A case study in simulating PCS networks using time warp

There has been rapid growth in the demand for mobile communications over the past few years. This has led to intensive research and development efforts for complex PCS (personal communication service) networks. Capacity planning and performance modeling is necessary to maintain a high quality of service to the mobile subscriber while minimizing cost to the PCS provider. The need for flexible analysis tools and the high computational requirements of large PCS network simulations make it an excellent candidate for parallel simulation. Here, we describe our experiences in developing two PCS simulation models on a general purpose distributed simulation platform based on the Time Warp mechanism. These models utilize two widely used approaches to simulating PCS networks: (i) the call-initiated and (ii) the portable-initiated models. We discuss design decisions that were made in mapping these models to the Time Warp executive, and characterize the workloads resulting from these models in terms of factors such as communication locality and computation granularity. We then present performance measurements for their execution on a network of workstations. These measurements indicate that the call-initiated model generally outperforms the portable initiated model, but is not able to capture phenomenon such as the "busy line" effect. Moreover, these studies indicate that the high locality in large-scale PCS network simulations make them well-suited for execution on general purpose parallel and distributed simulation platforms.<
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