SYSTEM AND METHOD TO LOCATE FEMTO CELLS WITH PASSIVE ASSISTANCE FROM A MACRO CELLULAR WIRELESS NETWORK

• US 20090098873A1
• Filed: 10/09/2008
• Published: 04/16/2009
• Est. Priority Date: 10/12/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gogic, Aleksandar M.
• Granted Patent: US 9,137,745 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04J 11/0069 Cell search, i.e. determining cell identity [cell-ID] design of multiplexing codes H04J13/00; processing access restriction or access information H04W48/16; discovery of network devices for network data management H04W8/005; sounding signals for channel estimation H04L25/0226; structure of reference signals in multicarrier modulation systems H04L27/2613; frame, time or carrier synchronisation in multicarrier modulation systems H04L27/2655
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A system, method and computer product for a mobile station to locate a femto cell, the method comprising: (a) storing in a database information to locate at least one femto cell; (b) receiving, from at least one macro cell, location information of the UE; (c) searching within the database to determine if the UE is in a general proximity of at least one femto cell; (d) if so, accessing the femto cell using the database information corresponding to the femto cell.

Claims

1. A method for a user'"'"'s equipment (UE) to locate a femto cell, the method comprising:

storing in a database information to locate at least one femto cell;

receiving, from at least one macro cell, location information of the UE;

searching within the database to determine if the UE is in a general proximity of at least one femto cell; and

if so, accessing the femto cell using the database information corresponding to the femto cell.

2. The method of claim 1, further comprising:

searching the database for match, wherein a system ID database entry matches the system ID of the macro system around the femto cell, a network ID database entry matches the network ID of the macro system around the femto cell, a base ID database entry matches the base ID of the macro cell, base latitude matches the latitude of the macro cell and base longitude matches the longitude of the macro cell;

if there is match, tuning the UE to a femto cell frequency, F_F;

taking a sample segment of CDMA signal;

conducting pilot search for a pilot PN Offset; and

if there is no match, tuning the UE to a macro cell frequency, F_M.

3. The method of claim 2, further comprising:

searching the database for the pilot PN Offset with sufficient Ec/I₀;

if the pilot PN Offset of sufficient Ec/I₀ is found, performing by the UE idle Handoff (HO) for the femto cell;

if no pilot PN Offset of sufficient Ec/I₀ is found, tuning the UE to the macro cell frequency F_M.

4. The method of claim 3, further comprising:

demodulating by the UE femto cell paging channel;

getting System Parameters Message (SPM) of the femto cell; and

registering the UE on the femto cell.

5. The method of claim 4, wherein demodulating process further comprising:

confirming parameters by the UE system ID, network ID and base ID;

matching with system ID for the femto cell, with the network ID for the femto cell, and base ID broadcast in the femto cell SPM; and

if confirmation fails, attempting to register on the femto cell to determine if it is allowed to access it.

6. A user'"'"'s equipment (UE) comprising:

a database of femto cells acquired by the UE, individualized for the UE and stored on the UE;

wherein a database information includes for each femto cell—

carrier frequency, location, list of CDMA Pilots offsets with Ec/I₀ above a given threshold, system ID for the femto cell, network ID for the femto cell and base ID broadcast for the femto cell;

wherein the UE searches the database to determine if it is in a general proximity of at least one femto cell;

if so, the UE accesses the femto cell using the database information corresponding to the femto cell.

7. The user'"'"'s equipment (UE) of claim 6, wherein the femto search is only conducted if there is a match in the database.

8. The user'"'"'s equipment (UE) of claim 7, wherein the database match is when a system ID matches the system ID of the macro system around the femto cell, a network ID matches the network ID of the macro system around the femto cell, a base ID matches the base ID of the macro cell, base latitude matches the latitude of the macro cell and base longitude matches the longitude of the macro cell

9. The user'"'"'s equipment (UE) of claim 8, wherein if there is a database match, the UE tunes to a femto cell frequency F_F.

