Patent ID: 8228171
Filing Date: 2012-07-24
Classification: G01S,H04Q

Abstract:
1. A radio frequency identification method for locating a listening tag using beacon tags comprising: transmitting a reader signal by a reader; receiving the reader signal by a plurality of beacon tags; receiving the reader signal by a listening tag; transmitting, respectively by the plurality of beacon tags, a plurality of beacon signals, wherein each of the plurality of beacon signals respectively comprises: in response to the listening tag receiving the plurality of beacon signals, calculating by the listening tag neighbor distances for each of the plurality of beacon tags based on a combination of: wherein, to compute the neighbor distances, the listening tag computes a delay time between the time at which the listening tag receives the reader signal and the time at which the listening tag respectively receives the plurality beacon signals, in order for the listening tag to subtract the constant processing time; wherein the neighbor distances are individual distances from the listening tag to each of the plurality of beacon tags; storing a list by the listening tag, wherein the list comprises: transmitting, by the listening tag, to the reader: calculating a geographical position of the listening tag based on: