Increasing the range of wireless passive sensor nodes using multisines

Wireless Sensor Networks (WSNs) usually consist of battery-powered nodes. Therefore, once the batteries deplete, the networks collapse. Passive sensor nodes are immune to this kind of problem because they do not have batteries, but on the other hand, their range is significantly shorter. This paper shows that this range can be enhanced (in a noticeable manner) if the Radio Frequency (RF) source that powers the nodes is set up to radiate a multisine waveform instead of a pure sinusoid, considering the same average power. The passive sensor used to demonstrate the usefulness of combining multiple sinusoidal waveforms is based on a low-power 16-bit microcontroller, and includes circuits for bi-directional wireless binary communication (envelope detection for downlink, backscatter for uplink). The sensor also features a 50Ω antenna port and an interface for debugging and expansion composed of 26 pins. Considering a power source of 2Werp, the maximum range of the wireless sensor (together with a half-wave dipole antenna) is 5.3 meters.

[1]  Gregory D. Durgin,et al.  Power-optimized waveforms for improving the range and reliability of RFID systems , 2009, 2009 IEEE International Conference on RFID.

[2]  Nuno Borges Carvalho,et al.  Maximizing DC power in energy harvesting circuits using multisine excitation , 2011, 2011 IEEE MTT-S International Microwave Symposium.

[3]  David Wetherall,et al.  Revisiting Smart Dust with RFID Sensor Networks , 2008, HotNets.

[4]  Dong Sam Ha,et al.  An overview of passive RFID , 2007, IEEE Communications Magazine.

[5]  Ian F. Akyildiz,et al.  Sensor Networks , 2002, Encyclopedia of GIS.

[6]  Özgür B. Akan,et al.  Wireless passive sensor networks , 2009, IEEE Communications Magazine.

[7]  Roy Want,et al.  Guest Editors' Introduction: Energy Harvesting and Conservation , 2005, IEEE Pervasive Comput..

[8]  D.J. Yeager,et al.  Wirelessly-Charged UHF Tags for Sensor Data Collection , 2008, 2008 IEEE International Conference on RFID.

[9]  Nuno Borges Carvalho,et al.  Design of a battery-free wireless sensor node , 2011, 2011 IEEE EUROCON - International Conference on Computer as a Tool.