Method and apparatus for estimating location of a wireless station using multi-beam transmission

Abstract

A method and apparatus for estimating location of wireless stations in a wireless communication network are provided. An estimation of a bearing angle of a wireless station from a reference point of a multi-beam antenna pattern is made based on a plurality of beaming angles of a multi-beam antenna pattern and a received signal property, at the wireless station, of each of a plurality of wireless signals transmitted on respective beams of the multi-beam antenna pattern for each of the plurality of beaming angles.

1 . A method comprising:
 estimating a bearing angle from a reference point of a multi-beam antenna pattern to a wireless station based on a plurality of beaming angles of the multi-beam antenna pattern and a received signal property, at the wireless station, of each of a plurality of wireless signals transmitted on respective beams of the multi-beam antenna pattern for each of the plurality of beaming angles.   
     
     
         2 . The method of  claim 1 , further comprising:
 for each of the plurality of beaming angles of the multi-beam antenna pattern, transmitting each wireless signal of the respective plurality of wireless signals on a respective beam of the multi-beam antenna pattern.   
     
     
         3 . The method of  claim 1 , further comprising:
 steering a beam of the multi-beam antenna pattern toward the wireless station for communication with the wireless station based on the estimated bearing angle of the wireless station.   
     
     
         4 . The method of  claim 1 , wherein estimating a bearing angle from a reference point of the multi-beam antenna pattern to the wireless station comprises determining a beaming angle at which a ratio of the respective received signal property of at least two of the wireless signals transmitted on respective antenna beams of the multi-beam antenna pattern is substantially equal to a predetermined value. 
     
     
         5 . The method of  claim 4 , wherein, for each of the plurality of wireless signals transmitted on the respective beams of the multi-beam antenna pattern, the received signal property at the wireless station comprises a received level of a component of the wireless signal transmitted on the respective beam that is distinct from the wireless signals transmitted on the other beams of the multi-beam antenna pattern. 
     
     
         6 . The method of  claim 5 , wherein the predetermined value is substantially equal to one. 
     
     
         7 . The method of  claim 5 , wherein:
 the multi-beam antenna pattern comprises a first antenna beam and a second antenna beam; and   estimating the bearing angle comprises determining a beaming angle at which a ratio of the received signal property of the respective wireless signal transmitted on the first antenna beam to the received signal property of the respective wireless signal transmitted on the second antenna beam is substantially equal to the predetermined value.   
     
     
         8 . The method of  claim 7 , wherein:
 the multi-beam antenna pattern comprises a third antenna beam intermediate the first antenna beam and the second antenna beam; and   estimating the bearing angle comprises determining a beaming angle at which:   a ratio of the received signal property of the respective wireless signal transmitted on the first antenna beam to the received signal property of the respective wireless signal transmitted on the third antenna beam is substantially equal to a second predetermined value; and   a ratio of the received signal property of the respective wireless signal transmitted on the second antenna beam to the received signal property of the respective wireless signal transmitted on the third antenna beam is substantially equal to a third predetermined value.   
     
     
         9 . The method of  claim 8 , wherein the third antenna beam is substantially half-way between the first antenna beam and the second antenna beam, and the second predetermined value is substantially equal to the third predetermined value. 
     
     
         10 . The method of  claim 5 , further comprising:
 for each beaming angle, transmitting, to the wireless station, a code representative of the beaming angle.   
     
     
         11 . The method of  claim 10 , further comprising:
 receiving, from the wireless station, the code representative of the beaming angle at which the ratio of the respective received signal property of at least two of the wireless signals transmitted on respective antenna beams of the multi-beam antenna pattern is substantially equal to the predetermined value.   
     
     
         12 . The method of  claim 5 , further comprising:
 estimating a radial distance between the wireless station and the reference point of the multi-beam antenna pattern; and   estimating a location of the wireless station based on the estimated bearing angle of the wireless station from the reference point of the multi-beam antenna pattern and the estimated radial distance between the reference point of the multi-beam antenna pattern and the wireless station.   
     
