Green modulation in dense Wireless Sensor Networks

Abstract

Emails: {abouei, kostas and pas}@comm.utoronto.ca. AbstractDue 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 models 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 system model according to a pre-determined time-based process in practical sensor nodes. The present analysis also includes the effect of 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, Non-Coherent 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 WSNs. In addition, NC-MFSK and OOK have the advantage of less complexity and cost in implementation than the other schemes.

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

“…Among various sinusoidal carrier-based modulation techniques, FSK has been found to provide a good compromise between simple radio architecture, low-power consumption, and requirements on linearity of the modulation scheme [2], [10], [19]. Also, this scheme is used in some IEEE standards (e.g., [20]).…”

“…In a practical WSN however, it is shown that minimizing the total energy consumption depends strongly on the active mode duration and the channel bandwidth. References [2], [6] and [10] address this issue in a point-to-point WSN, where a sensor node transmits an equal amount of data per time unit to a designated sink node. In [2], the authors show that uncoded MQAM is more energy-efficient than uncoded MFSK for short-range applications, while using convolutional coded MFSK over AWGN is desirable for longer distances.…”

“…To the best of our knowledge, there is no existing analysis on the energy efficiency of rateless coded modulation that considers the effect of channel bandwidth and active mode duration on the total energy consumption in a proactive WSN. This paper addresses this issue and presents the first in-depth analysis of the energy efficiency of LT codes with FSK, known as green modulation as described in [10]. The present analysis is based on a realistic model in proactive WSNs operating over a Rayleigh fading channel with path-loss.…”

“…114-115]. It is shown in [10] that the transmit energy consumption per each symbol for an uncoded MFSK with non-coherent detector is obtained as…”

“…where P LN A , P F ilr , P ED , P IF A and P ADC denote the power consumption of Low-Noise Amplifier (LNA), filters, envelop detector, IF amplifier and ADC, respectively [10]. Since, the power consumption during transient mode period T tr is governed by the frequency synthesizer in both transmitter and the receiver [4], the energy consumption during T tr is obtained as P tr T tr = 2P Sy T tr [2].…”