Terminal network access method, device, low-orbit narrowband satellite terminal and readable storage medium

Abstract

The present invention provides a terminal network access method, device, low-orbit narrowband satellite terminal and readable storage medium, which relate to the field of satellite communications. The method is: after power-on initialization, a main beam search is performed to determine a resident cell; a frequency point list corresponding to the resident cell is obtained, and a resident frequency point is determined from multiple frequency points in the frequency point list; based on the resident frequency point, registration interaction is performed with the satellite core network to complete network access registration and enter a standby state. In this way, a beam search is performed first, then the resident frequency point is determined, and then registration is performed, thereby realizing network access of a low-orbit narrowband satellite terminal.

Description

Technical Field

[0001] The present invention relates to the field of satellite communications, and in particular to a terminal network access method, a device, a low-orbit narrowband satellite terminal and a readable storage medium. Background Art

[0002] Satellites are divided into low-orbit satellites and high-orbit satellites according to their orbital altitudes. Among them, the characteristics of high-orbit satellites are: the operating cycle is the same as the Earth's rotation cycle (about 24 hours), so they are stationary relative to the ground; the coverage is wide, and a high-orbit satellite can cover about one-third of the Earth's surface; the transmission delay of high-orbit satellites is relatively high, about 240ms. The characteristics of low-orbit satellites are: the operating cycle is short, usually between 90 minutes and 120 minutes, so the satellite moves quickly over the Earth; the coverage is relatively small, and the transmission delay is low, about 20ms~40ms.

[0003] At present, my country's low-orbit satellites are in a stage of vigorous development. Under the coverage of low-orbit Internet constellations, they can provide broadband Internet access services to the ground. In low-orbit Internet constellations, how low-orbit satellite terminal products, especially low-orbit narrowband satellite terminals, can achieve network access is a question that needs to be considered. Summary of the invention

[0004] The object of the present invention is to provide a terminal network access method, device, low-orbit narrowband satellite terminal and readable storage medium to improve the problems existing in the prior art.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a terminal network access method, which is applied to a low-orbit narrowband satellite terminal, and the method comprises:

[0007] After power-on initialization, a main beam search is performed to determine the resident cell;

[0008] Acquire a frequency point list corresponding to the resident cell, and determine a resident frequency point from multiple frequency points in the frequency point list;

[0009] Based on the resident frequency point, registration interaction is performed with the satellite core network to complete network registration and enter a standby state.

[0010] In a second aspect, the present invention provides a terminal network access device, which is applied to a low-orbit narrowband satellite terminal, comprising:

[0011] A beam search module, used to perform a main beam search to determine a resident cell after power-on initialization;

[0012] The beam search module is used to obtain a frequency point list corresponding to the resident cell, and determine a resident frequency point from multiple frequency points in the frequency point list;

[0013] The registration module is used to perform registration interaction with the satellite core network based on the resident frequency point to complete the network registration and enter the standby state.

[0014] In a third aspect, the present invention provides a low-orbit narrowband satellite terminal, comprising: a memory and a processor, wherein the memory stores a software program, and when the low-orbit narrowband satellite terminal is running, the processor executes the software program to implement the terminal network access method as described in the first aspect above.

[0015] In a fourth aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the terminal network access method described in the first aspect is implemented.

[0016] Compared with the prior art, the embodiments of the present invention provide a terminal network access method, device, low-orbit narrowband satellite terminal and readable storage medium. The method is: after power-on initialization, perform main beam search to determine the resident cell; obtain the frequency point list corresponding to the resident cell, and determine the resident frequency point from the multiple frequency points in the frequency point list; register and interact with the satellite core network based on the resident frequency point to complete the network access registration and enter the standby state. In this way, the beam search is performed first, the resident frequency point is determined, and then registration is performed, so as to realize the network access of the low-orbit narrowband satellite terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A hardware structure block diagram of a low-orbit narrowband vehicle-mounted terminal provided in an embodiment of the present invention.

[0019] Figure 2 A schematic diagram of the composition structure of an application processing unit provided in an embodiment of the present invention.

[0020] Figure 3 A schematic diagram of a software layered architecture of a baseband processing unit provided in an embodiment of the present invention.

[0021] Figure 4 A schematic diagram of a software platform architecture of a baseband processing unit provided in an embodiment of the present invention.

[0022] Figure 5A schematic diagram of a DSP-side platform architecture of a baseband processing unit provided in an embodiment of the present invention.

[0023] Figure 6 A schematic diagram of the working process of a low-orbit narrowband satellite terminal after startup provided by an embodiment of the present invention.

[0024] Figure 7 A schematic diagram of a process flow of a terminal network access method provided by an embodiment of the present invention.

[0025] Figure 8 A schematic diagram of the structure of a terminal network access device provided by an embodiment of the present invention.

[0026] Fig. 9 A schematic structural diagram of a low-orbit narrowband satellite terminal provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0030] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0031] Here, some keywords in the field of satellite communications involved in the present invention are first introduced:

[0032] 1. Carrier: The carrier is an electromagnetic wave with a specific frequency emitted by the satellite. Voice, data or video can be loaded onto the carrier for transmission through signal modulation.

[0033] 2. Carrier frequency: The frequency point is the carrier frequency point, which uniquely identifies the frequency position of a specific communication channel.

[0034] 3. Beam and cell: A beam refers to the electromagnetic wave signal emitted from a satellite antenna, and a cell is the coverage area of ​​a beam. Electromagnetic wave signals can have different shapes, sizes, and directivities, which determine the size of the cell. A satellite can generate multiple beams, each covering a different ground area. Each beam may use a specific set of carriers, or multiple beams may share a set of carrier resources.

[0035] 4. Beam switching: When a satellite terminal moves, it may move from the coverage area of ​​one beam to the coverage area of ​​another beam. At this time, beam switching is required to ensure the continuity of communication.

[0036] 5. Burst: The data such as voice, data or video loaded onto the carrier through signal modulation is called burst.

[0037] 6. PMBCH (Physical Multicast Broadcast Channel): Physical multicast broadcast channel. Used to transmit multicast and broadcast services, such as video streaming, audio broadcast, etc.

