Abstract
Location-based services (LBSs) for elderly care is a trending topic in smart homes. The key issue is the high accurate positioning for the elderly. Ultra-wideband (UWB) is a centimeter-level positioning accuracy in line-of-sight (LOS) environments. However, most of existing UWB positioning methods need non-line-of-sight (NLOS) identification and compensation, and thus leading to severe deterioration in positioning accuracy in presence of complex indoor environments where the elderly lived. This article proposes a phase-difference-of-arrival (PDOA) assisted UWB positioning method (PDOA-UWB) for elderly care. In our positioning framework, we first calculate the phase difference of arrival from PDOA chip integrated in the UWB base stations (BSs) to obtain a coarse location of the elderly, which is further used to distinguish which nearby BSs are in LOS environments and which are in NLOS environments. Then, a PDOA-UWB positioning solution is derived to improve the positioning accuracy of the elderly. Compared with some existing methods, our method achieves higher accuracy with less NLOS compensation, and is easier to be implemented in complex indoor environments for simple practical engineering applications. Experimental results show the efficacy of our proposed method.
Highlights
The number of elderly people is increasing in developed countries and the healthcare services are being demanded to improve and maintain their health status and autonomy in homes or communities
Zj − z j=1 where [xj, yj, zj]T represents the j-th location estimate, [x, y, z]T is the true location of source, and J is the number of experiment trials
We first calculated the phase difference of arrival from PDOA chip integrated in the UWB base stations (BSs) to obtain a coarse location of the elderly
Summary
The number of elderly people is increasing in developed countries and the healthcare services are being demanded to improve and maintain their health status and autonomy in homes or communities. Doors and windows are the two main factors affecting the positioning accuracy of UWB techniques because the severe multipath propagation caused by doors and windows can result in severe NLOS propagation [10] Duan: Toward Elderly Care: A PDOA Assisted UWB Positioning Method in Smart Home which further results in location estimates with large bias. By using our BS, we can firstly estimate the coarse location of the elderly, which will be used to identify whether the required positioning BSs for positioning are in LOS environments or not In this case, we only need to compensate the signals from the BSs in NLOS environments.
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