Handling QoS Flow without a Mapping Data Radio Bearer
A PDU session and QoS flow handling mechanism is proposed when a QoS flow of a PDU session does not have a mapping DRB after a handover or a service request procedure. If the QoS flow is associated with a default QoS rule, the UE can locally release the PDU session, initiate a PDU session release procedure, send a 5GSM status message with proper cause, or assume the PDU session is not reactivated. On the other hand, if the QoS flow is not associated with a default QoS rule, the UE can locally delete the QoS flow, delete the QoS flow by using a PDU session modification procedure, or send a 5GSM status message with proper cause.
This application claims priority under 35 U.S.C. § 119 from U.S. Provisional Application No. 62/655,137, entitled “5GSM Enhancement on Interworking”, filed on Apr. 9, 2018, the subject matter of which is incorporated herein by reference.
TECHNICAL FIELDThe disclosed embodiments relate generally to wireless communication, and, more particularly, to method of handling Quality of Service (QoS) flows without a mapping data radio bearer (DRB) in 5G new radio (NR) systems.
BACKGROUNDThe wireless communications network has grown exponentially over the years. A Long-Term Evolution (LTE) system offers high peak data rates, low latency, improved system capacity, and low operating cost resulting from simplified network architecture. LTE systems, also known as the 4G system, also provide seamless integration to older wireless network, such as GSM, CDMA and Universal Mobile Telecommunication System (UMTS). In LTE systems, an evolved universal terrestrial radio access network (E-UTRAN) includes a plurality of evolved Node-Bs (eNodeBs or eNBs) communicating with a plurality of mobile stations, referred to as user equipments (UEs). The 3rd generation partner project (3GPP) network normally includes a hybrid of 2G/3G/4G systems. The Next Generation Mobile Network (NGMN) board, has decided to focus the future NGMN activities on defining the end-to-end requirements for 5G new radio (NR) systems.
In 5G, a Protocol Data Unit (PDU) session establishment is a parallel procedure of a Packet Data Network (PDN) connection procedure in 4G. A PDU session defines the association between the UE and the data network that provides a PDU connectivity service. Each PDU session is identified by a PDU session ID, and may include multiple QoS flows and QoS rules. In 5G network, QoS flow is the finest granularity for QoS management to enable more flexible QoS control. The concept of QoS flow in 5G is like EPS bearer in 4G. Each QoS flow is identified by a QoS flow ID (QFI) which is unique within a PDU session. Each QoS rule is identified by a QoS rule ID (QRI). There can be more than one QoS rule associated with the same QoS flow. A default QoS rule is required to be sent to the UE for every PDU session establishment and it is associated with a QoS flow.
Each QoS flow needs to be supported by a mapping Data Radio Bearer (DRB) in Access Stratum (AS) layer. Multiple QoS flows can be mapped to the same DRB. If there is a default DRB for a PDU session, then all traffic of QoS flows that have no mapping DRBs are sent via the default DRB. After an intra-system or inter-system handover procedure, or after a UE-initiated or network-initiated service request procedure, the RRC/AS layer may indicate that a QoS flow is not supported, e.g., the mapping DRB for the QoS flow is not established, or the mapping for the QoS flow to a DRB is missing and there is no default DRB available.
A solution is sought to properly handle PDU session and QoS flow management when UE cannot find a mapping DRB for a QoS flow of a PDU session after a handover procedure or a service request procedure.
SUMMARYA PDU session and QoS flow handling mechanism is proposed when a QoS flow of a PDU session does not have a mapping DRB after a handover or a service request procedure. If the QoS flow is associated with a default QoS rule, then all QoS flows of the PDU session is impacted and corresponding action is thus required for the PDU session. Specifically, the UE can locally release the PDU session, initiate a PDU session release procedure, send a 5GSM status message with proper cause, or assume the PDU session is not reactivated. On the other hand, if the QoS flow is not associated with a default QoS rule, then only this particular QoS flow is impacted and corresponding action is thus required for the QoS flow. Specifically, the UE can locally delete the QoS flow, delete the QoS flow by using a PDU session modification procedure, or send a 5GSM status message with proper cause.
