Space-Time Block Coding And Signal Detection For The MIMO-OFDM Systems

Space-time block coding receives widespread attention due to its simple structure and easy toimplement. It can provide a better diversity gain. Orthogonal Frequency Division Multiplexingtechnology may well withstand multipath fading and frequency selective fading in actualenvironment. So we combine STBC with MIMO-OFDM system. The combined systemeffectively solves the problems of practical wireless mobile communication and therefore itbecomes a hot research topic.In the paper, we mainly study and analyze coding and decoding algorithm of STBC. And thenwe combine this encoding scheme with MIMO-OFDM system. The coding and decodingalgorithm of combining STBC with V-BLAST is discussed. On the basis of existing research, weimprove the detection algorithm.First of all, the problems of the wireless mobile communication and its existing solutions areelaborated. We give the research status of STBC and analyze the advantages of STBC which isapplied in wireless communication system.Second, the channel model and channel capacity of MIMO system is introduced. The basicframework of OFDM system is given. To build a platform for the application of STBC in thissystem, we study the MIMO-OFDM system.Then, we study the coding and decoding algorithm of STBC-OFDM system. The systemperformance is simulated and analysed under different conditions. Lots of researches indicate thatthe system performance is optimal if the detection algorithm is the maximum likelihood (ML)algorithm. But the calculated amount of ML detection algorithm is very large. Therefore, it isdifficult to achieve in the actual environment. To reduce the calculated amount of ML, theequivalent channel matrix of the system is decomposed. The theoretical analysis and simulation areshown that the system performance is almost the same with the traditional ML under the conditionof reduced calculated amount.Finally, the coding and decoding algorithm of layered space-time code are introduced andsimulated. Layered space-time block code (LSTBC) is researched and applied into MIMO-OFDMsystem. The theoretical analysis and simulated results are shown that LSTBC is a well compromiseof reliability and validity. We mainly analyse QR detection algorithm of LSTBC. The simplified QR decomposition operation process is given. Then the improved QR detection algorithm isprovided. The simulation results demonstrate that the system performance of LSTBC increaseusing improved QR detection algorithm under the condition of reduced computational complexity.