Abstract
Abstract. Equalization techniques are commonly used in low to moderate data transmission over time varying wireless mobile channels. Their use is mainly to alleviate the detrimental effect of intersymbol interference brought about by the multipath phenomena of such channels. The wireless multipath channel is time varying which makes the use of adaptive equalization a necessity to cope with channel variations and consequently to overcome resulting intersymbol interference effects, restore the transmitted symbols, and extract the information being sent. The first part of this paper presents a comparison study of the performances of four representative methods of adaptive equalization. Linear and nonlinear structures each with both LMS and RLS adaptation algorithms are used in the investigation. In the second part of the paper, a computer simulation is carried out to investigate the relationship between the number of propagation paths of the wireless mobile channel and the number of taps in the incorporated adaptive equalizer. Four equalizer structures are used in this investigation which is based on Simulink software package to simulate a communication system incorporating these equalizers. The bit error rate (BER) performance is used as a measure for establishing this dependency. 000
Highlights
The IT industries, over the last few decades, have significantly being revolutionized by the invention of internet and the application of the packet switching wireless networks
The simulation conducted in the first part of this work and the associated results obtained clearly indicate that in such time-varying environment there can be no definite relationship(s) among the structure of the equalizer, the adaptation algorithm and their impact on the performance of the communication system that uses equalization technique to alleviate the detrimental effect (i.e. Inter Symbol Interference (ISI)) which results due to multipath phenomena
The number of dominant multipath in a particular scenario intuitively recommend a particular number of taps in the implemented equalizer, the nature of the environment keeps such dominating paths not fixed in number
Summary
The IT industries, over the last few decades, have significantly being revolutionized by the invention of internet and the application of the packet switching wireless networks. Other types of impairments encountered like thermal noise, shot noise, and cross talk will negatively affect the received symbols even further This makes the use of signal processing techniques at the receiver inevitable in order to overcome the impairments inflicted on the transmitted pulses and facilitate the recovery of their information. Using a fixed pair of transmitting and receiving filters will not be adequate if designed on the basis of average channel characteristics as far as ISI is concerned. To overcome this problem adaptive equalization, as shown, is widely used. The most commonly used ones are; symbol spaced equalizer, fractionally spaced equalizer, decision-feedback equalizer, and blind equalizer [10]
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