Wireless communication method and device thereof

Abstract

The invention discloses a wireless communication method and a wireless communication device. Wherein the method comprises receiving, by a user equipment (UE), an indication of a change in timing synchronization state of a radio access network (RAN) from a network when at least a first timer and a second timer are running on the UE. The first timer is associated with a registration attempt counter or a registration procedure. The second timer is associated with a service request attempt counter or a service request program. In response to receiving the indication, the UE starts at least one registration procedure and service request procedure of the network when at least one of the first timer and the second timer is running.

Description

Technical Field

[0001] The present disclosure generally relates to wireless communication systems, and more particularly to techniques for managing radio access network (RAN) timing synchronization state changes in a congested network environment. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Wireless communication systems are widely deployed to provide a variety of telecommunication services such as telephony, video, data, messaging, and broadcast. A typical wireless communication system may employ multiple access technologies capable of supporting communications with multiple users by sharing the 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.

[0004] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a municipal, national, regional, or even global level. An example telecommunication standard is the fifth generation New Radio (5G New Radio, NR). 5G NR is part of the continued mobile broadband evolution promoted by the Third Generation Partnership Project (3GPP) to meet requirements related to latency, reliability, security, scalability (e.g., related to the Internet of Things (IoT)), and other requirements. Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There is a need for further improvements to the 5G NR technology. These improvements also apply to other multiple access technologies and the telecommunication standards that adopt them. Summary of the invention

[0005] A simplified summary of one or more aspects is presented below to provide a basic understanding of these aspects. This summary is not an extensive overview of all contemplated aspects, and its purpose is neither to identify the key or core components 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 preceding description of a more detailed description provided later.

[0006] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a user equipment (UE). When at least one first timer and a second timer are running on the user equipment, the user equipment receives an indication of a change in a timing synchronization state of a radio access network (RAN) from a network. The first timer is associated with a registration attempt counter or a registration procedure. The second timer is associated with a service request attempt counter or a service request procedure. In response to receiving the indication, the user equipment starts at least one registration procedure and a service request procedure of the network when at least one first timer and the second timer are running.

[0007] To achieve the above and related purposes, one or more aspects include the features fully described and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail some illustrative features of one or more aspects. However, these features illustrate only one of several ways to use the principles of the various aspects, and this description is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A diagram showing an example wireless communication system and access network.

[0009] Figure 2 Diagram showing a base station communicating with a user equipment (UE) in an access network.

[0010] Figure 3 An example logical architecture of a distributed access network is presented.

[0011] Figure 4 An example physical architecture of a distributed access network is shown.

[0012] Figure 5 Diagram showing an example of downlink (DL) centric time slots.

[0013] Figure 6 Diagram showing an example of uplink (UL) centric time slots.

[0014] Figure 7 Diagram showing a user equipment (UE) communicating with a base station of a public land mobile network (PLMN).

[0015] Figure 8 Diagram showing an example scenario in which a user equipment (UE) receives an indication of a change in the radio access network (RAN) timing synchronization state while the T3502 timer is running and initiates a registration procedure.

[0016] Fig. 9An example scenario diagram showing that a user equipment (UE) receives an indication of a change in the radio access network (RAN) timing synchronization state while the T3525 timer is running and initiates a service request procedure.

[0017] Fig.10 An example scenario diagram showing that the T3346 timer is running when a user equipment (UE) receives an indication of a change in the radio access network (RAN) timing synchronization state.

[0018] Fig.11 Flowchart of a method (process) of managing Radio Access Network (RAN) timing synchronization state changes. DETAILED DESCRIPTION

[0019] The following detailed description is presented in conjunction with the accompanying drawings and is intended to describe various configurations, but does not represent that the described concepts can only be practiced in these configurations. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, for those skilled in the art, these concepts can be practiced without these specific details. In some cases, in order to avoid obscuring these concepts, known structures and components are shown in block diagram form.

[0020] Several aspects of telecommunication systems will be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and depicted in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "components"). These components can be implemented using electronic hardware, computer software, or any combination of the two. Whether these components are implemented as hardware or software depends on the specific application and design constraints imposed on the overall system.

[0021] For example, a component, any portion of a component, or any combination of components may be implemented as a "processing system" that includes 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 (SoC), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, etc., as well as other hardware suitable for performing the various functions described herein. One or more processors in a processing system may execute software. Software should be broadly understood to mean instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, processes, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0022] Thus, in one or more example aspects, the functions described may be implemented in hardware, software, or any combination of the two. If implemented in software, the functions may be stored or encoded as one or more instructions or codes stored on a computer-readable medium. Computer-readable media include computer storage media. The storage medium may be any available medium that a computer can access. For example, and not limited to, such a computer-readable medium may include a random access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, a combination of the above types of computer-readable media, or any other medium that can be used to store instructions or data structures in the form of computer executable code that can be accessed by a computer.

[0023] Figure 1 1 is a diagram of an example wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, user equipment (UEs) 104, an Evolved Packet Core (EPC) 160, and another core network 190 (e.g., a fifth generation core (5G Core, 5GC)). The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a home cell, a pico cell, and a micro cell.

