Satellite terminal access control method and device, satellite terminal access method and device

Abstract

The application provides a satellite terminal access control method and device, and a satellite terminal access method and device. The control method comprises: grouping satellite terminals based on the previous positions and access periods of the satellite terminals; periodically waking up the satellite terminals in each group to send access probes in the wake-up window corresponding to the group; and after successfully detecting an access probe of any satellite terminal, authorizing the satellite terminal to send data to a satellite. The technical solution of the application groups satellite terminals based on terminal behaviors of the satellite terminals, combines space-time pre-shunting and a two-step access mechanism, significantly reduces the collision probability of random access of a large number of terminals and terminal power consumption, and improves system throughput.

Description

Technical Field

[0001] This application relates to the field of satellite communication technology, and in particular to a satellite terminal access control method and apparatus, and a satellite terminal access method and apparatus. Background Technology

[0002] With the rapid development of satellite IoT, tens of thousands of low-power, low-data-rate sensor terminals need to report data intermittently via satellite.

[0003] Traditional random access protocols, such as pure ALOHA or its improved versions, face severe challenges in scenarios with a large number of terminals: a large number of terminals simultaneously attempt to access a limited number of satellite channels in an unknown state, resulting in an extremely high collision probability (close to 100%) and low system throughput (typically below 0.37). At the same time, terminals have long radio frequency active times and huge power consumption in order to listen for global wake-up signals and perform long packet retransmissions, making it difficult to meet the requirements of long-term unattended operation.

[0004] Therefore, existing technologies lack the ability to utilize the behavioral patterns of terminals and cannot balance the contradiction between system access capabilities and terminal power consumption. Summary of the Invention

[0005] In view of this, embodiments of this application provide a satellite terminal access control method and apparatus, and a satellite terminal access method and apparatus. The technical solution of this application embodiment groups satellite terminals based on the terminal behavior of satellite terminals, and combines spatiotemporal pre-diversion and two-step access mechanism to significantly reduce the collision probability and terminal power consumption of massive random terminal access, and improve system throughput.

[0006] In a first aspect, embodiments of this application provide a satellite terminal access control method, comprising: grouping satellite terminals based on their previous positions and access cycles; periodically waking up each satellite terminal in a group to send an access probe within the wake-up window corresponding to that group; and authorizing the satellite terminal to send data to the satellite after successfully detecting the access probe of any satellite terminal.

[0007] Based on the terminal behavior of satellite terminals, satellite terminals are grouped, and combined with spatiotemporal pre-diversion and two-step access mechanisms, the collision probability and power consumption of massive random terminal access are significantly reduced, thereby improving system throughput.

[0008] In one possible implementation of the first aspect, the grouping of satellite terminals based on their previous location and access period includes: for a service area that a satellite arrives at after a set time, grouping the accessing satellite terminals according to the previous access period and location of each satellite terminal in the service area.

[0009] As described above, satellite terminals in close proximity enable satellites to communicate with the same group of satellite terminals using the same channel estimation parameters (including parameters to eliminate Doppler frequency offset), thereby improving communication speed. Grouping satellite terminals with similar access periods together ensures that the data readiness of satellite terminals in the same group is almost identical, and each satellite terminal has data to transmit upon wake-up, thus improving the utilization rate of communication channels.

[0010] In one possible implementation of the first aspect, the satellite terminals accessing the service area are grouped according to their previous access cycles and locations, including: in a three-dimensional space with access cycle, longitude, and latitude as dimensions, the satellite terminals in the service area are grouped by a clustering method according to their previous access cycles, longitude, and latitude.

[0011] Based on the three-dimensional feature vector of satellite terminal behavior constructed with access period, longitude and latitude as dimensions, the dynamic grouping of satellite terminals can be accurately achieved through clustering methods.

[0012] In one possible implementation of the first aspect, periodically waking up each satellite terminal within a group to send an access probe within the wake-up window corresponding to that group includes: for each satellite terminal within a group, periodically broadcasting a wake-up beacon for that group on the broadcast channel, wherein the wake-up beacon for each group includes the wake-up window of the satellite terminal in that group and the access channel that can be occupied.

[0013] Therefore, wake-up beacons for each group are periodically transmitted through the broadcast channel, so that each group's satellite terminals can receive their own wake-up beacons.

[0014] In one possible implementation of the first aspect, the access probe of each satellite terminal includes a common autocorrelation access pilot sequence and the ID of the satellite terminal; detecting the access probe of the satellite terminal includes: detecting the access signal power in each access time slot in the wake-up window of each group of satellite terminals on any access channel of the satellite; when the power exceeds a set power threshold, performing a sliding correlation between the access signal of the access time slot and the access pilot sequence; when only one correlation peak is detected, resolving the ID of the first satellite terminal from the access signal based on the position of the correlation peak.

[0015] Therefore, by including a common autocorrelation access pilot sequence and the satellite terminal's ID in the access probe of each satellite terminal, the satellite can facilitate collision detection and arbitration of the access probe.

[0016] In one possible implementation of the first aspect, the detection of the access probe of the satellite terminal further includes: when the sliding correlation detects more than one correlation peak, estimating a first access probe signal based on the position and intensity of the strongest correlation peak; when the ID of the second satellite terminal is parsed from the first access probe signal, subtracting the first access probe signal from the access signal to obtain a remaining signal; and continuing to perform sliding correlation between the remaining signal and the access pilot sequence to detect access probes of other second satellite terminals included in the remaining signal.

