Research Of Channel Estimation And Signal Detection Technique In MIMO-OFDM Systems

MIMO-OFDM is an important developing direction of future broadband wireless communication system. This technique can improve the tolerance limit to noise, interference and mufti-path effect by introducing array antennas to OFDM communication system and utilizing space-time-frequency three dimensional signal processing technique. In this paper, the focus is channel estimation and signal detection. The MATLAB simulation has carried on the comprehensiveanalysis and the comparison to these methods validity and thefeasibility.In order to improve system performance in application, channel estimation technique plays a quite meaningful and challengeable role in MIMO-OFDM system. The MMSE algorithm by the pilot and the blind channel estimate algorithm is two kinds of applications more widespread channel sparameter information estimate method. But, in the practical wireless environment, the channel is changed. The conventional channel estimation because the pilot take the excessively resources, and blind estimation complexness is high, thus can not be used the time variational channel, the above method no longer will be suitable, therefore will need to track the channel in the block data the change. Therefore, in this paper, the author uses the particle filter to estimate channel sparameter information by tracking channel, this method can reduce the pilot length by improve the channel and reduce the complex.Otherwise, MIMO-OFDM system brings the huge capacity as well as high complexity of the receive signal detection. Sphere decoding algorithm is a detection algorithm with optimal performance and medium complexity. However, the sphere decoding algorithm can not solve the system where there are more transmit antennas then the receive antennas. Therefore, we propose an improved sphere decoder to decode in MIMO-OFDM system; this method can reduce the complex and keep the performance of systems.In conclusion, through theoretical analysis and simulation result, this paper can solve channel parameter information cannot accurately estimate to the time variational channel and solve the general sphere decoder can not decoding when the system where there are more transmit antennas then the receive antennas.