A high bit rate free space optics based ring topology having carrier?less nodes

A free space optics based ring topology that transmits full-duplex data to four different nodes in the is proposed. The link designed such do not require a local optical source transmit uplink data. wavelength division multiplexed signal composed of wavelengths each modulated by downlink baseband using differential phase shift keying transmitted towards nodes. At node, extracted and received pulses are remodulated on-off modulation format. Each node has rate 10 Gbps at distance 400 m from consecutive node. modelled on basis Gamma-Gamma channel model under turbulence conditions considering refractive index structure parameter values 5 × ? 15 , 13 12 2 / 3 . Bit error results obtained for both channels. Finally, power budget analysis presented demonstrate robustness weather conditions.