All-Optical Relaying FSO Systems Using EDFA Combined With Optical Hard-Limiter Over Atmospheric Turbulence Channels

Abstract

In this paper, a novel relaying technique is proposed to improve the bit-error rate (BER) performance and distance coverage of high-speed all-optical free-space optical (FSO) communication systems. Particularly, an optical amplifyand-forward (OAF) relaying technique using erbium-doped fiber amplifier (EDFA) combined with optical hard-limiter (OHL) is introduced. The use of OHL enables EDFA-based OAF relaying FSO systems to prevent the accumulation of amplified background noise, which significantly degrades the system performance when deploying multiple relays. For performance evaluation, we theoretically analyze the proposed system over atmospheric turbulence channels modeled by Gamma-Gamma distribution. A closed-form expression for the end-to-end BER bounds is therefore analytically formulated, taking into account other impacts of atmospheric channels including atmospheric attenuation and geometric spreading of the optical beam, as well as noises caused by background light and receiver. The numerical results, which are validated by Monte-Carlo (M-C) simulations, confirm the superiority of the proposed system in comparison with conventional ones.Index Terms-Optical amplify-and-forward relaying, optical hard-limiter, EDFA, background noise, atmospheric turbulence, channel loss, FSO communication systems.

Adaptation of Mode Filtering Technique in 4G-LTE Hybrid RoMMF-FSO for Last-Mile Access Network

“…The far field delay different mode groups in the same way, therefore, a clear FSO channel can be modelled as a summative attenuation. A FSO channel state h representing the optical intensity fluctuations due to the atmospheric loss, turbulence-and misalignment-induced fading is defined as [9]:…”

“…Note that, we have assumed no misalignment induced losses. hl is a deterministic parameter and therefore is considered as a constant scaling factor over a long time scale compared to the bit intervals of ~10 -9 s [24], which is given by [9]:…”

“…where A = π(a/2) 2 is the Rx aperture area, a is the Rx aperture diameter, θ is the divergence angle, di is the FSO span, and βl is the atmospheric attenuation coefficient, which is ~0.43 dB/km for a clear channel condition [9]. ℎ is time-variant factors, exhibiting variations in the fading channel in the order of milliseconds, in which their stochastic behaviour is described by their respective distributions [25].…”

“…This technology is referred to as radio-over-FSO (RoFSO), which offers high bandwidth, immunity to the electromagnetic interference, and free license fees compared to RF wireless communications. At present, commercial FSO products offer data rates up to 10 Gbps (e.g., TereScope 10GE produced by MRV [9]). Higher data rate of 1.6 Tbps using a single FSO link was reported experimentally in [10].…”

Performance of Free-Space QKD Systems Using SIM/BPSK and Dual-Threshold/Direct-Detection

“…in which A = π(D/2) 2 is the area of the receiver aperture with D is the diameter, θ is the angle of divergence, β l is the attenuation coefficient, and L is the transmission distance in kilometers [16]- [17].…”