Parallel relay-assisted free-space optical communication using multi-pulse position modulation over the generalized turbulence channel model

• Published in: Journal of optics (New Delhi) 2022-03, Vol.51 (1), p.133-141
• Main Authors: Magidi, S., Jabeena, A.
• Format: Article
• Language: English
• Subjects: Atmospheric turbulence; Communication; Communications systems; Configurations; Free space optics; Free-space optical communication; Lasers; Nodes; Noise threshold; Optical Devices; Optics; Outages; Photonics; Physics; Physics and Astronomy; Pulse position modulation; Relay; Relaying; Research Article; Signal quality; Signal to noise ratio
• ISSN: 0972-8821; 0974-6900
• DOI: 10.1007/s12596-021-00759-y

Relays play a pivotal role in free-space optical (FSO) communication system and thus has found tremendous applications mainly to enhance the signal quality and propagation distance coverage in the presence of atmospheric turbulence. Serial relaying or parallel relaying configurations are two major configurations used. In this paper, we analyze the performance of the parallel relay-assisted FSO influenced by the generalized Malaga (M) turbulence channel. In the first instance, the data modulation at the source and each relay is signaled using the multi-pulse position modulation. Next, closed-form expressions for the outage probability have been derived and later on used for the analysis of the influence of the threshold signal to noise ratio transmitter power as well as the number of relay nodes between the source and the destination on the overall outage probability. When direct transmission between source and destination is considered, the outage probability 3.965 × 10 - 7 , 5.783 × 10 - 6 , 7.156 × 10 - 3 for weak, moderate and strong turbulence, respectively. However, when a parallel relay configuration with three paths and two hops per path is considered, the outage probability improves to 6.23 × 10 - 20 , 1.93 × 10 - 16 , 3.96 × 10 - 7 for weak, moderate and strong turbulence, respectively, for a threshold signal-to-noise ratio of 10 dB . The results revealed that the use of parallel relay nodes is a clear performance improvement option in turbulence-affected FSO communication systems.