Radio overfree space optics (Ro-FSO) is a modern communication technique that promises a development future. In this paper, WDM Ro-FSO communication system has designed (10 Gbps×8λ) for transmissions 80 Gbps data rate via the largest possible distance under clear air, heavy rain, and heavy fog atmosphere conditions of FSO link, with test the best wavelengths performance of (193.1 to 93.8) THz that each one (wavelength) carry 10 Gbps by employ BER analyzer at receiver channels. The electric signals produced by phase shift keying (PSK) modulation technique modulated the information (10 Gbps) on RF signal (20 GHz). The results of transporting 80 Gbps were 5 km under clear air weather condition, 1.2 km under heavy rain, and 0.2 km under heavy fog condition. Finally, the different wavelengths that carry high-value data rate are tested by measurement of the BER and Q factor for each received channel, and the theoretical model of PSK modulation is analyzed.

In this paper, we propose a communication system for an underwater environment based on the LED. Different modulation techniques examined under pure and coastal water. A BER analyzed to assess the system with a different situation. The simulation results indicate that a LED can be operated with a good received information quality under pure sea water. For coastal water, the results can be supported by increasing the power of the LED. On the other hand, 32-PPM scheme considers a good suitable modulation technique to operate with light LED.

Free-space optical (FSO) communication consider license free, high data rate, wide bandwidth and cost-effective. Multi-input Multi-output (MIMO) systems can be employed to reduce the attenuation by heavy fog and improve FSO channel capacity. In this paper a single-input single-output and multi–input multi-output examined to investigate the performance of these systems under heavy fog. A comparison is made in terms of received optical power, signal to noise ratio, and bit error rate (BER) using OptiSystem version 7.0. The signal reaches to link up to 1.7km, 1.55km, 1.5km, and 1.4km for 4Tx/4Rx, 3Tx/3Rx, 2Tx/2Rx, 1Tx/1Rxrespectively. The results showed that the quality of received power is enhancement by using up to four beams.