Mimo-ofdm Channel Estimation And Signal Detection

The combination of multiple-input multiple-output (MIMO) and orthogonal frequency division multiplexing (OFDM) can not only enhance the capacity of wireless communication system, but also offer the potential of high spectral efficiency and lessen the effects of frequency-selective fading. Therefore, MIMO and OFDM will be the key technologies for the next generation wireless communication system.This paper firstly discusses the characteristics of mobile channel. Then it introduces OFDM system and MIMO system. At the end of this chapter, it summarizes the main research contents.The second part of this paper mainly studies on some signal detection algorithms in MIMO-OFDM system, including Maximum a Posteriori probability detection (MAP) /Maximum Likelihood Detection (MLD), linear detection and interference cancellation detection which are consist of ordered successive interference cancellation (OSIC) and MMSE- parallel interference cancellation (MMSE-PIC). The simulation results suggest that the MLD has apparent advantages over other detection algorithms with highest complexity, and the interference cancellation detection is much better than linear detection. Considering the tradeoff between system performance and complexity, this paper chooses MMSE-PIC, which can be connected to the decoder to improve the system performance through iterations.The third part of this paper mainly studies on channel estimation technologies in MIMO-OFDM system. First, it overviews channel estimation technologies, and focuses on pilot-symbol-aided channel estimations. Then it proposes a new channel estimation technology based on phase compensation, which will eliminate the effect of pilot-tone shift with lower computation complexity. In the end, the comparison and simulation results are given to show that the proposed channel estimation algorithm can provide better performance.Based on the research of signal detection and channel estimation, the fourth part of this paper mainly accomplishes the design of Turbo receiver in MIMO-OFDM system. The simulation results suggest that combination of channel estimation, MMSE-PIC and Turbo decoder will improve the system performance greatly through iterations.In the end of this paper, the conclusions are made. What we should research on in future is also proposed.