چكيده به لاتين
Today session initiation protocol (SIP) is widely used as a standard protocol for multimedia applications and it is considered as a signaling protocol for IP multimedia subsystem (IMS). IMS is introduced by 3GPP as signaling foundation in next generation networks (NGN). Despite having the features such as: text based, IP based, independent of the data transmission, support for mobility and end-to-end, the SIP protocol has not suitable mechanism to deal with overload. This challenge will cause a wide range of NGN users facing with a sharp drop in quality of service.
Since a distributed SIP network is a complex system composed of subsystems interacting with each other, multi-agent system (MAS) is appropriate method to solve the overload in the SIP networks with each scale. An approach to reduce the complexity of such systems is to use organization based on MAS. In this thesis, an organization used to model a large SIP network is called holonic. Each holon covers a geographical area of the SIP network in the first level. In the second level, holons control the first level holon and so on. Hence, hierarchical structure is formed for holons. The overload control is achieved by communication and the knowledge exchange between the holons. Holons implement an end-to-end window-based, loss-based and learning-based method. These methods offer an appropriate size to edge servers to control load from the beginning of the network and prevent network overload. The simulation results are compared with known methods to confirm improved throughput, reduced call setup delay, rapid response to change and fairness.
