A Theoretical Model to Calculate the Bandwidth of IMS Session Establishment

Over the last years the IP Multimedia Subsystem (IMS) has continuously gained in importance as the next generation communication network. The Session Initiation Protocol (SIP) was chosen the signaling protocol for session establishment and control in IMS. Losses caused by network or server overload would cause retransmissions and delays in the session establishment and would hence reduce the perceived service quality of the users. In order to be able to take counter measures network and service planers require detailed models that would allow them to predict such effects in advance. This paper presents a theoretical model of SIP that can be used for determining various parameters such the number of messages required for establishing a call in IMS networks when taking losses into account. The model also provides a method to calculate the bandwidth required for session establishment in IMS.