Abstract-Mobile radio systems for public safety and agencies engaged in emergency response and disaster recovery operations must support multicast voice traffic. In this paper, we analyze the distribution of call inter-arrival and call holding times for multicast voice (talk group) traffic on a transmission trunked mobile radio system. In such systems, the channel is held only while a user is making a call (while the push-to-talk key is pressed and the radio is transmitting). We find that the call inter-arrival time distributions are exponential and exhibit tendency toward long-range dependence. The call holding times best fit lognormal distributions and are not correlated. A potentially important implication of these findings is that performance estimation methods that assume memoryless Markov arrival and departure processes may not be viable approaches.Index Terms-Mobile communications, radio systems, public safety networks, analysis of voice traffic.

No abstract

In this article, the authors describe simulation and performance evaluation of a deployed radio communication network operated by a public safety agency. The network consists of a central site and multiple cells.Each cell has a finite number of available radio channels. The network is circuit-switched. Hence, the system utilization is a time and space distribution of the number of concurrent calls. To determine the traffic load variations, the authors analyze activity data from sample weeks in 2002 and 2003. They simulate the network by using the OPNET simulation tool and a newly developed network simulator named WarnSim. Simulation models are based on the collected activity data and are used to evaluate the utilization of system resources and to locate network bottlenecks.

No abstract