Capacity analysis of MIMO-OFDM Decode-and-Forward (DF) relay networkin the presence of high power amplifiers nonlinearity

This paper presents the ergodic capacity of nonlinear MIMO-OFDM Decode-and-Forward (DF) relay network.Nonlinearities in wireless communication channels can arise at the transmitter or the receiver side. In this work, we focus on the transmitter-side nonlinearities induced by the High Power Amplifier (HPA), the last stage in the communication chain at the base station (BS) and the relay stations (RS's). We consider MIMO-OFDM relaying system where the BS, RS's, and the mobile stations (MS's) are all equipped with N_r transmitting and N_r receiving antennas, and HPAs at the BS and RS's exhibit general nonlinear behaviors. We derive closed-form expression for the ergodic capacity of the DF relaying protocol. Our results show that highorder MIMO systems suffer more capacity loss due to HPA nonlinearity than low-order MIMO systems, and that more capacity loss is experienced in multihop relaying over nonlinear channels as more relay hops are involved.