State transitions during disaster roaming wait

Abstract

According to one aspect of the present disclosure, a method, a computer readable medium, and an apparatus are provided. The device may be a user device. The user equipment selects a network for disaster roaming. The user equipment starts a timer with a randomly generated value within a disaster roaming waiting range. When the user equipment is in a logout state, the user equipment enters a 5G mobility management-logout state when the timer runs, and attempts to be in a registration (5GMM-DEREGISTERED.ATTEMPTNG-REGISTRATION) state. When the user equipment is in a registration state, the user equipment enters a 5G mobility management-registration state when the timer runs, and a registration update (5GMM-REGISTERED.ATTEMPTNG-REGISTRATION-UPDATE) state is attempted. While the timer is running, the user equipment avoids starting any 5G mobility hypervisor in addition to emergency services.

Description

[0001] Cross-referencing

[0002] This application claims priority to Indian Patent Application Serial No. 202321045847, entitled “Method for defining state transition during disaster roaming wait,” filed on 7 July 2023, the entire contents of which are expressly incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to communication systems, and more specifically, to techniques for managing 5G mobility management (5GMM) state transitions while user equipment is waiting for disaster roaming. Background Technology

[0004] The statements in this section provide only 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 to support communication with multiple users by sharing available system resources. Examples of these 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 in 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 ongoing evolution of mobile broadband driven by the Third Generation Partnership Project (3GPP) 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 may be based on the 4G Long Term Evolution (LTE) standard. Further improvements to 5G NR technology are needed. These improvements may also apply to other multiple access technologies and the telecommunications standards that adopt them. Summary of the Invention

[0007] The following provides a simplified summary of one or more aspects to provide a basic understanding of them. This summary is not a comprehensive overview of all aspects considered, nor is it intended to identify key or important 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 a foreshadowing of 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 user equipment (UE). The UE selects a network for disaster roaming. While within the disaster roaming waiting range, the UE starts a timer with a randomly generated value. When the UE is in a deregistered state, it enters a 5G Mobility Management (5GMM) deregister state while the timer is running. When the UE is in a registered state, it enters a 5G Mobility Management (5GMM) register state while the timer is running. The UE avoids initiating any 5G Mobility Management procedures, except for emergency services, while the timer is running.

[0009] In another aspect of this disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a user equipment (UE). The UE determines that a disaster situation has ended. The UE selects a network to return from disaster roaming. The UE starts a timer with a randomly generated value within the disaster return waiting range. While the timer is running, the UE enters a first 5G mobility management state. When the UE is in a deregistration state, the first 5G mobility management state is a 5G mobility management deregistration state attempting registration. When the UE is in a registration state, the first 5G mobility management state is a 5G mobility management registration state attempting registration update. While the timer is running, the UE avoids initiating any 5G mobility management procedures, except for emergency services.

[0010] To achieve the foregoing and related objectives, one or more aspects include the following features, which will be described in detail and specifically pointed out in the claims. The following description and drawings list in detail certain illustrative features of one or more aspects. However, these features only illustrate a portion of several ways in which the principles of the various aspects may be adopted, and this description is intended to include all such aspects and their equivalents. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of an example wireless communication system and access network.

[0012] Figure 2 It is a schematic diagram illustrating the communication between a base station and user equipment in the access network.

[0013] Figure 3 This demonstrates an example logical architecture for a distributed access network.

[0014] Figure 4 This demonstrates an example physical architecture for a distributed access network.

[0015] Figure 5 This is a schematic diagram illustrating an example of a downlink-centric time slot.

[0016] Figure 6 It is a schematic diagram illustrating an example of an uplink-centric timeslot.

[0017] Figure 7 This is a schematic diagram illustrating communication between user equipment, a regular public land mobile network (PLMN), and a disaster relief public land mobile network.

[0018] Figure 8 This is a schematic diagram illustrating the 5G mobility management state transition of a user device.

[0019] Figure 9It is a flowchart illustrating how to manage disaster roaming procedures in emergency situations.

[0020] Figure 10 It is a flowchart illustrating how to manage disaster roaming procedures when a disaster situation ends. Detailed Implementation

[0021] The detailed description below, taken with reference to the accompanying drawings, is intended to describe various configurations and is not intended to represent the only configuration in which the concepts described herein can be practiced. The detailed description includes specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. In some cases, well-known structures and components are shown in block diagram form to avoid obscuring these concepts.

[0022] Several aspects of a telecommunications system will now be introduced with reference to various devices and methods. These devices and methods will be described in detail below and illustrated in the accompanying drawings by various modules, components, circuits, processes, algorithms, etc. (collectively, “elements”). These elements can be implemented using electronic hardware, computer software, or any combination of both. Whether these elements are implemented as hardware or software depends on the specific application and design constraints imposed on the overall system.

[0023] For example, an element, any part of an element, or any combination of elements can be implemented as a “processing system” containing 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, systems on a chip (SoCs), baseband processors, field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other hardware suitable for performing 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, application programs, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description languages, or others.

[0024] Therefore, in one or more example aspects, the described functionality can be implemented in hardware, software, or any combination of both. If implemented in software, these functions can be stored or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media include computer storage media. Storage media can be any available medium that is accessible to a computer. For example, and not limited to, such computer-readable media can include random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), optical disc 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-executable code in the form of instructions or data structures and is accessible to a computer.

[0025] 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 base station 102, user equipment 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). Base station 102 may include macro cells (high-power cellular base stations) and / or small cells (low-power cellular base stations). Macro cells include base stations. Small cells include femtocells, picocells, and microcells.

[0026] Base station 102 configured as 4G LTE (collectively referred to as the Evolved Universal Terrestrial Radio Access Network, E-UTRAN) can interface with EPC 160 via backhaul link 132 (e.g., SI interface). Base station 102 configured as 5G NR (collectively referred to as Next Generation RAN, NG-RAN) can interface with core network 190 via backhaul link 184. In addition to other functions, base station 102 may perform one or more of the following functions: transmission of user data, encryption and decryption of radio channels, 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), user and device tracking, RAN information management (RIM), paging, location, and warning message delivery. Base station 102 may communicate with each other directly or indirectly (e.g., via EPC160 or core network 190) via backhaul link 134 (e.g., X2 interface). Backhaul link 134 may be wired or wireless.