[0024] The base station 102 configured for 4G LTE (collectively referred to as the Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network (E-UTRAN)) can interface with the EPC 160 via a backend link 132 (e.g., an SI interface). The base station 102 configured for 5G NR (collectively referred to as the Next Generation RAN (NG-RAN)) can interface with the core network 190 via a backend link 184. Among other functions, the base station 102 can perform one or more of the following functions: transmission of user data, 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), user and device tracking, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations 102 may communicate with each other directly or indirectly (eg, through the EPC 160 or the core network 190) via a backend link 134 (eg, an X2 interface). The backend link 134 may be wired or wireless.

[0025] Base stations 102 may communicate wirelessly with user equipment (UEs) 104. Each base station 102 may provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a restricted group called a closed subscriber group (CSG). The communication link 120 between the base station 102 and the user equipment (UEs) 104 may include uplink (UL) (also known as reverse link) transmissions from the user equipment (UE) 104 to the base station 102 and / or downlink (DL) (also known as forward link) transmissions from the base station 102 to the user equipment (UE) 104. The 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 performed over one or more carriers. The base station 102 / UE 104 may use spectrum of up to 7 MHz bandwidth per carrier allocated in a carrier aggregation of a total of YxMHz (x component carriers) for transmission in each direction. The carriers may be adjacent or non-adjacent. For DL ​​and UL, the allocation of carriers may be asymmetric (for example, more or less carriers may be allocated for DL ​​than for UL). The component carriers may include one primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell) and the secondary component carrier may be referred to as a secondary cell (SCell).

[0026] Some user equipments (UEs) 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use the DL / UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be performed via various wireless D2D communication systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on IEEE 802.11 standards, LTE, or NR.

[0027] 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 communicating to determine whether the channel is available.

[0028] The small base station 102' may operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, the small base station 102' may adopt NR and use the same 5 GHz unlicensed spectrum as the Wi-Fi AP 150. The small base station 102' adopting NR in the unlicensed spectrum may enhance the coverage and / or increase the capacity of the access network.

[0029] The base station 102, whether a small base station 102' or a large base station (e.g., a macro base station), may include an eNB, a gNodeB (gNB), or other types of base stations. Some base stations, such as gNB 180, may communicate with UE 104 in traditional 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 may be referred to as a mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. The range of EHF is 30 GHz to 300 GHz, with a wavelength between 1 mm and 10 mm. Radio waves in this frequency band may be referred to as millimeter waves. Frequencies near mmW may drop to 3 GHz with a wavelength of 100 mm. The superhigh frequency (SHF) band is between 3 GHz and 30 GHz, also known as centimeter waves. Communications using mmW / near mmW radio frequency bands (e.g., 3 GHz-300 GHz) have extremely high path loss and short range. The mmW base station 180 may use beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range.

[0030] The base station 180 may send one or more beamformed signals in transmit directions 108a to the UE 104. The UE 104 may receive one or more beamformed signals in receive directions 108b from the base station 180. The UE 104 may also send one or more beamformed signals in transmit directions to the base station 180. The base station 180 may receive one or more beamformed signals in receive directions from the UE 104. The base station 180 / UE 104 may perform beam training to determine the best receive and transmit directions for the base station 180 / UE 104. The transmit and receive directions of the base station 180 may be the same or different. The transmit and receive directions of the UE 104 may be the same or different.

[0031] The EPC 160 includes 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. The MME 162 may communicate with a Home Subscriber Server (HSS) 174. The MME 162 is a control node that handles signals between the UEs 104 and the EPC 160. Typically, the MME 162 provides bearer and connection management. All user Internet protocol (IP) packets are transmitted through the Serving Gateway 166, which itself is connected to the PDN Gateway 172. The PDN Gateway 172 provides UE IP address allocation and other functions. The PDN Gateway 172 and the BM-SC 170 are connected to the IP Services 176. The IP services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), PS streaming services and / or other IP services. The BM-SC 170 may provide configuration and delivery functions for MBMS user services. The BM-SC 170 may serve as an entry point for content providers' MBMS transmissions, may be used to authorize and start MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS gateway 168 may be used to distribute MBMS traffic to base stations 102 that belong to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcast by a specific service, and may be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0032] 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 may communicate with the Unified Data Management (UDM) 196. The AMF 192 is a control node that processes signals between the UEs 104 and the core network 190. Typically, the SMF 194 provides QoS flow 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 is connected to the IP service 197. The IP service 197 may include the Internet, the intranet, the IP Multimedia Subsystem (IMS), the PS streaming media service, and / or other IP services.

[0033] 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 appropriate terminology. Base station 102 provides an access point for UEs 104 to enter EPC 160 or core network 190. Examples of UEs 104 include cellular phones, smart phones, session initiation protocol (SIP) phones, laptops, personal digital assistants (PDAs), satellite radios, global positioning systems, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablets, smart devices, wearable devices, vehicles, electric meters, gas pumps, large or small kitchen appliances, medical devices, implants, sensors / actuators, displays, or any other device with similar functionality. Some UEs 104 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, subscription station, mobile unit, subscription unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscription station, access terminal, mobile terminal, wireless terminal, remote terminal, handheld device, user agent, mobile client, client, or other appropriate terminology.

[0034] Although the present disclosure may refer to fifth generation new radio (5G NR), the present disclosure may also be applicable to other similar fields, such as long term evolution technology (LTE), long term evolution technology-advanced version (LTE-Advanced, referred to as LTE-A), code division multiple access (Code Division Multiple Access, referred to as CDMA), Global System for Mobile communications (Global System for Mobile communications, referred to as GSM), or other wireless / radio access technologies.

