Research On Distributed Cluster Collaborative Communication And Space-time Coding Technology

With the development of communication technology,the land mobile communication system related technologies have supported the mobile Internet and Internet of Things technologies,which have brought about profound changes in modern society.However,in recent years,with the rapid development of space missions and space activities,especially the emergence of inter-satellite links,people have increasingly demanded that communication networks have end-to-end interactions,processing,and flexible and efficient networking capabilities,starting internationally.The study of spatial information networks,with the in-depth research of distributed satellite constellations has been highly valued by the international mainstream research institutions,based on the cooperative relationship between distributed satellite constellation,can build a high link between satellites and satellites.Gain to solve the fast and flexible access requirements of medium-and low-orbit satellites,aircrafts and ground users,to balance the conflict between coverage intensity and coverage,and at the same time provide strong support for reliable transmission of multi-user information with large capacity.However,due to the generally short distance between distributed satellites,ranging from tens of meters to several kilometers,this may lead to strong channel correlation.Under such conditions,distributed satellite constellation and MIMO The combination of Multiple Input Multiple Output and coding techniques is a necessary condition for satellite link enhancement.This paper first models the satellite mobile communication channel links,considers different atmospheric and weather conditions,and builds a three-state model of satellite links based on the Markov process.It is divided into LOS states,medium shadow fading states and deep fading.State,and simulated by computer simulation,and then set up a channel model between distributed satellite constellations through simulation analysis.Gaussian channel model is adopted after various aspects of calculation and analysis.In addition,for the main problem of using MIMO technology in satellite communication systems,that is,due to the strong channel correlation due to minimal angle expansion,resulting in a smaller gain of MIMO compared to the traditional SISO(Single Input Singual Output)system,the present study assumes an expansion.The correlation of the angles with the Gaussian distribution was quantitatively analyzed,and the approximate relationship between the angle and the antenna array distance and angle expansion was given.Based on the above analysis results,the Kronecker model is used to simulate the relevant channel capacity,and the distributed antenna system and the area array system are analyzed.It can be concluded quantitatively that the capacity of the satellite mobile system can be significantly improved through the distributed antenna system.Finally,this paper presents a precoding technology based on distributed virtual MIMO system.Using distributed space-time distributed coding technology,the diversity gain of the system is significantly improved,thereby improving the satellite spatial channel transmission performance.This paper simulates the satellite system composed of 4 distributed satellites and 4 terrestrial terminal systems,and analyzes the BER performance of QPSK,PSK and QAM systems of three different modulation methods,which verifies the effectiveness of the technology.