Communication and conduction integrated navigation information broadcasting method suitable for long navigation message

Abstract

The invention discloses a communication and conduction integrated navigation information broadcasting method suitable for a long navigation message. The method comprises the following steps: (1) injecting a navigation enhancement message to be broadcasted to a satellite from the ground; (2) the satellite processes the uploaded navigation enhancement message to generate a navigation message frame; (3) carrying out interleaving processing on the navigation message frames to form navigation message subframes; (4) performing CRC-x verification on the navigation message subframes; (5) carrying out 1 / 2 LDPC error correction coding on the navigation message sub-frame after the CRC-x verification; and (6) broadcasting the navigation message after the LDPC error correction coding and the communication signal at the same time, adopting the same waveform and occupying different bandwidth resources. The broadcasting method provided by the invention solves the problem of low frame splicing success rate of the long telegraph text.

Description

Technical Field The invention relates to a communication and navigation integrated navigation information broadcasting method applicable to a long navigation message, belonging to the technical field of satellite communication and navigation fusion. Background Art Satellite navigation systems can provide global coverage, low-cost, high-precision space-time services, and have become the foundation and core of international space-time information services. Satellite navigation systems have inherent problems: the navigation signals broadcast by medium and high-orbit satellites are transmitted over tens of thousands of kilometers, with low landing levels, and are easily blocked by trees and buildings, and are also easily affected by other communication systems or even malicious interference. With satellite navigation systems as the core and supplemented by other means, providing space-time services with wider coverage, higher precision, and more robustness has become a consensus in the current international space-time technology field. The low-orbit satellite communication system has the characteristics of high signal landing level, fast geometric configuration change and wide coverage. It relies on the satellite communication network to supplement, backup and enhance the satellite navigation system, showing significant synergy advantages. On the one hand, it can directly broadcast navigation signals through the communication system and jointly locate with the navigation system to achieve better navigation signal coverage; on the other hand, it can transmit auxiliary information through the communication link to achieve rapid sub-meter positioning on a global scale. Satellite communication and navigation fusion refers to the integration of communication and navigation systems through multi-level integrated design of signals, information, platforms, networks, etc., to achieve coordination and enhancement of communication and navigation business capabilities. Its technical connotation spans the two major fields of communication and navigation, and belongs to the category of emerging interdisciplinary subjects. Currently, the main technical directions reported are signal design of communication and navigation fusion [1-3], communication and navigation fusion channel model [4-7], and communication and navigation fusion network architecture [8-11]. The related system is Iridium II. There are no reports on navigation information enhancement methods based on low-orbit constellation communication systems.

[0001] Tang Guomin, Communication and navigation integrated signal design based on low-orbit satellite[D], University of Electronic Science and Technology of China, 2022.

[0002] DengZ,YuY,YuanX,etal.Situationanddevelopmenttendencyofindoorpositioning[J].ChinaCommunications,2013,10(3):42-55.

[0003] Wu Di. Research on UWB indoor positioning and communication integrated technology[D]. Harbin: Harbin Engineering University, 2018.

[0004] LooC.Astatisticalmodelforalandmobilesatellitelink[J].IEEETransactiononVehicularTechnology,1985,34(3):122-127.

[0005] Corazza GE, Vatalaro F. Astatistical model for land mobile satellite channels and its application to nongeo stationary orbit systems [J]. IEEE Transactions on Vehicular Technology, 1994, 43(3): 738-742.

[0006] Suzuki H.Astatistical model for urban radio propagation[J].IEEETransaction on Communication,1977,25(7):673-680.

[0007] LutzE, CyganD, DippoldM, et al. The land mobile satellite communication channel-recording, statistics, and channel model [J]. IEEE Transactions on Vehicular Technology, 1991, 40(2): 375-386.

[0008] Cui Songzuo, Wei Baoguo, Bao Yachuan. Compatibility analysis of integrated OFDM and UWB communication and positioning system in indoor environment[J]. Electronic Measurement Technology, 2021, 44(18): 160-166.

[0009] Ouyang Jun, Chen Shijun, Huang Xiaoming, et al. Analysis of high-precision positioning technology for 5G mobile communication network[J]. Mobile Communications, 2019, 43(9): 13-17.

