Performance enhancement of a digital pulse position modulation for FSO communication systems impaired by interchannel crosstalk, pointing error, and ASE noise

Abstract

<title>Abstract</title> The performance evaluation and enhancement of a digital pulse-position modulation (DPPM) and on-off keying (OOK) modulation for the free-space optical (FSO) communication systems are investigated in this paper. We develop a moment generating function for the post-detection noise processes which takes into account a comprehensive set of the key amplifier and receiver parameters, including gain and amplified spontaneous emission (ASE) noise characteristics of FSO communications. The impact of atmospheric turbulence, inter-channel crosstalk, scintillation, pointing error, and ASE noise has been taken into account. To reduce the turbulence-induced scintillation and optical power penalty, the use of an aperture averaging has been proposed in this paper. Such a system, which could provide a power-efficient, a low cost, excessive flexibility and reliable or considered a massive solution in the bandwidth provision for future access networks, and together for higher data rate. Numerical results show the superiority of DPPM with improved receiver sensitivity at a bit-error-rate of 10^-12 about 9 dB for a coding level of 5 and FSO link length of 2500 m more than an equivalent OOK non-return-to-zero approach.