CN-122001417-A - Low orbit satellite communication navigation integrated waveform design method based on downlink rate splitting multiple access

CN122001417ACN 122001417 ACN122001417 ACN 122001417ACN-122001417-A

Abstract

The invention provides a low-orbit satellite communication navigation integrated waveform design method based on downlink rate splitting multiple access. According to the method, a communication and navigation integrated system model based on a low-orbit satellite constellation is established by combining a spectrum sharing technology aiming at a low-orbit satellite Internet scene, a group of satellites provide communication and navigation positioning services for users at the same time, and the utilization rate of frequency orbit resources is improved. The method uses the good autocorrelation and cross-correlation properties of the ZC sequence, and uses the ZC sequence as a positioning signal to carry out the same-frequency-band power domain superposition with a communication signal, so that the accurate positioning can be realized even under the condition of extremely low signal-to-noise ratio. The method of the invention has lower complexity while improving the frequency track efficiency and the access density of the system.

Inventors

LI ZHIQIANG
YANG JINSHUO
GAO MINGZE
HAN SHUAI
WEN YAN
LI JING

Assignees

哈尔滨工业大学

Dates

Publication Date: 20260508
Application Date: 20251229

Claims (7)

1. The integrated waveform design method for low-orbit satellite communication navigation based on downlink rate splitting multiple access is characterized by comprising the following steps of: The method comprises the steps of constructing a satellite communication navigation integrated system model combined with rate division multiple access, wherein the satellite communication navigation integrated system model combined with rate division multiple access comprises four low-orbit satellites and a plurality of ground terminals; Selecting proper code length and distributing different root serial numbers for four satellites, so as to calculate ZC sequences corresponding to the four satellites respectively as positioning signals, and enabling a ground user to distinguish the positioning signals from different satellites by performing cyclic correlation on the received positioning signals to realize accurate ranging and positioning; Step three, grouping users according to the channel quality difference and communication requirement of the users in the common coverage area of all satellites, U total ＝U 1 ∪U 2 ∪U 3 ∪U 4 ＝{1,2,...,K total , Each satellite is respectively directed to one group of users Providing communication services by adopting rate splitting multiple access; Dividing a frequency band with the bandwidth of B sys into L total subcarriers, wherein each satellite transmits ZC sequence direct sequence spread spectrum signals serving as synchronization and positioning signals to all users in the system on a total frequency band corresponding to all subcarriers, and satellite i (i is more than or equal to 1 and less than or equal to 4) transmits navigation messages and communication data of a U i user group through subcarrier set C i distributed to the satellite; step five, precoding vector for each satellite Precoding ZC sequence data stream s i,ZC , and the positioning signal sent by satellite i is expressed as x i,ZC ＝p i,ZC s i,ZC Step six, each satellite segments the user communication data in the corresponding group; step seven, each satellite carries out linear precoding on the data stream vector by using a precoding matrix; step eight, representing all signals transmitted by satellite i as Step nine, signals y i→k from all I satellites in the system received by the user u i,k after the channel transmission are expressed as follows: Where y j,i→k,com ＝h j,i→k x j,com represents the communication signal transmitted by satellite j received by user u i,k and y j,i→k,ZC ＝h j,i→k x j,ZC represents the positioning signal transmitted by satellite j received by user u i,k ; Step ten, the user carries out propagation delay measurement and time synchronization by carrying out cyclic correlation detection on the received signal and the local reference ZC sequence; step eleven, the user extracts the communication signal from the received signal through band-pass filtering; step twelve, user u i,k first demodulates public data stream s i,0 by using all private data as interference; thirteenth, after successfully decoding the public stream and removing the public stream signal from the received signal by successive interference cancellation, user u i,k decodes the SINR of private stream s i,k : The reachable rates of decoding the public and private streams by user U i,k are R i,i→k,0 ＝log 2 (1+γ i,i→k,0 ) and R i,i→k ＝log 2 (1+γ i,i→k ), respectively), the rate R i,0 of actual transmission of the public stream by satellite i cannot exceed the reachable public stream rate of any user in U i Wherein C i,nav is the rate of transmitting navigation message data of satellite i in R i,0 , C i,i→k is the rate of transmitting public message corresponding to user u i,k in R i,0 , and the rate of decoding the corresponding communication data by user u i,k is R i,i→k,com ＝C i,i→k +R i,i→k .
2. The method of claim 1, wherein the ZC sequence data stream is: Wherein mu i is the root sequence number allocated to the satellite, and L is the code length of the ZC sequence.
3. The method of claim 2, wherein the total set of subcarriers is denoted as C total ＝C 1 ∪C 2 ∪C 3 ∪C 4 ＝{1,2,...,L total , Note that C i includes L i subcarriers, denoted as The corresponding sub-band bandwidth is B i ,
4. A method according to claim 3, wherein in step six, on satellite i, the message sent to user group U i via subcarrier set C i is a combination of the communication data of all users U i,k (1≤k≤K i ) and the navigation messages of the satellite, the message W i,k of user U i,k is split into common parts And private part Navigation messages W i,nav for satellite i are encoded as part of the communication data in public stream s i,0 along with public messages W i,k,c (1≤k≤K i for all users in U i , private messages for users Then separately encoded as private streams Satellite i is represented by a transmitted communication data stream as
5. The method of claim 4, wherein in step seven, satellite i uses a precoding matrix Linear precoding of the data stream vector s i,com , the communication signal x i,com transmitted by satellite i is represented as The optimal system performance is obtained by optimizing the linear precoding matrix P.
6. The method of claim 5, wherein in step eleven, assuming that the positioning signal power is uniformly distributed within the system bandwidth, the remaining positioning signal power after bandpass filtering is expressed as The signal received by user u i,k on the sub-band corresponding to C i is represented as Where n k is the mean 0 and the variance is H i,l,i→k is the channel gain between user u i,k and the N i beams of satellite i,
7. The method of claim 6 wherein in step twelve, the SINR of the demodulated data stream s i,0 at user u i,k is The user U w,k in the other user group U w also needs to receive the positioning signal and the navigation message of the satellite i, and the communication signal y i,w→k received by the user U w,k from the satellite i is expressed as: User u w,k decodes SINR at common stream s i,0 from satellite i: User u w,k decodes the public stream from satellite i to an achievable rate of R i,w→k,0 ＝log 2 (1+γ i,w→k,0 ), since the navigation messages are contained in the public stream, user u w,k only needs the navigation messages in the data sent by satellite i, R i,w→k,0 cannot be lower than the minimum rate required by the satellite to transmit the navigation messages