[0035] Figure 22 is a block diagram of a base station 210 communicating with a user equipment (UE) 250 in an access network. In the downlink (DL), IP packets from the evolved packet core (EPC) 160 may be provided to the controller / processor 275. The 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, the radio link control (RLC) layer, and the medium access control (MAC) layer. The controller / processor 275 provides RRC layer functions associated with system information (e.g., MIB, SIBs) broadcasting, RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), measurement configuration for cross-radio access technology (RAT) mobility, and UE measurement reporting; PDCP layer functions associated with header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functions associated with transmission of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions associated with 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 through HARQ, priority handling, and logical channel priority.

[0036] The transmit (TX) processor 216 and the receive (RX) processor 270 implement layer 1 functions associated with various signal processing functions. Layer 1, including the physical (PHY) layer, may include error detection of the transmission channel, forward error correction (FEC) encoding / decoding of the transmission channel, interleaving, rate matching, mapping to physical channels, modulation / demodulation of the physical channels, and MIMO antenna processing. The TX processor 216 handles the mapping of signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., a pilot) in the time and / or frequency domain, and then combined using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 274 may be used to determine the coding and modulation schemes, as well as to perform spatial processing. The channel estimate may come from a reference signal and / or channel condition feedback transmitted by the UE 250. Each spatial stream may then be provided to a different antenna 220 via a separate transmitter 218TX. Each transmitter 218TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0037] At the UE 250, each receiver 254RX receives a signal through its corresponding antenna 252. Each receiver 254RX recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 256. The TX processor 268 and the RX processor 256 implement layer 1 functions associated with various signal processing functions. The RX processor 256 may perform spatial processing on the information to recover any spatial streams predetermined for the UE 250. If multiple spatial streams are predetermined for the UE 250, they may be combined into a single OFDM symbol stream by the RX processor 256. The RX processor 256 then converts the OFDM symbol stream from the time domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. By determining the most likely signal constellation point transmitted by the base station 210, the symbols and reference signals on each subcarrier are recovered and demodulated. These soft decisions may be based on channel estimates calculated by the channel estimator 258. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted on the physical channel by the base station 210. The data and control signals are then provided to the controller / processor 259 which implements Layer 3 and Layer 2 functions.

[0038] The controller / processor 259 may be associated with a memory 260 that stores program codes and data. The memory 260 may be referred to as a computer readable medium. In the uplink (UL), the controller / processor 259 provides demultiplexing between transport and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller / processor 259 is also responsible for error detection using an ACK and / or NACK protocol to support hybrid automatic repeat request (HARQ) operations.

[0039] Similar to the functional description associated with DL transmission of the base station 210, the controller / processor 259 provides RRC layer functions associated with system information (e.g., MIB, SIBs) acquisition, RRC connection, and measurement reporting; PDCP layer functions associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functions associated with transmission of upper layer PDUs, error correction through ARQ, connection, segmentation and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs to TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel priority.

[0040] Channel estimates derived by the channel estimator 258 from a reference signal or feedback transmitted by the base station 210 may be used by the TX processor 268 to select an appropriate coding and modulation scheme and facilitate spatial processing. The spatial streams generated by the TX processor 268 may be provided to different antennas 252 via separate transmitters 254TX. Each transmitter 254TX may modulate an RF carrier with a corresponding spatial stream for transmission. UL transmissions are processed at the base station 210 in a manner similar to that associated with the receive function of the UE 250. Each receiver 218RX receives a signal through its corresponding antenna 220. Each receiver 218RX recovers the information modulated onto the RF carrier and provides the information to the RX processor 270.

[0041] The controller / processor 275 may be associated with a memory 276 that stores program codes and data. The memory 276 may be referred to as a computer readable medium. In the uplink (UL), the controller / processor 275 provides demultiplexing between transports and logical channels, packet reassembly, decryption, header decompression, control signal processing to recover IP packets from the user equipment (UE) 250. The IP packets from the controller / processor 275 may be provided to the EPC 160. The controller / processor 275 is also responsible for error detection using an ACK and / or NACK protocol to support HARQ operations.

[0042] New Radio (NR) may refer to a radio configured to operate according to a new air interface (e.g., a non-orthogonal frequency division multiple access (OFDMA) based air interface) or a fixed transport layer (e.g., non-Internet Protocol (IP)). NR may use orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on both the uplink and downlink, and may support half-duplex operation using time division duplex (TDD). NR may include enhanced mobile broadband (eMBB) services for wide bandwidths (e.g., over 80 MHz), millimeter wave (mmW) for high carrier frequencies (e.g., 60 GHz), massive MTC (mMTC) for non-backward compatible machine type communication (MTC) technologies, and / or mission critical services for ultra-reliable low latency communications (URLLC) services.

[0043] A single component carrier bandwidth can support 100MHz. In one example, NR resource blocks (RBs) can span 12 subcarriers with a subcarrier bandwidth of 60kHz and a duration of 0.25ms, or a bandwidth of 30kHz and a duration of 0.5ms (similarly, 50MHz BW is suitable for 15kHz SCS and a duration of 1ms). Each radio frame can consist of 10 subframes (10, 20, 40, or 80 NR time slots) with a length of 10ms. Each time slot can indicate the link direction (i.e., downlink (DL) or uplink (UL)) for data transmission, and the link direction of each time slot can be switched dynamically. Each time slot can include DL / UL data as well as DL / UL control data. NR's UL and DL time slots can be described below with respect to Figure 5 and Figure 6 is described in more detail in .

