Combating performance degradation in optical channels using successful noise reduction adaptive equalizer

Abstract

Optical communications either wire or wireless are a promising candidate to support multimedia such as: “local area network (LAN), wide area network (WAN), metropolitan area network (MAN), wireless optical microwave link for TV and broadcast as well as the inter satellite link communications”. Where, they have substantial advantages such as ultra high bit rate, extremely high speed, secure and immune communications. However, its high-speed data transfer, transmission distance and bandwidth often limited by pulse dispersion which causes pulse brooding and hence signal distortion or inter symbol interference (I.S.I). The current paper, proposes an adaptive equalizer by integrating the fractional spaced equalizer (FSE) with decision feedback equalizer (DFE) for optical channel to remedy the problem of pulse dispersion effect in optical link, in addition, for further improvement in the performance of the equalizer we propose adopting the activity detection guidance (ADG) with tap decoupling (TD) in the fractional spaced decision feedback equalizer (FSDFE) to get fruitful outcomes in the performance of the system without shortcomings. Where, we could improve the stability, the steady-state error performance and the convergence rate. A typical optical channel will be analyzed; channel equalization will be performed using the addressed structures of adaptive equalizer. Numerical results have been carried out using a careful choice for the parameters which affect the equalizer performance such as: noise variance has been set at 0.1 and the adaptation step size has been set at 0.005 and the adaptation of FSDFE has been run for 30000 sample input. The simulation results revealed that: the FSDFE with ADG and TD offers a superior performance than its counterpart without ADG and TD. Where, it offers improvement in the effectiveness of amplitude distortion. Moreover, as the impulse response of a typical optical link would have regions that are essentially zero, the employment of the ADG scheme would further enhances the steady-state error performance and convergence rate.