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Congestion in the low frequency regions of the electromagnetic spectrum and demand for support of high bandwidth applications has prompted widespread investigations into networking technologies and communications media. Traditional networking technologies such as Ethernet that are not capable of adequately supporting high bandwidth applications (e.g. videoconferencing) are being replaced by high speed, high bandwidth technologies such as Asynchronous Transfer Mode (ATM). In the communications media market, wireless systems are becoming ubiquitous due to their ease of installation and maintenance costs. In this research, the networking technology of interest is ATM. ATM used a cell switching architecture that allows seamless support for all traffic types. It is also capable of providing guaranteed quality of service to different applications. This research seeks to develop a model of an ATM system in order to simulate the processes of file manipulation of an application in an ATM network in which a reliable transmissions medium is deployed. The transmission medium under investigation is a wireless optical communication link (laser). Laser systems offer a number of advantages over microwave systems. They do not require an operating license and they potentially offer larger bandwidth. Similar to microwave systems however, the performance of the laser link is dependent on atmospheric conditions. Scattering and absorption of the signal by atmospheric/weather particles may produce power losses in the transmitted signals. Theoretical models predicting such propagation impairments are widely available for microwave systems. However, there is little information available for optical systems. In this project, a model is developed to predict the effects due to rain on an optical link. This atmospheric channel model is base on the from of the drop size distribution proposed by [Marshall and Palmer, pp.165-166] and the results for the terminal velocity of raindrops found by [Gunn-and –Kinzer, pp.243-248] Experimental tests were conducted so that comparison could be made with both theoretical models developed.
Dunne, K.: An ATM System Model and Wireless Channel Simulation. Masters Thesis. Dublin Institute of Technology, 2000.