Multihop Free-Space Optical Communications Over Strong Turbulence Channels

Abstract

In this paper, we study the performance of multihop free-space optical (FSO) wireless systems over turbulenceinduced fading channels. The analysis is carried out for systems employing amplify-and-forward (AF) or decode-and-forward (DF) relays and for turbulence channels which can be modeled by the Gamma-Gamma distribution. An exact analytical expression for the end-to-end outage probability of AF systems is obtained, while a closed-form expression of DF systems is derived. The average bit-error probability of a dual-hop FSO system employing a DF relay is studied as a special case. Numerical examples are also presented to illustrate the proposed analysis and to further investigate the effects of the turbulence severity on the multihop FSO systems' performance.

On the Performance of Multihop Heterodyne FSO Systems With Pointing Errors

“…Multihop relaying, where several intermediate terminals relay the signal from the source terminal to the destination terminal, has gained significant research attention as an efficient technique mainly because it can expand the coverage of wireless networks with low power requirements while offering high data-rate at the end-to-end communication [1]. On the other hand, free-space optical (FSO) communication is a cost effective and wide bandwidth access technique operating at the unlicensed optical spectrum that allows higher capacity and higher data rates relative to the traditional radio frequency (RF) transmission [2], [3].…”

“…In [1], the outage probability of a multihop FSO system with amplify-and-forward (AF) or decode-and-forward (DF) relays over strong turbulence fading channels is studied. Relay-assisted transmission over Log-normal turbulence-induced fading with path loss has been investigated in [5].…”

Multihop Relaying Over IM/DD FSO Systems With Pointing Errors

“…Selection combining (SC) and maximum ratio combining (MRC) diversity techniques for a dual-branch transmission system composed of a direct RF link and a dual-hop fixed gain relay RF/FSO system are investigated in [9]. In [6], the outage probability of a multihop FSO system with amplifyand-forward (AF) or decode-and-forward (DF) relays over strong turbulence fading channels is studied. Relay-assisted transmission over Log-normal turbulence-induced fading with path loss has been investigated in [10].…”

“…Multihop relaying, where several intermediate terminals relay the signal from the source terminal to the destination terminal [6], can be used over FSO links to mitigate turbulenceinduced fading and, hence, increasing the reliability of the FSO link. It is an efficient technique to expand the coverage of wireless networks with low power requirements and offer high data-rate at the end-to-end communication.…”

Efficient Simulation of the Outage Probability of Multihop Systems

“…Capitalizing on these results, they determined the outage and error performance of two-hops system with regenerative and nonregenerative relays over Nakagami-m fading channels. In [5], Tsiftsis et al determined analytical expressions for the end-to-end outage probability of multihop FSO wireless systems using amplifyand-forward (AF) or decode-and-forward (DF) relays over Gamma-Gamma turbulence channels. In [6], the authors studied the performance metrics, such as the outage probability, the outage capacity and the average bit error probability of amplify-and-forward multihop systems.…”