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CN-122001440-A - Multi-low orbit satellite cooperative communication method based on spectrum sensing assistance

CN122001440ACN 122001440 ACN122001440 ACN 122001440ACN-122001440-A

Abstract

A multi-low orbit satellite cooperative communication method based on spectrum sensing assistance is characterized in that a satellite with a lower relative orbit height senses a satellite with a higher relative orbit height by using a spectrum sensing technology in a multi-low orbit satellite cooperative system, and performs satellite-ground communication based on spectrum sensing assistance, specifically, a signal cycle delay characteristic is embedded at a transmitting end by using a cycle delay diversity technology, and corresponding processing is performed at a receiving end. The invention effectively detects and utilizes the frequency spectrum holes in real time, thereby realizing the effective improvement of the quality and the transmission performance of the satellite-ground communication link.

Inventors

  • ZHU JIE
  • YING KAI
  • WANG CHAO
  • XU TIANHENG
  • DU MIN

Assignees

  • 上海交通大学

Dates

Publication Date
20260508
Application Date
20241108

Claims (9)

  1. 1. A multi-low orbit satellite cooperative communication method based on spectrum sensing assistance is characterized in that a satellite with a lower relative orbit height senses the satellite with the higher relative orbit height by using a spectrum sensing technology through arranging a multi-low orbit satellite cooperative system, and performs satellite-ground communication based on spectrum sensing assistance.
  2. 2. The method of spectrum sensing assistance based multi-low orbit satellite based collaborative communication according to claim 1, wherein the multi-low orbit satellite collaborative system comprises a plurality of different orbital altitudes, wherein each of the orbital altitudes comprises at least one satellite, wherein each of the different orbital altitudes is a near-earth orbit comprising a relatively high near-earth orbit and a relatively low near-earth orbit, and wherein the positional relationship between the relatively low orbit satellite and the relatively high orbit satellite comprises the relatively low orbit satellite being located within a coverage area of a satellite having a relatively high orbit altitude, and the relatively low orbit satellite being located within an overlapping portion of the coverage areas of the plurality of satellites having a relatively high orbit altitude.
  3. 3. The method for collaborative communication with multiple low orbit satellites based on spectrum sensing assistance according to claim 1 wherein the spectrum sensing technique is to detect spectrum usage of the remaining satellites with respect to satellites with low orbit heights and obtain a result of whether the detected frequency band is occupied, specifically, determining whether a signal characteristic value at a delay exceeds the given threshold value by a reliable threshold value and deciding, and according to two transmission states of a main user in actual transmission, namely a transmission signal (H 1 ) and a non-transmission signal (H 0 ), the signals received by the low orbit satellites-SU are: Wherein R (n) is a signal detected by the low-orbit satellite-SU, s (n) = [ s 1 (n),s 2 (n)] T ,h＝[h 1 ,h 2 ] is a channel parameter corresponding to each of the two signals, v (n) is additive white gaussian noise, R 1 is a situation that the low-orbit satellite-SU considers that the detected frequency band is being used, and R 0 is a situation that the low-orbit satellite-SU considers that the detected channel is idle, that is, the first high-orbit satellite-PU 1 or the second high-orbit satellite-PU 2 is not transmitting.
  4. 4. The spectrum sensing assistance-based multi-low orbit satellite cooperative communication method according to claim 1, wherein the low orbit satellite-SU deciding process of the transmission state of the main user is as follows Wherein the threshold value is Signal properties, i.e. autocorrelation function of signal detected by low-orbit satellite-SU Where L is the sampling length of the received signal, i.e., the sampling window length, (. Cndot.) * is the conjugate operation.
  5. 5. The spectrum sensing assistance-based multi-low orbit satellite cooperative communication method according to claim 4, wherein, in order to distinguish a plurality of users multiplexing the same time frequency resource, each user i is allocated with a time delay delta i different from other users and substituted into an autocorrelation function E, the amplitude of the peak value is used as a characteristic value F i of the user i, and in the binary decision process of spectrum sensing, the characteristic values F i of different users are compared with a threshold value, so as to obtain whether the user is in information transmission.
  6. 6. The method for collaborative communication between multiple low orbit satellites based on spectrum sensing assistance according to claim 1 wherein the spectrum sensing assistance means that when the sensing result of a low orbit satellite-SU is that the detected frequency band is being occupied, the satellite will discard its own transmissions and continue to sense the remaining satellites, otherwise the satellite will occupy the idle frequency band to complete its own transmissions.
  7. 7. The spectrum sensing assistance-based multi-low orbit satellite cooperative communication method according to claim 4, wherein when there are a plurality of users whose states need to be decided, the OR rule is uniformly followed, namely, when the low orbit satellite-SU senses that only one user is in a transmission state, the main user group is considered to exist, and the detected frequency band is occupied; the threshold lambda and the false alarm probability P f in the OR rule satisfy the following conditions:
  8. 8. The method for collaborative communication of multiple low orbit satellites based on spectrum sensing assistance according to claim 1 wherein the transmitting end uses two antennas to generate transmission signals respectively, wherein the first path of signal s 1 (n) directly generates orthogonal frequency division multiplexing signals after quadrature amplitude modulation and adds cyclic prefix to transmit, and the second path of signal s 2 (n) needs to perform cyclic displacement according to artificial cyclic delay before adding cyclic prefix, specifically: Wherein delta is cyclic delay, X is number of subcarriers, M is total length of X and cyclic prefix, W N is twiddle factor, i.e A l,k is the data on the first symbol, the kth carrier in the OFDM signal, a function
  9. 9. The spectrum sensing assistance-based multi-low orbit satellite cooperative communication method according to claim 1, wherein when the user is in the service range of the satellite, the user forms an included angle with the satellite line and the beam center line Wherein L n is the distance between the user n and the satellite, D n is the ground distance between the user n and the beam center, h is the length of the beam center, Is a 3dB angle; Under low-frequency signals, a channel model in a satellite-ground link adopts a Shadowed-Rician model containing the exponential decay characteristic of Rician distribution and the random variation of Log-Normal distribution, and the probability distribution function is as follows: Wherein 1 F 1 (A; B; C) is a confluence super geometric function, B 0 is the average power of scattering components, m is the fading parameters distributed by Nakagami-m, Ω is the average power of LOS components, and the relationship between the elevation angle θ (20 degree≤θ≤80°) formed between the user and the satellite connection line and the ground and B 0 , m and Ω is ：b 0 (θ)＝-4.7943×10 -8 θ 3 +5.5784×10 -6 θ 2 -2.1344×10 -4 θ+3.271×10 -2 ,m(θ)＝6.3739×10 -5 θ 3 +5.8533×10 -4 θ 2 -1.5973×10 -1 θ+3.5156,Ω(θ)＝1.4428×10 -5 θ 3 -2.3798×10 -3 θ 2 +1.2702×10 -1 θ-1.4864.