[0017] Therefore, in the access probe conflict scenario, separating the satellite terminal's access probe from the superimposed signal not only increases the authorization probability of the woken-up satellite terminal, but also reduces the number of times the satellite terminal accesses the network, thus reducing the access probe collision probability.

[0018] In one possible implementation of the first aspect, the control method further includes: broadcasting a message in the access response frame following the wake-up window authorizing the satellite terminal to send data with the ID parsed.

[0019] As described above, the access response frame following each wake-up window broadcasts a message authorizing the satellite terminal whose ID has been parsed to send data, ensuring that the authorized satellite terminal sends data in a timely manner.

[0020] In one possible implementation of the first aspect, the access response frame following the wake-up window also broadcasts one of the following messages: the backoff period N of the conflicting satellite terminal in the wake-up window and the conflict bitmap of the wake-up window.

[0021] As described above, the collision bitmap in the wake-up window enables the satellite terminal to know whether its access probe has collided, and thus enters hibernation according to the backoff command when a collision occurs.

[0022] Secondly, embodiments of this application provide a satellite terminal access method for a satellite terminal to access a satellite performing the method described in any of the embodiments of the first aspect, comprising: when the satellite terminal receives a wake-up message broadcast by the satellite, sending an access probe to the satellite; and when the satellite terminal receives a message broadcast by the satellite authorizing it to send data, sending data to the satellite.

[0023] As a result, by combining spatiotemporal pre-splitting and a two-step access mechanism, the collision probability and terminal power consumption of massive random terminal access are significantly reduced, thereby improving system throughput.

[0024] In one possible implementation of the second aspect, when the satellite terminal sends data to the satellite, it also sends the satellite terminal's access period and location.

[0025] As mentioned above, when sending data to the satellite, the satellite terminal also sends its access cycle and location, which facilitates the satellite side to group the satellites.

[0026] Thirdly, embodiments of this application provide a satellite terminal access control device, including: a grouping module, used to group satellite terminals based on their previous positions and access cycles; a wake-up module, used to periodically wake up each satellite terminal in the group to send an access probe within the wake-up window corresponding to the group; and an authorization module, used to authorize the satellite terminal to send data to the satellite after successfully detecting the access probe of any satellite terminal.

[0027] Based on the terminal behavior of satellite terminals, satellite terminals are grouped, and combined with spatiotemporal pre-diversion and two-step access mechanisms, the collision probability and power consumption of massive random terminal access are significantly reduced, thereby improving system throughput.

[0028] In one possible implementation of the third aspect, the grouping module is specifically used to group the accessing satellite terminals according to the previous access cycles and locations of each satellite terminal in the service area after the satellite arrives at the service area after a set time.

[0029] As described above, satellite terminals in close proximity enable satellites to communicate with the same group of satellite terminals using the same channel estimation parameters (including parameters to eliminate Doppler frequency offset), thereby improving communication speed. Grouping satellite terminals with similar access periods together ensures that the data readiness of satellite terminals in the same group is almost identical, and each satellite terminal has data to transmit upon wake-up, thus improving the utilization rate of communication channels.

[0030] In one possible implementation of the third aspect, when grouping the accessed satellite terminals according to their previous access cycles and locations in the service area, the grouping module is specifically used to group the satellite terminals in the service area using a clustering method in a three-dimensional space with access cycle, longitude, and latitude as dimensions.

[0031] Based on the three-dimensional feature vector of satellite terminal behavior constructed with access period, longitude and latitude as dimensions, the dynamic grouping of satellite terminals can be accurately achieved through clustering methods.

[0032] In one possible implementation of the third aspect, the wake-up module is used to broadcast a wake-up beacon for each satellite terminal in the group during the broadcast channel period. The wake-up beacon for each group includes the wake-up window of the satellite terminal in the group and the access channel that can be occupied.

[0033] Therefore, wake-up beacons for each group are periodically transmitted through the broadcast channel, so that each group's satellite terminals can receive their own wake-up beacons.

[0034] In one possible implementation of the third aspect, the access probe of each satellite terminal includes a common autocorrelation access pilot sequence and the ID of the satellite terminal; the control device further includes an arbitration module for detecting the access signal power in each access time slot of the wake-up window of each group of satellite terminals on any access channel of the satellite; when the power exceeds a set power threshold, performing a sliding correlation between the access signal of the access time slot and the access pilot sequence; when only one correlation peak is detected, resolving the ID of the first satellite terminal from the access signal based on the position of the correlation peak.

[0035] Therefore, by including a common autocorrelation access pilot sequence and the satellite terminal's ID in the access probe of each satellite terminal, the satellite can facilitate collision detection and arbitration of the access probe.

[0036] In one possible implementation of the third aspect, the arbitration module is further configured to estimate the first access probe signal based on the position and intensity of the strongest correlation peak when the sliding correlation detects more than one correlation peak; when the ID of the second satellite terminal is parsed from the first access probe signal, subtract the first access probe signal from the access signal to obtain the remaining signal; and continue to perform sliding correlation between the remaining signal and the access pilot sequence to detect the access probes of other second satellite terminals included in the remaining signal.