[0027] Base station 102 can wirelessly communicate with user equipment 104. Each base station 102 can provide communication coverage for a corresponding geographic coverage area 110. Overlapping geographic coverage areas 110 may exist. 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 containing small cells and macro cells may be referred to as a heterogeneous network. Heterogeneous networks may also include Home Evolved Node Bs (HeNBs), which can provide services to a restricted group called a closed subscriber group (CSG). The communication link 120 between base station 102 and user equipment 104 may include uplink (UL) (also known as reverse link) transmission from user equipment 104 to base station 102 and / or downlink (DL) (also known as forward link) transmission from base station 102 to user equipment 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 / user equipment 104 may allocate each carrier with a bandwidth of up to 7 MHz (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.) in carrier aggregation, using 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 asymmetrical in terms of DL and UL (e.g., DL may be allocated more or fewer carriers than 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).

[0028] Some user equipment 104 can communicate with each other using device-to-device (D2D) communication links 158. D2D communication links 158 can use DL / UL wireless wide area network (WWAN) spectrum. D2D communication links 158 can use one or more sidelink channels, such as 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.

[0029] The wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with Wi-Fi stations (STAs) 152 via a communication link 154 in the 5 GHz unlicensed spectrum. When communicating in the unlicensed spectrum, STAs 152 / AP 150 may perform a clear channel assessment (CCA) before communication to determine if the channel is available.

[0030] 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 enhance the coverage and / or increase the capacity of the access network.

[0031] Base station 102, whether a small cell 102' or a large-area (e.g., a macro base station), may include evolved Node B (eNB), gNodeB (gNB), or other types of base stations. Some base stations, such as gNB 180, can communicate with user equipment 104 in conventional sub-6 GHz spectrum, millimeter wave (mmW) frequencies, and / or near-millimeter wave frequencies. When gNB 180 operates in millimeter wave or near-millimeter wave frequencies, gNB 180 may be referred to as a millimeter wave base station. Extremely high frequency (EHF) is a portion of the radio frequency (RF) spectrum in the electromagnetic spectrum. EHF ranges from 30 GHz to 300 GHz, with wavelengths between 1 mm and 10 mm. Radio waves in this band may be referred to as millimeter waves. Near-millimeter waves can extend down to frequencies of 3 GHz with wavelengths of 100 mm. The ultra-high frequency (SHF) band is between 3 GHz and 30 GHz, also known as centimeter waves. Communication using millimeter-wave / near-millimeter-wave radio frequency bands (e.g., 3 GHz - 300 GHz) suffers from extremely high path loss and short range. Millimeter-wave base station 180 can utilize beamforming 182 to communicate with user equipment 104 to compensate for the extremely high path loss and short range.

[0032] Base station 180 can transmit beamforming signals to user equipment 104 in one or more transmit directions 108a. User equipment 104 can receive beamforming signals from base station 180 in one or more receive directions 108b. User equipment 104 can also transmit beamforming signals to base station 180 in one or more transmit directions. Base station 180 can receive beamforming signals from user equipment 104 in one or more receive directions. Base station 180 / user equipment 104 can perform beam training to determine the optimal receive and transmit directions for base station 180 / user equipment 104. The transmit and receive directions of base station 180 may be the same or different. The transmit and receive directions of user equipment 104 may be the same or different.

[0033] 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. Typically, MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are transmitted through Serving Gateway 166, which is itself connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation and other functions. PDN Gateway 172 and BM-SC 170 are connected to IP Service 176. IP service 176 may include the Internet, intranet, IP Multimedia Subsystem (IMS), PS streaming service, and / or other IP services. BM-SC 170 can provide MBMS user service provisioning and delivery functions. BM-SC 170 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 located in a Multicast Broadcast Single Frequency Network (MBSFN) area, which broadcasts specific services, and may be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0034] 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. Typically, the SMF 194 provides QoS streaming and session management. All user Internet Protocol (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, an IP Multimedia Subsystem (IMS), PS streaming services, and / or other IP services.

[0035] A base station may also be referred to as a gNB, Node B, evolved 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 suitable 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 broadcasting, GPS, 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, medical devices, implants, sensors / actuators, displays, or any other similarly functional device. Some UE 104 devices may be referred to as Internet of Things (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, user station, mobile unit, user unit, radio unit, remote unit, mobile device, radio device, wireless communication device, remote device, mobile user station, access terminal, mobile terminal, radio terminal, remote terminal, mobile phone, user agent, mobile client, client, or other suitable terms.

[0036] Although this disclosure may refer to 5G New Radio (NR), it may also apply 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 / wireless access technologies.

[0037] Figure 2This is a block diagram illustrating communication between base station 210 and user equipment 250 in the access network. In the downlink, 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 packet data convergence protocol (PDCP) layer, radio link control (RLC) layer, and medium access control (MAC) layer. The controller / processor 275 provides RRC layer functions related to system information (e.g., MIBs, SIBs) broadcasting, RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-Radio Access Technology (RAT) mobility, and measurement configuration for user equipment measurement reports; 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 unit (PDU) transmission, error correction via ARQ, RLC service data unit (SDU) connection, 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 of MAC SDUs to transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via HARQ, priority handling, and logical channel priority.

[0038] The transmit (TX) processor 216 and receive (RX) processor 270 implement Layer 1 functions related to various signal processing functions. Layer 1, including the physical (PHY) layer, may include error detection on the transport channel, forward error correction (FEC) encoding / decoding of 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 signal constellation mapping according to 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 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 generate a physical channel carrying a stream of time-domain OFDM symbols. The OFDM streams are spatially precoded to generate multiple spatial streams. Channel estimates from channel estimator 274 can be used to determine coding and modulation schemes, as well as spatial processing. The channel estimates can be derived from the reference signal and / or channel condition feedback transmitted by user equipment 250. Each spatial stream can then be provided to different antennas 220 via a separate transmitter 218TX. Each transmitter 218TX can modulate an RF carrier to transmit the corresponding spatial stream.

[0039] At user equipment 250, each receiver 254RX receives a signal via its corresponding antenna 252. Each receiver 254RX recovers the information modulated onto the RF carrier and provides the information to the receive (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 the information to recover any spatial stream targeted at user equipment 250. If multiple spatial streams are targeted at user equipment 250, they can be combined by the RX processor 256 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. The frequency domain signal comprises individual OFDM symbol streams for each subcarrier of the OFDM signal. The symbols and reference signals on each subcarrier are recovered and demodulated by determining the most probable signal constellation points transmitted by base station 210. These soft decisions can be based on channel estimates calculated by channel estimator 258. The soft decision is then decoded and deinterleaved to recover the data and control signals originally transmitted by base station 210 on the physical channel. The data and control signals are then provided to controller / processor 259, which implements Layer 3 and Layer 2 functions.