Description

Low orbit satellite communication navigation integrated waveform design method based on downlink rate splitting multiple access Technical Field The invention relates to the technical field of radio, in particular to a low-orbit satellite communication navigation integrated waveform design method based on downlink rate splitting multiple access. Background To meet the "ubiquitous connection" communication requirement of global coverage and multidimensional fusion of 6G, the low-orbit satellite internet becomes an important component of 6G with the advantage of extremely low time delay of global coverage. In the face of the trend of the number index burst of the 6G terminals, the problem of frequency spectrum resource shortage is remarkable, the Rate division multiple access (Rate-split MultipleAccess, RSMA) is a novel non-orthogonal multiple access technology, the frequency spectrum utilization Rate can be remarkably improved, a satellite communication system and a satellite navigation system are completely separated in the past, different constellations and frequency spectrums are respectively used, the satellite frequency track resource shortage degree is increased gradually along with the construction acceleration of low-orbit satellite constellations of various countries, the communication navigation integration becomes the development trend of space-time information technology and the strategic focus of global competing, and the communication navigation spectrum sharing can be realized by integrally designing communication and navigation signals. In order to realize communication navigation integration, the invention provides a communication navigation integration waveform technology combining downlink rate split multiple access based on a low-orbit satellite constellation, realizes communication navigation integration on a signal coding strategy, and improves the utilization rate of frequency orbit resources. Disclosure of Invention The invention provides a low-orbit satellite communication navigation integrated waveform design method based on downlink rate split multiple access in order to solve the problems in the prior art. The invention is realized by the following technical scheme, and provides a low-orbit satellite communication navigation integrated waveform design method based on downlink rate splitting multiple access, which comprises the following steps: The method comprises the steps of constructing a satellite communication navigation integrated system model combined with rate division multiple access, wherein the satellite communication navigation integrated system model combined with rate division multiple access comprises four low-orbit satellites and a plurality of ground terminals; Selecting proper code length and distributing different root serial numbers for four satellites, so as to calculate ZC sequences corresponding to the four satellites respectively as positioning signals, and enabling a ground user to distinguish the positioning signals from different satellites by performing cyclic correlation on the received positioning signals to realize accurate ranging and positioning; Step three, grouping users according to the channel quality difference and communication requirement of the users in the common coverage area of all satellites, U total＝U1∪U2∪U3∪U4＝{1,2,...,Ktotal, Each satellite is respectively directed to one group of usersProviding communication services by adopting rate splitting multiple access; Dividing a frequency band with the bandwidth of B sys into L total subcarriers, wherein each satellite transmits ZC sequence direct sequence spread spectrum signals serving as synchronization and positioning signals to all users in the system on a total frequency band corresponding to all subcarriers, and satellite i (i is more than or equal to 1 and less than or equal to 4) transmits navigation messages and communication data of a U i user group through subcarrier set C i distributed to the satellite; step five, precoding vector for each satellite Precoding ZC sequence data stream s i,ZC, and the positioning signal sent by satellite i is expressed as xi,ZC＝pi,ZCsi,ZC Step six, each satellite segments the user communication data in the corresponding group; step seven, each satellite carries out linear precoding on the data stream vector by using a precoding matrix; step eight, representing all signals transmitted by satellite i as Step nine, signals y i→k from all 4 satellites in the system received by the user u i,k after the channel transmission are expressed as follows: Where y j,i→k,com＝hj,i→kxj,com represents the communication signal transmitted by satellite j received by user u i,k and y j,i→k,ZC＝hj,i→kxj,ZC represents the positioning signal transmitted by satellite j received by user u i,k; Step ten, the user carries out propagation delay measurement and time synchronization by carrying out cyclic correlation detection on the received signal and the local reference ZC se