Table of Contents
ISRN Communications and Networking
Volume 2011, Article ID 701670, 14 pages
http://dx.doi.org/10.5402/2011/701670
Research Article

Turbo-Coded MC-CDMA Communication Link over Strong Turbulence Fading Limited FSO Channel with Receiver Space Diversity

Electrical and Electronic Engineering, Bangladesh University of Engineering and Technology, Dhaka 1000, Bangladesh

Received 6 April 2011; Accepted 18 May 2011

Academic Editor: C. Carbonelli

Copyright © 2011 MD. Zoheb Hassan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper demonstrates an analytical approach on the bit error rate (BER) performance evaluation of a multi- carrier code division multiple access (MC-CDMA) communication link operating over terrestrial free space optical (FSO) channel considering effect of atmospheric turbulence The turbulence induced intensity fading is statistically modeled by Gamma-Gamma PDF (probability density function). Bit error rate performance improvement is proposed using photo detector spatial diversity with Equal Gain Combining (EGC) and Turbo Coding. Analysis is carried out with different bandwidth efficient phase shift keying (PSK) based sub-carrier intensity modulation (SIM) with direct detection. Numerical simulation results of proposed analytical model indicate that, sub-carrier intensity modulation scheme; number of receiver photo detectors, turbo coding parameter and link length should be optimally engineered for ensuring system reliability. It can be inferred from the simulation that, a reliable communication link ( 1 0 1 0  BER) can be established over a link length of 4 Km in strong turbulence fading condition using an array of 4 PIN photo detectors, 8-ary PSK based sub-carrier intensity modulation scheme and appropriate turbo coding parameter with an average 10.2 dB CINR (Carrier to Interference and Noise Ratio) requirement per photo detector. Besides, more than 130 dB average CINR gain is also confirmed from BPSK modulated, un-coded SISO (single input-single output) system for maintaining targeted BER ( 1 0 1 0 ) in presence of strong turbulence fading.