In one embodiment, a UE receives a radio resource control (RRC) reconfiguration in a mobile communication network. The UE is configured with one or more Protocol data unit (PDU) sessions, and an activated PDU session is configured with one or more QoS flows. The UE detects that a QoS flow of the activated PDU session has no mapping data radio bearer (DRB) available based on the RRC reconfiguration. The UE performs a first PDU session and QoS flow handling when the QoS flow is associated with a default QoS rule. The UE performs a second PDU session and QoS flow handing when the QoS flow is not associated with the default QoS rule. In one embodiment, the UE locally releases the PDU session, initiates a PDU session release procedure, sends a 5GSM status message with proper cause, or assumes the PDU session is not reactivated when the QoS flow is associated with the default QoS rule. In another embodiment, the UE locally deletes the QoS flow, deletes the QoS flow by using a PDU session modification procedure, or sends a 5GSM status message with proper cause when the QoS flow is not associated with the default QoS rule.
Other embodiments and advantages are described in the detailed description below. This summary does not purport to define the invention. The invention is defined by the claims.
The accompanying drawings, where like numerals indicate like components, illustrate embodiments of the invention.
Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawings.
5GS networks are packet-switched (PS) Internet Protocol (IP) networks. This means that the networks deliver all data traffic in IP packets, and provide users with Always-On IP Connectivity. When UE joins a 5GS network, a Packet Data Network (PDN) address (i.e., the one that can be used on the PDN) is assigned to the UE for its connection to the PDN. In 4G, EPS has defined a Default EPS Bearer to provide the IP Connectivity that is Always-On. In 5G, a Protocol Data Unit (PDU) session establishment procedure is a parallel procedure of a PDN connection procedure in 4G. A PDU session defines the association between the UE and the data network that provides a PDU connectivity service. Each PDU session is identified by a PDU session ID, and may include multiple QoS flows and QoS rules. In 5G network, QoS flow is the finest granularity for QoS management to enable more flexible QoS control. The concept of QoS flow in 5G is like EPS bearer in 4G. Each QoS flow is identified by a QoS flow ID (QFI) which is unique within a PDU session. Each QoS rule is identified by a QoS rule ID (QRI). There can be more than one QoS rule associated with the same QoS flow. A default QoS rule is required to be sent to the UE for every PDU session establishment and it is associated with a QoS flow.
In the example of
In accordance with one novel aspect, a PDU session and QoS flow handling mechanism is proposed when a QoS flow of a PDU session does not have a mapping DRB after a handover or a service request procedure. If the QoS flow is associated with a default QoS rule, then all QoS flows of the PDU session is impacted and corresponding action is thus required for the PDU session. Specifically, the UE can locally release the PDU session, initiate a PDU session release procedure, send a 5GSM status message with proper cause, or assume the PDU session is not reactivated. On the other hand, if the QoS flow is not associated with a default QoS rule, then only this particular QoS flow is impacted and corresponding action is thus required for the QoS flow. Specifically, the UE can locally delete the QoS flow, delete the QoS flow by using a PDU session modification procedure, or send a 5GSM status message with proper cause.
Similarly, UE 201 has memory 202, a processor 203, and radio frequency (RF) transceiver module 204. RF transceiver 204 is coupled with antenna 205, receives RF signals from antenna 205, converts them to baseband signals, and sends them to processor 203. RF transceiver 204 also converts received baseband signals from processor 203, converts them to RF signals, and sends out to antenna 205. Processor 203 processes the received baseband signals and invokes different functional modules and circuits to perform features in UE 201. Memory 202 stores data and program instructions 210 to be executed by the processor to control the operations of UE 201. Suitable processors include, by way of example, a special purpose processor, a digital signal processor (DSP), a plurality of micro-processors, one or more micro-processor associated with a DSP core, a controller, a microcontroller, application specific integrated circuits (ASICs), file programmable gate array (FPGA) circuits, and other type of integrated circuits (ICs), and/or state machines. A processor in associated with software may be used to implement and configure features of UE 201.
