Patent Description:
Third generation partnership project (3GPP) and <NUM> New Radio (NR) mobile telecommunication systems provide high data rate, lower latency and improved system performances. In 3GPP NR, <NUM> terrestrial New Radio (NR) access network includes a plurality of base stations, e.g., Next Generation Node-Bs (gNBs), communicating with a plurality of mobile stations referred as user equipment (UEs). Orthogonal Frequency Division Multiple Access (OFDMA) has been selected for NR downlink radio access scheme due to its robustness to multipath fading, higher spectral efficiency, and bandwidth scalability. Multiple access in the downlink is achieved by assigning different sub-bands (i.e., groups of subcarriers, denoted as resource blocks (RBs)) of the system bandwidth to individual users based on their existing channel condition.

Operators are seeking ways to balance data traffic between mobile networks and non-3GPP access in a way that is transparent to users and reduces mobile network congestion. In 5GS, UEs can be simultaneously connected to both 3GPP access and non-3GPP access (using non-access stratum (NAS) signalling), thus the 5GS is able to take advantage of these multiple accesses to improve the user experience and optimize the traffic distribution across various accesses. Accordingly, UE can register to one or more networks over 3GPP access, over non-3GPP access, or over both 3GPP and non-3GPP. For example, 3GPP document <NUM>-H71 discloses Non-Access Stratum protocol for <NUM> system.

After UE transmits a REGISTRATION REQUEST message to the network, UE receives a REGISTRATION ACCEPT message, which carries a 5GS registration result value in the 5GS registration result IE. If the 5GS registration result value indicates "3GPP access", the UE consider itself as being registered to 3GPP access only. If the 5GS registration result value indicates "non-3GPP access", the UE consider itself as being registered to non-3GPP access only. If the 5GS registration result value indicates "3GPP access and non-3GPP access", the UE consider itself as being registered to both 3GPP access and non-3GPP access. However, the 5GS registration result value received over a first access may not indicate the UE registration status for a second access.

This invention aims at providing a method of determining UE registration status for a UE that is registered to networks over 3GPP and non-3GPP accesses. This is achieved by methods and a UE according to claims <NUM>, <NUM> and <NUM>, respectively. The dependent claims pertain to corresponding further developments and improvements.

As will be seen more clearly from the detailed description below, the claimed UE triggers registration to a Public Land Mobile Network (PLMN) or Standalone Non-Public Network (SNPN) over a second access, and receives a REGISTRATION ACCEPT message from the network over the second access. The REGISTRATION ACCEPT message carries a 5GS registration result IE having a 5GS registration result value. In case <NUM>, UE is not registered to a first network over a first access. However, the registration result value indicates BOTH the first access AND the second access, which is inaccurate. Accordingly, UE should ignore the registration result value and considers itself NOT registered to the first access. In case <NUM>, UE is registered to a first network over a first access. However, the registration result value indicates the second access ONLY, which is inaccurate. Accordingly, UE should ignore the registration result value and considers itself registered to BOTH the first access AND the second access. In case <NUM>, UE triggers registration to a first network over a first access. However, the registration result value indicates the second access ONLY. Accordingly, UE should ignore the registration result value and considers itself registered to the first access ONLY or to BOTH the first access AND the second access.

In the following, the invention is further illustrated by way of example, taking reference to the following drawings.

<FIG> illustrates an exemplary <NUM> network <NUM> and a method of determining registration status when a User Equipment (UE) is registered to the same or different networks over 3GPP access and non-3GPP access in accordance with one novel aspect. <NUM> new radio (NR) network <NUM> comprises a user equipment (UE) <NUM>, a 3GPP access <NUM> (e.g., a 3GPP radio access network (RAN)), a non-3GPP access <NUM> (e.g., a non-3GPP RAN), an access and mobility management function (AMF) <NUM>, a session management function (SMF) <NUM>, a non-3GPP interworking function (N3IWF) <NUM>, a user plane function (UPF) <NUM>, and a <NUM> core (5GC) data network <NUM>. The AMF <NUM> communicates with the base stations in the 3GPP access <NUM>, the SMF <NUM>, and the UPF <NUM> for access and mobility management of wireless access devices in the <NUM> network <NUM>. SMF <NUM> is primarily responsible for interacting with the decoupled data plane, creating, updating, and removing PDU sessions and managing session context with the UPF <NUM>. N3IWF <NUM> interfaces to <NUM> core network control plane functions, responsible for routing messages outside <NUM> RAN.

