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UBC Theses and Dissertations

Quality of service support in the backbone network of the Universal Mobile Telecommunications Systems using DiffServ model Agharebparast, Farshid


The performance of the backbone bearer service of the Universal Mobile Telecommunications System (UMTS), or of its 2.5G precedent General Packet Radio Service (GPRS), has a considerable impact on the end-to-end Quality of Service (QoS) observed by a traffic flow. The purpose of this thesis is to provide a basic methodology for provisioning QoS in this backbone network by using Differentiated Services (DiffServ), which is an IP-based QoS technology. It focuses on two important issues. First, a basic plan for QoS mapping from one system to another is presented. Second, the structure of a DiffServ-based UMTS backbone router is studied which can provide the appropriate functionality of forwarding packets with PHB s equivalent to the original UMTS QoS. In particular, three major components of a DiffServ router, including the scheduler, the dropper, and the meter, have been addressed and novel algorithms have been proposed to make them suitable for a UMTS backbone router. This thesis proposes an efficient, fair scheduling and link sharing system called DDB - FFQ , which has the capability of assigning decoupled delay bounds and bandwidth allocations. This paper also studies the implementation of Random Early Detection (RED) on a shared-memory buffer and proposes new schemes that have improved packet loss ratios. The performance of a multiple node backbone network is then evaluated by using the OPNET simulation package. The results show that in terms of delay and allocated bandwidth, the routers are able to provide the PHBs considered for each traffic aggregate. They also illustrate the link sharing capability of the router in times of congestion.

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