Mimo Broadcast Channel Pre-coding Techniques To Study

This thesis discusses precoding technology for multi-user wireless broadcast channels in Multiple Input Multiple Output(MIMO) system, which means multiple antennas employed at both the transmitter and the receivers. This paper shortly introduces the phylogeny, the basic principles and the technical advantages of MIMO and MIMO precoding, then presents the characters and the kinds of wireless chan-nel.The Space Diversity technology in fast fading channel and the capacity of MIMO are also analyzed, and then three main parts of this paper will be given.In the whole of paper, we will suppose that the channel information between the transmitter and each user are known perfectly at transmitter and the condition will be the Rayleigh flat fading channel. In the first part of the thesis, we will discuss transmit filters which is also called linear precoding. Three linear precoding schemes are designed to be compared with three receive filters, we also get a conclusion that precoders not only simplify the receiver's design, but also make the same performance with the receiver filters or better than them.In the second part of the thesis, we introduce a non-linear precoding scheme, Tomlinson-Harashima precoding(THP) with a per-user power constraint, including zero forcing THP(ZF-THP)and Wiener THP(WF-THP), we also compare the MSE and BER performance of ZF-THP with WF-THP. Because THP is the base of vector precoding(VP), we only introduce VP briefly. We also develop a MMSE precoding method to minimize the total transmit power, which is also called uplink-downlink duality arithmetic.In the third part of the thesis, we combine Orthogonal Frequency Division Mul-tiplexing(OFDM) and MIMO to overcome the frequency selective fading. We also employ the MMSE precoding method and the uplink-downlink duality arithmetic to analyze the performance of MIMO-OFDM system. At the end of this chapter, we compare the MSE performance of MIMO-OFDM with THP.At last, we sum up the contributes and the content of this paper, and also present the research orientations in the future.