- Energy Improvement in Radio Processing
Sensors that last: Using ultrasound for wireless communication, allowing sensors to stay in field ten times longer.
This project proposal presents the next steps, in the development of a ultrasound data communication system, aimed towards commercializing the system for application in wireless sensor nodes. Traditional RF-based wireless communications for small-form-factor devices like sensors or mobiles use carrier frequencies of hundreds of MHz to several GHz. The associated electronic receivers and transmitters must be designed to handle these high speeds. This results in substantial power dissipation so that regular battery replacements are required, which are both difficult and costly. Thus, the main receiver has to be duty-cycled to prolong battery lifetime. Wake-up is among the lowest power schemes to accomplish this; an always-ON low power receiver called the wake-up receiver is used to turn ON the main receiver when needed, the node power consumption is then dominated by the wake-up receiver. We drastically reduce this wake-up receiver power consumption and hence, the overall node power consumption, by using ultrasonic wake-up instead of conventionally used RF-based wake-up; thanks to much lower circuit speeds (40kHz) facilitated by using ultrasound. In preceding academic research, measurements were done on an ultrasound data network consisting of three receivers and one transmitter. At the heart of the system is an ultra-low power ultrasonic receiver integrated circuit (IC), which achieves a ten-fold reduction in power consumption over the state-of-the-art RF-based receivers. However, to prepare this technology for the commercial arena, more technical work will be conducted in understanding the effect of reverberations on system performance, in increasing the communication-distance range and in increasing the communication data rate. Commercial partnerships have been formed with sensor node manufacturers, which give us access to real-life environments and allow us to base our technology development on measurements done in real application environments. This is especially important for wireless ultrasound, which is not a well understood communication medium. Further, technology demonstrations will be given to commercial partners and potential customers by using the prototypes that we have developed so far.
Ultra-low power communication circuitry, realizable by using ultrasound, makes our technology desirable for the applications of environmental, HVAC and surveillance sensors. However, there are several other benefits in using ultrasound data for wireless sensors. Ultrasonic communication modules can be made at much lower costs compared to commercially available RF-based modules (Zigbee transceivers) because of low costs of ceramic-based ultrasonic transducers. Also, ultrasound doesn’t cause electromagnetic interference, resulting in quicker FCC approvals for EMI/EMC compliance for OEM manufactures.
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I am a fifth (final) year doctoral student at Columbia University. Ultrasonic wireless sensors is a continuation of my research. Thus, I have a first-hand experience of the design steps involved in the making the ultrasound data communication system proposed here.
Together with the other two team members on this project, I am co-author on a provisional patent on using ultrasound data in wireless sensor nodes and have also presented the work in leading academic conferences. After my graduation in May, I plan to work towards commercializing this technology. As a preparation for this, I have been talking to potential customers to understand the technical requirements better. Further, I am a PI (Principle Investigator) on a related NSF Phase I SBIR grant that has been recommended for funding starting this June. Thus, the team, with its expertise in the design of both the electrical and mechanical systems and subsequent system co-design, is well positioned to carry out the proposed work.