UE 201 also comprises a set of functional modules and control circuits to carry out functional tasks of UE 201. Protocol stacks 260 comprise Non-Access-Stratum (NAS) layer to communicate with an AMF entity connecting to the core network, Radio Resource Control (RRC) layer for high layer configuration and control, Packet Data Convergence Protocol/Radio Link Control (PDCP/RLC) layer, Media Access Control (MAC) layer, and Physical (PHY) layer. System modules and circuits 270 may be implemented and configured by software, firmware, hardware, and/or combination thereof. The function modules and circuits, when executed by the processors via program instructions contained in the memory, interwork with each other to allow UE 201 to perform embodiments and functional tasks and features in the network. In one example, system modules and circuits 270 comprise PDU session handling circuit 221 that performs PDU session establishment and modification procedures with the network, a QoS rule management circuit 222 that manages, creates, modifies, and deletes QoS flows and QoS rules, a config and control circuit 223 that handles configuration and control parameters for mobility management and session management.
In step 321, UE 301 camps on the target NR cell. In step 331, UE 301 sends a handover complete to the target base station NR gNB 305. The handover complete comprises an RRC reconfiguration complete message. In step 341, the AS layer of UE 301 sends DRB information forwarding to the NAS layer of UE 301. This is an internal signaling and the information is mainly based on the content of the RRC reconfiguration message. In step 351, UE 301 performs PDU session and QoS flow handling after the handover is completed. In accordance with one novel aspect, UE 301 determines which PDU session is to be reactivated upon the handover, and whether each QoS flow of the reactivated PDU session is supported by a mapping DRB. If there is unsupported QoS flow(s), then UE 301 will further determine whether the QoS flow is associated with a default QoS rule or not, and perform corresponding action.
If the QoS flow is associated with the default QoS rule, then the entire PDU session is impacted. As a result, the UE needs to handle the PDU session accordingly. In a first option (step 421), the UE release the PDU session implicitly or explicitly. If implicitly, the UE releases the PDU session locally, and optionally initiate a registration procedure for synchronization with the network. If explicitly, the UE initiates a PDU session release procedure to release the PDU session. In a second option (422), the UE sends 5GSM status message with proper cause to inform the network. In a third option (423), the UE assumes the PDU session is not reactivated, and optionally initiates a registration procedure with the network for synchronization.
If the QoS flow is not associated with the default QoS rule, then only the QoS flow is impacted. As a result, the UE needs to handle the QoS flow accordingly. In a first option (431), the UE deletes the QoS flow implicitly or explicitly. If implicitly, the UE deletes the QoS flow locally, and optionally sends a PDU session modification to the network. If explicitly, the UE deletes the QoS flow by using a PDU session modification procedure. In a second option (432), the UE sends 5GSM status message with proper cause to inform the network. In a third option (433), the UE assumes the QoS flow is not reactivated, and optionally initiates a registration procedure with the network for synchronization.
In step 531, the target RAN 505 sends an RRC reconfiguration message to the AS layer of UE 501 in response to the service request. From AS layer point of view, the RRC reconfiguration message comprises radio bearer configuration, which adds DRBs and associated PDU sessions/QoS flows. Note that the RAN may send multiple RRC reconfiguration messages subsequently, e.g., another RRC reconfiguration message in step 532. Each RRC reconfiguration message may provide additional radio bearer configuration for UE 501. As a result, UE 501 may need to wait for some time in order to receive all the RRC reconfiguration messages. In step 541, the AS layer of UE 501 sends DRB information forwarding to the NAS layer of UE 501. This is an internal signaling and the information is mainly based on the content of the RRC reconfiguration message(s). In step 551, UE 501 performs PDU session and QoS flow handling after the handover is completed. In accordance with one novel aspect, UE 501 determines which PDU session is to be reactivated upon the handover, and whether each QoS flow of the reactivated PDU session is supported by a mapping DRB. If there is unsupported QoS flow(s), then UE 501 will further determine whether the QoS flow is associated with a default QoS rule or not, and perform corresponding actions.
