Research On Precoding Technology Of Wireless Communication

The wireless mobile communication system has been developed to thefourth generation. With OFDM and MIMO these two key technologies, thesystem has much faster data rate and higher spectrum efficiency. MIMOsystems created by exploiting antenna arrays at the transceiver, offer highcapacity and high-quality wireless communication links without increasingsystem bandwidth or transmit power.However, the application of MIMO technology also encountered somedifficulties which may reduce the system performance, such as thecorrelation between the antennas, signal interference between subchannels,etc. The precoding technology as an important part of MIMO technologyapplications creates the equivalent MIMO channel which can improvesystem performance and simplify the receiver designing according to thechannel state information on the transmitter, and thus get a very wide rangeof applications.This thesis aims to discuss the precoding technology from the point ofpractical using. Firstly, we carry out mathematical modeling and quantitativedescription on MIMO precoding technology. We listed some importantfactors which have a depth impact on precoding design, and transform theprecoding designing problems to the matrix optimization problems.Then, this thesis summarizes the most widely used precoding schemesproposed by predecessors. We firstly describe optimal precoding schemes atthe situation of knowing the full channel state information. We useMajorization Theory to study the optimal solutions of different precodingcriteria. Furthermore, we introduce the most practical used precoding scheme-limited feedback precoding, which is also introduced in the4Gstandard LTE-Advanced. Limited feedback precoding scheme has twoimportant aspects: the codebook designing and the precoding matrices, andwe explain how to transform the ideal precoding criteria to the limitedfeedback precoding selection criteria.As a supplement and innovation of the existing precoding schemes, thisthesis have a depth research on precoding design with stream maximizationtransmission. We get some important conclusions, which are:1) The validity of all the common used precoding criteria have beendiscussed in the situation of stream maximization transmissionrespectively in three different precoding schemes: non-unitaryprecoding, unitary pre-coding and limited feedback precoding.2) In order to fill the gap in limited feedback precoding criteria withstream maximization transmission, we propose a new codebookselected criterion–Minimization1-norm selected criterion.3) On the basis of the work done in the previous two, we propose acomplete precoding criteria solution in stream maximizationtransmission.At last, we come to the conclusion, summarizes the contents of thisthesis and put forward some research direction for future precodingtechnology.