Adaptive frequency domain equalizer design for SC-FDE

Thanks to the development of communication technologies, today's communication systems reached high levels of speed, as such they are able to deliver Gb/s connection speed per user. However, by reaching such a high level of speed, intersymbol interference, which is one of the most important problems affecting the reliability of communication becomes more serious. This intersymbol interference adversely affects system performance. Traditionally, time domain equalizers are used to solve this problem. However, one of the most serious disadvantages of time domain equalizers is tremendous increase in the computation of equalizer coefficients with the increase of communication speed. Equalization could be performed in frequency domain instead of time domain to solve this complexity problem. As a result of improvement in processor technology and thanks to the fast Fourier transform method, the complexity level of equalization is decreased remarkably. Besides, implementing equalization in frequency domain has the effect of performance increase compared to time domain. In this work, new frequency domain adaptive equalizer structures are developed. Both, linear and decision feedback equalizer structures are considered. In developing these structures, correlation between neighbor frequency points are utilized and due to this correlation it is shown that, developed equalizer's performance are greatly enhanced compared to other proposed algorithms in past. As a last thing, a new frequency domain decision feedback algorithm is proposed. This algorithm has 5dB signal to noise improvement compared to newly proposed counterpart. Also, it has 9dB improvement over linear equalizer structures as a a result of research activities. Proposed algorithms are shown to have some complexity level rise compared to traditional ones but this level is affordable, considering performance benefits. When comparing complexity level of newly proposed frequency domain decision feedback equalizer, our proposed algorithm has similar complexity. That is why, it is believed that proposed algorithms are possible options that could be used in broadband wireless communication systems.