Abstract
There is a need to compensate for the power fluctuations in free space optical (FSO) communication links due to the turbulence and other atmospheric phenomena. In order to overcome atmospheric turbulence induced fades, several techniques have been proposed. These include: spatial transmitter/receiver diversity, adaptive beam forming based on the wave front phase error measurement and the setting of the opposite phase aberration on the beam by a deformable mirror, wavelength diversity, multiple-beam communication and novel modulation techniques. In this chapter, the performance of FSO systems with spatial and time diversities is presented. To illustrate the diversity techniques, only the subcarrier intensity modulation scheme will be considered. The diversity techniques outlined can however, be extended to other modulation schemes without any loss of generality. The spatial diversity analysis is based on the linear combining techniques: equal gain combining, maximum ratio combining and selection combining. Inter-symbol interference is not being considered since terrestrial FSO links are basically a line-of-sight technology with the negligible delay spread. The chapter also outlines experimental results for verification of the diversity schemes for FSO links. To ensure link availability at all weather conditions the chapter also presents measurement campaign for an outdoor FSO/radio frequency link.
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References
Hashmi, A., et al.: Analysis of optimal adaptive optics system for hybrid RF-wireless optical communication for maximum efficiency and reliability. In: Proceedings of the Emerging Technologies, 2008. ICET 2008. 4th International Conference on, pp. 62–67 (2008)
Weerackody, V., Hammons, A.R.: Wavelength correlation in free space optical communication systems. In: Proceedings of the Military Communications Conference, 2006. MILCOM 2006. pp. 1–6. IEEE (2006)
Anguita, J.A., et al.: Spatial correlation and irradiance statistics in a multiple-beam terrestrial free-space optical communication link. Appl. Opt. 46, 6561–6571 (2007)
Chatzidiamantis, N.D., et al.: Adaptive subcarrier PSK intensity modulation in free space optical systems. IEEE Trans. Commun. 59, 1368–1377 (2011)
Lee, E.J., Chan, V.W.S.: Part 1: optical communication over the clear turbulent atmospheric channel using diversity. IEEE J. Sel. Areas Commun. 22, 1896–1906 (2004)
Lee, I.E., et al.: Practical implementation and performance study of a hard-switched hybrid FSO/RF link under controlled fog environment. In: Proceedings of 9th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP), pp. 368–373 (2014)
Simon, M.K., Alouini, M.-S.: Digital Communication Over Fading Channels, 2nd edn. Wiley-Interscience, Hoboken, N.J. (2005)
Komiyama,T., et al.: Study of visible light communication system using RGB LED lights. In: Proceedings of SICE Annual Conference (SICE), 2011, pp. 1926–1928 (2011)
Mitchell, R.L.: Permanence of the log-normal distribution. J. Opt. Soc. Am. 58, 1267–1272 (1968)
Kaushal, H., et al.: Experimental study on beam wander under varying atmospheric turbulence conditions. Photonics Technol. Lett. IEEE 23, 1691–1693 (2011)
Ghassemlooy, Z., et al.: Performance analysis of ethernet/fast-ethernet free space optical communications in a controlled weak turbulence condition. J. Lightwave Technol. 30, 2188–2194 (2012)
Zvanovec, S., et al.: Route diversity analyses for free-space optical wireless links within turbulent scenarios. Opt. Express 21, 7641–7650 (2013)
Perez, J., et al.: Experimental characterization and mitigation of turbulence induced signal fades within an ad hoc FSO network. Opt. Express 22, 3208–3218 (2014)
Ghassemlooy, Z., et al.: Optical Wireless Communications : System and Channel Modelling with MATLAB. Taylor & Francis, Boca Raton, FL (2012)
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Ghassemlooy, Z., Popoola, W., Zvanovec, S. (2016). Diversity for Mitigating Channel Effects. In: Uysal, M., Capsoni, C., Ghassemlooy, Z., Boucouvalas, A., Udvary, E. (eds) Optical Wireless Communications. Signals and Communication Technology. Springer, Cham. https://doi.org/10.1007/978-3-319-30201-0_19
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DOI: https://doi.org/10.1007/978-3-319-30201-0_19
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