EP4595474A1

EP4595474A1 - Methods and apparatuses of supporting continuity of mrb

Info

Publication number: EP4595474A1
Application number: EP23874172.2A
Authority: EP
Inventors: Mingzeng Dai; Congchi ZHANG; Lianhai WU; Xiaoying Xu; Haiyan Luo
Original assignee: Lenovo Beijing Ltd
Current assignee: Lenovo Beijing Ltd
Priority date: 2023-01-17
Filing date: 2023-01-17
Publication date: 2025-08-06
Also published as: WO2024073976A1; EP4595474A4; GB202506646D0; CN120202685A; GB2639431A

Abstract

The present application relates to methods and apparatuses of supporting continuity of a multicast radio bearer (MRB). One embodiment of the present disclosure provides a user equipment (UE) which includes: a transceiver; and a processor coupled with the transceiver and configured to: receive, via the transceiver, information associated with packet data convergence protocol (PDCP) of an MRB via a radio resource control (RRC) dedicated signaling, wherein the PDCP includes one or more PDCP variables; transition to an RRC non-connected state; and determine, based on the information associated with the PDCP of the MRB, whether to use the one or more PDCP variables for continuity of the MRB while the UE is in the RRC non-connected state.

Description

METHODS AND APPARATUSES OF SUPPORTING CONTINUITY OF MRB

TECHNICAL FIELD

The present disclosure relates to wireless communication, and particularly relates to methods and apparatuses of supporting continuity of a multicast multicast/broadcast services (MBS) radio bearer (MRB) .
BACKGROUND OF THE DISCLOSURE
Multicast reception by user equipment (UE) in a radio resource control (RRC) non-connected state, such as an RRC inactive state, or an RRC idle state, is supported. A MBS control channel (MCCH) may be used for providing the point-to-multipoint (PTM) configuration for UEs to receive multicast in the RRC non-active state, in the case that there is a need to indicate a PTM configuration, or there is a change of PTM configuration or during mobility beyond serving cell or a base station (BS) . Currently, the MCCH may be provided per cell for broadcast service only. MCCH may only support an MRB add list and an MRB release list. That is, there is no MRB modification list due to delta configuration is not possible because the PTM configuration among different cells may be different.
Therefore, it is advantageous to provide methods and apparatuses of supporting continuity of the multicast MRB.
SUMMARY
An embodiment of the present disclosure provides a UE which includes: a transceiver; and a processor coupled with the transceiver and configured to: receive, via the transceiver, information associated with packet data convergence protocol (PDCP) of an MRB via an RRC dedicated signaling, wherein the PDCP includes one or more PDCP variables; transition to an RRC non-connected state; and determine, based on the information associated with the PDCP of the MRB, whether to use the one or more PDCP variables for continuity of the MRB while the UE is in the RRC non-connected state.
In some embodiments, the information associated with PDCP of the MRB includes an area or a list of cells in which continuity of the MRB is supported.
In some embodiments, the processor is further configured to: perform cell reselection from a first cell to a second cell; and use the one or more PDCP variables for continuity of the MRB in the case that the first cell and the second cell are within the area or in the list of cells.
In some embodiments, the processor is configured to: release a first radio link control (RLC) bearer of the MRB in the first cell when leaving the first cell; acquire an RLC bearer configuration of the MRB via an MCCH in the second cell when entering the second cell; and establish a second RLC bearer of the MRB in the second cell according to the RLC bearer configuration of the MRB.
In some embodiments, the information associated with the PDCP of the MRB indicates an identity (ID) of a first RLC bearer in the first cell, and the processor is further configured to: associate a same PDCP entity in the first cell with the second RLC bearer in the second cell in the case that a same ID of the second RLC bearer is also received via the MCCH in the second cell.
In some embodiments, the information associated with the PDCP of the MRB indicates a first ID of the MRB in the first cell and a second ID of the MRB in the second cell, and wherein the processor is further configured to: associate the MRB in the second cell with a PDCP entity of the MRB in the first cell.
In some embodiments, the information associated with the PDCP of the MRB indicates one or more indexes of PDCP configurations.
In some embodiments, the one or more indexes include a first index of a PDCP configuration, and the processor is further configured to: perform cell reselection from a first cell to a second cell; receive a second index of a PDCP configuration in the second cell from an MCCH; and use the one or more PDCP variables for continuity of the MRB in the case that the first index and second index are identical.
