Capacity Analysis And Signal Detection Of Satellite MIMO Communication

With the development of wireless communication technology,satellite communication has made great progress,and it has provided the global coverage of Internet access services.However,with the increasing demand for the rate of transmission,satellite communication,as an important means of global data transmission,has been unable to meet people's expectation.Therefore,the construction of high data rate and high reliability satellite communication link has drawn great attention.Multi-input multi-output(MIMO)technology has been widely adopted in various terrestrial communication standards.In order to improve the capacity of satellite communication system and maintain its competitiveness with terrestrial systems,the introduction of MIMO technology to SATCOM has become a hot solution.In this thesis,the characteristics of satellite MIMO channel are studied,and the influence of the correlation of received signals on the MIMO channel is analyzed.In satellite communication,the light-of-sight(LOS)component of signal is extremely strong and there are few scatters in the channel,which makes the correlation between spatial subchannels very large,resulting in huge loss of spatial multiplexing gain.Based on the LOS MIMO theory,the channel capacity of satellite MIMO is analyed.Then,to analyze the robustness of SAT LOS MIMO link,we studied the influence of phase perturbation,antenna displacement and satellite perturbation on the capacity of SAT-MIMO.Finally,aiming at the problem of the orthogonality of LOS MIMO channel matrix tends to be destroyed,which leads to an increase in the condition number,we proposed a lattice reduction aided MIMO detection scheme,which improved the condition number of the channel matrix by preprocessing the channel matrix at the receiver.Meanwhile,in order to reduce the computational complexity of the lattice reduction algorithm,we take advantage of the characteristics of the slow fading SAT MIMOchannel and put forward the scheme of “pre-reduction” of the channel matrix with the old unimodular matrix,and then use the greedy-based reduction algorithm for further reduction,which significantly reduces the complexity of the detection algorithm.In this thesis,a variety of relevant simulations are conducted,and the results showed that the SAT LOS-MIMO link constructed by the light-of-sight path has certain stability.As long as antennas are properly placed,it is feasible to obtain LOS MIMO spatial multiplexing gain for satellite communication.The research in this thesis provides theoretical basis and technical support for the development of SAT MIMO communication,and has certain reference value for promoting the application of satellite MIMO systems.