Interference Suppression In MIMO-OFDM Communication Systems

To satisfy people’s expectation of future communication, the fourth generation (4G) mobilecommunication system emerges. And the core technologies include OFDM and MIMOtechnologies. They have striking advantages. The MIMO-OFDM system avoids their respectiveshortcomings and making the most of their strong points. In fact, it has been widely applied in thewireless communication system.Despite the notable advantages, there still exist some problems in the actual applications ofMIMO-OFDM technology. Currently, the major problems lie in various types of interferences inthe communication process, which will severely affect system performance. To improve systemperformance means to reduce diverse interferences, which is of great significance in the system.Firstly, this thesis classifies and researches the various types of interferences and their causesin the MIMO-OFDM communication system. Secondly, through analysis and summary, itillustrates and summarizes the anti-interference algorithm and program for the communicationsystem, in particular, the carrier frequency offset (CFO) of ICI and phase noise. Finally, it builds aMIMO-OFDM mathematical model and a mathematical model of ISI, CFO and phase noise thathave great influence on system performance. As the analysis of the models shows that phase noiseover multi-path fading channel includes different interferences, this thesis puts emphasis on thetracking and correction of the phase noise based on the research on various interferencesuppressions.Phase noise in multi-path fading channel is a decisive factor affecting system performance.ISI in the process of data transmission, common phase error (CPE) caused by phase noise andinter-carrier interference (ICI) will drive up bit error rate (BER) and down signal to noise ratio(SNR).This thesis puts forward an estimation algorithm of CPE and ICI caused by phase noise inthe MIMO-OFDM system and get a sound phase noise wave approximation with an estimation offew spectral components. According to simulation analysis and comparison, the optimizedprogram suggested in the thesis is effective in improving MIMO-OFDM communication systemperformance over multi-path fading channel.