A low power wireless transceiver for collaborative communication in wireless sensor networks
The most important constraint for wireless sensor networks is low power consumption. To reduce the power consumption, researchers have focused on collaborative beamforming because of its high energy efficiency. However, it suffers from frequency and phase synchronizations, and energy consuming data traffic necessary for data synchronization. A wireless sensor node architecture that solves all the aforementioned issues would be very complex, time-intensive, and energy consuming, diminishing its advantages. This dissertation focuses on two topics: a) an energy efficient data communication technique and b) a compatible low power wireless transceiver. A new energy efficient collaborative data transmission technique, called as subgroup modulation, exploits the existence of the frequency and phase offsets instead of trying to adjust them. Our theoretical and measurement results show that with the proposed technique SNR improves, even in the existence of mobile nodes. The results also show that the probability of error also reduces significantly. Secondly, a low-power wireless transceiver is proposed and designed to demonstrate the proposed technique. It employs current reuse, switch-less switching, and fast PLL on/off switching techniques to reduce the power, size, and cost of the sensor node. Implemented in 130-nm CMOS technology with a die area of 4mm2, 2.2-2.488GHz transceiver merges VCO, PA, LNA, TX/RX switch, and modulator into a common branch. The sensitivity measured for 0.1%BER in RX mode is -90dBm, one of the best among the published works. The power consumption of the proposed wireless transceiver can be reduced to a few μW levels by utilizing an energy-efficient scheduling.
Jung, Purdue University.
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