Analysis of variation in filter length on the performance of blind equalization algorithms

Abstract

Unsupervised equalizers found its use in bandwidth hungry applications (wired, wireless or optical). These equalizer show non-linear behavior in their error functions that are used to update the filter weight coefficients which makes it challenging in order to evaluate their performance in terms of ISI. In this paper, we present the performance analysis of a blind equalizer by varying its taps/length in order to optimize inter symbol interference (ISI) efficiently. Two algorithms are used for blind equalization in a modern wireless communication system i.e. Multimodulus algorithm (MMA) and Square Contour algorithm (SCA) respectively. The channel selected for simulation is frequency selective and time invariant in nature. The performance metrics are average ISI and bit error rate (BER). The overall performance is degraded in terms of average ISI by increasing filter taps using MMA and SCA as a blind equalizer. MMA is more powerful, stable and robust algorithm in terms of low SNR regimes and for increased filter length as compared to SCA respectively. The performance of MMA and SCA algorithms show similar performance behavior initially but for higher filter length, the performance of SCA is going to degrade keeping the same SNR regime.