The Research Of The Anti-Noise Performance In The MIMO-OFDM System

Nowadays people demand for communication services is growing day by day. They want to get faster and more reliable service. The rapid development of wireless communication technology has changed our daily life greatly. Multiple-input multiple-output (MIMO) technology is a major breakthrough of smart antenna technique in the field of wireless mobile communications. The technology exponentially improves the communication system capacity and spectrum efficiency without increasing the bandwidth.It must be one of the key technologies of the next generation mobile communication system.However, as a Multi-carrier modulation technique, orthogonal frequency division multiplexing utilizes sub-carriers of parallel, low-rate data transmission to achieve a high-speed data transmission, which can overcome the signal fading caused by multipath propagation and the inter-symbol interference caused by symbol delay. It is the key technique in the fourth generation communication. The MIMO-OFDM technique, combined with MIMO technique and OFDM technique, can improve the system spectral efficiency and the channel capacity. Meanwhile it can reduce the complexity at the receiver. So, it will be the key solutions of wireless communication system in the future. In order to fully exert the superiority of the system it is necessary to research anti-noise performance and the signal processing at the receiver.In this paper, the research work, at home and abroad on the basis of MIMO-OFDM wireless communication system for the theory involved in a number of key technology and conducted in depth research, has been made on progress such as the anti-noise performance of MIMO-OFDM system,analyzed the internal rules of influence factors of anti-noise performance. Based on the analysis, this paper measured the overall resource efficiency of MIMO-OFDM system. The major work done by the following:1. The principle model of MIMO-OFDM system is analyzed.2. The MIMO-OFDM system BER formula is derived theoretically.3The MIMO-OFDM system is detected by using maximum likelihood method at the receiving end. In the case of an equal number of transmit and receive antennas, the bit error rate curve of this system will be simulated and made the comparison and analysis. Then in the case of the receiver antenna number is larger than the number of transmit antennas, simulation of the system bit error rate curve can be pictured by the computer. Also, we should make a comparison and analysis of this picture. At last the bit error rate curve of the system would be draw in different modulation ways. At the same time, we should summarize the general rules to improve the performance of the system based on this anti-noise curve.4. The last part of the paper the resource allocation efficiency of MIMO-OFDM system is evaluated based on the digital modulation way. At the same time the overall resource efficiency of the MIMO-OFDM system will be measured at the receiver of different test methods. The results show that, maximum likelihood detection (MLD) is the optimal detection algorithm, which overall efficiency of resources relatively high. In addition using M-ary quadrature amplitude modulation (MQAM) overall resource efficiency is higher than that of employing M-ary phase shift keying (MPSK).In the meantime, its overall resources efficiency is improving with the increase the value of M. This method can also be measured to describe other new kinds of digital modulation system of the BER performance of the system and the overall efficiency of resources.