Utilizing a reference signal for indoor positioning
Example methods, apparatuses, or articles of manufacture are disclosed herein that may be utilized, in whole or in part, to facilitate or support one or more operations or techniques for utilizing a reference signal for indoor positioning, such as for use in or with a mobile communication device, for example. In an implementation, a reference signal may be focused into a directed beam, for example using a phased antenna array, and rotated electronically through a sequence of directional angles in a horizontal plane. A mobile device may determine a most probable directional angle from one or more transmitters transmitting a directional beam, measure one or more parameters for each directional angle and determine a location estimate using, for example triangulation.
1. A method for locating a mobile device comprising:
receiving, at said mobile device, a directed beam transmitted by a wireless transmitter via a wireless signal in a sequence of directional angles in a horizontal plane, said wireless signal having been encoded with an indication of a directional angle of said sequence of directional angles of said directed beam;
decoding said wireless signal to obtain said indication of said directional angle;
obtaining at least one time of arrival (TOA) measurement related to said directional angle of said sequence of directional angles of said directed beam; and
determining a location of said mobile device based, at least in part, on said at least one TOA measurement and said indication of said directional angle.
2. The method of claim 1 , wherein said sequence of said directional angles comprises: a plurality of angles that change by discrete values; or a plurality of angles that change continuously between 0 and 360 degrees; or a combination thereof.
3. The method of claim 1 , wherein said sequence of directional angles is represented via: positive changes; or negative changes; or a combination thereof.
4. The method of claim 1 , wherein said sequence of directional angles rotates said directed beam around a circle in a clockwise direction; or counterclockwise direction; or a combination thereof.
5. The method of claim 1 , wherein said directional angle is relative to an absolute geographic direction or a magnetic direction.
6. The method of claim 1 , wherein said directional angle is relative to an orientation of said wireless transmitter.
7. The method of claim 1 , wherein said wireless signal comprises at least one of: a highly detectable pilot (HDP) signal or a positioning reference signal (PRS).
8. The method of claim 7 , wherein said HDP or said PRS signal comprises a reference signal having: a higher transmission power than that for other signals transmitted by said wireless transmitter; a different channel than that for other signals transmitted by said wireless transmitter; a signal modulation or encoding with better propagation or lesser attenuation or lower attenuation factor than that for other signals transmitted by said wireless transmitter; a known sequence of bits or symbols that may be received and coherently integrated over time by said mobile device; a muting by one or more other transmitters during said transmission by said wireless transmitter; a bit or symbol encoding sequence that is orthogonal to an encoding sequence used, at least in part, for one or more other reference signals transmitted by said wireless transmitter or reference signals transmitted by one or more other wireless transmitters; or a combination thereof.
9. The method of claim 1 , wherein said wireless signal is encoded with an identifier of said first wireless transmitter.
10. The method of claim 9 , wherein said identifier comprises at least one of the following: a media access control (MAC) address; a local ID; a network access ID; a cell ID; or any combination thereof.
11. The method of claim 1 , and further comprising:
receiving from a server a communication comprising at least one of: a location of said wireless transmitter; a start time for a sequence of directional angles for said wireless transmitter; or a combination thereof; and
determining said location of said mobile device based, at least in part, on said received communication.
12. The method of claim 1 , and further comprising:
obtaining a timing reference comprising at least one of: a round trip propagation time (RTT) to said wireless transmitter; an RTT to one or more other wireless transmitters; an observed time difference (OTD) between said wireless transmitter and one or more other wireless transmitters; and
determining said location of said mobile device based, at least in part, on said timing reference.
13. The method of claim 1 , wherein said sequence of directional angles targets a most likely location of said mobile device.
14. The method of claim 1 , wherein said sequence of directional angles targets an estimated location of said mobile device.
15. The method of claim 1 , and further comprising:
receiving one or more other wireless signals comprising one or more other directed beams transmitted by one or more other wireless transmitters, said one or more other directed beams being transmitted in respective sequences of directional angles in a horizontal plane;
obtaining a most probable directional angle for said one or more other directed beams;
decoding said one or more other wireless signals to obtain at least one other TOA measurement related to said most probable directional angle for said one or more other directed beams; and
determining said location of said mobile device based, at least in part, on said at least one other TOA measurement.
16. An apparatus comprising:
a mobile device comprising:
a wireless transceiver to communicate with an electronic communications network; and
one or more processors to:
receive, at said mobile device, a directed beam transmitted by a wireless transmitter via a wireless signal in a sequence of directional angles in a horizontal plane, said wireless signal having been encoded with an indication of a directional angle of said sequence of directional angles of said directed beam;
decode said wireless signal to obtain said indication of said directional angle;
obtain at least one time of arrival (TOA) measurement related to said directional angle of said sequence of directional angles of said directed beam; and
determine a location of said mobile device based, at least in part, on said at least one TOA measurement and said indication of said directional angle.
17. The apparatus of claim 16 , wherein said wireless signal comprises at least one of: a highly detectable pilot (HDP) signal or a positioning reference signal (PRS).
18. The apparatus of claim 16 , wherein said one or more processors further to:
receive one or more other wireless signals comprising one or more other directed beams transmitted by one or more other wireless transmitters, said one or more other directed beams being transmitted in respective sequences of directional angles in a horizontal plane;
determine a most probable directional angle for said one or more other directed beams;
obtain at least one other TOA measurement related to said most probable directional angle for said one or more other directed beams; and
determine said location of said mobile device based, at least in part, on said at least one other TOA measurement.
19. A non-transitory storage medium having instructions executable by a processor to:
receive, at a mobile device, a directed beam transmitted by a wireless transmitter via a wireless signal in a sequence of directional angles in a horizontal plane, said wireless signal having been encoded with an indication of a directional angle of said sequence of directional angles of said directed beam;
decode said wireless signal to obtain said indication of said directional angle;
obtain at least one time of arrival (TOA) measurement related to said directional angle of said sequence of directional angles of said directed beam; and
determine a location of said mobile device based, at least in part, on said at least one TOA measurement and said indication of said directional angle.