Techniques for handling legacy parameters and interworking with a new generation (6G) registration

Abstract

A UE can communicate with a first network operating in accordance with a first mobility management (MM) protocol and a second network operating in accordance with a second, different MM protocol. The UE performs a registration procedure with the first network. Upon successful completion of the registration procedure, the UE enters a first registration state for the first MM protocol, which causes the first network to provide normal service. The UE also enters a second registration state or a deregistered state for the second MM protocol. The second registration state indicates that the UE is registered but has no available cells on the second network. The UE resets a first attempt counter associated with the first network and resets a second attempt counter associated with the second network.

Description

[0001] Cross-references

[0002] This application claims priority to Indian Patent Application No. 202421069491, filed on September 13, 2024, entitled “Method for processing legacy parameters and interworking with next-generation (6G) registrations”, the entire contents of which are expressly incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to wireless communications, and more specifically, to techniques for coordinating registration and mobility management procedures for user equipment (UE) during interoperability between a next-generation network (e.g., a sixth-generation (6G) network) and one or more legacy networks. Background Technology

[0004] The content presented in this section is provided only as background information in relation to this disclosure and may not constitute prior art.

[0005] Wireless communication systems are widely deployed to provide a variety of telecommunications services, such as telephone, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0006] These multiple access technologies have been adopted by various telecommunications standards to provide a common protocol enabling different wireless devices to communicate at the city, national, regional, and even global levels. One example of a telecommunications standard is 5G New Radio (NR). 5G NR is part of the Continuous Evolution of Mobile Broadband program issued by the Third Generation Partnership Project (3GPP), designed to meet new requirements related to latency, reliability, security, scalability (e.g., the Internet of Things, IoT), and other requirements. Some aspects of 5G NR can be based on the 4G Long Term Evolution (LTE) standard. There is a need for further improvements to 5G NR technology in existing technologies. These improvements can also be applied to other multiple access technologies and telecommunications standards that employ such technologies. Summary of the Invention

[0007] The following is a simplified overview of one or more aspects to provide a basic understanding of those aspects. This overview is not an exhaustive summary of all anticipated aspects, and its purpose is neither to identify key or essential elements of all aspects nor to define 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 an introduction to the more detailed descriptions that follow.

[0008] In one aspect of this disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE (User Equipment). The UE is capable of communicating with a first network operating under a first mobility management (MM) protocol and a second network operating under a different second MM protocol. The UE performs a registration procedure with the first network. Upon successful completion of the registration procedure, the UE enters a first registration state for the first MM protocol, which enables the first network to provide normal service. The UE also enters a second registration state or a deregistration state for the second MM protocol. The second registration state indicates that the UE has registered but there are no available cells on the second network. The UE resets a first attempt counter associated with the first network and resets a second attempt counter associated with the second network.

[0009] In another aspect of this disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE (User Equipment). The UE performs an inter-system change from a first network to a second network, the first network and the second network operating according to different core network technologies. The UE determines whether an interoperability interface exists between a first core network associated with the first network and a second core network associated with the second network, enabling UE context transfer. Based on the determination of the existence of the interoperability interface, the UE selects either a first registration procedure or a second registration procedure. The first registration procedure establishes a new UE context in the second core network, and the second registration procedure utilizes an existing UE context transferred from the first core network. The UE executes the selected registration procedure to connect to the second network.

[0010] In another aspect of this disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE (User Equipment). The UE is capable of communicating with 6G, 5G, and 4G networks. In response to a failed registration attempt on any of the 6G, 5G, or 4G networks, the UE enters or maintains a 6GMobility Management (6GMM) deregistration state. The UE also enters or maintains a 5GMobility Management (5GMM) deregistration state. Furthermore, the UE also enters or maintains an Evolved Packet System Mobility Management (EMM) deregistration state. The UE performs these actions to synchronize its deregistration state across all supported network generations.

[0011] To achieve the foregoing and related objectives, the one or more aspects include the features that will be fully described below and specifically pointed out in the claims. Certain illustrative features of the one or more aspects are set forth in detail in the following description and the accompanying drawings. However, these features indicate only a few of the many ways in which the various aspects can be employed, and this description is intended to cover all such aspects and their equivalents. Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating an example of a wireless communication system and access network.

[0013] Figure 2 This is a schematic diagram illustrating communication between a base station and a UE in the access network.

[0014] Figure 3 An example logical architecture for a distributed access network is shown.

[0015] Figure 4An example physical architecture of a distributed access network is shown.

[0016] Figure 5 This is a schematic diagram illustrating a multi-generation interoperability architecture, in which the multi-mode UE 504 can communicate with networks of different generations.

[0017] Figure 6 This is a flowchart of a method for managing mobility state across multiple network generations.

[0018] Figure 7 This is a flowchart of a method for performing inter-system changes across networks.

[0019] Figure 8 This is a flowchart of a method for coordinating registration states across multiple network generations. Detailed Implementation

[0020] The specific embodiments described below with reference to the accompanying drawings are intended as descriptions of various configurations and are not intended to represent the only configuration in which the concepts described herein can be implemented. These specific embodiments contain detailed information intended to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can also be implemented without these detailed descriptions. In some cases, well-known structures and components are shown in block diagram form to avoid ambiguity in the description of these concepts.

[0021] Several aspects of a telecommunications system will now be presented with reference to various apparatuses and methods. These apparatuses and methods will be described in the following detailed embodiments and illustrated in the accompanying drawings by various blocks, components, circuits, programs, algorithms, etc. (collectively, “elements”). These elements can be implemented using electronic hardware, computer software, or any combination thereof. Whether these elements are implemented in hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0022] For example, a single element, any portion of an element, or any combination of elements can be implemented as a "processing system" including one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, system-on-a-chip (SoCs), baseband processors, field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described in this disclosure. One or more processors in a processing system can execute software. Software should be understood broadly as instructions, instruction sets, code, code segments, program code, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, programs, functions, etc., regardless of whether it is called software, firmware, middleware, microcode, hardware description languages, or other names.

[0023] Therefore, in one or more exemplary aspects, the functionality can be implemented in hardware, software, or any combination thereof. If implemented in software, such functionality can be stored as one or more instructions or code on or encoded in a computer-readable medium. Computer-readable media includes computer storage media. Storage media can be any available medium accessible to a computer. For example, and without limitation, such computer-readable media can include random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of computer-readable media of the types described above, or any other medium that can be used to store computer-accessible, computer-executable code in the form of instructions or data structures.

