engleski

Comparative Analysis of Scheduling Algorithms for UMTS Traffic in Case of DiffServ Network Congestion

Having in mind picture of future all-IP network, as well as fixed-mobile convergence, interworking between Universal Mobile Telecommunication System (UMTS) and external networks is crucial for providing end-to-end Quality of Service (QoS). For the purpose of achieving QoS in all-IP mobile networks, particularly for broadband multimedia services, Differentiated Services (DiffServ) mechanism should be applied to UMTS technology. This paper proposes using of Low Latency Queuing (LLQ) scheduler, with the main idea of mapping voice and video telephony in two different QoS classes and virtual queues, but at the same time using Priority Queuing (PQ) within LLQ for both voice and video telephony over all other QoS classes. To proof the concept, a simulation study was performed using Network Simulator version 2 (ns-2). Evaluation results of simulation study are presented for UMTS traffic that passes through UMTS core network and overloaded external IP backbone network. Performances of LLQ scheduler are compared with other most widely used scheduling algorithms such as Weighted Fair Queuing (WFQ), Weighted Round Robin (WRR) and Priority Queuing (PQ). The main objective of simulation was to provide QoS parameters such as IP Transfer Delay (IPTD), IP Delay Variation (IPDV) and IP Loss Rate (IPLR) for conversational and streaming traffic classes below standard defined values but not to completely exhaust bandwidth for interactive and background traffic classes. The obtained results were statistically processed using Statistical Package for the Social Sciences (SPSS) version 17.0.

QoS; DiffServ; Scheduling; LLQ.

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