Research On Space-time Coding In MIMO_OFDM System

With the development of telecommunication and improvement of people's living standard,new wireless communication system provides not only higher transmission rate,but also better quality.The most effect way to meet such requirements is the MIMO technology,which employs multiple antennas,improving the channel capacity multiply.On the other hand,OFDM technology,with the high ability of combating frequency selective fading and high frequency use ratio,if combining with MIMO,can improve the property of telecommunication system ,and achieve higher rate and better quality of data transmission in the wide-band system.This paper first introduces the basic theory of MIMO technology , deduces theoretically the channl capacity of MIMO system and obtains bit error rate of this system,then gets the space-time coding design criteria.Next this paper describes three main space-time coding techniques in detail,investigates the property of different space-time codes and makes comparsion between these codes.Based on above, this paper introduces system model of MIMO_OFDM,analyzes the system performance theoretically and shows the superiority by simulation.In the last,a new mix space-time coding is presented,which combines advantages of layered space-time code and space-time block code,making the system performance best.what's more,this method empolys the group interference suppression measure for decoding.Simulation results show the feasibility of this method.