Power Aware Wireless File Downloading: A Lyapunov Indexing Approach to A Constrained Restless Bandit Problem

TL;DR

This paper develops a Lyapunov indexing approach to optimize power-aware file downloading in multi-user systems, modeling the problem as a generalized restless bandit and proposing an efficient online heuristic.

Contribution

It introduces a novel Lyapunov-based index policy for power-aware throughput maximization in multi-user file downloading, extending single-user solutions to a scalable multi-user heuristic.

Findings

The single-user algorithm maximizes throughput under power constraints.

The multi-user heuristic is throughput optimal without power constraints.

Simulations show the heuristic's near-optimal performance across various scenarios.

Abstract

This paper treats power-aware throughput maxi-mization in a multi-user file downloading system. Each user can receive a new file only after its previous file is finished. The file state processes for each user act as coupled Markov chains that form a generalized restless bandit system. First, an optimal algorithm is derived for the case of one user. The algorithm maximizes throughput subject to an average power constraint. Next, the one-user algorithm is extended to a low complexity heuristic for the multi-user problem. The heuristic uses a simple online index policy. In a special case with no power-constraint, the multi-user heuristic is shown to be throughput optimal. Simulations are used to demonstrate effectiveness of the heuristic in the general case. For simple cases where the optimal solution can be computed offline, the heuristic is shown to be near-optimal for a wide range of parameters.