10. The user'"'"'s equipment (UE) of claim 8, wherein if there is no a database match, the UE tunes to a macro cell frequency F_M.

11. A computer-program product, comprising:

computer-readable medium comprising codes for causing a computer to;

store in a database information to locate at least one femto cell;

receive, from at least one macro cell, location information of the UE;

search within the database to determine if the UE is in a general proximity of at least one femto cell; and

if so, access the femto cell using the database information corresponding to the femto cell.

12. The computer-program product of claim 11, further comprising codes for causing a computer to:

search the database for match, wherein a system ID database entry matches the system ID of the macro system around the femto cell, a network ID database entry matches the network ID of the macro system around the femto cell, a base ID database entry matches the base ID of the macro cell, base latitude matches the latitude of the macro cell and base longitude matches the longitude of the macro cell;

if there is match, tune the UE to a femto cell frequency, F_F;

take a sample segment of CDMA signal;

conduct pilot search for a pilot PN Offset; and

if there is no match, tuning the UE to a macro cell frequency, F_M.

13. The computer-program product of claim 11, further comprising codes for causing a computer to:

search the database for the pilot PN Offset with sufficient Ec/I₀;

if the pilot PN Offset of sufficient Ec/I₀ is found, perform by the UE idle Handoff (HO) for the femto cell;

if no pilot PN Offset of sufficient Ec/I₀ is found, tune the UE to the macro cell frequency F_M.

14. The computer-program product of claim 11, further comprising codes for causing a computer to:

demodulate by the UE femto cell paging channel;

get System Parameters Message (SPM) of the femto cell; and

register the UE on the femto cell.

15. The computer-program product of claim 14, further comprising codes for causing a computer to:

confirm parameters by the UE system ID, network ID and base ID;

match with system ID for the femto cell, with the network ID for the femto cell, and base ID broadcast in the femto cell SPM ; and

if confirmation fails, attempt to register on the femto cell to determine if it is allowed to access it.

16. An apparatus to locate a femto cell, comprising:

means for storing in a database information to locate at least one femto cell;

means for receiving, from at least one macro cell, location information of the UE;

means for searching within the database to determine if the UE is in a general proximity of at least one femto cell; and

if so, means for accessing the femto cell using the database information corresponding to the femto cell.

17. The apparatus of claim 16, further comprising:

means for searching the database for match, wherein a system ID database entry matches the system ID of the macro system around the femto cell, a network ID database entry matches the network ID of the macro system around the femto cell, a base ID database entry matches the base ID of the macro cell, base latitude matches the latitude of the macro cell and base longitude matches the longitude of the macro cell;

if there is match, tuning the UE to a femto cell frequency, F_F;

taking a sample segment of CDMA signal;

conducting pilot search for a pilot PN Offset; and

if there is no match, tuning the UE to a macro cell frequency, F_M.

18. The apparatus of claim 17, further comprising:

means for searching the database for the pilot PN Offset with sufficient E_C/I₀;

if the pilot PN Offset of sufficient E_C/I₀ is found, means for performing by the UE idle Handoff (HO) for the femto cell;

if no pilot PN Offset of sufficient E_C/I₀ is found, means for tuning the UE to the macro cell frequency F_M.

19. The apparatus of claim 18, further comprising:

means for demodulating by the UE femto cell paging channel;

means for getting System Parameters Message (SPM) of the femto cell; and

means for registering the UE on the femto cell.

20. The apparatus of claim 19, wherein means for demodulating further comprising:

means for confirming parameters by the UE system ID, network ID and base ID;

means for matching with system ID for the femto cell, with the network ID for the femto cell, and base ID broadcast in the femto cell SPM; and

if confirmation fails, means for attempting to register on the femto cell to determine if it is allowed to access it.

