Locating the node by exploiting shadowing fading

Shadowing fading is generally considered to be detrimental to node localization based on received signal strength (RSS). However, in this paper, we propose a new localization method which exploits shadowing fading to localize the node with unknown position. As we know that when a link comprised of the unknown node and an anchor node is blocked by an obstruction, the RSS of the link will be greatly attenuated. The shadowing fading can thus provide direction information with respect to the position of the unknown node because the largest shadowing loss is observed when the obstruction is located on the link. Motivated by this fact, an obstruction moves according to the predefined trajectory between an array of anchor nodes and the unknown node, resulting in large shadowing loss of the links. To localize the node, we extract the shadowing loss induced by the obstruction and employ the shadowing loss to estimate the time instants when the links are crossed. The link crossing time estimation is subsequently utilized to localize the unknown node by a least square (LS) method. The experimental result shows that the localization error of proposed method is about 0.33m, which is almost improved by 87% compared with conventional RSS-based localization method.