (QoS) requirements, or other changing conditions, the network may decide to move the UE to PTP mode or PTM mode for MBS data transmission. For example, if the radio link quality decreases, the UE may use PTP mode to receive data from the base station; and if the radio link quality improves, the UE may use PTM mode to receive data from the base station.

[0030] Switching data transmission modes can be achieved through application-layer solutions. However, if the data transmission mode is switched and / or a handover occurs, data transmission continuity and losslessness may not be guaranteed. For example, in Long Term Evolution (LTE), Single-Cell Persistent Transport Mode (SC-PTM) uses an application-layer solution to support data transmission mode switching between PTP and PTM modes. This switching delay can exceed 200ms. If the data transmission mode switch is accompanied by a handover, the switching delay can be even greater. Furthermore, some data packets may be lost during the data transmission mode switch and / or handover.

[0031] Switching of data transmission modes can be implemented entirely at the Radio Access Network (RAN) layer. A RAN-based solution significantly reduces switching latency, allowing UEs to switch between PTP and PTM modes more efficiently. Regardless of whether the RAN uses PTM, PTP, or both in a particular cell, the same tunnel for MBS flows can be used. The RAN-based solution targets applications / UEs that indicate their interest (e.g., joining / leaving) in receiving MBS services.

[0032] Figure 1 An exemplary RAN-based method 100 for MBS performed by a UE to receive data packets from a BS is described. Figure 1 As shown in FIG1 , method 100 may include step 110 of receiving data packets in a first mode in a first cell, step 120 of sending a data reception status report to a BS during or after switching from the first cell to the second cell and / or during or after switching the data transmission mode from the first mode to the second mode, step 130 of receiving lost data packets during or after the data transmission mode switching and / or during or after the cell switching according to the data reception status report, and step 140 of receiving data packets in the second mode in the second cell. The data reception status report is used for lossless data transmission.

[0033] In some embodiments, each of the first mode and the second mode may be one of a PTP mode and a PTM mode, and may be associated with a first bearer and a second bearer, respectively.

[0034] In some embodiments, each of the first bearer and the second bearer may support both the first mode and the second mode.

[0035] In some embodiments, each of the first bearer and the second bearer is one of a multicast bearer for data transmission in PTM mode and a unicast bearer for data transmission in PTP mode. In some embodiments, the multicast bearer is scrambled by a group radio network temporary identifier (G-RNTI) in at least one cell, and the unicast bearer is scrambled by a cell radio network temporary identifier (C-RNTI).

[0036] Since multicast bearers are cell- or multicast area-specific, it is inappropriate to use multicast bearers to transmit or receive UE-specific information. Therefore, in some embodiments, a dedicated bearer associated with the multicast bearer is established for transmitting or receiving UE-specific information (e.g., a data reception status report, or a last packet indication or end marker for stopping data transmission mode or missing data packets). In some embodiments, the dedicated bearer can be the same as the unicast bearer.

[0037] Figure 2 Describes a dedicated bearer associated with a multicast bearer. Figure 2 As shown in FIG, the BS transmits data packets to UE 1 and UE 2 via the multicast bearer in PTM mode. Two dedicated bearers are established in association with the multicast bearer to send or receive UE-specific information of UE 1 and UE 2, respectively.

[0038] In some embodiments, to support service continuity or data transmission continuity and lossless data transmission, a common sequence number function is used for data packet transmission. Data reception status reports are associated with a common sequence number (SN), where the common SN is shared by PTM and PTP modes, and / or shared by different cells, and / or shared by different base stations. Based on the data reception status reports associated with the common SN, the base station clearly knows which data packets were correctly received by the UE and which data packets were lost. In some embodiments, the common sequence number is a Packet Data Convergence Protocol (PDCP) SN or a PDCP count value.

[0039] In some embodiments, the data reception status report includes at least one of the following items: a maximum common SN or count value for data packets received in the first mode, a bitmap indicating which data packets are lost and which packets are correctly received, a common SN or count value of the first lost packet when receiving data packets in the first mode, and a combined data reception status for the first mode and the second mode and / or in the first cell and in the second cell. If the second mode is the PTM mode, the data reception status report further includes at least a minimum common SN or count value for data packets received among all UEs in the second mode.

[0040] In some embodiments, the data reception status report is sent by the UE based on at least one of: stopping receiving data packets in the first mode, receiving a deactivation indication or a removal indication for data transmission in the first mode, receiving an activation indication or an addition indication for data transmission in the second mode, and receiving a last packet indication or an end marker.

[0041] In some embodiments, the data transmission mode switching occurs without handover, the first cell and the second cell are the same cell, and the first mode and the second mode are different modes.