[0037] Therefore, in the access probe conflict scenario, separating the satellite terminal's access probe from the superimposed signal not only increases the authorization probability of the woken-up satellite terminal, but also reduces the number of times the satellite terminal accesses the network, thus reducing the access probe collision probability.

[0038] In one possible implementation of the third aspect, the authorization module is specifically used to broadcast a message in the access response frame following the wake-up window, authorizing the satellite terminal to send data with the ID parsed from the authorization.

[0039] As described above, the access response frame following each wake-up window broadcasts a message authorizing the satellite terminal whose ID has been parsed to send data, ensuring that the authorized satellite terminal sends data in a timely manner.

[0040] In one possible implementation of the third aspect, the authorization module is specifically configured to broadcast one of the following messages in the access response frame following the wake-up window: the backoff period N of the conflicting satellite terminal in the wake-up window and the conflict bitmap of the wake-up window.

[0041] As described above, the collision bitmap in the wake-up window enables the satellite terminal to know whether its access probe has collided, and thus enters hibernation according to the backoff command when a collision occurs.

[0042] Fourthly, embodiments of this application provide a satellite terminal access device for a satellite terminal to access a satellite performing the method described in any of the embodiments of the first aspect, comprising: an access module, configured to send an access probe to the satellite when the satellite terminal receives a wake-up message broadcast by the satellite; and a transmission module, configured to send data to the satellite when the satellite terminal receives a message broadcast by the satellite authorizing it to transmit data.

[0043] As a result, by combining spatiotemporal pre-splitting and a two-step access mechanism, the collision probability and power consumption of massive satellite terminals in random access are significantly reduced, thereby improving system throughput.

[0044] In one possible implementation of the fourth aspect, when the transmitting module sends data to the satellite, it is also used to transmit the access period and location of the satellite terminal.

[0045] As mentioned above, when sending data to the satellite, the satellite terminal also sends its access cycle and location, which facilitates the satellite side to group the satellites. Attached Figure Description

[0046] Figure 1 This is a schematic flowchart of the control method described in Embodiment 1 of this application;

[0047] Figure 2 This is a flowchart illustrating the access method described in Embodiment 2 of this application;

[0048] Figure 3 This is a flowchart illustrating the access method described in Embodiment 3 of this application;

[0049] Figure 4 This is a schematic diagram of satellite terminal access probe conflict in Embodiment 3 of this application;

[0050] Figure 5 This is a schematic diagram of the control device described in Embodiment 4 of this application;

[0051] Figure 6 This is a schematic diagram of the access device described in Embodiment 5 of this application. Detailed Implementation

[0052] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0053] In the following description, the terms “first, second, third, etc.” or module A, module B, module C, etc. are used not only to distinguish similar objects or different embodiments, but also do not represent a specific ordering of objects. It is understood that a specific order or sequence may be interchanged where permitted so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0054] In the following description, the labels of the steps, such as S110, S120, etc., do not necessarily mean that the steps will be executed in this way. The order of the steps can be interchanged or executed simultaneously if permitted.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0056] This application provides a satellite terminal access control method and apparatus, and a satellite terminal access method and apparatus. The control method operates on the satellite side and includes: grouping satellite terminals based on their previous positions and access cycles; periodically waking up each satellite terminal in the group to send an access probe within the corresponding wake-up window; and authorizing the satellite terminal to send data to the satellite after successfully detecting the access probe of any satellite terminal.

[0057] The technical solution of this application embodiment groups satellite terminals based on the terminal behavior of satellite terminals. Combined with spatiotemporal pre-diversion and two-step access mechanism, it significantly reduces the collision probability and terminal power consumption of random access of massive terminals and improves system throughput.

[0058] The embodiments of this application are described below with reference to the accompanying drawings. Figure 1 Example 1 of this application is described below.

[0059] Embodiment 1 of this application provides a satellite terminal access control method, which operates on a satellite. Figure 1 The process is shown, including steps S110 to S130.

[0060] S110: Group satellite terminals based on their previous location and access cycle.

[0061] The satellite terminal's previous location and access cycle are past behavioral characteristics of the satellite. Satellites are grouped based on these characteristics to group and wake up satellite terminals. Satellite terminals within the same group are located close to each other and have similar access cycles. In some embodiments, the satellite terminal is an Internet of Things (IoT) terminal with a small or even almost stationary movement range.

[0062] In this way, grouping not only reduces the probability of collisions between satellite terminals, but also allows satellites to communicate with a group of satellite terminals in close proximity using the same channel estimation parameters (including parameters to eliminate Doppler frequency offset), thereby improving the communication rate between the satellite and the group of terminals.

[0063] Satellite terminals with similar access cycles are grouped together, which ensures that the data readiness of satellite terminals in the same group is almost the same, and that each satellite terminal has data to transmit when it is woken up, thereby improving the utilization rate of the communication channel.

[0064] In some embodiments, for a service area reached by a satellite after a set time interval, the satellite terminals in that service area are grouped according to their previous access cycles and locations. This grouping occurs every set time interval; this grouping is dynamic, and for example, the set time interval is 5 minutes. The time each satellite takes to pass through each service area includes several set time intervals.

