Research On Joint Detection Algorithm Of MIMO-OFDM System

The MIMO-OFDM system is regarded as the perfect choice for future high-data-rate wireless communications, because it can grow system capability exponentially without increasing bandwidth and resist the effort of frequency-selective fading. However, the performance of MIMO-OFDM system may be seriously degraded by ICI. So it is important to research on joint detection (JD) in MIMO-OFDM system.Firstly, this paper introduces the basic models and principles of MIMO and OFDM techniques, analyses the capacity of MIMO system, discusses the space-time preprocessing technique of MIMO systems, and then sets up the data transmission model of multi-user MIMO-OFDM system, and describes several different ways for OFDM technology union with MIMO technology. This paper also researches on linear joint detection algorithms, focusing on several classic algorithms: zero-forcing block linear equalizer (ZF-BLE); zero-forcing block decision feedback equalizer (ZF-BDFE); minimum mean-square-error block linear equalizer (MMSE-BLE); minimum mean-square-error block decision feedback equalizer (MMSE-BDFE) and parallel interference cancellation based on MMSE-BLE (MMSE-PIC). Then this paper introduces joint detection algorithms based on QR decomposition. The above-mentioned joint detection algorithms are applied in MIMO-OFDM systems, in order to obtain the simulation curves of system performance and analyze the performance of various algorithms.The key point of this paper is that after studying the existing joint detection algorithms based on QR decomposition and analyzing the characteristics of MIMO-OFDM system interference, propose to amend the existing joint detection algorithms, resulting in a new joint detection scheme (QR-ML). Simulation results show that the revised joint detection scheme can improve system performance, and increase system capacity.