[0038] 7. PFCCH (Physical Frequency Correlation Channel): Physical frequency correlation channel. Used to send information about downlink spectrum resource allocation to the UE.

[0039] 8. PBCCH (Physical Broadcast Control Channel): Physical broadcast control channel. Used to transmit system information related to broadcast services, such as cell identification, frequency configuration, etc.

[0040] 9. PRACH (Physical Random Access Channel): It is used by UE to send random access request to the network to establish the initial communication link.

[0041] 10. PAGCH (Physical Access Grant Channel): Physical access grant channel. Used by the network to send access grant to the UE, indicating when the UE can start transmitting data.

[0042] The present invention relates to a low-orbit narrowband satellite terminal. The functions, software and hardware structures, etc. of the low-orbit narrowband satellite terminal are first introduced below.

[0043] 1. Terminal functions:

[0044] (1) System: Supporting the low-orbit narrowband standard system;

[0045] (2) Services: support voice, SMS and data services;

[0046] (3) Duplex mode: FDD (Frequency Division Duplexing) full duplex;

[0047] (4) Positioning: Support Beidou navigation positioning;

[0048] (5) Security: with authentication and encryption and decryption functions;

[0049] (6) It has the function of satellite over-the-top tracking;

[0050] (7) It has the capability to automatically search for satellites and automatically access the system.

[0051] 2. Terminal hardware composition:

[0052] See also Figure 1 The low-orbit narrowband vehicle-mounted terminal includes hardware parts such as antenna, RF transceiver channel, baseband processing unit, application processing unit, and power management unit.

[0053] The main function of the antenna is to send and receive electromagnetic waves. The antenna uses the existing L-band phased array antenna.

[0054] The RF unit mainly includes up and down conversion, signal amplification and filtering. It is responsible for converting the satellite downlink signal through the downlink channel into a signal that can be used by the baseband, and converting the uplink signal transmitted by the baseband into a satellite signal and transmitting it through the antenna;

[0055] The baseband processing unit belongs to the satellite communication processing unit, which mainly realizes the functions of low-orbit satellite communication protocol processing, baseband signal modulation and demodulation, signal digital-to-analog conversion, radio frequency transceiver, authentication and confidentiality. In terms of hardware structure, the baseband processing unit mainly includes baseband processing chip, radio frequency transceiver chip, storage chip, power management chip and other peripheral circuits;

[0056] The application processing unit is mainly responsible for controlling and scheduling the entire system functions, ensuring that each module can work normally and running various terminal business functions. The composition of the application processing unit is as follows: Figure 2 shown.

[0057] 3. Terminal software architecture:

[0058] The software layered architecture of the baseband processing unit is as follows: Figure 3 As shown, it is mainly divided into two parts: protocol layer and physical layer.

[0059] 1. Protocol layer

[0060] The protocol layer mainly implements communication functions, including the non-access stratum (NAS), L3 layer (RRC, i.e.: Radio Resource Control), L2 layer (ADAP (Service Data Adaptation Protocol), PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control)) and physical layer (PHY). Their respective responsibilities are as follows:

[0061] 1. NAS layer:

[0062] The NAS layer implements the control plane and user plane functions of the non-access layer. The control plane mainly includes:

[0063] (1) Mobility Management Module (MM): Mainly responsible for: terminal registration and deregistration functions in the network; two-way authentication between the terminal and the network; terminal identity recognition; NAS security mode control and terminal service request in the network;

[0064] (2) Session Management Module (SM): implements the PDU session establishment, modification and release functions;

[0065] (3) User card module (USIM): realizes USIM card file reading and writing; USIM card related command operations, such as authentication function;

[0066] (4) Network selection module (PLMN): supports network selection at startup and after network loss; high priority network selection and manual network search function;

[0067] (5) AT command processing module (ATC): mainly responsible for AT command processing functions;

[0068] The user plane mainly includes the packet data domain management module (PDM): it is mainly responsible for the transmission of uplink user data, TFT filtering function and uplink data transmission flow control function; it is responsible for the reception of downlink user data and the generation of reflective QoS rules.

[0069] 2. L3 layer:

[0070] RRC is mainly responsible for functions such as system information reception, paging reception, RRC connection management, access layer security key management and mobility management, including:

[0071] (1) Cell Selection and Reselection Module (CSR): implements PLMN search function, supporting foreground search and background search; cell selection function, supporting Store Cell Selection and Initial Cell Selection; cell reselection function, to reside in a more suitable cell to obtain a better service experience;

[0072] (2) System Information Receiver (SIA): Obtain MIB and SIB1; Obtain OSI, supporting Broadcasting and On-Demand acquisition methods;

[0073] (3) Connection Control Module (RCE): responsible for paging processing; implements RRC connection establishment, connection reestablishment and connection recovery functions, RRC reconfiguration functions, access layer security functions, RRC connection release functions and radio link failure processing;

[0074] (4) Measurement Control Reporting Module (MCR): implements measurement configuration function; implements measurement reporting and CGI measurement functions.

[0075] 3. L2 layer:

[0076] Mainly responsible for data access control and transmission functions, including:

[0077] (1) Media Access Control Module (MAC): Mainly responsible for the mapping of logical channels to transport channels, logical channel priority management, multiplexing and demultiplexing, random access control, HARQ (Hybrid Automatic Repeat Request) error correction and scheduling information reporting;

[0078] (2) Radio Link Control Module (RLC): Mainly responsible for fragmentation and reassembly, ARQ (Automatic Repeat Request) error correction, duplicate packet detection, etc.

[0079] (3) Packet Data Convergence Protocol (PDCP): mainly responsible for IP header compression and decompression, reordering and duplicate detection, encryption and decryption and integrity protection, protocol data routing and retransmission, etc.

[0080] (4) Service Data Adaptation Protocol (SDAP) module: mainly responsible for the mapping function between QoS (Quality of Service) flow and DRB (Data Radio Bearer).