[0044] The NR radio access network (RAN) may include a central unit (CU) and distributed units (DUs). A NR base station (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 may be configured as access cells (ACells) or data-only cells (DCells). For example, the RAN (e.g., a central unit or a distributed unit) may configure the cell. DCells may be cells for carrier aggregation or dual connectivity and may not be used for initial access, cell selection / reselection, or switching. In some cases, DCells may not transmit synchronization signals (SS), and in some cases DCells may transmit SS. The NR base station may send a downlink signal to the UE to indicate the cell type. Based on the cell type indication, the UE may communicate with the NR base station. For example, the UE may determine the NR base station for cell selection, access, switching, and / or measurement based on the indicated cell type.

[0045] Figure 3An example logical architecture of a distributed RAN 300 is shown, according to aspects of the present invention. A 5G access node 306 may include an access node controller (ANC) 302. The ANC may be a central unit (CU) of the distributed RAN. The back-end interface to the next generation core network (NG-CN) 304 may terminate at the ANC. The back-end interface to adjacent 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 Bs, 5GNBs, APs or other terms). As described above, TRP may be used interchangeably with "cell".

[0046] TRPs 308 may be distribution units (DUs). TRPs may be connected 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 may be connected to multiple ANCs. A TRP may include one or more antenna ports. TRPs may be configured to serve UEs individually (e.g., dynamically selected) or jointly (e.g., joint transmission).

[0047] The local architecture of the distributed RAN 300 can be used to illustrate the fronthaul definition. The architecture can define fronthaul solutions that support 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 functionality and / or components with LTE. According to aspects, the next generation AN (NG-AN) 310 can support dual connectivity with NR. The NG-AN can share a common fronthaul for LTE and NR.

[0048] The architecture may enable cooperation between and among TRPs 308. For example, cooperation may be provisioned within a TRP and / or between TRPs by the ANC 302. Depending on aspects, an interface between TRPs may not be required / existent.

[0049] According to aspects, there may be dynamic configuration of split logical functions in the architecture of the distributed RAN 300. PDCP, RLC, MAC protocols can be flexibly placed in ANC or TRP.

[0050] Figure 4An example physical architecture of a distributed RAN 400 is shown, in accordance with aspects of the present disclosure. A centralized core network unit (C-CU) 402 may host core network functions. The C-CU may be centrally deployed. C-CU functions may be offloaded (e.g., to Advanced Wireless Services (AWS)) to handle peak capacity. A centralized RAN unit (C-RU) 404 may host one or more ANC functions. Optionally, the C-RU may host core network functions locally. The C-RU may have a distributed deployment. The C-RU may be closer to the edge of the network. A distribution unit (DU) 406 may host one or more TRPs. The DU may be located at the edge of the network and have radio frequency (RF) functions.

[0051] Figure 5 FIG. 500 is a diagram illustrating an example of a downlink (DL)-centric time slot. The DL-centric time slot may include a control portion 502. The control portion 502 may be present at an initial or beginning portion of the DL-centric time slot. The control portion 502 may include various scheduling information and / or control information corresponding to various portions of the DL-centric time slot. In some configurations, the control portion 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 communicating downlink data from a scheduling entity (e.g., a UE or a BS) to a subordinate entity (e.g., a UE). In some configurations, the downlink data portion 504 may be a physical downlink shared channel (PDSCH).

[0052] 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 appropriate terms. The common uplink portion 506 may include feedback information corresponding to various 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. Non-limiting examples of feedback information may include an ACK signal, a NACK signal, a HARQ indicator, and / or various other appropriate types of information. The common uplink portion 506 may include additional or alternative information, such as information related to a random access channel (RACH) procedure, scheduling requests (SRs), and various other appropriate types of information.

[0053] like Figure 5 As shown, the end of the downlink data portion 504 may be separated in time from the beginning of the common uplink portion 506. This time separation may sometimes be referred to as a gap, a guard period, a guard interval, and / or other appropriate terms. This separation provides time for switching from downlink communications (e.g., reception operations by a subordinate entity (e.g., a UE)) to uplink communications (e.g., transmissions by a subordinate entity (e.g., a UE)). Those of ordinary skill in the art will appreciate that the above is merely an example of a downlink-centric time slot, and that alternative structures with similar features may exist without necessarily departing from the aspects described herein.

[0054] Figure 6 600, illustrating an example uplink (UL) centric timeslot. The uplink centric timeslot may include a control portion 602. The control portion 602 may be present at the beginning or start of the uplink centric timeslot. Figure 6 The control portion 602 in the above reference may be Figure 5 The control portion 502 described is similar. The uplink-centric timeslot 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 timeslot. The uplink portion may refer to the communication resources used to communicate uplink data from a subordinate entity (e.g., a UE) to a scheduling entity (e.g., a UE or a BS). In some configurations, the control portion 602 may be a physical downlink control channel (PDCCH).

