Green Modulations in Energy-Constrained Wireless Sensor Networks

TL;DR

This paper analyzes energy-efficient modulation schemes for wireless sensor networks, considering realistic channel models and practical system constraints, to identify optimal modulation strategies for different network conditions.

Contribution

It provides a comprehensive analysis of modulation schemes' energy efficiency in WSNs using realistic models, highlighting the optimal schemes for various scenarios.

Findings

Optimized NC-MFSK is most energy-efficient in sparse WSNs.

OOK outperforms NC-MFSK in dense WSNs with low path-loss.

Channel bandwidth and duty-cycling significantly impact energy consumption.

Abstract

Due to the unique characteristics of sensor devices, finding the energy-efficient modulation with a low-complexity implementation (refereed to as green modulation) poses significant challenges in the physical layer design of Wireless Sensor Networks (WSNs). Toward this goal, we present an in-depth analysis on the energy efficiency of various modulation schemes using realistic models in the IEEE 802.15.4 standard to find the optimum distance-based scheme in a WSN over Rayleigh and Rician fading channels with path-loss. We describe a proactive system model according to a flexible duty-cycling mechanism utilized in practical sensor apparatus. The present analysis includes the effect of the channel bandwidth and the active mode duration on the energy consumption of popular modulation designs. Path-loss exponent and DC-DC converter efficiency are also taken into consideration. In considering the energy efficiency and complexity, it is demonstrated that among various sinusoidal carrier-based modulations, the optimized Non-Coherent M-ary Frequency Shift Keying (NC-MFSK) is the most energy-efficient scheme in sparse WSNs for each value of the path-loss exponent, where the optimization is performed over the modulation parameters. In addition, we show that the On-Off Keying (OOK) displays a significant energy saving as compared to the optimized NC-MFSK in dense WSNs with small values of path-loss exponent.