[0010] Zheng Zuoya, Xue Qinghao, Qiu Linyao, et al. Discussion on the application of integrated space-ground communication, navigation and remote sensing based on network information system thinking[J]. Journal of China Academy of Electronics Science, 2020, 15(8): 709-714.

[0011] Research progress on the conceptual framework and key technologies of integrated communication and navigation, Wei Baoguo et al., Navigation Positioning and Timing, 2022, 5, (9)2. Summary of the invention The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, to provide a navigation information broadcasting method for integrated communication and navigation suitable for long navigation messages, and to solve the problem of low success rate of long message frame splicing. The technical solution of the present invention is: A method for broadcasting navigation information integrated with communication and navigation applicable to a long navigation message comprises the following steps: (1) The navigation augmentation message to be broadcasted is sent from the ground to the satellite; (2) The satellite processes the navigation augmentation message and generates a navigation message frame; (3) Interleaving the navigation message frames to form navigation message subframes; (4) Perform CRC-x check on the navigation message subframe; (5) Perform 1 / 2 LDPC error correction coding on the navigation message subframe after CRC-x check; (6) The navigation message after LDPC error correction coding is broadcast simultaneously with the communication signal, using the same waveform but occupying different bandwidth resources. Furthermore, the satellite processes the navigation enhancement message to generate a navigation message frame, specifically: Assuming that the number of navigation enhancement messages to be broadcast within a certain period of time is a bit, the satellite combines the navigation enhancement message a bit with the intra-time round-robin count b bit to form an (a+b) bit message, i.e., one navigation message frame. Further, let a+b=m×n, wherein n refers to the number of navigation message subframes formed after interleaving, and m refers to the m-bit message broadcasted in each subframe after interleaving. Furthermore, the intra-hour round-robin count refers to the number of times the same navigation enhancement message is broadcast within one hour. Furthermore, the interleaving process of the navigation message frame to form the navigation message subframe is specifically as follows: The (a+b) bit message is interleaved m×n to form n navigation message subframes, and each subframe broadcasts m parameters; The interleaving means dividing the data into blocks at the transmitting end and arranging different bits in the same block of data in a dispersed and staggered manner, so that the probability of data bit errors occurring during transmission in the channel becomes more uniform. Furthermore, the CRC-x check is performed on the navigation message subframe, specifically: Perform CRC-x check on the m-bit message, c-bit subframe number, and d-bit 5ms count to form a message parameter of (m+c+d+x) bits; x refers to the length of the cyclic redundancy check code. The intra-hour 5ms count refers to: the nth 5ms in 1 hour. Furthermore, the 1 / 2 LDPC error correction coding is performed on the navigation message subframe after the CRC-x check, specifically: The (m+c+d+x)-bit message parameters are coded with 1 / 2 LDPC to form the error-correcting coded symbol 2×(m+c+d+x)-bit, which together with the e-bit frame header form a navigation subframe (2×(m+c+d+x)+e)-bit. Furthermore, the navigation message after the LDPC error correction coding is broadcasted simultaneously with the communication signal, using the same waveform, specifically: The navigation message after LDPC error correction coding is first spread spectrum modulated to generate a spread spectrum sequence, and then BPSK modulated to generate a complex-valued modulation signal. It is then unified with the communication modulation signal for IFFT to generate OFDM symbols, and the CP is added to generate a time domain baseband waveform. The navigation signal and the communication signal are broadcast simultaneously. In a second aspect, the present invention further proposes a non-volatile storage medium, comprising: a computer program product, which executes the method when the computer program product is executed. In a third aspect, the present invention further proposes a computer program product, which implements the method when executed by a processor. The beneficial effects of the present invention compared with the prior art are: (1) A navigation information broadcasting method suitable for long navigation messages was designed. (2) A method of splitting long-frame messages and encoding short-frame messages was designed. By decoupling the subframes and increasing the verification of the frame structure, the success rate of long-frame message reception was improved. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart of the method of the present invention; Figure 2 A schematic diagram of the navigation augmentation message being uploaded from the ground to the satellite; Figure 3 A schematic diagram of the process of generating and broadcasting navigation messages; Figure 4 This is a schematic diagram of the navigation message frame format. DETAILED DESCRIPTION The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings. In the communication and navigation fusion system, there is a problem that the communication channel capacity is limited, and the navigation message is too long to be broadcast at one time. It is necessary to divide the complete navigation message frame into subframes that match the channel capacity for broadcasting. The terminal side receives the subframes one by one, and then splices the frames to decode the complete message. If a subframe is lost or a subframe has an error and is discarded, the message cannot be successfully spliced ​​and decoded. The present invention proposes a communication and navigation integrated navigation information broadcasting method suitable for long navigation messages, which solves the problem of low success rate of splicing long messages. The solution of the present invention adopts the method of first dividing the subframes and then performing LDPC error correction coding on the subframes, which can improve the success rate of frame splicing and increase the protection of frame header information. Figure 1 shown. The present invention proposes a method for broadcasting navigation information integrated with communication and navigation applicable to a long navigation message, comprising the following steps: (1) The navigation augmentation messages to be broadcasted within a certain period of time are sent from the ground to the satellite, such as Figure 2 shown. (2) The satellite processes the navigation augmentation message and generates a navigation message frame; specifically: Assuming that the number of navigation enhancement messages to be broadcast within a certain period of time is a bit, the satellite combines the navigation enhancement message a bit with the intra-time round-robin count b bit to form an (a+b) bit message, i.e., one navigation message frame. Let a+b=m×n, where n refers to the number of navigation message subframes formed after interleaving, and m refers to the m-bit message broadcast in each subframe after interleaving. The intra-hour round-robin count refers to the number of times the same navigation enhancement message is broadcast within one hour. (3) Interleaving the navigation message frame to form a navigation message subframe; specifically: The (a+b) bit message is interleaved m×n to form n navigation message subframes, and each subframe broadcasts m parameters; The interleaving means dividing the data into blocks at the transmitting end and arranging different bits in the same block of data in a dispersed and staggered manner, so that the probability of data bit errors occurring during transmission in the channel becomes more uniform. (4) Perform CRC-x check on the navigation message subframe; Perform CRC-x check on the m-bit message, c-bit subframe number, and d-bit 5ms count to form a message parameter of (m+c+d+x) bits; x refers to the length of the cyclic redundancy check code. The intra-hour 5ms count refers to: the nth 5ms in 1 hour. (5) Perform 1 / 2 LDPC error correction coding on the navigation message subframe after CRC-x check; specifically: The (m+c+d+x)-bit message parameters are coded with 1 / 2 LDPC to form the error-correcting coded symbol 2×(m+c+d+x)-bit, which together with the e-bit frame header form a navigation subframe (2×(m+c+d+x)+e)-bit. (6) The navigation message after LDPC error correction coding is broadcast simultaneously with the communication signal, using the same waveform but occupying different bandwidth resources. The navigation message after LDPC error correction coding is first spread spectrum modulated to generate a spread spectrum sequence, and then BPSK modulated to generate a complex-valued modulation signal. It is then unified with the communication modulation signal for IFFT to generate OFDM symbols, and the CP is added to generate a time domain baseband waveform. The navigation signal and the communication signal are broadcast simultaneously. Example: 1. Assume that the length of the navigation message to be broadcast is 728 bits, which is uploaded to the satellite by the ground-based space-time information processing system. 2. The 728-bit navigation message and the 12-bit time cycle count together form a 740-bit message parameter. 3. After 74×10 interleaving, each navigation subframe broadcasts 74 parameters, for a total of 10 subframes. 4. The 74-bit message parameters, the 4-bit navigation subframe number, and the 20-bit 5ms count are checked by CRC-8, forming a total of 106-bit message parameters before error correction coding. 5. The 106-bit message parameters are coded with 1 / 2 LDPC (106, 212) error correction to form 212 error correction coded symbols, which together with the 16-bit frame header (0xEB90, i.e. 1110 1011 1001 0000) form a 228-bit navigation subframe. 6. The navigation subframe is first spread spectrum modulated to generate a spread spectrum sequence, then BPSK modulated to generate a complex valued modulation signal, and then IFFT is performed with the communication modulation signal to generate OFDM symbols, and the time domain baseband waveform is generated after adding CP. The navigation signal and the communication signal are broadcast simultaneously on the 5ms wave position. (CP: cyclic prefix) Navigation message generation and broadcasting process implementation example Figure 3 , the navigation message frame format is implemented as follows Figure 4 . The advantage of this method is that different message subframes are decoupled. If a subframe is lost due to factors such as changes in the quality of the satellite-to-ground link, it can be replaced by a subframe with the same sequence number in the next round of broadcasting. It is only necessary to add a new navigation message to the ground-based space-time information processing system before sending it to the satellite. By broadcasting 10 message subframes in multiple rounds, the long message frame can be decoded. Compared with the need to collect 1 to 10 consecutive subframes to splice and decode the frame, the success rate of splicing is greatly improved. At the same time, the introduction of interleaving makes the probability of bit errors more uniform, which can improve the error correction performance. Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

