WO2023245346A1

WO2023245346A1 - Methods and apparatus to set mrb configuration for ue to receive mbs multicast in rrc inactive state

Info

Publication number: WO2023245346A1
Application number: PCT/CN2022/099878
Authority: WO
Inventors: Xiaonan Zhang; Yuanyuan Zhang; Xuelong Wang
Original assignee: Mediatek Singapore Pte. Ltd.
Priority date: 2022-06-20
Filing date: 2022-06-20
Publication date: 2023-12-28
Also published as: CN117278945A

Abstract

This disclosure describes methods and apparatus to support multicast reception for UE in RRC INACTIVE state. A particular procedure is introduced to receive MRB configuration from the network, perform MRB establishment and update multicast MTCH information. When UE joins the multicast session when the session is not start yet, the network sends UE to RRC INACTIVE state by RRCRelease with suspendconfig. In one embodiment, the multicast MRB configuration is delivered in the suspendconfig, and UE stores the configuration in buffer. The UE will perform multicast MRB configuration procedure according to the stored configuration when UE receives the group paging notification for the multicast session.

Description

METHODS AND APPARATUS TO SET MRB CONFIGURATION FOR UE TO RECEIVE MBS MULTICAST IN RRC INACTIVE STATE

FIELD

The present disclosure relates generally to communication systems, and more particularly, the method to set MRB configuration for UE to receive MBS multicast in RRC inactive state.

BACKGROUND

Various cellular systems, including both 4G/LTE and 5G/NR systems, may provide a multicast functionality, which allows user equipments (UEs) in the system to receive multicast services transported by the cellular system. A variety of applications may rely on communication over multicast transmission, such as live stream, video distribution, vehicle-to-everything (V2X) communication, public safety (PS) communication, file download, and so on. In legacy system, the multicast service is received by UE which in RRC CONNECTED state. For high load/congestion scenario, it may be possible for UE to receive multicast service in RRC connected state. It can also improve the multicast service in terms of power saving, service coverage and spectrum efficiency. In NR multicast, UE may join the multicast session before the session start, and come back to RRC CONNECTED when UE received the group paging for multicast. For multicast reception via RRC INACTIVE state, some steps in session start may be simplified. and some procedure may be needed to update multicast MTCH information when certain conditions are met.

In this invention, apparatus and mechanisms are sought to support UE to set MRB configuration for MBS multicast reception in RRC INACTIVE state.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. When UE joins the multicast session when the session is not start yet, the network sends UE to RRC INACTIVE state by RRCRelease with suspendconfig. In one embodiment, the multicast MRB configuration is delivered in the suspendconfig, and UE stores the configuration in buffer. The UE will perform multicast MRB configuration procedure according to the stored configuration when UE receives the group paging notification for the multicast session.

When UE joins an ongoing multicast session, the network may send UE to RRC INACTIVE state due to the high traffic load, and the network sends UE to RRC INACTIVE state by RRCRelease with suspendconfig. In one embodiment, the multicast MRB configuration is delivered in the suspendconfig, and UE performs multicast MRB configuration procedure according to the indication from the network.

When UE receiving multicast service in RRC INACTIVE moves to another cell, or periodically, UE may need to update the multicast resource from the network. In one embodiment, the multicast update request is delivered via RRCResumeRequest, and the multicast configuration is updated by RRCRelease indicated by network. In one embodiment, the multicast resource is not changed, and UE can receive the multicast service on target cell without reconfiguration.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a schematic system diagram illustrating an exemplary wireless network in accordance with embodiments of the current invention.

Figure 2 illustrates an exemplary NR wireless system with centralization of the upper layers of the NR radio stacks in accordance with embodiments of the current invention.

Figure 3 illustrate an exemplary flowchart of procedures for UE to receive MRB configuration for multicast reception by RRCRelease message in accordance with embodiments of the current invention.

Figure 4 illustrate an exemplary flowchart of procedures for UE to set MRB configuration for multicast reception according to stored MRB configuration from buffer in accordance with embodiments of the current invention.

Figure 5 illustrate an exemplary flowchart of procedures for UE being set to RRC INACTIVE to receive multicast service in accordance with embodiments of the current invention.

Figure 6 illustrate an exemplary overall flow for UE to set MRB configuration for multicast reception by RRCRelease message and perform multicast MRB configuration procedure in accordance with embodiments of the current invention.

Figure 7 illustrate an exemplary overall flow for UE being indicated to receive multicast service in RRC INACTIVE in accordance with embodiments of the current invention.

Figure 8 illustrate an exemplary overall flow for UE to trigger multicast update procedure by RRCResumeRequest and receives multicast service from target gNB in RRC INACTIVE state in accordance with embodiments of the current invention.