[0055] like Figure 6As shown, the end of the control portion 602 may be separated in time from the beginning of the uplink data portion 604. This time separation may sometimes be referred to as a gap, a guard period, a guard interval, and / or other appropriate terms. This separation provides time for switching from downlink communications (e.g., reception operations by a scheduling entity) to uplink communications (e.g., transmissions by a scheduling entity). The uplink-centric timeslot may also include a common uplink portion 606. Figure 6 The common uplink portion 606 in the above reference may be the same as Figure 5 The common uplink portion 506 is similar to the common uplink portion 506 described above. The common uplink portion 606 may also or alternatively include information related to a channel quality indicator (CQI), a sounding reference signal (SRSs), and various other suitable types of information. It will be appreciated by those skilled in the art that the above is merely an example of an uplink-centric timeslot, and that alternative structures with similar features may exist without necessarily departing from the aspects described herein.

[0056] In some cases, two or more slave entities (e.g., UEs) may communicate with each other using sidelink signals. Real-world applications of such sidelink communications may include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communications, Internet of Everything (IoE) communications, Internet of Things (IoT) communications, mission-critical mesh networks, and / or various other appropriate applications. Generally, a sidelink signal may refer to a signal communication from one slave entity (e.g., UE1) to another slave entity (e.g., UE2) without relaying the communication through a scheduling entity (e.g., UE or BS), even though the scheduling entity may be used for scheduling and / or control purposes. In some examples, the sidelink signal may use licensed spectrum for communication (unlike wireless local area networks that typically use unlicensed spectrum).

[0057] In 5G networks, the Radio Access Network (RAN) timing synchronization status refers to the timing synchronization between nodes involved in network operations, such as NG-RAN nodes and NW-TTs (Network Time Translators). Timing synchronization can be based on 5G access layer based time distribution or (g)PTP based time distribution ((Generalized) Precision Time Protocol).

[0058] The RAN timing synchronization status may change depending on various factors in the network. When the RAN timing synchronization status changes, the network can request UEs (user equipment) that support reconnection due to the RAN timing synchronization status change to reconnect to the network. By reconnecting, UEs can obtain updated timing synchronization information and align their timing with the network. This is done using the 5G Mobility Management (5GMM) protocol.

[0059] Figure 7700, illustrating communication between a UE 704 and a base station of a PLMN 710. In this example, the UE 704 is in a 5GMM-connected mode with a radio resource control (RRC) inactive indication or a 5GMM-idle mode. In the 5GMM-connected mode with an RRC inactive indication, a non-access stratum (NAS) signaling connection is established, but the RRC connection is inactive. This means that the UE 704 has a signaling connection with the 5G core network (5GC) of the PLMN 710, but does not have an active radio connection with the base station 702. Similarly, in the 5GMM-idle mode, the UE 704 does not have an active NAS signaling connection or an active RRC connection. The UE 704 is in a low power consumption state and is not actively communicating with the PLMN 710. Therefore, in both modes, when the UE 704 receives an indication of a change in RAN timing synchronization state from the PLMN 710 through the base station 702, the UE 704 needs to reconnect with the PLMN 710 to obtain updated timing synchronization information and align its timing with the network.

[0060] In the first technique, when a user equipment (UE) receives an indication of a change in radio access network (RAN) timing synchronization status from the network, if any of timers T3346, T3502 or T3525 is running and the UE is in fifth generation mobility management (5GMM)-connected mode with radio resource control (RRC) inactivity indication or 5GMM-idle mode, no registration or service request (SR) procedure is allowed to reconnect to the network.

[0061] Timers T3502 and T3525 are associated with the registration attempt counter and the service request attempt counter, respectively. T3502 is started when the registration attempt counter reaches its maximum value (e.g., 5), while T3525 is started when the service request attempt counter is greater than or equal to 5. T3346 is a congestion timer that the UE starts when it receives a cause value of 22 (congestion) from the network.

[0062] Therefore, in this case, even if PLMN 710 expects UE 704 to reconnect, UE 704 is not allowed to start the registration or SR procedure. This causes the state between UE 704 and PLMN 710 to be out of sync, because PLMN 710 continues to wait for UE 704 to reconnect, but UE 704 is not allowed to do so because the timer is running.

[0063] However, waiting for the timer to expire may take a considerable amount of time (e.g., T3502 exceeds 30 minutes). This would cause the network to wait indefinitely for a response from the UE, defeating the purpose of sending a reconnect indication. Furthermore, the T3346 timer is associated with network congestion, and if the network requests the UE to send a message, this implicitly indicates that the UE should be allowed to do so regardless of the timer status.

[0064] Figure 8 800, illustrating an example scenario in which the UE initiates a registration procedure after receiving an indication of a change in RAN timing synchronization state while timer T3502 is running. An example of starting timer T3502 when UE 704 performs mobility and periodic registration update procedures. If the registration attempt counter is equal to 5, UE 704 needs to start timer T3502 (if the timer value indicated by the network (e.g., PLMN 710) is not zero) and set the 5GS update status to 5U2 NOTUPDATED.

[0065] In this example, at time point t0, UE 704 begins attempting a registration procedure for mobility and periodic registration updates with PLMN 710 through base station 702. UE 704 may be in 5GMM-connected mode with RRC inactivity indication or 5GMM-idle mode. At time point t1, UE 704 attempts multiple times (up to 5 times) but does not receive a successful response from PLMN 710. Therefore, UE 704 starts the T3502 timer to prevent further attempts for a specific duration indicated by the network. During this period, UE 704 considers its registration status not updated (5U2 NOT UPDATED).