In some embodiments, the information associated with PDCP of the MRB further includes a corresponding PDCP configuration for each index.
In some embodiments, the corresponding PDCP configuration for each index is pre-defined.
In some embodiments, in order to use the one or more PDCP variables for continuity of the MRB, the processor is further configured to: store the one or more PDCP variables of a PDCP entity of the MRB used in the first cell; release the PDCP entity of the MRB and establish a new PDCP entity of a new MRB in the second cell; and set one or more PDCP variables of the new PDCP entity of the new MRB with the one or more PDCP variables of the PDCP entity as stored.
In some embodiments, in order to use the one or more PDCP variables for continuity of the MRB, the processor is further configured to: keep a same PDCP entity of the MRB in the second cell; and continue to use latest PDCP variables of the PDCP entity of the MRB in the second cell.
In some embodiments, in order to use the one or more PDCP variables for continuity of the MRB, the processor is further configured to: reestablish the PDCP entity of the MRB in the second cell; and continue to use the latest PDCP variables of the PDCP entity of the MRB in the second cell.
In some embodiments, the processor is further configured to: trigger a PDCP status report and an RRC resume procedure in the second cell in the case that a PDCP variable of a first received packet in the second cell is larger or smaller than a corresponding stored PDCP variable by a threshold.
Another embodiment of the present disclosure provides a BS which includes: a transceiver; and a processor coupled with the transceiver and configured to: determine information associated with PDCP of an MRB, wherein the PDCP includes one or more PDCP variables; and transmit, via the transceiver, the information associated with PDCP of the MRB to a UE via an RRC dedicated signaling.
In some embodiments, the information associated with the PDCP of the MRB includes an area or a list of cells in which continuity of the MRB is supported.
In some embodiments, the information associated with the PDCP of the MRB indicates an ID of an RLC bearer in the first cell.
In some embodiments, the information associated with the PDCP of the MRB indicates a first ID of the MRB in the first cell and a second ID of the MRB in a second cell.
In some embodiments, the information associated with the PDCP of the MRB indicates one or more indexes of PDCP configurations.
In some embodiments, the one or more indexes include a first index of a PDCP configuration in the first cell.
In some embodiments, the BS includes a central unit (CU) and a distributed unit (DU) , the CU is configured to determine the information associated with the PDCP of the MRB and transmit the information associated with the PDCP of the MRB to the DU.
Another embodiment of the present disclosure provides a method performed by a UE which includes: receiving information associated with PDCP of an MRB via an RRC dedicated signaling, wherein the PDCP includes one or more PDCP variables; transitioning to an RRC non-connected state; and determining, based on the information associated with the PDCP of the MRB, whether to use the one or more PDCP variables for continuity of the MRB while the UE is in the RRC non-connected state.
Yet another embodiment of the present disclosure provides a method performed by a BS which includes: determining information associated with PDCP of an MRB, wherein the PDCP includes one or more PDCP variables; and transmitting the information associated with PDCP of the MRB as determined to a UE via an RRC dedicated signaling.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which advantages and features of the application can be obtained, a description of the application is rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. These drawings depict only example embodiments of the application and are not therefore to be considered limiting of its scope.
Fig. 1 illustrates a schematic diagram of a wireless communication system according to some embodiments of the present disclosure.
Fig. 2 illustrates a method performed by a UE for wireless communication according to some embodiments of the present disclosure.
Fig. 3 illustrates a method performed by a BS for wireless communication according to some embodiments of the present disclosure.
Fig. 4 illustrates a per area PDCP and a per cell RLC or low layer for an MRB according to some embodiments of the present disclosure.
Fig. 5 illustrates a flow chart of supporting continuity of an MRB according to some embodiments of the present disclosure.
Fig. 6 illustrates a flow chart of supporting continuity of an MRB according to some embodiments of the present disclosure.
Fig. 7 illustrates a simplified block diagram of an apparatus according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

