The disclosed embodiments relate generally to wireless communication, and, more particularly, to method of UE route selection policy (URSP) procedure enhancement for 4G evolved packet system (EPS).
The 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 (5GS).
The UE policies for 5GS include UE route selection policy (URSP) and access network discovery and selection policy (ANDSP). The UE policies can be delivered from a Policy Control Function (PCF) to UE. PCF takes care of network policies to manage network behavior. PCF gets the subscription information from Unified Data Management (UDM). PCF interfaces to both Access and Mobility Function (AMF) to manage the mobility context and Session Management Function (SMF) to manage the session contexts. PCF also plays a crucial role in providing a schema for network slicing and roaming. PCF triggers the URSP which enables the UE to determine how a certain application should be handled in the context of an existing or new PDN connection in EPS or PDU session in 5GS.
In 4G evolved packet system (EPS), a Packet Data Network (PDN) connectivity procedure is an important process when LTE communication system accesses to the packet data network. The purpose of PDN connectivity procedure is to setup a default EPS bearer between a UE and the packet data network. In 5G, a Protocol Data Unit (PDU) session establishment is a parallel procedure of the PDN connectivity procedure in 4G. A PDU session defines the association between the UE and the data network that provides a PDU connectivity service. When an application is executed, the upper layer of the UE sends the application information to the URSP entity for matching a URSP rule (i.e., by evaluating the traffic descriptor), and use the corresponding RSD (Route Selection Descriptor) of the selected URSP rule to associate with an existing PDU session or to establish a new PDU session. The UE tries to reuse an existing PDU session.
The concept of “redundant PDU session” is introduced for URLLC (Ultra Reliable and Low Latency Communication) applications in 5G. The 5GSM sublayer may support establishment of redundant PDU sessions. In order to establish a set of two redundant PDU sessions, a UE can include a PDU session pair ID, an RSN, or both in a PDU SESSION ESTABLISHMENT REQUEST message for each of the two redundant PDU sessions. The UE can set the PDU session pair ID, the RSN, or both according to URSP or UE local configuration. In addition, an SMF can handle two PDU sessions as redundant even if the UE provides neither a PDU session pair ID nor an RSN in a PDU SESSION ESTABLISHMENT REQUEST message for each PDU session.
While the URSP mechanism can be executed in EPS, “PDU session pair ID” or “RSN” of the redundant PDU session, however, is not supported in EPS. When the RSD of a selected URSP rule comprising parameters for redundant PDU session, e.g., “PDU session pair ID type”, and/or “a redundancy sequency number (RSN) type” is evaluated, it is not defined on how UE should handle the specific RSD components intended only for redundant PDU sessions.
A solution is sought.
A method for UE route selection policy (URSP) rule matching enhancement in an evolved packet system (EPS) is proposed. When an application is executed, the upper layer of a UE sends the application information to URSP entity for matching a URSP rule. The UE selects and evaluates a route selection descriptor (RSD) from a list of RSDs of a selected URSP rule to be matched with a PDN connection. If there is a “PDU session pair ID type” and/or “RSN type” route selection descriptor components in an RSD, such RSD components are intended for a redundant PDU session, which is not supported in EPS. Therefore, the UE ignores the specific RSD components and continues to evaluate the RSD with the remaining RSD components. In one example, the UE finds the traffic descriptor in the selected URSP rule matching the application and an existing PDN connection matching at least one of the RSDs of the selected URSP rule, even though the RSD comprises a “PDU session pair ID type” and/or “RSN type” components.
In one embodiment, a UE initiates a UE Route Selection Policy (URSP) rule matching procedure in an evolved packet system (EPS) mobile communication network. The UE selects a URSP rule from one or more URSP rules. The UE matches a traffic descriptor of the selected URSP rule with an application information. The UE selects and evaluating a route selection descriptor (RSD) from a list of RSDs of the selected URSP rule to be matched with a PDN connection. The RSD has a list of stored RSD components comprising a PDU session pair ID or a redundancy sequency number (RSN). The UE ignores the PDU session pair ID or ignores the RSN or skips both components for the RSD evaluation. The UE continues with the RSD evaluation for the URSP rule matching procedure in EPS.
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. When UE joins a 5GS network, a PDU address (i.e., the one that can be used on the PDU) is assigned to the UE for its connection to the PDU. In 4G, EPS has defined a Default EPS Bearer to provide the IP Connectivity. In 5G, a Protocol Data Unit (PDU) session establishment procedure is a parallel procedure of a PDN connection procedure in 4G. A PDU session (e.g., 130) 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.