[0066] At time t2, when timer T3502 of UE 704 is running, PLMN 710 experiences a change in RAN timing synchronization status. PLMN 710 sends an indication of this change to UE 704 via base station 702, requesting UE 704 to reconnect to the network to obtain updated timing synchronization information.

[0067] In the second technique, even if timer T3502 is running, UE 704 is allowed to initiate a registration procedure after receiving an indication of a change in RAN timing synchronization status from PLMN 710. Therefore, UE 704 can quickly respond to PLMN 710's request to reconnect and obtain updated timing synchronization information, thereby maintaining synchronization between UE 704 and PLMN 710.

[0068] By allowing UE 704 to start the registration procedure while timer T3502 is running, the second technique overcomes the limitation of the first technique and enables UE 704 to reconnect to PLMN 710 in a timely manner. This prevents PLMN 710 from waiting indefinitely for a response from UE 704 and achieves the purpose of sending a reconnection indication.

[0069] Therefore, at time point t3, even though timer T3502 is still running, UE 704 starts a registration procedure with PLMN 710 through base station 702. UE 704 sends a registration request message to PLMN 710, indicating that it supports reconnection due to RAN timing synchronization status change.

[0070] After receiving the registration request message, PLMN 710 recognizes that UE 704 is reconnecting in response to an indication of a change in RAN timing synchronization status. PLMN 710 processes the registration request and sends a registration accept message to UE 704 via base station 702. The registration accept message contains updated timing synchronization information that UE 704 needs to align timing with the network.

[0071] At time t4, UE 704 receives a registration accept message from PLMN 710. UE 704 extracts the updated timing synchronization information from the message and applies it to synchronize with the timing of PLMN 710. Therefore, UE 704 and PLMN 710 operate with the same timing reference, maintaining synchronization between them.

[0072] Fig. 9 900, illustrating an example scenario in which the UE initiates a service request procedure after receiving an indication of a change in RAN timing synchronization status while timer T3525 is running. During the service request procedure, when the UE 704 sends a service request message, timer T3517 is started. When timer T3517 expires, the UE 704 increments a service attempt counter. If the UE 704 does not receive a successful response from the PLMN 710 after multiple attempts (up to 5), timer T3525 is started to prevent further attempts for a specific duration.

[0073] In this example, at time t0, UE 704 begins attempting a service request procedure with PLMN 710 through base station 702. UE 704 sends a service request message to PLMN 710, indicating that it needs service or resources. UE 704 may be in 5GMM-connected mode with RRC inactivity indication or 5GMM-idle mode.

[0074] At time point t1, UE 704 attempts the service request procedure multiple times (up to 5 times) but does not receive a successful response from PLMN 710. Therefore, UE 704 starts timer T3525 to prevent further attempts for a specific duration.

[0075] At time t2, when timer T3525 of UE 704 is running, PLMN 710 experiences a change in RAN timing synchronization status. PLMN 710 sends an indication of this change to UE 704 via base station 702, requesting UE 704 to reconnect to the network to obtain updated timing synchronization information.

[0076] In the second technique, even if the timer T3525 is running, the user equipment (UE) 704 is allowed to initiate a service request procedure after receiving an indication of a change in the timing synchronization state of the radio access network (RAN) from the public land mobile network (PLMN) 710. This enables the user equipment (UE) 704 to quickly respond to the reconnection request of the public land mobile network (PLMN) 710 and obtain updated timing synchronization information to maintain synchronization between the user equipment (UE) 704 and the public land mobile network (PLMN) 710.

[0077] Therefore, at time point t3, even though timer T3525 is still running, user equipment (UE) 704 initiates a service request procedure with public land mobile network (PLMN) 710 through base station 702. User equipment (UE) 704 sends a service request message to public land mobile network (PLMN) 710, indicating that it supports reconnection due to the change in RAN timing synchronization status.

[0078] After receiving the service request message, the public land mobile network (PLMN) 710 recognizes that the user equipment (UE) 704 is reconnecting in response to an indication of a change in the RAN timing synchronization state. The public land mobile network (PLMN) 710 processes the service request and sends a service accept message to the user equipment (UE) 704 via the base station 702. The service accept message contains updated timing synchronization information that the user equipment (UE) 704 needs to align timing with the network.

[0079] At time point t4, the user equipment (UE) 704 receives a service acceptance message from the public land mobile network (PLMN) 710. The user equipment (UE) 704 extracts the updated timing synchronization information from the message and applies it to synchronize with the timing of the public land mobile network (PLMN) 710. As a result, the user equipment (UE) 704 and the public land mobile network (PLMN) 710 operate with the same timing reference, maintaining synchronization between them.

[0080] By allowing the user equipment (UE) 704 to initiate a service request procedure while the timer T3525 is running, the second technique overcomes the limitation of the first technique and enables the user equipment (UE) 704 to promptly reconnect to the public land mobile network (PLMN) 710. This prevents the public land mobile network (PLMN) 710 from waiting indefinitely for a response from the user equipment (UE) 704 and achieves the purpose of sending an indication to reconnect.

