Indoor positioning using pressure sensors

Abstract

The present disclose relates to position estimation in an indoor environment. In one example, a location server may receive a request for reference information from a wireless network device located in the indoor environment. The location server may determine a reference altitude and a reference pressure at the wireless network device. The location server may transmit the reference altitude and the reference pressure to the wireless network device for the wireless network device to determine its altitude in the indoor environment. The location server may also determine a reference horizontal position, and transmit the reference horizontal position to the wireless network device for the wireless network device to determine its horizontal position in the indoor environment.

What is claimed is: 
     
         1 . A method for position estimation, the method comprising:
 receiving, by a location server, a request for reference information from a wireless network device located in an indoor environment;   determining, by the location server, a reference altitude and a reference pressure at the wireless network device; and   transmitting, by the location server, the reference altitude and the reference pressure to the wireless network device for the wireless network device to determine its altitude in the indoor environment.   
     
     
         2 . The method of  claim 1 , wherein said determining a reference altitude and a reference pressure at the wireless network device comprises:
 determining, by the location server, a reference altitude and a reference pressure associated with a first access point located in the indoor environment.   
     
     
         3 . The method of  claim 2 , further comprising:
 determining, by the location server, multiple pressure and altitude measurements from a plurality of access points located in the indoor environment; and   transmitting, by the location server, the multiple pressure and altitude measurements to the wireless network device for the wireless network device to determine its altitude in the indoor environment based, at least in part, on the multiple pressure and altitude measurements.   
     
     
         4 . The method of  claim 2 , wherein said determining the reference altitude and the reference pressure associated with the first access point comprises:
 transmitting, by the location server, a message to the first access point requesting the first access point to provide the reference altitude and the reference pressure associated with the first access point; and   receiving, by the location server from the first access point, the reference altitude and the reference pressure associated with the first access point.   
     
     
         5 . The method of  claim 2 , wherein said determining the reference altitude and the reference pressure associated with the first access point comprises:
 receiving, by the location server, the reference pressure and the reference altitude from the first access point that the first access point received from a second wireless network device located in the indoor environment.   
     
     
         6 . The method of  claim 2 , further comprising:
 determining, by the location server, a reference horizontal position associated with the first access point; and   transmitting, by the location server, the reference horizontal position associated with the first access point to the wireless network device for the wireless network device to determine its horizontal position in the indoor environment.   
     
     
         7 . The method of  claim 6 , wherein said determining the reference altitude, the reference pressure, and the reference horizontal position associated with the first access point comprises:
 receiving, by the location server, a rebroadcast from the first access point of the reference pressure, the reference altitude, and the reference horizontal position received from a second wireless network device located in the indoor environment.   
     
     
         8 . The method of  claim 1 , wherein said determining a reference altitude and a reference pressure at the wireless network device comprises:
 determining a reference altitude of the location server and a reference pressure at the location server.   
     
     
         9 . The method of  claim 8 , wherein the reference pressure is determined using a pressure sensor of the location server. 
     
     
         10 . The method of  claim 1 , further comprising:
 determining, by the location server, a reference horizontal position, wherein said determining the reference horizontal position includes one of:
 determining, by the location server, a horizontal position of a first access point located in the indoor environment; or 
 determining, by the location server, a horizontal position of the location server. 
   
     
     
         11 . The method of  claim 10 , further comprising:
 transmitting, by the location server, the reference horizontal position to the wireless network device for the wireless network device to determine its horizontal position in the indoor environment.   
     
     
         12 . The method of  claim 1 , wherein the location server receives the request for reference information from the wireless network device when a first access point located in the indoor environment is not capable of determining a reference pressure associated with the first access point. 
     
     
         13 . The method of  claim 1 , further comprising:
 receiving, by the location server, contextual information associated with the indoor environment from the wireless network device; and   determining, by the location server, an altitude of the wireless network device based, at least in part, on the contextual information.   
     
     
         14 . The method of  claim 13 , wherein the contextual information includes at least one member selected from the group consisting of a building level where the wireless network device is located, a name of a shop closest to the wireless network device, and an image of the shop closest to the wireless network device. 
     
