Mimo-ofdm System Synchronization Technology Research

Utilizing multi-antenna and developing space resources to achieve multi-input multi-output, MIMO communication can significantly increase the channel capacity without bandwidth and transmission power increasing.OFDM technology can effectively resist the frequency-selective fading channels.MIMO-OFDM is the core technology of the next generation mobile communication which is combined with MIMO and OFDM technology can greatly increase the channel capacity and transfer rates, effectively against the multi-path fading and restrain interference and noise.However,MIMO-OFDM system is very sensitive to timing and frequency synchronization error.Timing error will lead to inter-symbol interference and the frequency offset introduce the inter-carrier interference , both cause the serious decline of system performance. Therefore, accurate timing synchronization and frequency offset for MIMO-OFDM system is very important.The development, characteristics and basic principles of MIMO-OFDM system are analyzed firstly in this paper. Then, synchronization algorithms for different MIMO-OFDM system are discussed in detail, based on the introduce synchronization error model of MIMO-OFDM system and detailed analysis about the influence of synchronization error on the system. Aiming at the centralized MIMO-OFDM system, use constant amplitude zero auto-correlation (ZACAC) sequence as the training sequence to improve the Van Zelst. A's synchronization algorithm and test the performance of the improved algorithm by computer simulation. In low SNR,the simulation results show that the improved algorithm has a better synchronization performance. Under the same conditions, both frequency offset estimation and timing synchronization performance are improved. For the distributed MIMO-OFDM system, aiming at the shortcomings of UPSP algorithm, the paper proposed a kind of improved algorithm. Timing metric function of improved algorithm has the sharp peak that can accurately define the location of timing synchronization. The simulation results prove that the improved algorithm has a better synchronization performance than UPSP algorithm.