[0042] In some embodiments, the switching occurs without data transmission mode switching, the first cell and the second cell are different cells, and the first mode and the second mode are the same mode. In addition, in some embodiments, the BS of the first cell and the BS of the second cell can be the same BS or different BSs.

[0043] Figure 3 The signal sequence of the method 100 according to the first embodiment of the present application is described. Figure 3 As shown in FIG, the data transmission mode is switched from the PTM mode to the PTP mode without switching, the first cell and the second cell are the same cell. The first mode is the PTM mode, and the second mode is the PTP mode.

[0044] Please refer to Figure 3 as well as Figure 1 In this embodiment, in step 110, UE 310 receives data packets from BS 320 in PTM mode. A multicast bearer is established for data transmission, and a dedicated bearer associated with the multicast bearer may be established for UE-specific information. Due to a number of reasons, such as degraded radio quality, stricter QoS requirements, and other changing conditions, the network may decide to switch UE 310 to PTP mode for data packet reception.

[0045] Unicast bearers can be configured by the network and can be inactive or active by default and can be activated or deactivated via signaling. To support service continuity and loss-tolerant data transmission, a common sequence number (SN) is shared by both PTP and PTM modes. The common sequence numbering function can be located in the (PDCP) layer or the radio link control (RLC) layer.

[0046] BS 320 sends PTP mode configuration 330 to UE 310, where PTP mode configuration 330 may include signaling for activating PTP mode. UE 310 applies PTP mode configuration 330, and if PTP mode is activated, UE 310 may stop receiving data packets in PTM mode and start receiving data packets in PTP mode, or UE 310 may receive data packets in both PTM mode and PTP mode, and stop receiving data packets in PTM mode upon receiving a last packet indication or end marker via a dedicated bearer associated with the multicast bearer. The PTP mode configuration may be included in a radio resource control (RRC) reconfiguration message, or carried by a media access control element (MAC CE) or downlink control information (DCI).

[0047] In some embodiments, the end marker or last packet indication is in a PDCP control protocol data unit (PDU) or in a header of a PDCP user PDU.

[0048] An example of the last grouping indication is Figure 14 The last packet indication is in the PDCP control PDU and occupies two octets (i.e., Figure 14 The 16-digit number of Oct 2 and Oct 3 shown in Figure 14 In the , “D / C” indicates the “data / control” type, and “R” indicates that the bit is reserved.

[0049] An instance of the closing tag is in Figure 15 The end marker is added in the header of the PDCP User PDU and is shown as "EM". When the end marker indication in the header is detected, the associated packet is the last packet from the PTM mode.

[0050] The end marker or last packet indication may be sent by a MAC CE, in which case the multicast bearer identifier or the unicast bearer identifier is explicitly indicated together with the last packet indication or the end marker.

[0051] During the data transmission mode switch, some data packets may be lost. In step 120, during or after the data transmission mode switch, UE 310 sends a data reception status report 340 to BS 320 via a unicast bearer or a dedicated bearer, for example, when UE 310 stops receiving data in PTM mode (e.g., receives a deactivation indication or removal indication for data transmission in PTM mode). Data reception status report 340 may include the maximum common SN or count value of data packets received in sequence, or a bitmap of received data packet status (i.e., a bitmap indicating which data packets were lost and which data packets were correctly received), or the common SN or count value of the first lost data packet, or a combined data reception status of PTM mode and PTP mode.

[0052] The data reception status report 340 is sent based on at least stopping the reception of data packets in the PTM mode, or receiving a deactivation indication or a removal indication for data transmission in the PTM mode, or receiving an activation indication or an addition indication for data transmission in the PTP mode, or receiving a last packet indication or an end marker.

[0053] To protect lossless data transmission, in step 130 , after receiving the data reception status report 340 , the BS of the first cell (ie, the BS of the second cell) sends lost data packets 350 to the UE 310 via a unicast bearer or a dedicated bearer according to the data reception status report 340 .

[0054] In step 140, UE 310 starts receiving data packets in the first cell in the PTP mode.

[0055] Figure 4 The signal sequence of the method 100 according to the second embodiment of the present application is described. Figure 4 As shown in , the data transmission mode is switched from the PTP mode to the PTM mode without switching, the first cell and the second cell are the same cell, and the first mode is the PTP mode, and the second mode is the PTM mode.

[0056] Please refer to Figure 4 as well as Figure 1 In this embodiment, in step 110, UE 410 receives data packets from BS 420 in PTP mode, establishing an MBS unicast bearer for data transmission. Due to some reasons, such as improved radio quality, relaxed QoS requirements, and other changing conditions, the network may decide to switch UE 410 to PTM mode for data packet reception.