[0024] Figure 1This is a schematic diagram illustrating an example of a wireless communication system and access network 100. The wireless communication system (also known as a Wireless Wide Area Network (WWAN)) includes a base station 102, a user interface unit (UE) 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). The base station 102 may include macro cells (high-power cell base stations) and / or small cells (low-power cell base stations). Macro cells include base stations. Small cells include femtocells, picocells, and microcells.

[0025] Base station 102 configured for 4G LTE (collectively referred to as the Evolved UMTS Terrestrial Radio Access Network, E-UTRAN) can be interconnected with EPC 160 via backhaul link 132 (e.g., S1 interface). Base station 102 configured for 5G NR (collectively referred to as the Next Generation RAN, NG-RAN) can be interconnected with core network 190 via backhaul link 184. In addition to other functions, base station 102 may also perform one or more of the following functions: user data transmission, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and device tracking, RAN information management (RIM), paging, location, and transmission of alert messages. Base stations 102 may communicate directly or indirectly (e.g., via EPC 160 or core network 190) with each other via backhaul link 134 (e.g., X2 interface). Backhaul link 134 may be wired or wireless.

[0026] Base station 102 can wirelessly communicate with UE 104. Each base station 102 can provide communication coverage for a corresponding geographic coverage area 110. Geographic coverage areas 110 may overlap. For example, small cell 102' may have a coverage area 110' that overlaps with the coverage areas 110 of one or more macro base stations 102. A network that includes both small cells and macro cells can be called a heterogeneous network. A heterogeneous network may also include Home Evolved Node B (HeNB), which can provide services to a restricted group called a closed subscriber group (CSG). The communication link 120 between base station 102 and UE 104 may include uplink (UL) (also known as reverse link) transmission from UE 104 to base station 102, and / or downlink (DL) (also known as forward link) transmission from base station 102 to UE 104. Communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link may be carried out via one or more carriers. Base station 102 / UE 104 may use a spectrum with a bandwidth of up to 7 MHz per carrier (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.) in each direction, aggregated in a carrier aggregation manner to a total of up to Yx MHz (x component carriers) for transmission in each direction. Carriers may be adjacent or non-adjacent. Carrier allocation may be asymmetric for DL ​​and UL (e.g., more or fewer carriers may be allocated to DL than to UL). Component carriers may include one primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as the primary cell (PCell), and the secondary component carriers may be referred to as secondary cells (SCells).

[0027] Some UEs 104 can communicate with each other using device-to-device (D2D) communication links 158. D2D communication links 158 can use DL / UL WWAN spectrum. D2D communication links 158 can use one or more sidelink channels, such as the physical sidelink broadcast channel (PSBCH), physical sidelink discovery channel (PSDCH), physical sidelink shared channel (PSSCH), and physical sidelink control channel (PSCCH). D2D communication can be performed through various wireless D2D communication systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0028] The wireless communication system may also include a Wi-Fi access point (AP) 150, which communicates with a Wi-Fi station (STA) 152 via a communication link 154 in the 5 GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) before communication to determine whether the channel is available.

[0029] Cell 102' can operate in licensed and / or unlicensed spectrum. When operating in unlicensed spectrum, cell 102' can employ NR and use the same 5 GHz unlicensed spectrum as Wi-Fi AP 150. Employing NR in unlicensed spectrum can improve the coverage and / or increase the capacity of the access network.

[0030] Base station 102 (whether it is a small cell 102' or a large / small cell (e.g., a macro base station)) can include evolved Node B (eNB), gNodeB (gNB), or other types of base stations. Some base stations (e.g., gNB 180) can communicate with UE 104 in conventional sub-6 GHz spectrum, millimeter wave (mmW) frequencies, and / or near-mmW frequencies. When gNB 180 operates in mmW or near-mmW frequencies, gNB 180 can be referred to as an mmW base station. Extremely high frequency (EHF) is a part of the electromagnetic spectrum that includes radio frequency (RF). EHF ranges from 30 GHz to 300 GHz, with wavelengths between 1 mm and 10 mm. Radio waves in this band are referred to as millimeter waves. Near-mmW can extend down to frequencies of 3 GHz with wavelengths of 100 mm. Ultra-high frequency (SHF) bands lie between 3 GHz and 30 GHz, also known as centimeter waves. Communication using mmW / near-mmW RF bands (e.g., 3 GHz - 300 GHz) suffers from extremely high path loss and short-range characteristics. mmW base station 180 can utilize beamforming 182 with UE 104 to compensate for this extremely high path loss and short-range limitation.

[0031] Base station 180 can transmit beamforming signals to UE 104 in one or more transmit directions 108a. UE 104 can receive the beamforming signals from base station 180 in one or more receive directions 108b. UE 104 can also transmit beamforming signals to base station 180 in one or more transmit directions. Base station 180 can receive the beamforming signals from UE 104 in one or more receive directions. Base station 180 / UE 104 can perform beam training to determine the optimal receive and transmit directions for each. The transmit and receive directions of base station 180 can be the same or different. The transmit and receive directions of UE 104 can also be the same or different.

[0032] EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. MME 162 can communicate with the Home Subscriber Server (HSS) 174. MME 162 is the control node that handles signaling between UE 104 and EPC 160. Generally, MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are transmitted through the Serving Gateway 166, which is itself connected to the PDN Gateway 172. The PDN Gateway 172 provides UE IP address allocation and other functions. The PDN Gateway 172 and BM-SC 170 are connected to the IP Service 176. IP service 176 may include the Internet, intranet, IP Multimedia Subsystem (IMS), PS streaming media service, and / or other IP services. BM-SC 170 can provide MBMS user service provision and delivery functions. BM-SC170 can serve as an entry point for content provider MBMS transmission, can be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and can be used to schedule MBMS transmissions. MBMS gateway 168 can be used to distribute MBMS traffic to base station 102 belonging to a MulticastBroadcast Single Frequency Network (MBSFN) area for broadcast-specific services, and can be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0033] The core network 190 may include an Access and Mobility Management Function (AMF) 192, other AMFs 193, a Location Management Function (LMF) 198, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. The AMF 192 can communicate with the Unified Data Management (UDM) 196. The AMF 192 is the control node that handles signaling between the UE 104 and the core network 190. Generally, the SMF 194 provides QoS streaming and session management. All user IP packets are transmitted through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 connects to an IP service 197. The IP service 197 may include the Internet, an intranet, IMS, PS streaming services, and / or other IP services.

