Bandwidth Allocation Algorithm for DOCSIS Based HFC Broadband Networks

摘要

The latest tremendous growth of the Internet has opened up a vast market for high-speed broadband data services to the home. Broadband network services have created great opportunities for new multimedia applications at both home and businesses. Data over Cable Service Interface Specification (DOCSIS) is the leading standard for data over cable networks. DOCSIS is developed to support IP flows with significantly higher data rate links for high quality data, audio, video and interactive services. It is important to provide traffic scheduling mechanisms to support Quality of Service (QoS) for such applications. DOCSIS defines six upstream services for supporting per-flow QoS. Among them it uses rt-PS service for real-time VBR traffic which has burst nature. The Headend provides periodic opportunities for unicast request, namely polling, which yields higher delay and not suitable for real-time services. In this paper, a novel scheduling mechanism and bandwidth allocation algorithm has been proposed to support VBR multimedia traffic over DOCSIS. The proposed Dynamic Unsolicited Grant Service (DUGS) scheduling algorithm makes use of piggybacking request and changes the unsolicited grant size allocation dynamically. It is shown through simulation results that throughput, channel utilization and delay performance have been improved in case of DUGS, compared with current DOCSIS protocol. This algorithm can also keep fairness among connections.