Enhancing the Spectral Efficiency of an Uncorrelated Nakagami-M Fading Channel using a Modified Selection Combining Diversity Scheme

K. A. Ibrahim, A. D. Usman, S. M. Sani, H. Bello, Agbon E. E.

Abstract


Wireless communication system has found worldwide acceptability in providing acceptable signal level due to its portability, flexibility and ease of usage. However, the system is characterized by severe multipath propagation effects that degrade its performance. Selection Combiner (SC), as one of the techniques being used to address this problem has a poor performance with low Spectral Efficiency (SE) and high Bit Error Rate (BER) due to fixed transmitting power used in the system. Hence, in this paper, an enhanced SC that adjust the transmitting power based on Channel State Information (CSI) with a closed form expression over an uncorrelated Nakagami-0.5 fading channel is proposed. The proposed technique is developed using the conventional SC (CSC) and feedback algorithm. The multiple copies of transmitting signal over an uncorrelated Nakagam 0.5 fading channel are received using multiple antennas. The resultant signals at varying paths ‘L’ (2, 3, 4) were scanned by SC to choose a path with the highest Signal to Noise Ratio (SNR). The output of SC which is a function of Channel State Information (CSI) acquired was used to determine the channel gain. The transmitting power was then adjusted based on the value of channel gain through feedback algorithm. A mathematical expression for BER and SE were also derived. The proposed technique was simulated using Matrix Laboratory R2018a and evaluated using SE and BER by comparing with each of Optimal Rate Adaptation (ORA) and Channel Inversion Fixed Rate (CIFR) to determine the performance of the system. The results obtained revealed that, the proposed technique show percentage reduction in BER of 33.33% and 66.67% when compared with ORA and CIFR, respectively. While, the proposed technique shows an increased in SE values by 32.14% and 54.17% when compared with ORA and CIFR, respectively. The study showed that the proposed technique gave lower BER values and high SE when compared with ARA and CIFR due to self-adjustment of the transmitting power. Therefore, the proposed technique can be deployed to improve the performance of wireless communication systems.     

 


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References


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