DAWN: Delay-Aware Wi-Fi Offloading and Network Selection

TL;DR

This paper introduces DAWN, a delay-aware Wi-Fi offloading and network selection algorithm that balances user payment and QoS for delay-tolerant applications, with proven threshold structure and low complexity.

Contribution

It proposes a novel delay-aware offloading algorithm with a threshold structure and a low-complexity approximation for general single-user scenarios.

Findings

High probability of completing file transfer under strict deadlines.

Lowest payment achieved under non-stringent deadlines.

Outperforms heuristic schemes in simulations.

Abstract

To accommodate the explosive growth in mobile data traffic, both mobile cellular operators and mobile users are increasingly interested in offloading the traffic from cellular networks to Wi-Fi networks. However, previously proposed offloading schemes mainly focus on reducing the cellular data usage, without paying too much attention on the quality of service (QoS) requirements of the applications. In this paper, we study the Wi-Fi offloading problem with delay-tolerant applications under usage-based pricing. We aim to achieve a good tradeoff between the user's payment and its QoS characterized by the file transfer deadline. We first propose a general Delay-Aware Wi-Fi Offloading and Network Selection (DAWN) algorithm for a general single-user decision scenario. We then analytically establish the sufficient conditions, under which the optimal policy exhibits a threshold structure in terms of both the time and file size. As a result, we propose a monotone DAWN algorithm that approximately solves the general offloading problem, and has a much lower computational complexity comparing to the optimal algorithm. Simulation results show that both the general and monotone DAWN schemes achieve a high probability of completing file transfer under a stringent deadline, and require the lowest payment under a non-stringent deadline as compared with three heuristic schemes.