Method and apparatus for frequency division joint communication based on overlapping multiple beams

Abstract

The application provides an overlapping multi-beam based frequency division joint communication method and device, and relates to the technical field of satellite communication. The method comprises the following steps: receiving a selected frequency frame transmitted by a communication ground station through a satellite, the selected frequency frame being a full-1 sequence after frequency spreading, and the selected frequency frames of different beams being distinguished through different uplink frequency points. The selected frequency frame transmitted by the communication ground station is captured in a selected frequency state, and all overlapping beams in which a communication terminal is located are determined according to the capture result. A to-be-transmitted signal is framed to generate a service frame, the service frame is synchronously transmitted on the frequency points corresponding to the determined all overlapping beams through multi-beam joint modulation. The multi-beam joint transmission signal is transparently forwarded to the communication ground station through the satellite, the communication ground station separates the signals of each beam and completes the despreading operation to obtain symbol-level information, and then the signals are coherently combined through a cross-entropy estimation algorithm to extract effective data information. The multi-beam joint communication is realized, the power spectral density of the transmitted signal is reduced, and the signal concealment is improved.

Description

Technical Field

[0001] This invention relates to the field of satellite communication technology, and in particular to a frequency division joint communication method and apparatus based on overlapping multi-beams. Background Technology

[0002] With the rapid development of satellite communication technology, spectrum resources are becoming increasingly scarce, and the traditional fixed allocation model of licensed spectrum can no longer meet diverse communication needs. Unlicensed spectrum sharing access technology, due to its flexibility and low cost, has gradually become a research hotspot in the field of wireless communication, and high-orbit satellite multi-beam systems are one of its popular research scenarios. High-orbit satellite multi-beam systems mainly improve spectrum efficiency through frequency reuse technology, that is, adjacent beams use different frequency bands to avoid co-channel interference. However, due to the scarcity of spectrum resources, traditional frequency reuse schemes require reserve guard bands between beams, leading to reduced spectrum utilization. Furthermore, in existing technologies, user communication terminals typically communicate using only a single beam, which is susceptible to signal attenuation or blockage in edge areas, requiring increased transmission power to ensure link quality, resulting in increased signal power spectral density and increased risk of interception or interference. Summary of the Invention

[0003] This invention provides a frequency division multiplexing (FDM) joint communication method and apparatus based on overlapping multi-beams, to address the shortcomings of existing technologies such as excessively high power spectral density and insufficient signal concealment. This invention leverages the characteristics of beam overlap regions to achieve multi-beam joint communication, thereby reducing the power spectral density of the transmitted signal and improving signal concealment. The technical solution proposed by this invention is as follows:

[0004] In a first aspect, the present invention provides a frequency division joint communication method based on overlapping multi-beams, applied to a communication terminal, comprising:

[0005] The receiver receives frequency selection frames relayed by the ground station via satellite. The frequency selection frames are spread-spectrum all-1 sequences, and the frequency selection frames of different beams are distinguished by different uplink frequency points. Each frequency point corresponds uniquely to a beam.

[0006] In frequency-selective mode, capture the frequency-selective frames sent by the communication ground station, and determine all overlapping beams in which the communication terminal is located based on the frequency-selective frame capture results;

[0007] The signal to be transmitted is framed to generate a service frame. The service frame is then synchronously transmitted on the corresponding frequency points of all the determined overlapping beams through multi-beam joint modulation to form a multi-beam joint transmission signal.

[0008] The multi-beam joint transmission signal is transparently forwarded to the communication ground station via satellite. The communication ground station then separates the signals of each beam in the multi-beam joint transmission signal, performs despreading operations to obtain symbol-level information, and coherently merges the signals using a cross-entropy estimation algorithm to extract effective data information.

[0009] Optionally, in the frequency selection state, the communication terminal captures all satellite downlink frequency points that may have frequency selection frames. The frequency selection frame capture process adopts the same symbol rate, coding rate and coding method as the communication ground station.

[0010] Optionally, the frame structure of the service frame includes a pilot header, a frame synchronization header, a service segment, and a data segment.

[0011] Optionally, the frequency points transmitted in the frequency selection frame include the uplink frequency points of the communication ground station corresponding to all beams.

[0012] Optionally, the time interval for transmitting frequency-selective frames is a fixed time t, and the duration of the frequency-selective state is 2t.

[0013] Secondly, this invention provides a frequency division joint communication method based on overlapping multi-beams, applied to a communication ground station, comprising:

[0014] Frequency selection frames are sent to all beams of the satellite. The frequency selection frames are spread-spectrum all-1 sequences, and the frequency selection frames of different beams are distinguished by different uplink frequency points. Each frequency point corresponds uniquely to a beam.

[0015] The satellite receives the multi-beam joint transmission signal returned by the communication terminal. The multi-beam joint transmission signal is the same service frame signal synchronously transmitted by the communication terminal on the corresponding frequency points of all overlapping beams.

[0016] After separating the signals of each beam in the multi-beam joint transmission signal and completing the despreading operation to obtain symbol-level information, the signals are coherently combined using the cross-entropy estimation algorithm to extract effective data information.

[0017] Optionally, the frame structure of the service frame includes a pilot header, a frame synchronization header, a service segment, and a data segment.

[0018] Optionally, the frequency points transmitted in the frequency selection frame include the uplink frequency points of the communication ground station corresponding to all beams.

[0019] Optionally, after separating the signals of each beam in the multi-beam joint transmission signal and completing the despreading operation to obtain symbol-level information, the signals are coherently combined using a cross-entropy estimation algorithm to extract effective data information, including:

[0020] The signals of each beam in the received multi-beam joint transmission signal are separated, and the separated beam signals are despread to recover the symbol-level information.

