TIME SYNCHRONIZATION OF FEMTOCELL

• US 20090092122A1
• Filed: 06/23/2008
• Published: 04/09/2009
• Est. Priority Date: 10/05/2007
• Status: Active Grant

• Current Assignee: IPCOMM LLC, LG Electronics, Inc. (LG Corporation), Via Telecom Co., Ltd.
• Original Assignee: IPCOMM LLC, Via Telecom Inc. (VIA Technologies)
• Inventors: Czaja, Stanislaw, Lee, Anthony, Davis, Mark E.
• Granted Patent: US 8,213,391 B2
• Time in Patent Office: Days
• US Class Current: 370/350
• CPC Class Codes: H04L 7/041 using special codes as synchronising signal
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

Time synchronization of an access point base station. The method may include receiving an assignment message from a service provider comprising a plurality of parameters. The plurality of parameters may include an access point base station frequency assignment, a network identifier, an access point base station identifier, a neighbor list, a PN offset, and/or a scrambling code. The access point base station may then synchronize with the macro base station. Synchronizing may include searching for a strongest macro base station in the neighbor list, synchronizing a long code of the access point base station to the macro base station, estimating a propagation delay between the macro base station and the access point base station, and initializing a state of the access point base station PN code using the propagation delay to provide system time synchronization.

Claims

1. A method for performing time synchronization of an access point base station with a system time of a macro base station, the method comprising:

receiving an assignment message from a service provider, wherein the assignment message comprise a neighbor list; and

synchronizing the access point base station with the macro base station, wherein the synchronizing comprises;

searching for a strongest macro base station in the neighbor list;

synchronizing a long code of the access point base station to the macro base station;

estimating a propagation delay between the macro base station and the access point base station; and

initializing a state of the access point base station PN code using the propagation delay to provide system time synchronization.

2. The method of claim 1, wherein synchronizing the access point base station with the macro base station comprises:

tuning a receiver of the access point base station to a neighbor downlink frequency specified in the neighbor list.

3. The method of claim 1, further comprising:

connecting the access point base station to the service provider, wherein the access point base station provides wireless communication in a local area for one or more access terminals, and wherein the service provider provides wireless communication in a macro area via the macro base station; and

transmitting an activation request message to the service provider;

wherein the connecting step and the transmitting step are performed prior to receiving the assignment message.

4. The method of claim 1, wherein receiving the assignment message and synchronizing the access point base station with the macro base station is performed over an IP connection.

5. The method of claim 1, further comprising:

adjusting a system time of the access point base station one or more times to provide system time synchronization.

6. The method of claim 5, wherein the adjusting step comprises using clock calibration of a clock of the access point base station.

7. The method of claim 5, wherein the adjusting step comprises tracking a carrier frequency of an access terminal or base station and calibrating timing of the access point base station according to the carrier frequency.

8. The method of claim 5, wherein the adjusting step the system time comprises the access point base station synchronizing with the macro base station.

9. The method of claim 5, wherein the adjusting step is performed in response to a message received from the service provider.

10. The method of claim 1, wherein the assignment message further comprises:

an access point base station frequency assignment;

a network identifier;

an access point base station identifier; and

a PN offset.

11. A method for performing time synchronization of an access point base station with a timing of a macro base station, the method comprising:

receiving an assignment message from a service provider, wherein the assignment message comprises a neighbor list; and

synchronizing the access point base station with the macro base station, wherein the synchronizing comprises;

searching for a strongest macro base station in the neighbor list;

performing slot boundary synchronization by processing a PSCH (primary synchronization channel) of the macro base station; and

performing frame boundary synchronization by processing a SSCH (secondary synchronization channel) of the macro base station;

wherein the step of performing the slot boundary synchronization and the step of performing the frame boundary synchronization provides frame synchronization between the access point base station and the macro base station.

12. The method of claim 11, further comprising:

connecting to the service provider, wherein the access point base station provides wireless communication in a local area for one or more access terminals, and wherein the service provider provides wireless communication in a macro area via the macro base station; and

transmitting an activation request message to the service provider;

wherein the connecting step and the transmitting step are performed prior to the step of receiving the assignment message.

