Research On Coding In MIMO-OFDM System

The orthogonal frequency division multiplexing (OFDM) system is multicarrier systems and usually used to combat frequency selective fading or narrowband interfere. But in order to increase the systematic capacity further, raise the systematic transfer rate, only use OFDM technology broadband wireless communication means to need to increase the quantity of the sub signal carrier simply in a large amount, and this kind of method will increase systematic complexity by a wide margin, and take up the systematic bandwidth in a large amount, certainly will be very difficult to adapt to the limited bandwidth and power wireless LAN at present. But multiple input multiple output (MIMO) systems could improve the capacity of the communication system and spectral utilization ratio at double in case of not increasing bandwidth. Therefore, combing these techniques to form a MIMO OFDM system is a promising scheme for achieving high data rates for the future broadband wireless networks in frequency selected channel, example Bell-Labs Layered Space Time (BLAST) OFDM system. But, it is also important for MIMO-OFDM systems to adopt the good coding to decrease bad effect of MIMO-OFDM systems coming from path waste and improve accuracy of receive signals.This paper mainly studies the code technology of MIMO-OFDM system used in wireless communication, such as, space frequency coding, Turbo coding and BLAST coding. And put forward a more effective TuLST scheme. It takes iterative detection and decoding algorithm to realize circulation correct error and can resist and decrease fast fading in the high-speed mobile environment. At last we combine MIMO-OFDM system with space frequency block code and TuLST code to realize the most optimization combination of spce, time and frequency. The structure of this paper is as follows:Chapter one reviewed the development of the wireless LAN and basic principle of OFDM briefly. And then recommended every chapter arrange of this paper.Chaper two introduced the characteristic of the wireless mobile channel in mobile communication at first, and the fading effect caused. Secondly, analyse theprinciple block diagram of MIMO-OFDM system and set up MIMO-OFDM systematic model. Finally, we point out the improvement direction of MIMO system is modulating and error-correcting question, then draw the direction in which this paper studies.Chapter there mainly introduced space frequency code principle and decoded algorithms, and analysed the PER of space frequency block code and provided design standards about how to obstain the largest division gain through setting up SFBC-OFDM system. Thus we draw the reason why space frequency block code can be effect by multipath delay .Chapter four, brief analysis decode characteristic of Turbo code and BLAST coding technological characteristic, and have set up TuLST code method. And has carried on detailed analysis to the design of TuLST code and the coding and decoding algorithm. Verity TuLST code method through the artificial result finally.Chapter five, carry on SFBC-OFDMsysterm and TuLST code one grade of antithetical couplets, and verify systematic feasibility and validity through the analysis of performance and artificial result.