[0034] A base station may also be referred to as a gNB, Node B, eNB, access point, base transceiver station, wireless base station, wireless transceiver, transceiver function, basic service set (BSS), extended service set (ESS), transmit reception point (TRP), or other appropriate terms. Base station 102 provides UE 104 with access to EPC 160 or core network 190. Examples of UE 104 include cellular phones, smartphones, session initiation protocol (SIP) phones, laptops, personal digital assistants (PDAs), satellite radios, GPS devices, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablets, smart devices, wearable devices, vehicles, electricity meters, gas pumps, large or small kitchen appliances, healthcare devices, implantable devices, sensors / actuators, display devices, or any other device with similar functionality. Some UE 104 devices may be referred to as IoT devices (e.g., parking meters, gas pumps, toasters, vehicles, heart monitors, etc.). UE 104 may also be referred to as a station, mobile station, subscriber station, mobile unit, subscriber unit, radio unit, remote unit, mobile device, radio device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, radio terminal, remote terminal, mobile phone, user agent, mobile client, client, or other appropriate terms.

[0035] Although this disclosure may refer to 5G NR, it may also be applied to other similar fields, such as LTE, LTE-Advanced (LTE-A), Code Division Multiple Access (CDMA), Global System for Mobile communications (GSM), or other wireless / radio access technologies.

[0036] Figure 2This is a block diagram illustrating communication between base station 210 and UE 250 in the access network. In the DL, IP packets from EPC 160 can be provided to controller / processor 275. Controller / processor 275 implements Layer 3 and Layer 2 functions. Layer 3 includes the Radio Resource Control (RRC) layer, and Layer 2 includes the Packetdata Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, and Medium Access Control (MAC) layer. The controller / processor 275 provides the following functions: RRC layer functions related to system information broadcasting (e.g., Master Information Block (MIB), System Information Block (SIB)), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), cross-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functions related to header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functions related to upper-layer packet data units (PDU) transmission, error correction via Automatic Repeat reQuest (ARQ), concatenation, segmentation, and reassembly of RLC service data units (SDUs), resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and mapping between logical channels and transport channels, multiplexing MAC SDUs to transport blocks. MAC layer functions including blocks (TB), demultiplexing MAC SDU from TB, scheduling information reporting, error correction via Hybrid Automatic Repeat reQuest (HARQ), priority handling, and logical channel priority ordering.

[0037] The transmit (TX) processor 216 and receive (RX) processor 270 implement Layer 1 functions related to various signal processing functions. Layer 1 includes a physical (PHY) layer, which may include error detection on the transport channel, forward error correction (FEC) encoding / decoding on the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 216 processes the mapping to the signal constellation diagram based on various modulation schemes (e.g., Binary Phase-Shift Keying (BPSK), Quadrature Phase-Shift Keying (QPSK), M-Phase-Shift Keying (M-PSK), and M-Quadrature Amplitude Modulation (M-QAM)). The encoded, decoded, and modulated symbols can then be split into parallel streams. Each stream can then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., a pilot) in the time and / or frequency domains, and then combined using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time-domain OFDM symbol stream. This OFDM stream undergoes spatial pre-coding / decoding to generate multiple spatial streams. Channel estimation from channel estimator 274 can be used to determine the encoding / decoding and modulation schemes, as well as spatial processing. This channel estimation can be derived from a reference signal transmitted by UE 250 and / or channel condition feedback. Subsequently, each spatial stream can be provided to a different antenna 220 via a separate transmitter 218TX. Each transmitter 218TX can modulate an RF carrier with the corresponding spatial stream for transmission.

[0038] At UE 250, each receiver 254RX receives a signal via its corresponding antenna 252. Each receiver 254RX recovers the information modulated on the RF carrier and provides this information to the RX processor 256. The TX processor 268 and RX processor 256 implement Layer 1 functions related to various signal processing functions. The RX processor 256 can perform spatial processing on this information to recover any spatial streams destined for UE 250. If multiple spatial streams are destined for UE 250, the RX processor 256 can merge them into a single OFDM symbol stream. The RX processor 256 then uses a Fast Fourier Transform (FFT) to convert the OFDM symbol stream from the time domain to the frequency domain. This frequency domain signal includes the OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, along with the reference signal, are recovered and demodulated by determining the most probable signal constellation point transmitted by base station 210. These soft decisions can be based on channel estimates calculated by channel estimator 258. These soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted by base station 210 on the physical channel. These data and control signals are then provided to controller / processor 259, which implements Layer 3 and Layer 2 functions.

[0039] Controller / processor 259 may be associated with memory 260, which stores program code and data. Memory 260 may be referred to as a computer-readable medium. In UL, controller / processor 259 provides demultiplexing, packet reassembly, decryption, header decompression, and control signal processing for recovering IP packets from EPC 160 between transport and logical channels. Controller / processor 259 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operation.

[0040] Similar to the functions described above in conjunction with the DL transmission of base station 210, controller / processor 259 provides the following functions: RRC layer functions related to system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functions related to header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functions related to upper-layer PDU transmission, error correction via ARQ, RLC SDU concatenation, segmentation and reassembly, RLC data PDU resegmentation, and RLC data PDU reordering; and MAC layer functions related to mapping between logical channels and transport channels, multiplexing MAC SDUs to TB, demultiplexing MAC SDUs from TB, scheduling information reporting, error correction via HARQ, priority processing, and logical channel priority ordering.

[0041] The channel estimation derived by channel estimator 258 from the reference signal or feedback transmitted by base station 210 can be used by TX processor 268 to select appropriate encoding / decoding and modulation schemes and facilitate spatial processing. The spatial stream generated by TX processor 268 can be provided to different antennas 252 via individual transmitters 254TX. Each transmitter 254TX can modulate an RF carrier with a corresponding spatial stream for transmission. The processing of UL transmission at base station 210 is similar to that described above in conjunction with the receiver function of UE 250. Each receiver 218RX receives signals through its corresponding antenna 220. Each receiver 218RX recovers the information modulated on the RF carrier and provides this information to RX processor 270.

[0042] Controller / processor 275 may be associated with memory 276, which stores program code and data. Memory 276 may be referred to as computer-readable medium. In the UL, controller / processor 275 provides demultiplexing, packet reassembly, decryption, header decompression, and control signal processing for recovering IP packets from UE 250 between transport and logical channels. IP packets from controller / processor 275 may be provided to EPC 160. Controller / processor 275 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operation.

[0043] NR can refer to a radio configured to operate under a new air interface (e.g., an air interface not based on Orthogonal Frequency Divisional Multiple Access (OFDMA)) or a fixed transport layer (e.g., non-IP). NR can use OFDM with a cyclic prefix (CP) on both uplink and downlink and may include support for half-duplex operation using time division duplexing (TDD). NR can include mission-critical applications for enhanced mobile broadband (eMBB) services with wide bandwidths (e.g., above 80 MHz), millimeter wave (mmW) services with high carrier frequencies (e.g., 60 GHz), massive machine-type communications (mMTC) that are incompatible with existing MTC technologies, and / or ultra-reliable low latency communications (URLLC) services.

