Lte-advanced, Multi-user Mimo Precoding Method

Along with the voice and data service explosively increase, the demand for higher transmission rate and higher quality is required, so the new research of modern information technology is required in communication field.The precoding methods are the new information technologies that the transmitter pre-processes the data before it is transmitted with the CSIT. The beamforming technology based on the precoding methods have been adopted in the recent 3GPP LTE protocol.Firstly,this article combines the precoding methods with MIMO spatial multiplexing and transmit diversity, and also with bemforming of TDD-LTE baseband,then some simulaition results of the TDD-LTE baseband for the different transmit modes will be given in this article.In LTE-Advanced, the MU-MIMO technology has been enhanced, so that it can fully use the diversity gain of the MU-MIMO effectively. As the data information of users is transmitted in the same frequency-time resources, so the Co-channel inference between users can not be avoided. Therefore, in this paper, the technology which is used for the cancel of the interference between MU-MIMO, also called the precoding technology for MU-MIMO has been studied. Firstly, the tradition technologies such as BD, ZF and advanced ZF have been studied, but the disadvantage which exits in these algorithms is the total number of transmit antennas must be larger than the total number of receive antennas, so the algorithm called the maximize of SLNR has been studied. According to the simulation results, the SLNR algorithm can overcome the disadvantage of the equipment of antennas. Finally, in order to cancell the interference between MU-MIMO maxmizely, we introduce the iterative interference-cancell algorithm. According to the simulation result, compared the other algorithms, the iterative interference-cancell algorithm has some advantage in the cancel of interference between MU-MIMO.In order to improve the cell's throughput, and improve the performance of the users which belong to the edge of cell, the Coordinated Multiple Point (CoMP) transmission technology, also called the distributed MIMO technology appeared. In this paper, we have studied the precoding technology of joint transmission (JP) and Coordinated Beamforming(CBF) of CoMP.Finally, the feedback technology of MU-MIMO for LTE-Advanced single cell has been studied in this paper, we focus on the compress feedback technology of MU-MIMO such as the uniform quantize feedback technology and no-uniform quantize feedback technology. According to the simulation results, the no-uniform quantize feedback technology has advantage compared to the uniform quantize feedback technology, and as the increase of the quantize bits, the two algorithms'performance is nearly similar.