Time synchronization of femtocell

• US 8,213,391 B2
• Filed: 06/23/2008
• Issued: 07/03/2012
• 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, LG Electronics, Inc. (LG Corporation), Via Telecom Inc. (VIA Technologies)
• Inventors: Czaja, Stanislaw, Davis, Mark E., Lee, Anthony, Kim, Sang Gook, Sun, Li-Hsiang
• Primary Examiner(s): Lin, Kenny
• Assistant Examiner(s): Esmaeilian, Majid
• Application Number:
  US12/143,924
• Publication Number:
  US 20090092122A1
• Time in Patent Office: 1,471 Days
• Field of Search: 370/335
• US Class Current: 370/335
• 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 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 the neighbor list comprises a signal strength of the macro base station and the timing of the macro base station; 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 according to the signal strength;

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 to detect scrambling code change on each frame;

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.

2. The method of claim 1, 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.

3. The method of claim 1, 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.

4. The method of claim 1, further comprising:

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

5. The method of claim 4, wherein said the step of adjusting the timing comprises the access point base station synchronizing with the macro base station.

6. The method of claim 4, wherein the step of adjusting is performed in response to a message received from the service provider.

7. 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 scrambling code.

8. 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 the neighbor list comprises a signal strength of the macro base station; and

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

searching for a strongest macro base station in the neighbor list according to the signal strength;

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 to detect scrambling code change on each frame;

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.

9. The femtocell of claim 8, wherein the program instructions are further executable to:

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

10. 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 the neighbor list comprises a signal strength of the macro base station; and

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

searching for a strongest macro base station in the neighbor list according to the signal strength;

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 to detect scrambling code change on each frame;

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.