Patent ID: 9645225
Date: 2017-05-09
CPC Classifications: G01S,H04L,H04W

Claim:
1. A method of preparing data for determining a position of a mobile station, comprising: receiving information from a plurality of eavesdropping devices, the information from each respective one of the plurality of eavesdropping devices comprising signal strength information of a respective signal received at the respective one of the plurality of eavesdropping devices from each of the mobile station and a wireless access point; selecting a subset of the plurality of eavesdropping devices based at least in part on the signal strength information, the subset of the plurality of eavesdropping devices comprising at least three of the plurality of eavesdropping devices; obtaining information, from each respective eavesdropping device of the subset of the plurality of eavesdropping devices, the information comprising an indication of a time difference representing a difference in a time of arrival at the respective eavesdropping device of a respective initial packet sent by the mobile station and a time of arrival of a respective response packet sent by the wireless access point responsive to the respective initial packet; determining a refined processing delay based upon the indications of the time differences from the subset of the plurality of eavesdropping devices by combining the information received from each of the subset of the plurality of eavesdropping devices, the information received comprises processing delay estimates computed by each of the plurality of eavesdropping devices, wherein each processing delay estimate represents an estimated amount of time that the wireless access point took to process a respective initial packet from the mobile station and to generate the respective response packet; and determining the position of the mobile station based upon the refined processing delay and the time differences from the subset of the plurality of eavesdropping devices.