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

Mojtaba Mansour Abadi, Zabih Ghassemlooy, Manav Bhatnagar, Stanislav Zvanovec, Mohammad-Ali Khalighi, Alireza Maheri

Research output: Chapter in Book/Report/Conference proceedingConference contribution

10 Citations (Scopus)

Abstract

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., rho = 0.92, where rho 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.
Original languageEnglish
Title of host publication2016 IEEE International Conference on Communications Workshops (ICC 2016)
PublisherIEEE Explore
Pages145-150
Number of pages6
ISBN (Print)9781509004492
Publication statusPublished - 1 May 2016

Keywords

  • optical communications
  • free space optics (FSO)
  • pointing errors
  • threshold detection

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  • Cite this

    Abadi, M. M., Ghassemlooy, Z., Bhatnagar, M., Zvanovec, S., Khalighi, M-A., & Maheri, A. (2016). Using differential signalling to mitigate pointing errors effect in FSO communication link. In 2016 IEEE International Conference on Communications Workshops (ICC 2016) (pp. 145-150). IEEE Explore.