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Average channel capacity vs. aperture diameter

Effect of aperture averaging and spatial diversity on capacity of optical wireless communication systems over lognormal channels

Rahul Kaushik, Vineet Khandelwal, Roop Chand Jain


In this paper average channel capacity of optical wireless communication system with aperture averaging and diversity reception over lognormal channels is evaluated using a simple approximate closed form expression. The qualitative improvement in channel capacity is compared and investigated for various turbulence mitigation techniques: namely aperture averaging, diversity techniques such as maximal ratio combining and equal gain combining. Based on our study it has been found that aperture averaging gives reasonably improved performance as compared to both types of diversity reception beyond certain turbulence strength. However, irrespective of turbulence strength, substantial improvement in capacity may be achieved with array of direct detection receivers. Results obtained using the proposed expressions are in excellent agreement with those based on Monte Carlo simulations.


optical wireless communication; average channel capacity; aperture averaging; diversity reception; lognormal distribution

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KHALIGHI, MOHAMMAD A.; UYSAL, MURAT. Survey on free space optical communication: A communication theory perspective. IEEE Commun. Surveys Tutorials, v.16, n.4, p.2231-2258, 2014. doi:

ZHU, XIAOMING; KAHN, J.M. Free-space optical communication through atmospheric turbulence channels. IEEE Trans. Commun., v.50, n.8, p.1293-1300, 2002. doi:

ANDREWS, LARRY C.; PHILLIPS, RONALD L. Laser Beam Propagation through Random Media. SPIE Press, 1998, ISBN: 9780819459480.

MAJUMDAR, ARUN K. Advanced Free Space Optics (FSO): A Systems Approach. New York : Springer-Verlag, 2015, ISBN: 9781493909179, DOI:

CHURNSIDE, JAMES H. Aperture averaging of optical scintillations in the turbulent atmosphere. Appl. Optics, v.30, n.15, p.1982-1994, 1991. doi:

HOMSTAD, GERALD E.; STROHBEHN, JOHN W.; BERGER, ROGER H.; HENEGHAN, J.M. Aperture-averaging effects for weak scintillations. JOSA A, v.64, n.2, p.162-165, 1974. doi:

NAVIDPOUR, S. MOHAMMAD; UYSAL, MURAL; KAVEHRAD, MOHSEN. BER performance of free-space optical transmission with spatial diversity. IEEE Trans. Wireless Commun., v.6, n.8, p.2813-2819, 2007. doi:

ANGUITA, JAIME A.; DJORDJEVIC, IVAN B.; NEIFELD, MARK A.; VASIC, BANE V. Shannon capacities and error-correction codes for optical atmospheric turbulent channels. J. Optical Networking, v.4, n.9, p.586-601, 2005. doi:

NISTAZAKIS, HECTOR E.; KARAGIANNI, EVANGELIA A.; TSIGOPOULOS, ANDREAS D.; FAFALIOS, MICHAEL E.; TOMBRAS, GEORGE S. Average capacity of optical wireless communication systems over atmospheric turbulence channels. J. Lightwave Technol., v.27, n.8, p.974-979, 2009. doi:

HAAS, S.M.; SHAPIRO, J.H. Capacity of wireless optical communications. IEEE J. Sel. Areas Commun., v.21, n.8, p.1346-1357, 2003. doi:

KHALIGHI, MOHAMMAD-ALI; SCHWARTZ, NOAH; AITAMER, NAZIHA; BOURENNANE, SALAH. Fading reduction by aperture averaging and spatial diversity in optical wireless systems. J. Optical Commun. Networking, v.1, n.6, p.580-593, 2009. doi:

LEE, E.J.; CHAN, V.W.S. Part 1: Optical communication over the clear turbulent atmospheric channel using diversity. J. Sel. Areas Commun., v.22, n.9, p.1896-1906, 2004. doi:

IBRAHIM, M.M.; IBRAHIM, A.M. Performance analysis of optical receivers with space diversity reception. IEE Proc. Commun., v.143, n.6, p.369-372, 1996. doi:

ABAZA, MOHAMED; MESLEH, RAED; MANSOUR, ALI; AGGOUNE, EL-HADI M. Diversity techniques for a free-space optical communication system in correlated log-normal channels. Opt. Eng., v.53, n.1, p.016102, 2014. doi:

POPOOLA, W.O.; GHASSEMLOOY, Z.; ALLEN, J.I.H.; LEITGEB, E.; GAO, S. Free-space optical communication employing subcarrier modulation and spatial diversity in atmospheric turbulence channel. IET Optoelectronics, v.2, n.1, p.16-23, 2008. doi:

GOLDSMITH, ANDREA. Wireless Communication. Cambridge University Press, 2005, ISBN: 9780521837163.

ROSENBLUETH, EMILIO. Point estimates for probability moments. Proc. NAS, v.72, n.10, p.3812-3814, 1975. doi:

KARMESHU; KHANDELWAL, VINEET. On the applicability of average channel capacity in log-normal fading environment. Wireless Personal Commun., v.68, n.4, p.1393-1402, 2013. doi:

HOLTZMAN, J.M. A simple, accurate method to calculate spread-spectrum multiple-access error probabilities. IEEE Trans. Commun., v.40, n.3, p.461-464, 1992. doi:

LAOURINE, A.; STEPHENNE, A.; AFFES, S. Estimating the ergodic capacity of log-normal channels. IEEE Commun. Lett., v.11, n.7, p.568-570, 2007. doi:

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