Abstract
IP Multimedia Subsystem (IMS) allows the use of unlicensed, non-dedicated and nondeterministic access networks for delivering IP multimedia services. Providing end-to-end Quality-of-Service (QoS) for resource demanding real-time services (e.g. real-time multimedia) over such networks is a challenging task due to varying resource availability of the network and the end-device i during a single session ii . A common solution to this problem is adapting service quality and type according to availability of system resources, which requires end-to-end monitoring and signaling of resource availability during a single session. This paper presents an extension of the IMS architecture for real-time resource availability monitoring and signaling. The novelty of the proposed extension is twofold. It takes into account uncontrolled access networks with no resource reservation on the one hand, and end devices on the other. Two system architecture components are introduced for monitoring and signaling of the real-time resource availability in both networks (e.g. bandwidth, buffer space), and end-devices (e.g. battery, CPU, memory, storage), namely a Resource Manager (RM) and a Resource Availability Server (RAS). Our solution does not require any modifications of the IMS architecture and can be implemented as a plug-in.
Highlights
Today’s smart phones and personal digital assistants (PDA) with wireless local area network (WLAN) connectivity are capable of accessing voice, video and data services outdoors over the Internet
The multimedia session between PDA's is carried over Real-time Transport Protocol (RTP) and the PDA's are Resource Availability Server (RAS) server when a call takes place
This is quite realizable in a reallife deployment of the IP Multimedia Subsystem (IMS) core network since i) all components (CSCF’s and HSS’s) of the system normally reside on different hardware nodes in a deployed IMS core, ii) using multiple instances of the same component is very common for load-balancing, and iii) the state-of-the-art processors of today are much more powerful than a 3GHz Intel Pentium 4 processor
Summary
Today’s smart phones and personal digital assistants (PDA) with wireless local area network (WLAN) connectivity are capable of accessing voice, video and data services outdoors over the Internet. It is currently envisioned that the operators must provide services to users even if they are in access networks that are completely out of their control, the need for new end-to-end QoS mechanisms. The term “endto-end” refers to the connection from the user-agent or the proxy to the server in telecom networks According to this definition, the path from one end to the other lies within the core network owned and controlled by the operator.
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