Research On Key Techniques Of Distributed MIMO System Formed By Formation Flying Satellites

Satellite Communication is now one of the main methods of communications.With the development of satellite communications, many countries have launched a lot of satellites into space, which resulted in increasingly expensive orbit and spectrum resources. To meet the growing demand and saving cost of launching and recovery, the development of micro-satellites has gradually comes into people’s vision.Formation flying small satellites have the capabilities that a large satellite has, and it is more robust, cheaper and has shorter update period. Existing methods of micro-satellites formation has high computational complexity, and its errors becomes large over time, which makes it not suitable for primary theoretical analysis. In order to facilitate the early theoretical analysis, the second chapter comes up a new design method of configuration based on the desired formation shape which can easily calculate the orbital elements.Formation of satellites is the basis of distributed satellite MIMO system. Distributed MIMO system can provide macro space diversity for the system to improve the capacity of the system. The third chapter analyzed the spatial correlation and the capacity of the centralized MIMO system, and the de-correlation effect of a polarization MIMO channel. It shows that under certain conditions, the polarization of the antenna can be used to achieve zero correlation. On this basis, this article established and analyzed a distributed satellite MIMO system model, in which the satellites are equipped with polarized antennas. It turns out that this system has better performance compared with SISO system and centralized MIMO systems.The combination of smart antenna and MIMO system can improve the capacity gain and the anti-jamming performance. Beam-forming technology can effectively control the antenna to point the desired direction. There are many algorithm of beam-forming, such as LMS and RLS algorithm. The fourth chapter have simulated the LMS and RLS algorithm, and then improved the LMS algorithm by coming up a simplified variable step-size LMS algorithm. It proves that this algorithm is effective especially on satellite.