Description

Multi-low orbit satellite cooperative communication method based on spectrum sensing assistance Technical Field The invention relates to a technology in the field of wireless communication, in particular to a multi-low orbit satellite cooperative communication method based on spectrum sensing assistance. Background In the world-integrated future 6G architecture, the trend of sharing the same frequency between satellites and terrestrial mobile communications is becoming more and more evident. Most of the existing research works consider a system of spectrum sensing auxiliary single orbit height satellite or single sensing main user, but do not consider a system model design of spectrum sensing auxiliary multi-low orbit satellite collaborative work which is oriented to the construction requirement of a future giant constellation and can be used for distinguishing a plurality of confusing user signals. Disclosure of Invention Aiming at the problems that the spectrum sensing problem in the non-orthogonal coding transmission in the satellite downlink scene can not be realized, the complex dynamic sensing problem in the multi-satellite cooperative ground transmission can not be realized and the problem that the user confusion and the false alarm floating are easy to generate in the precisely distinguished non-orthogonal multiple access system in the prior art, the invention provides a multi-low orbit satellite cooperative communication method based on the spectrum sensing assistance, and the effective improvement of the satellite-ground communication link quality and the transmission performance is realized by effectively detecting and utilizing the spectrum holes in real time. The invention is realized by the following technical scheme: The invention relates to a multi-low orbit satellite cooperative communication method based on spectrum sensing assistance, which is characterized in that a satellite with a lower relative orbit height senses the satellite with the higher relative orbit height by applying a spectrum sensing technology in a multi-low orbit satellite cooperative system, and performs satellite-ground communication based on spectrum sensing assistance, specifically, a signal circulation delay characteristic is embedded at a transmitting end by adopting a circulation delay diversity technology, and corresponding processing is performed at a receiving end. The multi-low orbit satellite cooperative system comprises a plurality of different orbit altitudes, wherein each orbit altitude comprises at least one satellite, each orbit altitude is a near-earth orbit, namely a relatively higher near-earth orbit and a relatively lower near-earth orbit, the position relationship between the satellite with the relatively lower orbit altitude and the satellite with the relatively higher orbit altitude comprises that the satellite with the relatively lower orbit altitude is positioned in the coverage area of the satellite with the relatively higher orbit altitude, and the satellite with the relatively lower orbit altitude is positioned in the overlapping part of the coverage area of the satellites with the relatively higher orbit altitude. The spectrum sensing technology refers to detecting spectrum usage conditions of other satellites with relatively low orbit heights and obtaining a result of whether the detected frequency band is occupied or not, specifically, determining whether a signal characteristic value at a delay position exceeds a given threshold value through a reliable threshold value and judging, and according to the fact that a main user has two transmission states in actual transmission, namely a transmission signal (H 1) and a non-transmission signal (H 0). The signals received by the low-orbit satellite-SU are: Wherein r (n) is a signal detected by the low-orbit satellite-SU, s (n) = [ s 1(n),s2(n)]T,h＝[h1,h2 ] is a channel parameter corresponding to each of the two paths of signals, and v (n) is additive Gaussian white noise. R 1 is the case where the low-orbit satellite-SU considers that the detected frequency band is being used, and R 0 is the case where the low-orbit satellite-SU considers that the detection channel is idle, i.e., the first high-orbit satellite-PU 1 or the second high-orbit satellite-PU 2 is not transmitting, respectively. The low orbit satellite-SU judges the transmission state of the main user as followsWherein the threshold value isSignal properties, i.e. autocorrelation function of signal detected by low-orbit satellite-SUWhere L is the sampling length of the received signal, i.e., the sampling window length, (. Cndot.) * is the conjugate operation. Preferably, in order to distinguish multiple users multiplexing the same time-frequency resource, each user i is assigned a time delay delta i different from other users, and after the time delay delta i is substituted into the autocorrelation function E, the amplitude of the peak value is taken as the characteristic value F i of