In Access Stratum (AS) layer, an RAN provides radio access for the UE <NUM> via a radio access technology (RAT). In Non-Access Stratum (NAS) layer, the AMF <NUM> and the SMF <NUM> communicate with RAN and 5GC for access and mobility management and PDU session management of wireless access devices in the <NUM> network <NUM>. The 3GPP access <NUM> may include base stations (gNBs or eNBs) providing radio access for the UE <NUM> via various 3GPP RATs including <NUM>, <NUM>, and <NUM>/<NUM>. The non-3GPP access <NUM> may include access points (APs) providing radio access for the UE <NUM> via non-3GPP RAT including WiFi. The UE <NUM> can obtain access to data network <NUM> through 3GPP access <NUM>, AMF <NUM>, SMF <NUM>, and UPF <NUM>. The UE <NUM> can obtain access to data network <NUM> through non-3GPP access <NUM>, N3IWF <NUM>, AMF <NUM>, SMF <NUM>, and UPF <NUM>. The UE <NUM> may be equipped with a single radio frequency (RF) module or transceiver or multiple RF modules or transceivers for services via different RATs/CNs. In some examples, UE <NUM> may be a smart phone, a wearable device, an Internet of Things (IoT) device, a tablet, etc..

In 5GS, UEs can be simultaneously connected to both 3GPP access and non-3GPP access (using non-access stratum (NAS) signalling), thus the 5GS is able to take advantage of these multiple accesses to improve the user experience and optimize the traffic distribution across various accesses. Accordingly, a UE can register to one or more networks in 5GS over 3GPP access, over non-3GPP access, or over both 3GPP and non-3GPP. After UE transmits a REGISTRATION REQUEST message to the network, UE receives a REGISTRATION ACCEPT message, which carries a 5GS registration result value in the 5GS registration result IE. If the 5GS registration result value indicates "3GPP access", the UE consider itself as being registered to 3GPP access only. If the 5GS registration result value indicates "non-3GPP access", the UE consider itself as being registered to non-3GPP access only. If the 5GS registration result value indicates "3GPP access and non-3GPP access", the UE consider itself as being registered to both 3GPP access and non-3GPP access. However, the 5GS registration result value received over a first access may not accurately indicate the UE registration status for a second access, especially when the UE is registered to different networks.

In accordance with one novel aspect, a method of determining UE registration status for a UE that is registered to networks over 3GPP and non-3GPP accesses is proposed. As depicted in <FIG> (<NUM>), UE <NUM> may send a REGISTRATION REQUEST message to a Public Land Mobile Network (PLMN) or Standalone Non-Public Network (SNPN) over a second access, and receives a REGISTRATION ACCEPT message from the network over the second access. The REGISTRATION ACCEPT message carries a 5GS registration result IE having a 5GS registration result value. In case <NUM>, UE <NUM> is not registered to a first network over a first access. However, the registration result value indicates BOTH the first access AND the second access, which is inaccurate. Accordingly, UE <NUM> should ignore the registration result value and considers itself NOT registered to the first access. In case <NUM>, UE <NUM> is registered to a first network over a first access. However, the registration result value indicates the second access ONLY, which is inaccurate. Accordingly, UE <NUM> should ignore the registration result value and considers itself registered to BOTH the first access AND the second access. In case <NUM>, UE <NUM> triggers registration to a first network over a first access. However, the registration result value indicates the second access ONLY. Accordingly, UE <NUM> should ignore the registration result value and considers itself registered to the first access ONLY or to BOTH the first access AND the second access.

<FIG> illustrates simplified block diagrams of wireless devices, e.g., a UE <NUM> and a network entity <NUM> in accordance with embodiments of the current invention. Network entity <NUM> may be a base station and/or an AMF/SMF. Network entity <NUM> has an antenna <NUM>, which transmits and receives radio signals. A radio frequency RF transceiver module <NUM>, coupled with the antenna, receives RF signals from antenna <NUM>, converts them to baseband signals and sends them to processor <NUM>. RF transceiver <NUM> also converts received baseband signals from processor <NUM>, converts them to RF signals, and sends out to antenna <NUM>. Processor <NUM> processes the received baseband signals and invokes different functional modules to perform features in base station <NUM>. Memory <NUM> stores program instructions and data <NUM> to control the operations of base station <NUM>. In the example of <FIG>, network entity <NUM> also includes protocol stack <NUM> and a set of control function modules and circuits <NUM>. Protocol stacks <NUM> includes Non-Access-Stratum (NAS) layer to communicate with an AMF/SMF/MME 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. In one example, control function modules and circuits <NUM> includes a registration circuit <NUM> that handles registration procedures, a connection handling circuit <NUM> that handles signaling connections, and a configuration and control circuit <NUM> that provides different parameters to configure and control UE of related functionalities including registration and paging. The network entity <NUM> can be one 5GS network component or more than one 5GS network components (e.g., access network + AMF + N3IWF + SMF, etc.).

