On the Energy Efficiency of LT Codes in Proactive Wireless Sensor Networks

TL;DR

This paper analyzes the energy efficiency of LT codes with FSK modulation in wireless sensor networks over Rayleigh fading channels, demonstrating that optimized LT coding offers superior energy savings for longer distances.

Contribution

It provides a comprehensive analysis of LT codes' energy efficiency in WSNs, highlighting their adaptability and advantages over traditional coding schemes in practical scenarios.

Findings

LT codes are most energy-efficient for distances greater than a threshold d_T.

Optimized LT coded FSK outperforms uncoded FSK and classical codes for d > d_T.

Energy gap between LT coded and uncoded FSK is negligible for d < d_T.

Abstract

This paper presents an in-depth analysis on the energy efficiency of Luby Transform (LT) codes with Frequency Shift Keying (FSK) modulation in a Wireless Sensor Network (WSN) over Rayleigh fading channels with pathloss. We describe a proactive system model according to a flexible duty-cycling mechanism utilized in practical sensor apparatus. The present analysis is based on realistic parameters including the effect of channel bandwidth used in the IEEE 802.15.4 standard, active mode duration and computation energy. A comprehensive analysis, supported by some simulation studies on the probability mass function of the LT code rate and coding gain, shows that among uncoded FSK and various classical channel coding schemes, the optimized LT coded FSK is the most energy-efficient scheme for distance d greater than the pre-determined threshold level d_T , where the optimization is performed over coding and modulation parameters. In addition, although the optimized uncoded FSK outperforms coded schemes for d < d_T , the energy gap between LT coded and uncoded FSK is negligible for d < d_T compared to the other coded schemes. These results come from the flexibility of the LT code to adjust its rate to suit instantaneous channel conditions, and suggest that LT codes are beneficial in practical low-power WSNs with dynamic position sensor nodes.