The detailed description of the appended drawings is intended as a description of the currently preferred embodiments of the present invention, and is not intended to represent the only form in which the present invention may be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present invention.
While operations are depicted in the drawings in a particular order, persons skilled in the art will readily recognize that such operations need not be performed in the particular order as shown or in a sequential order, or that all illustrated operations need be performed, to achieve desirable results; sometimes one or more operations can be skipped. Further, the drawings can schematically depict one or more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing can be advantageous.
Reference will now be made in detail to some embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architecture and new service scenarios, such as a cellular telephone 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, a LTE network, a 3^rd generation partnership project (3GPP) -based network, LTE, LTE-Advanced (LTE-A) , 3GPP 4G, 3GPP 5G NR, 3GPP Release 16 and onwards, a satellite communications network, a high altitude platform network, and so on. It is contemplated that along with the developments of network architectures and new service scenarios, all embodiments in the present disclosure are also applicable to similar technical problems; and moreover, the terminologies recited in the present disclosure may change, which should not affect the principle of the present disclosure.
Fig. 1 illustrates a schematic diagram of a wireless communication system according to some embodiments of the present disclosure.
As shown in Fig. 1, the wireless communication system includes UE 101, BS 102-A, base station 102-B, and base station 102-C. Even though a specific number of UE and BSs are depicted in Fig. 1, person skilled in the art will recognize that any number of UEs and BSs may be included in the wireless communication system.
The UE 101 may 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) , vehicle on-board computers, network devices (e.g., routers, switches, modems) , or the like. According to an embodiment of the present disclosure, the UE 101 may include a portable wireless communication device, a smart phone, a cellular telephone, a flip phone, a device having a subscriber identity module, a personal computer, a selective call receiver, or any other device that is capable of sending and receiving communication signals on a wireless network. In some embodiments, the UE 101 includes wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like. Moreover, the UE 101 may be referred to as subscriber units, mobiles, mobile stations, users, terminals, mobile terminals, wireless terminals, fixed terminals, subscriber stations, UE 101, user terminals, a device, or by other terminology used in the art. The UE 101 may communicate directly with a BS via uplink (UL) communication signals.
The BSs may be distributed over a geographic region. In certain embodiments, a BS may also be referred to as an access point, an access terminal, a base, a base station, a macro cell, a Node-B, an enhanced Node B (eNB) , a BS, a Home Node-B, a relay node, a device, or by any other terminology used in the art. The BSs are generally part of a radio access network that may include one or more controllers communicably coupled to one or more corresponding BSs.
The wireless communication system is compliant with any type of network that is capable of sending and receiving wireless communication signals. For example, the wireless communication system is compliant with a wireless communication network, a cellular telephone 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, a LTE network, a 3GPP-based network, 3GPP 5G network, a satellite communications network, a high altitude platform network, and/or other communications networks.
In an implementation, the wireless communication system is compliant with the NR of the 3GPP protocol, wherein the BS transmits using an orthogonal frequency division multiplexing (OFDM) modulation scheme on the DL and the UE 101 transmits on the uplink using a single-carrier frequency division multiple access (SC-FDMA) scheme or OFDM scheme. More generally, however, the wireless communication system may implement some other open or proprietary communication protocol, for example, WiMAX, among other protocols.
In other embodiments, the BS may communicate using other communication protocols, such as the IEEE 802.11 family of wireless communication protocols. Further, in some embodiments the BS may communicate over licensed spectrum, while in other embodiments the BS may communicate over unlicensed spectrum. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol. In another embodiment, the BS may communicate with UE 101 using the 3GPP 5G protocols.
As shown in Fig. 1, the UE 101 is currently located in cell 1, and may be in an RRC non-connected state, such as an RRC inactive state. The UE may receive the MBS service in the RRC inactive state, and may reselect cell 2 and enter cell 2.
Currently, the MRB served by cell 1 may be released, and a new MRB may be established in the cell 2:
- for broadcast, the MRB is released upon leaving the cell broadcasting the MBS session the UE is interested in.
- for broadcast, the MRB is established upon entering a cell providing an MBS broadcast service the UE is interested in.
Then current MCCH scheme cannot support service continuity when UE moves to a neighbor cell. Different from broadcast service, multicast service needs high reliability and service continuity. The present disclosure proposes some solutions for supporting mobility and service continuity by the MCCH for multicast reception for a UE in an RRC non-connected state when the UE moves from a cell to another cell. More specifically, solutions for supporting continuity of an MRB for multicast service.
Fig. 2 illustrates a method performed by a UE for wireless communication according to some embodiments of the present disclosure.