Similarly, UE <NUM> has memory <NUM>, a processor <NUM>, and radio frequency (RF) transceiver module <NUM>. RF transceiver <NUM> is coupled with antenna <NUM>, receives RF signals from antenna <NUM>, converts them to baseband signals, and sends them to processor <NUM>. RF transceiver <NUM> also converts received baseband signals from processor <NUM>, converts them to RF signals, and sends out to antenna <NUM>. Processor <NUM> processes the received baseband signals and invokes different functional modules and circuits to perform features in UE <NUM>. Memory <NUM> stores data and program instructions <NUM> to be executed by the processor to control the operations of UE <NUM>. 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 <NUM>.

UE <NUM> also includes protocol stacks <NUM> and a set of control function modules and circuits <NUM>. Protocol stacks <NUM> includes NAS layer to communicate with an AMF/SMF/MME entity connecting to the core network, RRC layer for high layer configuration and control, PDCP/RLC layer, MAC layer, and PHY layer. Control function modules and circuits <NUM> may be implemented and configured by software, firmware, hardware, and/or combination thereof. The control function modules and circuits, when executed by the processors via program instructions contained in the memory, interwork with each other to allow UE <NUM> to perform embodiments and functional tasks and features in the network. In one example, control function modules and circuits <NUM> includes a registration handling circuit <NUM> that performs registration procedure with the network, a connection handling circuit <NUM> that handles RRC and NAS signaling connection, and a config and control circuit <NUM> that handles configuration and control parameters including determining UE access identity. In one embodiment, the UE receives a registration result value from a second network over a second access that indicates a registration status of a first network over a first access. The UE ignores the registration result value because it does not accurately indicate the registration status of the first network over the first access.

The 5GS registration result IE can carry three different 5GS registration result values. If the 5GS registration result value = "3GPP access", then the UE should consider itself as being registered to 3GPP access only, and not registered to non-3GPP access. If the UE is in 5GMM-REGISTERED state over non-3GPP access and on the same PLMN as 3GPP access, then the UE enters state 5GMM-DEREGISTERED. If the 5GS registration result value = "non-3GPP access", then the UE should consider itself as being registered to non-3GPP access only, and not registered to 3GPP access. If the UE is in 5GMM-REGISTERED state over 3GPP access and on the same PLMN as non-3GPP access, then the UE enters state 5GMM-DEREGISTERED. If the 5GS registration result value = "3GPP access and non-3GPP access", then the UE should consider itself as being registered to both 3GPP access and being registered to non-3GPP access.

<FIG> illustrates a first embodiment of UE performing registration over a second access and receives a registration result value when a UE is not registered to a first access in accordance with one novel aspect. In step <NUM>, UE <NUM> determines that it is not registered to PLMN1 over a first access, e.g., 3GPP access <NUM>. In step <NUM>, UE <NUM> triggers a registration by sending a REGISTRATION REQUEST message to PLMN2 over a second access, e.g., non-3GPP access <NUM>. In step <NUM>, UE <NUM> receives a REGISTRATION ACCEPT message from PLMN2 over the second access type. The REGISTRATION ACCEPT message comprises a 5GS registration result IE, which carries a 5GS registration result value. In step <NUM>, UE <NUM> derives the 5GS registration result value = "3GPP access and non-3GPP access", indicating that the UE is registered to both networks over 3GPP access and over non-3GPP access. However, UE <NUM> knows that it is not registered to the first PLMN1. Since the 5GS registration result value is received over non-3GPP access, it may not accurately indicate the registration status for PLMN1 over 3GPP access. As a result, UE <NUM> ignores the received 5GS registration result value with respect to 3GPP access, and still considers itself NOT YET registered to the first PLMN1 over 3GPP access.

In <FIG>, UE <NUM> can access PLMN1 over 3GPP access <NUM> via a first AMF1, and UE <NUM> can access PLMN2 over non-3GPP access <NUM> via a second AMF2. If PLMN1 and PLMN2 belong to the same network, then AMF1 and AMF2 can be the same network entity. However, the UE <NUM> may deregister locally without notifying the AMF1 or AMF2. As a result, the AMF1 will provide wrong results. On the other hand, if PLMN1 and PLMN2 are two different networks, then AMF1 and AMF2 are two different entities. As a result, AMF1 may not know the current configuration and status of the UE with respect to non-3GPP access/PLMN2 that is stored in AMF2, and AMF2 may not know the current configuration and status of the UE with respect to 3GPP access/PLMN1 that is stored in AMF1. In the embodiment of <FIG>, UE <NUM> is not registered to PLMN1 over 3GPP access. AMF2 may not know the 5GS registration result over 3GPP access that is stored in AMF1. When UE <NUM> receives the 5GS registration result IE, and when the 5GS registration result value indicates that the UE is registered to both 3GPP access and non-3GPP access, UE <NUM> thus ignores the 5GS registration result value with respect to 3GPP access, and considers itself NOT YET registered to the first PLMN1 over 3GPP access. However, UE <NUM> considers itself registered to the second PLMN2 over non-3GPP access based on the 5GS registration result value.