[0021] A cross-entropy estimation algorithm is used to dynamically weight and merge the symbol-level information of multiple beams. The original data sequence with the highest probability is determined through iterative calculation, and effective data information is extracted.

[0022] Thirdly, the present invention provides a frequency division joint communication device based on overlapping multi-beams, including a multi-beam service transmission unit located on a communication terminal and a multi-beam service receiving unit located on a communication ground station.

[0023] The multi-beam service transmission unit includes a frequency-selective frame receiving module and a service frame transmission module that operate in parallel and are connected to each other:

[0024] The frequency selection frame receiving module is used to receive frequency selection frames relayed by the communication ground station via satellite. The frequency selection frames are spread-spectrum all-1 sequences, and the frequency selection frames of different beams are distinguished by different uplink frequency points, with each frequency point uniquely corresponding to a beam. The module also captures the frequency selection frames sent by the communication ground station in the frequency selection state and determines all overlapping beams in which the communication terminal is located based on the frequency selection frame capture results.

[0025] The service frame transmission module is used to frame the signal to be transmitted into service frames, and synchronously transmit the service frames on the corresponding frequency points of all determined overlapping beams through multi-beam joint modulation to form a multi-beam joint transmission signal; and transparently forward the multi-beam joint transmission signal to the communication ground station through the satellite.

[0026] The multi-beam service receiving unit includes a service frame receiving module and a frequency-selective frame transmitting module that operate in parallel and are connected to each other:

[0027] The frequency selection frame transmission module is used to transmit frequency selection frames to all beams of the satellite. The frequency selection frame is a spread spectrum sequence of all 1s, and the frequency selection frames of different beams are distinguished by different uplink frequency points. Each frequency point corresponds uniquely to a beam.

[0028] The service frame receiving module is used to receive the multi-beam joint transmission signal returned by the communication terminal via satellite. The multi-beam joint transmission signal is the same service frame signal synchronously transmitted by the communication terminal on the corresponding frequency points of all overlapping beams. After separating the beam signals in the multi-beam joint transmission signal and completing the despreading operation to obtain symbol-level information, the module coherently merges the signals using a cross-entropy estimation algorithm to extract effective data information.

[0029] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0030] The frequency division multiplexing (FDM) joint communication method and apparatus based on overlapping multi-beams provided by this invention disperses signal energy across multiple beams rather than concentrating it at a single point by overlapping multiple beams in the target area. Simultaneously, different beams correspond to independent frequency points, avoiding energy concentration caused by spectral conflicts and further dispersing signal energy in the frequency domain. This dual dispersion mechanism of space and spectrum fundamentally solves the problem of excessively high power spectral density in single-beam communication. The frequency selection frame uses a spread-spectrum all-1 sequence, whose low correlation characteristics make the signal difficult to extract from noise, increasing detection difficulty. The independent frequency point design of different beams reduces inter-beam interference through frequency isolation, making it difficult for detection equipment to reconstruct the original signal from a single frequency point. Furthermore, the spectral mosaic formed by multi-beam joint transmission further obscures signal characteristics, requiring detection equipment to simultaneously analyze multiple frequency points to reconstruct information, significantly improving signal concealment.

[0031] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is one of the flowcharts of the frequency division joint communication method based on overlapping multi-beams provided by the present invention.

[0035] Figure 2 This is a schematic diagram of the handshake process between the communication terminal and the communication ground station provided by the present invention.

[0036] Figure 3 This is a schematic diagram of the frequency-selective frame structure provided by the present invention.

[0037] Figure 4 This is a schematic diagram of the service frame structure provided by the present invention.

[0038] Figure 5 This is a schematic diagram of the frequency selection frame transmission process of the communication ground station provided by the present invention.

[0039] Figure 6This is a schematic diagram of the communication terminal service frame transmission process provided by the present invention.

[0040] Figure 7 This is a schematic diagram of the communication ground station service frame reception process provided by the present invention.

[0041] Figure 8 This is the second flowchart of the frequency division joint communication method based on overlapping multi-beams provided by the present invention.

[0042] Figure 9 This is a schematic diagram of the structure of the frequency division joint communication device based on overlapping multi-beams provided by the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0044] The following is combined Figures 1-9 This invention describes a frequency division joint communication method and apparatus based on overlapping multi-beams.

[0045] Figure 1 This is one of the flowcharts illustrating the frequency division joint communication method based on overlapping multi-beams provided in this application, which is applied to a communication terminal. Current communication methods mostly use a single beam, failing to effectively utilize the advantages of beam overlap areas and wasting spectrum resources. The method of this invention, however, can utilize the entire beam overlap area where the communication terminal is located, effectively utilizing communication bandwidth resources and avoiding bandwidth waste. Furthermore, compared to current communication methods, using multi-beam overlap area communication can effectively reduce the power spectral density of the transmitted signal, effectively improving the concealment of the transmitted signal and enhancing the security of the communication terminal's usage scenario. (Refer to...) Figure 1 As shown, the method includes the following:

[0046] S110. Receive the frequency selection frame relayed by the communication ground station via satellite. The frequency selection frame is a spread spectrum sequence of all 1s, and the frequency selection frames of different beams are distinguished by different uplink frequency points. Each frequency point corresponds uniquely to a beam.

[0047] The ground communication station generates a spread spectrum sequence of all 1s as the frequency selection frame, which is then transmitted on all beams. The ground communication station transmits the same frequency selection frame on different frequencies, and the satellite forwards it to the corresponding beam according to its frequency. Each satellite beam is assigned a unique uplink and downlink frequency, and the frequency selection frame distinguishes different beams by these different frequencies.