In operation 201, the UE may receive, via the transceiver, information associated with PDCP of an MRB via an RRC dedicated signaling, wherein the PDCP may include one or more PDCP variables, such as RX_NEXT, RX_DELIV, or the like. In operation 202, the UE may transition to an RRC non-connected state, e.g., RRC inactive state. In operation 203, the UE may determine, based on the information associated with the PDCP of the MRB, whether to use the one or more PDCP variables for continuity of the MRB while the UE is in the RRC non-connected state.
In some embodiments, the information associated with PDCP of the MRB includes an area or a list of cells in which continuity of the MRB is supported. For example, an area including cell 1, cell 2, and cell 3 as shown in Fig. 1, or a list of cells including cell 1, cell 2, and cell 3 as shown in Fig. 1.
In some embodiments, the UE may perform cell reselection from a first cell to a second cell; and may use the one or more PDCP variables for continuity of the MRB in the case that the first cell and the second cell are within the area or in the list of cells.
In some embodiments, the UE may release a first RLC bearer of the MRB in the first cell when leaving the first cell; acquire an RLC bearer configuration of the MRB via an MCCH in the second cell when entering the second cell; and establish a second RLC bearer of the MRB in the second cell according to the RLC bearer configuration of the MRB.
In some embodiments, the information associated with the PDCP of the MRB indicates an ID of a first RLC bearer in the first cell, and the UE may associate the same PDCP entity in the first cell with the second RLC bearer in the second cell in the case that the same ID of the second RLC bearer is also received via the MCCH in the second cell.
In some embodiments, the information associated with the PDCP of the MRB indicates a first ID of the MRB in the first cell (for example, MRB #1) and a second ID of the MRB in the second cell (for example, MRB #2) , and the UE may associate the MRB in the second cell (for example, MRB #2) with a PDCP entity of the MRB in the first cell (for example, MRB #1) .
In some embodiments, the information associated with the PDCP of the MRB indicates one or more indexes of PDCP configurations. For example, index 1: PDCP configuration 1; index 1: PDCP configuration 2; …, etc.
In some embodiments, the one or more indexes include a first index of a PDCP configuration, and the UE may perform cell reselection from a first cell to a second cell, receive a second index of a PDCP configuration in the second cell from an MCCH, and use the one or more PDCP variables for continuity of the MRB in the case that the first index and second index are identical. For example, PDCP configuration 1 and PDCP configuration 2 have the same index, e.g., index 1, thus, the UE may use the one or more PDCP variables for continuity of the MRB in the second cell.
In some embodiments, the information associated with PDCP of the MRB further includes a corresponding PDCP configuration for each index. For example, the MCCH also indicates PDCP configuration 1 for index 1. In some embodiments, the corresponding PDCP configuration for each index is pre-defined.
In some embodiments, in order to use the one or more PDCP variables for continuity of the MRB, the UE may store the one or more PDCP variables of a PDCP entity of the MRB used in the first cell; release the PDCP entity of the MRB and establish a new PDCP entity of a new MRB in the second cell; and set one or more PDCP variables of the new PDCP entity of the new MRB with the one or more PDCP variables of the PDCP entity as stored. For example, the latest values of PDCP variables for the PDCP entity in the first cell such as RX_NEXT, RX_DELIV, or the like, are stored. After establishing the new PDCP entity, values of the PDCP variables for the new PDCP entity are set to the stored values of the PDCP variables.
In some embodiments, in order to use the one or more PDCP variables for continuity of the MRB, the UE may keep the same PDCP entity of the MRB in the second cell, and continue to use latest PDCP variables of the PDCP entity of the MRB in the second cell. In some embodiments, in order to use the one or more PDCP variables for continuity of the MRB, the UE may reestablish the PDCP entity of the MRB in the second cell, and continue to use the latest PDCP variables of the PDCP entity of the MRB in the second cell.
In some embodiments, the UE may trigger a PDCP status report and an RRC resume procedure in the second cell in the case that a PDCP variable of a first received packet in the second cell is larger or smaller than a corresponding stored PDCP variable by a threshold.
Fig. 3 illustrates a method performed by a BS for wireless communication according to some embodiments of the present disclosure.
In operation 301, the BS may determine information associated with PDCP of an MRB, wherein the PDCP may include one or more PDCP variables; and in operation 302, the BS may transmit, via the transceiver, the information associated with PDCP of the MRB to a UE via an RRC dedicated signaling.
In some embodiments, the BS may include a CU and a DU, wherein the CU is configured to determine the information associated with the PDCP of the MRB and transmit the information associated with the PDCP of the MRB to the DU.
Fig. 4 illustrates a per area PDCP and a per cell RLC or low layer for an MRB according to some embodiments of the present disclosure.
In Fig. 4, there may be three cells, e.g., cell 1, cell 2, and cell 3. The PDCP entity of the MRB is per area. The RLC bearer associated with the PDCP entity is per cell, and accordingly, there are three RLC bearers, e.g., RLC bearer 1, RLC bearer 2, and RLC bearer 3. Each RLC bearer of the MRB may include an RLC entity, and other lower layer entity (a medium access control (MAC) entity and a physical (PHY) entity) of the MRB. RLC bearer 1 may be associated with a group radio network temporary identifier (G-RNTI) , e.g., G-RNTI 1 in cell 1, RLC bearer 2 may be associated with G-RNTI 2 in cell 2, and RLC bearer 3 may be associated with G-RNTI 3 in cell 3.
In order to support service continuity between cells for PTM reception for a UE in the RRC non-connected state, e.g., RRC idle state or RRC inactive state, the PDCP of an MRB may be continuous within a certain area. The present disclosure proposes some solutions for supporting service continuity using one or more PDCP variables for continuity of the MRB.