[0044] It can support a single component carrier bandwidth of 100 MHz. In one example, an NR resource block (RB) can span 12 subcarriers with a subcarrier bandwidth of 60 kHz and a duration of 0.25 ms, or a subcarrier bandwidth of 30 kHz and a duration of 0.5 ms (similarly, a 15 kHz sub-carrier spacing (SCS) results in a 50 MHz bandwidth and a duration of 1 ms). Each radio frame can consist of 10 subframes of 10 ms each (10, 20, 40, or 80 NR slots). Each slot can indicate the link direction (i.e., DL or UL) used for data transmission, and the link direction of each slot can be dynamically switched. Each slot can include DL / UL data and DL / UL control data. The UL and DL slots of NR can be described below. Figure 5 and Figure 6 As described in the detailed description.

[0045] NR RAN can include a central unit (CU) and a distributed unit (DU). NR base stations (e.g., gNB, 5G Node B, Node B, TRP, AP) can correspond to one or more base stations. NR cells can be configured as access cells (ACells) or data-only cells (DCells). For example, the RAN (e.g., central unit or distributed unit) can configure such cells. DCells can be cells used for carrier aggregation or dual connectivity and may not be used for initial access, cell selection / reselection, or handover. In some cases, DCells may not transmit synchronization signals (SS), and in other cases, DCells may transmit SS. NR base stations can transmit downlink signals indicating the cell type to the UE. Based on this cell type indication, the UE can communicate with the NR base station. For example, the UE can determine which NR base stations should be considered during cell selection, access, handover, and / or measurement based on the indicated cell type.

[0046] Figure 3An example logical architecture of a distributed RAN 300 according to various aspects of this disclosure is illustrated. A 5G access node 306 may include an access node controller (ANC) 302. This ANC may be the CU of the distributed RAN. Backhaul interfaces to the next-generation core network (NG-CN) 304 may terminate at this ANC. Backhaul interfaces to adjacent next-generation access nodes (NG-AN) 310 may also terminate at this ANC. This ANC may include one or more TRPs 308 (which may also be referred to as BS, NR BS, NodeB, 5G NB, AP, or other terms). As mentioned above, the term TRP can be used interchangeably with the term "cell".

[0047] TRP 308 may be a DU. Such TRPs may connect to one ANC (ANC 302) or multiple ANCs (not shown). For example, for RAN sharing, radio as a service (RaaS), and service-specific ANC deployments, the TRP may connect to multiple ANCs. A TRP may include one or more antenna ports. Such TRPs may be configured to provide services to the UE individually (e.g., dynamically selected) or jointly (e.g., jointly transmitted).

[0048] The local architecture of the distributed RAN 300 can be used to illustrate the definition of fronthaul. This architecture can be defined as a fronthaul solution that supports different deployment types. For example, the architecture can be based on transport network capabilities (e.g., bandwidth, latency, and / or jitter). The architecture can share features and / or components with LTE. Depending on various aspects, the NG-AN 310 can support dual connectivity with NR. The NG-AN can share common fronthaul for both LTE and NR.

[0049] This architecture enables collaboration between TRPs 308 and within each TRP. For example, collaboration can be pre-configured within a TRP and / or between multiple TRPs via ANC 302. Depending on various aspects, inter-TRP interfaces may be unnecessary or nonexistent.

[0050] Depending on various factors, the distributed RAN 300 architecture allows for dynamic configuration of split logical functions. The PDCP, RLC, and MAC protocols can be adaptively configured at the ANC or TRP.

[0051] Figure 4An example physical architecture of a distributed RAN 400 according to various aspects of this disclosure is shown. A centralized core network unit (C-CU) 402 can host core network functions. This C-CU can be centrally deployed. C-CU functions can be offloaded (e.g., to advanced wireless services (AWS)) to handle peak capacity. A centralized RAN unit (C-RU) 404 can host one or more ANC functions. This C-RU can also host core network functions locally. This C-RU can be deployed in a distributed manner. This C-RU can be located closer to the network edge. A DU 406 can host one or more TRPs. This DU can be located at the network edge and has RF functionality.

[0052] Figure 5 Figure 500 illustrates an example of a wireless communication system demonstrating the interoperability challenges and solutions for multi-mode UEs operating across 4G, 5G, and 6G networks. UE 504 is a multi-mode device capable of establishing connections with multiple network generations simultaneously or sequentially. UE 504 can connect to 6G base station 502, 5G base station 512, and 4G base station 522, each providing access to its respective core network via a dedicated backhaul link.

[0053] The 6G network architecture includes a 6G base station 502, which provides access to the 6G Radio Access Network (6G-RAN), which is connected to the 6G core network 540 via a backhaul link 542. The 6G core network 540 can be implemented as a standalone 6G core network, an evolved 5G core network supporting 6G services, or a network connected to the IMT-2030 network framework. The 6G base station 502 communicates with the UE 504 via a wireless communication link 506, enabling the UE 504 to register and receive services using the 6G-RAN or 6G NAS protocols when operating in 6G mode.

[0054] The 5G network includes a 5G base station 512, implemented as a gNB, connected to the 5G core network 550 via a backhaul link 552. The 5G base station 512 provides NG-RAN access to the UE 504 via a wireless communication link 514, enabling the UE 504 to operate in N1 mode to obtain 5G services. Similarly, the 4G network includes a 4G base station 522, implemented as an eNB, connected to the EPC 560 via a backhaul link 562. The 4G base station 522 communicates with the UE 504 via a wireless communication link 524, enabling the UE 504 to operate in S1 mode to obtain 4G services.

[0055] This system architecture demonstrates three key interoperability interfaces that determine UE registration and mobility procedures. The 6G-5G interoperability interface 570 connects the 6G core network 540 and the 5G core network 550. This interface can be implemented as an Nxx interface or a similar mechanism, enabling context transfer between the 6G and 5G core networks. When this interface is present, UE 504 can perform mobility registration procedures when switching between 5G and 6G networks, achieving efficient handover without requiring complete re-authentication or context reconstruction. This interface facilitates the exchange of UE context information, including security credentials, UE identity parameters (such as a Globally Unique Temporary Identifier (GUTI), and session information.

[0056] The 6G-4G interoperability interface 580 can selectively connect the 6G core network 540 and the EPC 560. Conceptually similar to the N26 interface used between 5G and 4G networks, this interface determines whether the UE 504 can perform a mobility-based procedure or must perform an initial registration procedure when moving between 4G and 6G systems. The presence of this interface allows the 6G core network 540 to obtain the UE context from the EPC 560 during system transitions from S1 mode to 6G mode, enabling the UE 504 to perform a mobility registration procedure in 6G. Conversely, when the UE 504 moves from 6G mode to S1 mode with this interface present, it can perform a Tracking Area Update (TAU) procedure instead of a full attach procedure. However, in many deployment scenarios, this interface is expected to be absent, requiring the UE 504 to perform an initial registration when moving from 4G to 6G and a full attach procedure when moving from 6G to 4G.

