Using differential signalling to mitigate pointing errors effect in FSO communication link

Mansour Abadi, Mojtaba, Ghassemlooy, Zabih, Bhatnagar, Manav, Zvanovec, Stanislav, Khalighi, Mohammad-Ali and Maheri, Alireza (2016) Using differential signalling to mitigate pointing errors effect in FSO communication link. In: IEEE International Conference on Communications Workshops (ICC), 23-27 May 2016, Kuala Lumpur.

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In this paper, we investigate a differential signalling (DS) scheme to mitigate pointing errors effect in intensity-modulation/direct-detection (IM/DD) free space optical (FSO) communication systems with the non-return-to-zero on-off keying (NRZ-OOK) modulation format. The most common approach to detect a digital signal is based on comparing the received signal with an optimal threshold level. Normally, this optimal threshold level is set at the mean value of the signal in a clear channel. However, this detection threshold method is inefficient in a channel with fading effects. DS has been reported to mitigate the fluctuation of optimal detection threshold in NRZ-OOK IM/DD FSO communication systems only to combat atmospheric fading effects (e.g., fog and turbulence) and to reduce the background noise of the received signal. In this paper, we adopt the DS scheme to mitigate the optimal detection threshold level fluctuations induced by pointing errors. We also discuss the conditions in which DS cancels out the fluctuation of threshold level. The proposed technique is supported by carrying out experimental investigation of the FSO link with pointing errors. Measured results confirm that the effect of PE on the received signal was highly correlated (i.e., ρ = 0.92, where ρ is the correlation coefficient between channels) thus resulting in reduced variance value of the combined signal threshold level. We also derive an expression for bit-error-rate for the system which is supported by simulation.

Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: Optical communication, free space optics (FSO), pointing errors, threshold detection
Subjects: H600 Electronic and Electrical Engineering
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Faculties > Engineering and Environment > Mechanical and Construction Engineering
Depositing User: Becky Skoyles
Date Deposited: 11 Aug 2016 09:28
Last Modified: 12 Oct 2019 12:13

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