System and method for extending neighboring cell search window

• US 20040152478A1
• Filed: 01/31/2003
• Published: 08/05/2004
• Est. Priority Date: 01/31/2003
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Ruohonen, Jari J., Savela, Vesa, Bysted, Tommy
• Granted Patent: US 7,633,927 B2
• Time in Patent Office: Days
• US Class Current: 455/502
• CPC Class Codes: H04J 3/0605 Special codes used as synchronising signal
• CPC Class Codes: H04W 36/0088 Scheduling hand-off measurements
• CPC Class Codes: H04W 72/1268 of uplink data flows

Abstract

A system and method for accommodating mobile station synchronization to neighbor cells in a mobile communication system. At least one available frame is utilized as a search window in an uplink data transfer multiframe for receiving neighboring cell synchronization information. At least one transmit time slot in a frame adjacent to the available frame in the uplink data transfer multiframe is surrendered to extend the search window. The neighboring cell synchronization information may then be contiguously received via the extended search window.

Claims

1. A method of accommodating mobile station synchronization to one or more neighbor cells in a mobile communication system, wherein the mobile communication system includes base transceiver stations (BTS) each defining a cell and at least one mobile station (MS) capable of communicating with at least one BTS, the method comprising:

utilizing at least one available frame as a search window in an uplink data transfer multiframe for receiving neighboring cell synchronization information;

surrendering at least one transmit time slot in a frame adjacent to the available frame in the uplink data transfer multiframe to extend the search window; and

receiving the neighboring cell synchronization information in the extended search window.

2. The method of claim 1, wherein surrendering at least one transmit time slot in a frame adjacent to the available frame comprises surrendering at least one transmit time slot in a frame immediately preceding the available frame.

3. The method of claim 2, wherein surrendering at least one transmit time slot in a frame immediately preceding the available frame comprises surrendering at least one transmit time slot from the immediately preceding frame that is closest to the available frame to provide contiguous time slots in the extended search window.

4. The method of claim 2, further comprising maintaining an end boundary of the available frame to prevent disturbing a successive frame contiguous with the available frame.

5. The method of claim 1, wherein surrendering at least one transmit time slot comprises surrendering as many transmit time slots as necessary to provide the extended search window at a size capable of accommodating all of the neighboring cell synchronization information.

6. The method of claim 1, further comprising surrendering at least one receive time slot in the frame adjacent to the available frame and opposite the frame in which the at least one transmit time slot was surrendered, to further extend the search window.

7. The method of claim 1, wherein the neighboring cell synchronization information comprises a Frequency Correction Burst (FB) associated with a Frequency Correction Channel (FCCH).

8. The method of claim 7, wherein the neighboring cell synchronization information further comprises at least one Synchronization Burst (SB) associated with a Synchronization Channel (SCH).

9. The method of claim 7, further comprising receiving at least one Synchronization Burst (SB) associated with a Synchronization Channel (SCH) after the FCCH has been received.

10. The method of claim 1, wherein utilizing at least one available frame as a search window comprises utilizing at least one defined Idle Frame in the uplink data transfer multiframe.

11. The method of claim 1, wherein utilizing at least one available frame as a search window comprises utilizing any one or more frames in the uplink data transfer multiframe having a plurality of contiguous available time slots.

12. The method of claim 1, wherein the MS is associated with an MS multislot class which accommodates fewer consecutive available time slots than are available in the search window prior to extension.

13. The method of claim 12, wherein surrendering at least one transmit time slot comprises surrendering a number of transmit time slots required to accommodate the MS multislot class.

14. The method of claim 13, wherein surrendering a number of transmit time slots required to accommodate the MS multislot class comprises surrendering a number of transmit time slots required to provide ten consecutive time slots, inclusive of a time required for MS radio frequency circuitry to change between a data transfer channel and a synchronization channel.

15. The method of claim 1, further comprising at least partially synchronizing the MS with a neighboring cell corresponding to the synchronization information retrieved via the extended search window.

16. The method of claim 1, further comprising repeating a search for the neighboring cell synchronization information in a plurality of the available frames to facilitate the receiving of the neighboring cell synchronization information in the extended search window of at least one of the plurality of available frames.

17. The method of claim 16, wherein the synchronization information comprises a Frequency Correction Burst (FB) associated with a Frequency Correction Channel (FCCH), and further comprising determining a location of a Synchronization Channel (SCH) based on a location of the FCCH and receiving the SCH in an available frame at least one multiframe after the FCCH using a timing offset relative to a timing offset of the FCCH.

18. The method of claim 1, wherein the MS comprises an MS type where transmit and receive operations are not simultaneously performed.

19. The method of claim 18, wherein the MS type comprises a type-1 MS.

20. A Mobile Station (MS) operable in a wireless network comprising a plurality of cells each defined by a Base Transceiver Station (BTS), the MS comprising:

a transceiver to communicate with a plurality of neighboring BTSs to receive synchronization channels transmitted by the neighboring BTSs; and

a processing module configured to extend a search window in an uplink data transfer multiframe by sacrificing one or more transmit time slots in a frame of the uplink data transfer multiframe adjacent to an available frame where receipt of synchronization channels are expected.

21. The MS of claim 20, wherein the processing module comprises a processor device operating under the direction of one or more program modules having instructions to direct the processor device to sacrifice the one or more transmit time slots in the frame adjacent to the available frame.

22. The MS of claim 20, wherein the processing module comprises a Digital Signal Processor (DSP) operating under the direction of one or more program modules having instructions to direct the DSP to sacrifice the one or more transmit time slots in the frame adjacent to the available frame.

23. The MS of claim 20, wherein the available frame comprises a defined Idle Frame in the uplink data transfer multiframe, and wherein the processing module is configured to extend the search window by sacrificing at least one transmit time slot in the frame immediately preceding the defined Idle Frame.

24. A system for synchronizing communications in a mobile communication system, comprising:

(a) a plurality of cells each defined by a Base Transceiver Station (BTS);

(b) at least one Mobile Station (MS) for communicating with a plurality of the BTSs neighboring the cell in which the MS is currently operating, wherein the MS comprises;

(i) a transceiver to communicate with the plurality of the neighboring BTSs to receive synchronization channels transmitted by the neighboring BTSs; and

(ii) a processing module configured to extend a search window in an uplink data transfer multiframe by surrendering one or more transmit time slots in a frame of the uplink data transfer multiframe adjacent to an available frame where receipt of synchronization channels are expected.

25. The system of claim 24, wherein the mobile communication system comprises a GSM network.

26. The system of claim 24, wherein the available frame comprises a defined Idle Frame in the uplink data transfer multiframe, and wherein the processing module is configured to extend the search window by sacrificing at least one transmit time slot in the frame immediately preceding the defined Idle Frame.

27. A computer-readable medium having instructions stored thereon which are executable by a computer system for accommodating mobile station synchronization to one or more neighbor cells in a mobile communication system, wherein the mobile communication system includes base transceiver stations (BTS) each defining a cell and at least one mobile station (MS) capable of communicating with at least one BTS, the instructions performing steps comprising:

utilizing at least one available frame as a search window in an uplink data transfer multiframe for receiving neighboring cell synchronization information;

surrendering at least one transmit time slot in a frame adjacent to the available frame in the uplink data transfer multiframe to extend the search window; and

receiving the neighboring cell synchronization information in the extended search window.