The Research And Implementation Of Multi-User Pre-Coding Algorithm In MIMO System

As wireless communication systems develop rapidly and the number of users grows exponentially, the demands for a faster speed and a greater number of users have become increasingly urgent. Pre-coding, as one of the key technologies of multi-user MIMO system, could effectively increase the channel capacity and eliminate multi-user interference, which is of great research significance. Assuming that there is a limited feedback from the system, this thesis mainly explores the following aspects of multi-user MIMO system.Firstly, a description of the channel capacity of the single-user and multi-user MIMO has been presented. Also, there is an introduction of the limited feedback multi-user MIMO system and three channel quantization algorithms, including RVQ, scalar quantization and UBQ.Next, the thesis builds a channel model of limited feedback multi-user MIMO system, analyzes the channel capacity of the limited feedback system, and researches the algorithms, channel capacity of zero-forcing pre-coding, PU2 RC and single user beam-forming with a theoretical analysis. With the help of MATLAB, three types of typical pre-coding models are built. In addition, under several simulation condition, a thorough analysis of the performances of zero-forcing pre-coding, PU2 RC, and single user beam-forming is illustrated and the algorithm complexity and implementation cost are discussed as well. Besides, with a combination of pre-coding and channel quantization theory of RVQ, scalar quantization, and UBQ, a simulation model is built. Furthermore, this thesis also compares and contrasts the system capacity and performance under the condition of different CQI feedback and user selection algorithms.Last, considering both performance and complexity of pre-coding algorithm, this thesis chooses zero-forcing algorithm to be realized on the platform of FPGA. In accordance with the requirement of zero-forcing algorithm, the system parameters are set and the multi-user pre-coding algorithm is implemented and verified on the FPGA platform. The core of zero-forcing algorithm are matrix multiple module and matrix inversion module. And the implementation of both modules is explored in detail. Moreover, the performance of matrix inversion module is analyzed with the help of MATLAB and Modelsim. And the performance of pre-coding algorithm is substantiated after the test on hardware.