Figure 9 illustrate an exemplary overall flow for the case when UE triggers multicast update procedure and the gNB decides not to relocate the UE context in accordance with embodiments of the current invention.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements” ) . These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

Aspects of the present disclosure provide methods, apparatus, processing systems, and computer readable mediums for NR (new radio access technology, or 5G technology) or other radio access technology. NR may support various wireless communication services. These services may have different quality of service (QoS) requirements e.g. latency and reliability requirements.

Figure 1 illustrates a schematic system diagram illustrating an exemplary wireless network in accordance with embodiments of the current invention. Wireless system includes one or more fixed base infrastructure units forming a network distributed over a geographical region. The base unit may also be referred to as an access point, an access terminal, a base station, a Node-B, an eNode-B, a gNB, or by other terminology used in the art. As an example, base stations serve a number of mobile stations within a serving area, for example, a cell, or within a cell sector. In some systems, one or more base stations are coupled to a controller forming an access network that is coupled to one or more core networks. gNB 1and gNB 2 are base stations in NR, the serving area of which may or may not overlap with each other. As an example, UE1 or mobile station is only in the service area of gNB 1 and connected with gNB1. UE1 is connected with gNB1 only, gNB1 is connected with gNB2 via Xn interface. UE2 is in the overlapping service area of gNB1 and gNB2. In one embodiment, both gNB1 and gNB2 provide the same MBS services, service continuity during handover is guaranteed when UE 2 moves from gNB1 to gNB2 and vice versa.

Figure 1 further illustrates simplified block diagrams for UE2 and gNB2, respectively. UE has an antenna, which transmits and receives radio signals. A RF transceiver, coupled with the antenna, receives RF signals from antenna, converts them to baseband signal, and sends them to processor. In one embodiment, the RF transceiver may comprise two RF modules (not shown) . A first RF module is used for transmitting and receiving on one frequency band, and the other RF module is used for different frequency bands transmitting and receiving which is different from the first transmitting and receiving. RF transceiver also converts received baseband signals from processor, converts them to RF signals, and sends out to antenna. Processor processes the received baseband signals and invokes different functional modules to perform features in UE. Memory stores program instructions and data to control the operations of mobile station. UE also includes multiple function modules that carry out different tasks in accordance with embodiments of the current invention.

A RRC State controller, which controls UE RRC state according to network’s command and UE conditions. RRC supports the following states, RRC_IDLE, RRC_CONNECTED and RRC_INACTIVE. In one embodiment, UE can receive the multicast services in RRC INACTIVE state. The UE applies the MRB establishment procedure to start receiving a session of a service it has joined in. The UE applies the MRB release procedure to stop receiving a session.

A MRB controller, which controls to establish/add, reconfigure/modify and release/remove a MRB based on different sets of conditions for MRB establishment, reconfiguration and release. A protocol stack controller, which manage to add, modify or remove the protocol stack for the MRB. The protocol Stack includes RLC, MAC and PHY layers. In one embodiment, the SDAP layer is optionally configured.

In one embodiment, the PDCP layer supports the functions of transfer of data, maintenance of PDCP SN, header compression and decompression using the ROHC protocol, ciphering and deciphering, integrity protection and integrity verification, timer based SDU discard, routing for split bearer, duplication, re-ordering and in-order delivery; out of order delivery and duplication discarding. In one embodiment, the receiving PDCP entity sends PDCP status report upon t-Reordering expiry. In one embodiment, the PDCP status reports triggers PDCP retransmission at the peer transmitting PDCP entity at the network side.

In one embodiment, the RLC layer supports the functions of error correction through ARQ, segmentation and reassembly, re-segmentation, duplication detection, re-establishment, etc. In one embodiment, a new procedure for RLC reconfiguration is performed, which can reconfigure the RLC entity to associated to one or two logical channels.

In one embodiment, the MAC layer supports the following functions: mapping between logical channels and transport channels, multiplexing/demultiplexing, HARQ, radio resource selection, etc.

Similarly, gNB2 has an antenna, which transmits and receives radio signals. A RF transceiver, coupled with the antenna, receives RF signals from antenna, converts them to baseband signals, and sends them to processor. RF transceiver also converts received baseband signals from processor, converts them to RF signals, and sends out to antenna. Processor processes the received baseband signals and invokes different functional modules to perform features in gNB2. Memory stores program instructions and data to control the operations of gNB2. gNB2 also includes multiple function modules that carry out different tasks in accordance with embodiments of the current invention.

A RRC State controller, which performs access control for the UE.

A MRB controller, which controls to establish/add, reconfigure/modify and release/remove a MRB based on different sets of conditions for MRB establishment, reconfiguration and release. A protocol stack controller, which manage to add, modify or remove the protocol stack for the MRB. The protocol Stack includes SDAP, PDCP, RLC, MAC and PHY layers.