13. The method of claim 11, wherein the step of receiving the assignment message and the step of synchronizing the access point base station with the macro base station is performed over an IP connection.

14. The method of claim 11, further comprising:

adjusting the timing of the access point base station one or more times to provide frame synchronization.

15. The method of claim 14, wherein said the step of adjusting the timing comprises the access point base station synchronizing with the macro base station.

16. The method of claim 14, wherein the step of adjusting is performed in response to a message received from the service provider.

17. The method of claim 11, wherein the assignment message further comprises:

an access point base station frequency assignment;

a network identifier;

an access point base station identifier; and

a scrambling code.

18. A femtocell, comprising:

an interface for providing communication with one or more access terminals in a local area and providing communication with a service provider in a macro area via a macro base station;

a processor coupled to the interface;

a memory medium coupled to the processor, wherein the memory medium comprises program instructions executable to;

receive an assignment message from the service provider, wherein the assignment message comprises a neighbor list; and

synchronize with the macro base station, wherein the synchronizing comprises;

searching for a strongest macro base station in the neighbor list;

synchronizing a long code of the access point base station to the macro base station;

estimating a propagation delay of the macro base station; and

initializing a state of the femtocell PN code using the propagation delay to provide system time synchronization.

19. The femtocell of claim 18, wherein the program instructions are further executable to:

adjust the system time of the femtocell one or more times to provide system time synchronization.

20. The femtocell of claim 19, wherein the step of adjusting comprises using clock calibration of a clock of the access point base station.

21. A femtocell, comprising:

an interface for providing communication with one or more access terminals in a local area and providing communication with a service provider in a macro area via a macro base station;

a processor coupled to the interface;

a memory medium coupled to the processor, wherein the memory medium comprises program instructions executable to;

receive an assignment message from the service provider, wherein the assignment message comprise a neighbor list; and

synchronize with the macro base station, wherein the synchronizing comprises;

searching for a strongest macro base station in the neighbor list;

performing slot boundary synchronization by processing a PSCH (primary synchronization channel) of the macro base station; and

performing frame boundary synchronization by processing a SSCH (secondary synchronization channel) of the macro base station;

wherein the step of performing the slot boundary synchronization and the step of performing the frame boundary synchronization provides frame synchronization between the femtocell and the macro base station.

22. The femtocell of claim 21, wherein the program instructions are further executable to:

adjust the system time of the femtocell one or more times to provide system time synchronization.

23. A communication system for providing wireless communication with one or more access terminals, comprising:

a service provider;

a macro base station for providing wireless communication with the one or more access terminals in a macro area; and

an access point base station for providing wireless communication with the one or more access terminals in a local area intersected partially with the macro area, and wherein the access point base station is configured to;

receive an assignment message from the service provider, wherein the assignment message comprises a neighbor list; and

synchronize with the macro base station, wherein the synchronizing comprises;

searching for a strongest macro base station in the neighbor list;

synchronizing a long code of the access point base station to the macro base station;

estimating a propagation delay of the macro base station; and

initializing a state of the femtocell PN code using the propagation delay to provide system time synchronization.

24. A communication system for providing wireless communication with one or more access terminals, comprising:

a service provider;

a macro base station for providing wireless communication with the one or more access terminals in a macro area; and

an access point base station for providing wireless communication with the one or more access terminals in a local area intersected partially with the macro area, and wherein the access point base station is configured to;

receive an assignment message from the service provider, wherein the assignment message comprise a neighbor list; and

synchronize with the macro base station, wherein the synchronizing comprises;

searching for a strongest macro base station in the neighbor list;

performing slot boundary synchronization by processing a PSCH (primary synchronization channel) of the macro base station; and

performing frame boundary synchronization by processing a SSCH (secondary synchronization channel) of the macro base station;

wherein the step of performing the slot boundary synchronization and the step of performing the frame boundary synchronization provides frame synchronization between the femtocell and the macro base station.