Analysis and Comparison of Compensation Techniques of HPA Nonlinearity in Multi-User MIMO OFDM Systems using MMSE Receiver

The combination of Multiple Input Multiple Output (MIMO) with Orthogonal Frequency Division Multiplexing (OFDM) is a promising technique for high performance with very high data rates in 4G broadband wireless communications. However, the non-linearities caused by the High Power Amplifier (HPA) degrade the performance of MIMO-OFDM systems. In this paper, we present a theoretical analysis of nonlinear (NL) distortion effects in a MIMO-OFDM system in terms of error probability and system Capacity. Then, two compensators for reducing the distortion are proposed. The first is based on neural networks and the second is an iterative technique called Power Amplifier Nonlinearty Cancellation (PANC). These techniques correct the nonlinear distortion effects on the received signal, accompanied with MMSE detector. This receiver has shown best performance comparing to other receivers [1]. Simulation results show the comparison between the theoretical and simulated of nonlinear distortion effects in MIMO-OFDM transmission systems, as well as the performance of different compensators.