[0057] The 5G-4G interoperability interface 590 connects the 5G core network 550 and the EPC 560, representing the existing N26 interface for interoperability between 5G and 4G systems. This existing interface provides a reference model for the 6G interoperability mechanism proposed in this disclosure and demonstrates the benefits of core network interoperability for seamless mobility management.

[0058] In the first scenario, when UE 504 operates in this multi-generation environment, its behavior in coordinating registration states across different mobility management (MM) protocols is undefined. UE 504 may need to maintain three different MM states: 6GMM (6G Mobility Management) for 6G operation, 5GMM (5G Mobility Management) for 5G operation, and EMM (EPS Mobility Management) for 4G operation. Without explicit coordination rules, UE 504 may encounter inconsistent states, such as being registered in one network generation but unregistered in another, leading to handover failures, service interruptions, or inability to perform inter-system changes.

[0059] See Figure 5 In the second approach, a set of rules is defined to regulate the behavior of UE 504 in environments with 6G, 5G, and 4G networks, thereby resolving undefined coordination issues between different network generations. A fundamental rule establishes a unified deregistration state. If UE 504 fails to register successfully on the 6G network, for example, after a failed registration attempt, it enters the 6GMM-deregistration state. To maintain consistency in state across its different radio access capabilities, UE 504 also enters the 5GMM-deregistration state for its 5G mobility management and the EMM-deregistration state for its 4G mobility management. This synchronization of deregistration states across mobility management layers provides a consistent benchmark and prevents ambiguity where UE 504 might be considered registered on an older network while simultaneously being deregistered on the 6G network.

[0060] For various operational scenarios, a coordination method between the 6GMM and 5GMM states of UE 504 is defined. When UE 504 operates in 6G mode and successfully registers with the 6G core network 540, it enters the 6GMM-Registered state with a normal service sub-state. Simultaneously, UE 504 sets its 5G state to the 5GMM-Registered state with a "No Available Cells" sub-state. This primary / standby model maintains the registration context of the 5G network, preparing for potential inter-system changes from UE 504 to the 5G base station 512. After this successful registration, UE 504 also resets its 6G registration attempt counter and 5G registration attempt counter. Resetting these counters allows UE 504 to attempt new registrations on networks where it may have previously reached its maximum attempt limit.

[0061] Symmetrically, if UE 504 successfully completes the registration procedure with the 5G core network 550 in N1 mode, it will enter the 5GMM-Registered state for normal service and the 6GMM-Registered state with the "No Available Cells" sub-state. UE 504 will also reset both registration attempt counters. For example, this action is beneficial if UE 504 had previously exhausted its 6G registration attempts before moving to 5G, as the reset allows it to attempt registration again upon subsequent inter-system changes back to the 6G network.

[0062] Furthermore, if UE 504 can operate in dual-mode, for example, connecting to the 6G-RAN via 6G base station 502 and simultaneously connecting to the NG-RAN via 5G base station 512, successful registration of this dual-mode operation will bring both the 6GMM and 5GMM states of UE 504 into normal service status. In this case, UE 504 will also reset the 6G and 5G registration attempt counters.

[0063] The procedure for inter-system changes between 5G and 6G networks is also defined, the specific procedure depending on the presence of the 6G-5G interoperability interface 570. When UE 504 performs an inter-system change from N1 mode to 6G mode, and the interface 570 exists to allow communication between the 6G core network 540 and the 5G core network 550, UE 504 performs a mobility registration procedure. This procedure is used because the 6G core network 540 can obtain the necessary UE context, such as GUTI or security context, from the 5G core network 550 via the interface 570. However, if the 6G-5G interoperability interface 570 does not exist, the core networks cannot exchange context. In this case, UE 504 performs an initial registration procedure in the 6G network. Regardless of the procedure used, after successfully changing to the 6G network, UE 504 enters the 6GMM-Registered state for normal service and the 5GMM-Registered state with the "No Available Cells" sub-state.

[0064] Furthermore, the coordination between the 6GMM state and EMM state of UE 504 standardizes the behavior of the UE when operating across 6G and 4G networks. This coordination resolves various scenarios regarding whether there is direct communication between the 6G core network 540 and the EPC 560 via the 6G-4G interoperability interface 580.

[0065] When UE 504 operates in S1 mode and successfully completes the attach procedure or tracking area update procedure with EPC 560 via 4G base station 522, UE 504 enters the EMM-Registered state with a normal service sub-state to maintain its active connection to the 4G network. For its 6G capability management, UE 504 has two state configuration options. The primary option is to enter the 6GMM-Deregistered state with the "No Available Cells" sub-state, which is particularly suitable when there is no 6G-4G interoperability interface 580 between the 6G core network 540 and EPC 560. Alternatively, in deployments where some form of coordination between networks is expected, UE 504 can enter the 6GMM-Registered state with the "No Available Cells" sub-state. Choosing the Deregistered state as the primary option prevents synchronization conflicts that might occur if UE 504 attempts to maintain a registration context in both networks without an interface exchange context. After the 4G procedure is successfully completed, the UE 504 will reset its 6G registration attempt counter and 4G attach attempt counter, thereby enabling it to make new registration attempts on any network without being limited by previous failed attempts.

[0066] Conversely, when UE 504 operates in 6G mode and successfully completes the registration procedure with the 6G core network 540 via the 6G base station 502, UE 504 enters the 6GMM-Registered state with a normal service sub-state for its active 6G connection. For its 4G capabilities, UE 504 primarily enters the EMM-Deregistered state, but can alternatively enter the EMM-Registered state with a "No Available Cells" sub-state. The deregistered state is preferred in the EMM, reflecting the expectation that the 6G-4G interoperability interface 580 will not exist. If this interface does not exist, and UE 504 maintains the Registered state in the EMM, and subsequently performs an inter-system change from 6G to 4G, it will attempt the TAU procedure. Since the interface 580 does not exist, the EPC 560 cannot obtain the necessary UE context (such as security keys or temporary identifiers) from the 6G core network 540, therefore the TAU procedure will fail. By setting the EMM to a deregistered state, UE 504 prepares to perform a full attach procedure when moving to the 4G network, which establishes a new context without transferring information from the 6G core network 540. Upon successful 6G registration, UE 504 resets its 6G registration attempt counter and 4G attach attempt counter to prevent registration lockout and enable future registration attempts on both networks.

