Smart all-time vision: The battery-free video communication for urban administration and law enforcement

The Chinese government is dedicated to enhancing the level of informatization in administrative law enforcement to ensure fairness and increase credibility. Currently, law enforcement has exposed such problems as insufficient force, difficulties in collecting evidence, and low evidential power. These problems contradict the principles of rule of law and standardization. Many local governments have implemented advanced information technologies for urban administration and law enforcement, including big data, artificial intelligence, and IoT. Among these technologies, IoT is the core communication infrastructure for innovative law enforcement platforms. However, traditional video communications rely on batteries or dedicated power sources, leading to maintenance challenges and high power consumption. In this paper, we propose AT-Eye, a new video communication paradigm for all-time law enforcement video monitoring, which is battery-free and high-throughput. The key enabler of AT-Eye is ambient backscatter technology, which enables energy harvesting and video communication simultaneously. Unlike previous methods, our proposal introduces a novel CCK-based modulation for tag cameras and achieves 4-way concurrency. The modulation is simple because it uses phase difference and it is energy-efficient because generating square waves is adequate. Moreover, to ensure full compatibility with COTS WiFi, we modulate the physical service data unit. Therefore, data recovery is possible using only commercial NICs. We conduct comprehensive experiments to examine our proposal and experiment results show that AT-Eye achieves a throughput of 10.8 Mbps with COTS radios. We also simulate a 16-way battery-free tag camera system, demonstrating AT-Eye's feasibility of high-definition video communication.