[0057] The network can configure multicast bearers and associated dedicated bearers, and by default, multicast bearers can be inactive or active. Multicast bearers can be activated or deactivated via signaling. To support service continuity and protect against lost data transmission, a common sequence numbering function is shared by both PTP and PTM modes. This common sequence numbering function can reside in either the PDCP layer or the RLC layer.

[0058] BS 420 transmits PTM mode configuration 430 to UE 410, where PTM mode configuration 430 may include signaling for activating PTM mode. UE 410 applies PTM mode configuration 430. If PTM mode is activated, UE 410 may stop receiving data packets in PTP mode and start receiving data packets in PTM mode. Alternatively, UE 410 may receive data packets in both PTM and PTP modes simultaneously and stop receiving data packets in PTP mode after receiving at least all lost data packets, thereby taking into account both data packets in PTP mode and data packets in PTM mode. PTM mode configuration 430 may be included in an RRC reconfiguration message, or may be carried by a MAC CE or DCI.

[0059] During the data transmission mode switching, some data packets may be lost.In step 120, during or after the data transmission mode switching, the UE 410 sends a data reception status report 440 to the BS 420 via a unicast bearer or a dedicated bearer.

[0060] In some embodiments, the UE 410 sends a data reception status report 440 based on at least stopping receiving data packets in the PTP mode, or receiving a deactivation indication or removal indication for data transmission in the PTP mode, or receiving an activation indication or addition indication for data transmission in the PTM mode, or receiving a last packet indication or end marker. The data reception status report 440 may include the maximum common SN of received data packets in the sequence, or a bitmap of received data packet status (the bitmap indicates which data packets were lost and which data packets were correctly received), or the common SN or count value of the first lost data packet, or a combined data reception status of the PTP mode and the PTM mode. In addition, the data reception status report 440 may include at least the minimum common SN or count value of data packets received in the PTM mode.

[0061] To protect lossless data transmission, in step 130 , after receiving the data reception status report 440 , the BS 420 transmits lost data packets 450 to the UE 410 via a unicast bearer or a dedicated bearer according to the data reception status report 440 .

[0062] For example, the smallest received data packet in the PTM mode is data packet #4 (i.e., the smallest common SN or count value is 4), and the UE 410 needs to receive data packets in the PTP mode at least until all data packets before data packet #4 are received, and then the UE 410 can stop receiving data in the PTP mode. In addition, a timer can be configured, and if the timer expires, the UE 410 can stop receiving data packets in the PTP mode, even if all lost data packets before data packet 4 have not been received.

[0063] In step 140, UE 410 starts receiving data packets in PTM mode.

[0064] In some embodiments, the UE switches from the first cell to the second cell without data transmission mode switching, i.e., the first mode and the second mode are the same mode, and the first cell and the second cell are different cells. In step 120, the UE sends a data reception status report to the BS of the second cell during or after the handover.

[0065] Figure 5 The signal sequence of the method 100 according to the third embodiment of the present application is illustrated. A handover from the first cell to the second cell occurs without data transmission mode switching, the first mode and the second mode are the same mode, and the BS of the first cell and the BS of the second cell are the same BS, i.e., BS 520.

[0066] Please refer to Figure 5 as well as Figure 1 In this embodiment, in step 110, initially, UE 510 receives data packets in a first mode in a first cell. If UE 510 moves to a second cell, handover 530 occurs; however, BS 520 decides not to switch the data transmission mode.

[0067] During handover, some data packets may be lost. To support service continuity and protect against lost data transmission, a common sequence numbering function is shared when receiving data packets in the first cell and when receiving data packets in the second cell. The common sequence numbering function can be located in the PDCP layer or the RLC layer.

[0068] When UE 510 moves from a first cell to a second cell, a handover 530 occurs. During the handover 530, some data packets may be lost. To support service continuity and lossless data transmission, in step 120, UE 510 sends a data reception status report 540 associated with a common SN to BS 520. Data reception status report 540 may include the maximum SN of received data packets in a sequence, or a bitmap of received data packet status (the bitmap indicates which data packets were lost and which data packets were correctly received), or the common SN or count value of the first lost data packet, or a combined data reception status in the first cell and in the second cell.

[0069] To protect lossless data transmission, in step 130 , after receiving the data reception status report 540 , the BS 520 transmits lost data packets 550 to the UE 510 via a unicast bearer or a dedicated bearer according to the data reception status report 540 .

[0070] In step 140, after the cell switching, the UE 510 receives data packets in the first mode in the second cell.

[0071] In some embodiments, if the first mode and the second mode are PTM modes, the data reception status report 540 further includes a minimum common SN or count value of data packets received in the PTM mode among all relevant UEs.

[0072] Figure 6 The signal sequence of the method 100 according to the fourth embodiment of the present application is described. Figure 6 As shown in , the handover from the first cell to the second cell occurs without data transmission mode switching, the first mode and the second mode are the same mode, and the BS 620 of the first cell and the BS 630 of the second cell are different BSs.

