Space-time response of a cloud communication channel to an optical signal
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- Gupta, H.M. Opt Quant Electron (1980) 12: 499. doi:10.1007/BF00619923
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An optical signal,an impulse in space and step in time,is incident on a plane,parallel fixed,homogeneous cloud. The incident signal is modelled as a stream of photons, each of them executing a random walk. A Monte Carlo simulation technique is applied to obtain the space-time response of the channel when an optical receiver with a specified field of view is located at a specified distance below the cloud. The response is obtained as angular, spatial and temporal dispersions. Various simulation steps are described. For thin clouds two variance reduction techniques, i.e. Russian roulette and forced collision, are used. It is shown that the bottom of the cloud tends to diffuse uniformly and the 3 dB exit beam width saturates. The rise time in this channel is found to be of the order of several nanoseconds.