[0040] Controller / processor 259 may be associated with memory 260, which stores program code and data. Memory 260 may be referred to as computer-readable medium. In the uplink, controller / processor 259 provides demultiplexing, packet reassembly, decryption, header decompression, and control signal processing between the transport and logical channels to recover IP packets from EPC 160. Controller / processor 259 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operation.

[0041] Similar to the functions described in the downlink transmission of base station 210, controller / processor 259 provides RRC layer functions related to system information (e.g., MIB, SIBs) 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 connection, 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 of MAC SDUs to TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via HARQ, priority processing, and logical channel priority.

[0042] The channel estimate derived by channel estimator 258 from the reference signal or feedback transmitted from base station 210 can be used by transmission processor 268 to select appropriate coding and modulation schemes and facilitate spatial processing. The spatial stream generated by transmission processor 268 can be provided to different antennas 252 via individual transmitters 254TX. Each transmitter 254TX can modulate an RF carrier and transmit it with the corresponding spatial stream. Uplink transmission is processed in base station 210 in a manner similar to that described in the receiving function of user equipment 250. Each receiver 218RX receives the signal through its corresponding antenna 220. Each receiver 218RX recovers the information modulated onto the RF carrier and provides the information to receiver processor 270.

[0043] Controller / processor 275 may be associated with memory 276, which stores program code and data. Memory 276 may be referred to as a computer-readable medium. In the uplink, controller / processor 275 provides demultiplexing, packet reassembly, decryption, header decompression, and control signal processing between transport and logical channels to recover IP packets from user equipment 250. IP packets from controller / processor 275 may be provided to evolved packet core (EPC) 160. Controller / processor 275 is also responsible for error detection using acknowledgment (ACK) and / or denial (NACK) protocols to support Hybrid Automatic Repeat Request (HARQ) operation.

[0044] New Radio (NR) can refer to a radio operating under a new air interface (e.g., a non-Orthogonal Frequency Divisional Multiple Access (OFDMA) air interface) or a fixed transport layer (e.g., a non-Internet Protocol (IP) configuration). NR can use Orthogonal Frequency Division Multiplexing (OFDM) with a cyclic prefix (CP) in both uplink and downlink, and may include supporting half-duplex operation using time division duplexing (TDD). NR may include Enhanced Mobile Broadband (eMBB) services targeting wide bandwidth (e.g., above 80 MHz), millimeter wave (mmW) services targeting high carrier frequencies (e.g., 60 GHz), massive machine-type communication (mMTC) services targeting backward-incompatible MTC technologies, and / or mission-critical services targeting ultra-reliable low-latency communication (URLLC) services.

[0045] 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 bandwidth of 30 kHz and a duration of 0.5 ms (similarly, a 15 kHz subcarrier spacing represents a 50 MHz bandwidth over a 1 ms duration). Each radio frame can consist of 10 subframes (10, 20, 40, or 80 NR slots) with a length of 10 ms. Each slot can indicate the link direction of data transmission (i.e., downlink or uplink), and the link direction of each slot can be dynamically switched. Each slot can include downlink / uplink data and downlink / uplink control data. NR uplink and downlink slots can be configured as follows: Figure 5 and Figure 6 As described in more detail in the text.

[0046] A Radio Access Network (RAN) may include a central unit (CU) and distributed units (DUs). NR base stations (e.g., gNB, 5G Node B, Node B, Transmission Reception Point (TRP), Access Point (AP)) may 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 cells. DCells may 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); in others, they may transmit SS. NR base stations may transmit downlink signals to user equipment (UEs) to indicate the cell type. Based on the cell type indication, UEs can communicate with NR base stations. For example, UEs can determine which NR base stations to consider for cell selection, access, handover, and / or measurement based on the indicated cell type.

[0047] Figure 3An example logical architecture of a distributed RAN 300 according to aspects of this disclosure is shown. A 5G Access Node (5GAN) 306 may include an Access Node Controller (ANC) 302. The ANC may be the central unit of the distributed RAN. The backhaul interface to the next-generation core network (NG-CN) 304 may terminate at the ANC. The backhaul interface to neighboring next-generation access nodes (NG-ANs) 310 may terminate at the ANC. The ANC may include one or more TRPs 308 (also referred to as base stations, NR base stations, Node B, 5G NB, AP, or other terms). As mentioned above, TRP can be used interchangeably with "cell".

[0048] TRP 308 can be a distributed unit (DU). A TRP can 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, a TRP can connect to multiple ANCs. A TRP can include one or more antenna ports. A TRP can be configured to provide traffic services to user equipment individually (e.g., dynamically selected) or jointly (e.g., jointly transmitted).

[0049] The local architecture of the distributed RAN 300 can be used to illustrate the fronthaul definition. The architecture can be defined to support fronthaul solutions across 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 the aspect, the Next Generation Access Node (NG-AN) 310 can support dual connectivity with NR. The NG-AN can share a common fronthaul for both LTE and NR.

[0050] This architecture enables collaboration between TRPs 308. For example, collaboration can be established within a TRP and / or across TRPs via ANC 302. Depending on certain aspects, inter-TRP interfaces may not be required or may not exist.

[0051] Depending on certain aspects, the architecture of a distributed RAN 300 may allow for dynamic configuration of segmentation logic functions. PDCP, RLC, and MAC protocols can be adaptively placed on the ANC or TRP.

[0052] Figure 4An example physical architecture of a distributed RAN 400 according to one aspect of this disclosure is shown. A centralized core network unit (C-CU) 402 can carry core network functions. The C-CU can be centrally deployed. C-CU functions can be offloaded (e.g., to advanced wireless service (AWS)) to handle peak capacity. A centralized RAN unit (C-RU) 404 can carry one or more ANC functions. Optionally, the C-RU can carry core network functions locally. The C-RU can be distributed. The C-RU can be closer to the network edge. A distributed unit (DU) 406 can carry one or more TRPs. The DU can be located at the network edge with radio frequency (RF) capabilities.

[0053] Figure 5 This is a diagram 500 showing an example of a downlink-centric timeslot. The downlink-centric timeslot may include a control section 502. Control section 502 may exist in the initial or beginning portion of the downlink-centric timeslot. Control section 502 may include various scheduling and / or control information corresponding to different portions of the downlink-centric timeslot. In some configurations, control section 502 may be a Physical Downlink Control Channel (PDCCH), such as... Figure 5 As shown. The downlink-centric time slot may also include a downlink data portion 504. The downlink data portion 504 may sometimes be referred to as the payload of the downlink-centric time slot. The downlink data portion 504 may include communication resources for transmitting downlink data from a scheduling entity (e.g., a user equipment (UE) or a base station (BS)) to a subordinate entity (e.g., a user equipment (UE)). In some configurations, the downlink data portion 504 may be a Physical Downlink Shared Channel (PDSCH).

