Indoor positioning method, apparatus and system

1. A method, comprising:

receiving at an apparatus and from a first location at least: a first radio signal transmitted by a first antenna element, a second radio signal transmitted by a second antenna element and a third radio signal transmitted by a third antenna element;

discriminating between the at least first, second and third radio signals received at the apparatus from the first location;

receiving location information related to the first location;

determining, from the received at least first, second and third radio signals displacement information that is dependent upon the relative displacements of the at least first, second and third antenna elements;

with a processor, estimating a single bearing using:

the discriminated at least first, second and third radio signals, and

the displacement information; and

estimating a position of the apparatus using:

the single bearing,

the location information related to the first location, and

constraint information, wherein the constraint information is different from the location information related to the first location and is determined independently of the received at least first, second and third radio signals.

2. A method as claimed in claim 1 , further comprising:

estimating a further bearing using at least fourth, fifth and sixth radio signals, received at the apparatus from a second location; and

using the further bearing as the constraint information to estimate the position of the apparatus.

3. A method as claimed in claim 1 , wherein the constraint information relates to a vertical displacement associated with the apparatus.

4. A method as claimed in claim 3 , wherein the constraint information is: stored in the apparatus, input by a user or received from a remote server.

5. A method as claimed in claim 1 , further comprising receiving data, from the first location or a remote server, to enable the first, second and third radio signals to be discriminated from one another.

6. A method as claimed in claim 1 , wherein a relative displacement between the first, second and third antenna elements is used to estimate the single bearing from the first location.

7. A method as claimed in claim 1 , wherein a relative difference in time of reception between the received first, second and third radio signals is used to estimate the single bearing from the first location.

8. A method as claimed in claim 1 , further comprising determining whether a line of sight between the apparatus and the first location is blocked, and estimating the position of the apparatus differently in dependence upon the determination.

9. A method as claimed in claim 1 , wherein a position of the first location is known on a map, and estimating the position of the apparatus includes locating the apparatus relative to the first location using the estimated single bearing.

10. An apparatus configured to:

receive from a first location at least: a first radio signal transmitted by a first antenna element, a second radio signal transmitted by a second antenna element and a third radio signal transmitted by a third antenna element;

receive location information related to the first location; and

determine, from the received at least first, second and third radio signals, displacement information that is dependent upon the relative displacements of the at least first, second and third antenna elements;

the apparatus comprising:

processing circuitry:

configured to discriminate between the at least first, second and third radio signals received at the apparatus from the first location;

configured to estimate a single bearing using:

the discriminated first, second and third radio signals, and

the displacement information; and

configured to estimate a position of the apparatus using:

the single bearing,

the location information related to the first location, and

constraint information, wherein the constraint information is different from the location information related to the first location and is determined independently of the received at least first, second and third radio signals.

11. An apparatus as claimed in claim 10 , wherein the processing circuitry is configured to:

estimate a further bearing using at least fourth, fifth and sixth radio signals received from a second location; and

use the further bearing as the constraint information to estimate the position of the apparatus.

12. An apparatus as claimed in claim 10 , where the constraint information relates to a vertical displacement associated with the apparatus.

13. A system comprising: a transmitter configured to transmit first, second and third radio signals, and an apparatus as claimed in claim 10 .

14. A non-transitory computer readable storage medium storing a computer program comprising computer program instructions that, when executed by processing circuitry of an apparatus, causes the apparatus to perform:

receiving from a first location at least: a first radio signal transmitted by a first antenna element, a second radio signal transmitted by a second antenna element and a third radio signal transmitted by a third antenna element;

discriminating between the at least first, second and third radio signals received at the apparatus from the first location;

receiving location information related to the first location;

determining, from the received at least first, second and third radio signals, displacement information that is dependent upon the relative displacements of the at least first, second and third antenna elements;

estimating a single bearing using:

the discriminated first, second, and third radio signals, and

the displacement information; and

estimating a position of the apparatus using:

the single bearing,

the location information related to the first location, and

constraint information, wherein the constraint information is different from the location information related to the first location and is determined independently of the received at least first, second and third radio signals.

15. A non-transitory computer readable storage medium as claimed in claim 14 , where the constraint information relates to a vertical displacement associated with the receiver.

16. An apparatus as claimed in claim 10 , wherein the constraint information is: stored in the apparatus, input by a user or received from a remote server.

17. An apparatus as claimed in claim 10 , further comprising:

a receiver configured to receive first second and third radio signals from a first location.

18. An apparatus as claimed in claim 10 , further comprising at least one memory storing computer program code, wherein the at least one memory and stored computer program code are configured, with the processing circuitry, to cause the apparatus to at least:

discriminate between the first, second and third radio signals;

estimate the bearing using the discriminated first, second and third radio signals; and

estimate, using the single bearing, the location information related to the first location and constraint information that is independent of the received first, second and third radio signals, a position of the apparatus.

19. A method as claimed in claim 1 wherein the received at least first, second and third radio signals have a transmission range of 100 meters or less.

20. An apparatus as claimed in claim 10 wherein the received at least first, second and third radio signals have a transmission range of 100 meters or less.

21. A method as claimed in claim 1 wherein the displacement information is:

derived from phase information of the received at least first, second and third signals, or

encoded in the received at least first, second and third radio signals.