Closed BER of STBC-MIMO-OFDM systems over nonlinear frequency selective channel and cancellation technique for HPA distortion

Multiple-input multiple-output (MIMO) technology and orthogonal frequency-division multiplexing (OFDM) can be combined to design a robust communications scheme with increased spectral efficiency and system capacity. To reach high power efficiency, MIMO-OFDM systems are equipped with high-power amplifiers (HPA). When it operates near its saturation region, the HPA causes nonlinear distortions. Unfortunately, the nonlinearity of HPA has a crucial impact on the global system performance. In this paper, we focus on the effect of the HPA nonlinearity on the space-time block coded (STBC) MIMO-OFDM systems. Analytic expression of the average Bit error rate (BER) is delivered running under frequency selective channel. We also note an excellent agreement between analytic expressions and Monte Carlo simulation curves. In addition, this work introduces a new iterative cancelation technique for the nonlinearly detected by the receiver. The new proposed approach is based on the Bussgang theorem and consists in iterative estimation and annulation of the nonlinear distortion caused by the high power amplifier of the transmitter.