Unified Performance Analysis of Hybrid FSO/RF System With Diversity Combining

Abstract

Hybrid free space optical (FSO)/radio frequency (RF) systems have been proved to be reliable links for high-data-rate wireless backhauls. In this paper, we present a unified performance analysis of the hybrid FSO/RF transmission system which transmits the identical data in both links and implements two popular diversity combining schemes, namely, selection combining (SC) and maximal ratio combining (MRC), in the receiver. Specially, for the FSO link, the Gamma-Gamma turbulence with pointing errors under heterodyne detection (HD) and intensity modulation/direction detection (IM/DD) is considered in our analysis while the general κ-μ shadowed fading which unifies popular RF fading models is employed for the analysis of the RF link. As a result, unified closed-form expressions of outage probabilities and average bit error rates for different modulation schemes are derived. Analytical and Monte Carlo simulation results are provided to characterize the performance of the hybrid FSO/RF link which is compared to the single FSO link and the single RF link. The agreement between the analytical and simulation results confirms the unification of various FSO channels and RF fading scenarios into a single closed-form expression.

On the Capacity Performance of Hybrid FSO/RF System With Adaptive Combining Over Generalized Distributions

“…• In literature, a very few works are available on the adaptive-combining-based hybrid FSO/RF system and the performance metrics like outage and average SER were investigated over the Gamma-Gamma and Nakagami-m fading distributions [26]- [27]. Mixed FSO/RF DH with AF relay Gamma-Gamma Nakagami-m Zero boresight [13] Mixed FSO/RF DH with DF relay Gamma-Gamma Nakagami-m Zero boresight [14] Mixed FSO/RF Fixed and variable gain relay Gamma-Gamma Rician Zero boresight [15] Mixed FSO/RF AF and DF relay Double generalized Gamma EGK shadowed fading Non-zero boresight [16] Hybrid FSO/RF Soft-switching Gamma-Gamma Rician Not included [17] Hybrid FSO/RF Hard-switching Log-normal Nakagami-m Not included [19] Hybrid FSO/RF Hard-switching Malaga α-η-κ-µ Zero boresight [20] Hybrid FSO/RF Multi-hop with hard-switching Gamma-Gamma Nakagami-m Zero boresight [24] Hybrid FSO/RF MRC and SC Gamma-Gamma Rician Not included [25] Hybrid FSO/RF MRC and SC Gamma-Gamma κ-µ Zero boresight [26] Hybrid FSO/RF Adaptive combining Gamma-Gamma Nakagami-m Not included [27] Hybrid FSO/RF Adaptive combining Gamma-Gamma Nakagami-m Zero boresight computationally less exhaustive. Further, the Monte-Carlo simulations are performed to confirm the accuracy of the analytical results.…”

“…However, frequent hardware switching between FSO and RF sub-systems is a major bottleneck in the case of a hard-switching scheme and also, it requires the channel state information (CSI) at the transmitter. To alleviate these issues, the FSO and RF links of the hybrid FSO/RF system were combined using SC and MRC in [24] and [25], where transmission of feedback bits to the transmitter as well as the requirement of CSI at the transmitter are not mandatory.…”

Outage Probability Analysis of Hard-Switching based Mixed FSO/IRS-aided RF Communication

“…The hard-switching scheme was explored in a multihop scenario in [5]. Further, selection combining (SC) [6] and maximal ratio combining (MRC) [7] diversity techniques were employed in the mixed FSO/RF system. In the MRC or the SC diversity technique, both the links are activated.…”

Developing Cost-Effective and High-Speed 40 Gbps FSO Systems Incorporating Wavelength and Spatial Diversity Techniques

“…The adoption of diversity schemes not only proved to be a major cost-effective factor in improving the link reliability in FSO systems but also helps improve bandwidth capacity, quality factor (Q), and reduced latency [26][27][28]. Additional technology measures such as coherent reception, higher modulation techniques, artificial intelligence, and machine learning have also been suggested in recent literature as catalysts to enhance link performance in FSO systems; however, on the flip side, the technological intricacy and budgetary constraints of these techniques are major deterrents toward their commercial implementation [29,30]. As a wellevolved and matured technology, spatial diversity and wavelength diversity proved to be efficient measures in countering atmospheric adversities [28].…”

“…As a wellevolved and matured technology, spatial diversity and wavelength diversity proved to be efficient measures in countering atmospheric adversities [28]. Diversity schemes are also known for their ability to deliver higher throughput and low bit error rates [30]. The usage of readily available hardware, which is easy to install and comes with improved end factors, cuts down the overall cost for the setup, as the available resources are being shared for multiuser scenarios [31].…”