WO2023130452A1

WO2023130452A1 - Methods and apparatus for sdap based xr packets inspection and classification at radio access layer

Info

Publication number: WO2023130452A1
Application number: PCT/CN2022/071036
Authority: WO
Inventors: Xiaonan Zhang; Xuelong Wang
Original assignee: Mediatek Singapore Pte. Ltd.
Priority date: 2022-01-10
Filing date: 2022-01-10
Publication date: 2023-07-13

Abstract

This disclosure describes methods and apparatus for SDAP based XR packets awareness mechanism. A particular procedure is introduced to perform finer granularity classification for XR traffic, implemented by packets inspection and classification for packets with different QoS requirements at SDAP layer, and following packet handling procedure is introduced to PDCP/RLC/MAC layer.

Description

METHODS AND APPARATUS FOR SDAP BASED XR PACKETS INSPECTION AND CLASSIFICATION AT RADIO ACCESS LAYER

FIELD

The present disclosure relates generally to communication systems, and more particularly, the method to inspect and classify XR Packets at radio access layer.

BACKGROUND

Typical XR (eXtended Reality) traffic includes various types of media data which have different characteristics (in terms of Periodicity, Jitter, Packet size and PDB) and QoS requirements may be supported in future 5G/NR systems, which allow users equipments (UEs) in the system to receive XR services transported by the cellular system. A variety of applications may rely on communication over XR transmission, such as distance learning, cloud gaming, telemedicine, industrial design, and so on. Overall, XR traffic may represent the requirement of the combination with low latency, high data rate and high reliability. For XR traffic, some of the packets are assembled based on important frames of the XR stream, which requires special handling to avoid data loss. In legacy system, radio access layer does not distinguish the packets for the traffic coming from IP layer, and current L1/L2 retransmission may not be suitable for XR traffic due to extra latency. Therefore, a packet inspection mechanism to perform finer granularity classification for XR traffic and corresponding packet handling procedure are needed for current radio access systems.

In this invention, apparatus and mechanisms are sought to perform finger granularity packets inspection and classification at radio access layer.

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. an XR traffic awareness mechanism for UE is introduced at radio access layer in both downlink RX side and uplink TX side. In one embodiment, the XR awareness mechanism is based on SDAP packet inspection. On the transmitting side, SDAP inspects the packet header from upper layer, and maps QoS flow to different DRBs according to critical/non-critical packets. In one embodiment, RRC indicates different DRBs for different discardtimer, and PDCP PDUs with critical XR packets will be discarded after longer waiting time. Different DRBs are map to logical channels with different LCIDs, which are configured with different priorities, PBRs and BSDs. In one embodiment, RLC PDUs from different logical channels will be prioritized and multiplexed to MAC PDUs. In one embodiment, the MAC PDU with critical packets will be distributed to a different HARQ processes for blind retransmission.

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 illustrates an exemplary frame fragmentation and packet handling procedure at Internet layers and radio access layer for XR traffic in accordance with embodiments of the current invention.

Figure 4 illustrates an exemplary protocol stack for a SDAP based XR packet inspection and classification mechanism in accordance with embodiments of the current invention.

Figure 5 illustrate an exemplary flowchart for SDAP to receive a QoS flow of XR traffic and the procedure of inspection and packet classification to different DRBs in accordance with embodiments of the current invention.

Figure 6 illustrate an exemplary flowchart for PDCP entities to receive SDAP PDUs with XR traffic and set different discardtimer to different DRBs by RRC indication in accordance with embodiments of the current invention.

Figure 7 illustrate an exemplary flowchart for RLC entities to receive PDCP PDUs with XR traffic from different DRBs and map to logical channels with different LCIDs by RRC indication in accordance with embodiments of the current invention.

Figure 8 illustrate an exemplary flowchart for MAC entity to prioritize RLC PDUs with XR traffic from different logical channels and multiplex to MAC PDUs by RRC indication. The MAC PDU with higher priority SDUs will be perform blind HARQ retransmission in accordance with embodiments of the current invention.

Figure 9 illustrates an exemplary process of an XR traffic packet handling at Internet layers and radio access layer with SDAP based packet inspection and classification mechanism 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 gNB 1 and 2 via Xn interface. UE2 is in the overlapping service area of gNB1 and gNB2. In one embodiment, both gNB1 and gNB2 provide the same XR 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 broadcast services in RRC_IDLE/INACTIVE state. The UE applies the DRB establishment procedure to start receiving a session of a service it has an interest in. The UE applies the DRB release procedure to stop receiving a session.

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

In one embodiment, the SDAP layer supports the functions of transfer of data, mapping between a QoS flow and a DRB, marking QoS flow ID, reflective QoS flow to DRB mapping for the UL SDAP data PDUs, etc.

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 DRB controller, which controls to establish/add, reconfigure/modify and release/remove a DRB based on different sets of conditions for DRB establishment, reconfiguration and release. A protocol stack controller, which manage to add, modify or remove the protocol stack for the DRB. The protocol Stack includes RLC, MAC and PHY layers. In one embodiment, the transmitting PDCP entity buffers the PDCP PDUs and performs retransmission based on the received PDCP status reports from the UEs.