[0081] 2. Physical Layer

[0082] The physical layer trigger period changes with the subcarrier spacing configuration parameters, and provides services to the MAC layer in the form of a transmission channel. It is responsible for a series of functions such as physical layer HARQ processing, modulation coding, multi-antenna processing, signal to physical time-frequency resource mapping, and control of transmission channel to physical channel mapping. Among them, the software platform architecture of the baseband processing unit is as follows: Figure 4 As shown, combined Figure 4 It can be seen that the baseband processing unit mainly uses SoC (System on Chip) processor, so its DSP software platform includes: DSP platform, CP ARM platform, and AP ARM platform.

[0083] 1. DSP platform:

[0084] Provides underlying operating system, RF and peripheral drivers, and general algorithm library. DSP side platform architecture such as Figure 5 As shown, combined Figure 5 It can be seen that the DSP platform includes the following parts:

[0085] (1) Operating System Abstraction Layer (OAL): Mainly responsible for the configuration of the physical layer software operating environment and providing the basic necessary OS support for the operation of the protocol layer software;

[0086] (2) Driver (DD): Mainly responsible for the physical layer related peripheral device driver and software and hardware interface processing, such as the configuration, enabling and disabling of RFIC devices;

[0087] (3) Physical layer protocol master control (L1CC): completes the basic protocol process functions of the physical layer, such as signal acquisition, random access, physical layer measurement, fast control, etc.;

[0088] (4) Communication Algorithm Library (ALGO): Provides a partial physical layer digital signal processing algorithm library, which is refined into different algorithm modules according to different waveforms.

[0089] 2. CP ARM platform:

[0090] The CP ARM subsystem is divided into a platform subsystem, a driver subsystem, and an audio subsystem. The platform subsystem provides an operating support environment and a unified functional interface for protocol stack development and platform business capabilities. The driver subsystem encapsulates underlying peripherals and external channels, and provides an operating interface for the platform to access underlying peripherals. The audio subsystem completes the source encoding and decoding and voice enhancement processing functions in the voice communication process. This module runs on a dedicated DSP TL420. Figure 4 It can be seen that according to different functions, the CP ARM side software system is divided into 4 major modules:

[0091] (1) PA: Platform Adapter, platform adaptation layer, mainly including driver, BSP and other modules;

[0092] (2) PE: Platform Enabler, platform capability layer, mainly including OS kernel, mux, etc., is the core of the CP ARM side software platform; supports users to expand some common public components in this layer;

[0093] (3) PSE: Platform Service Enabler, platform service capability layer; provides basic service sub-modules. This layer is the main processing part for users to expand their own communication protocols;

[0094] (4) HLS: High-level protocol software subsystem. This module is developed by the user, and the platform provides a protocol software development framework.

[0095] The above is an introduction to the software and hardware structure of the low-orbit narrowband satellite terminal.

[0096] See also Figure 6 ,based on Figure 6 From the work flow after power-on of the low-orbit narrowband satellite terminal shown in the figure, it can be seen that the low-orbit narrowband satellite terminal has the functions of automatic satellite search and automatic access to the low-orbit satellite system of the star network. Satellite communication supports: voice, data Internet access, SMS service transmission, Beidou RNSS (Radio Navigation Satellite Service) positioning, authentication and encryption and decryption, etc. The main work flow includes power-on, initial synchronization, registration to the network, standby and service, etc.

[0097] exist Figure 6 Based on this, the terminal network access method provided by an embodiment of the present invention is introduced as follows.

[0098] Please refer to Figure 7 , Figure 7 A schematic flow chart of a method for accessing a terminal to a network provided by an embodiment of the present invention is provided. The execution subject of the method is the low-orbit narrowband satellite terminal introduced above. The method comprises the following steps S101 to S103:

[0099] S101. After power-on initialization, a main beam search is performed to determine a resident cell.

[0100] In this embodiment, when positioning is unavailable, main beam search can be performed based on a priori beam list; and when positioning is available, main beam search can be performed based on current positioning and a priori beam list.

[0101] S102: Obtain a frequency point list corresponding to the resident cell, and determine a resident frequency point from multiple frequency points in the frequency point list.

[0102] In this embodiment, the determined resident frequency point is the central frequency point corresponding to the PBCCH (Packet Broadcast Control Channel) carrier.

[0103] S103: Register and interact with the satellite core network based on the resident frequency point to complete the network registration and enter the standby state.

[0104] In this embodiment, registration interaction is performed with the satellite core network based on the resident frequency point, and thus the standby state (ie, idle mode or normal service mode) can be entered.

[0105] An embodiment of the present invention provides a terminal network access method, which is as follows: after power-on initialization, the low-orbit narrowband terminal performs a main beam search to determine the resident cell; obtains a frequency point list corresponding to the resident cell, and determines the resident frequency point from multiple frequency points in the frequency point list; and performs registration interaction with the satellite core network based on the resident frequency point to complete the network access registration and enter the standby state. In this way, the beam search is performed first, the resident frequency point is determined, and then registration is performed, thereby realizing the network access of the low-orbit narrowband satellite terminal.

[0106] In an optional implementation, when positioning is unavailable, a main beam search may be performed based on a priori beam list. Therefore, the sub-steps of step S101 above may include S101a to S101h.

[0107] S101a, after power-on initialization, obtain a priori beam list.

[0108] In this embodiment, the a priori beam list includes multiple beams and their central frequencies. The a priori beam list may be a PLMN list preset before leaving the factory, or may be formed by gradually updating the PLMN list preset before leaving the factory during continuous use by the user.

[0109] S101b. Use the first beam in the prior beam list as the pending beam.

[0110] Combination Figure 4 It can be seen that the hardware of the baseband processing unit is mainly divided into: ARM domain and DSP domain. The ARM domain is mainly responsible for high-level protocol processing, and the DSP domain is mainly responsible for communication baseband algorithm processing. The PMBCH function module running in the DSP domain determines the fast search strategy based on the prior beam list, and then searches the beams in the prior beam list according to the fast search strategy.

[0111] In this embodiment, the fast search strategy is to search one by one.

[0112] S101c. Setting parameters of a radio frequency transceiver channel based on a center frequency of the beam to be determined.

[0113] S101d. Receive the satellite downlink signal through the radio frequency transceiver channel, and filter and amplify the satellite downlink signal to obtain a signal data frame.