<FIG> illustrates a second embodiment performing registration over a second access and receives a registration result value when a UE is registered to a first access in accordance with one novel aspect. In step <NUM>, UE <NUM> determines that it is registered to PLMN1 over a first access, e.g., 3GPP access <NUM>. In step <NUM>, UE <NUM> triggers a registration by sending a REGISTRATION REQUEST message to PLMN2 over a second access, e.g., non-3GPP access <NUM>. In step <NUM>, UE <NUM> receives a REGISTRATION ACCEPT message from PLMN2 over the second access type. The REGISTRATION ACCEPT message comprises a 5GS registration result IE, which carries a 5GS registration result value. In step <NUM>, UE <NUM> derives the 5GS registration result value = "non-3GPP access only", indicating that the UE is registered to PLMN2 over non-3GPP access only. However, UE <NUM> knows that it is registered to the first PLMN1. Since the 5GS registration result value is received over non-3GPP access, it may not accurately indicate the registration status for PLMN1 over 3GPP access. As a result, UE <NUM> ignores the received 5GS registration result value with respect to 3GPP access, and considers itself being registered to the first PLMN1 over 3GPP access. However, UE <NUM> considers itself registered to the second PLMN2 over non-3GPP access based on the 5GS registration result value.

<FIG> illustrates a third embodiment performing registration over a first access and receives a registration result value indicating UE is registered to a second access in accordance with one novel aspect. In step <NUM>, UE <NUM> triggers a registration procedure to PLMN1 over a first access, e.g., 3GPP access. In step <NUM>, UE <NUM> receives a REGISTRATION ACCEPT message from PLMN2 over the first access type, e.g., 3GPP access. The REGISTRATION ACCEPT message comprises a 5GS registration result IE, which carries a 5GS registration result value which indicating the UE <NUM> is registered to the second access, e.g., non-3GPP access. In step <NUM>, UE <NUM> derives the 5GS registration result value = "non-3GPP access only", indicating that the UE is registered to PLMN2 over non-3GPP access only. However, UE <NUM> knows that it triggers registration to the first PLMN1 over 3GPP, and did not trigger registration to the second PLMN2 over non-3GPP access. As a result, UE <NUM> ignores the received 5GS registration result value with respect to 3GPP access, and still considers itself being registered to the first PLMN1 over 3GPP access, or considers itself being registered to both the first PLMN over 3GPP access and the second PLMN over non-3GPP access.

<FIG> is a flow chart of a method of determining UE registration status for a UE that is registered to different PLMN networks over 3GPP and non-3GPP accesses in accordance with one novel aspect. In step <NUM>, a UE transmits a REGISTRATION REQUEST message to a second network over a second access type, wherein the UE is not registered to a first network via a first access type. In step <NUM>, the UE receives a REGISTRATION ACCEPT message over the second access type from the second network, wherein the message carries a 5GS registration result information element (IE). In step <NUM>, the UE derives a 5GS registration result value that indicates whether the UE is registered to the first network and the second network. In step <NUM>, the UE ignores the 5GS registration result value and considers the UE is not registered to the first network over the first access type.

Claim 1:
A method, comprising:
transmitting a REGISTRATION REQUEST message by a User Equipment, in the following also referred to as UE, (<NUM>, <NUM>, <NUM>) to a second network (<NUM>) over a second access type, wherein the UE is not registered to a first network (<NUM>) via a first access type, and wherein one of the first access type and the second access type is 3GPP access type (<NUM>), and the other one of the first access type and the second access type is non-3GPP access type (<NUM>);
receiving a REGISTRATION ACCEPT message over the second access type from the second network (<NUM>), wherein the message carries a 5GS registration result information element (IE); and
deriving a 5GS registration result value that is set to the first access type and the second access type indicating that the UE (<NUM>, <NUM>, <NUM>) is registered to both the first network (<NUM>) and the second network (<NUM>);
characterized by
considering the UE (<NUM>, <NUM>, <NUM>) is registered to the second network over the second access type and considering the UE (<NUM>, <NUM>, <NUM>) is not registered to the first network (<NUM>) over the first access type.