The UE policies for 5GS include UE route selection policy (URSP) and access network discovery and selection policy (ANDSP). The UE policies can be delivered from Policy Control Function (PCF) to UE. PCF takes care of network policies to manage network behavior. PCF gets the subscription information from Unified Data Management (UDM). PCF interfaces to both Access and Mobility Function (AMF) to manage the mobility context and Session Management Function (SMF) to manage the session contexts. PCF also plays a crucial role in providing a scheme for network slicing and roaming. PCF provisions the URSP which enables the UE to determine how a certain application should be handled in the context of an existing or new PDU session. The UE policies can also be pre-configured in the UE (USIM or NVRAM). The pre-configured policy should be applied by UE only when UE has not received the same type of policy from the PCF.
The concept of “redundant PDU session” is introduced for URLLC (Ultra Reliable and Low Latency Communication) applications. The 5GSM sublayer may support establishment of redundant PDU sessions. In order to establish a set of two redundant PDU sessions, a UE can include a PDU session pair ID, an RSN, or both in a PDU SESSION ESTABLISHMENT REQUEST message for each of the two redundant PDU sessions. The UE can set the PDU session pair ID, the redundancy sequency number (RSN), or both according to URSP or UE local configuration. While URSP is a 5G technique that allows the PCF to provision UE with rules related to data routing, such URSP mechanism in 5GS can be executed in EPS. The concept of “PDU session pair ID” or “RSN” of redundant PDU session, however, is not applicable in EPS.
In one novel aspect, a method for UE route selection policy (URSP) rule matching enhancement in EPS is proposed. In 5GS, the URSP mechanism is depicted by 140. When an application is executed, the upper layer of a UE sends the application information to URSP entity for matching a URSP rule with traffic descriptor (141). The UE selects and evaluates a route selection descriptor (RSD) from a list of RSDs of a selected URSP rule to be matched with a PDU session (142). In one example, the UE finds the traffic descriptor in the selected URSP rule matching the application and an existing PDU session matching at least one of the RSDs of the selected URSP rule.
In EPS, the URSP mechanism is depicted by 150. When an application is executed, the upper layer of a UE sends the application information to URSP entity for matching a URSP rule with traffic descriptor (151). The UE selects and evaluates a route selection descriptor (RSD) from a list of RSDs of a selected URSP rule to be matched with a PDN connection (152). If there is a “PDU session pair ID type” and/or “RSN type” route selection descriptor components in an RSD, such RSD components are intended for a redundant PDU session, which is not supported in EPS. Therefore, the UE ignores the specific RSD components and continues with URSP matching for remaining RSD components. In one example, the UE finds the traffic descriptor in the selected URSP rule matching the application and an existing PDN connection matching at least one of the RSDs of the selected URSP rule, even though the RSD comprises a “PDU session pair ID type” and/or “RSN type” components for redundant PDU session.
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 microprocessors, 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 application layer and other upper layers to manage different applications, 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, the upper layer entities request information of the PDU session via which to send a PDU of an application, system modules and circuits 270 comprise a PDU session/PDN connection handling circuit 221 that performs PDU session/PDN connection establishment and modification procedures with the network, a URSP rule matching circuit 222 that performs URSP rule matching, and a configuration and control circuit 223 that handles configuration and control parameters for mobility management and session management.
Each route selection descriptor includes a precedence value of the route selection descriptor and either 1) one PDU session type and, optionally, one or more of the followings: A) session and service continuity (SSC) mode; B) one or more S-NSSAIs; C) one or more DNNs; D) PDU session type; E) preferred access type; F) multi-access preference; G) time window; H) location criteria; I) PDU session pair ID; and J) RSN; or 2) non-seamless non-3GPP offload indication. Only one URSP rule in the URSP can be a default URSP rule and the default URSP rule should contain a match-all traffic descriptor. If a default URSP rule and one or more non-default URSP rules are included in the URSP, any non-default URSP rule should have lower precedence value (i.e., higher priority) than the default URSP rule.
URSP is used by the UE to determine if a detected application can be associated to an established PDU session, can be offload to non-3GPP access outside a PDU session, or can trigger the establishment of a new PDU session. A URSP rule includes one traffic descriptor that specifies the matching criteria and one or more of the following RSD components associated with a precedence value: SSC mode selection policy to associated the matching application with SSC mode, network slice selection policy to associated the matching application with S-NSSAI, DNN selection policy to associated the matching application with DNN, PDU session type policy to associated the matching application with a PDU session, time window, location criteria, preferred access type indicating a preferred access (3GPP or non-3GPP) when UE needs to establish a new PDU session for the matching application, multi-access preference type for MA PDU, PDU session pair ID for redundant PDU session, RSN, and non-seamless offload policy to determine that the matching application should be non-seamlessly offloaded to non-3GPP access (i.e., out of a PDU session).
