Traffic study of ATM over passive optical networks

This paper describes the results of an investigation into the behavior of two medium access control (MAC) protocols for the provision of asynchronous transfer mode (ATM) over passive optical networks (PONs). The two paradigms of APON provision--cell-based MACs and frame-based MACs--are investigated. The protocols have been modelled using object-oriented cell-level discrete-time simulation techniques. The investigation compares the two protocols for their cell delay variation (CDV) performance in response to varying terminal peak transmission rate, traffic model and traffic load distribution asymmetry. The protocols are also examined in terms of their effect on emergent traffic shape. Computer simulation characteristics indicate that a trade-off exists between CDV and traffic shape since the frame- based MAC is superior in CDV performance and the cell-based MAC produces superior traffic shape. Also presented is a hybrid approach combining the multiple cell-allotment strategy approach of the frame-based MAC protocol with the permit-allotment strategy of the cell-based MAC protocol. Simulation results demonstrate that mean delay performance of the hybrid is superior to both standard approaches.