A linear chained approach for service invocation in IP Multimedia Subsystem

IP Multimedia Subsystem (IMS) is considered to provide multimedia services to users through an IP-based control plane. The current IMS service invocation mechanism, however, requires the Serving-Call Session Control Function (S-CSCF) invokes each Application Server (AS) sequentially to perform service subscription profile, which results in the heavy load of the S-CSCF and the long session set-up delay. To solve this issue, this paper proposes a linear chained service invocation mechanism to invoke each AS consecutively. By checking all the initial Filter Criteria (iFC) one-time and adding the addresses of all involved ASs to the “Route” header, this new approach enables multiple services to be invoked as a linear chain during a session. We model the service invocation mechanisms through Jackson networks, which are validated through simulations. The analytic results verify that the linear chained service invocation mechanism can effectively reduce session set-up delay of the service layer and decrease the load level of the S-CSCF.

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► We present a linear chained service invocation for IMS to invoke multiple services consecutively in a session.
► The new approach checks all the iFCs one-time and adds the addresses of all involved ASs to the “Route” header.
► The linear chained service invocation algorithm is proposed.
► We model the service invocation mechanisms through Jackson networks.
► The session set-up delay and the load level of the S-CSCF are improved.