Conference Paper

Hybrid Free-Space Optical and Radio-Frequency Communications: Outage Analysis

Inst. for Telecommun. Res., Univ. of South Australia, Mawson Lakes, SA, Australia
DOI: 10.1109/ISIT.2010.5513382 Conference: Information Theory Proceedings (ISIT), 2010 IEEE International Symposium on
Source: IEEE Xplore

ABSTRACT We study hybrid free-space optical (FSO) and radio-frequency (RF) communications, whereby information is conveyed simultaneously using both optical and RF carriers. We consider the case where both carriers experience scintillation, which is a slow fading process compared to typical data rates. A parallel block-fading channel model is proposed, that incorporates differences in signalling rates, power scaling and scintillation models between the two carriers. Under this framework, we study the outage probability in the large signal-to-noise ratio (SNR) regime. First we consider the case when only the receiver has perfect channel state information (CSIR case) and obtain the SNR exponent for general scintillation distributions. Then we consider the case when perfect CSI is known at both the receiver and transmitter, and derive the optimal power allocation strategy that minimises the outage probability subject to peak and average power constraints. The optimal solution involves non-convex optimisation, which is intractable in practical systems. We therefore propose a suboptimal algorithm that achieves the same diversity as the optimal one and provides significant power savings (on the order of tens of dBs) over uniform allocation.

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    ABSTRACT: This poster presents a report on experimental set up and results for a hybrid free space optics (FSO)/radio frequency (RF) dual purpose antenna for outdoor applications. The basic design of the antenna is discussed and we present two sets of early experimental results for the signal to noise ratio (SNR) and the Q-factor for the RF and FSO simplex link at the far-field distance of RF antenna, respectively. Over a link span of 15 m the measured SNR and the Q-factor are 45.68 dB and 15.69, respectively, demonstrating the functioning transmission capability of the hybrid FSO/RF link employing the proposed antenna.
    Proceeding of the Northumbria Research Conference, Newcastle, UK; 05/2014

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