A multi-dimensional high-spread spectrum ratio low-speed burst signal design method

Abstract

The present application relates to the field of low-speed burst communication signal design in satellite communication, and particularly relates to a multi-dimensional high-spread spectrum ratio low-speed burst signal design method, which utilizes pilot sequences to realize signal acquisition and spread spectrum code word synchronization, utilizes good autocorrelation and cross-correlation characteristics of unique words to identify signal frame types, utilizes high-spread spectrum ratio to reduce signal spectral density, and utilizes multi-dimensional spread spectrum to improve signal anti-interception performance. Pilot, unique word multiplexing coding, interleaved burst service data form a burst signal frame structure, and after multi-dimensional spread spectrum modulation, a transmission signal is formed, which is particularly suitable for satellite communication systems supporting platforms with high concealment requirements. The present application solves the problem of high-spread spectrum ratio low-speed burst signal design and improves the signal anti-interception performance by utilizing multi-dimensional spread spectrum.

Description

Technical Field

[0001] This invention relates to the field of low-speed burst communication signal design in satellite communication, and particularly to a multi-dimensional high spread ratio low-speed burst signal design method, which is especially suitable for satellite communication systems that support platforms with signal concealment requirements. Background Technology

[0002] Multidimensional high spread ratio low-speed burst signal design is a key technology for ensuring communication security on platforms with covert requirements. It forms the foundation and basis for achieving high performance in satellite communication systems using this system. A well-designed burst signal ensures rapid acquisition of the burst signal and the realization of system performance, thus achieving efficient and reliable system operation from the signal design level. Summary of the Invention

[0003] To achieve the design of low-spectrum-density burst communication signals in satellite communications, this invention provides a novel method for designing variable-rate, multi-dimensional, high-spread-ratio, low-speed burst signals. This method solves the problems of processing and transmitting frame structure design for variable-rate, multi-dimensional, high-spread-ratio, low-speed burst signals, and expands the satellite communication system's support capability for platforms with covert requirements.

[0004] The technical solution adopted in this invention is as follows:

[0005] A method for designing multidimensional high spread ratio low-speed burst signals includes the following steps:

[0006] (1) Receive the data to be transmitted, divide the data into N segments according to a predetermined rule, insert the N segments into the frame type and perform channel coding to form N coded data blocks; where 2≤N≤4;

[0007] (2) Select the unique word length according to the system's signal-to-noise ratio and design unique words for the I and Q frame headers;

[0008] (3) Multiplex the N coded data blocks according to the pilot, frame header unique word and coded data block respectively to form N I-channel and Q-channel baseband frame signals;

[0009] (4) Spread the N I-channel and Q-channel baseband frame signals respectively to form N I-channel and Q-channel spread spectrum baseband frame signals;

[0010] (5) Shape filtering is performed on the N I-channel and Q-channel spread spectrum baseband frame signals respectively to form N I-channel and Q-channel transmission frame signals;

[0011] (6) The N I-channel and Q-channel transmission frame signals obtained by shaping filtering are quadrature modulated to form N modulation carriers;

[0012] Complete the design of a multidimensional high spread ratio low-speed burst signal.

[0013] Furthermore, in step (2), a unique word is selected based on the system's signal-to-noise ratio. Specifically, the length of the unique word is determined based on the system's signal-to-noise ratio, and the cross-correlation value between the unique word and other code words and random numbers in the code group is less than one-eighth of the autocorrelation value.

[0014] Furthermore, in step (3), the pilot uses an all-1 sequence, and the pilot length is less than one-tenth of the frame length, and is only used for signal detection and codeword synchronization.

[0015] Furthermore, in step (4), the spreading code adopts the gold sequence, the highest spreading ratio is not less than 32768, and the highest spreading gain is higher than 45dB.

[0016] Furthermore, in step (5), the shaping filter adopts a square root raised cosine filter with a shaping coefficient of 0.15.

[0017] Furthermore, in step (6), the N carrier frequency points are set independently.

[0018] The advantages of this invention compared to the prior art are as follows:

[0019] (1) This invention solves the design problem of high spread spectrum ratio low speed burst signal, uses pilot sequence to realize signal acquisition and spread spectrum code word synchronization, uses the good autocorrelation and cross-correlation characteristics of unique words to identify signal frames, uses high spread spectrum ratio to reduce signal spectral density, and uses multi-dimensional spread spectrum to improve signal anti-interception performance.

