A Dynamic Weighted Round Robin Call Admission (DWRR-CAC) Algorithm for Broadband Networks

In this study, a dynamic weighted round robin call admission (DWRR-CAC) scheme is proposed as an improvement to the recently proposed weighted round robin call admission (WRR-CAC) which reduces new connection blocking rate but wastes network resources due to the fixed reservation and degradation mechanisms it deploys. The DWRR-CAC algorithm solves the problem of resource wastage by deploying three mechanism: a precheck, dynamic degradation, and weight computer mechanism. First it admits all connections based on their maximum sustained traffic rate (MSTR) when the network resources are underutilized. Next, when the available resources are not sufficient to admit new connections, it deploys a pre-check mechanism to determine whether degrading existing non-UGS connections will yield sufficient bandwidth to admit the new connection or not. If the check is passed, the scheme deploys a dynamic degradation mechanism which degrades only existing non-UGS connections to admit the new connections as the non-UGS connections have adaptive QoS requirements but the UGS connections do not. The dynamic degradation mechanism ensures that only the required bandwidth is degraded. If the check fails, the connections are queued according to their traffic classes and retried after some resources are adapted from completed calls. The queued connections are admitted based on the computed WRR weight. Several simulation experiments were conducted to evaluate the performance of the DWRR-CAC against QOGCAC and WRR-CAC using a discrete event simulator. The results show that DWRR-CAC out performs the benchmark schemes in terms of call blocking rate, average and per-flow throughput.