Claims

1. A navigation information broadcasting method for integrated communication and navigation suitable for long navigation messages, characterized in that include: The navigation augmentation message to be broadcasted is sent from the ground to the satellite; The satellite processes the navigation enhancement message and generates a navigation message frame; Interleaving the navigation message frames to form navigation message subframes; Perform CRC-x check on the navigation message subframe; Perform 1 / 2LDPC error correction coding on the navigation message subframe after CRC-x check; The navigation message after LDPC error correction coding is broadcast simultaneously with the communication signal, using the same waveform but occupying different bandwidth resources.

2. The method for broadcasting navigation information integrated with communication and navigation applicable to long navigation messages according to claim 1, characterized in that: The satellite processes the navigation enhancement message to generate a navigation message frame, which is specifically: Assuming that the number of navigation enhancement messages to be broadcast within a certain period of time is a bit, the satellite combines the navigation enhancement message a bit with the intra-time round-robin count b bit to form an (a+b) bit message, i.e., one navigation message frame.

3. The method for broadcasting navigation information integrated with communication and navigation applicable to long navigation messages according to claim 2, characterized in that: Let a+b=m×n, where n refers to the number of navigation message subframes formed after interleaving, and m refers to the m-bit message broadcast in each subframe after interleaving.

4. The method for broadcasting navigation information integrated with communication and navigation applicable to long navigation messages according to claim 2, characterized in that: The intra-hour round-robin count refers to the number of times the same navigation enhancement message is broadcast within one hour.

5. The method for broadcasting navigation information integrated with communication and navigation applicable to long navigation messages according to claim 3, characterized in that: The interleaving process of the navigation message frame to form the navigation message subframe is specifically as follows: The (a+b) bit message is interleaved m×n to form n navigation message subframes, and each subframe broadcasts m parameters; The interleaving means dividing the data into blocks at the transmitting end and arranging different bits in the same block of data in a dispersed and staggered manner, so that the probability of data bit errors occurring during transmission in the channel becomes more uniform.

6. The method for broadcasting navigation information integrated with communication and navigation applicable to long navigation messages according to claim 5, characterized in that: The CRC-x check is performed on the navigation message subframe, specifically: Perform CRC-x check on the m-bit message, c-bit subframe number, and d-bit 5ms count to form a message parameter of (m+c+d+x) bits; x refers to the length of the cyclic redundancy check code. The intra-hour 5ms count refers to: the nth 5ms in 1 hour.

7. The method for broadcasting navigation information integrated with communication and navigation applicable to long navigation messages according to claim 6, characterized in that: The 1 / 2 LDPC error correction coding is performed on the navigation message subframe after the CRC-x check, specifically: The (m+c+d+x)-bit message parameters are coded with 1 / 2 LDPC to form the error-correcting coded symbol 2×(m+c+d+x)-bit, which together with the e-bit frame header form a navigation subframe (2×(m+c+d+x)+e)-bit.

8. The method for broadcasting navigation information integrated with communication and navigation applicable to long navigation messages according to claim 7, characterized in that: The navigation message after LDPC error correction coding is broadcasted simultaneously with the communication signal, using the same waveform, specifically: The navigation message after LDPC error correction coding is first spread spectrum modulated to generate a spread spectrum sequence, and then BPSK modulated to generate a complex-valued modulation signal. It is then unified with the communication modulation signal for IFFT to generate OFDM symbols, and the CP is added to generate a time domain baseband waveform. The navigation signal and the communication signal are broadcast simultaneously.

9. A non-volatile storage medium, characterized in that: include: A computer program product, when the computer program product is executed, performs the method according to any one of claims 1 to 7.

10. A computer program product, characterized in that When the computer program product is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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