[0114] In this embodiment, the PMBCH function module sets the RF transceiver channel work task to the corresponding carrier frequency according to the center frequency of the beam to be determined. Thus, the satellite downlink signal can be received through the RF transceiver channel, and the intermediate frequency module filters and amplifies the satellite downlink signal and sends it to the synchronization capture module in units of data frames (i.e., signal data frames).

[0115] S101e, based on the signal data frame, capture and track the PFCCH burst on the PMBCH carrier to obtain synchronization state information, frequency synchronization information and time synchronization information;

[0116] In this embodiment, the PMBCH carrier is the information carrier of the signal data frame. The synchronization capture module running in the DSP domain captures and tracks the PFCCH burst on the PMBCH carrier (formed by modulating data onto the PMBCH carrier) to obtain synchronization state information, frequency synchronization information and time synchronization information.

[0117] S101f, based on the synchronization status information, determining whether there is a valid PMBCH carrier at the center frequency of the pending beam;

[0118] In this embodiment, the PMBCH function module determines whether there is a valid PMBCH carrier at the center frequency of the current pending beam based on the acquired synchronization status information. Among them, the satellite downlink signal belonging to the electromagnetic wave is an analog signal, which needs to be converted into a digital signal device to process and obtain information. Therefore, the valid PMBCH carrier refers to whether the satellite downlink signal can eventually be converted into a digital signal with a sufficiently clear waveform (the noise interference in the waveform is small enough).

[0119] If there is no valid PMBCH carrier at the center frequency of the pending beam, then execute the following step S101g and then return to execute the above step S101c until there is a valid PMBCH carrier at the center frequency of the pending beam. If there is a valid PMBCH carrier at the center frequency of the pending beam, then directly execute the following step S101h.

[0120] S101g: Use the next beam in the priori beam list as a new pending beam.

[0121] S101h, the cell corresponding to the pending beam is used as the resident cell, and frequency correction and timing correction are performed based on the frequency synchronization information and time synchronization information respectively.

[0122] In this embodiment, if a valid PMBCH carrier exists at the central frequency point of the pending beam, then the cell corresponding to the pending beam can be used as the resident cell, and under the premise of the pending beam, the frequency synchronization information and time synchronization information obtained by the synchronization capture module will be used for frequency correction and timing correction respectively to ensure that the absolute position of the physical frame can be determined (that is, to ensure that the absolute frequency point position of the physical burst block can be accurately determined).

[0123] In an optional implementation, when the positioning is available, the main beam search may be performed based on the current positioning and the prior beam list. Therefore, the sub-steps of the above step S101 may include S101A to S101D.

[0124] S101A, after power-on initialization, obtain current positioning, ephemeris information and a priori beam list.

[0125] In this embodiment, the current positioning is obtained by the baseband processing unit based on the positioning second signal sent by the Beidou module. Ephemeris information is a collection of satellite orbit parameters, which describes the position and time of the satellite in space. Ephemeris information is broadcast by satellite, so the low-orbit narrowband satellite terminal may receive multiple copies of ephemeris information.

[0126] S101B: Determine at least one candidate cell where the current location is located from the prior beam list based on the ephemeris information.

[0127] In this embodiment, the signal coverage area of ​​the satellite can be calculated based on the ephemeris information. If the current positioning is in the signal coverage area, all candidate cells in the signal coverage area are found from the prior beam list.

[0128] S101C: When the number of candidate cells is unique, use the candidate cells as resident cells.

[0129] S101D: When the number of candidate cells is not unique, select a candidate cell with the strongest signal quality from all candidate cells as the resident cell.

[0130] In this embodiment, the method of selecting the candidate cell with the strongest signal quality from all candidate cells as the resident cell can be: taking the beam corresponding to each candidate cell as the pending beam in turn, and executing the above steps S101c~S101h for each pending beam until the resident cell is determined.

[0131] Optionally, after determining the resident cell, the prior beam list needs to be updated: according to the relative positions of the frequency points corresponding to the PFCCH burst and the PMBCH burst on the broadcast channel, the PMBCH functional module parses the broadcast channel, obtains the PMBCH carrier information of each adjacent beam from the broadcast system information, and schedules the link measurement module to calculate the signal strength of each adjacent beam broadcast channel based on the PMBCH carrier information of each adjacent beam, and then selects the beam corresponding to the adjacent beam broadcast channel with the largest signal strength as a candidate beam, and adds the candidate beam to the prior beam list, so that beam reselection, PLMN selection and gateway selection can be performed based on the updated prior beam list.

[0132] In an optional implementation, in the above step S102, the frequency list may include frequencies of multiple PBCCH carriers. Therefore, in the above step S102, the process of determining the resident frequency from the multiple frequencies in the frequency list may include the following sub-steps S1021 to S1024.

[0133] S1021. For each frequency of the PBCCH carrier in the frequency list, set parameters for a radio frequency transceiver channel based on the frequency, so as to receive a satellite downlink signal through the radio frequency transceiver channel.

[0134] S1023: Determine the signal strength of the satellite downlink signal, obtain a PBCCH burst on the PBCCH carrier based on the satellite downlink signal, and then parse the PBCCH burst to obtain LAI information, access restriction information, and load information.

[0135] In this embodiment, the LAI information is location area identity information, which is used to reflect: the country where the device is located, the network operator where the device is located, and the network operator where the device is located.

[0136] S1024. Based on the signal strength of the received satellite downlink signal corresponding to the frequency of each PBCCH carrier, the LAI information, access restriction information and load information obtained by parsing, and the preset priority list, the best PBCCH carrier is selected from multiple frequency points in the frequency point list, and the frequency point of the best PBCCH carrier is used as the resident frequency point.

[0137] In this embodiment, based on the signal strength of the received satellite downlink signal corresponding to the frequency of each PBCCH carrier, the parsed LAI information, access restriction information and load information, and the preset priority list, the best PBCCH carrier can be comprehensively selected from multiple frequency points in the frequency point list.

[0138] In an optional implementation, in the above step S103, the process of performing registration interaction with the satellite core network based on the resident frequency point to complete the network registration and enter the standby state may include the following sub-steps S1031~S1035.