The PDCP variables may at least include the following: 1) RX_NEXT; and 2) RX_DELIV. The first variable, e.g., RX_NEXT, may indicate a count value (e.g., a currently received latest count value plus 1) of a next PDCP service data unit (SDU) or protocol data unit (PDU) that is expected to be received. The second variable, e.g., RX_DELIV, may indicate a count value of an SDU or a PDU that is still waiting and is the first SDU or PDU that is not delivered to an upper layer. In some other embodiments, other PDCP variables may also be applied.
The present disclosure proposes that when the UE moves within the area (i.e. the UE may perform a cell reselection procedure from an old cell to a new cell, and both the old cell and the new cell are within the area) in which continuity of the MRB is supported, the UE may use the one or more PDCP variables for continuity of the MRB, more specifically, the following options may be taken:
- Option 1: the PDCP entity may be kept, in other words, the PDCP entity may not be released or re-established. Since the PDCP entity is not released or re-established as the UE moving within the area, the PDCP variables (e.g., RX_NEXT and RX_DELIV) are continuous. Thus, continuity of the MRB is achieved.
- Option 2: an old PDCP entity served by the old cell (the cell before cell reselection) may be released, and the latest PDCP variables of an old PDCP entity may be stored when releasing the old PDCP entity. After establishing a new PDCP entity in the new cell (the cell after cell reselection) , the initial values of the PDCP variables of the new PDCP entity may be configured with the stored PDCP variables of the old PDCP entity used in the old cell. In this way, the PDCP variables are continuous and continuity of the MRB is achieved. Release of the old PDCP entity can be achieved by release of the old MRB. Establishment of the new PDCP entity can be achieved by establishing of a new MRB in the new cell.
- Option 3: the PDCP entity may be re-established (e.g., an old PDCP entity used in an old cell is re-established) , and the PDCP variables of the PDCP entity may be kept, more specifically, the PDCP variables of the re-established PDCP entity may not be reset to the initial values. In some embodiments, the stored PDCP variables of the PDCP entity in the old cell may be used as the initial values of PDCP variables of the re-established PDCP entity in the new cell. In this way, the PDCP variables are continuous and continuity of the MRB is achieved.
For the above options, the service continuity will be kept, e.g., the continuity of the MBS will be kept.
In some other cases, the new cell may be the same cell as the old cell, e.g. the UE may perform a cell selection or reselection procedure but the target cell is the currently serving cell and the above options may also be applied.
The present disclosure proposes some examples of the 3GPP documents, wherein the underlined expressions are proposed by the present disclosure.
When releasing a PDCP entity, the 3GPP documents may be as follows:
When establishing a PDCP entity, the 3GPP documents may be as follows:
When establishing a PDCP entity, the 3GPP documents may be also as follows:
In some embodiments, the UE may move out of the area in which continuity of the MRB is supported, and the UE may take the following options:
- releasing the PDCP entity of the MRB and acquiring an MCCH from the new cell. The UE may perform a PDCP establishment procedure according to the MRB configuration received in the MCCH. In some embodiment, releasing the PDCP entity of the MRB means the release of the MRB. A PDCP establishment procedure is performed during the establishment of a new MRB.
- releasing the PDCP entity of the MRB and triggering an RRC resume procedure for the new PDCP configuration by returning to an RRC connected state. When the UE returns to the RRC connected state, the new PDCP configuration is provided by RRC dedicated singalling.
The present disclosure further proposes some solutions for supporting continuity of an MRB as follows:
Solution 1
Fig. 5 illustrates a flow chart of supporting continuity of an MRB according to some embodiments of the present disclosure.
Fig. 5 includes a UE, BS 1 and BS 2. The UE may be UE 101 as shown in Fig. 1; BS 1 may be BS 102-A as shown in Fig. 1, and may manage cell 1; and BS 2 may be BS 102-B as shown in Fig. 1, and may manage cell 2.
In operation 501, BS 1 may transmit an RRC dedicated message, e.g., an RRCRelease message, to the UE. The message may indicate the UE to transition into the RRC non-connected state, e.g., an RRC inactive state or an RRC idle state. Furthermore, the message may include the information associated with PDCP of an MRB. In some embodiments, the information associated with PDCP of an MRB is provided by another RRC message, e.g. an RRCReconfiguraiton message. In some embodiments, the information associated with PDCP of the MRB may include area information in which continuity of the MRB is supported.
For example, referring to Fig. 1, the area information may indicate (or include) an area including the areas of cell 1, cell 2, and cell 3. In some cases, the area information may include area IDs, which may be preconfigured. In some other cases, the area information may be the names of certain areas. The area ID may be indicated in the RRC dedicated message in the old cell, and in the MCCH of the new cell. If the area IDs are the same between the old cell and the new cell, the UE shall treat the old cell and the new cell as in the same area in which continuity of the MRB is supported.
Alternatively, the area information may indicate (or include) a list of cells. For example, referring to Fig. 1, the area information may indicate a list of cells including cell 1, cell 2, and cell 3.
In operation 502, the UE may receive an MBS service in the RRC non-connected state.
