Abstract
Wireless communication system has a great impact in the world of telecommunication and is expected to be a leading role in the developing a nation. However, the system is characterized by multipath propagation effects that lead to signal fluctuation at the receiver, thereby degrading the performance of the system. Maximal Ratio Combiner (MRC) being used to address this problem is characterized with hardware complexity that results in long processing time. Therefore, in this paper enhancement of MRC with closed form expression over Log-Normal fading channel is carried out using Firefly Algorithm (FA) at the receiver. FA create a flashing light in associated with Signal to Noise Ratio (SNR) of the received signal and output the signal with highest SNR. Randomly generated bits used as source data are modulated using M-ary Quadrature Amplitude Modulation (M-QAM) and transmitted over Log-Normal fading channel to generate resultant signals. The resultant signals at varying paths ‘L’ (2, 3, 4) are optimized by FA. The outputs of the FA are combined by MRC to obtain the received signal and converted to baseband through demodulation. A mathematical expression using the Probability Density Function (PDF) of Log-Normal fading channel at varying paths ’L’ for Bit Error Rate (BER) is also derived. The technique is simulated using MATLAB 7.4. The performance is evaluated using Signal-to-Noise Ratio (SNR), Bit Error Rate (BER) and Processing Time (PT). The result shows that, the enhanced MRC (eMRC) gave lower BER values when compared with conventional MRC with reduction in hardware complexity. The eMRC carried out can be used to enhance the performance of wireless communication system.
Highlights
Wireless Communication (WC) is the exchange of information between two or more users that are not connected by an electrical conductor [3]
The Bit Error Rate (BER) values obtained for the enhanced Maximal Ratio Combiner (MRC) are 1.25ee−6, 1.84ee−7, 2.66ee−8 at Signal to Noise Ratio (SNR) of 4, 6, 8 dB, respectively as against the conventional MRC with BER values of 2.51ee−6, 3.69ee−7, 5.33ee−8 at SNRs of 4, 6, 8 dB, respectively
At SNR of 2, 4, 6 dB, the BER values obtained for enhanced MRC are 5.01ee−6, 7.72ee−7, 1.13ee−7 as against the conventional MRC of 1.00ee−5, 1.54ee−6, 2.25ee−7, respectively
Summary
Wireless Communication (WC) is the exchange of information between two or more users that are not connected by an electrical conductor [3]. The system used to process the information to be transmitted through space consists of transmitter, receiver and the channel through which signal propagates. Transmitter encode, modulate and filter the information to be transmitted before propagating through the space. Wave propagation refers to the behaviour of signal when they are propagated from transmitter to receiver. Multipath propagation is a phenomenon that occurs when a transmitted signal propagates in multiples as a result of obstruction in terrestrial environment that results in radio signals reaching the receiving antenna by two or more paths. Transmitted signal resulted into varying signal with fluctuation in strength at the receiver due to multipath fading. The received signal varies with time, geographical position or radio frequency, causing poor reception of the signal and degrades the performance of the system. Fading compensation is required to mitigate this effect [9]
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