[0048] For example: beam A → frequency point f1, beam B → frequency point f2, beam C → frequency point f3.

[0049] The fixed mapping between frequency points and beams enables communication terminals to clearly identify available overlapping beams.

[0050] S120. In frequency-selective mode, capture the frequency-selective frame sent by the communication ground station, and determine all overlapping beams in which the communication terminal is located based on the frequency-selective frame capture result.

[0051] When a communication terminal is powered on, it enters frequency selection mode and determines its location within an overlapping beam by capturing the frequency selection frames sent by the ground communication station. For example, if the communication terminal captures a frequency selection frame at frequency f1, it determines that the communication terminal is located in the coverage area of ​​beam A; if it captures frequency selection frames f1 and f2, it determines that the communication terminal is located in the overlapping area of ​​beams A and B.

[0052] In frequency-selective mode, the communication terminal completes beam acquisition and determination through the following steps:

[0053] First, the ground communication station sends specific frequency-selective frame signals to all satellite beams. These frequency-selective frames are spread-spectrum sequences of all 1s, with each beam's corresponding frequency-selective frame distinguished by a different uplink frequency. After receiving these frequency-selective frames, the satellite transparently forwards them to the corresponding downlink beam coverage area, ensuring that every geographical region can receive the frequency-selective frames at the specific frequency.

[0054] When the communication terminal powers on, it immediately enters frequency selection mode. In this mode, the terminal performs a comprehensive scan and search of all pre-stored possible downlink frequencies. For each frequency, the terminal attempts to acquire the signal, a process involving two key steps: spreading code matching and frequency offset search. The terminal uses the same spreading code as the ground station to search for frequency offset and code phase, and determines whether a valid frequency-selective frame signal has been successfully acquired through relevant detection.

[0055] Successfully capturing a frequency-selective frame requires meeting two main conditions: first, the correlation peak value must exceed a set detection threshold; and second, the signal strength must meet the minimum receiver sensitivity requirement. Whenever a communication terminal successfully captures a frequency-selective frame at a certain frequency, it determines whether it is currently within the coverage area of ​​the corresponding beam based on the preset frequency-beam correspondence.

[0056] Because satellite beams have overlapping coverage areas, a communication terminal may simultaneously capture selected frames on multiple different frequencies. In this case, the communication terminal records the information of all successfully captured frequencies and determines the total number of overlapping beams it is currently in based on the beam numbers corresponding to these frequencies. For example, if the communication terminal captures selected frames on both frequencies f1 and f2, and f1 corresponds to beam A and f2 corresponds to beam B, then it is determined that the communication terminal is located within the overlapping coverage area of ​​beams A and B.

[0057] The entire frequency selection process must be completed within a specified time, not exceeding twice the frequency selection frame transmission period. After completing the scan of all frequency points, the communication terminal will transmit all identified overlapping beams to the subsequent service transmission module, preparing for multi-beam joint communication. If no frequency selection frame is captured within the specified time, the communication terminal will determine that the frequency selection has failed and needs to restart the frequency selection process. This ensures that the communication terminal can accurately identify all available beam resources, providing the necessary prerequisites for subsequent multi-beam joint communication. Through full-frequency scanning and capture determination criteria, the system can effectively avoid beam misses, ensuring that the communication terminal can obtain the expected communication performance in any location.

[0058] S130. The signal to be transmitted is framed to generate a service frame. The service frame is synchronously transmitted on the corresponding frequency points of all the determined overlapping beams through multi-beam joint modulation to form a multi-beam joint transmission signal.

[0059] After determining all overlapping beams, the communication terminal will perform the following key steps to complete signal transmission:

[0060] 1. Service Frame Generation: The communication terminal frames the signals to be transmitted according to the frame structure. The generated service frame strictly consists of four parts: a pilot header for receiver synchronization, a frame synchronization header providing a timing reference, a service segment carrying control information, and a data segment carrying the payload. This frame structure design maintains compatibility with frequency-selective frames to ensure consistency in system processing.

[0061] 2. Multi-beam modulation processing: The service frame adopts Direct Sequence Spread Spectrum - Binary Phase Shift Keying (DSSS-BPSK) modulation. First, the spectrum is spread using a specific spreading code (such as Gold code), and then carrier modulation is performed. The modulation parameters remain consistent across all overlapping beams, including the same spreading factor, symbol rate, and carrier phase.

[0062] 3. Multi-beam synchronous transmission: The communication terminal synchronously transmits the same service frame on all corresponding frequency points of the determined overlapping beams. Each frequency point is configured with an independent transmission channel, and the channels are strictly synchronized, with the delay deviation controlled within 10% of the symbol period. The same timing reference as the frequency selection frame of the communication ground station is used.

[0063] 4. Formation of joint transmission signal: After the multi-beam signal is transparently relayed by the satellite, the satellite only performs frequency conversion and signal amplification, maintaining the independent transmission path of each beam signal, without changing the modulation characteristics and frame structure of the signal, thus forming a multi-beam joint transmission signal.

[0064] S140. The multi-beam joint transmission signal is transparently forwarded to the communication ground station via satellite. The communication ground station separates the signals of each beam in the multi-beam joint transmission signal and completes the despreading operation to obtain symbol-level information. Then, the signals are coherently merged using the cross-entropy estimation algorithm to extract effective data information.

