Satellite communication navigation fusion multiple access signal design method based on continuous interference cancellation

Abstract

The invention provides a satellite communication navigation fusion multiple access signal design method based on continuous interference elimination. With the increasingly mature continuous interference elimination technology, the anti-interference capability of a satellite navigation signal and the certainty of a pseudorandom sequence used by a navigation satellite are considered at the same time; the technical complexity of simulating and removing positioning signals in received signals through the continuous interference elimination technology is lower than that of layer-by-layer decoding in non-orthogonal multiple access, and it is possible that the continuous interference elimination technology is used for communication navigation fusion waveform design. In order to give play to the advantages of the continuous interference cancellation technology on multiple access, the downlink communication service is provided for a plurality of users by using the same time-frequency resource in combination with a rate splitting multiple access strategy. A communication navigation fusion multiple access scheme is designed by considering the adaptability of a positioning information sequence and a continuous interference elimination technology, the characteristic of stability of an LEO satellite constellation global coverage signal and the high spectrum efficiency and flexibility of rate splitting multiple access.

Description

Technical Field

[0001] This invention relates to the field of radio technology, and in particular to a design method for satellite communication and navigation fusion multiple access signals based on continuous interference cancellation. Background Technology

[0002] With the explosive growth in the number of wireless communication terminal devices, spectrum resources are becoming increasingly scarce. Non-orthogonal multiple access (NOA) allows multiple users to share the same time-frequency resources for communication, significantly improving spectrum efficiency. Its core technology is continuous interference cancellation (CICC), which involves the receiver decoding the superimposed signals layer by layer in the power domain to eliminate interference from the outer layer signals to the inner layer signals, significantly improving the capacity and reliability of the wireless communication system. To cope with the fierce competition for scarce space resources and build an independent and controllable space information infrastructure, my country is vigorously promoting the construction of several large-scale low Earth Orbit (LEO) satellite constellations, such as the GW constellation and the Qianfan constellation. Previously, satellite navigation systems and satellite communication systems were independent in terms of frequency bands, constellations, and signal systems. However, with the development of signal processing technology and the signal processing capabilities of satellite communication payloads, as well as the dense deployment of LEO satellite constellations, deep integration of communication and navigation via LEO satellites has become possible. Communication-navigation fusion technology aims to achieve infrastructure reuse and spectrum sharing through unified design at the signal level, and has become a key direction for improving the efficiency of spatiotemporal information service systems. To address this need, this invention proposes a satellite communication and navigation fusion multiple access signal design method based on continuous interference cancellation. This method achieves deep integration of the two, thereby effectively improving the utilization efficiency of scarce frequency and track resources. Summary of the Invention

[0003] In order to solve the problems in the prior art, this invention proposes a design method for satellite communication and navigation fusion multiple access signals based on continuous interference cancellation.

[0004] This invention is achieved through the following technical solution: This invention proposes a design method for satellite communication and navigation fusion multiple access signals based on continuous interference cancellation, the method specifically being:

[0005] Step 1: Construct a satellite communication and navigation fusion multiple access system model for a multi-satellite, multi-user scenario; the satellite communication and navigation fusion multiple access system model for a multi-satellite, multi-user scenario includes 4 LEO satellites and multiple ground terminals;

[0006] Step Two: Based on the communication capacity required by different users within the system and the channel conditions between users and the satellite group, users are divided into 4 groups, U 总 =U1∪U2∪U3∪U4={1,2,...,K 总}, Each satellite is assigned to one group of users. Communication services are provided using rate split multiple access.

[0007] Step 3: Consider the system's operating frequency band as consisting of 4 bands with a bandwidth of B. i Composed of sub-bands, with a total bandwidth of B 总 ,satisfy Satellite i (1≤i≤4) uses one of the bandwidths B i The sub-band uses OFDM to transmit user group communication data, with a bandwidth of B. i The sub-band is divided into L i Subcarriers, C i Indicates bandwidth as B i The sub-band corresponding to L i The set of subcarriers is represented as

[0008] C 总 =C1∪C2∪C3∪C4={1,2,...,L 总}, L represents the set of all subcarriers in the system. 总 For bandwidth B 总 The total number of subcarriers corresponding to the total frequency band, and each satellite transmits positioning signals using OFDM on the total frequency band of the system;

[0009] Step 4: The ZC sequence is a complex sequence of points on the unit circle in the complex plane, possessing a constant envelope. The specific calculation formula is as follows:

[0010]

[0011] Where μ i The root index is L, and the sequence length is L. To ensure system compatibility between communication and positioning signals, the code length is kept consistent with the number of OFDM subcarriers in the system. The four satellites in the system use the same ZC sequence length but correspond to different μ values. i The cross-correlation characteristics of ZC sequences with different root sequence numbers, which have no significant correlation peaks, are used to distinguish the satellites from which the signals originate.