[0139] S1031. Periodically receive a satellite downlink signal based on the resident frequency point to obtain frequency correction information and time correction information, and parse PBCCH burst data obtained from the satellite downlink signal to obtain system information.

[0140] In this embodiment, after determining the resident cell and resident frequency, the physical layer function module periodically schedules the synchronization capture module to obtain frequency correction information and time correction information, and at the same time sends the received PBCCH burst data to the upper layer protocol software module running in the ARM domain through the inter-core communication mechanism, and the RRC parses the data to obtain sufficient system information so that the NAS layer protocol function module can then initiate a location update (registration) process to complete the registration and network access.

[0141] S1032. Determine configuration parameter information for initial access based on the current positioning and random access channel information, system time synchronization information, frequency correction information, satellite position, beam center position, and current position in the system information.

[0142] In this embodiment, the RRC protocol entity running in the ARM domain forms the configuration parameter information for initial access based on the random access channel information, system time synchronization information, frequency correction information, satellite position, beam center position and current position in the system information obtained in step S1031.

[0143] S1033: Generate a random access request.

[0144] In this embodiment, the RRC protocol entity also generates a random access request, and then sends the random access request and configuration parameter information to the MAC layer protocol entity.

[0145] S1034. Based on the configuration parameter information, encode, symbol map, modulate, and filter the random access request in sequence to obtain a physical burst block, and send the physical burst block to the satellite core network.

[0146] In this embodiment, the MAC layer protocol entity implements random access scheduling: the physical layer protocol entity running in the DSP domain is scheduled and configured according to the configuration parameter information, so that the physical layer protocol entity encodes, symbol maps, modulates, and filters the random access request according to the logical channel type to form a physical burst block, and configures the hardware function module according to the scheduling parameters such as time and frequency to send the physical burst block to the satellite core network.

[0147] S1035. When a PAGCH burst is received at a fixed position on the downlink carrier, after parsing the PAGCH burst to obtain a response message from the satellite core network, a registration message is sent to the satellite core network to complete the network registration and enter the standby state; the registration message includes the identity information and location information of the low-orbit narrowband satellite terminal.

[0148] In this embodiment, after completing the transmission of the physical burst block, the physical layer protocol entity will schedule the reception of the PAGCH burst at the fixed position of the corresponding downlink carrier and wait for the response of the network. After receiving the physical burst block and parsing the random access request, the satellite core network will allocate uplink and downlink resources to the low-orbit narrowband satellite terminal and then send a response message to the connection request.

[0149] Therefore, after the low-orbit narrowband satellite terminal confirms receipt of the response message from the satellite core network, it indicates that the access layer connection has been established. Then, the NAS layer protocol entity will use the wireless bearer established by the access layer to send a registration message to the satellite core network, execute the NAS layer registration process, and complete the registration. After registration, depending on the network side configuration, circuit and packet domain attachment can be performed separately, or a joint attachment process can be performed.

[0150] Optionally, after the registration process is completed, the system of the low-orbit narrowband satellite terminal enters the standby mode. In the standby mode, the physical layer protocol entity will periodically perform position determination, beam reselection, broadcast channel reception scheduling, and schedule the reception of paging channel bursts on a fixed resident carrier and time according to the determined common control channel and paging group. The upper layer protocol entity will perform the position update process according to the determined location information, update the system information according to the broadcast channel bursts received by the scheduling, and monitor the paging message according to the paging channel bursts received by the scheduling.

[0151] In idle mode, the upper layer protocol entity will also periodically initiate cell update, GRA update and other protocol processes to keep information synchronized with the network. According to the characteristics of idle mode, the system will enter low power mode, shut down unnecessary hardware modules, reduce operating frequency, and minimize power consumption.

[0152] In idle mode, the low-orbit narrowband satellite terminal can provide call services and / or data Internet services.

[0153] Therefore, in the case of providing circuit domain services, namely voice services, when the low-orbit narrowband satellite terminal is calling, the method may further include the following steps S201 and S203; or, when the low-orbit narrowband satellite terminal is called, the method may further include the following steps S202 and S203.

[0154] S201. In response to a user's call operation, a call request is generated and sent to a satellite core network, so that the satellite core network sends the call request to a calling terminal, and establishes a two-way dedicated channel from a low-orbit narrowband satellite terminal to the calling terminal when it is determined that the calling terminal responds to the call request.

[0155] In this embodiment, when the low-orbit narrowband satellite terminal makes a call, it will actively initiate a connection establishment request with the satellite core network. Among them, the NAS layer protocol entity will execute the call process with the assistance of the AS layer protocol entity: generate a call request and send the call request to the satellite core network. After receiving the call request, the satellite core network will first exchange security information (identity authentication information and key information) with the upper layer protocol entity, and establish a connection with the core network domain. At the same time, it will configure the wireless access bearer of the circuit domain, associate the access layer wireless bearer, allocate wireless channel resources, and establish a two-way dedicated channel to carry voice services.

[0156] S202, receiving a call request sent by the calling terminal through the satellite core network, and when sensing the user's call receiving operation, sending a call response to the satellite core network, so that the satellite core network establishes a two-way dedicated channel from the low-orbit narrowband satellite terminal to the calling terminal.

[0157] In this embodiment, when a low-orbit narrowband satellite terminal is called, it can receive a call request forwarded by the satellite core network. Among them, the NAS layer protocol entity will execute the called call process with the assistance of the AS layer protocol entity: send a call response to the satellite core network. After receiving the call response, the satellite core network will first exchange security information (identity authentication information and key information) with the upper layer protocol entity, and establish a connection with the core network domain. At the same time, it will configure the wireless access bearer of the circuit domain, associate the access layer wireless bearer, allocate wireless channel resources, and establish a two-way dedicated channel to carry voice services.

[0158] S202: Perform voice interaction with the calling terminal based on the two-way dedicated channel, and when sensing the user's hang-up operation, send a hang-up request to the satellite core network to enable the satellite core network to release the two-way dedicated channel.