[0073] Please refer to Figure 6 as well as Figure 1 In this embodiment, in step 110, initially, UE 610 receives data packets in a first cell, whose BS is source BS 620. If UE 510 moves to a second cell, BS 620 sends a handover request to target BS 630 in the second cell, target BS 630 sends a handover request acknowledgment to source BS 620, and then source BS 620 sends a handover command to UE 610. The handover occurs and a connection is established between UE 610 and target BS 630. During the handover procedure, target BS 630 decides not to switch the data transmission mode.

[0074] During the handover procedure, source BS 620 sends MBS reception status 640 to target BS 630 in the handover procedure. MBS reception status 640 includes the service ID of interest to or received by UE 610 and includes the mode type of the first mode. The service ID can be a 5G MBS session ID, a temporary mobile group identifier (TMGI), a multi-radio bearer (MRB) ID, or a unicast data radio bearer (DRB) ID. In some embodiments, MBS reception status 640 can be included in a handover request message. In some embodiments, MBS reception status 640 includes the UE's 5G MBS bearer configuration (e.g., mode type, RRC configuration) in source BS 620.

[0075] In some embodiments, the source BS 620 may send data packets to the target BS 630 during a handoff and / or during a data transmission mode switch.

[0076] During the handover procedure, some data packets may be lost. In step 120, during or after the handover procedure, to support service continuity and lossless data transmission, the UE 610 sends a data reception status report 650 to the target BS 630.

[0077] If the data transmission mode is the PTM mode (ie, the first mode and the second mode are the PTM mode), the data reception status report 650 may further include a minimum common SN or count value of data packets received in the PTM mode.

[0078] In step 130 , the target BS 630 transmits the lost data packet 660 to the UE 610 via a unicast bearer or a dedicated bearer according to the data reception status report 650 .

[0079] To support service continuity and protect against lost data transmission, the data reception status report is associated with a common SN. The common SN is shared when receiving a data packet in a first cell and when receiving a data packet in a second cell.

[0080] In step 140, after the handover procedure, the UE 610 starts receiving data packets in the second cell.

[0081] In some embodiments, the UE switches from a first cell to a second cell, and the data transmission mode for receiving data packets is switched from PTP mode to PTM mode or from PTM mode to PTP mode, that is, the first cell and the second cell are different cells, and the first mode and the second mode are different data transmission modes.

[0082] Figure 7The signal sequence of the method 100 according to the fifth embodiment of the present application is illustrated. A handover from a first cell to a second cell occurs with data transmission mode switching, the first mode and the second mode are different transmission modes, but the BS of the first cell and the BS of the second cell are the same BS 720.

[0083] Please refer to Figure 7 as well as Figure 1 In this embodiment, in step 110, initially, UE 710 receives data packets in a first mode in a first cell. If UE 710 moves to a second cell, handover 730 occurs. BS 720 determines that the data transmission mode of UE 710 in the second cell is a second mode different from the first mode.

[0084] BS 720 sends a mode configuration 740 for the second mode to UE 710. In some embodiments, mode configuration 740 may include signaling for activating / adding the second mode. If the second mode is PTM mode, BS 720 may establish a dedicated bearer associated with the multicast bearer. In some embodiments, the dedicated bearer may be the same as the unicast bearer.

[0085] When the UE 710 moves into the second cell, the UE 710 applies the second mode for data packet reception.During the handover 730 and the data transmission mode switching, some data packets may be lost.

[0086] To support service continuity and protect lost data transmission, in step 120, UE 710 also sends a data reception status report 750 associated with the public SN to BS 720 via a dedicated bearer or a unicast bearer.

[0087] The data reception status report 750 may include the maximum common SN of received data packets in the sequence, or a bitmap of received data packet status (the bitmap indicates which data packets were lost and which data packets were correctly received), or the common SN or count value of the first lost data packet, or the combined data reception status of the first mode and the second mode and / or in the first cell and in the second cell. In addition, if the second mode is the PTM mode, the data reception status report 750 may further include the minimum common SN or count value of data packets received in the second mode. In some embodiments, the data packet may be a PDCP SDU or an RLC SDU. For example, the first lost data packet is the first lost PDCP SDU within the reordering window.

[0088] In step 130 , after the BS 720 receives the data reception status report 750 , the BS 720 transmits the lost data packet 760 to the UE 710 .

[0089] In step 140, after the handover 730 and the data transmission mode switch, the UE 710 receives data packets in the second mode in the second cell.

[0090] Figure 8 The signal sequence of the method 100 according to the sixth embodiment of the present application is described. Figure 8 As shown in FIG, handover from a first cell to a second cell occurs with data transmission mode switching, the first mode and the second mode are different modes, and a source BS 820 of the first cell and a target BS 830 of the second cell are different BSs.