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 illustrates an exemplary frame fragmentation and packet handling procedure at Internet layers and radio access layer for XR traffic in accordance with embodiments of the current invention. The legacy frame fragmentation of XR like traffic is performed at real time transport layer (e.g. RTP) with encoder (e.g. Network Adaptation Layer of H. 264) . During stream coding in encoder and packet assemble in the media streaming transport layer (e.g., RTP layer) , various packet information may be included within the protocol header. The said information can be one or a plural of the following: (1) the packet belongs to which media streaming slice; (2) the packet belongs to which application data unit; (3) the packet belongs to which encoding layer (e.g. base layer or enhanced layer for better quality viewing) ; (4) the packet belongs to which media streaming frame (5) the packet belongs to which type of media streaming frame (e.g. I-frame or P-frame) ; (6) the packet belongs to critical data or non-critical data; (7) the packet delay budget for the packet; (8) priority of the packet; (9) the packet is new transmission or retransmission at media streaming transport layer or application; (10) the packet is a redundant packet or a non-redundant transmission; (11) the packet is a control packet or a data streaming packet from media streaming transport layer; (12) the reliability requirement of the packet.

UDP/IP header do not contain frame information and payload types. In one embodiment, RTP set the proper packet size for XR transmission and IP fragmentation is not enabled. In the transmitting side of radio access layer, the XR traffic packed by internet protocol will be delivered to SDAP layer by QoS flow. After packet handling procedure of PDCP and RLC, the RLC PDU is delivered to MAC layer. MAC entity multiplexes multiple RLC PDUs to a TB (i.e. MAC PDU) and then deliver the TB to physical layer. At the receiving side, each layer decodes and delivers the packet to upper layer according to the header information.

Figure 4 illustrates an exemplary protocol stack for a SDAP based XR packet inspection and classification mechanism in accordance with embodiments of the current invention. For radio access layer, the QoS flow of XR traffic will be delivered to SDAP layer. In one embodiment, SDAP inspects the transport packet header (e.g. IP/UDP/RTP) and know the packet characteristics. Then SDAP maps the QoS flow to multiple DRBs to classify critical packets and non-critical packets. DRBs with different XR packets are submitted to different PDCP entities. In one embodiment, PDCP configures different DRBs with different discardtimers by RRC indication, and PDCP PDUs with critical XR packets will be discarded after longer waiting time. In one embodiment, PDCP PDUs from different DRBs are mapped to different RLC entities with different logical channels, which are configured with different priorities. RLC PDUs from different logical channels will then be prioritized and multiplexed to MAC PDUs. In one embodiment, the MAC PDU with critical packets will be distributed to a different HARQ entities for blind retransmission to enhance its reliability.

Figure 5 illustrate an exemplary flowchart for SDAP to receive a QoS flow of XR traffic and the procedure of inspection and packet classification to different DRBs in accordance with embodiments of the current invention. In one embodiment, SDAP is reconfigured for XR traffic by RRC signaling. After receiving QoS flow of XR traffic from the upper layer, SDAP inspects the header of IP packet to check the DSCP value. IP packets with DSCP value consistent with XR characteristics are regarded as XR traffic packets. In one embodiment, SDAP then inspects UDP and RTP header of XR packets to check RTP payload type. For critical/non-critical video frames, SDAP distributes packets with different QoS requirements to DRBs with different priorities. SDAP entity submits SDAP PDUs to lower layer after other packet handling procedure.

Figure 6 illustrate an exemplary flowchart for PDCP to receive SDAP PDUs with XR traffic and set different discardtimer to different DRBs by RRC indication in accordance with embodiments of the current invention. In one embodiment, one SDAP entity associates with two PDCP entities with different DRBs. After SDAP packet inspection and packet classification, PDCP entities received SDAP PDUs from DRBs with different priorities. In one embodiment, PDCP set different discardtimer value to different DRBs by RRC indication. The mapping rules between DRB identity and discardtimer value is included in PDCP-Config information element and indicated to UE through RRC reconfiguration message. For PDCP entity with higher priority XR packets, the PDCU SDU will be discarded after a longer waiting time for higher reliability. PDCP entities submit PDCP PDUs to lower layer after other packet handling procedure.

Figure 7 illustrate an exemplary flowchart for RLC to receive PDCP PDUs with XR traffic from different DRBs and map to logical channels with different LCIDs by RRC indication in accordance with embodiments of the current invention. RLC entities receive PDCP PDUs from PDCP entities with different DRBs and map to different logical channels. In one embodiment, each logical channel is corresponding to a RLC entity. The mapping rules between DRB identity and LCID is included in RLC-BearerConfig information element and indicated to UE through RRC reconfiguration message. RLC entities submit RLC PDUs to lower layer after other packet handling procedure.