Although the present invention has been described in connection with certain specific embodiments for instructional purposes, the present invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.
Claims
1. A method, comprising:
- receiving a radio resource control (RRC) reconfiguration by a user equipment (UE) in a mobile communication network, wherein the UE is configured with one or more Protocol data unit (PDU) sessions, and wherein an activated PDU session is configured with one or more QoS flows;
- detecting that a QoS flow of the activated PDU session has no mapping data radio bearer (DRB) available based on the RRC reconfiguration;
- performing a first PDU session and QoS flow handling when the QoS flow is associated with a default QoS rule; and
- performing a second PDU session and QoS flow handing when the QoS flow is not associated with the default QoS rule.
2. The method of claim 1, wherein the RRC reconfiguration is due to an intra-system or inter-system handover procedure.
3. The method of claim 1, wherein RRC reconfiguration is due to a UE-initiated or a network-initiated service request procedure.
4. The method of claim 1, wherein the first PDU session and QOS handling involves releasing the activated PDU session locally by the UE.
5. The method of claim 1, wherein the first PDU session and QoS flow handling involves initiating a PDU session release procedure with the network.
6. The method of claim 1, wherein the first PDU session and QoS flow handling involves the UE treating the activated PDU session as not reactivated.
7. The method of claim 1, wherein the second PDU session and QoS flow handling involves deleting the QoS flow locally by the UE or explicitly by using a PDU session modification procedure.
8. The method of claim 1, wherein the second PDU session and QoS flow handling involves the UE treating the QoS flow as not reactivated.
9. The method of claim 1, wherein the UE detects that the QoS flow is mapped to a DRB but the DRB is not established after the RRC reconfiguration.
10. The method of claim 1, wherein the UE detects that a mapping between the QoS flow and any established DRB is missing and there is no default DRB available after the RRC reconfiguration.
11. A User Equipment (UE), comprising:
- a receiver that receives a radio resource control (RRC) reconfiguration in a mobile communication network, wherein the UE is configured with one or more Protocol data unit (PDU) sessions, and wherein an activated PDU session is configured with one or more QoS flows;
- a configure and control circuit that detects that a QoS flow of the activated PDU session has no mapping data radio bearer (DRB) available based on the RRC reconfiguration; and
- a QoS flow handling circuit that performs a first PDU session and QoS flow handling when the QoS flow is associated with a default QoS rule, otherwise performing a second PDU session and QoS flow handing when the QoS flow is not associated with the default QoS rule.
12. The UE of claim 11, wherein the RRC reconfiguration is due to an intra-system or inter-system handover procedure.
13. The UE of claim 11, wherein RRC reconfiguration is due to a UE-initiated or a network-initiated service request procedure.
14. The UE of claim 11, wherein the first PDU session and QOS handling involves releasing the activated PDU session locally by the UE.
15. The UE of claim 11, wherein the first PDU session and QoS flow handling involves initiating a PDU session release procedure with the network.
16. The UE of claim 11, wherein the first PDU session and QoS flow handling involves the UE treating the activated PDU session as not reactivated.
17. The UE of claim 11, wherein the second PDU session and QoS flow handling involves deleting the QoS flow locally by the UE or explicitly by using a PDU session modification procedure.
18. The UE of claim 11, wherein the second PDU session and QoS flow handling involves the UE treating the QoS flow as not reactivated.
19. The UE of claim 11, wherein the UE detects that the QoS flow is mapped to a DRB but the DRB is not established after the RRC reconfiguration.
20. The UE of claim 11, wherein the UE detects that a mapping between the QoS flow and any established DRB is missing and there is no default DRB available after the RRC reconfiguration.
Type: Application
Filed: Apr 3, 2019
Publication Date: Oct 10, 2019
Inventors: Chia-Chun Huang-Fu (Hsin-Chu), Chi-Hsien Chen (Hsin-Chu), Shang-Ru Mo (Hsin-Chu)
Application Number: 16/373,895