Open AccessEfficient differential signalling with reduced background radiation for multiple aperture FSO communication systems
Author(s) -
Karimi Mohammad,
Sadough Seyed Mohammad Sajad,
Torabi Mohammad
Publication year - 2020
Publication title -
iet communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.355
H-Index - 62
eISSN - 1751-8636
pISSN - 1751-8628
DOI - 10.1049/iet-com.2019.0626
Subject(s) - bit error rate , weighting , keying , signal to noise ratio (imaging) , computer science , modulation (music) , algorithm , aperture (computer memory) , mathematics , electronic engineering , channel (broadcasting) , telecommunications , physics , acoustics , engineering
The main objective of this study consists in reducing the correlated background radiations along with minimising the bit error rate (BER) for a multiple aperture 2 × 1 free‐space optical (FSO) communication system based on differential signalling scheme. Instead of performing the conventional equal gain combining (EGC) of the two wavelengths, here, the authors propose to efficiently combine them at the receiver by using non‐equal channel‐dependent weighting factors. To this aim, they first derive the analytic expression of the BER of the considered system, which is necessary for optimising the background radiations. Second, by considering ON–OFF keying modulation, they optimise the decision threshold and the weighting factors of the two wavelength by minimising the BER. The performance merit of the proposed scheme is contrasted to the zero threshold scheme and to the EGC scheme in terms of the average BER, the average signal‐to‐noise ratio (SNR) and the background rejection at the receiver. They show that the proposed scheme can improve the SNR up to 17 dB, based on the correlation coefficient of the background radiations at two wavelengths. Moreover, simulation results confirm the superiority of the proposed scheme in terms of achievable BER compared to the aforementioned conventional methods.