[0065] The satellite transparently forwards service frames to the ground communication station based on their radio frequency points (e.g., f1, f2), and forwards service frames of different beams according to preset downlink frequency mapping rules (e.g., f1→f1', f2→f2'). The satellite only performs signal amplification and frequency conversion, without decoding or modulation, ensuring that the signal characteristics are completely preserved. For example, the uplink frequency f1 (2GHz) is converted to the downlink frequency f1' (10GHz), while the signal power is amplified to compensate for transmission loss.

[0066] Example: A communication terminal sends a service frame at frequency f1 of beam 1. The satellite converts the frequency to f1' and forwards it to the communication ground station. The communication terminal sends a service frame at frequency f2 of beam 2. The satellite converts the frequency to f2' and forwards it to the communication ground station. The communication ground station receives signals from both frequency f1' and f2', forming a multi-beam joint transmission signal.

[0067] The ground communication station captures all downlink frequency signals (such as f1', f2') through spectrum scanning, determines the beam containing the service frame based on the selected frequency frame, and performs signal processing algorithms such as despreading, cross-entropy reception estimation, frame synchronization, demodulation, and decoding to parse the service frame information. For example, the selected frequency frame contains beam identification information, which the ground communication station can use to identify that f1' corresponds to beam 1 and f2' corresponds to beam 2. The ground communication station verifies the parsed data; if the verification passes, communication is considered successful; otherwise, the signal needs to be reacquired or a retransmission request needs to be made.

[0068] The frequency division multiplexing (FDM) joint communication method based on overlapping multi-beams provided by this invention disperses signal energy across multiple beams rather than concentrating it at a single point by overlapping multiple beams in the target area. Simultaneously, different beams correspond to independent frequency points, avoiding energy concentration caused by spectral conflicts and further dispersing signal energy in the frequency domain. This dual dispersion mechanism of space and spectrum fundamentally solves the problem of excessively high power spectral density in single-beam communication. The frequency selection frame uses a spread-spectrum all-1 sequence, whose low correlation characteristics make the signal difficult to extract from noise, increasing detection difficulty. The independent frequency point design of different beams reduces inter-beam interference through frequency isolation, making it difficult for detection equipment to reconstruct the original signal from a single frequency point. Furthermore, the spectral mosaic formed by multi-beam joint transmission further obscures signal characteristics, requiring detection equipment to simultaneously analyze multiple frequency points to reconstruct information, significantly improving signal concealment.

[0069] Existing single-beam communication systems are limited by fixed frequency points and beam coverage, making them difficult to adapt to complex and ever-changing communication needs. This invention, however, constructs a highly flexible communication system through a multi-beam joint transmission and transparent satellite relay architecture. The communication terminal can dynamically select overlapping beams based on the frequency selection frame acquisition results, without the need for pre-configuration of fixed frequency points; the satellite, acting as a relay node, only needs to transparently relay the multi-beam joint transmission signal, eliminating the need for complex decoding processing. This design enables the system to quickly adapt to different communication scenarios.

[0070] In traditional multi-beam independent communication modes, each beam transmits data from different users independently. While this can increase system throughput, it fails to effectively utilize the energy gain in the beam overlap region. For example, the signal strength in the overlap region of two beams is twice that of a single beam, but it only carries data from a single user, resulting in an energy utilization rate of only 50%. This invention, however, uses multi-beam joint transmission, enabling the communication terminal to synchronously transmit service frames on corresponding frequencies of multiple overlapping beams. The signal energy is spatially superimposed, but the frequencies remain independent. For example, three beams form a joint transmission signal in the overlap region, with the signal energy spatially superimposed but the frequencies independent. After the three beams are combined, although the signal strength in the overlap region is three times that of a single beam, the frequency bandwidth expands to 3Hz, and the power spectral density (PSD) drops to one-third of that of a single beam, resulting in an overall energy utilization rate increase of more than three times.

[0071] In some embodiments, during the frequency selection state, the communication terminal captures all satellite downlink frequency points that may have frequency selection frames. The frequency selection frame capture process uses the same symbol rate, coding rate, and coding method as the communication ground station.

[0072] By adopting the same symbol rate, coding rate, and coding method as the ground station, the communication terminal can directly parse the frequency-selective frames generated by the ground station without the need for additional decoding modules with different parameters. This parameter consistency eliminates the technical barriers between the communication terminal and the ground station, enabling seamless integration in signal processing. Because the parameters of the communication terminal and the ground station are consistent, the acquisition process of the frequency-selective frame can skip the parameter negotiation stage and directly enter the signal demodulation stage. This acquisition mechanism significantly shortens the frequency search time, making it particularly suitable for emergency communication scenarios requiring rapid response. Parameter consistency ensures the continuity of signal transmission, avoiding transmission interruptions caused by parameter adjustments. The communication terminal can fully utilize the coding gain configured by the ground station to achieve a higher data transmission rate under the same spectrum resources, thereby improving the overall system throughput. Simultaneously, the unified coding method means that the communication terminal and the ground station use the same error correction mechanism, effectively resisting noise and interference in the satellite channel. Even if the signal is distorted during transmission, the communication terminal can still recover the original data through its built-in decoding algorithm, ensuring the reliability of the communication link. In multi-frequency switching scenarios, parameter consistency enables the communication terminal to quickly adapt to the signal characteristics of new frequencies. Without the need to reconfigure decoding parameters, communication terminals can seamlessly switch between different frequency points, avoiding communication interruptions caused by parameter adjustments. Furthermore, parameter consistency allows communication terminals to simultaneously access multiple ground stations using the same standard, providing a technological foundation for building inter-satellite / satellite-ground hybrid networks. The ability of communication terminals to freely switch between different network nodes expands the application scope of satellite communication.