In operation 503, the UE may perform cell reselection to a neighbor cell due to mobility. The UE may prioritize selecting the cell in the area or in the cell list in which continuity of the MRB is supported. In other words, the UE may prioritize selecting cell 1, cell 2 or cell 3 in the case the area information indicates cell 1, cell 2 or cell 3. The UE may reselect a cell in the area in which continuity of the MRB is supported, e.g., cell 2, and the UE may release the old RLC bearer used in cell 1.
In operation 504, the UE may receive an MCCH from BS 2, which may provide service to UEs in cell 2. The MCCH may indicate the RLC bearer and lower layer configuration for the MRB. The MCCH may also provide an indication, such as a PDCP reestablishment indication, and the UE may perform PDCP reestablishment as options 1-3 as described above.
In operation 505, for example, the UE may keep the PDCP entity used in cell 1 (e.g., option 1 as described above) and establish a new RLC entity according to RLC bearer and lower layer configuration for the MRB.
Alternatively, the UE may apply the options 2 or 3 as described above. For example, the MCCH may provide other indications to indicate the UE to release the old PDCP entity and establish a new PDCP entity (e.g., option 2 as described above) , or indicate the UE to re-establish the PDCP entity with kept PDCP variables (e.g., option 3 as described above) .
In some embodiments, the information associated with PDCP of an MRB, which is transmitted to the UE in cell 1 in operation 501, may further include one or more associated MRB IDs. For example, the information associated with PDCP of an MRB may include an associated MRB ID in each cell of the MRB.
The MRB IDs may be different among different cells. For example, the MRB ID of an MRB in cell 1 in Fig. 1 is MRB #1, the MRB ID of the same MRB in cell 2 in Fig. 1 is MRB #2, and the MRB ID of the same MRB in cell 3 in Fig. 1 is MRB #3. Accordingly, the information associated with PDCP of an MRB may include MRB #1 in cell 1, MRB #2 in cell 2, and MRB #3 in cell 3, or the like.
After the UE reselects to another cell within the area, e.g., cell 2, the UE may identify the MRB with the associated MRB ID (e.g., MRB #2 in cell 2) and associate the MRB in the second cell with the PDCP entity of the MRB #1 in the first cell, that is, associate MRB #2 with the PDCP entity. In this way, continuity of the MRB is achieved.
Returning to Fig. 5, in operation 504, the UE may acquire the MCCH to obtain the RLC configuration of the MRB in the neighbor cell (e.g., cell 2) . The UE may identify the MRB with the associated MRB ID, e.g., MRB #2 in cell 2, associate the MRB #2 to the PDCP entity, and reuse the values of PDCP variables in the old cell (e.g., cell 1) .
In some other embodiments, the information associated with PDCP of an MRB, which is transmitted to the UE in cell 1 in operation 501, may further include an associated RLC bearer ID.
Still referring to Fig. 5, in operation 504, the received MCCH may indicate an RLC bearer configuration of the MRB, and the UE may establish a second RLC bearer of the MRB in the second cell based on the RLC bearer configuration of the MRB. The UE may associate the same PDCP entity in the first cell (e.g., cell 1) with the second RLC bearer in the second cell (e.g., cell 2) .
In the case that the wireless communication system includes a CU and a DU, such as a gNB-CU and gNB-DU, the CU may decide the area in which continuity of an MBS is supported, and send the area information to the DU, so that the gNB-DU can be aware of the area information and set the parameters of the PDCP configurations, e.g., PDCP-Config, in the MCCH.
Similarly, a BS may also send the area information and corresponding PDCP configuration to a neighbor BS by an interface between the BSs, e.g., an Xn interface, in order to achieve the continuity of the MBS coordination between the BSs.
Solution 2
Still referring to Fig. 5, in operation 501, BS 1 may transmit an RRC dedicated message, e.g., an RRCRelease message, to the UE. Furthermore, the information associated with continuity of an MBS may include one or more indexes of PDCP configurations, for example, a list of indexes of PDCP configurations. Each index may correspond to one or more PDCP configurations. For example, the list may be as follows:
index 1:
PDCP configuration 1;
PDCP configuration 2;
index 2:
PDCP configuration 3;
PDCP configuration 4;
PDCP configuration 5;
index 3:
PDCP configuration 6;
etc.
For example, the index included in the message from BS 1 may be index 1. The BS may further indicate the index of PDCP configuration of the MRB currently used by the UE, e.g., the PDCP configuration of the MRB currently used by the UE in cell 1, e.g., index 1.
In some embodiments, the information associated with continuity of the MBS may further include the PDCP configuration corresponding to each index. In some other embodiments, the PDCP configuration corresponding to each index may be predefined, preconfigured, and specified in the specification, and the information associated with continuity of the MBS may not include the PDCP configurations. In this way, the network may only configure the reference index to the UE, and the UE may know the corresponding PDCP configuration according to the reference index as pre-defined by the specification.
In some embodiments, the message may also indicate the area information associated with continuity of the MBS as described in solution 1.
The UE may perform operations 502 and 503 in a similar fashion as in solution 1.
In operation 504, the UE may acquire the MCCH and obtain the PTM configuration of the MRB. In the PTM configuration of the MRB, the index of the PDCP configuration of cell 2 may be provided.
In the case that the index of the PDCP configuration of cell 2 is the same as the index of the PDCP configuration currently used by the UE, the UE may use the one or more PDCP variables for continuity of the MRB. For example, the index included in the message from BS 2 (which controls cell 2) may also be index 1, thus the UE may use the one or more PDCP variables for continuity of the MRB.
In the case that the index provided by the MCCH is the different from the index of the PDCP configuration currently used by the UE, for example, the index included in the message from BS 2 (which controls cell 2) may also be index 2, the UE may release the old PDCP entity and apply the PDCP configuration indicated by the index, e.g., PDCP configuration 2 for establishing a new MRB.