[0012] Step 5: Satellite i will transmit the ZC sequence c i,定位 (k) modulated into a time-domain OFDM symbol data stream s i,定位 And for the ZC sequence data stream s i,定位 Perform precoding;

[0013] Step Six: Each satellite divides the user communication data that it needs to provide communication data transmission services into two parts: a public part and a private part, according to the rate-based segmented multiple access strategy.

[0014] Step 7: Each satellite precodes the data stream vector;

[0015] Step 8: Satellite i will superimpose the positioning and communication signals it transmits in the power domain;

[0016] Step Nine: After transmission through the channel, user u i,k Received signals y from all four satellites in the system i→k Represented as

[0017]

[0018] Where y j,i→k,通信 =h j,i→k x j,通信 Indicates user u i,k The received communication signal sent by satellite j, y j,i→k,定位 =h j,i→k x j,定位 Indicates user u i,k The received positioning signal sent by satellite j, h j,i→k User u i,k With satellite j's N j Channel gain between beams n k The mean is 0 and the variance is Additive white Gaussian noise is used, and users achieve propagation delay measurement and time synchronization by matching the received signal with a local reference ZC sequence;

[0019] Step 10: After a certain propagation time, the OFDM signal exhibits a phase difference between different subcarriers that is linearly related to the propagation delay. The signal propagation delay can be obtained by calculating the linear phase slope of the subcarriers. After successfully measuring the propagation delay of the positioning signal, since the information contained in the positioning signal is known, the user removes the positioning signal from the received signal using continuous interference cancellation technology, thus eliminating the interference of the positioning signal on the communication signal.

[0020] Step 11: Since each satellite transmits communication signals using a different sub-band within the total frequency band, user u i,k The communication signal transmitted by satellite i can be effectively extracted from the remaining signal after removing the positioning signal through bandpass filtering. (User u) i,k The received communication signal from satellite i is

[0021]

[0022] Step 12: User u i,k First, treat all private data as interference, and then target the public data stream s. i,0 Decode;

[0023] Step 13: After successfully decoding the public stream and removing the public stream signal from the remaining signal through continuous interference cancellation, user u i,k Decode the private stream s composed of the user's private data i,k SINR at that time:

[0024]

[0025] User u i,k The achievable rates of the public and private streams of decoding satellite i are R, respectively. i,i→k,0 =log2(1+γ) i,i→k,0 ) and R i,i→k =log2(1+γ) i,i→k The actual rate of public flow transmission R of satellite i i,0 Cannot exceed U i The achievable public flow rate for any user Where C i,导航 It is R i,0 The rate at which navigation message data is transmitted from satellite i in the middle, C i,i→k It is R i,0 China Transmission User u i,k The corresponding public message rate, user u i,k The rate at which the corresponding communication data is decoded is R. i,i→k,通信 =C i,i→k +R i,i→k .

[0026] Furthermore, in step five, the positioning signal transmitted by satellite i is represented as follows:

[0027] x i,定位 =p i,定位 s i,定位

[0028] in This is the precoding vector corresponding to the ZC sequence.

[0029] Furthermore, in step six, satellite i passes through bandwidth B i User group U transmitted in the corresponding frequency band i The communication data and navigation messages of the satellite, user u i,k Communication data M i,k It will be divided into a public part M i,k,公有 and private part M i,k,私有 Navigation message M of satellite i i,导航 Will and U i Public data M of all users i,k,公有 (1≤k≤K i Encode together into a public stream s i,0 In the middle, the user's private data M i,k,私有(1≤k≤K i These are then encoded separately as private streams. Satellite i represents the communication data stream it transmits as follows:

[0030] Furthermore, in step seven, satellite i uses a precoding matrix For data stream vector s i,通信 Linear precoding is performed on the communication signal x transmitted by satellite i. i,通信 Represented as

[0031]

[0032] Optimize the linear precoding matrix P i To maximize the system's communication capacity.

[0033] Furthermore, in step eight, the superimposed signal is represented as

[0034]

[0035] Furthermore, in step ten, the specific method of continuous interference cancellation technology is that the terminal combines the channel response, the measured delay and the local ZC sequence to perform high-precision simulation of the positioning signal in the received signal, and then inputs the simulated positioning signal and the received signal into an adder to remove the positioning signal from the received signal.

[0036] Furthermore, in step twelf, in user u i,k Decodes i,0 The SINR is:

[0037]

[0038] Other user groups U w User u in w,k It also needs to receive positioning signals and navigation messages from satellite i, and user u w,k Received communication signal y from satellite i i,w→k Represented as:

[0039]

[0040] User u w,k Decoding the public stream s from satellite i i,0 The SINR at that time was:

[0041]

[0042] User u w,k The achievable rate of decoding the public stream from satellite i is R. i,w→k,0 =log2(1+γ) i,w→k,0Since the navigation message is included in the public stream, user u w,k Only the navigation message from the data transmitted by satellite i is needed, R i,w→k,0 It must not be lower than the minimum rate required for satellite transmission of navigation messages.

