APPARATUS AND METHOD FOR POSITIONING A WIRELESS USER EQUIPMENT

• US 20110039574A1
• Filed: 08/17/2009
• Published: 02/17/2011
• Est. Priority Date: 08/17/2009
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Nokia Corporation
• Inventors: Koivisto, Tommi Tapani, Charbit, Gilles
• Granted Patent: US 8,248,997 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/0215 Interference
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

In accordance with an example embodiment of the present invention, a method is disclosed that comprises receiving a reference signal from each of at least two target neighbor cells via at least one receiving branch at a user equipment; estimating a timing range based at least on one of a timing advance for a serving cell and an inter-cell distance between the target neighbor cell and the serving cell; computing a reference signal time difference for the received reference signal from the target neighbor cell; and screening the computed reference signal time difference using the estimated timing range.

Claims

1. A method, comprising:

receiving a reference signal from each of at least two target neighbor cells via at least one receiving branch at a user equipment;

estimating a timing range based at least on one of a timing advance for a serving cell and an inter-cell distance between the target neighbor cell and the serving cell;

computing a reference signal time difference for the received reference signal from the target neighbor cell; and

screening the computed reference signal time difference using the estimated timing range.

2. The method of claim 1, further comprising applying a coherent detection to plurality of reference signals received from multiple receiving branches to select a shortest path.

3. The method of claim 2, further comprising applying non-coherent combining over the plurality of the reference signal received from the multiple receiving branches if the coherent detection fails to yield the shortest path.

4. The method of claim 2, further comprising applying the coherent detection to multiple reference signals received from the at least one receiving branch over multiple time slots to select the shortest path.

5. The method of claim 1, wherein estimating the timing range further comprises at least one of

setting a lower bound of the timing range to (d−

ta); and

setting an upper bound of the timing range to (d+ta), wherein d is the inter-cell distance between the serving cell and the target neighbor cell and ta is the timing advance.

6. The method of claim 5, wherein computing the reference signal time difference further comprises computing a time difference between a transmitting time of the reference signal and an observed arrival time of the reference signal for the target neighbor cell.

7. The method of claim 6, wherein screening the received reference signal further comprises discarding the received reference signal if the computed reference signal time difference is outside the estimated timing range.

8. The method of claim 7, further comprising determining a position of the user equipment based at least on the computed reference signal time difference from each of the at least two target neighbor cells and from the serving cell using a trilateration algorithm.

9. The method of claim 1, further comprising receiving from one of the serving cell and a serving mobile location center over a signaling channel at least one of

the inter-cell distance between the user equipment and the target neighbor cells;

the timing advance; and

a physical cell identifier (PCI) of the target neighbor cell to help computing the reference signal time difference for the received reference signal from the target neighbor cell.

10. An apparatus, comprising:

a radio interface module configured to receive a reference signal from each of at least two target neighbor cells via at least one receiving branch at the apparatus;

a positioning module configured to

estimate a timing range based at least on one of a timing advance for a serving cell and an inter-cell distance between the target neighbor cell and the serving cell;

compute a reference signal time difference for the received reference signal received from the target neighbor cell; and

screen the computed reference signal time difference using the estimated timing range.

11. The apparatus of claim 10, wherein the radio interface module includes at least two receiving branches configured to receive at least two reference signals and wherein the positioning module is further configured to apply a coherent detection to the at least two reference signals to select a shortest path.

12. The apparatus of claim 11, wherein the positioning module is further configured to apply the coherent detection to multiple reference signals received from one receiving branch over multiple time slots to select the shortest path.

13. The apparatus of claim 10, wherein the positioning module is further configured to adjust the timing range by narrowing down the timing range based at least on historical data of reference signal time differences.

14. The apparatus of claim 10, wherein each of the reference signals is one of a common reference signal, a provisional reference signal and a position reference signal.

15. The apparatus of claim 10, wherein the positioning module is further configured to estimate a location of the apparatus within the serving cell based at least on one of a direction of the received reference signal and a previous known position of the apparatus.

16. The apparatus of claim 15, wherein the positioning module is further configured to perform at least one of

identifying the at least two target neighbor cells based at least on one of a reference signal received power (RSRP), a reference signal received quality (RSRQ), a received power spectral density of the total noise and interference, and a received energy per resource element so that the at least two target neighbor cells are the strongest among all neighbor cells and directly face the apparatus;

and

receiving a signaling message from one of the serving cell and the serving mobile location center indicating the two target neighbor cells are strongest among all the neighboring cells and proximately face the apparatus.

17. The apparatus of claim 10, wherein the apparatus is part of a 4G mobile station or a 3GPP-compliant user equipment.

18. An apparatus, comprising:

at least one radio interface module configured to

receive from a coupled user equipment a transmitting time and an observed arrival time for a reference signal sent from a target neighbor cell; and

a positioning module configured to

estimate a timing range based at least on one of a timing advance and an inter-cell distance between the target neighbor cell and a serving cell where the apparatus is located;

compute a reference signal time difference for the reference signal based at least on the transmitting time and the observed arrival time; and

screen the computed reference signal time difference using the estimated timing range.

19. The apparatus of claim 18, wherein the positioning module is further configured to estimate a physical location of the user equipment within the serving cell based at least on a direction of arrival measurements at the serving cell and previous estimated positions within the serving cell.

20. The apparatus of claim 18, wherein the apparatus is one of a 4^th generation eNode B, a serving mobile location center and a Secure User Plane Location (SUPL) Location Platform (SLP).