[0065] In some embodiments, within a three-dimensional space defined by access period, longitude, and latitude, satellite terminals in the service area are grouped using a clustering method based on their previous access periods, longitude, and latitude when the satellite arrives in the service area after a set time interval. For example, the clustering method may be the K-means method or the DBSCAN method.

[0066] S120: Periodically wake up each satellite terminal in the group to send access probes within the corresponding wake-up window of the group.

[0067] In this process, based on the grouping obtained in step S110, satellite terminals within each group are periodically woken up. When a satellite in that group has data to transmit, an access probe is sent within the wake-up window corresponding to that group. In all embodiments of this application, wake-up and hibernation are relative to the uplink direction of the satellite terminal, i.e., the direction from the satellite terminal to the satellite.

[0068] In some embodiments, for each satellite terminal within a group, a wake-up beacon (also known as a gradient wake-up beacon) for that group is broadcast periodically via the broadcast channel. Each group's wake-up beacon includes the group's ID, the wake-up window for the satellite terminals in that group, and the access channels allowed to be used. For example, a wake-up window is 2 milliseconds, and the access channel corresponds to an uplink frequency.

[0069] In some embodiments, each satellite terminal within a group obtains an access slot within the wake-up window corresponding to that group, and sends an access probe during that access slot. For example, a wake-up window is 2 milliseconds, and an access slot is 5 microseconds.

[0070] In some embodiments, the access time slot for each satellite terminal is obtained based on the ID of the satellite terminal; in other embodiments, the access time slot for each satellite terminal is obtained by hashing based on the ID of the satellite terminal and the ID of the group to which it belongs.

[0071] In some embodiments, the satellite also broadcasts the group to which each satellite terminal belongs, and the wake-up beacon includes the ID of each group so that the satellite terminal can obtain its own wake-up beacon.

[0072] In some embodiments, the wake-up window for each group of satellite terminals is set based on the time it takes for a satellite to pass over the top of that group. In other embodiments, the wake-up window for each group of satellite terminals is also set based on the scheduling of satellite terminals in that group according to service requirements, for example, scheduling for emergency services such as emergency rescue and firefighting.

[0073] S130: After successfully detecting the access probe of any satellite terminal, authorize the satellite terminal to send data to the satellite.

[0074] Once the satellite successfully detects the access probe of any satellite terminal, it sends data from the satellite terminal to the satellite through the authorization window of the broadcast channel.

[0075] In some embodiments, the access probe of each satellite terminal includes a common autocorrelation access pilot sequence and the ID of the satellite terminal. The access pilot sequence is known to the satellite and can be used to perform correlation detection on the access probe of the satellite terminal. On any access channel of the satellite, the access signal power is detected in each access time slot in the wake-up window of each group of satellite terminals. At this time, the access signal power is the radio power of the entire time slot of the access time slot, including the power of interference noise. When the access signal power exceeds a set power threshold, the access signal of the access time slot is subjected to sliding correlation with the common access pilot sequence to detect the correlation peak with pilot assistance. When only one correlation peak is detected, the access signal of the access time slot includes the access probe of the first satellite terminal. The ID of the first satellite terminal is parsed from the access signal according to the position of the correlation peak and the structure of the access probe.

[0076] In some embodiments, when the above sliding correlation detects more than one correlation peak, the first access probe signal is estimated based on the position and intensity of the strongest correlation peak; when the ID of the second satellite terminal is parsed from the first access probe signal, the first access probe signal includes the access probe of the second satellite terminal; the first access probe signal is subtracted from the access signal to obtain the remaining signal; the remaining signal is further sliding correlated with a common access pilot sequence to detect the access probes of other second satellite terminals included in the remaining signal.

[0077] In some embodiments, the access response frame following each wake-up window broadcasts one of the following messages: a message authorizing the satellite terminal (including the first satellite terminal and the second satellite terminal) with the resolved ID to transmit data, the backoff period N of the conflicting satellite terminals in the wake-up window, and a collision bitmap of the wake-up window. The maximum value of the number of backoff periods N changes positively with the collision probability of the conflicting satellite terminals in the wake-up window, and the collision bitmap is used to describe the access slots where collisions exist on each access channel in the wake-up window. The access response frame duration is very short, for example, 5 ms.

[0078] In summary, in the satellite terminal access control method of Embodiment 1 of this application, satellite terminals are grouped based on their terminal behavior. By combining spatiotemporal pre-diversion and a two-step access mechanism, the collision probability and power consumption of massive random terminal access are significantly reduced, thereby improving system throughput.

[0079] The following is combined Figure 2 Embodiment 2 of this application is described below.

[0080] Embodiment 2 of this application provides a satellite terminal access method, which runs on a satellite terminal and is used to access a satellite executing the control method described in Embodiment 1 of this application, and has all the advantages of Embodiment 1 of this application.

[0081] Figure 2 The flowchart of Embodiment 2 of this application is shown, including steps S210 to S220.

[0082] S210: When the satellite terminal receives a wake-up message broadcast by the satellite, it sends an access probe to the satellite.

[0083] Each satellite terminal continuously listens to broadcast messages from the overhead satellite, including wake-up beacons broadcast by the satellite. The wake-up beacons are broadcast periodically according to groups, where the group is the group divided in step S110 of Embodiment 1 of this application.