[0043] The beneficial effects of this invention are:

[0044] (1) The coverage capability of the LEO satellite mega-constellation and the advantages of low signal attenuation and low latency were leveraged to establish a satellite communication and navigation fusion multiple access system model.

[0045] (2) Based on the concept of spectrum sharing, continuous interference cancellation technology is used to avoid interference between positioning signals and communication signals, so that a group of satellites can provide communication and navigation positioning services to users at the same time, which significantly improves the utilization rate of frequency and orbit resources.

[0046] (3) By utilizing the good autocorrelation and cross-correlation characteristics of the ZC sequence, it is possible to achieve high-precision measurement of propagation delay and pseudorange and accurate differentiation of different satellite positioning signals.

[0047] (4) Users are flexibly grouped according to their channel quality and communication capacity requirements. Users in the same group adopt a rate split multiple access strategy to realize the reuse of time and frequency resources for multiple users, which improves terminal access density and spectrum efficiency. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the LEO satellite communication and navigation fusion system architecture.

[0050] Figure 2 This is a schematic diagram of the transmitter rate splitting model.

[0051] Figure 3 This is a schematic diagram of the signal processing model at the receiving end.

[0052] Figure 4 This is a schematic diagram illustrating the accuracy of propagation delay calculation under different power allocation ratios (5 beams, 5 users).

[0053] Figure 5 This is a schematic diagram of communication capacity under different power allocation ratios (5 beams, 5 users).

[0054] Figure 6This is a schematic diagram of the measurement results of the received positioning signal delay (power allocation ratio 14dB, 5 beams, 5 users).

[0055] Figure 7 This is a schematic diagram of the system's communication throughput performance. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] The purpose of this invention is to propose a design method for satellite communication and navigation fusion multiple access signals based on continuous interference cancellation (CICC). With the increasing maturity of CICC technology, and considering the anti-interference capability of satellite navigation signals and the deterministic nature of the pseudo-random sequences used by navigation satellites, the technical complexity of simulating and removing positioning signals from received signals using CICC is lower than the layer-by-layer decoding in non-orthogonal multiple access (NOA) systems. This makes it possible to apply CICC technology to communication and navigation fusion waveform design. Furthermore, to leverage the advantages of CICC technology in multiple access, this invention combines a rate-split multiple access strategy to provide downlink communication services to multiple users using the same time-frequency resources. Considering the compatibility of positioning information sequences with CICC technology, the stable signal characteristics of LEO satellite constellations covering the entire region, and the high spectral efficiency and flexibility of rate-split multiple access, a communication and navigation fusion multiple access scheme is designed.

[0058] Specifically, see Figures 1-7 This invention proposes a satellite navigation fusion multiple access system based on continuous interference cancellation, such as... Figure 1As shown, thanks to the fact that giant LEO satellite constellations often consist of tens of thousands of satellites, such a large-scale constellation can not only achieve global coverage, but also ensure that a ground terminal is simultaneously within the signal coverage range of multiple satellites. This allows the ground terminal to simultaneously receive positioning signals from multiple LEO satellites for accurate positioning, and multiple satellites can group and provide communication services to a massive number of ground terminals. Communication and navigation signals share the same spectrum resources by superimposing power domain signals at the transmitting end, while the receiving end uses continuous interference cancellation technology to eliminate interference from positioning signals to communication signals. After a certain propagation time, OFDM signals exhibit a phase difference between different subcarriers that is linearly related to the propagation delay. By calculating the linear phase slope of the subcarriers, the signal propagation delay can be obtained. Combined with the prominent autocorrelation peaks of the ZC sequence, the receiving end can achieve high-precision propagation delay and pseudorange measurement with time synchronization. The cross-correlation characteristics of ZC sequences with different root sequence numbers, where there are no significant correlation peaks, can be used to distinguish the source satellite of the signal.

[0059] The method of this invention is implemented through the following steps:

[0060] Step 1: Construct a satellite communication and navigation fusion multiple access system model for a multi-satellite, multi-user scenario; the satellite communication and navigation fusion multiple access system model for a multi-satellite, multi-user scenario includes 4 LEO satellites and multiple ground terminals.

[0061] Step Two: Based on the communication capacity required by different users within the system and the channel conditions between users and the satellite group, users are divided into 4 groups, U 总 =U1∪U2∪U3∪U4={1,2,...,K 总}, Each satellite is assigned to one group of users. Communication services are provided using rate split multiple access.