[0054] The downlink-centric time slot may also include a common uplink portion 506. The common uplink portion 506 may sometimes be referred to as an uplink burst, a common uplink burst, and / or other suitable terms. The common uplink portion 506 may include feedback information corresponding to other portions of the downlink-centric time slot. For example, the common uplink portion 506 may include feedback information corresponding to the control portion 502. Examples of non-limiting feedback information may include an acknowledgment signal (ACK), a negative acknowledgment (NACK) signal, a hybrid automatic repeat request (HARQ) indicator, and / or other suitable types of information. The common uplink portion 506 may include additional or alternative information, such as information related to random access channel (RACH) procedures, scheduling requests (SR), and other suitable types of information.

[0055] like Figure 5 As shown, the end of the downlink data portion 504 may be time-separated from the start of the common uplink portion 506. This time separation may sometimes be referred to as a gap, guard period, guard interval, and / or other appropriate terms. This separation provides time for the handover from downlink communication (e.g., reception operations of a subordinate entity (e.g., a user equipment (UE)) to uplink communication (e.g., transmission operations of a subordinate entity (e.g., a user equipment (UE))). Those skilled in the art will understand that the above is merely one example of a downlink-centric timeslot, and alternative structures with similar characteristics may exist without departing from the aspects described herein.

[0056] Figure 6 This is a diagram 600 showing an example of an uplink-centric timeslot. The uplink-centric timeslot may include a control section 602. The control section 602 may be present in the initial or beginning portion of the uplink-centric timeslot. Figure 6 The control section 602 in the reference can be similar to the one described above. Figure 5The control portion 502 is described. The uplink-centric time slot may also include an uplink data portion 604. The uplink data portion 604 may sometimes be referred to as the payload of the uplink-centric time slot. The uplink portion may refer to communication resources used for transmitting uplink data from a subordinate entity (e.g., a user equipment (UE)) to a scheduling entity (e.g., a user equipment (UE) or a base station (BS)). In some configurations, the control portion 602 may be the Physical Downlink Control Channel (PDCCH).

[0057] like Figure 6 As shown, the end of control section 602 may be time-separated from the start of uplink data section 604. This time separation may sometimes be referred to as a gap, protection period, protection interval, and / or other appropriate terms. This separation provides time for switching from downlink communication (e.g., receive operations of a scheduling entity) to uplink communication (e.g., transmit operations of a scheduling entity). The uplink-centric time slot may also include a common uplink section 606. Figure 6 The common uplink portion 606 in the reference can be similar to the one described above. Figure 5 The common uplink portion 506 is described. Common uplink portion 606 may additionally or alternatively include information related to channel quality indicators (CQI), sounding reference signals (SRS), and other suitable types of information. Those skilled in the art will understand that the above is merely one example of an uplink-centric timeslot, and alternative structures with similar characteristics may exist without departing from the aspects described herein.

[0058] In some cases, two or more dependent entities (e.g., user equipment) may use sidechain signaling to communicate. Practical applications of such sidechain communication may include public safety, proximity services, user equipment-to-network relay, vehicle-to-vehicle (V2V) communication, Internet of Things (IoE) communication, Internet of Things (IoT) communication, mission-critical meshes, and / or various other applicable applications. Typically, sidechain signaling may refer to signaling communication from one dependent entity (e.g., user equipment 1) to another dependent entity (e.g., user equipment 2) without relaying the communication through a scheduling entity (e.g., user equipment or base station), even if the scheduling entity may be used for scheduling and / or control purposes. In some examples, sidechain signaling may use licensed spectrum for communication (unlike wireless LANs that typically use unlicensed spectrum).

[0059] Figure 7Figure 700 illustrates communication between User Equipment 704, a Regular Public Land Mobile Network 710, and a Disaster Use Public Land Mobile Network 720. Under normal operation, User Equipment 704 connects to Base Station 702 and initially registers with the Regular Public Land Mobile Network 710, which can be the User Equipment's Home Public Land Mobile Network (HomePLMN, HPLMN) or Visited Public Land Mobile Network (Visited PLMN, VPLMN). The Regular Public Land Mobile Network 710 provides standard cellular service to User Equipment 704 under normal conditions via Base Station 702. The Disaster Use Public Land Mobile Network 720 operates Base Station 712, which is adjacent to Base Station 702. Under normal conditions, the Disaster Use Public Land Mobile Network 720 may be a disabled Public Land Mobile Network for User Equipment 704. User Equipment 704 may have the same structure and components as User Equipment 250. Base Stations 702 and 712 may have the same structure and components as Base Station 210.

[0060] Disaster roaming is a feature specified in the 3GPP standard that allows users to access other mobile networks (e.g., using the public land mobile network 720 during a disaster or emergency) even if their home network (e.g., the regular public land mobile network 710) is unavailable. It enables users to access voice and data services on other networks when their home network is paralyzed due to a disaster or emergency. Information about disaster roaming may be broadcast by the regular public land mobile network 710 in a System Information Block (SIB).

[0061] In the event of a disaster, such as a tsunami or earthquake, user equipment 704 may lose coverage of its regular public terrestrial mobile network 710. To maintain communication service during such events, the Minimization of Service Interruption (MINT) function comes into play. Both user equipment 704 and the network need to support MINT to achieve this function.

[0062] MINT is a feature designed to provide uninterrupted service to User Equipment (UE) in disaster scenarios. When a disaster affects a UE's registered public land mobile network (RPLMN), MINT enables the UE to obtain service from another RPLMN that provides disaster roaming services. This allows the user to maintain communication even when their home network is compromised.

[0063] MINT facilitates disaster roaming by enabling user equipment to select and register with a disaster-use public terrestrial mobile network, providing continuous service availability during emergencies. MINT implements wait timers, such as disaster roaming wait ranges and disaster return wait ranges, to prevent network congestion during disasters. These timers introduce random delays before user equipment attempts to register with a disaster-use public terrestrial mobile network or returns to its home network after the disaster, mitigating potential overload on the relevant networks.

[0064] The network (e.g., a conventional public terrestrial mobile network 710) notifies the user equipment 704 of disaster roaming configurations through various mechanisms. For example, these configurations may be provided to the user equipment via 3GPP or non-3GPP access during a registration procedure or user equipment configuration update procedure.