     
         15 . The method of  claim 1 , further comprising:
 determining that a first access point located in the indoor environment is not capable of determining a reference pressure and a reference altitude associated with the first access point;   determining a pressure and an altitude associated with a second wireless network device located in the indoor environment; and   using the pressure and the altitude associated with the second wireless network device as the reference pressure and the reference altitude of the first access point.   
     
     
         16 . The method of  claim 15 , further comprising:
 rebroadcasting the pressure and the altitude associated with the second wireless network device to a second access point located in the indoor environment.   
     
     
         17 . The method of  claim 1 , further comprising:
 transmitting a request for reference information from a first access point located in the indoor environment to a second access point located in the indoor environment.   
     
     
         18 . A location server comprising:
 a processor; and   a memory to store instructions, which when executed by the processor, cause the location server to:
 receive a request for reference information from a wireless network device located in an indoor environment; 
 determine a reference altitude and a reference pressure at the wireless network device; and 
 transmit the reference altitude and the reference pressure to the wireless network device for the wireless network device to determine its altitude in the indoor environment. 
   
     
     
         19 . The location server of  claim 18 , wherein the instructions that cause the location server to determine a reference altitude and a reference pressure at the wireless network device include instructions that cause the location server to:
 determine a reference altitude and a reference pressure associated with a first access point located in the indoor environment.   
     
     
         20 . The location server of  claim 19 , wherein the instructions, which when executed by the processor, further cause the location server to:
 determine multiple pressure and altitude measurements from a plurality of access points located in the indoor environment; and   transmit the multiple pressure and altitude measurements to the wireless network device for the wireless network device to determine its altitude in the indoor environment based, at least in part, on the multiple pressure and altitude measurements.   
     
     
         21 . The location server of  claim 18 , wherein the instructions, which when executed by the processor, further cause the location server to:
 determine a reference horizontal position based, at least in part, on one of a horizontal position of a first access point located in the indoor environment or a horizontal position of the location server.   
     
     
         22 . The location server of  claim 21 , wherein the instructions, which when executed by the processor, further cause the location server to:
 transmit the reference horizontal position to the wireless network device for the wireless network device to determine its horizontal position in the indoor environment.   
     
     
         23 . The location server of  claim 18 , wherein the instructions that cause the location server to determine a reference altitude and a reference pressure at the wireless network device include instructions that cause the location server to:
 determine a reference altitude of the location server and a reference pressure at the location server.   
     
     
         24 . The location server of  claim 23 , further comprising a pressure sensor configured to determine the reference pressure at the location server. 
     
     
         25 . The location server of  claim 19 , wherein the instructions, which when executed by the processor, further cause the location server to:
 determine a reference horizontal position associated with the first access point; and   transmit the reference horizontal position associated with the first access point to the wireless network device for the wireless network device to determine its horizontal position in the indoor environment.   
     
     
         26 . A non-transitory machine-readable storage medium having instructions stored therein, which when executed by a processor cause the processor to perform operations that comprise:
 receiving, by a location server, a request for reference information from a wireless network device located in an indoor environment;   determining, by the location server, a reference altitude and a reference pressure at the wireless network device; and   transmitting, by the location server, the reference altitude and the reference pressure to the wireless network device for the wireless network device to determine its altitude in the indoor environment.   
     
     
         27 . The non-transitory machine-readable storage medium of  claim 26 , wherein the operations for determining a reference altitude and a reference pressure at the wireless network device further comprise:
 determining, by the location server, a reference altitude and a reference pressure associated with a first access point located in the indoor environment.   
     
     
         28 . The non-transitory machine-readable storage medium of  claim 27 , wherein the operations further comprise:
 determining, by the location server, multiple pressure and altitude measurements from a plurality of access points located in the indoor environment; and   transmitting, by the location server, the multiple pressure and altitude measurements to the wireless network device for the wireless network device to determine its altitude in the indoor environment based, at least in part, on the multiple pressure and altitude measurements.