[0091] Please refer to Figure 8 as well as Figure 1 In this embodiment, in step 110, initially, UE 810 receives data packets in a first mode in a first cell, and the BS of the first cell is source BS 820. If UE 810 moves to a second cell, source BS 820 sends a handover request to target BS 830 of the second cell, target BS 830 sends a handover request acknowledgment to source BS 820, and then source BS 820 sends a handover command to UE 810. The handover occurs and a connection between UE 810 and target BS 830 is established.

[0092] During the handover, source BS 820 sends MBS reception status 840 to target BS 830. In some embodiments, MBS reception status 840 is included in the handover request message. MBS reception status 840 may include the service ID of the service that UE 810 is interested in or receiving, and the mode type of the first mode. The service ID may be a 5G MBS session ID, a TMGI, an MRB ID, or a unicast DRB ID. In some embodiments, MBS reception status 840 includes the UE's 5G MBS bearer configuration (e.g., mode type, RRC configuration) in source BS 820.

[0093] In some embodiments, the source BS 820 may send data packets to the target BS 830 during a handoff and / or during a data transmission mode switch.

[0094] Furthermore, target BS 830 determines that the data transmission mode in the second cell is a second mode different from the first mode. Target BS 830 sends a mode configuration 850 for the second mode to UE 810. Mode configuration 850 may include signaling for activating / adding the second mode. UE 810 applies mode configuration 850. Furthermore, if the second mode is PTM mode, a dedicated bearer associated with the multicast bearer of the second mode is established. In some embodiments, the dedicated bearer may be the same as a unicast bearer.

[0095] During the handover procedure, some data packets may be lost. In step 120, after accessing the target BS 830, the UE 810 sends a data reception status report 860 to the target BS 830 via a unicast bearer or a dedicated bearer. In step 130, the target BS 830 sends the lost data packets 870 to the UE 810 via a unicast bearer or a dedicated bearer based on the data reception status report 650.

[0096] To support service continuity and protect against lost data transmission, the data reception status report is associated with a common SN. The common SN is shared by the first mode and the second mode, and is shared in the first cell and the second cell.

[0097] In step 140, after the handover procedure and the data transmission mode switching, the UE 810 receives data packets in the second cell in the second mode.

[0098] In some embodiments, in step 120, if the UE stops receiving data packets from the first cell in the first mode, the UE sends a data reception status report.

[0099] In some embodiments, in step 120, if the UE receives a deactivation indication or a removal indication of data transmission in the first mode, the UE sends a data reception status report.

[0100] In some embodiments, in step 120, if the UE receives an activation indication or an addition indication for data transmission in the second mode, the UE sends a data reception status report.

[0101] In some embodiments, in step 120, if the UE receives a last packet indication or an end marker from the BS of the first cell, the UE sends a data reception status report.

[0102] Figure 9 A block diagram illustrates a UE 900 according to an embodiment of the present disclosure. UE 900 may include receive circuitry, a processor, and transmit circuitry. In one embodiment, the UE may include: a non-transitory computer-readable medium having computer-executable instructions stored thereon; receive circuitry; transmit circuitry; and a processor coupled to the non-transitory computer-readable medium, receive circuitry, and transmit circuitry. The computer-executable instructions may be programmed to use the receive circuitry, transmit circuitry, and processor to implement the steps of method 100 described above.

[0103] Figure 10An exemplary RAN-based method 1000 for MBS performed by a BS to transmit data packets to a UE when data transmission mode switching and / or handover occurs under the same BS (i.e., a first cell is different from a second cell, but the BS of the first cell and the BS of the second cell are the same BS) is described.

[0104] As in Figure 10 As shown in FIG, method 1000 may include step 1010 of transmitting data packets in a first cell in a first mode, step 1020 of receiving a data reception status report during or after switching from the first cell to the second cell and / or during or after switching the data transmission mode from the first mode to the second mode, step 1030 of transmitting lost data packets according to the data reception status report, and step 140 of transmitting data packets in the second cell in a second mode.

[0105] In some embodiments, each of the first mode and the second mode is one of the PTP mode and the PTM mode and is associated with the first bearer and the second bearer, respectively, wherein each of the first bearer and the second bearer can support both the first mode and the second mode.

[0106] In some embodiments, each of the first bearer and the second bearer is one of a multicast bearer for data transmission in PTM mode and a unicast bearer for data transmission in PTP mode. In some embodiments, the multicast bearer is scrambled by a group radio network temporary identifier (G-RNTI) in at least one cell, and the unicast bearer is scrambled by a cell radio network temporary identifier (C-RNTI).

