Quality of Service Issues in Hybrid Fiber Coax Networks

The IEEE working group is currently standardizing a new media access control MAC protocol for the emerging Hybrid Fiber Coax HFC networks Crucial for the success of will be its ability to support Quality of Service QoS for delay and throughput sensitive applications such as multimedia Two methods are presented in this thesis to provide QoS e cient interoperability with Asynchronous Transfer Mode ATM services and the design and simulation of a novel priority scheme HFC networks must support higher layer tra c services namely ATM Constant Bit Rate CBR Variable Bit Rate VBR and Available Bit Rate ABR tra c classes This rst part of this thesis investigates the inter operation of the MAC pro tocol as de ned by with ABR transmissions An important nding of this study is that multiple users contending for bandwidth on the upstream channel in the HFC network may interfere with the feedback congestion control mechanisms of ABR tra c control This interference can result in unfairness between ABR sources and decreased utilization of the upstream HFC channel As a solution to the prob lem we propose a scheme whereby the headend station of the HFC network returns congestion information contained in resource management RM cells to the ABR sources The proposed mechanism can be incorporated into the ABR rate control