[0067] Furthermore, the procedures for inter-system changes between the 6G network and the 4G network are defined based on the presence of the 6G-4G interoperability interface 580. This interface, which can be implemented as an N26-like interface or a similar interoperability mechanism, determines whether the UE 504 can perform efficient mobility-based procedures during network transitions or must perform a full initial connection procedure. Interface 580 facilitates the exchange of UE context information between the 6G core network 540 and the EPC 560, including security parameters, temporary identifiers (e.g., GUTI), and session information.

[0068] When a UE 504, which simultaneously supports 4G and 6G capabilities, performs an inter-system change from S1 mode to 6G mode in the absence of the 6G-4G interoperability interface 580, there is no interoperability mechanism between the EPC 560 and the 6G core network 540, making context passing impossible. Therefore, the UE 504 must perform an initial registration procedure in the 6G network through the 6G base station 502 and the wireless communication link 506. This initial registration establishes a completely new context within the 6G core network 540, without relying on any existing information from the 4G network. After successful initial registration, the UE 504 enters the 6GMM-Registered state with a normal service sub-state, thereby activating its 6G connectivity. For its 4G mobility management, the UE 504 transitions to the EMM-Deregistered state with the "No Available Cells" sub-state, or maintains the EMM-Registered state with the "No Available Cells" sub-state. The choice between these EMM states depends on the specific deployment scenario and whether any residual 4G context should be maintained.

[0069] In contrast, when the 6G-4G interoperability interface 580 is present and provides interoperability between the 4G core network and the 6G core network, the same system transition from S1 mode to 6G mode will follow a more efficient path. The presence of interface 580 allows the 6G core network 540 to directly obtain the UE context from the EPC 560. Therefore, UE 504 performs a mobility registration procedure in the 6G network, rather than an initial registration. This mobility registration procedure reuses existing security contexts and identifiers obtained via interface 580, thereby reducing signaling overhead and connection establishment time. After successful mobility registration, UE 504 enters a 6GMM-registered state with normal service for its active 6G connection. This EMM state transitions to an EMM-deregistered state with "no available cells" or an EMM-registered state with "no available cells," thus providing flexibility for 4G mobility management based on operator policies and network configuration.

[0070] Conversely, when UE 504 performs an inter-system change from 6G mode to S1 mode in the absence of the 6G-4G interoperability interface 580, EPC 560 cannot obtain any UE context from the 6G core network 540. This lack of context delivery necessitates that UE 504 perform a complete attach procedure within the 4G network via the 4G base station 522 and the wireless communication link 524. This attach procedure establishes a completely new session within EPC 560, including authentication, security settings, and bearer establishment. Upon successful completion of the attach procedure, UE 504 enters the EMM-registered state with a normal service sub-state, thus enabling the 4G connection. Simultaneously, the 6G service is effectively suspended, and UE 504 transitions its 6GMM state to the 6GMM-deregistered state with a "no available cells" sub-state, thereby preventing any 6G-related operations while UE 504 is operating in the 4G network.

[0071] When the 6G-4G interoperability interface 580 provides interoperability during system transitions from 6G mode to S1 mode, the EPC 560 can obtain the necessary UE context from the 6G core network 540 via the interface 580. This context transfer capability enables the UE 504 to perform a TAU procedure in the 4G network, which is significantly more efficient than a full attach procedure. The TAU procedure updates the UE's location and reactivates the existing security context without requiring a full re-authentication. After the TAU procedure is successfully completed, the UE 504 enters the EMM-registered state with normal service for active 4G operations. The 6GMM state transitions to the 6GMM-deregistered state with "no available cells," thereby inactivating the 6G capability while retaining the possibility of future conversion back to the 6G network.

[0072] The procedures differentiated based on interface availability reflect actual deployment considerations. Without the 6G-4G interoperability interface 580, these networks would operate independently, requiring the establishment of a complete context during each transition. While this approach is more resource-intensive, it avoids the complexity of maintaining synchronization between non-communicating core networks. When the interface 580 is present, these networks can exchange context information, enabling seamless transitions that maintain session continuity and reduce service interruption time. UE504 adjusts its behavior accordingly, performing lightweight mobility procedures when interoperability is available, or performing full initialization procedures when network communication is unavailable, thereby maintaining reliable connectivity in heterogeneous network environments encompassing 4G, 5G, and 6G technologies.

[0073] Figure 6Flowchart 600 illustrates a method for managing mobility states across multiple network generations. This method can be performed by a UE (e.g., UE 504) capable of communicating with a first network operating according to a first MM protocol and a second network operating according to a different second MM protocol.

[0074] In operation 602, the UE performs a registration procedure with the first network. In operation 604, after the registration procedure is successfully completed, the UE enters a first registration state for the first MM protocol. This first registration state enables the first network to provide normal service. In operation 606, the UE enters a second registration state or a deregistration state for the second MM protocol. The second registration state indicates that the UE has registered but there are no available cells on the second network. In operation 608, the UE resets the first attempt counter associated with the first network. In operation 610, the UE resets the second attempt counter associated with the second network.

[0075] In some implementations, the first network is a 6G network operating according to the 6GMM protocol, and the second network is a 5G network operating according to the 5GMM protocol. In some implementations, the first network is a 6G network operating according to the 6GMM protocol, and the second network is a 4G network operating according to the EMM protocol. In some implementations, the first network is a 5G network operating according to the 5GMM protocol, and the second network is a 6G network operating according to the 6GMM protocol.

[0076] In some implementations, the UE can also communicate with a third network operating according to a third MM protocol. After the registration procedure with the first network is successfully completed, the UE enters a third state for the third MM protocol. This third state is either a registration state with no available cells or a deregistration state. The UE also resets the third attempt counter associated with the third network.

[0077] In some implementations, the first network is a 6G network, the second network is a 5G network, and the third network is a 4G network. When there is no interoperability interface between the 6G network and the 4G network, the third state is the EMM deregistration state.

[0078] In some implementations, the UE is capable of performing dual-mode operation, supporting simultaneous connection to both the first network and the second network. After successful registration for this dual-mode operation, the UE enters a first registration state with normal service for the first MM protocol and a second registration state with normal service for the second MM protocol. The UE resets the first attempt counter and the second attempt counter.

[0079] Figure 7Flowchart 700 illustrates a method for a UE to perform an inter-system change from a first network to a second network. This method can be performed by a UE (e.g., UE 504).

[0080] In operation 702, the UE determines whether an interoperability interface exists between a first core network associated with the first network and a second core network associated with the second network, enabling UE context transfer. The first network and the second network operate using different core network technologies. In operation 704, based on the determination of whether the interoperability interface exists, the UE selects either a first registration procedure or a second registration procedure. The first registration procedure establishes a new UE context in the second core network, and the second registration procedure utilizes an existing UE context transferred from the first core network. In operation 706, the UE executes the selected registration procedure to connect to the second network.

