Wireless sensor networks (WSNs) deployed in the natural environment offer well-established benefits for prediction, modeling, timely response, and informed decision making in the face of the accelerating climate crisis. To facilitate faster experimentation and deployment, researchers have focused on developing WSN platforms that support rapid prototyping and field readiness. Despite their potential, these platforms have historically seen limited uptake both among domain scientists and the broader IoT research community. In this paper, we present insights gained from the development of ENTS (Environmental NeTworked Sensing)—a WSN platform co-designed with three distinct groups of domain scientists through an iterative development process. We describe the evolution of ENTS from a simple analog measurement tool to an extensible platform actively supporting collaborations with diverse domain experts. We synthesize our experience into a set of design principles aimed at fostering impactful and lasting research partnerships. Finally, we instantiate the outlined design principles for future interdisciplinary sensing efforts, including open-source hardware, firmware, low-cost custom weatherproof enclosures, and a web-based visualization tool.

Human studies often rely on wearable lifelogging cameras that capture videos of individuals and their surroundings to aid in visual confirmation or recollection of daily activities like eating, drinking, and smoking. However, this may include private or sensitive information that may cause some users to refrain from using such monitoring devices. Also, short battery lifetime and large form factors reduce applicability for long-term capture of human activity. Solving this triad of interconnected problems is challenging due to wearable embedded systems’ energy, memory, and computing constraints. Inspired by this critical use case and the unique design problem, we developed NIR-sighted, an architecture for wearable video cameras that navigates this design space via three key ideas: (i) reduce storage and enhance privacy by discarding masked pixels and frames, (ii) enable programmers to generate effective masks with low computational overhead, and (iii) enable the use of small MCUs by moving masking and compression off-chip. Combined together in an end-to-end system, NIR-sighted’s masking capabilities and off-chip compression hardware shrinks systems, stores less data, and enables programmer-defined obfuscation to yield privacy enhancement. The user’s privacy is enhanced significantly as nowhere in the pipeline is any part of the image stored before it is obfuscated. We design a wearable camera called NIR-sightedCam based on this architecture; it is compact and can record IR and grayscale video at 16 and 20+ fps, respectively, for 26 hours nonstop (59 hours with IR disabled) at a fraction of comparable platforms power draw. NIR-sightedCam includes a low-power Field Programmable Gate Array that implements our mJPEG compress/obfuscate hardware, Blindspot. We additionally show the potential for privacy-enhancing function and clinical utility via an in-lab eating study, validated by a nutritionist.

Wireless communication over long distances has become the bottleneck for battery-powered, large-scale deployments. Low-power protocols like Zigbee and Bluetooth Low Energy have limited communication range, whereas long-range communication strategies like cellular and satellite networks are power-hungry. Technologies that use narrow-band communication like LoRa, SigFox, and NB-IoT have low spectral efficiency, leading to scalability issues. The goal of this work is to develop a communication framework that is energy efficient, long-range, and scalable. We propose, design, and prototype WiChronos, a communication paradigm that encodes information in the time interval between two narrowband symbols to drastically reduce the energy consumption in a wide area network with large number of senders. We leverage the low data-rate and relaxed latency requirements of such applications to achieve the desired features identified above. We design and implement chirp spread spectrum transmitter and receiver using off-the-shelf components to send the narrowband symbols. Based on our prototype, WiChronos achieves an impressive 60% improvement in battery life compared to state-of-the-art LPWAN technologies in transmission of payloads less than 10 bytes at experimentally verified distances of over 4 km. We also show that more than 1,000 WiChronos senders can co-exist with less than 5% collision probability under low traffic conditions.

Wireless communication over long distances has become the bottleneck for battery-powered, large-scale deployments. Currently used low-power protocols such as Zigbee and Bluetooth Low Energy have limited communication range, whereas long-range communication strategies used in cellular and satellite networks are heavy on energy consumption. Methods that use narrow-band communication such as LoRa, SigFox, and NB-IoT have low spectral efficiency, leading to scalability issues. The goal of this work is to develop a communication framework that can satisfy the following requirements: (1) Increased battery life, (2) Longer communication range, (3) Scalability in a wireless network. In this work, we propose, design, and prototype WiChronos, a communication paradigm that encodes information in the time interval between two narrowband symbols in order to drastically reduce the energy consumption in a wide area network with a large number of senders. We leverage the low data-rate and relaxed latency requirements of such applications to achieve the desired features identified above. Based on our prototype using off-the-shelf components, WiChronos achieves an impressive 60% improvement in battery life compared to state-of-the-art LPWAN technologies at distances of over 800 meters. We also show that more than 1000 WiChronos senders can co-exist with less than 5% probability of collisions under low traffic conditions.

Power efficient wireless communication has become a bottleneck for long range and large scale deployments. We propose and prototype WiChronos, an energy efficient modulation technique for long range wireless communication in a large scale network. Using off-the-shelf (OTS) components, we demonstrate that WiChronos achieves an impressive 60% improvement in battery life compared to state-of-the-art LPWAN technologies at distances over 800 meters. We also show that more than 1000 WiChronos senders co-exist with less than 5% probability of collisions in low traffic conditions.