Enhancing performance in hybrid FSO/RF communication systems under atmospheric turbulence and pointing errors

The continuous progress in hybrid free space optical/radio frequency (FSO/RF) communication systems has led to their significant potential in addressing the challenges posed by atmospheric turbulence and pointing errors. This paper investigates the strategy for improving the performance of such hybrid systems under these adverse conditions. By employing adaptive modulation and combining techniques, the system adapts to the fluctuating quality of the FSO link due to atmospheric turbulence and the effects of pointing errors. The utilization of exponentiated Weibull (EW) and Rician distributions accurately models the fading in FSO and RF channels, respectively. Through rigorous analysis, this study establishes closed-form expressions for outage probability and average bit error rate (BER), providing insights into the system's performance. Furthermore, the study investigates the influence of various parameters, including the FSO and RF link's SNR, turbulence conditions, and pointing error parameters, on system performance. The results demonstrate a significant enhancement in system performance. Specifically, for an outage probability of 10(-2), the proposed scheme improves performance by 6 dB compared to the FSO link and by 7 dB compared to the hard-switching scheme. Furthermore, at an SNR of 10 dB, the proposed scheme enhances the BER system performance by 10(-5) and 10(-8) compared to hard-switching and the FSO link, respectively. The implementation of adaptive modulation improves the BER system performance by a factor of 10(-5) compared to using BPSK modulation. Hence, the proposed system boosts the quality of service (QoS) by a factor of 99.99%.