[0081] In some implementations, the first network is a 5G network with a 5G core network, and the second network is a 6G network with a 6G core network. The first registration procedure is an initial registration procedure, and the second registration procedure is a mobility registration procedure.

[0082] In some implementations, the first network is a 4G network with EPC, and the second network is a 6G network with a 6G core network. When the interoperability interface does not exist, the first registration procedure is an initial registration procedure. When the interoperability interface exists, the second registration procedure is a mobility registration procedure.

[0083] In some implementations, the first network is a 6G network with a 6G core network, and the second network is a 4G network with an EPC. When the interoperability interface does not exist, the first registration procedure is an attach procedure. When the interoperability interface exists, the second registration procedure is a TAU procedure.

[0084] In some implementations, the UE context transmitted through the interoperability interface includes at least one of a security context, a GUTI, or session information.

[0085] In some implementations, after the selected registration procedure is successfully completed, the UE enters a registration state with normal service for the mobility management protocol of the second network. The UE enters a registration state with no available cells or a deregistration state for the mobility management protocol of the first network. The UE resets the attempt counters for the first network and the second network.

[0086] In some implementations, after the attach procedure or TAU procedure is successfully completed, the UE enters the EMM registered state with normal service. The UE then enters the 6GMM deregister state with no available cells.

[0087] Figure 8 Flowchart 800 illustrates a method for coordinating registration states across multiple network generations. This method can be executed by a UE (e.g., UE 504) capable of communicating with 6G, 5G, and 4G networks.

[0088] In operation 802, in response to a failed registration attempt on any of the 6G network, 5G network, or 4G network, the UE enters or maintains a 6GMM deregistration state. In operation 804, the UE enters or maintains a 5GMM deregistration state. In operation 806, the UE enters or maintains an EMM deregistration state. These operations enable the UE to enter the deregistration state synchronously across all supported network generations.

[0089] In some implementations, upon successfully registering with the 6G network after a failed registration attempt, the UE transitions from the 6GMM deregistered state to the 6GMM registered state with normal service. The UE also transitions from the 5GMM deregistered state to the 5GMM registered state with no available cells. Depending on whether there is an interoperability interface between the 6G network and the 4G network, the UE may maintain the EMM deregistered state or transition to the EMM registered state with no available cells.

[0090] In some implementations, upon successful attachment or tracking area update to the 4G network after a failed registration attempt, the UE transitions from the EMM deregistration state to the EMM registered state with normal service. The UE maintains the 6GMM deregistration state with no available cells. The UE maintains the 5GMM deregistration state or transitions to the 5GMM registered state with no available cells.

[0091] In some implementations, the 6G network includes at least one of the following: 6G-RAN; NG-RAN connected to the IMT-2030 network; an evolved 5G core network; or a standalone 6G core network.

[0092] In some implementations, the UE connects to the 6G network using at least one of the following: the 6G-RAN protocol; or the 6G NAS protocol when operating in 6G mode.

[0093] In some implementations, the UE resets the 6G attempt counter, 5G attempt counter, and 4G attempt counter after any successful registration or attachment procedure on the 6G network, the 5G network, or the 4G network.

[0094] Figure 5 The UE 504 shown, and the execution Figures 6 to 8 The UE of the method can adopt the same as Figure 2The UE 250 shown is implemented with similar hardware components, adapted to support multi-generation network connectivity, including 6G capabilities. Specifically, UE 504 includes multiple receivers 254RX and transmitters 254TX coupled to their respective antennas 252 to enable communication with 6G base station 502, 5G base station 512, and 4G base station 522 via wireless communication links 506, 514, and 524, respectively. RX processor 256 and TX processor 268 implement Layer 1 functions for processing signals according to different radio access technologies, including 6G-RAN, NG-RAN (5G), and E-UTRAN (4G) protocols. Controller / processor 259, combined with memory 260 storing program code and data, implements higher-level functions including the 6GMM, 5GMM, and EMM protocols disclosed herein. Controller / processor 259 executes coordination logic for managing registration status across different network generations, maintaining independent attempt counters for each network type, and determining the appropriate registration procedure based on the presence or absence of an inter-core network interoperability interface.

[0095] The memory 260 of UE 504 stores not only program code for implementing multi-generation mobility management procedures, but also maintains various state information and counters as described in this disclosure, including 6GMM states (registered / deregistered and their respective sub-states), 5GMM states, EMM states, and their associated registration attempt counters. The controller / processor 259 utilizes this stored information to make decisions related to inter-system changes, such as determining whether an initial registration procedure or a mobility registration procedure should be executed during network transitions, and synchronizing the deregistration state across all supported network generations when registration fails on any network. Therefore, this hardware architecture enables UE 504 to operate in 6G mode, N1 mode (5G), S1 mode (4G), or dual-mode configurations, and the controller / processor 259 manages complex state transitions, ensuring consistent behavior in heterogeneous network environments as defined in the disclosed methods for handling legacy parameters and interoperating with 6G registration.

[0096] It should be understood that the specific order or hierarchy of blocks in the disclosed program / flowchart is merely illustrative. For design considerations, it should be understood that the specific order or hierarchy of blocks in this program / flowchart can be rearranged. Furthermore, some blocks can be merged or omitted. The appended method claims present the elements of each block in an exemplary order and are not intended to limit the scope to the specific order or hierarchy presented.

[0097] The foregoing description is intended to enable any person skilled in the art to implement the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Therefore, the claims are not intended to limit them to the aspects shown herein, but should be given the full scope consistent with the text of the claims, wherein, unless expressly stated otherwise, reference to an element in the singular does not mean “only one,” but rather “one or more.” The term “exemplary” as used herein means “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” should not necessarily be construed as superior to or more advantageous than other aspects. Unless expressly stated otherwise, the term “some” means 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 multiple A, multiple B, or multiple 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" can be only A, only B, only C, A and B, A and C, B and C, or A, B, and C, wherein any such combination may include one or more members of A, B, or C. All content known or likely to be known hereafter by one of ordinary skill in the art that is structurally and functionally equivalent to elements of all aspects described throughout this disclosure is expressly incorporated herein by reference and is intended to be covered by the claims. Furthermore, nothing disclosed herein is intended to be made public, whether or not it is expressly stated in the claims. Terms such as "module," "mechanism," "element," and "device" may not replace the word "means." Therefore, unless the element is expressly stated using the phrase "means for," no claim element should be interpreted as means plus function.