[0065] The network provides basic disaster roaming parameters to user equipment, which may store these parameters in its non-volatile memory. The parameters include:

[0066] - Disaster Roaming Enabled Indicator: This indicates whether disaster roaming is enabled for the user's device.

[0067] - Applicability of the "List of Public Land Mobile Networks for Disaster Situations" provided by accessing public land mobile networks: This indicates whether a user equipment should utilize the list of public land mobile networks for disaster use provided by accessing public land mobile networks.

[0068] - List of public terrestrial mobile networks for disaster situations: This list specifies the public terrestrial mobile networks that user equipment may consider for disaster roaming.

[0069] - Disaster Roaming Waiting Range: This range defines the possible values ​​of a random timer that a user device starts before attempting to register to a public terrestrial mobile network during a disaster.

[0070] - Disaster Return Waiting Range: This range defines the possible values ​​of a random timer that a user device starts before attempting to register with its home network after a disaster has ended.

[0071] The Home Public Land Mobile Network (HPLMN) can activate disaster roaming for user equipment 704 by setting the "Disaster Roaming Enabled in User Equipment" indicator using the user equipment parameter update procedure. This procedure allows the Home Public Land Mobile Network to dynamically update the disaster roaming configuration on the user equipment.

[0072] During the registration process, the network may provide or update a "list of public terrestrial mobile networks for disaster situations" to the user equipment. This list may be included in the registration request or the user equipment configuration update message. Therefore, the user equipment has up-to-date information about available public terrestrial mobile networks for disaster situations.

[0073] The network (e.g., a regular public land mobile network 710 and / or a disaster-use public land mobile network 720) notifies the user equipment 704 of the current disaster situation through various means. In particular, the network may broadcast disaster-related information in a system information block. The system information block contains basic parameters and indications related to disaster roaming. For example, the system information block may also include a list of one or more public land mobile networks that provide disaster roaming services.

[0074] The network may update the system information block to reflect the current disaster status and then broadcast it to all user equipment within the cell coverage area. Upon receiving the updated system information block, user equipment 704 can extract information about the disaster situation and the availability of disaster roaming services on other public land mobile networks (such as public land mobile network 720 used during a disaster). The user equipment checks whether its registered public land mobile network or equivalent public land mobile network is included in the list. If it is, the user equipment confirms the disaster situation in its home network and continues the disaster roaming procedure.

[0075] In addition to the System Information Block (SIB), the User Equipment (UE) may detect a loss of service or severe service degradation on its regular Public Land Mobile Network (PLMN) 710, which may indicate that the network infrastructure has been affected by a disaster scenario. Furthermore, the UE 704 can be programmed to recognize specific Non-Access Stratum (NAS) signaling messages used by the network to indicate a disaster situation. These messages may instruct the UE to initiate a disaster roaming procedure or activate a pre-configured emergency communication mode.

[0076] Upon detecting a disaster, UE 704 determines whether to initiate disaster roaming based on information provided by the network, UE capabilities, and current network conditions. Disaster roaming will only be attempted when necessary and appropriate.

[0077] UE 704 first checks for any available and permitted public land mobile networks. Permitted public land mobile networks are those that the UE is allowed to access under subscription and roaming agreements. If suitable public land mobile networks are available, the UE will prioritize registering with these networks before considering disaster roaming.

[0078] UE 704 verifies that it is not currently in the 5G Mobility Management-Registered (5G-REGISTERED) and Connection Management-Connected (CM-CONNECTED) states on a non-3GPP access network connected to the 5G Core Network (5GC). This prevents unnecessary disaster roaming when alternative connection options are available.

[0079] UE 704 confirms that it cannot obtain service on non-3GPP access networks via the evolved Packet Data Gateway (ePDG). Disaster roaming is used as a last resort when other non-3GPP access options are not feasible.

[0080] UE 704 must support disaster roaming, and the disaster roaming enable indication must be set to "Disaster roaming enabled in UE". This indication is configured by the Home Public Land Mobile Network (HPLMN) to indicate that the UE is permitted and able to perform disaster roaming when needed.

[0081] In addition, there must be a public terrestrial mobile network (PTN) without disaster conditions willing to accept disaster-entry roamers from a PTN experiencing a disaster. UE 704 has a potential network that can be connected for disaster roaming.

[0082] Typically, UE 704 first checks if any permitted public land mobile networks are available. Permitted public land mobile networks are those not blocked by any network or user and compatible with the UE's capabilities and subscription. If no permitted public land mobile networks are available, UE 704 meets the disaster roaming criteria and searches neighboring cells broadcasting disaster-related information about disabled public land mobile networks. Based on the received information, the UE uses a priority method to select a public land mobile network for disaster roaming.

[0083] UE 704 prioritizes disabled public land mobile networks (PLCs) that broadcast disaster information related to a disaster situation as determined by the mobile station (MS) (e.g., regular public land mobile network 710). This allows the UE to potentially access a network that is normally prohibited but provides disaster roaming service in an emergency. If no suitable PLC is found in the previous step, the UE may consider other disabled PLCs, although this is less likely to succeed because these PLCs may not be prepared to accept disaster roamers.

[0084] When UE 704 selects a public land mobile network for disaster roaming, such as public land mobile network 720, it starts a timer with a randomly generated value within the disaster roaming waiting range. This timer is designed to prevent network congestion by distributing multiple UEs simultaneously seeking registration attempts for disaster roaming services. When this timer expires, UE 704 should perform the disaster roaming service registration procedure.

[0085] Similarly, when UE 704 determines that the disaster situation has ended and a public land mobile network selection procedure should be performed to return to its regular public land mobile network 710, it starts another timer with a randomly generated value within the disaster return waiting period. This timer is used to prevent congestion on the regular public land mobile network 710 by dispersing the UE's registration attempts. When this timer expires, UE 704 should perform the registration procedure on the selected regular public land mobile network 710.

[0086] Figure 8 This is a diagram illustrating the 5G mobility management state transitions of UE 704. During disaster roaming, UE 704 undergoes various 5G mobility management state transitions. Initially, UE 704 is in the 5G mobility management-registered state 802 with the regular public terrestrial mobile network 710.

[0087] After a disaster affecting the regular public terrestrial mobile network 710 is detected, the 5G mobility management status of UE 704 can be either 5G mobility management - registered status or 5G mobility management - deregistered status, depending on the specific circumstances.

