Staffing of time-varying queues to achieve time-stable performance

• 成果类型: Article
• 署名作者: Feldman, Zohar; Mandelbaum, Avishai; Massey, William A.; Whitt, Ward
• 署名单位: Technion Israel Institute of Technology; Princeton University; Columbia University
• 刊物名称: MANAGEMENT SCIENCE
• ISSN/ISSBN: 0025-1909
• DOI: 10.1287/mnsc.1070.0821
• 发表日期: 2008
• 页码: 324-338
• 关键词: contact centers; Call centers; staffing; nonstationary queues; queues with time-dependent arrival rates; many-server queues; capacity planning; queues with abandonment; time-varying Erlang models

摘要

This paper develops methods to determine appropriate staffing levels in call centers and other many-server queueing systems with time-varying arrival rates. The goal is to achieve targeted time-stable performance, even in the presence of significant time variation in the arrival rates. The main contribution is a flexible simulation-based iterative-staffing algorithm (ISA) for the M-t/G/s(t) + G model-with nonhomogeneous Poisson arrival process (the M,) and customer abandonment (the +G). For Markovian M-t/M/s(t) + M special cases, the ISA is shown to converge. For that M-t/M/s(t) + M model; simulation experiments show that the ISA yields time-stable delay probabilities across a wide range of target delay probabilities. With ISA, other performance measures-such as agent utilizations, abandonment probabilities, and average waiting times-are stable as well. The ISA staffing and performance agree closely with the modified-offered-load. approximation, which was previously shown to be an effective staffing algorithm without customer abandonment. Although the ISA algorithm so far has only been extensively tested for M-t/M/s(t) + M models, it can be applied much more generally-to M-t/G/s(t) + G models and beyond.