Energy-Delay Considerations in Coded Packet Flows

TL;DR

This paper analyzes the energy-delay trade-offs in a line network with packet erasures using network coding, providing queueing theoretic insights and optimal transmission strategies for minimizing delay and energy consumption.

Contribution

It introduces a queueing model for coded packet flows in erasure networks and derives optimal coding strategies to minimize delay and energy.

Findings

Optimal number of coded packets depends on link erasures and arrival rates.

Delay and energy consumption are analytically characterized for genie-aided scenario.

Stopping rules for transmission improve efficiency in coded packet flows.

Abstract

We consider a line of terminals which is connected by packet erasure channels and where random linear network coding is carried out at each node prior to transmission. In particular, we address an online approach in which each terminal has local information to be conveyed to the base station at the end of the line and provide a queueing theoretic analysis of this scenario. First, a genie-aided scenario is considered and the average delay and average transmission energy depending on the link erasure probabilities and the Poisson arrival rates at each node are analyzed. We then assume that all nodes cannot send and receive at the same time. The transmitting nodes in the network send coded data packets before stopping to wait for the receiving nodes to acknowledge the number of degrees of freedom, if any, that are required to decode correctly the information. We analyze this problem for an infinite queue size at the terminals and show that there is an optimal number of coded data packets at each node, in terms of average completion time or transmission energy, to be sent before stopping to listen.