Lunar surface communication time synchronization and positioning method based on codebook

Abstract

The invention discloses a lunar surface communication time synchronization and positioning method based on a codebook, and belongs to the technical field of deep space exploration. The method comprises the following steps: the lunar surface base station analyzes a coverage area, establishes a base station beamforming codebook, and sends a pilot signal according to the codebook at a fixed time interval; the lunar surface user receives the pilot signal, selects a codebook with the strongest power according to the strength of the pilot signal, calculates the own delay, and feeds the own delay and the strongest codebook back to the lunar surface base station; and the lunar surface base station determines the position of the lunar surface user according to the feedback information of the lunar surface user so as to realize the positioning of the lunar surface user. The method does not need to establish a lunar space-time reference through a relay satellite or earth navigation system, achieves the relative positioning of the lunar user based on the lunar base station, and can reduce the cost and complexity of lunar communication time synchronization and positioning.

Description

Technical Field

[0001] The present invention belongs to the technical field of deep space exploration, and particularly relates to a method for lunar communication time synchronization and positioning based on a codebook. Background Art

[0002] Subsequent lunar exploration missions have shifted from "scientific discovery and exploration" to "equal emphasis on science and application", which means that there will be more and more detectors, resource collection robots, and even astronauts working on the lunar surface. Therefore, it is urgent to establish a lunar multi-user (Communication Users, CUs) communication system.

[0003] In a lunar multi-CUs communication system, the design of the communication synchronization channel, that is, the design of the time synchronization between the CUs and the base station (Base Station, BS), is an important factor affecting lunar communication performance. This is because only when the BS and the CUs maintain the same time reference can tasks such as the establishment of communication links, the establishment of communication networks, and the selection of communication parameters be completed.

[0004] Another important factor affecting lunar communication performance is the positioning ability of the BS for the CUs. On the lunar surface, the BS needs to have the ability of long-distance communication and a large density of local service CUs. Therefore, the antenna used by the BS is a directional antenna with directivity, so as to provide high-gain communication services in a specific direction and specific area. Therefore, the BS using a directional antenna first needs to obtain the position information of the CUs before it can design the corresponding beam to complete the communication task.

[0005] There are usually two ways to implement time synchronization and positioning services in a terrestrial multi-CUs communication system. One is to design a complex logical channel, such as dividing each communication channel into multiple time frames in the GSM system and using specific several frames to transmit frame synchronization information; the other is to use the GNNS system, such as using the GPS system or the Beidou system to provide positioning information and broadcast time synchronization information.

[0006] The research on time synchronization and positioning services on the lunar surface is currently in its infancy. First, in existing lunar exploration missions, the number of detectors is small, so relay satellites can be used to directly communicate with the detectors to achieve time synchronization and navigation. However, as mentioned above, in the future, more and more CUs will need to work simultaneously on the lunar surface. The relay satellite solution not only has inherent defects such as long communication distance and limited transmission power, but also has technical difficulties such as cumbersome star search process and insufficient coverage, and it is difficult to adapt to the future lunar multi-CUs communication system.

[0007] Since the distribution of resources such as lunar minerals is relatively concentrated, and lunar research stations are only distributed in a small area, future lunar CUs will be concentrated in several small areas, which is very suitable for applying the codebook technology. Currently, the codebook technology has been successfully applied to beamforming tasks in terrestrial 5G mobile communications. By analyzing the service area range, predefining the transmit and receive codebooks, and then selecting the best codebook according to the channel conditions, a low-complexity and low-power consumption link can be established. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides a codebook-based lunar communication time synchronization and positioning method, which realizes the time synchronization between the lunar base station and the user through codebook design, and realizes the positioning of multiple lunar users based on the lunar base station; the lunar base station sequentially sends pilot signals according to the codebook at fixed time intervals, the user judges the received power magnitude, marks the maximum power codeword, records and calculates the delay and feeds back to the base station, and the base station calculates the propagation delay, synchronizes the time, and determines the user position according to the feedback information of the user. The base station allocates communication resources for the user and feeds back the user time synchronization information and position information. The present invention does not need to establish a lunar space-time reference through a relay satellite or a terrestrial navigation system, and realizes the relative positioning of lunar users based on the lunar base station, which can reduce the cost and complexity of lunar communication time synchronization and positioning.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] On the one hand, the present invention provides a codebook-based lunar communication time synchronization and positioning method, which is applied to a single lunar base station and lunar users, and the method includes:

[0011] The lunar base station analyzes the coverage area, establishes a base station beamforming codebook, and sends pilot signals according to the codebook at fixed time intervals;

[0012] The lunar user receives the pilot signal, selects the codebook with the strongest power according to the pilot signal strength, calculates its own delay, and feeds back its own delay and the strongest codebook to the lunar base station;

[0013] The lunar base station determines the position of the lunar user according to the feedback information of the lunar user, and realizes the positioning of the lunar user.

