A Review of the Policy-Based QoS Architecture in IMS

IMS, the core architecture of NGN, becomes more and more important in modern telecommunication network. It is the main driving force to promote the evolution of telecommunication technology to "All IP" network. However, it is a big challenge that how to provide carrier grade service on best effort IP network. To solve this problem, SDOs (Standards Development Organizations) have developed some guaranteed quality of service architectures recently. This paper reviews the policy-based QoS architecture defined by SDOs, such as IETF, 3GPP (Third Generation Partnership Project) and ETSI (European Telecommunications Standards Institute). The QoS related concepts defined by each SDO are introduced firstly, and the functional entities for QoS in the architectures are presented. The paper also analyses the mechanism which ensures the entities work efficiently. Finally, we discuss the ongoing works and future trends of the QoS issues. We believe that the solutions of IMS QoS problem will make a great impact on the communications industry.