[0159] In this embodiment, after the low-orbit narrowband satellite terminal makes a call or is called, it will perform voice interaction with another calling terminal.

[0160] Optionally, the process of performing voice interaction with the calling terminal based on the two-way dedicated channel may include the following sub-steps S2021-S2022:

[0161] S2021. When the user's voice signal is obtained, the voice signal is sequentially subjected to digital-to-analog conversion, detection, noise elimination, enhancement, compression and coding and decoding to obtain local voice data; and, according to the logical channel type mapped by the radio bearer, the local voice data is encrypted and assembled into the local RLC / MAC data block and then encapsulated into the local logical channel burst data; and, the local logical channel burst data is sequentially subjected to data encoding or multiplexing, channel coding, symbol mapping, modulation, and filtering and shaping to form the local physical burst block, and the local physical burst block is sent to the calling terminal through a bidirectional dedicated channel;

[0162] During a call, the software and hardware components of the voice signal processing module will work together to complete the functions of digital-to-analog conversion, detection, noise reduction, enhancement, compression and decoding of voice signals. The local voice data is transparently transmitted to the MAC protocol entity through the RLC entity associated with the corresponding radio bearer. At the MAC layer, the protocol entity encrypts the local voice data and forms the local RLC / MAC data block according to the logical channel type mapped by the radio bearer, encapsulates the local logical channel burst, and waits for scheduling.

[0163] According to the scheduling time granularity of frame / time slot, the logical channel burst block of the local end waiting for scheduling is transferred from the ARM domain to the DSP domain through the inter-core communication mechanism inside the chip and handed over to the physical layer protocol entity. The physical layer will complete data encoding or multiplexing, channel coding, symbol mapping, modulation, and filtering according to the requirements of the scheduling configuration to form the local physical burst block, which is pushed to the RF front end under the baseband timing control logic.

[0164] S2022. When receiving a physical burst block of the opposite end sent by the calling terminal through a bidirectional dedicated channel, the physical burst block of the opposite end is filtered, demodulated, symbol mapped, channel decoded, data decoded or multiplexed in sequence to obtain the logical channel burst data of the opposite end; and, the logical channel burst data of the opposite end is decapsulated to obtain the RLC / MAC data block of the opposite end, and then decrypted to obtain the voice data of the opposite end; and, the voice data of the opposite end is decompressed, encoded, decoded, enhanced, denoised, detected, and digital-to-analog converted in sequence to obtain the voice signal of the opposite end, and the voice signal of the opposite end is played.

[0165] In this embodiment, the reception of voice data is the reverse process of the transmission, and the voice data carried by a specific logical channel is channel-decoded using a turbo decoder unit.

[0166] When the packet domain service provided is a data Internet access service, the method may further include the following steps S301 to S303:

[0167] S301. When there is a need to access the Internet, a resource request is sent to the satellite core network, so that the satellite core network allocates resources based on the resource request and establishes a bidirectional data channel from the terminal to the satellite core network;

[0168] In this embodiment, when there is a demand for Internet access at the application layer (such as a web browser, email client, etc.), the service demand for packet data is sent to the NAS layer through the application layer entity, triggering the NAS layer protocol entity to execute the data service process: sending a resource request to the satellite core network.

[0169] S302: Receive a resource response sent by the satellite core network.

[0170] In this embodiment, the resource response includes the PDCP entity and RLC entity assigned by the satellite core network and uplink resources.

[0171] Among them, after receiving the resource request, the satellite core network will first exchange security information (identity authentication information and key information) with the upper-layer protocol entity, and establish a connection with the core network domain. At the same time, it will configure the wireless access bearer of the packet domain (the bearer satellite in the core network), associate the access layer wireless bearer, assign the corresponding type of PDCP entity and RLC entity, allocate wireless channel resources, establish an effective two-way data channel, and realize the connection of the control plane.

[0172] S303: Based on the PDCP entity, the RLC entity and the uplink resources, the packet data is sent through a bidirectional data channel.

[0173] After the control plane connection is completed, the packet data (i.e., Internet access data) will be transmitted to the RLC / MAC protocol sublayer through the PDCP sublayer. The RLC / MAC protocol entity dynamically applies for uplink resources from the satellite core network based on the service data transmission requirements. The satellite core network dynamically specifies the uplink resources of the wireless bearer based on the application requirements, combined with parameters such as terminal type and wireless priority. The RLC / MAC entity schedules the related logical channel bursts according to the allocated uplink resources to carry the packet data.

[0174] Optionally, when executing circuit domain services or packet domain services, the link correction process is executed: the satellite core network estimates link correction information such as power, frequency, and time based on the received uplink burst, and sends the correction message to the low-orbit narrowband satellite terminal through the associated control channel.

[0175] After the control message received by the low-orbit narrowband satellite terminal through the control channel is parsed by the RRC or RLC / MAC layer protocol entity, the correction information obtained is sent down to the frequency-time-power correction module of the physical layer to control the frequency, time and power of burst transmission.

[0176] Optionally, when executing circuit domain services or packet domain services, the low-orbit narrowband satellite terminal will also regularly report location information, link quality information, and signal strength information of neighboring cells to the satellite core network to help the satellite core network decide the timing of cell switching (also called beam switching). Among them, the cell switching is initiated by the satellite core network, executing the radio bearer reconfiguration process of the RRC layer or the packet cell switching command process of the MAC layer. The satellite core network sends a cell switching instruction to the low-orbit narrowband satellite terminal based on the synchronization status of the low-orbit narrowband satellite terminal, and sends the new cell and its resource information as well as the link pre-correction information. Thereby, the upper-layer protocol entity completes the access to the new cell based on the link pre-correction information and the new cell and its resource information to keep the service transmission uninterrupted.

[0177] In order to execute the corresponding steps in the above method embodiment and various possible implementation modes, an implementation mode of a terminal network access device is provided below.

[0178] See also Figure 8 , Figure 8 The schematic diagram of the structure of the terminal network access device provided by the embodiment of the present invention is shown. The terminal network access device 200 is applied to a low-orbit narrowband satellite terminal, and the terminal network access device 200 includes: a beam search module 210 and a registration module 220.