In one novel aspect, when performing URSP rule matching with an application in EPS, the UE matches a traffic descriptor (TD) of a selected URSP rule. The UE then selects a route selection descriptor (RSD) and determines whether the RSD includes a “PDU session pair ID type” or “RSN type” route selection descriptor component or both. If so, then the UE knows that those RSD components are intended to be associated with a redundant PDU session and not applicable for PDN connection in EPS. In order to match the RSD with a PDN connection in EPS, the UE ignores or skips those specific RSD components, e.g., “PDU session pair ID” and “RSN”. As a result, this RSD can still be selected by the UE to be associated with an existing PDN connection for URSP rule matching.
As depicted in
In one novel aspect, the UE also checks whether there are any RSD components for redundant PDU session. For example, the UE determines whether RSD1 includes a “PDU session pair ID type” or “RSN type” route selection descriptor component or both components. If so, then the UE knows that RSD1 is intended to be associated with a redundant PDU session in 5GS, and those RSD components are not applicable for PDN connection in EPS. In one novel aspect, the UE ignores or skips those specific RSD components, e.g., “PDU session pair ID” and “RSN” and continues to evaluate the RSD1 with the remaining RSD components. In one example, by skipping those specific RSD components, the UE finds the TD in URSP rule N+1 matching the application information, and an established PDN connection matching RSD1 of the URSP rule N+1, the UE then provides information on the PDN connection that matches RSD1 to the upper layers. If there is no matched existing PDN, the URSP layer selects RSD from smallest precedence value and check and send request with the parameters(D) PDU session type; E) preferred access type;) in RSD to the NAS layer.
On the other hand, if the UE does not ignore those specific RSD components in RSD1, then the UE will not find RSD1 to be a match to a PDN connection. The UE will then select an RSD (e.g., RSD2) with the next smallest precedence value within URSP rule N+1 which has not been evaluated. The UE may select another RSD or URSP rule that does not best fit the application. Further, the UE may try to establish a new PDN connection. If the PDN connection establishment fails, the UE may continue to retry and wasting time and resource.
In step 520, UE 501 tries all non-default URSP rules in an order of the precedence values. Specifically, in step 521, UE 501 selects a matching URSP rule, and then either finds existing PDU session/PDN connection, or establishes new PDU session/PDN connection, that matches at least one of the route selection descriptors of the selected URSP rule. If no matching exists, the UE NAS layer then attempts to establish a new PDU session/PDN connection. For example, in step 522, UE 501 sends a PDN connectivity establishment request to the network. In step 523, the network sends a PDN connectivity establishment accept to UE 501 and the PDN connection is established successfully. Otherwise, the network sends a PDN connectivity establishment reject to UE 501 and the PDN connection is not established. After step 520, if all non-default URSP rules cannot be matched with the application, then in step 531, UE 501 tries the default URSP rule, which includes a match-all traffic descriptor. If the association is still unsuccessful, then UE 501 informs the upper layers of the failure.
If the above URSP procedure is executed in EPS, then in step 521, UE 501 also checks whether there are any RSD components for redundant PDU session. For example, the UE determines whether an RSD of a selected URSP rule includes a “PDU session pair ID type” or “RSN type” route selection descriptor component or both components. If so, then the UE knows that the RSD is intended to be associated with a redundant PDU session in 5GS, and those RSD components are not applicable for PDN connection in EPS. In one novel aspect, the UE ignores or skips those specific RSD components of the RSD, e.g., “PDU session pair ID” and “RSN” and continues with the evaluation and matching between PDN connection and the remaining components of the RSD. If an existing PDN connection matches with the remaining RSD components, then the UE provides information on the PDN connection that matches the RSD of the selected URSP rule to the upper layers. If the UE didn’t find any existing PDN matches with the RSD components, the UE send the applicable parameters (DNN(APN), PDU(PDN) type) in step 522.
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.
This application claims priority under 35 U.S.C. §119 from U.S. Provisional Application Number 63/250,304, entitled “URSP Enhancement for EPS”, filed on Sep. 30, 2021, the subject matter of which is incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
63250304 | Sep 2021 | US |