A Cooperative Device Free Wireless Sensing Procedure Design and Over-The-Air Verification

In the emerging technology of integrated sensing and communication, the ideas of utilizing distributed user devices as probes to sense the surrounding device-free objects and environment has become popular in recent years. Nevertheless, only few of them have been implemented and brought up for real-world verification. In this paper, we propose a two-step device-free wireless sensing method and conduct over-the-air (OTA) tests using a 5G NR millimeter wave base station and commercial user equipment (UE) to validate the feasibility. In the first step, the base station, which supports a full-duplex operation at 28 GHz carrier frequency, performs coarse monostatic sensing. In the second step, the UEs, i.e., smartphones, measure NR downlink positioning reference signals of 100 MHz bandwidth and perform refined bistatic sensing. Our OTA results show that a position error of 0.33 meter can be achieved for a target object of 1.2× 1.5 size placed at 11.9 meter away from the base station.