Analysis of nonlinear crosstalk impairment in MIMO-OFDM systems

An analytical modeling and performance analysis for a multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) transceiver exhibiting crosstalk and nonlinear distortion in transmitting chain is presented. For this purpose, a two-dimensional memory polynomial is used to describe the dynamic nonlinear MIMO transmitter. It is shown that the impairment of nonlinear crosstalk can be characterized by two complex attenuations and a nonlinear additive noise. Moreover, an analytical formulation for the symbol error rate (SER) of MIMO-OFDM system considering a frequency selective channel is provided. Experimental results have been employed to extract a realistic model for the nonlinear transmitter in the presence of crosstalk. Also, a model of the linearized transmitter has been calculated after experimentally applying digital predistortion (DPD). The proposed model for the system is validated by the simulation results and a good agreement between the analytical and simulation results is observed. Finally, it is shown that nonlinear crosstalk degrades SER of the system, whereas, the DPD can effectively compensate for the nonlinearity and crosstalk infections, which, in turn, improves SER of the MIMO-OFDM system.