Current optical technologies for wireless access

The objective of this paper is to describe recent activities and investigations on free-space optics (FSO) or optical wireless and the excellent results achieved within SatNEx an EU-framework 6th programme and IC 0802 a COST action. In a first part, the FSO technology is briefly discussed. In a second part, we mention some performance evaluation criterions for the FSO. In third part, we briefly discuss some optical signal propagation experiments through the atmosphere by mentioning network architectures for FSO and then discuss the recent investigations in airborne and satellite application experiments for FSO. In part four, we mention some recent investigation results on modelling the FSO channel under fog conditions and atmospheric turbulence. Additionally, some recent major performance improvement results obtained by employing hybrid systems and using some specific modulation and coding schemes are presented

Experimental study of bit error rate of free space optics communications in laboratory controlled turbulence

This paper reports experimental results for the performance of an free space optical (FSO) communication link employing different modulation schemes under the influence of the atmospheric scintillation. A dedicated experimental atmospheric simulation chamber has been developed where weak and medium turbulence can be generated and its effect on the FSO link is investigated. The experimental data obtained is compared to the theoretical prediction. The paper also shows that the effect on the data transmission performance depends on the position of turbulence source positioned within the chamber

Performance of free space optical communication using M-array receivers at atmospheric conditions

Abstract: In free space optical (FSO) communication links, atmospheric parameters including absorption, scattering and turbulence have significant impacts on the quality of laser beams propagating through the atmosphere. Absorption and/or scattering, due to atmospheric particles result in optical losses, whereas turbulence contributes to the intensity scintillation that can severely impair the operation of FSO communications systems. In this paper, using a modified model we analyze the atmospheric effects on the signal-to-noise ratio (SNR) and the bit error rate (BER) of an FSO system. We show that there is an improvement in BER when using M-array receivers instead of one a single receiver

Investigation of turbulence effect on the free space optical link for ground-to-train communications

There is a growing demand for high mobility and ultrafast internet/data services which drives the motivation for free space optical (FSO) communications for high speed trains. Here we present an FSO link for the ground-to-train communications, which consists of optical transceivers positioned alongside the track and on the roof of the train. When the train moves at a high speed, the airwave induced turbulence degrades the FSO link performance. In this paper the effect of turbulence is experimentally investigated and compared with the case of no turbulence

Atmospheric propagation issues relevant to optical communications

Atmospheric propagation issues relevant to space-to-ground optical communications for near-earth applications are studied. Propagation effects, current optical communication activities, potential applications, and communication techniques are surveyed. It is concluded that a direct-detection space-to-ground link using redundant receiver sites and temporal encoding is likely to be employed to transmit earth-sensing satellite data to the ground some time in the future. Low-level, long-term studies of link availability, fading statistics, and turbulence climatology are recommended to support this type of application

Deep space communication and navigation study. Volume 1 - Summary

Comparison of alternative means for high data rate communication from deep space probes, and deep space navigation by orbiting spacecraf

Route diversity analyses for free-space optical wireless links within turbulent scenarios

Free-Space Optical (FSO) communications link performance is highly affected when propagating through the time-spatially variable turbulent environment. In order to improve signal reception, several mitigation techniques have been proposed and analytically investigated. This paper presents experimental results for the route diversity technique evaluations for a specific case when several diversity links intersects a common turbulent area and concurrently each passing regions with different turbulence flows