Ultra low power and interference robust transceiver techniques for wireless sensor networks

Abstract

Wireless sensor networks (WSNs) have the potential to build breakthrough technologies for a variety of applications to improve human life. Some of the important applications are prevention, prediction and rescue of disasters, medical study and cure, improve the energy efficiency of homes and industries and study environments in remote places. These applications desire an ultra low power sensor node to extend the battery life, so that minimum or zero maintenance is required after initial installation. With the advancement of CMOS technology, power consumption of processors and semiconductor memories has reduced drastically. However, the radio transceiver power consumption has not experienced much power reduction because of its RF analog circuits. This makes the transceiver the bottleneck with respect to lifetime in existing sensor nodes. Another growing challenge for the sensor node transceiver is its interference robustness. Therefore there is a need of ultra low energy and interference robust wireless transceivers to enable WSNs to thrive in several applications which are not yet successful. This thesis targets an energy optimized and interference-robust radio communication system for WSNs. Special focus is given to the receiver, as the receiver is either always ON or ON for more time than the transmitter for duty-cycled radio and hence it is the critical part of the transceiver performance both in terms of power reduction and interference mitigation. A system level optimization of the transceivers is carried out, and circuit techniques are proposed to reduce the receiver power consumption. sensornetwerken gebaseerd op andere communicatiestandaarden te verbeteren. v Contents Contents vii List of Figures xi Nomenclature xiv acknowledgement xiv B.1 Chirp synchronization circuit block diagram for the chirped-LO