[0081] Fig.10 1000, illustrating an example scenario in which timer T3346 is running when a user equipment (UE) 704 receives an indication of a change in RAN timing synchronization state. Timer T3346 is a congestion timer that the user equipment (UE) 704 starts upon receiving a cause value 22 (congestion) from the network, i.e., the public land mobile network (PLMN) 710. The network uses timer T3346 to control the timing of reconnection attempts by the user equipment (UE) 704 during network congestion. When the network is congested, it may reject a service request or registration attempt by the user equipment and include the value of timer T3346 in the reject message. The user equipment (UE) 704 starts timer T3346 based on the value received in the reject message and waits for the timer to expire before attempting to reconnect to the network. This helps prevent further congestion by spreading out the timing of reconnection attempts.

[0082] In this example, at time t0, user equipment (UE) 704 attempts to establish a connection with a public land mobile network (PLMN) 710 through a base station 702, whether through a registration procedure or a service request procedure. The user equipment (UE) 704 sends a message to the public land mobile network (PLMN) 710 to request services or resources. The user equipment (UE) 704 may be in a fifth generation mobility management (5GMM)-connected mode with a radio resource control (RRC) inactive indication or a 5GMM-idle mode.

[0083] At time t1, the public land mobile network (PLMN) 710 experiences congestion and rejects the request of the user equipment (UE) 704. The public land mobile network (PLMN) 710 sends a rejection message to the user equipment (UE) 704 through the base station 702, including the cause value 22 (congestion) and the value of the timer T3346. The user equipment (UE) 704 starts the timer T3346 according to the value received in the rejection message.

[0084] At time t2, when timer T3346 on user equipment (UE) 704 is running, public land mobile network (PLMN) 710 experiences a change in RAN timing synchronization state. Public land mobile network (PLMN) 710 sends an indication of this change to user equipment (UE) 704 via base station 702, requesting user equipment (UE) 704 to reconnect to the network to obtain updated timing synchronization information.

[0085] In the second technique, even if the timer T3346 is running, the user equipment (UE) 704 is allowed to start a registration procedure or a service request procedure after receiving an indication of a change in the RAN timing synchronization state from the public land mobile network (PLMN) 710. This enables the user equipment (UE) 704 to quickly respond to the reconnection request of the public land mobile network (PLMN) 710 and obtain updated timing synchronization information to maintain synchronization between the user equipment (UE) 704 and the public land mobile network (PLMN) 710.

[0086] Therefore, at time point t3, even though timer T3346 is still running, user equipment (UE) 704 initiates a registration procedure or a service request procedure with public land mobile network (PLMN) 710 through base station 702. User equipment (UE) 704 sends a message to public land mobile network (PLMN) 710 according to the registration procedure or the service request procedure, indicating that it supports reconnection due to a change in the RAN timing synchronization state.

[0087] After receiving the message from the user equipment (UE) 704, the public land mobile network (PLMN) 710 recognizes that the user equipment (UE) 704 is reconnecting in response to an indication of a change in the RAN timing synchronization state. The public land mobile network (PLMN) 710 processes the message and sends a response message to the user equipment (UE) 704 via the base station 702. The response message contains updated timing synchronization information that the user equipment (UE) 704 needs to align timing with the network.

[0088] At time point t4, the user equipment (UE) 704 receives a response message from the public land mobile network (PLMN) 710. The user equipment (UE) 704 extracts the updated timing synchronization information from the message and applies it to synchronize with the timing of the public land mobile network (PLMN) 710. As a result, the user equipment (UE) 704 and the public land mobile network (PLMN) 710 operate with the same timing reference, maintaining synchronization between them.

[0089] By allowing the user equipment (UE) 704 to initiate a registration procedure or a service request procedure while the timer T3346 is running, the second technology overcomes the limitation of the first technology and enables the user equipment (UE) 704 to promptly reconnect to the public land mobile network (PLMN) 710. This prevents the public land mobile network (PLMN) 710 from waiting indefinitely for a response from the user equipment (UE) 704 and achieves the purpose of sending an indication to reconnect.

[0090] Fig.11 1100 is a flow chart illustrating a method (process) for managing a change in RAN timing synchronization state. The method may be performed by a user equipment (e.g., user equipment (UE) 704). In operation 1102, the user equipment receives an indication of a change in a radio access network (RAN) timing synchronization state from a network, while at least a first timer and a second timer are running on the user equipment. The first timer is associated with a registration attempt counter or a registration procedure, and the second timer is associated with a service request attempt counter or a service request procedure. In some configurations, the user equipment is in one of a fifth generation mobility management (5GMM)-connected mode with a radio resource control (RRC) inactive indication and a 5GMM-idle mode when receiving the indication.

[0091] In operation 1104, in response to receiving the indication, a user equipment (UE) initiates at least one registration procedure and a service request procedure of the network when at least one first timer and a second timer are running on the UE. In some configurations, the first timer is initiated when the registration attempt counter reaches a maximum value. In some configurations, the maximum value is 5. In some configurations, the first timer is a T3502 timer. In some configurations, the second timer is initiated when the service request attempt counter reaches a maximum value. In some configurations, the maximum value is 5. In some configurations, the second timer is a T3525 timer.

[0092] In some configurations, in operation 1106, the user equipment (UE) initiates a registration procedure by sending a registration request message to the network to implement operation 1104. The registration request message indicates that the user equipment (UE) supports reconnecting to the network due to a change in the timing synchronization state of the radio access network (RAN). In operation 1108, the user equipment (UE) receives a registration accept message from the network in response to the registration request message. The registration accept message includes updated timing synchronization information. In operation 1110, the user equipment (UE) applies the updated timing synchronization information to synchronize the timing of the user equipment (UE) with the network.

