MIMO-OFDM System Key Technology Research And FPGA Design

Orthogonal frequency division multiplexing(OFDM) system have been widelyused in high-speed data transmission with high spectrum efficiency, resistance tofrequency selective fading, anti-inter-symbol interference, etc. Multiple-input andMultiple-output(MIMO) technology uses multiple antennas can increase the channelcapacity, in the same bandwidth and transmission power. MIMO-OFDM system canbe effective against multi-path MIMO technology, effects and effective againstfrequency selective fading with OFDM technology. MIMO-OFDM techniquescombining Space-time coding techniques can combining space diversity, frequencydiversity and time diversity. Therefore, MIMO-OFDM technology is considered a hotkey of the next generation of communication systems.First, the basic principles of MIMO-OFDM system is introduced, aMIMO-OFDM system channel model is hold up. A precoding design on multi-userMIMO downlink transmission system based on Particle Swarm Optimizationarithmetic is proposed. The scheme is measured by the minimum symbol errorprobability. The average symbol error probability structured by the precoding matrixand channel information of users, then search the precoding matrix in permitted rangebased on Particle Swarm Optimization arithmetic. A time-varying channel estimationmethod based on the particle swarm optimized particle filter is proposed forMIMO-OFDM system uplink transmission. For against the problem of poor particle,the particle filter is optimizatied by particle swarm optimization, and to maintain theparticle diversity fair propotion resampling is used in proposed method, then use theinproved algorithm in channel estimation. The estimation process is carried out in thefrequency domain, so no need to know the length of the multipath channel.Secondly, the base-band of MIMO-OFDM system is designed use FieldProgrammable Gate Array(FPGA) based on MIMO-OFDM system model. This sectionintroduces the FPGA’s structure of ALTERA Cyclone series and development process.Then designed all the FPGA modules in detailed, contained serial to parallel module,QAM modulation module, space-time block coding, OFDM modulation and add cyclicprefix module. In order to verify the correctness of the results of the basebandprocessor, final designed a joint test of the software platform of hardware and software in the paper. The platform receive the results come from base-band processor throughEthernet interface.The platform baseband processor via an Ethernet interface, theresults will be sent to the PC through the network machine, a software designed in VC++6.0through a network of data receiving and processing of the interface that cansend raw data to the FPGA, FPGA processing then the results sent to the PC, andcompared with software processing of the results.