Polarization MIMO Transmission Techniques For High Altitude Platform Communication System

In addition to the ground mobile communication system and satellite systems,High Altitude Platform Stations (HAPS) is the third wireless communicationservice system. It has characteristics of large range of covering, low propagationdelay and broadband capacity, which make HAPS quite suitable to providecommunication services for mobile terminal. At present, the researches aboutHAPS are still at the starting stage with many problems to be solved. The articleis based on the background that HAPS has provided communication services forChina Railway High-Speed. In order to promote the development of high altitudeplatform communication technology in China, the feasibility and applicability ofMIMO technology in HAPS will be analyzed. The details are included in threeaspects:First of all, channel model of high altitude platform polarization MIMO isdesigned. This model focuses on the influence of depolarization, channelcorrelation, transmission channel state and so on. Besides, ray tracing method iscombined with empirical statistical modeling method, received signal sequenceand its cumulative probability distribution function have been gotten bysimulation. In the meantime, XPD, elevation and influence of channel capacity indifferent environments have also been analyzed.Secondly, signal detection algorithm with low complexity for HAPS isproposed in this article, a variety of techniques are used to reduce its computa tioncomplexity effectively. In these techniques, we focus on one new method that canreduce times of matrix inversion operation. According to this algorithm, only onetime of matrix inversion operation is needed to calculate all the MMSE filteringvector (amount to MT).This algorithm is very suitable to achieve in HAPShardware system, whose load and power are limited.In the end, transmission system of high altitude platform polarization MIMOis designed in this article. It includes transmission system based on SISO MMSEPIC iteration algorithm and transmission system based on STBC code. In theSTBC polarization MIMO transmission system, simulating results of system errorrate under channel conditions in different states and different elevation are alsoanalyzed.