Research Of AMC Technique In The MIMO-OFDM System

With the development of society, mobile communication system support video, image, data and conversation services simultaneously are required. In order to satisfy the demand of transmitting large data rapidly, it need improve the efficiency of system transmitting data in the future Beyond Third Generation mobile communication systems. Therefore, the future mobile communication key techniques that can improve the efficiency of system transmitting data are always hot research topics.Efficiency is one of important indexes to evaluate a communication system performance. But efficiency generally conflict with robustness which is another important evaluating index. Therefore, it should banlance the two indexes according to request and emphasize particularly on one of them some times. The Adaptive Modulation and Coding (AMC) technique studied in this thesis is a kind of technique that can improve efficiency when robustness satisfies the system request.The thesis introduces the principle of MIMO-OFDM communication system. Firstly, we present the signal model, channel capacity and types of MIMO. We emphasize the principle and detecting algorithm of V-BLAST and the principle of precoding which will be used in our research. Then, the thesis introduces OFDM principle include system model, the creation of OFDM signal, guard interval, cyclic prefix, windowing and PAPR of OFDM system. Based on the descriptions of MIMO and OFDM, we introduce the MIMO-OFDM system model and signal model.The thesis illuminates the principle and realization of AMC. After introducing the AMC principle, we analyze the coding and decoding of Turbo code and two modulate modes that is QPSK and 16QAM.Then discuss EESM mapping method which can calculate effictive SINR of OFDM subchannel, and two rules selected from AMC transmission pattern that is Block Error Rate attain requires and throughput maximum.The thesis researches the performance of AMC in the MIMO-OFDM system. By simulating, we acquire the performance curve about V-BLAST system has no AMC, V-BLAST system using AMC and V-BLAST system using AMC and precoding. Analyzing the curve, it can conclude that the system will achieve a significant gain on the throughput performance after using AMC and precoding.That is to say, AMC and precoding can improve system efficiency.