Fair no-unnecessary-waiting-time-FCFS allocation rule in multi-item inventory systems

The average customer waiting time is an important measure of service quality in systems in which customers may order multiple items. In this article, we introduce a new allocation discipline that not only eliminates the unnecessary waiting time of new customers by reallocating reserved items but also retains the fairness of the First-Come-First-Serve allocation rule. We develop analytic expressions for the average customer waiting time in the system with two items and unit demands under the new allocation rule, and our numerical experiments demonstrate a reduction in waiting time. We also provide an algorithm to evaluate the average customer waiting time when a system is with multiple items and batch ordering; simulation results show that the average customer waiting time of some demands can be significantly reduced up to 99.97%.