Energy Optimal Transmission Scheduling in Wireless Sensor Networks

TL;DR

This paper introduces an energy-efficient transmission scheduling method for wireless sensor networks that leverages varying levels of channel information, modeled as a finite-state Markov channel, to optimize power use while meeting data deadlines.

Contribution

It proposes a practical transmission controller based on dynamic programming that uses low-grade channel information from ACK/NAK feedback, improving energy efficiency in sensor networks.

Findings

Scheduler achieves near-optimal throughput at low power levels.

Finite-state Markov channel capacity with feedback is characterized.

Method is implementable and adapts to channel dynamics.

Abstract

One of the main issues in the design of sensor networks is energy efficient communication of time-critical data. Energy wastage can be caused by failed packet transmission attempts at each node due to channel dynamics and interference. Therefore transmission control techniques that are unaware of the channel dynamics can lead to suboptimal channel use patterns. In this paper we propose a transmission controller that utilizes different "grades" of channel side information to schedule packet transmissions in an optimal way, while meeting a deadline constraint for all packets waiting in the transmission queue. The wireless channel is modeled as a finite-state Markov channel. We are specifically interested in the case where the transmitter has low-grade channel side information that can be obtained based solely on the ACK/NAK sequence for the previous transmissions. Our scheduler is readily implementable and it is based on the dynamic programming solution to the finite-horizon transmission control problem. We also calculate the information theoretic capacity of the finite state Markov channel with feedback containing different grades of channel side information including that, obtained through the ACK/NAK sequence. We illustrate that our scheduler achieves a given throughput at a power level that is fairly close to the fundamental limit achievable over the channel.