Research On Intercarrier Interference In MIMO-OFDM Systems

In recent years, a great deal of attention concentrates on orthogonal frequency-division multiplexing (OFDM) for multiple-input multiple output channels (MIMO-OFDM) due to its potential of achieving high data rates. Some facts would degradate the performance of MIMO-OFDM system, e.g intercarrier interference. Various works treat the impact of inter-carrier-interference on the performance of the OFDM system. Unlike OFDM, only a few works study the impact of intercarrier interference on the performance of the MIMO OFDM system. The carrier frequency offset (CFO), phase noise (PN) and Doppler spread give rise to intercarrier interference. The received signal would be processed by a detector whose aim is to determine the received data symbols. However, intercarrier interference has different effects depending on the type of detector. Therefore, in this paper, we will give a completely research.The phase noise at the transmit come mainly from the up-conversion by high-frequency oscillators, is assumed to the same for all the transmit antennas. The phase noise at the receive come mainly from the down-conversion by high-frequency oscillators, is assumed to the same for all the receive antennas. But the phases noises can be independent at all transmit and receive antennas. We will focus on the BER for MIMO-OFDM systems with PN using linear detectors. We will first discuss the impact of the intercarrier interference for MIMO-OFDM systems impaired by transmitter PN using ZF detectors in Rayleigh fading channels and discuss the impact of the intercarrier interference for MIMO-OFDM systems impaired by receiver PN using linear detectors in Rayleigh fading channels.In MIMO-OFDM systems, channel estimation error and carrier frequency offset are two objective existing factors. In order to investigate the effect of carrier frequency offset on the performance of MIMO-OFDM systems in the presence of channel estimation error, zero-forcing detectors and an approximation to the Wishart distribution are used to theoretically deduce the signal-to-interference-plus-noise ratio and its probability distribution for the system in the presence of estimation errors of Rayleigh and Rician fading channels, and the average error probability as well as the outage probability of the system is further obtained.The mobility in transmitter or receiver must be considered since it causes a loss of subcarriers orthogonally, leading to intercarrier interference. Several works study the inpact the velocity of transmitter or receiver on intercarrier interference, but authors cannot study impact the angle of arrival at the receiver on the intercarrier interference. Firstly the close-formed expression of intercarrier interference and SINR due to the Doppler frequency shift caused by the movement of receiver is derived base on the geometrical one-ring model. Secondly the close-formed expression of intercarrier interference and SINR due to the Doppler effect caused by the movement of receiver or transmitter are given base on the geometrical two-ring model. We show that most of intercarrier interference power comes from neighboring subcarriers. These results motivated our developments of low-complexity receivers for intercarrier interference suppression.The MIMO-OFDM system can be impaired by channels estimation error over time varying Rician channels. The performance for MIMO-OFDM systems in presence of channels estimation error is investigated using singular value decomposition detectors over time varying Rician channels. Approximation to the distribution of complex non-central Wishart distribution is used to derive probability density function of signal-to-interference-plus-noise ratio (SINR), average error probability of the system in high SINR.