A Long-Term Study Of mmWave Sensing In An Outdoor Urban Scenario

Sensing people with mmWave radars is gaining significant attention. This growing interest is due to two factors: radar monitoring provides more privacy than camera-based alternatives, and radio waves are not as easily blocked as light waves. Most mmWave studies, however, have three common characteristics. They are done indoors, without protecting the sensor (no casing), and the evaluation is performed for short periods of time. To assess the suitability of mmWave sensing in realistic outdoor scenarios, we deploy two nodes to track the flow of pedestrians over a period of three months. This longterm deployment provides three main contributions. First, we follow a detailed process to design a casing that can protect the sensors from harsh environmental conditions. Second, we install our nodes close to a set of cameras that were already deployed in the area. To compare the performance of both types of sensors, we propose a framework that considers the different coverage patterns of cameras and radars. Third, the time frame of our evaluation considers various types of weather, from sunny days to rainy and windy. Our results indicate that mmWave sensors need to be explored further outside the comfort zone of indoor spaces. To the best of our knowledge, this is the first long-term study assessing the reliability of radar sensors in the 60 GHz ISM band.