[0062] Step 3: The system's operating frequency band can be considered as consisting of 4 bands with a bandwidth of B. i Composed of sub-bands, with a total bandwidth of B 总 ,satisfy Satellite i (1≤i≤4) uses one of the bandwidths B i The sub-band uses OFDM to transmit user group communication data, with a bandwidth of B. i The sub-bands can be divided into L i Subcarriers, C i Indicates bandwidth as B i The sub-band corresponding to L i The set of subcarriers is represented as C 总 =C1∪C2∪C3∪C4={1,2,...,L 总}, L represents the set of all subcarriers in the system. 总 For bandwidth B 总 The total number of subcarriers corresponding to the total frequency band, and each satellite transmits positioning signals using OFDM on the total frequency band of the system.

[0063] Step 4: The ZC sequence is a complex sequence of points on the unit circle in the complex plane, possessing a constant envelope. The specific calculation formula is as follows:

[0064]

[0065] There are two key parameters: the root index μ i In order to achieve system compatibility between communication and positioning signals, the code length is consistent with the number of OFDM subcarriers in the system, along with the sequence length L. The four satellites in the system use the same ZC sequence length but correspond to different μ values. i When the sequence is correlated with any non-zero cyclic shift of itself, the result is almost zero; sharp peaks are only produced when perfectly aligned; the cross-correlation values ​​between ZC sequences with different root indices are bounded and remain at a low level. After a certain propagation time, there is a phase difference between different subcarriers that is linearly related to the propagation delay. The signal propagation delay can be obtained by calculating the linear phase slope of the subcarriers. Combined with the prominent autocorrelation peaks of the ZC sequence, the terminal can achieve high-precision propagation delay and pseudorange measurement and time synchronization by performing matched filtering on the received signal and the locally generated reference ZC sequence. The cross-correlation characteristics of ZC sequences with different root sequence numbers, which have no significant correlation peaks, can be used to distinguish the source satellite of the signal.

[0066] Step 5: Satellite i will transmit the ZC sequence c i,定位 (k) modulated into a time-domain OFDM symbol data stream s i,定位 And for the ZC sequence data stream s i,定位 After precoding, the positioning signal transmitted by satellite i can be represented as

[0067] x i,定位 =p i,定位 s i,定位

[0068] in This is the precoding vector corresponding to the ZC sequence.

[0069] Step Six: Each satellite, according to the rate-division multiple access strategy, divides the user communication data it needs to provide communication data transmission services into two parts: a public part and a private part. For example, satellite i will use bandwidth B... i User group U transmitted in the corresponding frequency band i The communication data and navigation messages of the satellite, user u i,kCommunication data M i,k It will be divided into a public part M i,k,公有 and private part M i,k,私有 Navigation message M of satellite i i,导航 Will and U i Public data M of all users i,k,公有 (1≤k≤K i Encode together into a public stream s i,0 In the middle, the user's private data M i,k,私有 (1≤k≤K i These are then encoded separately as private streams. The communication data stream transmitted by satellite i can be represented as

[0070] Step 7: Each satellite precodes the data stream vector. For example, satellite i uses a precoding matrix... For data stream vector s i,通信 Linear precoding is performed on the communication signal x transmitted by satellite i. i,通信 It can be represented as

[0071]

[0072] Optimize the linear precoding matrix P i It can maximize the system's communication capacity.

[0073] Step 8: Satellite i superimposes the positioning and communication signals it transmits in the power domain. The superimposed signal can be represented as follows:

[0074]

[0075] Step Nine: After transmission through the channel, user u i,k Received signals y from all four satellites in the system i→k It can be represented as

[0076]

[0077] Where y j,i→k,通信 =h j,i→k x j,通信 Indicates user u i,k The received communication signal sent by satellite j, y j,i→k,定位 =h j,i→k x j,定位 Indicates user u i,k The received positioning signal sent by satellite j, h j,i→k User u i,k With satellite j's N j Channel gain between beams n kThe mean is 0 and the variance is Additive white Gaussian noise (AWGN) allows users to measure propagation delay and synchronize time by matching the received signal with a local reference ZC sequence.

[0078] Step 10: After a certain propagation time, the OFDM signal exhibits a phase difference between different subcarriers that is linearly related to the propagation delay. The signal propagation delay can be obtained by calculating the linear phase slope of the subcarriers. After successfully measuring the propagation delay of the positioning signal, since the information contained in the positioning signal is known, the user removes the positioning signal from the received signal using continuous interference cancellation technology, thus eliminating the interference of the positioning signal on the communication signal. The specific method of continuous interference cancellation technology is that the terminal combines the channel response, the measured delay, and the local ZC sequence to perform a high-precision simulation of the positioning signal in the received signal. Then, the simulated positioning signal and the received signal are input into an adder to remove the positioning signal from the received signal.

