Research And Implementation Of MIMO Detection In WiMAX System

With the development of the wireless communication in the global, a higherdemand is put forward on the speed and quality of the communication. MIMOtechnology (Multiple Input and Multiple Output) has been adopted in manycommunication systems in order to resolve the problem that the channel capacity of atraditional communication system is limited by the Shannon theory. Not only is thefrequency spectral efficiency of the wireless communication greatly improved, but alsothe anti-fading capability of the system is enhanced by the MIMO technology, which isconsidered as an indispensable technology in the future communication system. At thesame time, as the new generation broadband wireless access system based on theIEEE802.16standard, WiMAX (Worldwide Interoperability Microwave Access),which adopts MIMO-OFDM technology in its physical layer, is widely used in theacademy and industry because of the superior performance. In view of the reasonsabove, further research on the MIMO technology utilized in the mobile WiMAXsystem is presented in this thesis as below:(1)The simulation platform of downlink is built for the two MIMO modes(transmit diversity mode and spatial multiplexing mode) supported by the WiMAXsystem in this thesis. The performance simulation maps of transmitting diversity modesin different channel conditions and modulation patterns are given, compared andanalyzed while the MIMO detection technique in the spatial multiplexing mode isspecially introduced, which adopts different methods including MMSE algorithm,MMSE-SIC algorithm and QRD-M algorithm respectively. And the QRD-M algorithmis improved by combining the QRD-M algorithm with the SIC algorithm to reduce thecomplexity of the algorithm while the channel matrix is reordered to reduce the loss ofthe algorithm performance.(2)The FPGA implementation of the improved QRD-M algorithm is presented inthe thesis. First of all, modules are divided, and each module is elaborately designedbased on the balance between speed and consumption of resource. Then, the RTLmodel for each module is built by using the Verilog HDL. Finally, the data throughputof the MIMO detector is given in the thesis, as well as the resource consumption.Through the data analysis results, the system performance is significantly enhancedbecause of the MIMO detector, which is accomplished in this thesis.