     
         13 . The method of  claim 5 , wherein the plurality of wireless signals comprises any one of:
 orthogonal frequency division multiplex (OFDM) signals;   code division multiple access (CDMA) signals;   time division multiple access (TDMA) signals; and   pulse-based ultra wideband (UWB) signals.   
     
     
         14 . The method of  claim 2 , further comprising:
 for each of at least one additional multi-beam antenna pattern:   for each of a plurality of beaming angles of the additional multi-beam antenna pattern, transmitting a plurality of wireless signals on respective antenna beams of the additional multi-beam antenna pattern; and   estimating a bearing angle from a reference point of the additional multi-beam antenna pattern to the wireless station based on a received signal property, at the wireless station, of each of the plurality of wireless signals transmitted on the respective beams of the additional multi-beam antenna pattern for each of the plurality of beaming angles of the additional multi-beam antenna pattern.   
     
     
         15 . The method of  claim 14 , further comprising:
 estimating a location of the wireless station based on a location of intersection of the estimated bearing angle of the wireless station from the reference point of the first multi-beam antenna pattern and the respective estimated bearing angles of the wireless station from the respective reference points of each of the at least one additional multi-beam antenna pattern.   
     
     
         16 . The method of  claim 15  wherein estimating the location of the wireless station is determined based on the location of intersection of the estimated bearing angles of the wireless station from the plurality of multi-beam antenna patterns and hyperbolas representing estimated radial distances between the wireless station and the respective reference points of at least a subset of the plurality of multi-beam antenna patterns. 
     
     
         17 . The method of  claim 4 , further comprising:
 for each beaming angle, receiving a code representative of the beaming angle.   
     
     
         18 . The method of  claim 17 , further comprising:
 reporting the code representative of the beaming angle at which the ratio of the respective received signal property of at least two of the wireless signals transmitted on respective antenna beams of the multi-beam antenna pattern is substantially equal to the predetermined value.   
     
     
         19 . The method of  claim 18 , further comprising:
 estimating a location of the wireless station based on a location of intersection of the estimated bearing angle of the wireless station from the reference point of the first multi-beam antenna pattern and a respective estimated bearing angle of the wireless station from a respective reference point of each of at least one additional multi-beam antenna pattern.   
     
     
         20 . An apparatus comprising:
 a multi-beam antenna system configured to generate a multi-beam antenna pattern;   a beam steerer configured to steer the multi-beam antenna system to a plurality of beaming angles;   a radio frequency (RF) transmitter configured to generate a plurality of wireless signals at each beaming angle of the plurality of beaming angles, such that at each beaming angle, each wireless signal of the plurality of wireless signals is transmitted on a respective one of the antenna beams of the multi-beam antenna pattern generated by the multi-beam antenna system; and   a location estimation controller configured to estimate a bearing angle from a reference point of the multi-beam antenna pattern to a wireless station based on the plurality of beaming angles and a received signal property, measured at the wireless station, of each of the plurality of wireless signals transmitted on the respective antenna beams of the multi-beam antenna pattern for each of the plurality of beaming angles.   
     
     
         21 . The apparatus of  claim 20 , wherein the location estimation controller is configured to receive the received signal property of each of the plurality of wireless signals for each of the plurality of beaming angles from the wireless station. 
     
     
         22 . The apparatus of  claim 21 , wherein the location estimation controller is configured to estimate a bearing angle from a reference point of the multi-beam antenna pattern to the wireless station by determining a beaming angle at which a ratio of the respective received signal property of at least two of the wireless signals transmitted on respective antenna beams of the multi-beam antenna pattern is substantially equal to a predetermined value. 
     
     
         23 . The apparatus of  claim 22 , wherein the RF transmitter is configured to transmit a code representative of a current beaming angle of the plurality of beaming angles for each of the plurality of beaming angles. 
     
     
         24 . The apparatus of  claim 23 , wherein the location estimation controller is configured to receive, from the wireless station, the code representative of the beaming angle at which the ratio of the respective received signal property of at least two of the wireless signals transmitted on respective antenna beams of the multi-beam antenna pattern is substantially equal to the predetermined value.