[0073] like Figure 2 The diagram shows the handshake process between a communication terminal and a ground communication station. The specific steps are as follows:

[0074] 1. The ground communication station transmits frequency-selective frames to the satellite on all beams.

[0075] Among them, the communication ground station uses a specific spreading code, radio frequency point, symbol rate, transmission power, coding rate and coding method (the specificity here refers to the communication terminal T, that is, the communication ground station belonging to the communication system needs to use the same spreading code, radio frequency point, symbol rate, transmission power, coding rate and coding method when sending frequency selection frames to the communication terminal) to send frequency selection frames to the satellite.

[0076] The format of the frequency-selective frame sent is as follows: Figure 3 As shown, a pilot head required for communication reception is required.

[0077] The frequency points transmitted in the frequency selection frame include the uplink frequencies of all communication ground stations corresponding to all beams. The frequency points transmitted in the frequency selection frame cover the uplink frequencies of all communication ground stations corresponding to all beams; that is, each beam needs to be allocated an independent uplink frequency point to ensure that the communication ground station can simultaneously transmit data to the satellite through multiple beams. This invention avoids inter-beam interference by allocating an independent frequency point to each beam, while simultaneously improving transmission reliability through spatial diversity. It ensures that each communication ground station, regardless of which beam coverage area it is located in, can access the system through its dedicated frequency point.

[0078] The time interval for transmitting frequency-selective frames is a fixed time t, and the duration of the frequency-selective state is 2t.

[0079] 2. The satellite transparently forwards the selected frequency frame to the corresponding beam.

[0080] The transparent relay satellite transparently relays the uplink frequency-selective frame sent by the ground communication station to downlink beams in different geographical locations based on the radio frequency point of the frame. This relay process only amplifies and converts the signal; no receiving processing is performed.

[0081] 3. The communication terminal receives the frequency selection frame and determines the beam coverage.

[0082] After startup, the communication terminal enters a frequency selection state, which lasts for 2 seconds. During this state, the terminal acquires all possible downlink frequencies of satellites with selectable frames. This acquisition uses the same symbol rate, coding rate, and coding method as the ground station. After frequency selection, the terminal confirms the frequency of the overlapping beams covering it based on the successfully acquired beams from the selected state.

[0083] 4. The communication terminal uses overlapping beams to send service frames to the satellite.

[0084] The communication terminal uses specific spreading codes, symbol rates, transmission power, coding rates, and coding methods to synchronously transmit service frames to the satellite on all available frequency points, based on all frequency points known under the frequency selection state.

[0085] The structure of the sent service frames is as follows: Figure 4 As shown, it requires the pilot header, frame synchronization header, service segment, and data segment (i.e., ...) necessary for communication reception. Figure 4 (Communication data in the middle).

[0086] The pilot header, as the starting part of the service frame, is formed by spreading a 32-chip sequence of all 1s using Gold code. It is specifically designed for rapid signal acquisition, enabling the communication terminal to complete carrier frequency synchronization and initial timing synchronization in a short time, while accurately estimating channel characteristics. The frame synchronization header uses 13-bit Barker code secondary spreading technology to form a unique 64-chip identifier, ensuring that the receiver can achieve sub-chip-level timing synchronization through sliding correlation acquisition and early-late gate tracking loops. The service segment contains 16 bits of critical control information. The first 8 bits use Gray code and direct binary encoding to identify the beam ID and frequency number, respectively, while the last 8 bits use CRC-8 checksum to ensure the reliability of control command transmission. Although the data segment is only filled with a 128-bit sequence of all 0s, it is expanded to 224 chips through (7,4) Hamming code encoding, maintaining frame structure integrity while achieving power spectrum smoothing. This structural design is particularly optimized for multi-beam applications: all beams share the same pilot Gold code but are distinguished by phase offset; the frame synchronization header maintains beam orthogonality through orthogonal rotation; and the service segment explicitly encodes the frequency-beam mapping relationship. It should be noted that the description of the pilot header, frame synchronization header, service segment, and data segment structure here is merely an example, and those skilled in the art can configure it according to actual needs.

[0087] When transmitting service frames on all frequencies, it is required that the output channels of different frequencies be synchronized in time.

[0088] 5. Transparently forward service frames from the satellite to the ground communication station.

[0089] The satellite transparently forwards the uplink service frames sent by the communication terminal to the ground communication station based on the radio frequency point of the uplink service frames. It also forwards service frames from different beam directions according to the corresponding downlink frequencies. This forwarding process only amplifies and converts the signal; it does not perform any receiving processing.

[0090] 6. The ground communication station receives service frames and processes the data.

[0091] The ground communication station determines the beam containing the service frame based on the acquisition results and performs signal processing algorithms such as despreading, cross-entropy reception estimation, frame synchronization, demodulation, and decoding to parse the service frame information. If the parsed data is successfully obtained, communication is successful.

[0092] When the communication ground station needs to send frequency-selective frames, such as Figure 5 As shown, the specific steps are as follows:

[0093] Step 1: Frequency selection frame transmission begins;

[0094] Step 2: Send frequency-selective frames and start the timer, that is, send frequency-selective frames on all beams and start the timer;

[0095] Step 3: Determine whether to continue sending after the timer reaches t. If yes, proceed to step 2; otherwise, proceed to step 4.

[0096] Step 4: Frequency selection frame transmission complete;

[0097] When a communication terminal needs to send a service frame, such as Figure 6 As shown, the specific steps are as follows:

[0098] Step 1: Service frame transmission begins;

[0099] Step 2: Enter frequency selection mode and start the timer;

[0100] Step 3: Determine whether the frame was successfully captured before the timer reaches 2t, i.e., determine whether the frequency-selective frame receiving module captured the frequency-selective frame before the timer reaches 2t. If yes, proceed to step 5; otherwise, proceed to step 4.