[0179] The beam search module 210 is used to perform a main beam search to determine a resident cell after power-on initialization;

[0180] The beam search module 210 is used to obtain a frequency point list corresponding to the resident cell and determine the resident frequency point from multiple frequency points in the frequency point list;

[0181] The registration module 220 is used to perform registration interaction with the satellite core network based on the resident frequency point to complete the network registration and enter the standby state.

[0182] Optionally, the terminal network access device 200 may further include a call module 230 and a data Internet access module 240. The beam search module 210 may be used to implement the above steps S101, S102 and their respective sub-steps, the registration module 220 may be used to implement the above step S103 and its sub-steps, the call module 230 may be used to implement the above steps S201~S203 and their sub-steps, and the data Internet access module 240 may be used to implement the above steps S301~S303.

[0183] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the terminal access device 200 described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0184] See also Fig. 9 , Fig. 9 The schematic diagram of the structure of a low-orbit narrowband satellite terminal provided by an embodiment of the present invention is as follows: The low-orbit narrowband satellite terminal 300 includes a processor 310 , a memory 320 and a bus 330 , and the processor 310 is connected to the memory 320 via the bus 330 .

[0185] The memory 320 may be used to store software programs, for example, software programs corresponding to the terminal network access device 200 provided in the embodiment of the present invention. The processor 310 executes various functional applications and data processing to implement the terminal network access method provided in the embodiment of the present invention by running the software programs stored in the memory 320.

[0186] Among them, the memory 320 can be but is not limited to: RAM (Random Access Memory), ROM (Read Only Memory), FLASH (Flash Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electric Erasable Programmable Read-Only Memory), etc.

[0187] The processor 310 may be an integrated circuit chip with signal processing capability. The processor 310 may be a general-purpose processor, including: CPU (Central Processing Unit), NP (Network Processor), etc.; it may also be: DSP (Digital Signal Processing), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0188] Understandably, Fig. 9 The structure shown is for illustration only. The low-orbit narrowband satellite terminal 300 may also include Fig. 9 More or fewer components as shown, or with Fig. 9 Different configurations are shown. Fig. 9 Each component shown in the figure can be implemented by hardware, software or a combination thereof.

[0189] The embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the terminal network access method disclosed in the above embodiment is implemented. The computer-readable storage medium can be, but is not limited to, various media that can store program codes, such as a USB flash drive, a mobile hard disk, a ROM, a RAM, a PROM, an EPROM, an EEPROM, a FLASH disk, or an optical disk.

[0190] In summary, the embodiments of the present invention provide a terminal network access method, device, low-orbit narrowband satellite terminal and readable storage medium. The method is: after power-on initialization, perform main beam search to determine the resident cell; obtain the frequency point list corresponding to the resident cell, and determine the resident frequency point from multiple frequency points in the frequency point list; register and interact with the satellite core network based on the resident frequency point to complete the network access registration and enter the standby state. In this way, the beam search is performed first, the resident frequency point is determined, and then registration is performed, so as to realize the network access of the low-orbit narrowband satellite terminal.

[0191] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for terminal accessing a network, characterized in that: Applied to a low-orbit narrowband satellite terminal, the low-orbit narrowband satellite terminal includes a radio frequency transceiver channel; the method includes: After power-on initialization, a main beam search is performed to determine the resident cell; Acquire a frequency point list corresponding to the resident cell, and determine a resident frequency point from multiple frequency points in the frequency point list; Performing registration interaction with the satellite core network based on the resident frequency point to complete network registration and enter a standby state; The frequency point list includes frequency points of multiple PBCCH carriers; the step of determining a resident frequency point from the multiple frequency points in the frequency point list includes: For each frequency of the PBCCH carrier in the frequency list, setting parameters of the radio frequency transceiver channel based on the frequency, so as to receive a satellite downlink signal through the radio frequency transceiver channel; Determine the signal strength of the satellite downlink signal, and after obtaining a PBCCH burst on a PBCCH carrier based on the satellite downlink signal, parse the PBCCH burst to obtain LAI information, access restriction information and load information; Based on the signal strength of the received satellite downlink signal corresponding to the frequency of each PBCCH carrier, the LAI information, access restriction information and load information obtained by analysis, and a preset priority list, the best PBCCH carrier is selected from multiple frequency points in the frequency point list, and the frequency point of the best PBCCH carrier is used as the resident frequency point.

2. The method according to claim 1, characterized in that: The step of performing a main beam search to determine a resident cell after power-on initialization includes: After power-on initialization, obtain a priori beam list, the priori beam list including multiple beams and their center frequencies; Taking the first beam in the prior beam list as the pending beam; Setting parameters of the radio frequency transceiver channel based on the center frequency of the beam to be determined; Receiving a satellite downlink signal through the radio frequency transceiver channel, and filtering and amplifying the satellite downlink signal to obtain a signal data frame; Based on the signal data frame, the PFCCH burst on the PMBCH carrier is captured and tracked to obtain synchronization state information, frequency synchronization information and time synchronization information; the PMBCH carrier is the information carrier of the signal data frame; Based on the synchronization status information, determining whether there is a valid PMBCH carrier at the center frequency of the pending beam; If so, the cell corresponding to the pending beam is used as the resident cell, and frequency correction and timing correction are performed based on the frequency synchronization information and the time synchronization information respectively; If it does not exist, the next beam in the prior beam list is used as the new pending beam, and the step of setting the parameters of the RF transceiver channel based on the center frequency of the pending beam is returned to execute until there is a valid PMBCH carrier at the center frequency of the pending beam.

