Assistance data cell selection based on interference estimates in a wireless communications system

Patent metadata

Field	Value
Publication number	US-9491680-B2
Application number	US-201414526169-A
Country	US
Kind code	B2
Filing date	Oct 28, 2014
Priority date	Oct 28, 2014
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

A method for assisting a mobile device to perform positioning measurements on positioning signals periodically transmitted by at least some of a plurality of cells in a wireless communication network includes determining an estimated position of the mobile device and then determining a first set of candidate cells of the plurality of cells based on the estimated position of the mobile device. The method also includes estimating an expected interference of each respective positioning signal that is transmitted by each candidate cell of the first set and selecting a subset of cells from the first set of candidate cells based on the estimated expected interference. Assistance data identifying the selected subset of cells is then generated and sent to the mobile device.

First claim

What is claimed is:

1. A method for assisting a mobile device to perform positioning measurements on positioning signals periodically transmitted by at least some of a plurality of cells in a wireless communication network, the method comprising:
determining an estimated position of the mobile device;
determining a first set of candidate cells of the plurality of cells in the wireless communication network based on the estimated position of the mobile device;
estimating an expected interference of each respective positioning signal that is transmitted by each candidate cell of the first set caused, at least in part, by transmission of signals by one or more other cells of the plurality of cells;
selecting a subset of cells from the first set of candidate cells based on the estimated expected interference;
generating assistance data that identifies the selected subset of cells; and
sending the generated assistance data to the mobile device.

2. The method of claim 1 , wherein determining an estimated position of the mobile device includes:
determining which of the plurality of cells is a serving cell of the mobile device; and
setting the estimated position of the mobile device to a center of the serving cell.

3. The method of claim 2 , wherein determining the estimated position of the mobile device further includes:
scaling a maximum antenna range of a base station included in the serving cell according to a relative power level of the base station; and
setting the estimated position of the mobile device to a center of the serving cell based on the scaled maximum antenna range.

4. The method of claim 1 , wherein determining the estimated position of the mobile device is based on a relative power level of each base station included in at least some of the plurality of cells.

5. The method of claim 1 , wherein determining the first set of candidate cells includes:
determining whether a distance between the estimated position of the mobile device and each base station included in at least some of the plurality of cells is within a threshold distance and whether the estimated position of the mobile device is within a maximum antenna range of the respective base station; and if so,
adding the respective cell to the first set of candidate cells.

6. The method of claim 1 , wherein estimating the expected interference of each respective positioning signal that is transmitted by each candidate cell of the first set includes estimating a threshold sensitivity at multiple serving power levels associated with various locations within the candidate cell.

7. The method of claim 1 , wherein estimating the expected interference of each respective positioning signal that is transmitted by each candidate cell of the first set includes:
determining which of the candidate cells is a serving cell of the mobile device;
determining a transmit frequency of the positioning signal transmitted by the serving cell; and
setting a threshold sensitivity to below a power level of the serving cell for each candidate cell of the first set having a transmit frequency that is the same as the transmit frequency of the serving cell.

8. The method of claim 1 , wherein selecting the subset of cells from the first set of candidate cells includes:
estimating a link margin at multiple locations within each candidate cell based on the estimated interference of each respective candidate cell;
estimating a probability of availability of the positioning signal for each candidate cell in response to the estimated link margin;
estimating a probability of ambiguity of the positioning signal for each candidate cell;
scoring each candidate cell in the first set based on the estimated probability of availability and the estimated probability of ambiguity; and
adding those candidate cells from the first set that have the highest scores to the subset of cells.

9. A non-transitory computer-readable medium including program code stored thereon for assisting a mobile device to perform positioning measurements on positioning signals periodically transmitted by at least some of a plurality of cells in a wireless communication network, the program code comprising instructions to:
determine an estimated position of the mobile device;
determine a first set of candidate cells of the plurality of cells in the wireless communication network based on the estimated position of the mobile device;
estimate an expected interference of each respective positioning signal that is transmitted by each candidate cell of the first set caused, at least in part, by transmission of signals by one or more other cells of the plurality of cells;
select a subset of cells from the first set of candidate cells based on the estimated expected interference;
generate assistance data that identifies the selected subset of cells; and
send the generated assistance data to the mobile device.

10. The medium of claim 9 , wherein the instructions to determine an estimated position of the mobile device includes instructions to:
determine which of the plurality of cells is a serving cell of the mobile device;
set the estimated position of the mobile device to a center of the serving cell;
scale a maximum antenna range of a base station included in the serving cell according to a relative power level of the base station; and
set the estimated position of the mobile device to a center of the serving cell based on the scaled maximum antenna range.

11. The medium of claim 9 , wherein the instructions to estimate the expected interference of each respective positioning signal that is transmitted by each candidate cell of the first set includes instructions to estimate a threshold sensitivity at multiple serving power levels associated with various locations within the candidate cell.

12. The medium of claim 9 , wherein the instructions to estimate the expected interference of each respective positioning signal that is transmitted by each candidate cell of the first set includes instructions to:
determine which of the candidate cells is a serving cell of the mobile device;
determine a transmit frequency of the positioning signal transmitted by the serving cell; and
set a threshold sensitivity to below a power level of the serving cell for each candidate cell of the first set having a transmit frequency that is the same as the transmit frequency of the serving cell.

13. The medium of claim 9 , wherein the instructions to select the subset of cells from the first set of candidate cells includes instructions to:
estimate a link margin at multiple locations within each candidate cell based on the estimated interference of each respective candidate cell;
estimate a probability of availability of the positioning signal for each candidate cell in response to the estimated link margin;
estimate a probability of ambiguity of the positioning signal for each candidate cell;
score each candidate cell in the first set based on the estimated probability of availability and the estimated probability of ambiguity; and
add those candidate cells from the first set that have the highest scores to the subset of cells.

14. An apparatus for assisting a mobile device to perform positioning measurements on positioning signals periodically transmitted by at least some of a plurality of cells in a wireless communication network, the apparatus comprising:
memory adapted to store program code; and
a processing unit coupled to the memory to access and execute instructions included in the program code to direct the apparatus to:
determine an estimated position of the mobile device;
determine a first set of candid

Assignees

• Qualcomm Inc

Inventors

• Moeglein Mark Leo
• Opshaug Guttorm R
• Gao Weihua
• Akgul Ferit

Classifications

• H04W64/00 Primary

  Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management · CPC title

• H04W52/285

  taking into account the mobility of the user · CPC title

• G01S5/10

  Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements {, e.g. omega or decca systems}(G01S5/12 takes precedence {; beacons and receivers cooperating therewith G01S1/306, G01S1/308}) · CPC title

• H04W4/02

  Services making use of location information · CPC title

• H04W36/30

  by measured or perceived connection quality data · CPC title