[0107] Since multicast bearers are cell- or multicast area-specific, it is inappropriate to use multicast bearers to transmit or receive UE-specific information. Therefore, in some embodiments, a dedicated bearer associated with the multicast bearer is established for transmitting UE-specific information (e.g., a reception status report) or for receiving a last packet indication or end marker for stopping the data transmission mode. In some embodiments, the dedicated bearer can be the same as the unicast bearer.

[0108] In some embodiments, the BS triggers the UE to send a data reception status report by at least stopping transmitting data packets in the first mode, or transmitting a deactivation indication or a removal indication of data transmission in the first mode, or transmitting an activation indication or an addition indication of data transmission in the second mode, or transmitting a last packet indication or an end marker.

[0109] In some embodiments, the BS receives the data reception status report via a dedicated bearer or a unicast bearer, and transmits the lost data packet via the dedicated bearer or the unicast bearer.

[0110] In some embodiments, the BS transmits a last packet indication or an end marker to the UE via a dedicated bearer or a unicast bearer.

[0111] In some embodiments, the BS transmits a deactivation indication or a removal indication of data transmission in the first mode via a dedicated bearer or a unicast bearer.

[0112] In some embodiments, the BS transmits an activation indication or an addition indication of data transmission in the first mode via a dedicated bearer or a unicast bearer.

[0113] In some embodiments, the BS deactivates or removes data transmission in the first mode by transmitting all lost data packets or upon expiration of a configured timer. For example, the BS may configure a timer such that upon expiration of the timer, the BS triggers the UE to stop receiving data packets in the first mode, even if all lost data packets have not been transmitted to the UE.

[0114] Figure 11 An exemplary RAN-based method 1100 for MBS performed by a source BS when a handover to a target BS occurs with / without data transmission mode switching is illustrated. Figure 11 As shown in FIG, the method 1100 may include a step 1110 of transmitting data packets in a first mode in a first cell, a step 1120 of sending an MBS reception status to a target base station BS during handover, wherein the MBS reception status may include a service ID associated with data reception and include a type of data transmission mode, and a step 1130 of stopping transmitting data packets in the first mode in the first cell.

[0115] In some embodiments, the source BS may send data packets during the handover and / or during the switching of data transmission mode to the target BS.

[0116] In some embodiments, the lost data packets comprise data packets lost during the switching, and if a data transmission mode switching also occurs, the lost data packets comprise data packets lost during the data transmission mode switching.

[0117] In some embodiments, the MBS reception status is included in the handover request message.

[0118] In some embodiments, in step 1140, the source BS may send a last packet indication or an end marker to deactivate the first mode.

[0119] In some embodiments, the lost data packets and the last packet indication or end marker may be transmitted via a dedicated bearer if the first mode is PTM mode, or via a dedicated bearer or a unicast bearer if the first mode is PTP mode.

[0120] Figure 12 An exemplary RAN-based method 1200 for MBS performed by a target BS when a handover occurs from a source BS with / without data transmission mode switching is illustrated.

[0121] As in Figure 12 As shown in FIG. 1 , in step 1210, a UE receives data packets in a first mode in a first cell, where the base station (BS) of the first cell is a source BS. If the UE moves to a second cell under a target BS, the target BS receives an MBS reception status from the source BS during a handover procedure. In some embodiments, the MBS reception status is included in a handover request message. The MBS reception status includes at least a service ID associated with data transmission in the first mode and the type of the first mode.

[0122] In step 1220, the target BS determines that the UE receives data packets in the second mode in the second cell and sends a corresponding mode configuration to the UE. In some embodiments, even if the second mode is the same as the first mode, the target BS still sends the corresponding mode configuration to the UE.

[0123] In step 1230, the target BS receives a data reception status report during or after the handover and / or during or after the data transmission mode is switched from the first mode to the second mode. The data reception status report is associated with a common SN, and the common SN is shared by the source BS and the target BS and is shared by the first mode and the second mode.

[0124] In step 1240, the target BS transmits the lost data packets to the UE according to the data reception status report.

[0125] In step 1250, the target BS transmits data packets to the UE in the second cell in the second data transmission mode.

[0126] In some embodiments, the first mode and the second mode are the same mode.

[0127] In some embodiments, the source BS may send data packets during the handover and / or during the switching of data transmission mode to the target BS.

[0128] In some embodiments, if the second mode is PTM mode, the target BS may establish a dedicated bearer associated with the multicast bearer for UE-specific information (e.g., data reception status reports or lost data packets). In some embodiments, the target BS may receive data reception status reports via a unicast bearer or a dedicated bearer, and may transmit lost data packets via a unicast bearer or a dedicated bearer. In some embodiments, the dedicated bearer and the unicast bearer are the same bearer.

