Abstract
Ultraviolet communication (UVC) is emerging as an attractive alternative to the existing optical wireless communication (OWC) technologies. UVC experiences negligible noise on the earth's surface, and also has the ability to operate in non-line-of-sight (NLOS) mode, thereby making it a perfect choice for outdoor communication. However, due to strong interaction of ultraviolet waves with atmospheric particles, it suffers from a very high path loss and turbulence-induced fading, which limits UVC system's performance. We consider a decode-and-forward based cooperative relaying technique to improve the performance of NLOS UVC system, and to extend its communication range. We consider the practical case of imperfect channel state information at the receiver and derive outage probability of the system. We also consider impact of elevation angles, receiver field-of-view (FOV), and turbulence strength on the system performance. We compute the relative diversity order of the system and demonstrate its convergence through asymptotic analysis. Next, we obtain the novel expression of probability density function of the end-to-end instantaneous signal-to-noise-ratio. We use single subcarrier intensity modulation employing quadrature amplitude modulation (QAM) and derive the novel generalized analytical expressions for rectangular QAM, cross QAM, and futuristic hexagonal QAM schemes. We carry out a detailed performance study considering different system configurations and several interesting insights are highlighted, which reinforces UVC as a futuristic OWC technology. Correctness of the derived analytical expressions is confirmed using Monte-Carlo simulations.
Highlights
U LTRAVIOLET communication (UVC) is attracting renewed research attention due to advancement in solid-state technologies and myriad applications [1] in the non-line-of-sight (NLOS) communication systems
NLOS UVC is mainly useful in scenarios where line-of-sight (LOS) is not possible to achieve, RF communication is prohibited, and/or security is of paramount importance
The channel state information (CSI) is assumed to be perfectly known at the Rx, which is impossible to achieve in practical systems [16], [17]
Summary
U LTRAVIOLET communication (UVC) is attracting renewed research attention due to advancement in solid-state technologies and myriad applications [1] in the non-line-of-sight (NLOS) communication systems. In [14], authors considered a parallel dual-hop AF-relayed NLOS UVC system, and evaluated the lower-bound on the outage probability and ASER for higher order modulation schemes In all these studies, the CSI is assumed to be perfectly known at the Rx, which is impossible to achieve in practical systems [16], [17]. In [19], authors evaluated the performance of a dual-hop variable-gain AF relayed RF communication system for Nakagami-m fading channel and studied the impact of imperfect CSI on the ASER performance of the system for a variety of higher order QAM schemes. To the best of authors’ knowledge, the ASER analysis of higher-order modulation schemes for DF based multiple-relayed cooperative NLOS UVC system considering imperfect CSI is not studied in the literature.
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