[0084] In some embodiments, the wake-up beacon for each group includes the group's ID, the wake-up window for the satellite terminal in that group, and the access channels that are allowed to be used. When the wake-up beacon includes the ID of the group to which the satellite terminal belongs, it is a wake-up message for that satellite terminal.

[0085] In some embodiments, each satellite terminal within a group obtains an access time slot within the wake-up window corresponding to that group, and sends an access probe during that access time slot. In some embodiments, the access time slot for each satellite terminal is obtained via hashing based on the satellite terminal's ID and the ID of its group.

[0086] In some embodiments, the access probe for each satellite terminal includes a common autocorrelation access pilot sequence and the ID of the satellite terminal.

[0087] S220: When the satellite terminal receives a satellite broadcast message authorizing it to send data, it sends data to the satellite.

[0088] In some embodiments, in the access response frame following each wake-up window, the satellite broadcasts one of the following messages: a message authorizing the satellite terminal (including the first satellite terminal and the second satellite terminal) with the resolved ID to send data, the backoff period N of the conflicting satellite terminal in the wake-up window, and the conflict bitmap of the wake-up window.

[0089] In some embodiments, the satellite terminal receives an authorization message containing its own ID in the access response frame received after the access probe's wake-up window, and then sends data to the overhead satellite. If the satellite terminal is still in backoff mode, the backoff ends.

[0090] In some embodiments, if the satellite terminal receives an access response frame after the access probe's wake-up window that does not contain an authorization message with its own ID and the received collision bitmap indicates that there is a collision in its access time slot, it will back off for N wake-up cycles before sending the access probe again.

[0091] In some embodiments, when transmitting data, the satellite also transmits its own position and access cycle to facilitate dynamic grouping before the satellite's next overhead pass.

[0092] The following is combined Figures 3 to 4 Embodiment 3 of this application is described below.

[0093] Embodiment 3 of this application provides an access method for a satellite Internet of Things system, which includes a more detailed method combining Embodiment 1 and Embodiment 2 of this application, and has all the advantages of Embodiment 1 and Embodiment 2 of this application.

[0094] For ease of explanation, let's take a typical low-Earth orbit satellite IoT system as an example. Low-Earth orbit satellites operate at an altitude of about 900 kilometers, and there are at least tens of thousands of low-power IoT terminals on the ground that periodically report data. For example, the IoT terminals are environmental monitoring sensors.

[0095] On the satellite side, this includes:

[0096] The onboard computer is responsible for running and maintaining the terminal behavior database and executing dynamic virtual grouping algorithms. This computer has basic storage and batch processing computing capabilities.

[0097] The transceiver is responsible for sending wake-up beacons and access response frames for authorizing satellite terminals to send data on the designated broadcast channel, and for receiving contention probes and complete data packets on the uplink service channel;

[0098] The signal processing unit consists of an FPGA (Field Programmable Gate Array) and a DSP (Digital Signal Processor). The FPGA is responsible for implementing fast arbitration logic (such as energy detection and response frame generation), while the DSP is responsible for running complex signal processing algorithms such as pilot-assisted serial interference cancellation.

[0099] On the satellite terminal side, this includes:

[0100] A typical low-power, narrowband IoT communication module that supports satellite communication protocol stacks. It has a built-in real-time clock and coarse positioning module (such as simplified positioning based on satellite navigation systems or position calculation based on ephemeris data from the last communication).

[0101] Figure 3 The flowchart of the access method according to Embodiment 3 of this application is shown, including steps S310 to S360. Steps S310, S320, S340, S343, S346, S349, and S360 are executed in the satellite, while steps S330, S335, S350, S353, and S356 are executed in the satellite terminal.

[0102] S310: The satellite dynamically groups satellite terminals within the ground service area that is about to pass overhead.

[0103] This step is executed on the satellite's onboard computer and includes the following sub-steps:

[0104] (1) Maintain the historical access database of satellite terminals. The satellite-side database records each satellite terminal ID and its corresponding historical access data (including historical access timestamp sequence, reporting period T, and the most recently reported latitude and longitude). For example, satellite terminal A is recorded as (satellite terminal ID_A, historical access timestamp sequence [t1, t2, ...], reporting period T_A=30 minutes, and the most recently reported latitude and longitude (E115.5°, N39.8°)).

[0105] (2) Dynamic grouping is triggered before the satellite enters a ground service area for a set period of time, and the onboard computer starts the grouping algorithm; for example, the set period of time is 5 minutes.

[0106] (3) Dynamically group satellite terminals within the ground service area through clustering, including:

[0107] a) Constructing a feature vector in three-dimensional space: For each satellite terminal, construct a three-dimensional feature vector [period factor, longitude, latitude], where "period factor" = the standardized period value (for example, 30 minutes is mapped to 0.5, 1 hour to 1, and 1 day to 24).

[0108] b) Grouping by clustering: Using the classic K-means or the more suitable DBSCAN clustering algorithm, satellite terminals with similar feature vectors are grouped into one class. For example, all satellite terminals with a reporting cycle of 25-35 minutes and a geographical location concentrated in one service area (latitude and longitude difference less than 0.1°) will be clustered into the same group.

[0109] (4) Assign a group identifier, wake-up time window and suggested access channel to each group.

