Performance of CP-free ST-BC MIMO-OFDM system under IQ-imbalance in multipath channel

The CP-free MIMO-OFDM system is considered to be an alternative to improve the spectral efficiency of the CP-MIMO-OFDM system. In this paper, we investigate the performance of the CP-free ST-BC MIMO-OFDM system under the effects of non-linear distortion due to HPA in the transmitter, and IQ-imbalance in the receiver. We first show that with the ST-BC encoder the constraint of the CP-free MIMO-OFDM system can be removed and back to the basic requirement of MIMO system. After compensation of the IQ-imbalance in the receiver, an equalizer under the framework of generalized sidelobe canceller (GSC) is derived for interferences suppression, and the partially adaptive (PA) array scheme is applied for complexity reduction. Simulation results show that the proposed scheme can perform very close to that with the idea CP-based ST-BC MIMO-OFDM system, and outperforms the one without compensation.