Performance Analysis of a Vertical FSO Link with Energy Harvesting Strategy

Abstract

In this paper we investigate the application of free space optical (FSO) communications, energy harvesting, and unmanned aerial vehicles (UAVs) as key technology enablers of a cost-efficient backhaul/fronthaul framework for 5G and beyond (5G+) networks. This novel approach is motivated by several facts. First, the UAVs, acting as relay nodes, represent an easy-to-deploy and adaptive network that can provide line-of-sight between the base stations and the gateways connected to the core network. Second, FSO communications offer high data rates between the UAVs and the network nodes, while avoiding any potential interference with the 5G radio access networks. Third, energy harvesting in the optical domain has the potential to extend the UAVs’ battery life. Nevertheless, the presence of atmospheric turbulence, atmospheric attenuation, and pointing errors in the FSO links severely degrades their performance. For this reason an accurate yet tractable modelling framework is required to fully understand whether an UAV-FSO backhaul/fronthaul network with energy harvesting can be applied. To this end, we consider a composite channel attenuation model that includes the effect of turbulence fading, pointing errors, and atmospheric attenuation. Using this model, we derive analytical closed-form expressions of the average harvested energy as a function of the FSO link parameters. These expressions can be used to improve energy harvesting efficiency in FSO link design. We have applied our proposed expressions to evaluate the energy harvested in vertical FSO links for a variety of real scenarios under a modified on-off keying (OOK) scheme optimized for energy harvesting. From the simulations carried out in this paper, we demonstrate that significant values of harvested energy can be obtained. Such performance enhancement can complement the existing deployment charging stations.

Establishing a Spectral Optical CDMA System Involving the Use of Two Mutually Orthogonal States of Polarizations Using 1-D Two-Distinct Codes With Two-Code Keying

“…The overall output current of the receiver is determined as cc(h, g)cc(h', g'). In summary, the output current of the receiver is proportional to (δ+1) for ib = 0 ⋂ h = 0 ⋂ g = 0, -(δ+1) for ib = 1 ⋂ h' = 0 ⋂ g' = 0, and otherwise as specified in (9). This arrangement allows the proposed receiver to successfully recover the desired data while effectively eliminating MUI.…”

Flexible Free-Space Optical CDMA Networks

“…Moreover, the transmitted signal is subjected to scintillation due to atmospheric turbulence, hence the irradiance power, I , is considered a random variable with P b (e) denoting the ABER. Assuming a Gaussian distribution for the MAI [14], then the error probability of the OCDMA fiber channel is averaged over the GG PDF shown in (7) in its generic form (or in (10) and (11) for the two particular scenarios) as:…”

“…Then, Equation ( 24) is solved for the three cases represented by Eqs. ( 7), (10) and (11), and to do so, we employ the equivalences between the Meijer-G and Bessel K functions [41,Eq. ( ] to solve the resulting integral involving the product of two Meijer-G functions.…”

“…FSO communications benefit from unregulated bandwidth available in optical frequencies, enabling data rates as high as those in PON [7]- [9]. Consequently, successful implementation of FSO systems occurs in not only access networks but also cellular fronthaul [4] and backhaul [10], along with various other intriguing scenarios [8], [11].…”

Beyond 5G Fronthaul Based on FSO Using Spread Spectrum Codes and Graphene Modulators

“…The need for the fast and efficient broadband service provision to support the traffic supply and demand in ultra-dense urban areas grants FSO technologies a potential to become a viable alternative for the fronthaul mobile cells densification. The large interest in FSO [38][39][40][41][42][43][44] is mainly due to its immunity to the radio interference, license-free operation, and optical broadband availability which render this wireless technology as a strong candidate for the deployment of broadband mobile fronthaul systems. FSO has higher security levels than have the main competing technologies such as optical fibers [45][46][47], albeit with some vulnerabilities to eavesdroppers as suggested in Ref.…”