Investigations on delay and CDV in an ATM-based optical access network

Modern network technology simplifies considerably the provision of services by providing the user with a unique interface to a single integrated services network which will handle all the user needs. This, however, introduces a very high provision cost and hence cannot be used to connect small and residential users. An access network overcomes this problem, allowing a relative large number of small scale users to share resources such that traffic is concentrated and a single point of entry to the high speed network can be used in a more economical manner. This paper presents the result of an investigation carried out to explore some of the issues concerning a real optical access network which supports ATM and assumes a passive optical network with a tree topology as its distribution network. The paper describes all the important features of the network and reveals the results of the experiments that were carried out on a demonstrator. These experiments were performed using a traffic generator to multiplex heterogeneous mixes of traffic and study the performance of the access network under different load conditions. This study is compared with simulation results and reveal that the implemented access network operates as it was designed to do. Furthermore, the slot format used, which assumes only a small overhead, is seen to be sufficient for APON technology. Finally, the results show that the medium access control protocol, which was specially designed for the demonstrator, distributes the available data rate over all the termination points in a flexible, efficient and robust way.