The Research Of Channel Estimation In MIMO-OFDM Wireless Communication System

With the rapid development of wireless communication technology, the demand for communication services is not limited in voice area. Images, video, data, network services are also on the growth. This requires advanced capability for wireless communication system. High-speed, large capacity, high reliability, multi-service types will be the main features of the future wireless communication system. At the same time, the MIMO-OFDM wireless communication system greatly meets the needs of the next generation communication system. The channel estimation for MIMO-OFDM wireless communication system is a significant part which is directly related to communication quality.In this paper, we mainly introduced MIMO(Multiple Input and Multiple Output) and OFDM (Orthogonal Frequency Division Multiplexing) techniques. MIMO technique supplies high-capacity by multi-antennas, while OFDM technique generates multi-carrier signals by parallel transmission technology which is strictly orthogonal between each other. Through this, we weaken the needs for system's wide spectral bandwidth, which is undoubtedly a big improvement under the circumstance of the rare spectrum resources. In this way, we resisted the noise, interference, signal fading effect. The two techniques constitute MIMO-OFDM wireless communication system. Then we discussed the features of the wireless channel, analyzed the model of it, including multi-path delay, Doppler frequency shift and Rayleigh fading. Finally, we made the research on non-blind channel estimation in MIMO-OFDM wireless communication system based on pilot signal, introduced the form and structure of pilot signal, mainly discussed the least square error channel estimation algorithm, minimum mean-square error channel estimation algorithm, linear minimum mean-square error channel estimation algorithm, compared the performance of the three ways through Matlab computer simulation and analyzed the complexity of the algorithms and application performance. We improved the interpolation and filter way in the channel estimation process to remove the noise as much as possible and concentrate the energy of the useful signal through wavelet denoising and adding window function. And in this way we lower down the bit error rate of the system. The computer simulation results show the performance is better and better as the signal to noise ratio has improved. This way provides great help to the optimization of MIMO-OFDM wireless communication system.The study and simulation of channel estimation in MIMO-OFDM wireless communication system indicates it is a very promising area.