Delay-Based Back-Pressure Scheduling in Multihop Wireless Networks

TL;DR

This paper introduces a delay-based scheduling scheme for multihop wireless networks that achieves optimal throughput and reduces packet delays, addressing the limitations of traditional queue-length-based methods.

Contribution

It proposes a novel delay metric-based scheduling scheme that is proven to be throughput-optimal in multihop scenarios with fixed routes.

Findings

Achieves the same throughput region as queue-length-based schemes.

Successfully reduces excessive packet delays.

Validated through simulations supporting analytical results.

Abstract

Scheduling is a critical and challenging resource allocation mechanism for multihop wireless networks. It is well known that scheduling schemes that favor links with larger queue length can achieve high throughput performance. However, these queue-length-based schemes could potentially suffer from large (even infinite) packet delays due to the well-known last packet problem, whereby packets belonging to some flows may be excessively delayed due to lack of subsequent packet arrivals. Delay-based schemes have the potential to resolve this last packet problem by scheduling the link based on the delay the packet has encountered. However, characterizing throughput-optimality of these delay-based schemes has largely been an open problem in multihop wireless networks (except in limited cases where the traffic is single-hop.) In this paper, we investigate delay-based scheduling schemes for multihop traffic scenarios with fixed routes. We develop a scheduling scheme based on a new delay metric, and show that the proposed scheme achieves optimal throughput performance. Further, we conduct simulations to support our analytical results, and show that the delay-based scheduler successfully removes excessive packet delays, while it achieves the same throughput region as the queue-length-based scheme.