Free Space Optics (FSO) is the technology where transmission occurs through optical waveform that contains data transformed at the transmitter from electrical signal. Since the transmission medium of FSO is atmosphere, atmospheric scattering is the major cause for interruption of FSO link. Non return zero (NRZ) modulation is the dominant modulation scheme employed in commercial terrestrial Free Space Optic (FSO) communication systems. This research are required to investigate three viable modulation techniques; non-chirped NRZ, chirped NRZ, and alternate-chirped NRZ at 10 Gb/s and 40 Gb/s data rate. The 1550 nm of continuous wave (CW) laser is modulated with three different modulation formats over 1 km of FSO channel. The signal is propagated at different attenuation value based on Malaysia weather conditions. In this paper we have successfully compared the three modulation techniques in FSO system due to the Malaysia weather and the performance is accessed at bit error rate (BER) of 1x10-9. The presented simulation of these three modulation shows that alternate-chirped NRZ has slightly better performance compared to the non-chirped NRZ and chirped NRZ modulation format at clear weather, haze, light rain, medium rain and heavy rain. We believe that, this system is an alternative for the future optical wireless network that has a potential to be installed in the urban and sub-urban area.
|Number of pages
|ARPN Journal of Engineering and Applied Sciences
|Published - 2015
- Free space optic
- Non return zero