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 ( 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 () in presence of strong turbulence fading.
Highlights
Free space optical communication (FSO) known as wireless optical communication technique is a point to point to communication link in which two optical transceivers communicate via infrared laser light propagated through atmospheric channel
radio over fiber (RoF) technology can conveniently be replaced by radio over free pace optical (RoFSO) communication link using FSO system for transmitting RF signals excluding expensive use of optical fiber [2, 3]
The main advantage of FSO communication system is being free from license requirement, no fiber implementation cost, low power requirement, availability of cost-effective equipment, and almost the same performance of optical fiber network with a fraction of cost [4]
Summary
Free space optical communication (FSO) known as wireless optical communication technique is a point to point to communication link in which two optical transceivers communicate via infrared laser light propagated through atmospheric channel. Using spatial diversity at receiver BER performance of FSO communication link limited by γ-γ turbulence fading is evaluated in [14]. Channel coding for optical wireless link along with time diversity is proposed to alleviate the effect of turbulence fading [16]. With diversity in strong turbulence fading not less than 10−6, that BER is achieved, and it requires almost equal or greater than 30–35 dB SNR [14, 18] This BER is not satisfactory for ensuring proper data communication and at the same time, this SNR requirement is very high. In this paper an analytical approach is presented on BER performance evaluation of MC-CDMA communication link over turbulence fading limited FSO channel with receiver spatial diversity and turbo coding.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