[0110] i. Group Identifier: Assign a unique Group ID (GID) to each group. For example, the GID is 2 bytes.

[0111] ii. Wake-up Time Window: Based on the average reporting cycle of satellite terminals within the group and the satellite overpass time, a starting time offset (4 bytes, in milliseconds, relative to a system reference time) and a window duration (e.g., 2 seconds) are assigned to the group. The wake-up time windows of different groups are arranged sequentially in time, with slight overlap or intervals.

[0112] iii. Proposed set of access channels: Allocate a continuous or discrete set of proposed access channel resources (e.g., frequency points f1 to f10) for the group from the system uplink frequency band. Typically, the number of access channels allocated to a group is much smaller than the number of satellite terminals within the group, in order to introduce controlled competition.

[0113] S320: The satellite periodically sends wake-up beacons to satellite terminals in the current ground service area.

[0114] This step is performed at the satellite's transceiver. Each wake-up beacon consists of a short broadcast frame, the structure of which is shown below:

[0115] |Frame header|Target GID|Wake-up window start offset|、Suggested access channel bitmap|CRC check|.

[0116] For example, the proposed access channel bitmap is 10 bytes, with each bit indicating whether a channel is available.

[0117] After entering the ground service area, the satellite first broadcasts the group to which each satellite terminal in the ground service area belongs. Following the group order determined in step S310, it periodically and sequentially broadcasts wake-up beacons for different GIDs on the downlink broadcast channel. For example, at time T0, a beacon for GID=1 is broadcast, instructing it to wake up at T0+100ms; at T0+50ms, a beacon for GID=2 is broadcast, instructing it to wake up at T0+180ms, and so on.

[0118] S330: The satellite terminal determines whether the GID in the received wake-up beacon matches its own.

[0119] Each satellite terminal continuously listens to the broadcast channel. When it receives a wake-up beacon and the GID in the beacon matches its own GID, the satellite terminal is woken up and executes step S335; otherwise, it executes step S356.

[0120] S335: The satellite terminal sends an access probe during the access time slot of the access channel.

[0121] This step is performed on the satellite terminal side and includes the following steps:

[0122] (1) When each satellite terminal receives a wake-up beacon and the GID in it matches its own GID, the satellite terminal is woken up and the start time of the wake-up window and the set of recommended access channels in the wake-up beacon are recorded.

[0123] (2) Each satellite terminal obtains an access time slot according to equation (1) within the wake-up window of its group.

[0124] Micro-slot index = Hash(satellite terminal ID || GID) mod N (1)

[0125] Where N is the total number of micro-slots contained within the window, and || denotes splicing. Each access slot is a micro-slot, long enough to send only one access probe (0.5 milliseconds for example).

[0126] (3) Each satellite terminal sends an access probe in the access time slot it has obtained.

[0127] Each access probe includes:

[0128] ① Common pilot sequence: A known pseudo-random sequence (such as the Zadoff-Chu sequence) with good autocorrelation and cross-correlation properties is used, with a length of 128 chips.

[0129] ② Fingerprint field: contains simplified identity information of the terminal, such as (satellite terminal ID (4 bytes) || status flag (1 byte)), and performs forward error correction encoding.

[0130] ③ At the calculated micro-timeslot start time, the satellite terminal sends a contention probe (a data packet with a total length of about 20 bytes, much smaller than 100 bytes) on a channel randomly selected from the set of suggested access channels.

[0131] S340: The satellite performs collision detection on the radio signals received from the wake-up window of each group.

[0132] This step is implemented in the FPGA of the satellite's signal processing unit and includes the following sub-steps:

[0133] (1) During the predetermined wake-up window reception period, the FPGA performs power detection on the wireless signal received in each access slot on each access channel. If the received power exceeds the set power threshold, it is determined that there is a wireless signal from the access probe of the satellite terminal in that access slot.

[0134] (2) For the access time slot of the wireless signal of the access probe with satellite terminal, the FPGA attempts to perform sliding correlation using the known common pilot sequence. If only one clear and sharp correlation peak appears, it is determined to be a collision-free scenario, and the received wireless signal is a collision-free access probe. The corresponding satellite terminal ID is detected from the position of the correlation peak. If multiple correlation peaks appear, it is determined to be a collision scenario.

[0135] S343: Determine if there is an access probe conflict.

[0136] This step is implemented in the FPGA of the satellite's signal processing unit. If there is a conflict, step S346 is executed, followed by step S349; otherwise, step S349 is executed directly.

[0137] The conflict here refers to the collision of access probes. Figure 4 The diagram illustrates a scenario of access probe collisions among the activated satellite terminals in this embodiment. The diagram shows 7 activated satellite terminals, with 3 activated satellite terminals sending access probes that do not collide, while the other 4 activated satellite terminals send access probes that collide in pairs.

[0138] S346: Separate access probes for lightweight conflict scenarios.

[0139] In this scenario, a lightweight collision scenario occurs when multiple related peaks appear in any access time slot of any access channel, and the number of peaks is less than a set number. In this lightweight collision scenario, the radio signal in the access time slot is the superimposed signal from the access probes of multiple satellite terminals. This step is implemented in the DSP of the satellite's signal processing unit to separate the superimposed signal, including:

[0140] ① Using the common pilot sequence, estimate the channel impulse response, received amplitude, and position of the strongest component corresponding to the strongest correlation peak in the superimposed signal.

