Performance Analysis of Different Modulation Techniques for Free-Space Optical Communication System
Abstract: Free space optical
system is a hot topic, which has gaining more and more attention. But, when the
signal transmitted in the channel, the performance could be severely degraded
due to the atmosphere turbulent. The purpose of this paper is to find a most
suitable modulation method for FSO system under FSO channel. The performance of
power efficiencies, bandwidth efficiency, BER and SNR for the four modulation
schemes have studied and compared in this paper include On-Off keying (OOK),
Binary Phase Shift Keying (BPSK), Differential Phase Shift Keying (DPSK) and
Quadrature Phase Shift Keying (QPSK) without atmospheric turbulence. Numerical
experiments show that BPSK and QPSK schemes are better compared to other
schemes in BER performance and power requirements. When take intensity
scintillation under Gamma-Gamma turbulence channel into consideration and the
average BER is derived with Meijer-G function, BER performances of BPSK and
QPSK scheme approximate the same. Compared with BPSK, BER performance for QPSK
is 3dB lower. From the simulation results, modulation for BPSK is robust resist
turbulence. As a result, BPSK scheme is suitable for free-space optical
communication system.
Keywords: free-space optical
communication, bit error rate, modulation scheme, signal–noise rate, gamma-gamma
turbulence channel
Author: Huiying Zhang, Hongzuo
Li ,Xiao Dongya, Cai Chao
Journal Code: jptkomputergg150148