[0079] Step 11: Since each satellite transmits communication signals using a different sub-band within the total frequency band, user u i,k The communication signal transmitted by satellite i can be effectively extracted from the remaining signal after removing the positioning signal through bandpass filtering. (User u) i,k The received communication signal from satellite i is

[0080]

[0081] Step 12: User u i,k First, treat all private data as interference, and then target the public data stream s. i,0 Decode the code. (In user u) i,k Decodes i,0 The SINR is:

[0082]

[0083] Other user groups U w User u in w,k It also needs to receive positioning signals and navigation messages from satellite i, and user u w,k Received communication signal y from satellite i i,w→k It can be represented as:

[0084]

[0085] User u w,k Decoding the public stream s from satellite i i,0 The SINR at that time was:

[0086]

[0087] User u w,kThe achievable rate of decoding the public stream from satellite i is R. i,w→k,0 =log2(1+γ) i,w→k,0 Since the navigation message is included in the public stream, user u w,k Only the navigation message from the data transmitted by satellite i is needed, R i,w→k,0 It must not be lower than the minimum rate required for satellite transmission of navigation messages.

[0088] Step 13: After successfully decoding the public stream and removing the public stream signal from the remaining signal through continuous interference cancellation, user u i,k Decode the private stream s composed of the user's private data i,k SINR at that time:

[0089]

[0090] User u i,k The achievable rates of the public and private streams of decoding satellite i are R, respectively. i,i→k,0 =log2(1+γ) i,i→k,0 ) and R i,i→k =log2(1+γ) i,i→k The actual rate of public flow transmission R of satellite i i,0 Cannot exceed U i The achievable public flow rate for any user Where C i,导航 It is R i,0 The rate at which navigation message data is transmitted from satellite i in the middle, C i,i→k It is R i,0 China Transmission User u i,k The corresponding public message rate, user u i,k The rate at which the corresponding communication data is decoded is R. i,i→k,通信 =C i,i→k +R i,i→k .

[0091] Example

[0092] This invention proposes a satellite navigation fusion multiple access system based on continuous interference cancellation, such as... Figure 1 As shown, assuming 4 satellites provide communication and navigation positioning services to 20 users, each satellite activates N... i One beam, satellite orbital altitude set at 600km. Satellite transceiver antenna gain is 28dB, beam transmit power is 10W, communication signals and positioning signals are configured according to... Power is allocated proportionally, with the transmit power of the two parts distributed to each satellite beam according to the corresponding precoding matrix. The system carrier center frequency is 2.5 GHz, and the total system bandwidth is 20 MHz. Satellite 1 transmits communication signals in the 2.490 GHz-2.495 GHz band, Satellite 2 in the 2.495 GHz-2.500 GHz band, Satellite 3 in the 2.500 GHz-2.505 GHz band, and Satellite 4 in the 2.505 GHz-2.510 GHz band. The satellites use OFDM to transmit positioning and communication signals, with a subcarrier spacing of 15 kHz. Each subband is allocated 256 subcarriers, and all 1024 subcarriers are used to transmit ZC sequence positioning signals in the complete system operating frequency band of 2.490 GHz-2.510 GHz. The ZC sequence length is 1024, and the root indices of the four satellites are 2, 3, 5, and 7, respectively. The terminal transceiver antenna gain is 0 dB.

[0093] The method of this invention is implemented through the following steps:

[0094] Step 1: Construct a satellite communication and navigation fusion multiple access system model for a multi-satellite, multi-user scenario; the satellite communication and navigation fusion multiple access system model for a multi-satellite, multi-user scenario includes 4 LEO satellites and multiple ground terminals.

[0095] Step Two: Based on the communication capacity required by different users within the system and the channel conditions between users and the satellite group, users are divided into 4 groups, U 总 =U1∪U2∪U3∪U4={1,2,...,K 总}, Each satellite is assigned to one group of users. Communication services are provided using rate split multiple access.

[0096] Step 3: The system's operating frequency band can be considered as consisting of 4 bands with a bandwidth of B. i Composed of sub-bands, with a total bandwidth of B 总 ,satisfy Satellite i (1≤i≤4) uses one of the bandwidths B i The sub-band uses OFDM to transmit user group communication data, with a bandwidth of B. i The sub-bands can be divided into L i Subcarriers, C i Indicates bandwidth as B i The sub-band corresponding to L i The set of subcarriers is represented as C 总 =C1∪C2∪C3∪C4={1,2,...,L 总}, L represents the set of all subcarriers in the system. 总 For bandwidth B 总 The total number of subcarriers corresponding to the total frequency band, and each satellite transmits positioning signals using OFDM on the total frequency band of the system.