Figure 8 illustrate an exemplary flowchart for MAC to prioritizes RLC PDUs with XR traffic from different logical channels and multiplexes to MAC PDUs by RRC indication. In one embodiment, The MAC PDU with higher priority SDUs will be perform blind HARQ retransmission in accordance with embodiments of the current invention. MAC entity receives RLC PDUs from logical channels with different priorities. Logical channel priority and related parameters (e.g., PBR and BSD) are included in LogicalChannelConfig information element and indicated to UE through RRC reconfiguration message. The Logical Channel Prioritization (LCP) procedure is applied then XR packets are multiplexed to MAC PDUs. In one embodiment, RLC PDUs with different priorities can be multiplexed to different MAC PDUs or the same MAC PDU. MAC submit MAC PDUs to HARQ entities after multiplexing and assembly procedure. In one embodiment, TBs with different priority SDUs are delivered to different HARQ process for HARQ operation. For TBs with higher priority SDUs, blind HARQ retransmission is performed for reliability enhancement. MAC entity submits MAC PDUs to lower layer after other packet handling procedure.

Figure 9 illustrates an exemplary process of an XR traffic packet handling at Internet layers and radio access layer with SDAP based packet inspection and classification mechanism in accordance with embodiments of the current invention. In one embodiment, XR traffic is consist of I frames (represent critical frames) and P frames (represent non-critical frames) . Frame fragmentation is performed at real time transport layer (e.g., RTP) , while XR payload type and other information are put into the header of the transport layer. After packet handling, RTP packets are delivered to UDP/IP layer for packet forwarding. The type of service (XR traffic) is indicated by DSCP in IP header.

In one embodiment, SDAP inspects the header of transport layer to check RTP payload type after receiving QoS flow with XR traffic from upper layer, and then distributes packets with different QoS requirements to DRBs with different priorities. In one embodiment, packets with I frame are distribute to DRB with DRB ID=1 (represent high priority) , packets with P frame are distribute to DRB with DRB ID=2 (represent low priority) . In one embodiment, the mapping rules between DRB IDs and priorities are indicated by RRC signaling.

After SDAP packet handling, SDAP PDUs are submitted to PDCP layer. In one embodiment, one SDAP entity is associate with two PDCP entities to handle DRBs with different priorities. In one embodiment, PDCP entities set different discardtimer value according to their priorities. PDCP SDU with I frame are set with longer waiting time (discardtimer value=X) before SDU discarding for higher reliability. In one embodiment, the mapping rule between DRB IDs and timer value is indicated by RRC signaling.

After PDCP packet handling, PDCP PDUs are submitted to RLC layer. RLC entities map PDCP PDUs from different DRBs to logical channels with different LCIDs. In one embodiment, the mapping rule between DRB IDs and timer value is indicated by RRC signaling. DRB ID=1 is map to LCID=M for higher reliability, and DRB ID=2 is map to LCID=N for lower reliability.

After RLC packet handling procedure, RLC PDUs are submitted to MAC layer. MAC entity multiplexes and assembles RLC PDUs from different logical channel (with different priority) to MAC PDUs. In one embodiment, one MAC PDU only consists of MAC SDUs of the same logical channel (e.g., TB2 only consists of MAC SDUs with P frame of XR traffic from LCID=N) . In one embodiment, one MAC PDU consists of MAC SDUs of different logical channels (e.g., TB1 consists of MAC SDUs with both I frame and P frame of XR traffic from LCID=M and N) . After multiplexing and assembly procedure, MAC PDUs are delivered to different HARQ process for HARQ operation. In one embodiment, blind HARQ retransmission is performed to MAC PDUs with higher priority for reliability enhancement. (e.g., TB1, consists of MAC SDUs with I frame and P frame of XR traffic, is retransmitted before ACK/NACK feedback) . After MAC packet handling procedure, MAC PDUs are submitted to lower layer.

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 transmit and receive the XR services with packet awareness mechanism via packet inspection and classification procedure, wherein the packet inspection is based on SDAP layer, while packet classification and related packet handling procedures involve SDAP, PDCP, RLC and MAC layer, comprising the steps of:

On the transmitting side of uplink transmission,

SDAP inspect the header of transport layer and know the packet characteristic;

SDAP maps the QoS flow to multiple DRBs to classify packets with different QoS requirements;

PDCP received SDAP PDUs from DRBs with different priorities;

RLC maps different DRBs to logical channels with different LCIDs;

MAC multiplexes and assembles RLC PDUs with different LCIDs to MAC PDUs;

On the receiving side of downlink transmission,

each layer configures the receiving procedure consistent with the transmitting side (gNB) .
The method of claim 1, wherein the SDAP based packet inspection is performed by checking the DSCP value of IP header; RTP payload type will then be checked for packet’s QoS requirement if DSCP value consistent with XR traffic.
The method of claim 1, further comprising the PDCP entity configures different discardtimer to DRBs with different QoS requirement.
The method of claim 1, further comprising the MAC entity distributes MAC PDUs to different HARQ entities according to the priority of MAC SDUs; TBs with high priority SDUs are performed blind HARQ retransmission without feedback.
The method of claim 1, wherein the one or more values for the configuration of SDAP, PDCP, RLC, MAC are provided by RRCSetup.
The method of claim 1, wherein the one or more values for the configuration of SDAP, PDCP, RLC, MAC are provided by RRCResume.
The method of claim 1, wherein the one or more values for the configuration of SDAP, PDCP, RLC, MAC are provided by RRCReconfiguration.