Diffusion Approximation Model of Multiserver Stations with Losses

The article presents a diffusion approximation model of a G/G/N/N station – N parallel servers without queueing. Diffusion approximation allows us to include in queueing models fairly general assumptions. First of all it gives us a tool to consider in a natural way transient states of queues, which is very rare in classical queueing models. Then we may consider input streams with general interarrival time distributions and servers with general service time distributions. Single server models may be easily incorporated into a network of queues. Here, we apply the diffusion approximation formalism to study transient behaviour of G/G/N/N station and use it to construct a model of a typical call centre and to study the sliding window mechanism, a popular Call Admission Control (CAC) algorithm.