3. The method according to claim 1, characterized in that: The step of performing a main beam search to determine a resident cell after power-on initialization includes: After power-on initialization, obtain the current positioning, ephemeris information and a priori beam list, the priori beam list includes multiple beams and their center frequencies; Determine at least one candidate cell where the current location is located from the prior beam list based on the ephemeris information; When the number of the candidate cells is unique, taking the candidate cells as the resident cells; When the number of the candidate cells is not unique, a beam corresponding to the first candidate cell among all the candidate cells is used as a pending beam; Setting parameters of the radio frequency transceiver channel based on the center frequency of the beam to be determined; Receiving a satellite downlink signal through the radio frequency transceiver channel, and filtering and amplifying the satellite downlink signal to obtain a signal data frame; Based on the signal data frame, the PFCCH burst on the PMBCH carrier is captured and tracked to obtain synchronization state information, frequency synchronization information and time synchronization information; the PMBCH carrier is the information carrier of the signal data frame; Based on the synchronization status information, determining whether there is a valid PMBCH carrier at the center frequency of the pending beam; If so, the cell corresponding to the pending beam is used as the resident cell, and frequency correction and timing correction are performed based on the frequency synchronization information and the time synchronization information respectively; If it does not exist, the beam corresponding to the next candidate cell will be used as the new pending beam, and the step of setting the parameters of the RF transceiver channel based on the center frequency of the pending beam will be returned to until there is a valid PMBCH carrier at the center frequency of the pending beam.

4. The method according to claim 1, characterized in that: The step of registering and interacting with the satellite core network based on the resident frequency point to complete network registration and enter the standby state includes: Based on the resident frequency point, a satellite downlink signal is periodically received to obtain frequency correction information and time correction information, and PBCCH burst data obtained from the satellite downlink signal is analyzed to obtain system information; Determine configuration parameter information for initial access based on the current positioning and random access channel information, system time synchronization information, frequency correction information, satellite position, beam center position, and current position in the system information; generating a random access request; Based on the configuration parameter information, the random access request is encoded, symbol mapped, modulated, and filtered in sequence to obtain a physical burst block, and the physical burst block is sent to a satellite core network; When a PAGCH burst is received at a fixed position on the downlink carrier, after parsing the PAGCH burst to obtain a response message from the satellite core network, a registration message is sent to the satellite core network to complete the network registration and enter the standby state; the registration message includes the identity information and location information of the low-orbit narrowband satellite terminal.

5. The method according to claim 1, characterized in that The method further comprises: In response to a user's calling operation, generating a calling request and sending the calling request to a satellite core network, so that the satellite core network sends the calling request to a calling terminal, and establishing a two-way dedicated channel from the low-orbit narrowband satellite terminal to the calling terminal when it is determined that the calling terminal responds to the calling request; Alternatively, receiving a call request sent by the calling terminal through the satellite core network, and when sensing a call receiving operation of the user, sending a call response to the satellite core network, so that the satellite core network establishes a two-way dedicated channel from the low-orbit narrowband satellite terminal to the calling terminal; The method comprises performing voice interaction with the calling terminal based on the two-way dedicated channel and sending a hang-up request to the satellite core network when sensing a hang-up operation of the user, so that the satellite core network releases the two-way dedicated channel.

6. The method according to claim 5, characterized in that The step of performing voice interaction with the calling terminal based on the two-way dedicated channel includes: When the user's voice signal is obtained, the voice signal is sequentially subjected to digital-to-analog conversion, detection, noise elimination, enhancement, compression and coding and decoding to obtain the local voice data; and, according to the logical channel type mapped by the wireless bearer, the local voice data is encrypted and formed into the RLC / MAC data block of the local end and then encapsulated into the logical channel burst data of the local end; and, the logical channel burst data of the local end is sequentially subjected to data encoding or multiplexing, channel coding, symbol mapping, modulation, and filtering and shaping to form the local physical burst block, and the local physical burst block is sent to the calling terminal through the bidirectional dedicated channel; When receiving the opposite end physical burst block sent by the calling terminal through the bidirectional dedicated channel, the opposite end physical burst block is filtered, demodulated, symbol mapped, channel decoded, data decoded or multiplexed in sequence to obtain the opposite end logical channel burst data; and the opposite end logical channel burst data is decapsulated to obtain the opposite end RLC / MAC data block and then decrypted to obtain the opposite end voice data; and the opposite end voice data is decompressed, encoded, decoded, enhanced, denoised, detected, and digital-to-analog converted in sequence to obtain the opposite end voice signal, and the opposite end voice signal is played.

7. The method according to claim 1, characterized in that The method further comprises: When there is a need to access the Internet, a resource request is sent to the satellite core network, so that the satellite core network allocates resources based on the resource request and establishes a bidirectional data channel from the terminal to the satellite core network; Receiving a resource response sent by the satellite core network; the resource response includes a PDCP entity and an RLC entity and uplink resources assigned by the satellite core network; Based on the PDCP entity and the RLC entity and uplink resources, the packet data is sent through the bidirectional data channel.

8. A terminal network access device, characterized in that: Applicable to a low-orbit narrowband satellite terminal, the low-orbit narrowband satellite terminal includes a radio frequency transceiver channel; the device includes: A beam search module, used to perform a main beam search to determine a resident cell after power-on initialization; The beam search module is used to obtain a frequency point list corresponding to the resident cell, and determine a resident frequency point from multiple frequency points in the frequency point list; A registration module, used for registering and interacting with the satellite core network based on the resident frequency point to complete the network registration and enter the standby state; The frequency point list includes frequency points of multiple PBCCH carriers; when the beam search module is used to determine the resident frequency point from the multiple frequency points in the frequency point list, it is specifically used to: For each frequency of the PBCCH carrier in the frequency list, setting parameters of the radio frequency transceiver channel based on the frequency, so as to receive a satellite downlink signal through the radio frequency transceiver channel; Determine the signal strength of the satellite downlink signal, and after obtaining a PBCCH burst on a PBCCH carrier based on the satellite downlink signal, parse the PBCCH burst to obtain LAI information, access restriction information and load information; Based on the signal strength of the received satellite downlink signal corresponding to the frequency of each PBCCH carrier, the LAI information, access restriction information and load information obtained by analysis, and a preset priority list, the best PBCCH carrier is selected from multiple frequency points in the frequency point list, and the frequency point of the best PBCCH carrier is used as the resident frequency point.

9. A low-orbit narrowband satellite terminal, characterized in that: include: A memory and a processor, wherein the memory stores a software program, and when the low-orbit narrowband satellite terminal is running, the processor executes the software program to implement the terminal network access method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the terminal network access method according to any one of claims 1 to 7 is implemented.

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