Figure 2 illustrates an exemplary NR wireless system with centralization of the upper layers of the NR radio stacks in accordance with embodiments of the current invention. Different protocol split options between Central Unit and lower layers of gNB nodes may be possible. The functional split between the Central Unit and lower layers of gNB nodes may depend on the transport layer. Low performance transport between the Central Unit and lower layers of gNB nodes can enable the higher protocol layers of the NR radio stacks to be supported in the Central Unit, since the higher protocol layers have lower performance requirements on the transport layer in terms of bandwidth, delay, synchronization and jitter. In one embodiment, SDAP and PDCP layer are located in the central unit, while RLC, MAC and PHY layers are located in the distributed unit.

Figure 3 illustrate an exemplary flowchart of procedures for UE to receive MRB configuration for multicast reception by RRC release message in accordance with embodiments of the current invention. When UE joins the multicast when the session is not started yet, or the session is already started but temporarily no DL data, in one embodiment, the network sends UE to RRC INACTIVE state by RRCRelease with suspendconfig. In one embodiment, the multicast MRB configuration is delivered in the suspendconfig. In one embodiment, the network sends UE to RRC idle by RRCRelease, and the multicast MRB configuration is delivered in the RRCRelease message. In one embodiment, the UE receives the multicast configuration, and UE stores the configuration in buffer.

Figure 4 illustrate an exemplary flowchart of procedures for UE to set MRB configuration for multicast reception according to stored MRB configuration from buffer in accordance with embodiments of the current invention. When UE receives the group paging notification for multicast service from the network. In one embodiment, UE is in RRC INACTIVE state, and UE performs multicast MRB configuration procedure according to the stored multicast configuration. In one embodiment, UE is in RRC IDLE state, and UE requests to switch back to RRC CONNECTED, then performs multicast MRB configuration procedure according to the stored multicast configuration. After UE performs the multicast MRB configuration, UE starts to receive the multicast service. In one embodiment, UE stays in RRC CONNECTED to receive multicast service. In one embodiment, UE stays in RRC INACTIVE state to receive multicast service.

Figure 5 illustrate an exemplary flowchart of procedures for UE being set to RRC INACTIVE to receive multicast service in accordance with embodiments of the current invention. If UE joins the multicast when the session is already started, and network wants the UE to receive data in RRC INACTIVE state, in one embodiment, the network sends UE to RRC INACTIVE state by RRCRelease with suspendconfig. In one embodiment, the multicast MRB configuration is delivered in the suspendconfig, and UE performs multicast MRB configuration procedure according to the indication from the network. After UE performs the multicast MRB configuration, UE starts to receive the multicast service in RRC INACTIVE state.

Figure 6 illustrate an exemplary overall flow for UE to set MRB configuration for multicast reception by RRC release message and perform multicast MRB configuration procedure in accordance with embodiments of the current invention. If UE joined in a multicast session in RRC CONNECTED state and there is temporarily no DL data in the multicast session, in one embodiment, the network sends UE to RRC INACTIVE state by RRCRelease with suspend indication. In one embodiment, the multicast MRB configuration is delivered in the suspend indication, which indicates the MTCH information for the upcoming multicast session. When UE receives the group paging notification from the network. In one embodiment, UE establishes RRC connection and receives multicast service in RRC CONNECTED. In one embodiment, UE performs multicast MRB configuration procedure according to the stored multicast configuration and starts to receive the multicast service in RRC INACTIVE.

Figure 7 illustrate an exemplary overall flow for UE being indicated to receive multicast service in RRC INACTIVE in accordance with embodiments of the current invention. If UE joined in a multicast session in RRC CONNECTED state and the multicast session is ongoing, in one embodiment, the network sends UE to RRC INACTIVE state by RRCRelease with suspend indication. In one embodiment, the multicast MRB configuration is delivered in the suspend indication, which indicates the MTCH information for the upcoming multicast session. In one embodiment, the multicast MRB configuration is delivered by RRCReconfiguration message before RRCRelease message. After performing multicast MRB configuration procedure, UE receives the multicast service in RRC INACTIVE.

Figure 8 illustrate an exemplary overall flow for UE to trigger multicast update procedure by RRCResumeRequest and receives multicast service from target gNB in RRC INACTIVE state in accordance with embodiments of the current invention. Before the multicast update procedure, UE receives the DL user data in RRC INACTIVE state from the source gNB.

1. The UE sends RRCResumeRequest to the target gNB, providing the I-RNTI, allocated by the last serving gNB and appropriate cause value.