[0020] (2) The I and Q signals of this invention use different unique words to correct phase ambiguity.

[0021] (3) The forming factor of this invention is 0.15, which reduces the signal bandwidth and ensures the realization of a high spread ratio. Detailed Implementation

[0022] A method for designing multidimensional high spread ratio low-speed burst signals includes the following steps:

[0023] (1) First, the signal segmentation module receives the data to be transmitted, divides the data into N segments (2≤N≤4) according to a predetermined rule, inserts the N segments of data into the frame type and performs channel coding to form N coded data blocks;

[0024] The channel coding rate is 1 / 2, 1 / 3, or 1 / 4.

[0025] (2) Select the unique word length according to the system's signal-to-noise ratio, and design unique words for the I and Q frame headers for data recovery;

[0026] The system's signal-to-noise ratio (SNR) determines the length of the unique word, which is determined by the channel coding and modulation scheme. The unique word exhibits good cross-correlation characteristics with other codewords and random numbers in the code group, with the cross-correlation value being less than one-eighth of the autocorrelation value.

[0027] (3) Framing: The N coded data blocks output by the signal segmentation module are multiplexed according to the pilot, frame header unique word and coded data block respectively to form N I-channel and Q-channel baseband frame signals;

[0028] The pilot signals use an all-1 sequence, and the pilot signal length is less than one-tenth of the frame length. They are used only for signal detection and codeword synchronization.

[0029] (4) Spread spectrum: Spread the N I-channel and Q-channel baseband frame signals respectively to form N I-channel and Q-channel spread spectrum baseband frame signals;

[0030] The spreading code uses a gold sequence, with a maximum spreading ratio of not less than 32768 and a maximum spreading gain of more than 45dB.

[0031] (5) Shaping filtering: Shaping filtering is performed on N I-channel and Q-channel spread spectrum baseband frame signals respectively to form N I-channel and Q-channel transmission frame signals;

[0032] The shaping filter uses a square root raised cosine filter with a shaping coefficient of 0.15.

[0033] (6) Modulation: The N I-channel and Q-channel transmission frame signals output by the shaping filter are orthogonally modulated to form N modulation carriers, and the N carrier frequency points can be set independently.

[0034] Complete the design of a multidimensional high spread ratio low-speed burst signal.

Claims

1. A method for designing a multidimensional high spread spectrum ratio low-speed burst signal, characterized in that, Including the following steps: (1) Receive the data to be transmitted, divide the data into N segments according to a predetermined rule, insert the N segments into the frame type and then perform channel coding to form N coded data blocks; where 2≤N≤4; (2) Select the unique word length according to the system's signal-to-noise ratio and design the unique words for the I and Q frame headers; (3) Multiplex the N coded data blocks according to the pilot, frame header unique word and coded data block respectively to form N I-channel and Q-channel baseband frame signals; (4) Spread the N I-channel and Q-channel baseband frame signals respectively to form N I-channel and Q-channel spread spectrum baseband frame signals; (5) Shape filtering is performed on the N I-channel and Q-channel spread spectrum baseband frame signals respectively to form N I-channel and Q-channel transmission frame signals; (6) The N I-channel and Q-channel transmission frame signals obtained by shaping filtering are orthogonally modulated to form N modulation carriers; Complete the design of a multidimensional high spread ratio low-speed burst signal; In step (2), the unique word is selected based on the system signal-to-noise ratio. Specifically, the length of the unique word is determined based on the system signal-to-noise ratio, and the cross-correlation value between the unique word and other code words and random numbers in the code group is less than one-eighth of the autocorrelation value. In step (4), the spreading code uses the gold sequence, the maximum spreading ratio is not less than 32768, and the maximum spreading gain is higher than 45dB.

2. The design method for a multidimensional high spread spectrum ratio low-speed burst signal according to claim 1, characterized in that, In step (3), the pilot uses an all-1 sequence and the pilot length is less than one-tenth of the frame length.

3. The design method for a multidimensional high spread spectrum ratio low-speed burst signal according to claim 1, characterized in that, In step (5), the shaping filter uses a square root raised cosine filter with a shaping coefficient of 0.

15.

4. The design method for a multidimensional high spread spectrum ratio low-speed burst signal according to claim 1, characterized in that, In step (6), the N carrier frequency points are set independently.