Hardware implementation of multimedia driven HFC MAC protocol

Tree-shaped topologies present attractive cost advantages for broadband access networks by allowing many customers to share the expensive head-end equipment and the feeder section and provide a graceful upgrade path towards the photoionization of the local loop. In addition they offer reuse of the copper last drops to the customer at least during the crucial introductory phase and probably for many years to come. Typical examples are hybrid fiber coaxial (HFC) and passive optical network (PON) systems. The TDMA multiplexing of traffic entering such a system is governed by the MAC protocol, which arbitrates the allocation of bandwidth to the shared feeder. At the same time the need to integrate telecom services presenting different quality requirements with plain best effort services over the same infrastructure brings new issues to the design of such an access mechanism. The MAC protocol as the only arbiter of the upstream bandwidth directly affects the QoS provided to each upstream traffic flow and must meet several constraints. Such constraints include the adequate speed of operation exploiting in the highest degree the speed of H/W implementation, flexibility to support efficiently the largest number of services and applications offering an adequate number of QoS classes and independence of higher layers, protocols and future extensions to traffic management specifications. The implementation of a MAC protocol targeting these goals in the framework of the AROMA research system is presented in this paper. We discuss the details and the implementation cost of the solutions followed and we evaluate the implemented mechanisms using computer simulation.