Green Modulation in Proactive Wireless Sensor Networks

Due to unique characteristics of sensor nodes, choosing energy-efficient modulation scheme with low-complexity implementation (refereed to as green modulation) is a critical factor in the physical layer of Wireless Sensor Networks (WSNs). This paper presents (to the best of our knowledge) the first in-depth analysis of energy efficiency of various modulation schemes using realistic parameters in IEEE 802.15.4 standard and present state-of-the art technology, to find the best scheme in a proactive WSN over Rayleigh and Rician flat-fading channel models with path-loss. For this purpose, we describe the proactive system model according to a pre-determined timebased process in practical sensor nodes. The present analysis also includes the effect of channel bandwidth and active mode duration on energy efficiency of popular modulation designs in the pass-band and Ultra-WideBand (UWB) categories. Experimental results show that among various pass-band and UWB modulation schemes, NonCoherent M-ary Frequency Shift Keying (NC-MFSK) with small order of M and On-Off Keying (OOK) have significant energy saving compared to other schemes for short range scenarios, and could be considered as realistic candidates in proactive WSNs. In addition, NC-MFSK and OOK have the advantage of less complexity and cost in implementation than the other schemes.