[0014] On the other hand, the present invention provides a codebook-based lunar communication time synchronization and positioning method, which is applied to multiple lunar base stations and lunar users, and the method includes:

[0015] The multiple lunar base stations perform time synchronization between the lunar base stations;

[0016] Each of the multiple lunar base stations analyzes the coverage area, establishes a base station beamforming codebook, and sends pilot signals according to the codebook at fixed time intervals;

[0017] The lunar user receives the pilot signal, selects the codebook with the strongest power according to the pilot signal strength, calculates its own delay, and feeds back its own delay together with the strongest codebook to the corresponding lunar base station;

[0018] The multiple lunar base stations respectively determine the positions of lunar users based on the feedback information of the lunar users. The overlapping area of the multiple lunar user positions determined by the multiple lunar base stations is the final user position information.

[0019] The beneficial effects of the present invention are as follows:

[0020] The present invention establishes a lunar coordinate system based on lunar base stations, without the need for navigation enhancement satellites required for tracing from the Earth or large-aperture navigation receiving antennas required for directly receiving GNSS leakage signals, reducing the system construction and maintenance costs; compared with relying entirely on Earth-orbiting satellites for navigation, lunar base stations can reduce the dependence on Earth facilities for navigation, improving the autonomy and reliability of the system. This is particularly important for long-term stays or long-distance missions; time synchronization and positioning based on the codebook do not require additional navigation broadcast signals and user receiving equipment, truly realizing the integrated design of communication and navigation, reducing the complexity and power consumption of base stations and user terminal equipment; channel analysis and codebook establishment are carried out for complex lunar terrains, and reliable signal coverage is maintained under complex terrain conditions through corresponding beamforming; lunar base stations maintain highly accurate time through equipment such as atomic clocks, and the time transfer error between the base station and the user is greatly reduced compared with long-distance relay transmission from the Earth, thereby improving the performance of the entire system, simplifying the system while ensuring high positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of time synchronization and positioning under a single BS of the present invention;

[0022] Figure 2 It is a schematic diagram of time synchronization and positioning under multiple BSs of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present invention will be further described below with reference to the drawings and embodiments.

[0024] In a first aspect, the present invention provides a method for lunar communication time synchronization and positioning based on a codebook, which is applied to a single lunar base station and lunar users, and realizes time synchronization and user positioning and navigation through a single base station; specifically includes the following steps:

[0025] The lunar base station analyzes the covered area, establishes a base station beamforming codebook, and transmits pilot signals according to the codebook at fixed time intervals;

[0026] The lunar user receives the pilot signal, selects the codebook with the strongest power according to the pilot signal strength, calculates its own delay, and feeds back its own delay and the strongest codebook to the lunar base station;

[0027] The lunar base station determines the position of the lunar user based on the feedback information of the lunar user, and realizes the positioning of the lunar user.

[0028] Furthermore, the lunar base station analyzes information such as the terrain features, building distribution, and user density of the covered area, calculates the simulated channel characteristics, optimizes the antenna pattern, and forms a complete base station beamforming codebook;

[0029] Furthermore, the lunar base station includes: a time reference device, an antenna system, a transceiver, a baseband unit, a monitoring and management system, a power supply system, an environmental control system, etc.; the lunar user includes: a wireless communication module, a central processing unit, a power management module, etc.;

[0030] Furthermore, the time reference device of the lunar base station is an atomic clock, which provides a highly stable time reference for the lunar communication and navigation system;

[0031] Furthermore, the antenna system of the lunar base station is a multi-beam directional scanning antenna, which is used to realize the wireless transmission of time, position, and communication information; the transceiver and the baseband unit realize functions such as the generation and amplification of radio frequency signals, signal modulation and demodulation, encoding and decoding, etc.; the monitoring and management system realizes the management and control of the base station status; the power supply and environmental control system provides energy and environmental guarantees for the base station;

