ABSTRACT

The paper compares the performance of an adaptive linear equalizer and adaptive MMSE DFE. In mobile communication, intersymbol interference (ISI) caused by multipath in bandlimited (frequency selective) time dispersive channels distorts the transmitted signal, causing bit errors at the receiver. ISI has been recognized as the major obstacle to high-speed data transmission over wireless channels. Equalization is a technique used to combat ISI. Linear adaptive equalizers do not perform well on channels, which have deep spectral nulls in the passband. As a more powerful receiver algorithm, we prefer a decision feedback equalizer (DFE), which has better immunity against the spectral channel characteristics. In the paper, we have investigated various adaptive equalizers using the recursive least-squares (RLS) algorithm for wireless communication systems. In that regard, both linear equalizer and non-linear DFE with RLS algorithm have been examined in multipath fading channel model. We have also examined the influence of some important parameters, such as a tap number of the adaptive equalizers, and forgetting factor of the algorithm. Simulation results show that DFE perform much better than adaptive linear equalizer. Further the theoretical results have also been verified through computer simulations.