Efficient gap allocation for cell measurements in asynchronous communication networks

• US 20060223557A1
• Filed: 04/04/2005
• Published: 10/05/2006
• Est. Priority Date: 04/04/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Manohar, Bollapragada Venkata Janaki
• Granted Patent: US 7,702,343 B2
• Time in Patent Office: Days
• US Class Current: 455/502
• CPC Class Codes: H04W 36/0088 Scheduling hand-off measurements
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

Techniques for allocating transmission gaps and making cell measurements in asynchronous communication networks are described. A terminal establishes communication with a first communication network (e.g., a W-CDMA network), receives an initial allocation of transmission gaps for making cell measurements, and makes measurements for cells in a second communication network (e.g., a GSM network) during the allocated transmission gaps. The terminal determines the timing of at least one cell in the second network, which is asynchronous with the first network, and sends the cell timing to the first network. The terminal then receives a new allocation of transmission gaps for making cell measurements. The locations of the transmission gaps in the new allocation are determined based on the cell timing reported by the terminal. The terminal makes measurements for the at least one cell in the second network during the transmission gaps in the new allocation.

Claims

1. A method of making cell measurements, comprising:

establishing communication with a first communication network;

determining timing of at least one cell in a second communication network that is asynchronous with the first communication network;

sending the timing of the at least one cell to the first communication network; and

receiving from the first communication network transmission gaps for making cell measurements, wherein locations of the transmission gaps are determined based on the timing of the at least one cell in the second communication network.

2. The method of claim 1, wherein the sending the timing of the at least one cell to the first communication network comprises

sending the timing of the at least one cell to the first communication network during establishment of communication with the first communication network.

3. The method of claim 2, wherein the timing of the at least one cell is determined based on measurements made for the at least one cell prior to the establishment of communication with the first communication network.

4. The method of claim 1, further comprising:

receiving from the first communication network an initial allocation of transmission gaps for making cell measurements; and

making measurements for cells in the second communication network during the transmission gaps in the initial allocation to determine the timing of the at least one cell in the second communication network.

5. The method of claim 1, further comprising:

making measurements for the at least one cell in the second communication network during the transmission gaps received from the first communication network.

6. The method of claim 5, further comprising:

determining updated timing of the at least one cell based on the measurements made during the transmission gaps received from the first communication network; and

sending to the first communication network a measurement report with the updated timing of the at least one cell.

7. The method of claim 1, wherein the transmission gaps received from the first communication network are time aligned with synchronization bursts to be measured for the at least one cell in the second communication network.

8. The method of claim 1, wherein the timing of each of the at least one cell in the second communication network is given by a time difference between a reference time for the cell and a reference time for the first communication network.

9. An apparatus comprising:

a controller operative to establish communication with a first communication network and to determine timing of at least one cell in a second communication network that is asynchronous with the first communication network;

a transmitter operative to send the timing of the at least one cell to the first communication network; and

a receiver operative to receive from the first communication network transmission gaps for making cell measurements, wherein locations of the transmission gaps are determined based on the timing of the at least one cell in the second communication network.

10. The apparatus of claim 9, wherein the receiver is operative to receive from the first communication network an initial allocation of transmission gaps for making cell measurements, and wherein the controller is operative to initiate measurements for cells in the second communication network during the transmission gaps in the initial allocation and to determine the timing of the at least one cell in the second communication network based on the measurements.

11. An apparatus comprising:

means for establishing communication with a first communication network;

means for determining timing of at least one cell in a second communication network that is asynchronous with the first communication network;

means for sending the timing of the at least one cell to the first communication network; and

means for receiving from the first communication network transmission gaps for making cell measurements, wherein locations of the transmission gaps are determined based on the timing of the at least one cell in the second communication network.

12. The apparatus of claim 11, wherein the means for sending the timing of the at least one cell to the first communication network comprises

means for sending the timing of the at least one cell to the first communication network during establishment of communication with the first communication network.

13. The apparatus of claim 11, further comprising:

means for receiving from the first communication network an initial allocation of transmission gaps for making cell measurements; and

means for making measurements for cells in the second communication network during the transmission gaps in the initial allocation to determine the timing of the at least one cell in the second communication network.

14. A method of making cell measurements, comprising:

determining timing of at least one Global System for Mobile Communications (GSM) cell in a GSM network;

sending the timing of the at least one GSM cell to a Wideband Code Division Multiple Access (W-CDMA) network; and

receiving from the W-CDMA network at least one transmission gap pattern sequence for making cell measurements, wherein locations of transmission gaps in the at least one transmission gap pattern sequence are determined based on the timing of the at least one GSM cell.

15. The method of claim 14, wherein the sending the timing of the at least one GSM cell to the W-CDMA network comprises

sending the timing of the at least one GSM cell to the W-CDMA network during establishment of communication with the W-CDMA network.

16. The method of claim 14, further comprising:

receiving from the W-CDMA network at least one initial transmission gap pattern sequence for making cell measurements; and

making cell measurements during transmission gaps in the at least one initial transmission gap pattern sequence to determine the timing of the at least one GSM cell.

17. The method of claim 14, wherein the locations of the transmission gaps in the at least one transmission gap pattern sequence are time aligned with synchronization channel (SCH) bursts transmitted by the at least one GSM cell.

18. The method of claim 14, wherein the timing of each GSM cell comprises a connection frame number (CFN) for a radio frame with a transmission gap, a TDMA frame number for a synchronization channel (SCH) burst, and a time offset between the radio frame and the SCH burst.

19. The method of claim 14, wherein the timing of each GSM cell comprises a system frame number (SFN) for a radio frame with a transmission gap, a TDMA frame number for a synchronization channel (SCH) burst, and a time offset between the radio frame and the SCH burst.

20. A method of supporting cell measurements, comprising:

receiving, at a first communication network from a terminal, timing of at least one cell in a second communication network that is asynchronous with the first communication network;

allocating the terminal with transmission gaps determined based on the timing of the at least one cell in the second communication network; and

sending the transmission gaps from the first communication network to the terminal.

21. The method of claim 20, further comprising:

establishing communication between the first communication network and the terminal, and wherein the timing of the at least one cell in the second communication network is received during the establishment of communication.

22. The method of claim 20, further comprising:

sending an initial allocation of transmission gaps from the first communication network to the terminal, and wherein the timing of the at least one cell in the second communication network is determined based on cell measurements made during the transmission gaps in the initial allocation.

23. The method of claim 20, wherein the transmission gaps are time aligned with synchronization bursts to be measured for the at least one cell in the second communication network.

24. The method of claim 20, wherein the terminal is allocated a particular number of transmission gaps determined based on the number of cells whose timing is received from the terminal.

25. An apparatus comprising:

means for receiving, at a first communication network from a terminal, timing of at least one cell in a second communication network that is asynchronous with the first communication network;

means for allocating the terminal with transmission gaps determined based on the timing of the at least one cell in the second communication network; and

means for sending the transmission gaps from the first communication network to the terminal.

26. The apparatus of claim 25, further comprising:

means for establishing communication between the first communication network and the terminal, and wherein the timing of the at least one cell in the second communication network is received during the establishment of communication.

27. The apparatus of claim 25, further comprising:

means for sending an initial allocation of transmission gaps from the first communication network to the terminal, and wherein the timing of the at least one cell in the second communication network is determined based on cell measurements made during the transmission gaps in the initial allocation.