A new $1/(1-ρ)$-scaling bound for multiserver queues via a leave-one-out technique

Fuente: arXiv
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Main Author: Hong, Yige
Format: Preprint
Published: 2025
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author Hong, Yige
author_facet Hong, Yige
contents Bounding the queue length in a multiserver queue is a central challenge in queueing theory. Even for the classical $G/G/n$ queue with homogeneous servers, it is highly non-trivial to derive a simple and accurate bound for the steady-state queue length that holds for all problem parameters. A recent breakthrough by Li and Goldberg (2025) establishes a universal bound of order $O(1/(1-ρ))$ that holds for any load $ρ< 1$ and any number of servers $n$. This order is tight in many well-known scaling regimes, including classical heavy-traffic, Halfin-Whitt and Nondegenerate-Slowdown. However, their bounds entail large constant factors and a highly intricate proof, suggesting room for further improvement. In this paper, we present a new universal bound of order $O(1/(1-ρ))$ for the $G/G/n$ queue. Our bound, while restricted to the light-tailed case and the first moment of the queue length, has a more interpretable and often tighter leading constant. Our proof is relatively simple, utilizing a modified $G/G/n$ queue, the stationarity of a quadratic test function, and a novel leave-one-out coupling technique. Finally, we also extend our method to $G/G/n$ queues with fully heterogeneous service-time distributions.
format Preprint
id arxiv_https___arxiv_org_abs_2510_11015
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A new $1/(1-ρ)$-scaling bound for multiserver queues via a leave-one-out technique
Hong, Yige
Probability
Performance
60K25 (Primary) 68M20, 90B22 (Secondary)
C.4; G.3; I.6
Bounding the queue length in a multiserver queue is a central challenge in queueing theory. Even for the classical $G/G/n$ queue with homogeneous servers, it is highly non-trivial to derive a simple and accurate bound for the steady-state queue length that holds for all problem parameters. A recent breakthrough by Li and Goldberg (2025) establishes a universal bound of order $O(1/(1-ρ))$ that holds for any load $ρ< 1$ and any number of servers $n$. This order is tight in many well-known scaling regimes, including classical heavy-traffic, Halfin-Whitt and Nondegenerate-Slowdown. However, their bounds entail large constant factors and a highly intricate proof, suggesting room for further improvement. In this paper, we present a new universal bound of order $O(1/(1-ρ))$ for the $G/G/n$ queue. Our bound, while restricted to the light-tailed case and the first moment of the queue length, has a more interpretable and often tighter leading constant. Our proof is relatively simple, utilizing a modified $G/G/n$ queue, the stationarity of a quadratic test function, and a novel leave-one-out coupling technique. Finally, we also extend our method to $G/G/n$ queues with fully heterogeneous service-time distributions.
title A new $1/(1-ρ)$-scaling bound for multiserver queues via a leave-one-out technique
topic Probability
Performance
60K25 (Primary) 68M20, 90B22 (Secondary)
C.4; G.3; I.6
url https://arxiv.org/abs/2510.11015