Performance evaluation of UMTS packet voice call control

3GPP Rel.5 specifies an IP multimedia core network sub-system (IMS) adjunct to the UMTS packet switched (PS) GPRS CN bearer and Rel.6 will let UMTS provide full packet call control (CC) capabilities (e.g. security, emergency and QoS support). The packet call control capabilities employ the IETF text based call control protocol SIP (session initiation protocol). Text based protocols have the advantage that they are generally easier to develop than bit-wise presentations. However, due to their larger message sizes, delays associated with packet call control using SIP have concerned operators about the viability of such services over a UMTS air interface. This has led development of message compression techniques for more efficient use of SIP. This paper provides a brief overview of GSM, UMTS circuit switched call control, and SIP based call control as applied to UMTS and then compares and contrasts the relative performance of the call control protocols using results derived from a UMTS system simulator called the Framework for Radio Architecture Modelling (FRAM).