[0097] Step 4: The ZC sequence is a complex sequence of points on the unit circle in the complex plane, possessing a constant envelope. The specific calculation formula is as follows:

[0098]

[0099] There are two key parameters: the root index μ i In order to achieve system compatibility between communication and positioning signals, the code length is consistent with the number of OFDM subcarriers in the system, along with the sequence length L. The four satellites in the system use the same ZC sequence length but correspond to different μ values. i When the sequence is correlated with any non-zero cyclic shift of itself, the result is almost zero; sharp peaks are only produced when perfectly aligned; the cross-correlation values ​​between ZC sequences with different root indices are bounded and remain at a low level, enabling the terminal to achieve high-precision propagation delay and pseudorange measurement and time synchronization by performing matched filtering on the received signal and the locally generated reference ZC sequence; and the cross-correlation characteristics of ZC sequences with different root sequence numbers without significant correlation peaks are used to distinguish the source satellite of the signal.

[0100] Step 5: Satellite i will transmit the ZC sequence c i,定位 (k) modulated into a time-domain OFDM symbol data stream s i,定位 And for the ZC sequence data stream s i,定位 After precoding, the positioning signal transmitted by satellite i can be represented as

[0101] x i,定位 =p i,定位 s i,定位

[0102] in This is the precoding vector corresponding to the ZC sequence.

[0103] Step Six: Each satellite, according to the rate-division multiple access strategy, divides the user communication data it needs to provide communication data transmission services into two parts: a public part and a private part. For example, satellite i will use bandwidth B... i User group U transmitted in the corresponding frequency band i The communication data and navigation messages of the satellite, user u i,k Communication data M i,k It will be divided into a public part M i,k,公有 and private part M i,k,私有 Navigation message M of satellite i i,导航 Will and Ui Public data M of all users i,k,公有 (1≤k≤K i Encode together into a public stream s i,0 In the middle, the user's private data M i,k,私有 (1≤k≤K i These are then encoded separately as private streams. The communication data stream transmitted by satellite i can be represented as

[0104] Step 7: Each satellite precodes the data stream vector. For example, satellite i uses a precoding matrix... For data stream vector s i,通信 Linear precoding is performed on the communication signal x transmitted by satellite i. i,通信 It can be represented as

[0105]

[0106] Optimize the linear precoding matrix P i It can maximize the system's communication capacity.

[0107] Step 8: Satellite i superimposes the positioning and communication signals it transmits in the power domain. The superimposed signal can be represented as follows:

[0108]

[0109] Step Nine: After transmission through the channel, user u i,k Received signals y from all four satellites in the system i→k It can be represented as

[0110]

[0111] Where y j,i→k,通信 =h j,i→k x j,通信 Indicates user u i,k The received communication signal sent by satellite j, y j,i→k,定位 =h j,i→k x j,定位 Indicates user u i,k The received positioning signal sent by satellite j, h j,l,i→k User u i,k With satellite j's N j Channel gain between beams n k The mean is 0 and the variance is Additive white Gaussian noise (AWGN) allows users to measure propagation delay and synchronize time by matching the received signal with a local reference ZC sequence.

[0112] Step 10: After a certain propagation time, the OFDM signal exhibits a phase difference between different subcarriers that is linearly related to the propagation delay. The signal propagation delay can be obtained by calculating the linear phase slope of the subcarriers. After successfully measuring the propagation delay of the positioning signal, since the information contained in the positioning signal is known, the user removes the positioning signal from the received signal using continuous interference cancellation technology, thus eliminating the interference of the positioning signal on the communication signal. The specific method of continuous interference cancellation technology is that the terminal combines the channel response, the measured delay, and the local ZC sequence to perform a high-precision simulation of the positioning signal in the received signal. Then, the simulated positioning signal and the received signal are input into an adder to remove the positioning signal from the received signal.

[0113] Step 11: Since each satellite transmits communication signals using a different sub-band within the total frequency band, user u i,k The communication signal transmitted by satellite i can be effectively extracted from the remaining signal after removing the positioning signal through bandpass filtering. (User u) i,k The received communication signal from satellite i is

[0114]

[0115] Step 12: User u i,k First, treat all private data as interference, and then target the public data stream s. i,0 Decode the code. (In user u) i,k Decodes i,0 The SINR is:

[0116]

[0117] Other user groups U w User u in w,k It also needs to receive positioning signals and navigation messages from satellite i, and user u w,k Received communication signal y from satellite i i,w→k It can be represented as:

[0118]

[0119] User u w,k Decoding the public stream s from satellite i i,0 The SINR at that time was:

[0120]

[0121] User u w,k The achievable rate of decoding the public stream from satellite i is R. i,w→k,0 =log2(1+γ) i,w→k,0 Since the navigation message is included in the public stream, user u w,kOnly the navigation message from the data transmitted by satellite i is needed, R i,w→k,0 It must not be lower than the minimum rate required for satellite transmission of navigation messages.

