Approximations and bounds for the variance of steady-state waiting times in a GI/G/1 queue

The focus of this paper is on developing bounds for the variance of steady-state waiting times in a GI/G/1 queues in terms of the first three moments of the interarrival and service time distributions. A review of the existing bounds and approximations is provided, and new bounds are derived. Numerical experience reveals that the bounds complement existing approximations in providing refinements that increase the accuracy of those approximations, especially at high traffic intensities.