In some embodiments, after reselecting to a second cell that is in the area in which continuity of the MRB is supported, or the reference index of the PDCP configuration is the same as the using one, the PDCP variables, such as RX_NEXT, RX_DELIV, or the like, may not be continuous. For example, the stored PDCP variable RX_NEXT may be 3, while the first received packet, may be 10. It is supposed that a threshold may be configured, such as 5, and the difference between the value of the first received packet and the stored PDCP variable is 7, which is larger than the threshold. The UE may determine that the continuity of the MRB is not achieved. In this case, the UE may trigger a PDCP status report and an RRC resume procedure in the second cell. The report may indicate the gap of the PDCP variable.
In some other cases, the trigger condition may be a the PDCP SN of the first receiving packet in the new cell is smaller than a configured threshold of the previous stored PDCP variable, for example, the RX_DELIV. Other trigger conditions may also be defined to indicate the network regarding the continuity of the MRB is not achieved.
Solution 3
Fig. 6 illustrates a flow chart of supporting continuity of an MRB according to some embodiments of the present disclosure.
Fig. 6 includes a UE and BS 1. The UE may be UE 101 as shown in Fig. 1; and BS 1 may be BS 102-A as shown in Fig. 1, and may manage cell 1.
Operations 601 and 602 are similar to operations 501 and 502 as described in Fig. 5 respectively, and details are omitted here.
In operation 603, the UE acquires MCCH in cells 1 for update of PTM configuration. In the updated configuration of the MRB, the index of PDCP configuration may be provided.
In operation 604, in the case that the index of the updated PDCP configuration is the same as the index of the PDCP configuration currently used by the UE, the UE may use the one or more PDCP variables for continuity of the MRB. For example, the index included in the MCCH may also be index 1, thus the UE may use the one or more PDCP variables for continuity of the MRB.
In operation 605, the UE may receive the MCCH for update of the PTM configuration. The MCCH may indicate the RLC bearer and lower layer configuration for the MRB. The MCCH may also provide an indication, such as a PDCP reestablishment indication, and the UE may perform PDCP reestablishment as options 1-3 as described above.
Fig. 7 illustrates a simplified block diagram of an apparatus according to some embodiments of the present disclosure.
As shown in Fig. 7, an example of the apparatus 700 may include at least one processor 704 and at least one transceiver 702 coupled to the processor 704. The apparatus 700 may be a UE, a BS, a CU, a DU, or any other device with similar functions.
Although in this figure, elements such as the at least one transceiver 702 and processor 704 are described in the singular, the plural is contemplated unless a limitation to the singular is explicitly stated. In some embodiments of the present disclosure, the transceiver 702 may be divided into two devices, such as a receiving circuitry and a transmitting circuitry. In some embodiments of the present disclosure, the apparatus 700 may further include an input device, a memory, and/or other components.
In some embodiments of the present disclosure, the apparatus 700 may be a UE. The transceiver 702 and the processor 704 may interact with each other so as to perform the operations of the UE described in any of Figs. 1-6. In some embodiments of the present disclosure, the apparatus 700 may be a node. The transceiver 702 and the processor 704 may interact with each other so as to perform the operations of the node described in any of Figs. 1-6.
In some embodiments of the present disclosure, the apparatus 700 may further include at least one non-transitory computer-readable medium.
For example, in some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause the processor 704 to implement the method with respect to the UE as described above. For example, the computer-executable instructions, when executed, cause the processor 704 interacting with transceiver 702 to perform the operations of the UE described in any of Figs. 1-6.
In some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause the processor 704 to implement the method with respect to the node as described above. For example, the computer-executable instructions, when executed, cause the processor 704 interacting with transceiver 702 to perform the operations of the node described in any of Figs. 1-6.
The method of the present disclosure can be implemented on a programmed processor. However, controllers, flowcharts, and modules may also be implemented on a general purpose or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit elements, an integrated circuit, a hardware electronic or logic circuit such as a discrete element circuit, a programmable logic device, or the like. In general, any device that has a finite state machine capable of implementing the flowcharts shown in the figures may be used to implement the processing functions of the present disclosure.
While the present disclosure has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in other embodiments. Also, all of the elements shown in each Fig. are not necessary for operation of the disclosed embodiments. For example, one skilled in the art of the disclosed embodiments would be capable of making and using the teachings of the present disclosure by simply employing the elements of the independent claims. Accordingly, the embodiments of the present disclosure as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the present disclosure.
In this disclosure, relational terms such as "first, " "second, " and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "includes, " "including, " or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "a, " "an, " or the like does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that includes the element. Also, the term "another" is defined as at least a second or more. The terms "including, " "having, " and the like, as used herein, are defined as "including. "

