MODELING CALL HOLDING TIME DISTRIBUTIONS FOR CCS NETWORK DESIGN AND PERFORMANCE ANALYSIS

The message traffic offered to the CCS signaling network depends on and is modulated by the traffic characteristics of the circuit switched calls supported by the CCS network. Most previous analyses of CCS network engineering, performance evaluation and congestion control protocols generally assume an exponential holding time of circuit switched calls. Analysis of actual holding time distributions in conversations, facsimile and voice mail connections revealed that these distributions radically differ from the exponential distribution. Especially significant is the large proportion of very short calls in real traffic in comparison with the exponential distribution model. The diversity of calls (partial dialing, subscriber busy, no answer) and services results in a multi-component call mix, with even larger proportion of short time intervals between message-generating events. Very short call holding times can have a significant impact on the traffic stream presented to the CCS network: for calls with short holding times, the different CCS messages arrive relatively close to each other, and this manifests as burstiness in the CCS traffic stream.