Performance Enhancements of MIMO-OFDM System Using Various Adaptive Receiver Structures

In wireless communications, multi-channel transmission is utilized to obtain high capacity and better throughput efficiency. Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) is considered as spectrally efficient system to achieve high throughput communications. This paper investigates the performance enhancement of MIMO-OFDM system using NLMS, variable step-size NLMS and RLS adaptive receivers. The performances of using fixed step-sizes were investigated and an optimum value was chosen, based on a trade-off between the convergence speed and the steady state noise floor for NLMS algorithm and was compared with the variable step-size NLMS. The mean-square-error (MSE) performance of the proposed variable step-size approach was compared with that of fixed stepsize, which shows an excellent convergence speed and steady state performance. In addition to that, the RLS algorithm was compared with the NLMS and variable step-size NLMS. Also, the bit-error-rate (BER) of the proposed receivers was compared with that of the conventional receiver.