[0101] Step 4: Service transmission frequently fails;

[0102] Step 5: The frequency selection frame receiving module transmits frequency point data to the service frame sending module. That is, the frequency selection frame receiving module transmits the frequency point data of the beam to the service frame sending module according to the acquisition result.

[0103] Step 6: The service frame sending module sends service frames, that is, the service frame sending module sends service frames to all frequency points according to the frequency point information;

[0104] Step 7: Service frame sent successfully;

[0105] When the communication ground station needs to receive service frames, such as Figure 7 As shown, the specific steps are as follows:

[0106] Step 1: Service frame reception begins;

[0107] Step 2: The service frame receiving module captures the service frame and performs subsequent data processing; that is, the service frame receiving module confirms the beam in which the service frame is located and processes the corresponding beam information according to the capture result.

[0108] Step 3: Determine whether the data frame was successfully received after data processing. If yes, proceed to step 4; otherwise, proceed to step 5.

[0109] Step 4: Service frame received successfully;

[0110] Step 5: Service frame reception failed.

[0111] Figure 8 This is the second flowchart illustrating the frequency division joint communication method based on overlapping multi-beams provided in this application. This method is applied to a communication ground station, such as... Figure 8 As shown, the method includes the following steps:

[0112] S210. Send frequency selection frames to all beams of the satellite. The frequency selection frames are spread-spectrum all-1 sequences, and the frequency selection frames of different beams are distinguished by different uplink frequency points. Each frequency point corresponds uniquely to a beam.

[0113] The ground communication station sends frequency-selective frames to all beams of the satellite, and the specific process is as follows:

[0114] First, frequency-selective frames are generated. These frames are spread-spectrum sequences of all 1s, which enhance anti-interference capabilities. Next, frequency points are differentiated. Frequency-selective frames for different beams are distinguished by different uplink frequencies, with each frequency uniquely corresponding to a beam, ensuring that signals from different beams do not interfere with each other. The ground communication station transmits the frequency-selective frames to the satellite via the uplink, and the satellite receives and forwards them to the communication terminals covered by each beam.

[0115] S220. Receive the multi-beam joint transmission signal returned by the communication terminal via satellite. The multi-beam joint transmission signal is the same service frame signal synchronously transmitted by the communication terminal on the corresponding frequency points of all overlapping beams.

[0116] After receiving the frequency-selective frame, the communication terminal performs the following operations:

[0117] Signal synchronization: The communication terminal synchronously transmits the same service frame signal on the corresponding frequency points of all overlapping beams to ensure that the signals of each beam are aligned in time.

[0118] Signal transmission: The communication terminal sends the multi-beam joint transmission signal to the satellite via the downlink, and the satellite receives it and forwards it to the communication ground station.

[0119] Ground station reception: The ground station receives multi-beam joint transmission signals via satellite, which contain the same service frame signals from different beams.

[0120] S230. After separating the signals of each beam in the multi-beam joint transmission signal and completing the despreading operation to obtain symbol-level information, the signals are coherently merged by the cross-entropy estimation algorithm to extract effective data information.

[0121] The communication ground station processes the received multi-beam joint transmission signal as follows:

[0122] Signal analysis: The ground communication station uses the frequency point information contained in the frequency selection frame to identify the signal corresponding to each beam.

[0123] Signal separation: By using frequency domain separation technology, signals at different frequency points are separated to extract the service frame signals of each beam.

[0124] Data extraction: The separated signals are demodulated, decoded, and processed to extract valid data information.

[0125] This invention achieves frequency division multiplexing by assigning different frequencies to different beams, significantly improving spectrum utilization. Multiple beams overlapping and covering the same area further increases system capacity, meeting the needs of high-density users. The frequency selection frame uses a spread-spectrum all-1 sequence, enhancing signal anti-interference capabilities and reducing the impact of multipath fading and noise interference. Communication terminals transmit signals synchronously on all overlapping beams, reducing latency differences and improving signal reception quality. Multi-beam joint transmission increases signal coverage and strength, enhancing system capacity. The ground station can dynamically adjust the frequency allocation of each beam according to user distribution and service requirements, optimizing system performance. Satellite beams can dynamically adjust their coverage area to adapt to different service scenarios. By increasing the number of beams or adjusting frequency allocation, system capacity and coverage can be easily expanded.

[0126] In some embodiments, the frame structure of the service frame includes a pilot header, a frame synchronization header, a service segment, and a data segment.

[0127] In some embodiments, the frequency points transmitted by the frequency selection frame include the uplink frequency points of the communication ground station corresponding to all beams.

[0128] In some embodiments, after separating the signals of each beam in the multi-beam joint transmission signal and completing the despreading operation to obtain symbol-level information as described in S230 above, the signals are coherently combined using a cross-entropy estimation algorithm to extract effective data information, including:

[0129] S2301. Separate the beam signals in the received multi-beam joint transmission signal, perform despreading operation on the separated beam signals, and restore the symbol-level information.

[0130] S2302. A cross-entropy estimation algorithm is used to dynamically weight and merge the symbol-level information of the multi-beam signal. The original data sequence with the highest probability is determined through iterative calculation, and effective data information is extracted. The received multi-beam joint transmission signal is a superposition of the signals from each beam, and each beam signal is modulated by a spreading code. Despreading is performed by correlating the locally generated spreading code with the received signal to recover the original symbol-level information.