[0093] In some configurations, in operation 1112, the user equipment (UE) initiates a service request procedure by sending a service request message to the network to implement operation 1104. The service request message indicates that the user equipment (UE) supports reconnection to the network due to a change in the timing synchronization state of the radio access network (RAN). In operation 1114, the user equipment (UE) receives a service acceptance message from the network in response to the service request message. The service acceptance message includes updated timing synchronization information. In operation 1116, the user equipment (UE) applies the updated timing synchronization information to synchronize the timing of the user equipment (UE) with the network.

[0094] Please understand that the specific order or hierarchy of blocks in the flowchart is merely an illustration of an exemplary method. The specific order or hierarchy of blocks in the flowchart may be rearranged based on design preferences. In addition, some blocks may be combined or omitted. The accompanying method claims present components of the various blocks in an exemplary order and are not meant to be limited to the specific order or hierarchy presented.

[0095] The foregoing description is intended to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Therefore, the purpose of the claims is not to be limited to the aspects shown herein, but to be given a full scope consistent with the language of the claims, wherein reference to a singular component does not mean "only one", unless specifically stated, but means "one or more". The word "example" used herein means "as an example, instance or illustration". Any aspect described as an "example" is not necessarily considered superior to other aspects. Unless otherwise expressly stated, the term "some" refers to 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" 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" may 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 structural and functional equivalents of the various aspects described herein, which are known or later known to one of ordinary skill in the art, are hereby incorporated by reference and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be disclosed, whether or not explicitly stated in the claims. Words such as "module," "mechanism," "component," "device," etc., shall not be substituted for the word "means." Therefore, any claim component shall not be interpreted as having a means for function unless the component is explicitly stated using the phrase "means for."

Claims

1. A wireless communication method of a user equipment, comprising: receiving an indication of a change in a timing synchronization state of a radio access network from a network when at least a first timer and a second timer are running on the user equipment, wherein the first timer is associated with a registration attempt counter or a registration procedure, and wherein the second timer is associated with a service request attempt counter or a service request procedure; as well as In response to receiving the indication, at least one registration procedure and a service request procedure of the network are initiated when at least one of the first timer and the second timer is running.

2. The method of claim 1, wherein the user equipment is in one of a fifth generation mobility management-connected mode and a radio resource control inactivity indication and a fifth generation mobility management-idle mode when receiving the indication.

3. The method of claim 1, wherein the first timer is started when the registration attempt counter reaches a maximum value. The method of claim 3 , wherein the maximum value is 5.

5. The method of claim 3, wherein the first timer is a T3502 timer. The method of claim 1 , wherein the second timer is started when the service request attempt counter reaches a maximum value. The method of claim 6 , wherein the maximum value is 5.

8. The method of claim 6, wherein the second timer is a T3525 timer.

9. The method of claim 1, wherein initiating the registration procedure comprises sending a registration request message to the network, the registration request message indicating that the user equipment supports reconnection to the network due to a change in the timing synchronization state of the radio access network.

10. The method of claim 9, further comprising receiving a registration accept message from the network in response to the registration request message, the registration accept message including updated timing synchronization information.

11. The method of claim 10, further comprising applying the updated timing synchronization information to synchronize the user equipment with the timing of the network.

12. The method of claim 1, wherein initiating the service request procedure comprises sending a service request message to the network, the service request message indicating that the user equipment supports reconnection to the network due to a change in the timing synchronization state of the radio access network.

13. The method of claim 12, further comprising receiving a service accept message from the network in response to the service request message, the service accept message including updated timing synchronization information.

14. The method of claim 13, further comprising applying the updated timing synchronization information to synchronize the user equipment with the timing of the network.

15. An apparatus for wireless communication, the apparatus being a user equipment, comprising: a memory; as well as At least one processor connected to the memory, configured to: receiving an indication of a change in a timing synchronization state of a radio access network from a network when at least one of a first timer and a second timer is running on the user equipment, wherein the first timer is associated with a registration attempt counter or a registration procedure, and wherein the second timer is associated with a service request attempt counter or a service request procedure; as well as In response to receiving the indication, at least one registration procedure and a service request procedure of the network are initiated when at least one of the first timer and the second timer is running.

16. The apparatus of claim 15, wherein the first timer is started when the registration attempt counter reaches a maximum value.

17. The apparatus of claim 15, wherein the second timer is started when the service request attempt counter reaches a maximum value.

18. The apparatus of claim 15, wherein the at least one processor is configured to initiate the registration procedure by sending a registration request message to the network, the registration request message indicating that the user equipment supports reconnection to the network due to a change in the timing synchronization state of the radio access network.

19. The apparatus of claim 15, wherein the at least one processor is configured to initiate the service request procedure by sending a service request message to the network, the service request message indicating that the user equipment supports reconnection to the network due to a change in the timing synchronization state of the radio access network.

20. A computer readable medium storing computer executable code for wireless communication of a user device, comprising code to: receiving an indication of a change in a timing synchronization state of a radio access network from a network when at least one of a first timer and a second timer is running on the user equipment, wherein the first timer is associated with a registration attempt counter or a registration procedure, and wherein the second timer is associated with a service request attempt counter or a service request procedure; and In response to receiving the indication, at least one registration procedure and a service request procedure are initiated with the network while at least one of the first timer and the second timer is running.

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