1. De-Registration Based S-CSCF Load Balancing

1. De-Registration Based S-CSCF Load Balancing - This full...

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Abstract IP Multimedia Subsystem (IMS) provides a common control layer over which the services can be easily accessed by fixed and mobile users. In order to guarantee performance to both service providers and end service subscribers, careful management and maintenance within the control layer must be fulfilled. In this paper, we propose a solution that utilizes a controlling entity to track the utilization of hotspot Session Initiation Protocol (SIP) server (i.e., S-CSCF) and to initiate de-registration procedure so that a sufficient number of subscribers at the overloaded S-CSCF are re-associated with the other S-CSCF(s) for subsequent session services. The proposed solution redistributes and smoothes the future traffic load over individual S-CSCF in an automatic manner. The goodness of the proposal is assessed through simulations using OPNET. Index Terms — IP Multimedia Subsystem, SIP Server, Load Balancing, Autonomic Management I. INTRODUCTION The IP Multimedia Subsystem (IMS), as the next-generation IP-based service framework, provides access to multimedia applications by wireless and wired terminals to achieve Fixed-Mobile Convergence (FMC). The framework was originally proposed by 3GPP to support GPRS network, and has been then actively updated and developed [1]. The key merit of the framework is its decoupling of the service and control logic. This decoupling enables service providers to develop and introduce new service features in a more plug-and-play manner without the need to consider underlying control logic. The framework also enables network operators to manage the control functions in a common control layer more consistently [2]. The control layer contains complete subscriber information and provides service session control and management. Because the control layer is critical in providing the right quality of experience to the end user, our research focus in this paper is to explore how the layer can improve service performance. Figure 1 illustrates a simplified architecture of the IMS control layer. The main elements of the layer are: the Home Subscriber Servers (HSS) and different purposed Call/Session Control Function (CSCF) servers. The control layer connects to the Application Servers (AS) in the service layer and to the User Equipment (UE) through transport layer [3]. The Proxy-CSCF (P-CSCF) acts as the contact point with UE for core network service access; Interrogating-CSCF (I-CSCF) This work was supported in part by NSERC Grant CRDPJ 354729-07 and NSERC Grant RGP 261469-2003. provides routing for the signaling messages; and Serving-CSCF (S-CSCF) takes the full responsibility in UE registration, session control, and service routing with AS. Indeed, the S-CSCF unit has to virtually handle all major tasks in the control layer and it is where the majority of signaling traffic has to be processed.
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1. De-Registration Based S-CSCF Load Balancing - This full...

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