[0129] Figure 13A block diagram illustrates a base station (BS) 1300 that performs method 1000, method 1100, or method 1200. BS 1300 may include receive circuitry, a processor, and transmit circuitry. In one embodiment, a user equipment (UE) may include a non-transitory computer-readable medium having computer-executable instructions stored thereon; receive circuitry; transmit circuitry; and a processor coupled to the non-transitory computer-readable medium, receive circuitry, and transmit circuitry. The computer-executable instructions may be programmed to use the receive circuitry, transmit circuitry, and processor to implement the steps shown in methods 1000, 1100, or 1200 mentioned above.

[0130] The order of the steps mentioned in the above embodiments can be adjusted within a reasonable range and is not intended to limit the present invention.

[0131] On the basis of not violating the principles of the present disclosure and on the premise that there is no conflict with each other, the steps of the above-mentioned embodiments can be reasonably combined as needed.

[0132] The methods of the present invention may be implemented on a programmed processor. However, the controller, flow charts, and modules may also be implemented on a general-purpose or special-purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit components, an integrated circuit, hardware electronic or logic circuits (e.g., discrete element circuits), a programmable logic device, or the like. In general, any device having a finite state machine capable of implementing the flow charts shown in the figures may be used to implement the processing functions of the present invention.

[0133] Although the present invention has been described using specific embodiments thereof, it is apparent that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, in other embodiments, the various components of the embodiments may be interchangeable, added, or replaced. Furthermore, not all elements of each figure are required for the operation of the disclosed embodiments. For example, those skilled in the art of the disclosed embodiments will be able to make and use the teachings of the present invention by simply adopting the elements of the independent claims. Therefore, the embodiments of the present invention set forth herein are intended to be illustrative, not restrictive. Various changes may be made without departing from the spirit and scope of the present invention.

[0134] In the present disclosure, for example, the relational terms of "first", "second" can only be used to distinguish an entity or action from another entity or action, without requiring or implying any actual this relationship or order between this entity or action. The term "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements not only comprise the elements, but also can comprise other elements that are not clearly listed or inherent to this process, method, article or equipment. Without more constraints, the elements starting with "one" or the like do not exclude the presence of additional equivalent elements in the process, method, article or equipment comprising the elements. In addition, the term "another" is defined as at least second or more. The terms "comprise", "have" and the like used herein are defined as "comprise".

Claims

1. A user equipment (UE) for wireless communication, the UE comprising at least one processor configured to cause the UE to: receiving a data packet in a first transmission mode in a first cell; sending a data reception status report during or after a handover from the first cell to the second cell or during or after a data transmission mode switch from the first transmission mode to the second transmission mode, one of the first transmission mode and the second transmission mode being a point-to-point (PTP) mode and the other of the first transmission mode and the second transmission mode being a point-to-multipoint (PTM) mode; receiving lost data packets after or during said data transmission mode switch or after or during said switch; as well as Data packets are received in the second cell or in the second transmission mode.

2. The UE of claim 1 , wherein the at least one processor is configured to cause the UE to send the data reception status report based on at least: stop receiving data packets in the first transmission mode; or receiving a deactivation indication or a removal indication for data transmission in the first transmission mode; or receiving an activation indication or an addition indication for the data transmission in the second transmission mode; or The last packet indication or end marker is received.

3. The UE according to claim 1, wherein the data reception status report includes a common sequence number (SN), and the common SN is shared by the first transmission mode and the second transmission mode or shared by the first cell and the second cell. The UE according to claim 3 , wherein a first bearer and a second bearer are associated with the first transmission mode and the second transmission mode, respectively. The UE according to claim 4 , wherein each of the first bearer and the second bearer supports the first transmission mode and the second transmission mode.

6. The UE according to claim 4, wherein the data reception status report comprises at least one of the following: a maximum SN or count value for data packets received in said first transmission mode; a bitmap indicating which data packets were lost and which were received correctly; SN or count value of the first lost data packet; as well as for the first transmission mode and the second transmission mode and / or for a combined data reception status in the first cell and the second cell. 7 . The UE according to claim 6 , wherein in response to the second transmission mode being the PTM mode, the data reception status report further includes at least a minimum SN or a count value for data packets received in the second transmission mode. The UE according to claim 4 , wherein the data reception status report is sent via a dedicated bearer or a unicast bearer. 9 . The UE of claim 4 , wherein the lost data packet is received via a dedicated bearer or a unicast bearer.

10. The UE of claim 4, wherein the at least one processor is configured to cause the UE to: The first bearer or the first transmission mode is deactivated or removed when a last packet indication or an end marker is received via a dedicated bearer or a unicast bearer.

11. The UE of claim 4, wherein the at least one processor is configured to cause the UE to: The first bearer or the first transmission mode is deactivated or removed when all the lost data packets are received or a configured timer expires.