21. A method for a user'"'"'s equipment (UE) to locate a femto cell, the method comprising:

determining by the UE if it is in a low mobility status, wherein a degree of mobility can be evaluated by estimating total pilot phase excursions over a period of time;

tuning to a frequency where femto cells are deployed;

taking a signal sample;

conducting a search for all Pilot PN offsets reserved to femto cell use;

finding the femto cell;

determining by the UE if the femto cell is authorized to use;

if so, registering the UE on the femto cell; and

if not, returning to monitor a macro system.

22. The method of claim 21, wherein the UE uses pilot phase deviations of a plurality of macro cells to evaluate its state of mobility.

23. The method of claim 21, wherein the UE searches for pilots in its neighbor list from the macro cells, gets the raw information about the pilot phases, based on which it determines its mobility state.

24. The method of claim 21, wherein the UE takes samples without loosing pages on the macro system that the UE monitors.

25. The method of claim 24, wherein the samples taken for targeted search can be reused to find new femto cells.

26. An apparatus to locate a femto cell, comprising:

means for determining by the UE if it is in a low mobility status, wherein a degree of mobility can be evaluated by estimating total pilot phase excursions over a period of time;

means for tuning to a frequency where femto cells are deployed;

means for taking a signal sample;

means for conducting a search for all Pilot PN offsets reserved to femto cell use;

finding the femto cell;

means for determining by the UE if the femto cell is authorized to use;

if so, registering the UE on the femto cell; and

if not, returning to monitor a macro system.

27. The apparatus of claim 26, wherein the UE uses pilot phase deviations of a plurality of macro cells to evaluate its state of mobility.

28. The apparatus of claim 26, wherein the UE searches for pilots in its neighbor list from the macro cells, gets the raw information about the pilot phases, based on which it determines its mobility state.

29. The apparatus of claim 26, wherein the UE takes samples without loosing pages on the macro system that the UE monitors.

30. The apparatus of claim 26, wherein the samples taken for targeted search can be reused to find new femto cells.

31. A computer-program product, comprising:

computer-readable medium comprising codes for causing a computer to;

determine by the UE if it is in a low mobility status, wherein a degree of mobility can be evaluated by estimating total pilot phase excursions over a period of time;

tune to a frequency where femto cells are deployed;

take a signal sample;

conduct a search for all Pilot PN offsets reserved to femto cell use;

find the femto cell;

determine by the UE if the femto cell is authorized to use;

if so, registering the UE on the femto cell; and

if not, returning to monitor a macro system.

32. The computer-program product of claim 31, wherein the UE uses pilot phase deviations of a plurality of macro cells to evaluate its state of mobility.

33. The computer-program product of claim 31, further comprising codes for causing a computer to:

search for pilots in its neighbor list from the macro cells, get the raw information about the pilot phases, based on which it determines its mobility state.

34. The computer-program product of claim 31, further comprising codes for causing a computer to take samples without loosing pages on the macro system that the UE monitors.

35. The computer-program product of claim 31, further comprising codes for causing a computer to take sample for targeted search for reuse to find new femto cells.

36. A user equipment (UE) comprising:

processor that determines its low mobility status, wherein a degree of mobility can be evaluated by estimating total pilot phase excursions over a period of time;

receiver that tunes to a frequency where femto cells are deployed;

said processor takes a signal sample, conducts a search for all Pilot PN offsets reserved to femto cell use, finds the femto cell, determines if the femto cell is authorized to use,

if so, registers itself on the femto cell; and

if not, returns to monitor a macro system.

37. The user equipment (UE) of claim 36, wherein the UE uses pilot phase deviations of a plurality of macro cells to evaluate its state of mobility.

38. The user equipment (UE) of claim 36, wherein the UE searches for pilots in its neighbor list from the macro cells, gets the raw information about the pilot phases, based on which it determines its mobility state.

39. The user equipment (UE) of claim 36, wherein the UE takes samples without loosing pages on the macro system that the UE monitors.

40. The user equipment (UE) of claim 36, wherein the samples taken for targeted search can be reused to find new femto cells.