Research On MIMO Multi-user Downlink Precoding

Today's society is a informationalizeded society. It's hardly to develop mobile communication technology to a higher level. Limited resources and increasing the frequency of user needs into a conflict of irreconcilable. In the future development of mobile communication, how to improve the wireless data rate is the Key issues. MIMO technology without increasing the bandwidth capacity of the whole system can be linear growing. MIMO is the important technology in the future wireless communications. MIMO channel matrix deficiency of the rank。To solve this problme using pre-coding technical.it can send the transmission sequence into M parallel sub-sequences.then multipied with the pre-coding matrix assigned ti the different trasmitting antennas.it can inhibit the MIMO channel rank deficiency of the system performance.The state of the passage introduced the Research status of MIMO technology. Especially,introduced the procoding technology and limited feedback. And the theoretical analysis of the various pre-coding scheme and the limited feedback scheme. Lack of the traditional coding scheme, Designed a new coding scheme. proposed a new TH pre-coding scheme based on the traditional TH pre-coding scheme. though the interference between users is cancelled by the joint processing of transceiver, the processing vector can be obtained without iterative computation. The proposed THP scheme has the merit that it has no constraints on receive antennas and can improve the BER performance of the system greatly when each receiver has two antennas. A limited feedback scheme which has no constraints on the number of antennas is proposed and the distribution of the normalized channel covariance matrix is given. The proposed limited feedback scheme based on the CIB precoding technique and has the advantage that its total feedback bits are independent of the number of receive antennas. In addition, because the scheme we proposed quantizes the elements of channel covariance one by one, there is no need to construct any codebook for the transceiver.