12. The UE according to claim 4, wherein a multicast bearer is used for data transmission in the PTM mode, the multicast bearer is scrambled by a group radio network temporary identifier (G-RNTI) in at least one cell, and a unicast bearer is used for data transmission in the PTP mode, the unicast bearer is scrambled by a cell radio network temporary identifier (C-RNTI).

13. A base station (BS) for wireless communication, the base station comprising at least one processor configured to cause the BS to: transmitting data packets to a user equipment UE in a first transmission mode; receiving a data reception status report from the UE during or after handover from a first cell to a second cell or during or after data transmission mode switch from the first transmission mode to a second transmission mode, one of the first transmission mode and the second transmission mode being a point-to-point (PTP) mode and the other of the first transmission mode and the second transmission mode being a point-to-multipoint (PTM) mode; transmitting lost data packets to the UE during or after the data transmission mode switch or during or after the switch according to the data reception status report; as well as Data packets are transmitted to the UE in the second cell or in a second transmission mode.

14. The BS of claim 13 , wherein the at least one processor is configured to cause the BS to trigger the UE to send the data reception status report based on at least: Stop transmitting data packets in the first transmission mode; or receiving a deactivation indication or a removal indication for data transmission in the first transmission mode; or receiving an activation indication or an addition indication for the data transmission in the second transmission mode; or Transmission last packet indication or end marker.

15. The BS according to claim 13, wherein the data reception status report includes a common sequence number (SN), and the common SN is shared by the first transmission mode and the second transmission mode and / or shared by the first cell and the second cell. 16 . The BS according to claim 15 , wherein the first transmission mode and the second transmission mode are one of a PTP mode and a PTM mode, and a first bearer and a second bearer are associated with the first transmission mode and the second transmission mode, respectively. The BS of claim 16 , wherein each of the first bearer and the second bearer supports the first transmission mode and the second transmission mode.

18. The BS according to claim 16, wherein the data reception status report includes at least one of: a maximum SN or a count value for data packets transmitted to the UE in the first transmission mode; a bitmap indicating which data packets were lost and which packets were correctly received by the UE; SN or count value of the first lost data packet; as well as A combined data reception status for the first transmission mode and the second transmission mode and / or for the UE in the first cell and the second cell.

19. The BS according to claim 17, wherein in response to the second transmission mode being the PTM mode, the data reception status report further includes at least a minimum common SN or a count value for data packets received in the second transmission mode.

20. The BS of claim 16, wherein the data reception status report is received via a dedicated bearer or a unicast bearer.

21. The BS of claim 16, wherein the lost data packet is transmitted via a dedicated bearer or a unicast bearer.

22. The BS of claim 16, wherein the at least one processor is configured to cause the BS to: A last packet indication or an end marker is transmitted via a dedicated bearer or a unicast bearer for deactivating or removing the first bearer.

23. The BS of claim 16, wherein the at least one processor is configured to cause the BS to: The first bearer or the first transmission mode is deactivated or removed when all the lost data packets are transmitted or a configured timer expires.

24. The BS of claim 16, wherein a multicast bearer is used for data transmission in the PTM mode and the multicast bearer is scrambled by a group radio network temporary identifier (G-RNTI) in at least one cell, and a unicast bearer is used for data transmission in the PTP mode and the unicast bearer is scrambled by a cell radio network temporary identifier (C-RNTI).

25. A method performed by a user equipment (UE), the method comprising: receiving a data packet in a first transmission mode in a first cell; sending a data reception status report during or after a handover from the first cell to the second cell or during or after a data transmission mode switch from the first transmission mode to the second transmission mode, one of the first transmission mode and the second transmission mode being a point-to-point (PTP) mode and the other of the first transmission mode and the second transmission mode being a point-to-multipoint (PTM) mode; receiving lost data packets after or during said data transmission mode switch or after or during said switch; as well as Data packets are received in the second cell or in the second transmission mode.

26. A method performed by a base station, the method comprising: transmitting data packets to a user equipment UE in a first transmission mode; receiving a data reception status report from the UE during or after handover from a first cell to a second cell or during or after data transmission mode switch from the first transmission mode to a second transmission mode, one of the first transmission mode and the second transmission mode being a point-to-point (PTP) mode and the other of the first transmission mode and the second transmission mode being a point-to-multipoint (PTM) mode; transmitting lost data packets to the UE during or after the data transmission mode switch or during or after the switch according to the data reception status report; as well as Data packets are transmitted to the UE in the second cell or in the second transmission mode.

27. A non-transitory computer-readable medium having computer-executable instructions stored thereon, wherein a processor executes the instructions to implement the method of claim 25 or 26.

Images