[0088] If UE 704 is still able to maintain registration with the regular public terrestrial mobile network 710 in a disaster scenario, it will remain in the 5G Mobility Management-Registered state. This may occur if the disaster scenario does not completely disrupt the ability of the regular public terrestrial mobile network 710 to provide services to UE 704. Therefore, UE 704 leaves state 802 and enters the 5G Mobility Management-Registered state .PLMN Search (5GMM-REGISTERED.PLMN-SEARCH) state 804 to search for an alternative public terrestrial mobile network, such as public terrestrial mobile network 720 used in a disaster.

[0089] On the other hand, if a disaster severely impacts the regular public terrestrial mobile network 710 and UE 704 is unable to maintain its registration, UE 704 will transition to the 5G Mobility Management - Deregistration state. This may occur when the regular public terrestrial mobile network 710 becomes completely unavailable or when the network explicitly deregisters UE 704 due to the disaster. Therefore, UE 704 leaves state 802 and enters the 5G Mobility Management Registration state 834 to search for an alternative public terrestrial mobile network, such as public terrestrial mobile network 720 used in the disaster.

[0090] Once UE 704 selects disaster use of public land mobile network 720 for disaster roaming in state 804 or state 834, it starts a timer with a randomly generated value within the disaster roaming wait range. This randomization helps prevent network congestion by distributing registration attempts from multiple UEs.

[0091] During the timer's operating window, the 5G mobility management state of UE 704 should be explicitly defined. If the 5G mobility management state of UE 704 is not defined, the lack of a properly defined 5G mobility management state during the timer's operating window may hinder the UE 704's ability to perform the registration procedure for disaster roaming services.

[0092] Therefore, user equipment 704 can transition to a specific 5G mobility management state based on its current registration status. If user equipment 704 is in the 5G mobility management - registration state. PLMN search state 804, it can transition to the 5G mobility management registration state. Attempt registration update state 806. If user equipment 704 is in the 5G mobility management - deregistration state. PLMN search state 834, it can enter the 5G mobility management deregistration state. Attempt registration state 836.

[0093] When the disaster roaming wait timer expires, user equipment 704 enters the 5G Mobility Management - Registration Initiated (5GMM-REGISTERED-INITIATED) state 808 and initiates the registration procedure for disaster roaming service with the public land mobile network 720. If registration is successful, user equipment 704 enters the 5G Mobility Management - Registration - Normal Service (5GMM-REGISTERED.NORMAL-SERVICE) state with the public land mobile network 720 and can access the provided services.

[0094] Before the disaster situation ends, user equipment 704 may enter 5G mobility management-cancellation state 820 for various reasons. For example, due to factors such as network infrastructure damage, power outages, or user equipment 704 being moved out of the coverage area, user equipment 704 may lose coverage from the disaster-use public terrestrial mobile network 720. If user equipment 704 is unable to re-establish a connection with the disaster-use public terrestrial mobile network 720 or any other available network, it will transition to 5G mobility management-cancellation state 820.

[0095] Furthermore, when the disaster situation ends, the disaster-use public terrestrial mobile network 720 may explicitly deregister user equipment 704. This may be for the purpose of effectively managing network resources and prompting user equipment 704 to search its regular public terrestrial mobile network 710 or other available networks. Upon receiving a deregistration request from the network, user equipment 704 will enter 5G mobility management - deregistration state 820.

[0096] When the disaster situation ends, user equipment 704 decides to execute a public land mobile network selection procedure to return to its regular public land mobile network 710. If user equipment 704 is in a 5G mobility management-registration state 810 with disaster-use public land mobile network 720, it will transition to a 5G mobility management-registration state 812 to search for the regular public land mobile network 710. If user equipment 704 is in a 5G mobility management-deregistration state 820 when the disaster situation ends, it will transition to a 5G mobility management-deregistration state 838 to search for the regular public land mobile network 710.

[0097] Once user equipment 704 selects the regular public terrestrial mobile network 710 for registration, it will start a timer with a randomly generated value in state 812 or state 838, within the disaster return waiting range. This timer is designed to prevent network congestion by distributing the return registration attempts of user equipment over time.

[0098] During the timer's running window, the 5G mobility management state of user equipment 704 should be clearly defined in order to facilitate the registration process when the timer expires.

[0099] If user equipment 704 is in the 5G Mobility Management - Registration state .PLMN Search state 812 when the timer starts, user equipment 704 enters the 5G Mobility Management Registration state .Attempt Registration Update state 814 during the disaster return waiting timer. User equipment 704 is preparing to start the registration process when the timer expires.

[0100] If user equipment 704 is in 5G Mobility Management - Deregistration state when the timer starts, PLMN search state 838, user equipment 704 enters 5G Mobility Management Deregistration state during the disaster return waiting timer's running window, PLMN search state 840.

[0101] When the disaster return waiting timer expires, user equipment 704 initiates the registration procedure with the regular public terrestrial mobile network 710. If registration is successful, user equipment 704 enters the 5G mobility management-registration state with the regular public terrestrial mobile network 710, normal service state 802, indicating a successful return to its home network.

[0102] As described above, when user equipment 704 selects to use the public terrestrial mobile network 720 for disaster roaming, it will start a timer with a randomly generated value within the disaster roaming waiting period. During the timer's operating window, the 5G mobility management state of user equipment 704 should be explicitly defined to facilitate the appropriate operation and registration procedures for disaster roaming services when the timer expires.

[0103] In certain configurations, user equipment 704 can transition to a specific 5G mobility management (MLM) state based on its current registration status. If user equipment 704 is in the 5G Mobility Management - Registration state.PLMN search state 804, it can transition to one of the following states: 5G Mobility Management - Registration state. Normal service state, 5G Mobility Management - Registration state. Attempting registration update state, 5G Mobility Management - Registration state. Required update (5GMM-REGISTERED.UPDATE-NEEDED) state, and 5G Mobility Management - Deregistration state. Disaster roaming wait (5GMM-REGISTERED.DISASTER-ROAMING-WAITING) state. The 5G Mobility Management - Deregistration state.Disaster roaming wait is a new state indicating that user equipment 704 has registered and is waiting for the disaster roaming wait timer to expire, and then attempts to register with the public terrestrial mobile network 720 in the event of a disaster.

