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Updated: May 16, 2026
Quasi-light Storage for Optical Data Packets
Published on: February 6, 2014
Hybrid pulse position modulation and binary phase shift keying subcarrier intensity modulation for free space optics
Monire Faridzadeh1, Asghar Gholami, Zabih Ghassemlooy
1Department of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran.
Abstract:
In this paper a hybrid modulation scheme based on pulse position modulation (PPM) and binary phase shift keying subcarrier intensity modulation (BPSK-SIM) schemes for free-space optical communications is proposed. The analytical bit error rate (BER) performance is investigated in weak and saturated turbulence channels and results are verified with the simulation data. Results show that performance of PPM-BPSK-SIM is superior to BPSK-SIM in all turbulence regimes; however, it outperforms 2-PPM for the turbulence variance σ(1)(2)>0.2. PPM-BPSK-SIM offers a signal-to-noise ratio (SNR) gain of 50 dB in the saturation regime compared to BPSK at a BER of 10(-6). The SNR gain in comparison to PPM improves as the strength of the turbulence level increases.
