The Research Of Signal Detection Based On MIMO-OFDM And ROF System

MIMO (Multiple-Input Multiple-Output) and (Orthogonal Frequency Division Multiplexing) are the key techniques of the 4G wireless communication system. MIMO uses antenna arrays between transmitter and receiver to establish MIMO sub-channels which can exponentially increase the capacity of the system. OFDM can improve the efficiency of the frequency by dividing the wireless channel into several orthogonal sub-carriers. These sub-carriers are overlapping with each other in frequency domain. So the combination of MIMO and OFDM is supposed to be a great trend in the future.Based on the MIMO-OFDM system, the paper did a lot of work on the theory analysis and mathematical derivation of the classic channel estimation and signal detection methods. Because linear MMSE detection method has a simpler array structure and less computational complexity, while Maximum Likelihood (ML) detection performs better than MMSE, but needs huge computational complexity. We proposed a novel Selective Signal Detection (SSD) algorithm based on Iterative calculation. Simulation results show that the new approach can improve the system BER performance at low SNR condition. When facing ideal BER environment, the method can reduce the signal processing time and guarantee the timeliness of the communication system. The proposed method is certified to have a lot practical value.At the end of this paper, the ROF (Radio Over Fiber) technique based on the MIMO-OFDM system that established before was introduced. A fractional sampling channel estimation method is used in simulation to solve the problem about chromatic dispersion and nonlinear distortion. Simulation results show that the method used is adequate for the hybrid system. The current achievements have laid a solid foundation for the research in the future.