[0104] If user equipment 704 is in the 5G Mobility Management - Deregistered state.PLMN search state 834, it can transition to one of the following states: 5G Mobility Management - Deregistered state. Normal service state, 5G Mobility Management - Deregistered state. Attempted registration state, 5G Mobility Management - Deregistered state. Initial registration required (5GMM-DEREGISTERED.INITIAL-REGISTRATION-NEEDED) state, and 5G Mobility Management - Deregistered state. Disaster roaming pending state. The 5G Mobility Management - Deregistered state. Disaster roaming pending state is a new state indicating that user equipment 704 has been deregistered and is waiting for the disaster timer to expire before attempting registration.

[0105] During the disaster roaming wait timer's run window, user equipment 704 does not initiate any 5G mobility management procedures, except for emergency services. This restriction helps prevent network congestion, enabling disaster use of the public land mobile network 720 to effectively manage the influx of disaster roaming requests. As described above, when the disaster situation ends, user equipment 704 decides to execute a public land mobile network selection procedure to return to its regular public land mobile network 710, and it initiates a disaster return wait timer. During this timer's run window, the 5G mobility management state of user equipment 704 should be clearly defined to facilitate the execution of the registration procedure when the timer expires.

[0106] If user equipment 704 is in 5G Mobility Management - Registration state. PLMN search state 812, it can transition to one of the following states: 5G Mobility Management - Deregistration state. Normal service state, 5G Mobility Management Deregistration state. Attempted registration state, 5G Mobility Management - Deregistration state. Initial registration required state, and 5G Mobility Management - Deregistration state. Disaster roaming pending state.

[0107] If user equipment 704 is in 5G Mobility Management - Cancelled State. PLMN Search State 838, it can transition to one of the following states: 5G Mobility Management - Cancelled State. Normal Service State, 5G Mobility Management - Cancelled State. Attempted Registration State, 5G Mobility Management - DEREGISTERED. INITIAL - REGISTRATION - NEEDED State, and 5G Mobility Management - Cancelled State. Disaster Roaming Waiting State.

[0108] Similar to the behavior during a disaster roaming wait timer, in the state entered during the disaster return wait timer's running window, user equipment 704 does not initiate any 5G mobility management procedures, except for emergency services. This restriction helps prevent network congestion in the regular public terrestrial mobile network 710, as multiple user equipment attempts to return to their home network simultaneously.

[0109] In another aspect, user equipment 704 can store or remember its 5G mobility management state before performing public terrestrial mobile network selection for disaster roaming. This allows user equipment 704 to restore its previous 5G mobility management state after public terrestrial mobile network selection is completed and after the disaster roaming wait timer or disaster return wait timer starts or runs.

[0110] When the random timer is running within the disaster roaming wait range or disaster return wait range and a public terrestrial mobile network is selected, user equipment 704 enters a specific 5G mobility management state. This state is selected by user equipment 704 while the wait timer related to the disaster situation is running.

[0111] Before initiating the public land mobile network selection procedure, user equipment 704 stores or remembers its current 5G mobility management state. This stored state information is retained by user equipment 704 during the public land mobile network selection process. Once the public land mobile network selection is complete, whether by selecting public land mobile network 720 for disaster roaming or selecting regular public land mobile network 710 to return from disaster roaming, and the corresponding wait timer starts or runs, user equipment 704 retrieves the stored 5G mobility management state information.

[0112] Then, user equipment 704 transitions to the stored 5G mobility management state, continuing its previous state before the public terrestrial mobile network selection occurred.

[0113] During or after the random timer runs, user equipment 704 does not initiate any 5G mobility management procedures, except for emergency services.

[0114] On the other hand, when the random timer is running in the disaster roaming wait range or disaster return wait range and a public terrestrial mobile network is selected, the user equipment 704 can maintain its current 5G mobility management state. The user equipment 704 may remain in the same 5G mobility management state, such as 5G Mobility Management - Registration State.PLMN Search State 804 or 5G Mobility Management - Deregistration State.PLMN Search State 834, while the disaster roaming random timer is started or running.

[0115] By maintaining the same 5G mobility management state during the disaster roaming wait timer or disaster return wait timer, user equipment 704 maintains a consistent 5G mobility management state throughout the entire disaster roaming wait period.

[0116] During or after the random timer runs, user equipment 704 does not initiate any 5G mobility management procedures, except for emergency services.

[0117] Figure 9 This is a flowchart 900 of a method for managing disaster roaming procedures in an emergency. The method can be performed by a user equipment (e.g., user equipment 704). In operation 902, the user equipment receives a list of public terrestrial mobile networks from the network for disaster situations.

[0118] In operation 904, the user equipment detects a disaster situation affecting its registration with a public land mobile network (e.g., regular public land mobile network 710). In some configurations, the user equipment detects the disaster situation based on a system information block indicating the disaster situation. In operation 906, the user equipment selects a network for disaster roaming based on a received list. In some configurations, the selected network is a public land mobile network (e.g., disaster-use public land mobile network 720). Furthermore, the selected disaster roaming public land mobile network might be a disabled public land mobile network for the user equipment under normal circumstances.

[0119] In Operation 908, the User Equipment (UE) starts a timer with a randomly generated value within the disaster roaming wait range. In some configurations, the disaster roaming wait range is provided to the UE by the network. In some configurations, the UE stores the disaster roaming wait range in the UE's non-volatile memory.

[0120] In Operation 910, the user equipment enters the first 5G mobility management state while the timer is running. The first 5G mobility management state is either a 5G mobility management deregistration state (attempting registration) when the user equipment is in a deregistration state, or a 5G mobility management registration state (attempting registration update) when the user equipment is in a registration state. In Operation 912, the user equipment avoids initiating any 5G mobility management procedures while the timer is running, except for emergency services. In Operation 914, the user equipment executes the disaster roaming service registration procedure when the timer expires.

[0121] Figure 10 This is a flowchart 1000 describing a method for managing disaster roaming procedures upon the end of a disaster situation. This method can be performed by a user equipment (e.g., user equipment 704). In operation 1002, the user equipment determines that the disaster situation has ended. In some configurations, the user equipment determines that the disaster situation has ended based on a System Information Block (SIB) indicating the end of the disaster situation.

[0122] In operation 1004, the user equipment selects a network to return from disaster roaming. In some configurations, the selected network is a Public Land Mobile Network (PLMN). In some configurations, the selected PLMN is the PLMN that the user equipment registered with before the disaster (e.g., a regular PLMN 710). In operation 1006, the user equipment starts a timer with a randomly generated value within the disaster return waiting range. In some configurations, the disaster return waiting range is provided to the user equipment by the network. In some configurations, the user equipment stores the disaster return waiting range in the user equipment's non-volatile memory.