Claims

A user equipment (UE) , comprising:

a transceiver; and

a processor coupled with the transceiver and configured to:

receive, via the transceiver, information associated with packet data convergence protocol (PDCP) of a multicast radio bearer (MRB) via a radio resource control (RRC) dedicated signaling, wherein the PDCP comprises one or more PDCP variables;

transition to an RRC non-connected state; and

determine, based on the information associated with the PDCP of the MRB, whether to use the one or more PDCP variables for continuity of the MRB while the UE is in the RRC non-connected state.
The UE of Claim 1, wherein, the information associated with PDCP of the MRB includes an area or a list of cells in which continuity of the MRB is supported.
The UE of Claim 2, wherein the processor is further configured to:

perform cell reselection from a first cell to a second cell; and

use the one or more PDCP variables for continuity of the MRB in the case that the first cell and the second cell are within the area or in the list of cells.
The UE of Claim 3, wherein, the processor is configured to:

release a first radio link control (RLC) bearer of the MRB in the first cell when leaving the first cell;

acquire a RLC bearer configuration of the MRB via a multicast/broadcast services control channel (MCCH) in the second cell when entering the second cell; and

establish a second RLC bearer of the MRB in the second cell according to the RLC bearer configuration of the MRB.
The UE of Claim 3, wherein, the information associated with the PDCP of the MRB indicates a first identity (ID) of the MRB in the first cell and a second ID of the MRB in the second cell, and wherein the processor is further configured to:

associate the MRB in the second cell with a PDCP entity of the MRB in the first cell.
The UE of Claim 1, wherein, the information associated with the PDCP of the MRB indicates one or more indexes of PDCP configurations.
The UE of Claim 7, wherein the one or more indexes comprise a first index of a PDCP configuration, and the processor is further configured to:

perform cell reselection from a first cell to a second cell;

receive a second index of a PDCP configuration in the second cell from a multicast/broadcast services control channel (MCCH) ; and

use the one or more PDCP variables for continuity of the MRB in the case that the first index and second index are identical.
The UE of Claim 3 or 7, wherein in order to use the one or more PDCP variables for continuity of the MRB, the processor is further configured to:

store the one or more PDCP variables of a PDCP entity of the MRB used in the first cell;

release the PDCP entity of the MRB and establish a new PDCP entity of a new MRB in the second cell; and

set one or more PDCP variables of the new PDCP entity of the new MRB with the one or more PDCP variables of the PDCP entity as stored.
The UE of Claim 3 or 7, wherein in order to use the one or more PDCP variables for continuity of the MRB, the processor is further configured to:

keep a same PDCP entity of the MRB in the second cell; and

continue to use latest PDCP variables of the PDCP entity of the MRB in the second cell.
The UE of Claim 3 or 7, wherein in order to use the one or more PDCP variables for continuity of the MRB, the processor is further configured to:

reestablish the PDCP entity of the MRB in the second cell; and

continue to use the latest PDCP variables of the PDCP entity of the MRB in the second cell.
The UE of Claim 3 or 7, wherein the processor is further configured to:

trigger a PDCP status report and an RRC resume procedure in the second cell in the case that a PDCP variable of a first received packet in the second cell is larger or smaller than a corresponding stored PDCP variable by a threshold.
A base station (BS) , comprising:

a transceiver; and

a processor coupled with the transceiver and configured to:

determine information associated with packet data convergence protocol (PDCP) of a multicast radio bearer (MRB) , wherein the PDCP comprises one or more PDCP variables; and

transmit, via the transceiver, the information associated with PDCP of the MRB to a user equipment (UE) via a radio resource control (RRC) dedicated signaling.
The BS of Claim 12, wherein the information associated with the PDCP of the MRB includes an area or a list of cells in which continuity of the MRB is supported.
The BS of Claim 12, wherein the information associated with the PDCP of the MRB indicates one or more indexes of PDCP configurations.
A method performed by a user equipment (UE) , comprising:

receiving information associated with packet data convergence protocol (PDCP) of a multicast radio bearer (MRB) via a radio resource control (RRC) dedicated signaling, wherein the PDCP comprises one or more PDCP variables;

transitioning to an RRC non-connected state; and

determining, based on the information associated with the PDCP of the MRB, whether to use the one or more PDCP variables for continuity of the MRB while the UE is in the RRC non-connected state.