Powering the Next Billion Devices with Wi-Fi (1505.06815v1)

Abstract: We present the first power over Wi-Fi system that delivers power and works with existing Wi-Fi chipsets. Specifically, we show that a ubiquitous piece of wireless communication infrastructure, the Wi-Fi router, can provide far field wireless power without compromising the network's communication performance. Building on our design we prototype, for the first time, battery-free temperature and camera sensors that are powered using Wi-Fi chipsets with ranges of 20 and 17 feet respectively. We also demonstrate the ability to wirelessly recharge nickel-metal hydride and lithium-ion coin-cell batteries at distances of up to 28 feet. Finally, we deploy our system in six homes in a metropolitan area and show that our design can successfully deliver power via Wi-Fi in real-world network conditions.

• The paper introduces PoWiFi, a novel system that integrates wireless power delivery into standard Wi-Fi protocols by modifying router transmissions.
• It employs a multi-channel harvester that efficiently converts energy across multiple 2.4 GHz channels while maintaining network throughput.
• Real-world deployments validate PoWiFi's ability to power IoT sensor prototypes at ranges up to 28 feet without perceptible disruption to users.

A Technical Overview of "Powering the Next Billion Devices with Wi-Fi"

The paper "Powering the Next Billion Devices with Wi-Fi" details the development of a novel system, PoWiFi, which utilizes existing Wi-Fi infrastructure to provide wireless power to devices. This investigation into far-field wireless power transmission showcases the potential of Wi-Fi routers not just as communication tools, but as viable sources for powering small electronic devices without significantly affecting network performance.

Core Innovations

The central contribution of this work is the integration of power delivery into the well-established Wi-Fi communication protocol. The authors introduce PoWiFi, designed to deliver energy using existing Wi-Fi chipsets. By modifying the transmission patterns of Wi-Fi routers, the system sustains high cumulative channel occupancy, enabling efficient power harvesting while minimizing any deterioration in network throughput or user experience.

System Components

PoWiFi utilizes a dual-faceted approach, consisting of:

1. Multi-Channel Harvester: The PoWiFi system employs a novel multi-channel harvester circuit capable of efficiently collecting power from multiple 2.4 GHz Wi-Fi channels. The harvester design co-opts components such as rectifiers, matching networks, and DC-DC converters to address impedance mismatches across frequencies, thereby enhancing power conversion efficiency.
2. Router Transmission Design: The system implements a strategy where small, unintrusive power packets are broadcast across multiple Wi-Fi channels. This approach optimizes the channel usage without interfering significantly with client traffic. A sophisticated packet drop mechanism ensures that client needs are prioritized when network congestion occurs.

Performance Evaluation

The authors demonstrate PoWiFi’s practical utility by integrating the multi-channel harvester into battery-free and battery-recharging sensor prototypes for temperature sensing and camera capturing. In a series of experiments conducted in both controlled and real-world environments, the system successfully powered sensors at significant ranges (up to 28 feet for battery-recharging configurations) without perceptible disruption to regular Wi-Fi users.

Deployment and Implications

In an insightful real-world evaluation, the authors deployed PoWiFi in multiple residential settings, observing its performance over typical usage periods. The deployments verified that PoWiFi maintains high cumulative occupancy while remaining in the bounds of spectrum fairness and regulatory compliance.

Furthermore, the potential applications of PoWiFi extend beyond static sensors to mobile and wearable devices. By harnessing ubiquitous Wi-Fi infrastructure, PoWiFi presents a feasible means of charging devices in scenarios where traditional power sources are not available or practical.

Future Prospects

The implications of this research involve a transformative shift in the deployment of Internet of Things (IoT) devices. As IoT components proliferate, powering them without manual intervention becomes essential. The approach of utilizing Wi-Fi not only capitalizes on existing infrastructure but also invites future enhancements, potentially integrating support across multiple ISM bands for optimized energy delivery.

In conclusion, this work proposes a scalable solution to the challenge of wirelessly powering IoT and small-scale devices. By aligning power delivery with one of the most widespread communication protocols, the research addresses both a visionary and practical demand of modern ubiquitous computing systems. While challenges remain, particularly concerning regulatory aspects and technology integration, the paper represents a promising strategy for facilitating the next wave of connected devices.