Battery Power Efficiency of PPM and OOK in Wireless Sensor Networks

Sensor nodes in wireless sensor networks (WSNs) are often expected to operate on batteries for a long period of time. Battery power-efficiency is a critical factor dictating the lifetime of WSNs. In this paper, we compare two pulse-based modulations, namely pulse position modulation (PPM) and on-off keying (OOK), both of which are suitable for WSNs due to their low complexity transceivers. The comparison is based on a general model that integrates typical WSN transmission and reception modules with realistic nonlinear battery models. We analyze and compare the battery power-efficiency of PPM and OOK using coherent detection, and with bit error rate (BER) and cutoff rate criteria. Our results reveal that in sparse WSNs, PPM is more battery power-efficient. In dense WSNs, OOK outperforms PPM. In addition, the battery power-efficiency of OOK increases as the required cutoff rate decreases.