Cooperative fall detection using Doppler radar and array sensor

Doppler radar-based fall detection has been attractive due to its low cost and high detection performance. However, fall detection based on Doppler signatures is affected by the spatial variance due to the multipath and non-line-of-sight (NLOS) effects, which has been one of the key issues for detection performance in current Doppler radar-based systems. Moreover, the drawbacks of Doppler radar are the limited measurement range and sensitivity to the target's falling directions. In this paper, we present a cooperative fall detection system that uses a Doppler radar and an array sensor which can be used even for multipath and NLOS environments. We analyze the impact of Doppler signatures in multipath and NLOS environments and account for undesirable Doppler measurements. We use the temporal-spatial characteristics of the signals using an array sensor and propose a novel fall detection system, which cooperates with the Doppler radar to enhance fall detection performance in multipath and NLOS environments. We evaluate the proposed system performance in a typical laboratory environment in LOS and NLOS conditions. The experimental results show that the proposed system reduces the false alarm rate and improves true positive rate. Moreover, our proposed system can significantly enhance the fall detection accuracy compared with the corresponding only Doppler radar-based approach.