The DARPA Near Zero Power RF and Sensor Operations (N-ZERO) program seeks to overcome the power limitations of persistent sensing by developing wireless, eventdriven sensing capabilities that allow physical, electromagnetic and other sensors to remain dormant-effectively asleep yet aware-until an event of interest awakens them. State-of-the-art sensors use active electronics to monitor the environment for such external triggers. The power consumed by these electronic circuits limits the sensor lifetime to durations of weeks to months. In contrast, N-ZERO seeks to exploit the energy in signal signatures to detect and recognize attention-worthy events, such as the presence of a particular machinery type or radio communications protocol, while rejecting noise and interference. This paper will discuss the new architectural approaches and component technologies being developed under the N-ZERO program, which are predicted to extend the lifetime of wireless sensors to several years under many operational scenarios.

The Near Zero Power RF and Sensor Operations (N-ZERO) program from DARPA has created a new, nanowatt class of intelligent sensors and RF receivers enabling systems that are passive or nearly passive while operating in an intelligent standby mode. Such systems can be persistently powered by small batteries for many years or perpetually via miniature energy harvesters. The program sought wake-up receivers with a sensitivity of -100dBm and physical sensors that could classify vehicles at a range of 10 m, with power consumption on order of the self-discharge rate of a small battery. Furthermore, researchers with designs that fit other applications, such as chemical and IR sensors, were open to participate as well. From the program multiple approaches have emerged featuring passive and active MEMS devices and subthreshold CMOS circuits. The overall goals of the program have helped to redefine the state-of-the art in ultra-low power receivers, machine learning processors, and passive physical sensors.

This paper overviews the Defense Advanced Research Projects Agency (DARPA) Adaptive RF Technologies (ART) and Arrays at Commercial Timescales (ACT) programs. These programs seek to create adaptable and reusable RF hardware in order to lower nonrecurring engineering development costs and timelines for RF systems and to allow RF hardware to be adapted to new missions after fielding. To achieve this vision, new RF architectures more amenable to reconfigurability have been developed along with component technologies that reduce the performance penalty associated with adaptive RF hardware.

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