Calibration of Nonlinear Crosstalk in MIMO Transmitter
Abstract: output (MIMO) techniques have been extensively used in Multiple-input multiple-output modern wireless communications. The front-end front end nonlinearity coupled with crosstalk in a MIMO transmitter is much more complex than that in a single-input single single-output output (SISO) system. In this paper, we propose a nonlinear crosstalk calibration algorithm with the corresponding reference signal design. We start with the nonlinear crosstalk model of the MIMO transmitter transmitter and derive its corresponding inverse compensation model. The proposed model characterizes the nonlinearity and the crosstalk in separated blocks. We then propose specifically designed reference signals that utilize the model structure. The nonlinear crosstalk rosstalk model can be reorganized and simplified with the reference signal. Thus, the complexity of the model coefficients estimation is greatly reduced without compromising the model accuracy. In addition, with the proposed algorithm, the compensation of the nonlinearity and crosstalk can be done separately. Simulations show a satisfactory calibration results with low computational complexity.