Claims

1. A method performed by a user equipment, the user equipment being capable of communicating with a first network operating according to a first mobility management protocol and a second network operating according to a different second mobility management protocol, the method comprising: Perform the registration process with the first network; as well as After the registration process is completed successfully: The first mobility management protocol enters a first registration state, which enables the first network to provide normal services; Regarding the second mobility management protocol entering a second registration state or a deregistration state, the second registration state indicates that the user equipment has registered but there are no available cells on the second network; Reset the first attempt counter associated with the first network; and Reset the second attempt counter associated with the second network.

2. The method of claim 1, wherein the first network is a sixth-generation network operating in accordance with the sixth-generation mobility management protocol, and the second network is a fifth-generation network operating in accordance with the fifth-generation mobility management protocol.

3. The method of claim 1, wherein the first network is a sixth-generation network operating in accordance with the sixth-generation mobility management protocol, and the second network is a fourth-generation network operating in accordance with the evolved packet system mobility management protocol.

4. The method of claim 1, wherein the first network is a fifth-generation network operating in accordance with the fifth-generation mobility management protocol, and the second network is a sixth-generation network operating in accordance with the sixth-generation mobility management protocol.

5. The method of claim 1, wherein the user equipment is further capable of communicating with a third network operating in accordance with a third mobility management protocol, the method further comprising: After the registration process with the first network is successfully completed: The third mobility management protocol enters a third state, which is either a registration state with no available cells or a deregistration state; and Reset the third attempt counter associated with the third network.

6. The method of claim 5, wherein: This first network is a sixth-generation network; This second network is a fifth-generation network; This third network is a fourth-generation network; as well as When there is no interoperability interface between the sixth-generation network and the fourth-generation network, the third state is the Evolved Packet System Mobility Management Deregistration State.

7. The method of claim 1, wherein the user equipment is capable of performing dual-mode operation supporting simultaneous connection to the first network and the second network, the method further comprising: After successful registration for this dual-mode operation: The first mobility management protocol is used to enter the first registration state with normal service; The second mobility management protocol is used to enter the second registration state with normal service; as well as Reset the first attempt counter and the second attempt counter.

8. A method for enabling a user equipment to perform an inter-system change from a first network to a second network, the first network and the second network operating according to different core network technologies, the method comprising: Determine whether there is an interoperable interface between the first core network associated with the first network and the second core network associated with the second network that enables the transfer of user equipment context; Based on the determination of whether the interoperability interface exists, one of the first registration program or the second registration program is selected, wherein the first registration program establishes a new user equipment context in the second core network, and the second registration program utilizes the existing user equipment context passed from the first core network. as well as Perform the selected registration procedure to connect to the second network.

9. The method of claim 8, wherein: This first network is a fifth-generation network with a fifth-generation core network; This second network is a sixth-generation network with a sixth-generation core network; This first registration procedure is the initial registration procedure; and The second registration procedure is a mobility registration procedure.

10. The method of claim 8, wherein: This first network is a fourth-generation network with an evolved packet core; This second network is a sixth-generation network with a sixth-generation core network; When the interoperability interface does not exist, the first registration program is the initial registration program; as well as When the interoperability interface exists, the second registration procedure is a mobility registration procedure.

11. The method of claim 8, wherein: This first network is a sixth-generation network with a sixth-generation core network; The second network is a fourth-generation network with an evolved packet core; When the interoperability interface does not exist, the first registration procedure is an attachment procedure; as well as When the interoperability interface exists, the second registration procedure is the tracking area update procedure.

12. The method of claim 8, wherein the user equipment context transmitted through the interconnection interface includes at least one of the following: Security context; Globally unique temporary identifier; or Session information.

13. The method of claim 8, further comprising: After the selected registration process is successfully completed: The mobility management protocol for this second network enters a registered state with normal service; The mobility management protocol of this first network enters a registration state or a deregistration state when there are no available cells. as well as Reset the attempt counters for the first network and the second network.

14. The method of claim 11, further comprising: After the attachment procedure or the tracking area update procedure is successfully completed: Entering the registered state of Evolved Packet System Mobility Management with normal service; as well as Enter the sixth-generation mobility management registration state where there are no available cells.

15. A method performed by a user equipment capable of communicating with a sixth-generation network, a fifth-generation network, and a fourth-generation network, the method comprising: In response to a failed registration attempt on any of the sixth-generation network, the fifth-generation network, or the fourth-generation network: Enter or maintain a deregistered state under the sixth-generation mobility management system; Entering or maintaining a deregistered state under fifth-generation mobility management; and To enter or maintain the Evolved Packet System Mobility Management deregistration state, This allows the user equipment to synchronously enter the deregistration state across all supported network generations.

16. The method of claim 15, further comprising: The response was a successful registration with the sixth-generation network after the registration attempt failed: The process transitions from the deregistered state of the sixth-generation mobility management system to the registered state of the sixth-generation mobility management system with normal service. The state transitions from the deregistered state of the fifth-generation mobility management system to the registered state of the fifth-generation mobility management system when there are no available cells; or Maintain the EPC Mobility Management (EMM) deregistered state, or transition to an EPM Mobility Management (EMM) registered state where no cells are available.

17. The method of claim 15, further comprising: The response is a successful attachment to the fourth-generation network or a successful tracking area update after the registration attempt fails: The transition from the deregistered state of Evolved Packet System Mobility Management (EPM) to the registered state of EPM with normal service; and Maintain the unregistered state of the sixth-generation mobility management system, or switch to the registered state of the sixth-generation mobility management system when there are no available cells.

18. The method of claim 15, wherein the sixth-generation network comprises at least one of the following: 6th generation wireless access network; Next-generation radio access networks connected to the International Mobile Communications-2030 network; The evolving fifth-generation core network; or An independent sixth-generation core network.

19. The method of claim 15, further comprising: In response to any successful registration or attachment procedure on any of the sixth-generation network, the fifth-generation network, or the fourth-generation network, reset the sixth-generation attempt counter, the fifth-generation attempt counter, or the fourth-generation attempt counter.

20. An apparatus for wireless communication, the apparatus being a user equipment, comprising: Memory; as well as At least one processor, coupled to the memory and configured to perform the following operations: The registration process is performed with the first network operating in accordance with the first mobility management protocol; as well as In response to the successful completion of the registration process: The first mobility management protocol enters a first registration state, which enables the first network to provide normal services; Regarding the second mobility management protocol entering a second registration state or a deregistration state, wherein the second mobility management protocol is different from the first mobility management protocol and is associated with a second network, and wherein the second registration state indicates that the user equipment has registered but there are no available cells on the second network; Reset the first attempt counter associated with the first network; and Reset the second attempt counter associated with the second network.

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