Heavy traffic limit for the workload plateau process in a tandem queue with identical service times

Abstract

We consider a two-node tandem queueing network in which the upstream queue is GI/GI/1 and each job reuses its upstream service requirement when moving to the downstream queue. Both servers employ the first-in-first-out policy. To investigate the evolution of workload in the second queue, we introduce and study a process M, called the plateau process, which encodes most of the information in the workload process. We focus on the case of infinite-variance service times and show that under appropriate scaling, workload in the first queue converges, and although the workload in the second queue does not converge, the plateau process does converges to a limit that is a certain function of two independent Levy processes. Using excursion theory, we compare a time changed version of the limit to a limit process derived in previous work.