[0141] ② Using the estimated impulse response parameters, received amplitude, and the position of the strongest correlation peak, the signal of the strongest component is reconstructed in the time or frequency domain using the superimposed signal. When the corresponding satellite terminal ID is parsed from the signal of the strongest component, proceed to ③; otherwise, the separation ends, and step S346 is also completed.

[0142] ③ Subtract the strongest reconstructed signal from the received superimposed signal to obtain the remaining signal.

[0143] ④ Repeat steps ① to ③ with the remaining signal as the superimposed signal, attempt to demodulate the strongest signal in the remaining signal, and attempt to parse the corresponding satellite terminal ID. If the signal that cannot be separated cannot be parsed to obtain the corresponding satellite terminal ID, then the separation ends, and step S346 is also completed.

[0144] S349: Quick broadcast arbitration of satellite terminals sending access probes.

[0145] This step is executed collaboratively by the FPGA of the signal processing unit and the communication module in the transceiver. For the detected terminal ID, within a very short time (e.g., 5 milliseconds) after the wake-up window corresponding to its packet ends, the satellite immediately transmits an access response frame via the downlink broadcast channel. This frame structure includes:

[0146] ① Success List: Lists the IDs of all satellite terminals that were detected as collision-free and whose fingerprint fields were successfully decoded;

[0147] ② Authorized resource indication: Allocate specific time and frequency resources for each satellite terminal in the list to subsequently transmit complete data packets;

[0148] ③ Collision Indication Bitmap: Indicates which channel / access slot combinations have collided;

[0149] ④ Unified backoff command: It is recommended that the collision satellite terminal retry in the Nth wake-up cycle, where N is a broadcast random number. The maximum value of N changes positively with the collision probability. Here, the wake-up cycle refers to the broadcast cycle of the wake-up beacon.

[0150] If the corresponding satellite terminal ID is successfully resolved in a lightweight conflict scenario, supplementary authorization for that satellite terminal ID will be broadcast through subsequent broadcast frames (or the next response frame).

[0151] S350: The satellite terminal that receives the access response frame determines whether it has received an authorization message for itself.

[0152] If the access response frame includes the ID of any satellite terminal, then it includes an authorization message for that satellite terminal. If the access response frame includes an authorization message for this terminal, step S353 is executed; otherwise, step S356 is executed.

[0153] S353: The satellite terminal transmits data on the specified precise time and frequency resources.

[0154] Specifically, when the access response frame received by the satellite terminal includes an authorization message for the satellite terminal, it sends its complete application layer data packet, which is 100 bytes or more in length, on the precise time-frequency resources specified within the frame. This data packet includes not only the data to be sent but also its own access cycle and location.

[0155] S356: The satellite terminal receives the backoff command and enters the hibernation period for the next cycle.

[0156] When the received access response frame does not include a satellite terminal authorized by itself and the access channel / access time slot used by itself is in conflict with the satellite terminal in the conflict bitmap, it follows the unified backoff instruction in the frame and immediately enters a sleep state until it is awakened to listen after the number of wake-up cycles specified in the frame, thus completely avoiding the invalid "send-collision-retransmit" cycle.

[0157] S360: The satellite receives data packets from the satellite terminal.

[0158] Among them, when the satellite receives the data packet of the current ground service area, it also receives the access cycle and location of the satellite terminal, and constantly monitors whether to enter the next ground service area before executing step S310.

[0159] The following simulation scenario illustrates the effectiveness of this application: 50,000 terminals are randomly distributed within the satellite coverage area, with reporting cycles ranging from 10 minutes to 24 hours. The simulation results using the method described in this embodiment are as follows:

[0160] ① Reduced collision probability: Within any 2-second wake-up window, the number of competing satellite terminals is diverted to approximately 300-800. They compete for dozens of channels and hundreds of micro-time slots, reducing the initial access probe transmission collision probability to approximately 15%-25%.

[0161] ② Improved throughput: After collision separation, some collision access probes were successfully recovered, which improved the success rate of single access attempts and increased the system's normalized throughput (the proportion of time slots occupied by successfully sent data packets) to between 0.55 and 0.65.

[0162] ③ Reduced power consumption of satellite terminals: During a single access attempt, the satellite terminal only needs to be active for approximately 150 milliseconds (including listening to beacons, sending probes, and receiving response frames). If data is transmitted, additional data packet transmission time is added. Compared to the several seconds of listening and retransmission in traditional solutions, power consumption is reduced by more than an order of magnitude.

[0163] ④ No increase in satellite load: The grouping algorithm is executed once every time it passes over the top (approximately every minute), and the amount of computation is controllable; the detection and arbitration of the FPGA are hardware logic with extremely low latency; the interference separation of the DSP is only for a few collision time slots, and the processing load is within the typical DSP capability range.

[0164] The following is combined Figure 5 Example 4 of this application is described below.

[0165] Embodiment 4 of this application provides a satellite terminal access control device, which is located on a satellite and executes a satellite terminal access control method according to Embodiment 1 of this application, and has all its advantages.