[0123] In operation 1008, the user equipment enters the first 5G Mobility Management (5GMM) state while the timer is running. The first 5G Mobility Management state is either the 5G Mobility Management deregistration state (attempted registration state) when the user equipment is in a deregistration state, or the 5G Mobility Management registration state (attempted registration update state) when the user equipment is in a registration state. In operation 1010, the user equipment avoids initiating any 5G Mobility Management procedures while the timer is running, except for emergency services. In operation 1012, the user equipment performs a registration procedure on the selected public terrestrial mobile network when the timer expires.

[0124] It is understood that the specific order or hierarchy of blocks in the disclosed process / flowchart is an illustration of exemplary methods. Based on design preferences, it is understood that the specific order or hierarchy of blocks in the process / flowchart can be rearranged. Furthermore, some blocks can be merged or omitted. The appended method claims present the elements of the various blocks in an illustrative order and are not intended to limit one to the specific order or hierarchy presented.

[0125] The foregoing description is provided to any person skilled in the art to implement the various aspects described herein. Various modifications to these aspects will be apparent to a person 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 rather to give full scope consistent with the language of the claims, wherein a reference to a single element does not mean “only one,” but rather “one or more,” unless otherwise stated. The term “exemplary” as used herein means “as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or superior to other aspects. Unless otherwise stated, the term “some” means one or more. Combinations such as “at least one A, B, or C,” “one or more A, B, or C,” “at least one A, B, and C,” “one or more 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 A, B, or C,” “one or more A, B, or C,” “at least one A, B, and C,” “one or more A, B, and C,” and “A, B, C, or any combination thereof” can be A only, B only, C only, A and B, A and C, B and C, or A and B and C, wherein any such combination may contain one or more members of A, B, or C. All elements with structural and functional equivalents to the aspects described herein, which are known or subsequently known to those skilled in the art, are expressly incorporated herein by reference and are 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. The terms “module,” “mechanism,” “element,” “device,” etc., may not be substitutes for the term “means.” Therefore, unless an element expressly uses the term “means for,” no claim element should be construed as means plus function.

Claims

1. A wireless communication method for a user equipment, comprising: Choose a network for disaster roaming; Start a timer that generates a random value within the disaster roaming waiting range; When the timer runs, it enters the first 5G mobility management state, wherein the first 5G mobility management state is: When a user equipment is in a deregistered state, it is in the 5G Mobility Management - Deregistered state. Attempting Registration (5GMM - DEREGISTERED - ATTEMPTING - REGISTRATION) state; or When the user equipment is in the registration state, it is in the 5G Mobility Management - Registration state. Attempting Registration Update (5GMM-REGISTERED.ATTEMPTING-REGISTRATION-UPDATE) state; and While this timer is running, avoid initiating any 5G mobility management procedures except for emergency services.

2. The method of claim 1, further comprising: The registration process for disaster roaming services will be completed when the timer expires.

3. The method of claim 1, wherein the disaster roaming wait range is provided to the user equipment by the network.

4. The method of claim 1, further comprising: The disaster roaming wait range is stored in the user device's non-volatile memory.

5. The method of claim 1, further comprising: The system detects disaster situations that affect user equipment registration on public land mobile networks, where the network involved in disaster roaming is a public land mobile network selected after the disaster situation is detected.

6. The method of claim 5, wherein detecting the disaster situation includes receiving a system information block indicating the disaster situation.

7. The method of claim 1, further comprising: Receive a list of public land mobile networks for disaster situations from the network, wherein the selection of public land mobile networks for disaster roaming is based on the received list.

8. The method of claim 7, wherein the selection of the public land mobile network for disaster roaming is normally a disabled public land mobile network for the user equipment.

9. A wireless communication method for a user equipment, comprising: The disaster situation has been confirmed to be over; Choose a network to return from disaster roaming; Start a timer that generates a random value within the disaster return waiting range; When the timer runs, it enters the first 5G mobility management state, wherein the first 5G mobility management state is: When a user equipment is in a deregistered state, it is in the 5G Mobility Management - Deregistered state. Attempting Registration (5GMM - DEREGISTERED - ATTEMPTING - REGISTRATION) state; or When the user equipment is in the registration state, it is in the 5G Mobility Management - Registration state. Attempting Registration Update (5GMM-REGISTERED.ATTEMPTING-REGISTRATION-UPDATE) state; and While this timer is running, avoid initiating any 5G mobility management procedures except for emergency services.

10. The method of claim 9, wherein the network returning from disaster roaming is a public terrestrial mobile network, the method further comprising: When the timer expires, the registration process will be performed on the selected public land mobile network.

11. The method of claim 9, wherein the disaster return waiting range is provided to the user equipment by the network.

12. The method of claim 9, further comprising: The disaster return wait range is stored in the user equipment's non-volatile memory.

13. The method of claim 9, wherein determining that the disaster situation has ended includes receiving a system information block indicating that the disaster situation has ended.

14. The method of claim 9, wherein the selected public land mobile network was the registered public land mobile network of the user equipment prior to the disaster situation.

15. An apparatus for wireless communication, the apparatus being a user equipment, comprising: A memory; as well as At least one processor coupled to the memory is configured as follows: Choose a network for disaster roaming; Start a timer that generates a random value within the disaster roaming waiting range; When the timer runs, it enters the first 5G mobility management state, wherein the first 5G mobility management state is: When a user equipment is in a deregistered state, it is in the 5G Mobility Management - Deregistered state. Attempting Registration (5GMM - DEREGISTERED - ATTEMPTING - REGISTRATION) state; or When the user equipment is in the registration state, it is in the 5G Mobility Management - Registration state. Attempting Registration Update (5GMM-REGISTERED.ATTEMPTING-REGISTRATION-UPDATE) state; and While this timer is running, avoid initiating any 5G mobility management procedures except for emergency services.

16. The device of claim 15, wherein the at least one processor is further configured to: The registration process for the disaster roaming service will be executed when the timer expires.

17. The device of claim 15, wherein the disaster roaming wait range is provided to the user device by the network.

18. The device of claim 15, wherein at least one processor is further configured to store the disaster roaming wait range in the non-volatile memory of the user equipment.

19. The apparatus of claim 15, wherein at least one processor is further configured to: detect a disaster affecting the user equipment's registration with a public terrestrial mobile network, wherein the network for disaster roaming is a public terrestrial mobile network, wherein the public terrestrial mobile network is selected when the disaster is detected.

20. The apparatus of claim 19, wherein, in order to detect a disaster situation, at least one processor is further configured to: receive a system information block indicating a disaster situation.

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