[0122] Step 13: After successfully decoding the public stream and removing the public stream signal from the remaining signal through continuous interference cancellation, user u i,k Decode the private stream s composed of the user's private data i,k SINR at that time:

[0123]

[0124] User u i,k The achievable rates of the public and private streams of decoding satellite i are R, respectively. i,i→k,0 =log2(1+γ) i,i→k,0 ) and R i,i→k =log2(1+γ) i,i→k The actual rate of public flow transmission R of satellite i i,0 Cannot exceed U i The achievable public flow rate for any user Where C i,导航 It is R i,0 The rate at which navigation message data is transmitted from satellite i in the middle, C i,i→k It is R i,0 China Transmission User u i,k The corresponding public message rate, user u i,k The rate at which the corresponding communication data is decoded is R. i,i→k,通信 =C i,i→k +R i,i→k .

[0125] Figure 4 The analysis of positioning signals in communication signals and positioning signals The receiver delay measurement accuracy under the power allocation ratio shows that the system can achieve 100% measurement accuracy when the power allocation ratio does not exceed 14dB, proving that the communication and navigation fusion system can achieve high-precision and reliable positioning.

[0126] Figure 5 Analysis of communication signals and positioning signals The system's achievable communication capacity (each satellite has 5 beams, providing communication services to 5 users) under the specified power allocation ratio shows that, thanks to the use of continuous interference cancellation technology, high-throughput communication can still be achieved by superimposing the positioning signal and communication signal in the power domain. Furthermore, due to the presence of environmental noise, the system's achievable communication capacity converges to its maximum value when the power allocation ratio is not less than 14dB. Based on the above experimental results, it can be concluded that 14dB is the optimal power allocation ratio.

[0127] Figure 6 This example demonstrates the propagation delay measurement results of a single received positioning signal when the power distribution ratio is 14dB. This example effectively illustrates that the system can accurately distinguish positioning signals from different satellites and perform high-precision measurements of propagation delay and pseudorange even at extremely low signal-to-noise ratios.

[0128] Figure 7 This paper analyzes the achievable communication capacity (each satellite providing communication services to 5 users) in a communication-navigation fusion system when the power allocation ratio is 14 dB, comparing the rate split multiple access (RMA) method with non-orthogonal multiple access (NOA) and space-division multiple access (SDMA) methods. It shows that the RMA method achieves a higher communication capacity than NOA and SDMA methods. As the number of satellite beams increases, the advantages of the RMA method over NOA and SDMA become more pronounced. This is because the fundamental advantage of the RMA method lies in its more flexible interference management capability, and increasing the number of satellite beams further enhances its interference management capabilities.