[0166] Figure 5 The structure of the device described in Embodiment 4 of this application is shown, including: a grouping module 510, a wake-up module 520, and an authorization module 530.

[0167] The grouping module 510 is used to group satellite terminals based on their previous location and access period. For its working principle and advantages, please refer to step S110 of Embodiment 1 of this application.

[0168] The wake-up module 520 is used to periodically wake up each satellite terminal in the group to send access probes within the corresponding wake-up window of the group. For its working principle and advantages, please refer to step S120 of Embodiment 1 of this application.

[0169] The authorization module 530 is used to authorize any satellite terminal to send data to the satellite after successfully detecting the access probe of any satellite terminal. For its working principle and advantages, please refer to step S130 of Embodiment 1 of this application.

[0170] The following is combined Figure 6 Example 5 of this application is described below.

[0171] Embodiment 5 of this application provides a satellite terminal access device, which is located on a satellite terminal and executes a satellite access control method according to Embodiment 2 of this application, and has all its advantages.

[0172] Figure 6 The structure of the apparatus described in Embodiment 5 of this application is shown, including: an access module 610 and a transmission module 620.

[0173] The access module 610 is used to send an access probe to the satellite when the satellite terminal receives a wake-up message broadcast by the satellite. For its working principle and advantages, please refer to step S210 of Embodiment 2 of this application.

[0174] The transmitting module 620 is used to transmit data to the satellite when the satellite terminal receives a satellite broadcast message authorizing it to transmit data. For its working principle and advantages, please refer to step S220 of Embodiment 2 of this application.

[0175] Note that the above are merely preferred embodiments and the technical principles employed in this application. Those skilled in the art will understand that this application is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of this application, all of which fall within the scope of protection of this application.

Claims

1. A satellite terminal access control method, characterized in that, Operating on the satellite side, including: Satellite terminals are grouped based on their previous location and access period; Each satellite terminal in the group is periodically woken up to send an access probe within the corresponding wake-up window of the group. After successfully detecting the access probe of any satellite terminal, the satellite terminal is authorized to send data to the satellite.

2. The method according to claim 1, characterized in that, The grouping of satellite terminals based on their previous location and access period includes: For the service area that a satellite arrives at after a set time, the satellite terminals that have accessed the service area are grouped according to their previous access cycles and locations.

3. The method according to claim 2, characterized in that, Based on the previous access cycles and locations of each satellite terminal in the service area, the accessing satellite terminals are grouped, including: In a three-dimensional space with access period, longitude, and latitude as dimensions, satellite terminals in the service area are grouped according to their previous access periods, longitude, and latitude using a clustering method.

4. The method according to claim 1, characterized in that, Periodically wake up each satellite terminal within the group to send access probes within the corresponding wake-up window for that group, including: For each satellite terminal in a group, a wake-up beacon for that group is broadcast during the broadcast channel period. The wake-up beacon for each group includes the wake-up window of the satellite terminals in that group and the access channels that can be occupied.

5. The method according to claim 4, characterized in that, Each satellite terminal's access probe includes a common autocorrelation access pilot sequence and the satellite terminal's ID; the access probe for detecting satellite terminals includes: On any access channel of the satellite, detect the access signal power in each access slot of the wake-up window of each group of satellite terminals; When the power exceeds the set power threshold, the access signal of the access time slot is subjected to a sliding correlation with the access pilot sequence; When only one correlation peak is detected, the ID of the first satellite terminal is parsed from the access signal based on the position of the correlation peak.

6. The method according to claim 5, characterized in that, The access probe for the detection satellite terminal also includes: When the sliding correlation detects more than one correlation peak, the first access probe signal is estimated from the access signal based on the position and intensity of the strongest correlation peak. When the ID of the second satellite terminal is parsed from the first access probe signal, the first access probe signal is subtracted from the access signal to obtain the remaining signal; The remaining signal is then further correlated with the access pilot sequence to detect access probes of other second satellite terminals included in the remaining signal.

7. The method according to claim 5 or 6, characterized in that, Also includes: The access response frame following the wake-up window broadcasts one of the following messages: The message that the satellite terminal whose ID has been parsed is authorized to send data, the backoff period N of the conflicting satellite terminals in the wake-up window, and the conflict bitmap of the wake-up window.

8. A satellite terminal access method, characterized in that, For satellite terminal access to a satellite performing any of the methods described in claims 1 to 7, comprising: When the satellite terminal receives a wake-up message broadcast by the satellite, it sends an access probe to the satellite. When the satellite terminal receives a message from the satellite broadcast authorizing it to send data, it sends data to the satellite.

9. A satellite terminal access control device, characterized in that, include: The grouping module is used to group satellite terminals based on their previous location and access period; The wake-up module is used to periodically wake up each satellite terminal in the group to send access probes within the corresponding wake-up window of the group. The authorization module is used to authorize any satellite terminal to send data to the satellite after successfully detecting the access probe of any satellite terminal.

10. A satellite terminal access device, characterized in that, For satellite terminal access to a satellite performing any of the methods described in claims 1 to 7, comprising: The access module is used to send an access probe to the satellite when the satellite terminal receives a wake-up message broadcast by the satellite. The transmitting module is used to transmit data to the satellite when the satellite terminal receives a message from the satellite broadcasting authorizing it to transmit data.

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