[0131] The specific steps are as follows: Assuming the received multi-beam joint transmission signal... ,in For the spread spectrum signal of the i-th beam, .right Correlation detection is performed with local synchronization headers P1, P2, and P3 respectively to determine the frame boundaries of each beam. For the spread spectrum signal of each beam (e.g., ... Perform sliding correlation to adjust the phase of the local spreading code C1 to maximize the correlation value, thus obtaining the synchronized local code. Use the synchronized local code to despread S1 and recover the symbol-level information.

[0132] The original data sequence with the highest probability is determined by iteratively calculating the joint probability distribution of multi-beam symbol-level information. The specific steps are as follows:

[0133] 1. Initialization: Initialize the probability distribution model (such as Markov chain or neural network) by taking the symbol-level information of each beam as input.

[0134] 2. Cross-entropy calculation: For the symbol-level information of each beam, the cross-entropy loss between it and the current probability model is calculated using the cross-entropy function. :

[0135]

[0136] in, For the true sign probability, To predict probabilities for the model, For beam indexing, .

[0137] Based on the cross-entropy loss, adjust the probabilistic model parameters (such as weights and biases) to make the model predictions closer to the true distribution. Repeat step 2 until the cross-entropy loss converges or the preset number of iterations is reached.

[0138] 3. Using the optimized model, perform joint decoding on symbol-level information to determine the original data sequence with the highest probability.

[0139] Assuming the received multi-beam joint transmission signal for:

[0140] ;

[0141] in, Let i be the spread spectrum signal of the i-th beam (i=1,2,3). Let i be the amplitude of the i-th beam. Let be the phase of the i-th beam.

[0142] Calculate the joint transmitted signal using an iterative algorithm. and The value of is used to obtain the iteration result. and The merged signal is obtained using the following formula. And determine the original data with the highest probability based on the merging results.

[0143]

[0144] This invention effectively suppresses non-target beam signals and noise interference through despreading, improving the signal-to-noise ratio. By jointly analyzing multi-beam signals, residual interference is further eliminated, improving the accuracy of data analysis. Frequency division multiplexing and joint analysis enhance spectrum utilization, supporting simultaneous communication by more users. The cross-entropy estimation algorithm dynamically adjusts model parameters according to channel conditions, adapting to different communication environments.

[0145] The frequency division joint communication method based on overlapping multibeams applied to communication ground stations can be referred to and corresponded to the frequency division joint communication method based on overlapping multibeams applied to communication terminals described above. Where there is overlap, it will not be repeated.

[0146] The frequency division joint communication device based on overlapping multibeams provided by the present invention will be described below. The frequency division joint communication device based on overlapping multibeams described below and the frequency division joint communication method based on overlapping multibeams described above can be referred to in correspondence.

[0147] The frequency division joint communication device based on overlapping multi-beams provided by this invention refers to... Figure 9 As shown, it includes a multi-beam service transmission unit located on the communication terminal and a multi-beam service reception unit located on the communication ground station, both of which operate in full-duplex mode.

[0148] The multi-beam service transmission unit includes a frequency-selective frame receiving module and a service frame transmission module that operate in parallel and are connected to each other:

[0149] The frequency selection frame receiving module is used to receive frequency selection frames relayed by the communication ground station via satellite. The frequency selection frames are spread-spectrum all-1 sequences, and the frequency selection frames of different beams are distinguished by different uplink frequency points, with each frequency point uniquely corresponding to a beam. The module also captures the frequency selection frames sent by the communication ground station in the frequency selection state and determines all overlapping beams in which the communication terminal is located based on the frequency selection frame capture results.

[0150] The service frame transmission module is used to frame the signal to be transmitted into service frames, and synchronously transmit the service frames on the corresponding frequency points of all the determined overlapping beams through multi-beam joint modulation to form a multi-beam joint transmission signal; and transparently forward the multi-beam joint transmission signal to the communication ground station through the satellite.

[0151] The frequency selection frame receiving module is used to receive the frequency selection frame sent by the communication ground station. It can perform a full traversal search for possible beam frequency points that may exist in the communication terminal. After the frequency selection is completed, it can be used to send a service frame based on the frequency selection result. The service frame sending module is used to generate and send a multi-beam joint transmission signal. After the signal is sent, it can continue to send subsequent services.

[0152] The multi-beam service receiving unit includes a service frame receiving module and a frequency-selective frame transmitting module that operate in parallel and are connected to each other:

[0153] The frequency selection frame transmission module is used to transmit frequency selection frames to all beams of the satellite. The frequency selection frame is a spread spectrum sequence of all 1s, and the frequency selection frames of different beams are distinguished by different uplink frequency points. Each frequency point corresponds uniquely to a beam.

[0154] The service frame receiving module is used to receive the multi-beam joint transmission signal returned by the communication terminal via satellite. The multi-beam joint transmission signal is the same service frame signal synchronously transmitted by the communication terminal on the corresponding frequency points of all overlapping beams. After separating the beam signals in the multi-beam joint transmission signal and completing the despreading operation to obtain symbol-level information, the module coherently merges the signals using a cross-entropy estimation algorithm to extract effective data information.