[0129] The above provides a detailed description of the satellite communication and navigation fusion multiple access signal design method based on continuous interference cancellation proposed in this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A design method for satellite communication and navigation fusion multiple access signals based on continuous interference cancellation, characterized in that, The method is specifically as follows: Step 1: Construct a satellite communication and navigation fusion multiple access system model for a multi-satellite, multi-user scenario; the satellite communication and navigation fusion multiple access system model for a multi-satellite, multi-user scenario includes 4 LEO satellites and multiple ground terminals; Step Two: Based on the communication capacity required by different users within the system and the channel conditions between users and the satellite group, users are divided into 4 groups, U 总 =U1∪U2∪U3∪U4={1,2,...,K 总 }, Each satellite is assigned to one group of users. Communication services are provided using rate split multiple access. Step 3: Consider the system's operating frequency band as consisting of 4 bands with a bandwidth of B. i Composed of sub-bands, with a total bandwidth of B 总 ,satisfy Satellite i (1≤i≤4) uses one of the bandwidths B i The sub-band uses OFDM to transmit user group communication data, with a bandwidth of B. i The sub-band is divided into L i Subcarriers, C i Indicates bandwidth as B i The sub-band corresponding to L i The set of subcarriers is represented as C 总 =C1∪C2∪C3∪C4={1,2,...,L 总 }, L represents the set of all subcarriers in the system. 总 For bandwidth B 总 The total number of subcarriers corresponding to the total frequency band, each satellite is in the L of the system's total frequency band. 总 Positioning signals are transmitted using OFDM on each subcarrier; Step 4: The ZC sequence is a complex sequence of points on the unit circle in the complex plane, possessing a constant envelope. The specific calculation formula is as follows: Where μ i The root index is L, and the sequence length is L. To ensure system compatibility between communication and positioning signals, the code length is kept consistent with the number of OFDM subcarriers in the system. The four satellites in the system use the same ZC sequence length but correspond to different μ values. i The cross-correlation characteristics of ZC sequences with different root sequence numbers, which have no significant correlation peaks, are used to distinguish the satellites from which the signals originate. Step 5: Satellite i will transmit the ZC sequence c i,定位 (k) modulated into a time-domain OFDM symbol data stream s i,定位 And for the ZC sequence data stream s i,定位 Perform precoding; Step Six: Each satellite divides the user communication data that it needs to provide communication data transmission services into two parts: a public part and a private part, according to the rate-based segmented multiple access strategy. Step 7: Each satellite precodes the data stream vector; Step 8: Satellite i will superimpose the positioning and communication signals it transmits in the power domain; Step Nine: After transmission through the channel, user u i,k Received signals y from all four satellites in the system i→k Represented as Where y j,i→k,通信 =h j,i→k x j,通信 Indicates user u i,k The received communication signal sent by satellite j, y j,i→k,定位 =h j,i→k x j,定位 Indicates user u i,k The received positioning signal sent by satellite j, h j,l,i→k User u i,k With satellite j's N j Channel gain between beams n k The mean is 0 and the variance is Additive white Gaussian noise is used, and users can achieve propagation delay measurement and time synchronization by matching the received signal with the local reference ZC sequence; Step 10: After a certain propagation time, the OFDM signal exhibits a phase difference between different subcarriers that is linearly related to the propagation delay. The signal propagation delay can be obtained by calculating the linear phase slope of the subcarriers. After successfully measuring the propagation delay of the positioning signal, since the information contained in the positioning signal is known, the user removes the positioning signal from the received signal using continuous interference cancellation technology, thus eliminating the interference of the positioning signal on the communication signal. Step 11: Since each satellite transmits communication signals using a different sub-band within the total frequency band, user u i,k The communication signal transmitted by satellite i can be effectively extracted from the remaining signal after removing the positioning signal through bandpass filtering. (User u) i,k The received communication signal from satellite i is Step 12: User u i,k First, treat all private data as interference, and then target the public data stream s. i,0 Decode; Step 13: After successfully decoding the public stream and removing the public stream signal from the remaining signal through continuous interference cancellation, user u i,k Decode the private stream s composed of the user's private data i,k SINR at that time: User u i,k The achievable rates of the public and private streams of decoding satellite i are R, respectively. i,i→k,0 =log2(1+γ) i,i→k,0 ) and R i,i→k =log2(1+γ) i,i→k The actual rate of public flow transmission R of satellite i i,0 Cannot exceed U i The achievable public flow rate for any user Where C i,导航 It is R i,0 The rate at which navigation message data is transmitted from satellite i in the middle, C i,i→k It is R i,0 China Transmission User u i,k The corresponding public message rate, user u i,k The rate at which the corresponding communication data is decoded is R. i,i→k,通信 =C i,i→k +R i,i→k .

2. The method according to claim 1, characterized in that, In step five, the positioning signal transmitted by satellite i is represented as follows: x i,定位 =p i,定位 s i,定位 in This is the precoding vector corresponding to the ZC sequence.

3. The method according to claim 2, characterized in that, In step six, satellite i passes through bandwidth B i User group U transmitted in the corresponding frequency band i The communication data and navigation messages of the satellite, user u i,k Communication data M i,k It will be divided into a public part M i,k,公有 and private part M i,k,私有 Navigation message M of satellite i i,导航 Will and U i Public data M of all users i,k,公有 (1≤k≤K i Encode together into a public stream s i,0 In the middle, the user's private data M i,k,私有 (1≤k≤K i Then each is encoded separately as a private stream s i,i→1 ,..., Satellite i represents the communication data stream it transmits as follows:

4. The method according to claim 3, characterized in that, In step seven, satellite i uses a precoding matrix For data stream vector s i,通信 Linear precoding is performed on the communication signal x transmitted by satellite i. i,通信 Represented as Optimize the linear precoding matrix P i To maximize the system's communication capacity.

5. The method according to claim 4, characterized in that, In step eight, the superimposed signal is represented as follows:

6. The method according to claim 5, characterized in that, In step ten, the specific method of continuous interference cancellation technology is that the terminal combines the channel response, the measured delay and the local ZC sequence to perform high-precision simulation of the positioning signal in the received signal, and then inputs the simulated positioning signal and the received signal into an adder to remove the positioning signal from the received signal.

7. The method according to claim 6, characterized in that, In step twelf, in user u i,k Decodes i,0 The SINR is: Other user groups U w User u in w,k It also needs to receive positioning signals and navigation messages from satellite i, and user u w,k Received communication signal y from satellite i i,w→k Represented as: User u w,k Decoding the public stream s from satellite i i,0 The SINR at that time was: User u w,k The achievable rate of decoding the public stream from satellite i is R. i,w→k,0 =log2(1+γ) i,w→k,0 Since the navigation message is included in the public stream, user u w,k Only the navigation message from the data transmitted by satellite i is needed, R i,w→k,0 It must not be lower than the minimum rate required for satellite transmission of navigation messages.

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