http://www.cs.ucd.ie/ Ruzzelli, Cotan O’Hare, Tynan, Protocol assessment issues in low duty cycle sensor networks: The switching energy A.G. Ruzzelli, P. Cotan*, G.M.P. O’Hare, R. Tynan, and P.J.M Havinga** Adaptive Information Cluster (AIC) group @ PRISM Laboratory School of Computer Science and Informatics, University College Dublin (UCD), Ireland. *Department of Electronic Engineering, Technical University of Catalonia, Spain. **Department of Computer Science, University of Twente, The Netherlands.
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• Energy consumption mainly due to the transceiver activity;
• Protocol energy assessment based on transceiver states:– Transmit time;– Receive time;– Idle time (Sleeping time in sensor-nets);– Switching time (USUALLY NOT ASSESSED);
• Switching energy negligible in ad-hoc wireless network protocol assessment (e.g. WiFi);
• Energy consumption: primary objective • The wake-up concept • Very low duty cycle (even less than 5%) • Small packets smaller than in ad-hoc networks (e.g.
temperature data is few bytes)• Low data traffic per node
Can we consider switching energy still negligible for low duty cycle sensor networks?
The measuring circuit• Based on INA110 instrumentation amplifier
fast settling time and high slew rate device.
• Two resistors used: “low power mode” and “Tx/Rx mode”.
• Test performed by a square waveform of 1 kHz and of 5 V amplitude at the input of the INA 110 connected through an attenuating resistive divider circuit.
• Good precision and low distortion for conducting measurements at the
Considerations and guidelinesConsidering 5% as the lower bound of energy consumption significance:
– For TR1001 and CC1010, the switching energy needs to be computed if the node duty cycle is equal to or less than 3% and 3.6% respectively;
– For CC1000, the switching energy needs to be computed if the node duty cycle is equal to or less than 2.7% and 3.6% respectively;
– Sleeping energy consumption of TR1001 can be neglected in any case simulated as less than 2%;
– For CC1000 and CC1010 in low traffic load conditions, the transmitting energy becomes significant at 2.5% duty cycle or lower.
• Although similar, total energy consumptions might greatly differ in their inner energy usage composition The choice of a protocol to use is not only based on the application but also on the radio on board
• Values of switching energy have been obtained by direct measurements on different boards;
• The measurements have been applied to the SMAC protocol;
• Considerations and protocol assessment guidelines have been derived;
• In low duty cycle sensor-nets, the switching energy should be computed together with transmitting, receiving and sleeping energies;
• The obtained results help improve the MAC protocol evaluation process and empowers decisions relating to the judicious protocol/hardware choice for an specific set of WSN applications;
• Switching energy is expected to account for an even more significant percentage of the total power consumed as the duty cycle get closer to 1% such as in BMAC;
• Future work activities include the investigation of TDMA protocols that allow lower node duty cycle and more complex topologies.