In one embodiment, the cause value is specific to update multicast reception in RRC INACTIVE.

In one embodiment, UE sends RRCResumeRequest with multicast update for ResumeCause when UE moves to a different cell. In one embodiment, UE sends RRCResumeRequest with multicast update for ResumeCause when UE is in the same cell, but the MTCH information for multicast service which UE interested in has been changed. In one embodiment, UE sends RRCResumeRequest with multicast update for ResumeCause periodically.

2. The gNB, if able to resolve the gNB identity contained in the I-RNTI, requests the last serving gNB to provide UE Context, providing the cause value received in step 1.

3. The last serving gNB may provide the UE context (as assumed in the following)

4. If loss of DL user data buffered in the last serving gNB shall be prevented, the gNB provides forwarding addresses.

5. The target gNB sends PATH SWITCH REQUEST to AMF.

6. The AMF indicates PATH SWITCH RESPONSE to target gNB.

7. The gNB keeps the UE in RRC_INACTIVE state by sending RRCRelease with suspend indication. In one embodiment, the multicast MRB configuration is delivered in the suspend indication, which indicates the MTCH information for the multicast session which UE is interested in. UE performs multicast MRB configuration procedure according to the indication.

8. UE receives multicast service from target gNB in RRC INACTIVE state.

9. The gNB triggers the release of the UE resources at the last serving gNB.

Figure 9 illustrate an exemplary overall flow for the case when UE triggers multicast update procedure and the gNB decides not to relocate the UE context in accordance with embodiments of the current invention. Before UE triggers the multicast update procedure, UE receives the DL user data in RRC INACTIVE state from the gNB.

1. The UE sends RRCResumeRequest to the gNB, providing the I-RNTI, allocated by the last serving gNB and appropriate cause value.

2. The gNB keeps the UE in RRC_INACTIVE state by sending RRCRelease with suspend indication.

In one embodiment, the multicast MRB configuration is delivered in the suspend indication, which indicates the MTCH information for the multicast session which UE is interested in. UE performs multicast MRB configuration procedure according to the indication.

3. UE receives multicast service in RRC INACTIVE state.

It is understood that the specific order or hierarchy of blocks in the processes /flowcharts disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes /flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module, ” “mechanism, ” “element, ” “device, ” and the like may not be a substitute for the word “means. ” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for. ”

While aspects of the present disclosure have been described in conjunction with the specific embodiments thereof that are proposed as examples, alternatives, modifications, and variations to the examples may be made. Accordingly, embodiments as set forth herein are intended to be illustrative and not limiting. There are changes that may be made without departing from the scope of the claims set forth below.

Claims

A method to control a UE to receive multicast configuration and perform MRB establishment for multicast reception in RRC inactive, comprising the steps of:

Receives MRB configuration from the network;

Performs MRB configurations for multicast reception in RRC INACTIVE state; and

Requests to update multicast MTCH information when certain conditions are met.
The method of claim 1, further comprising UE receives MRB configuration from network for multicast reception by RRC release message.
The method of claim 2, wherein the MRB configuration is delivered by suspendconfig.
The method of claim 2, wherein there is temporarily no DL data for multicast service and UE stores the MRB configuration in buffer.
The method of claim 1, further comprising UE performs MRB configuration procedure for multicast reception by the information in RRCRelease message.
The method of claim 5, wherein the procedure is performed after UE receives group notification for the multicast service from the network.
The method of claim 6, further comprising UE performs MRB configuration by the information stored in UE buffer.
The method of claim 6, wherein the UE performs the procedure in RRC CONNECTED state.
The method of claim 6, wherein the UE performs the procedure in RRC INACTIVE state.
The method of claim 5, wherein the multicast session is ongoing and UE performs MRB configuration in RRC INACTIVE state.
The method of claim 1, further comprising UE updates multicast MTCH information by RRCResumeRequest.
The method of claim 11, wherein the UE request multicast updates by RRCResumeRequest with multicast update for ResumeCause.
The method of claim 11, wherein the UE receiving multicast in RRC inactive states moves to another cell in the same RNA area.
The method of claim 11, wherein the MTCH information for multicast service which UE interested in has been changed.
The method of claim 11, wherein the UE updates the multicast MTCH information periodically.
A method for the network to support multicast reception for UE in RRC INACTIVE state, comprising the steps of:

Indicates MRB configuration for specific UE (s) by RRCRelease message;

Update the multicast MTCH information according to the multicast update request from UE; and

Switch the path for UE to target cell to receive multicast service in RRC INACTIVE state.
The method of claim 16, wherein the MRB configuration is delivered by suspendconfig in RRCRelease.
The method of claim 16, wherein the multicast MTCH information is delivered by suspendconfig in RRCRelease.