Patent ID: 8219114
Filing Date: 2012-07-10
Classification: G01S,H04W

Abstract:
1. A method of providing a location of a wireless mobile device within a building structure to a cellular network, the method comprising: at each pseudo-random number (PN) based probe of a plurality of PN-based probes respectively located within one or more ventilation ducts of an HVAC system of the building structure, each PN-based probe having a distinct PN offset and being communicatively coupled with the cellular network, receiving a common wireless signal transmitted from the wireless mobile device; determining a respective distance between the wireless mobile device and each respective PN-based probe based on a respective propagation delay of the common wireless signal received at the respective PN-based probe; and transmitting information indicative of each respective distance to the cellular network, wherein determining the respective distance between the wireless mobile device and each respective PN-based probe based on the respective propagation delay of the common wireless signal received at the respective PN-based probe comprises: for each respective PN-based probe of the plurality of PN-based probes, determining a respective radial distance based on the respective propagation delay, wherein the respective radial distance corresponds to a sum of a free-space path between the wireless mobile device and an opening in a ventilation duct of the HVAC system and a waveguide path within the HVAC system between the opening and the respective PN-based probe; defining a respective radial shell about each respective PN-based probe based on the respective radial distance determined for the respective PN-based probe, and determining a region of overlap of all the respective radial shells; determining a measured location of the wireless mobile device to be within the region of overlap; and for each respective PN-based probe of the plurality of PN-based probes, determining the respective distance between the wireless mobile device and the respective PN-based probe as a free-space distance from the respective PN-based probe to the measured location of the wireless mobile device.