[0032] Furthermore, the wireless communication module of the lunar user includes an omnidirectional antenna and signal amplification equipment, which is convenient for receiving base station signals that may come from any direction and transmitting the transmitted signal to the base station that may be in any direction; the central processing unit realizes functions such as the processing of transmitted and received signals, the calculation of the processing and forwarding delay of received signals, signal modulation and demodulation, encoding and decoding, and time synchronization with the base station; the power management module realizes the energy supply and power supply management of each module of the user;

[0033] Furthermore, the directional antenna of the lunar base station scans and covers the surrounding space at specific time intervals and specific steps. The smaller the step, the denser the grid, and the more accurate the positioning;

[0034] Furthermore, the lunar user selects the most powerful codebook based on received signal strength, synchronizes system time, and sends its calculated delay and the codebook to the base station. Upon receiving the corresponding codebook, the base station calculates the time difference between the base station's transmitted signal and the user's received signal, thereby calculating the user's distance from the base station. The codebook contains azimuth information, enabling user positioning and navigation. As needed, the base station points its directional antenna toward the user based on the codeword sent by the user, establishing a high-speed communication link between the base station and the user.

[0035] Secondly, a codebook-based lunar communication time synchronization and positioning method is provided, which is applied to multiple lunar base stations and lunar users, achieving time synchronization and high-precision positioning and navigation of users through multiple base stations;

[0036] The multiple lunar base stations perform time synchronization among the lunar base stations;

[0037] The process of lunar users communicating with various lunar base stations for positioning is the same as the process of lunar users positioning with a single base station. The overlapping area where multiple base stations determine the position is the user's location information. As the number of base stations increases, the user's positioning accuracy can be greatly improved.

[0038] Example

[0039] The present invention proposes a codebook-based lunar communication time synchronization and positioning method, which takes into account the distribution characteristics of lunar CUs. It is a low-complexity and efficient solution and can be divided into a single-BS solution and a multi-BS solution.

[0040] System diagram reference for single BS solution Figure 1 As shown in the figure, after the coverage area analysis is completed, the BS beamforming codebook can be established. After that, the BS transmits the pilot signal according to the BS beamforming codebook at a specific time interval T, and a meshed spatial position map can be established. The pilot signal period interval is determined by the channel coherence time, the corresponding business requirements and the pilot overhead. Too long an interval will reduce the positioning accuracy, and too short an interval will waste resources. The BS and CUs use the 5G communication frequency band, and the communication frequency fc is selected as 2.4GHz. Assuming that the communication channel is a flat fading channel, according to the Jakes model, the channel coherence time is calculated as follows: , where c is the speed of light and V is the CUs moving speed. To meet the CUs requirements and ensure the accuracy of channel parameter estimation, according to the CUs service delay requirement T latency And the channel coherence time Tc can determine the pilot signal period interval T≤1 / 2 Tc, T≤T latency The lunar surface CUs are mainly for operation robots, lunar rovers and manned missions. The moving speed V is calculated as a maximum of 1km / h. The service delay requirement is T latencyNot less than 1 s, calculated according to the formula , the pilot signal period T is set to 100 ms.

[0041] After the CUs are added, the specific implementation process is as follows:

[0042] Step 1: The BS transmits pilot signals in sequence according to the codebook at a fixed time interval T;

[0043] Step 2: After the CU receives the pilot signals under different codewords, it determines the power of the pilot signals;

[0044] Step 3: The CU determines the codeword with the maximum received power, marks it as the K codeword, and records its own calculation delay;

[0045] Step 4: The CU feeds back the K codeword and its own calculation delay to the base station;

[0046] Step 5: After receiving the feedback from the CU, the BS calculates the propagation delay, synchronizes the time, and determines the user location;

[0047] Step 6: The BS allocates communication resources for the CU and feeds back the CU time synchronization information and location information.

[0048] The communication between the CU and the BS and the positioning of the CU can be realized, providing communication and navigation services for the CU.

[0049] The system schematic diagram of the multi-BS scheme is referred to Figure 2 as shown. First, multiple BSs complete time synchronization and positioning with each other, and then transmit pilot signals at the same time interval and specific shaping codewords.

[0050] After the CUs are added, the specific implementation process is as follows:

[0051] Step 1: Multiple BSs complete time synchronization and positioning with each other and inform each other of the service status;

[0052] Step 2: Multiple BSs transmit their own pilot signals in sequence according to their own codebooks at a fixed time interval T;

[0053] Step 3: After the CU receives the pilot signals under different codewords, it determines the power of the pilot signals;

[0054] Step 4: After the CU receives the pilot signals from different BSs, it determines the pilot codewords K1, K2... Kn with the maximum power for different base stations respectively;

[0055] Step 5: The CU calculates its own position according to the relationship of the pilot codewords, and the CU can determine that its position is in the overlapping area of two single-BS grid positions;

[0056] Step 6: The CU feeds back time synchronization information and location information to the BS, and the BS network determines a suitable serving BS;

[0057] Step 7: The serving BS allocates communication resources for the CU and notifies the CU to establish a communication link.

[0058] The communication between the CU and the BS and the positioning of the CU can be realized, providing communication signal navigation services for the CU.

[0059] The embodiment of the present invention provides a method for lunar communication time synchronization and positioning based on a codebook, which does not need to establish a lunar space-time reference through a relay satellite or an earth navigation system, and realizes relative positioning of lunar users based on a lunar base station, which can reduce the cost and complexity of lunar communication time synchronization and positioning.

[0060] The above specific embodiments have further detailed the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A codebook-based lunar communication time synchronization and positioning method, which is applied to a single lunar base station and lunar users, is characterized in that The method includes: The lunar base station analyzes the coverage area, establishes a base station beamforming codebook, and sends pilot signals according to the codebook at fixed time intervals; The lunar user receives the pilot signal, selects the codebook with the strongest power according to the pilot signal strength, calculates its own delay, and feeds back its own delay and the strongest codebook to the lunar base station; The lunar base station determines the position of the lunar user based on the feedback information of the lunar user, and realizes the positioning of the lunar user.

2. The lunar communication time synchronization and positioning method based on a codebook according to claim 1, wherein The lunar base station analyzes the terrain features, building distribution, and user density of the coverage area, calculates the simulated channel characteristics, optimizes the antenna pattern, and forms a complete base station beamforming codebook.

3. A method for lunar surface communication time synchronization and positioning based on a codebook according to claim 1, characterized in that The lunar base station includes a time reference device, an antenna system, a transceiver, a baseband unit, a monitoring and management system, a power supply system, and an environmental control system; the lunar user includes a wireless communication module, a central processor, and a power management module.

4. A method for lunar surface communication time synchronization and positioning based on a codebook according to claim 3, characterized in that, The time reference device of the lunar base station is an atomic clock.

5. A method for lunar surface communication time synchronization and positioning based on a codebook according to claim 3, characterized in that The antenna system of the lunar base station is a multi-beam directional scanning antenna; the transceiver and the baseband unit are used for the generation and amplification of radio frequency signals, signal modulation and demodulation, encoding and decoding; the monitoring and management system is used for the state management and control of the lunar base station; the power supply and environmental control system is used to provide energy and environmental guarantee for the lunar base station.

6. A method for lunar surface communication time synchronization and positioning based on a codebook according to claim 3, characterized in that The wireless communication module of the lunar user includes an omnidirectional antenna and a signal amplification device; the central processor is used for the processing of transmitted and received signals, calculating the delay of processing and forwarding of received signals, signal modulation and demodulation, encoding and decoding, and realizing time synchronization with the lunar base station; the power management module is used to provide energy and power management for each module of the user.

7. A method for lunar surface communication time synchronization and positioning based on a codebook according to claim 1, characterized in that The directional scanning antenna of the lunar base station scans and covers the surrounding space at fixed time intervals and fixed scanning angles in the codebook.

8. A method for lunar surface communication time synchronization and positioning based on a codebook according to claim 1, characterized in that The lunar user selects the codebook with the strongest power according to the received signal strength, synchronizes the system time, and sends its own calculated delay and the codebook to the lunar base station. The lunar base station receives the corresponding codebook, calculates the time difference between the signal sent by the lunar base station and the signal received by the lunar user, and calculates the distance of the lunar user relative to the lunar base station.

9. A method for lunar surface communication time synchronization and positioning based on a codebook according to claim 8, characterized in that, The codebook includes azimuth information.

10. A codebook-based lunar communication time synchronization and positioning method, applied to multiple lunar base stations and lunar users, characterized in that, The method includes: The multiple lunar base stations perform time synchronization between the lunar base stations; Each of the multiple lunar base stations analyzes the coverage area, establishes a base station beamforming codebook, and sends pilot signals according to the codebook at fixed time intervals; The lunar user receives the pilot signal, selects the codebook with the strongest power according to the pilot signal strength, calculates its own delay, and feeds back its own delay and the strongest codebook to the corresponding lunar base station; The multiple lunar base stations respectively determine the positions of the lunar users based on the feedback information of the lunar users. The overlapping area of the multiple lunar user positions determined by the multiple lunar base stations is the final user position information.

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