Method and apparatus for determining the identity of a femto cell

• US 9,307,465 B2
• Filed: 06/30/2011
• Issued: 04/05/2016
• Est. Priority Date: 06/30/2011
• Status: Active Grant

• Current Assignee: Viavi Solutions UK Limted (Lumentum Holdings Inc.)
• Original Assignee: Viavi Solutions UK Limted (Lumentum Holdings Inc.)
• Inventors: Flanagan, Michael Joseph
• Primary Examiner(s): Chang, Kent
• Assistant Examiner(s): Brittingham, Nathan
• Application Number:
  US13/173,923
• Publication Number:
  US 20130005326A1
• Time in Patent Office: 1,741 Days
• Field of Search: 370/331, 370/350, 455/456.1, 455/456.5, 455/456.6
• US Class Current: 1/1
• CPC Class Codes: H04W 36/04 Reselecting a cell layer in multi-layered cells
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

A femto cell is located within a macro cell of a wireless communication system. A method of identifying the femto cell comprises: determining at least one timing difference, the at least one timing difference being observed for communications between a wireless communication unit and each of a femto cell and at least one macro cell; and comparing the at least one observed timing difference to reference timing difference data. The identity of the femto cell may allow the location of the femto cell to be set as a geographical location for a wireless communication device that is within the footprint of the femto cell. The identity of the femto cell may allow hand in of an ongoing call, from the macro cell to the femto cell.

Claims

1. A method comprising:

determining, by a network device, a first observed timing difference observed for communications between a wireless communication unit and a femto cell associated with a macro cell;

determining, by the network device, a second observed timing difference observed for communications between the wireless communication unit and the macro cell;

calculating, by the network device, a timing difference value based on subtracting one of the first observed timing difference or the second observed timing difference from the other of the first observed timing difference or the second observed timing difference;

comparing, by the network device, the timing difference value to reference timing difference values,

each reference timing difference value being associated with a particular femto cell of a plurality of femto cells associated with the macro cell; and

identifying, by the network device, the femto cell, from among the plurality of femto cells, based on comparing the timing difference value to a reference timing difference value, of the reference timing difference values, associated with the femto cell,

the timing difference value being indicative of the femto cell, and

the reference timing difference value being based on mapped data created from data previously obtained by multiple wireless communication units.

2. The method of claim 1, further comprising:

receiving, from the wireless communication unit, observed timing data for the femto cell and the macro cell; and

where determining the first observed timing difference and determining the second observed timing difference includes;

determining the first observed timing difference and the second observed timing difference based on the observed timing data.

3. The method of claim 1, where the first observed timing difference comprises a timing offset value for the femto cell and the second observed timing difference comprises a timing offset value for the macro cell;

and

where the method, when calculating the timing difference value, includes;

calculating the timing difference value by subtracting one of the timing offset values from the other.

4. The method of claim 1, where the reference timing difference values are respectfully associated with one or more femto cells located at least partially within the macro cell, and where the method further comprises:

identifying the macro cell with which the wireless communication unit can communicate; and

comparing the timing difference value to reference timing difference values respectfully associated with the one or more femto cells located at least partially within the macro cell.

5. The method of claim 1, where identifying the femto cell includes:

identifying the femto cell by identifying a reference timing difference value, of the reference timing difference values, closest to the timing difference value.

6. The method of claim 1, where determining the second observed timing difference includes:

determining the second observed timing difference based on the macro cell having a strongest signal strength for the wireless communication unit.

7. The method of claim 1, further comprising:

calculating at least one other timing difference value based on the first observed timing difference and at least one other observed timing difference observed for communications between the wireless communication unit and at least one other macro cell indicated as having a signal strength above a threshold value for the wireless communication unit.

8. The method of claim 1, further comprising:

receiving an indication from the wireless communication unit of a presence of the femto cell,

where the femto cell is identified based on the indication from the wireless communication unit of the presence of the femto cell.

9. The method for claim 1, further comprising:

receiving a measurement report from the wireless communication unit,

the measurement report comprising observed timing data for at least one femto cell using a femto cell primary scrambling code,

where the femto cell is identified based on the measurement report.

10. The method of claim 1, where the wireless communication unit uses a geo-location subsystem to identify a current location;

and

the current location is stored together with data indicating the first observed timing difference measured at the current location.

11. The method of claim 1, further comprising:

setting a geographical location of the femto cell as a geographical location for the wireless communication unit based on identifying the femto cell.

12. The method of claim 1, further comprising:

handing in an on-going call from the wireless communication unit to the femto cell based on identifying the femto cell.

13. A network device comprising:

one or more processors to;

determine a first observed timing difference observed for communications between a wireless communication unit and a femto cell associated with a macro cell;

determine a second observed timing difference observed for communications between the wireless communication unit and the macro cell;

calculate a timing difference value based on subtracting one of the first observed timing difference or the second observed timing difference from the other of the first observed timing difference or the second observed timing difference;

compare the timing difference value to reference timing difference values,

each reference timing difference value being associated with a particular femto cell of a plurality of femto cells associated with the macro cell; and

identify the femto cell, of the plurality of femto cells, based on comparing the timing difference value to a reference timing difference value, of the reference timing difference values, associated with the femto cell,

the timing difference value being indicative of the femto cell, and

the reference timing difference value being based on mapped data created from data previously obtained by multiple wireless communication units.

14. The network device of claim 13, where the one or more processors are further to:

set a location of the femto cell as a geographical location for the wireless communication unit.

15. The network device of claim 14, where the one or more processors are further to:

access a network configuration file,

the network configuration file comprising latitude and longitude data for the femto cell.

16. The network device of claim 13, where the one or more processors are further to:

hand-in an on-going call from the macro cell to the femto cell based on identifying the femto cell.

17. The network device of claim 16, where the one or more processors are further to:

access a femto cell configuration file,

the femto cell configuration file comprising information identifying femto cells, including at least one of femto cell names or femto cell labels.

18. One or more non-transitory computer-readable media storing instructions, the instructions comprising:

one or more instructions that, when executed by a processor, cause the processor to;

determine a first observed timing difference observed for communications between a wireless communication unit and a femto cell associated with a macro cell;

determine a second observed timing difference observed for communications between the wireless communication unit and the macro cell;

calculate a timing difference value based on subtracting one of the first observed timing difference or the second observed timing difference from the other of the first observed timing difference or the second observed timing difference;

compare the timing difference value to reference timing difference values,

each reference timing difference value being associated with a particular femto cell of a plurality of femto cells associated with the macro cell; and

identify the femto cell, of the plurality of femto cells, based on comparing the timing difference value to a reference timing difference value, of the reference timing difference values, associated with the femto cell,

the timing difference value being indicative of the femto cell, and

the reference timing difference value being based on mapped data created from data previously obtained by multiple wireless communication units.

19. The one or more non-transitory computer-readable media of claim 18, where the first observed timing difference comprises a timing offset value for the femto cell and the second observed timing difference comprises a timing offset value for the macro cell.

20. The one or more non-transitory computer-readable media of claim 18, where the femto cell is within the macro cell.