[0155] The frequency selection frame sending module is used to send the frequency selection frame used by the communication terminal for frequency selection. The communication ground station sends frequency selection frames of the same format to all beams at fixed intervals of time t. The service frame receiving module is used to receive the service frames transmitted by the communication terminal, confirm the beam in which the frame is located based on the service frame capture result, obtain symbol-level information through despreading, and then use the cross-entropy estimation algorithm to separate and parse the merged beam information to obtain effective data information.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A frequency division joint communication method based on overlapping multi-beams, applied to a communication terminal, characterized in that, include: The receiver receives frequency selection frames relayed by the ground station via satellite. The frequency selection frames are spread-spectrum all-1 sequences, and the frequency selection frames of different beams are distinguished by different uplink frequency points. Each frequency point corresponds uniquely to a beam. In frequency-selective mode, capture the frequency-selective frames sent by the communication ground station, and determine all overlapping beams in which the communication terminal is located based on the frequency-selective frame capture results; The signal to be transmitted is framed to generate a service frame. The service frame is then synchronously transmitted on the corresponding frequency points of all the determined overlapping beams through multi-beam joint modulation to form a multi-beam joint transmission signal. The multi-beam joint transmission signal is transparently forwarded to the communication ground station via satellite. The communication ground station separates the signals of each beam in the multi-beam joint transmission signal and completes the despreading operation to obtain symbol-level information. Then, the symbol-level information is coherently merged using the cross-entropy estimation algorithm to determine the original data sequence with the highest probability.

2. The frequency division joint communication method based on overlapping multi-beams according to claim 1, characterized in that, In frequency selection mode, the communication terminal captures all satellite downlink frequency points that may have frequency selection frames. The frequency selection frame capture process uses the same symbol rate, coding rate and coding method as the communication ground station.

3. The frequency division joint communication method based on overlapping multi-beams according to claim 1, characterized in that, The frame structure of the service frame includes a pilot header, a frame synchronization header, a service segment, and a data segment.

4. The frequency division joint communication method based on overlapping multi-beams according to claim 1, characterized in that, The frequency points transmitted by the frequency selection frame include the uplink frequency points of the communication ground station corresponding to all beams.

5. The frequency division joint communication method based on overlapping multi-beams according to claim 1, characterized in that, The time interval for transmitting frequency-selective frames is a fixed time t, and the duration of the frequency-selective state is 2t.

6. A frequency division joint communication method based on overlapping multibeams, applied to a communication ground station, characterized in that, include: Frequency selection frames are sent to all beams of the satellite. The frequency selection frames are spread-spectrum all-1 sequences, and the frequency selection frames of different beams are distinguished by different uplink frequency points. Each frequency point corresponds uniquely to a beam. The satellite receives the multi-beam joint transmission signal returned by the communication terminal. The multi-beam joint transmission signal is the same service frame signal synchronously transmitted by the communication terminal on the corresponding frequency points of all overlapping beams. After separating the signals of each beam in the multi-beam joint transmission signal and completing the despreading operation to obtain symbol-level information, the symbol-level information is coherently merged through the cross-entropy estimation algorithm to determine the original data sequence with the highest probability.

7. The frequency division joint communication method based on overlapping multi-beams according to claim 6, characterized in that, The frame structure of the service frame includes a pilot header, a frame synchronization header, a service segment, and a data segment.

8. The frequency division joint communication method based on overlapping multi-beams according to claim 6, characterized in that, The frequency points transmitted by the frequency selection frame include the uplink frequency points of the communication ground station corresponding to all beams.

9. The frequency division joint communication method based on overlapping multi-beams according to claim 6, characterized in that, After separating and despreading the signals of each beam in the multi-beam joint transmission signal to obtain symbol-level information, the symbol-level information is coherently merged using a cross-entropy estimation algorithm to determine the original data sequence with the highest probability, including: The signals of each beam in the received multi-beam joint transmission signal are separated, and the separated beam signals are despread to recover the symbol-level information. A cross-entropy estimation algorithm is used to dynamically weight and merge the symbol-level information of multiple beams, and the original data sequence with the highest probability is determined through iterative calculation.

10. A frequency division joint communication device based on overlapping multibeams, characterized in that, It includes a multi-beam service transmission unit located on the communication terminal and a multi-beam service reception unit located on the communication ground station; The multi-beam service transmission unit includes a frequency-selective frame receiving module and a service frame transmission module that operate in parallel and are connected to each other: The frequency selection frame receiving module is used to receive frequency selection frames relayed by the communication ground station via satellite. The frequency selection frames are spread-spectrum all-1 sequences, and the frequency selection frames of different beams are distinguished by different uplink frequency points, with each frequency point uniquely corresponding to a beam. The module also captures the frequency selection frames sent by the communication ground station in the frequency selection state and determines all overlapping beams in which the communication terminal is located based on the frequency selection frame capture results. The service frame transmission module is used to frame the signal to be transmitted into service frames, and synchronously transmit the service frames on the corresponding frequency points of all determined overlapping beams through multi-beam joint modulation to form a multi-beam joint transmission signal; and transparently forward the multi-beam joint transmission signal to the communication ground station through the satellite. The multi-beam service receiving unit includes a service frame receiving module and a frequency-selective frame transmitting module that operate in parallel and are connected to each other: The frequency selection frame transmission module is used to transmit frequency selection frames to all beams of the satellite. The frequency selection frame is a spread spectrum sequence of all 1s, and the frequency selection frames of different beams are distinguished by different uplink frequency points. Each frequency point corresponds uniquely to a beam. The service frame receiving module is used to receive the multi-beam joint transmission signal returned by the communication terminal via satellite. The multi-beam joint transmission signal is the same service frame signal synchronously transmitted by the communication terminal on the corresponding frequency points of all overlapping beams. After separating the beam signals in the multi-beam joint transmission signal and completing the despreading operation to obtain symbol-level information, the module coherently merges the symbol-level information through the cross-entropy estimation algorithm to determine the original data sequence with the highest probability.

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