Rate-based headend request control protocol for MAN

The paper presents a new MAC protocol, rate-based headend request control (RHRC), for dual unidirectional bus networks, which overcomes the unfairness of DQDB by allowing each station to generate multiple requests while retaining most of the positive features of DQDB, including 100% bandwidth utilization and low access delay at very low load. In addition, the protocol has two attractive features. Firstly, the transmission mechanism controlling station access to the data channel is able to provide approximately equal opportunity to messages so that they experience almost the same average delay independent of their physical locations and the traffic distribution. Secondly, the bandwidth allocation mechanism can achieve fair bandwidth sharing among stations when the network is overloaded, while maintaining fairness in terms of message delay amongst the underloaded stations. This mechanism also results in a shorter transient period than the bandwidth balancing mechanism of DQDB. Simulation results are included and comparisons are made with DQDB