Maximizing Throughput in Zero-Buffer Tandem Lines with Constrained Flexible Servers

For tandem queues with no buffer spaces and both dedicated and flexible servers, we study how flexible servers should be assigned to maximize the throughput. We focus on systems in which flexible servers are constrained to serve at specific stations. With three stations and one or two constrained flexible servers, we completely characterize the optimal policies and compare throughput improvement with systems in which flexible servers are not constrained. Using numerical experiments, we discuss the impact of constrained flexibility on performance and dimensioning of systems.