Research On Multiple Users Precoding Technology In LTE-A

Multi-antenna precoding is a specific kind of adaptive technology in multi-antennasystem. By employing auxiliary information conveyed from the backend to the frontendto pre-process the source signal, it can acquire antenna array gain, spatial multiplexinggain and transmit diversity gain. Compared with open loop MIMO, multi-antennaprecoding can improve the overall performance with probably lower receivercomplexity.According to3GPP LTE-A standard of physical layer aspects, a downlink sharechannel of LTE-A simulation platform is established, including the mostly parts ofmedia access control layer and physical layer. Then this thesis researches single userprecoding schemes, multi-user precoding algorithms with perfect and limited feedback.Allying the downlink system of LTE-A, a signal to leakage noise ratio multi-userprecoding scheme which is based on precoding matrix index feedback is proposed.Precoding matrix is calculated at BS and the backhaul is very low. The performance ofthis method approximated to the result in perfect feedback.In the last part, double codebook is investigated. A method called double codebookbased on codebook rotation is proposed in this thesis. Two codebooks of small size arecontacted by householder transform and a new codebook with plenty elements areformed. The research indicates that, at the same feedback overhead, it can obtain higherquantification precision and lower complexity. This method realizes low interferenceamong users.