Method and apparatus for time-aligning transmissions from multiple base stations in a CDMA communication system

• US 7,903,633 B2
• Filed: 08/22/2008
• Issued: 03/08/2011
• Est. Priority Date: 07/09/2001
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wheatley, Charles E. III, Willenegger, Serge D., Grilli, Francesco, Subrahmanya, Parvathanathan
• Primary Examiner(s): Nguyen; Brian D
• Application Number:
  US12/196,489
• Publication Number:
  US 20080310321A1
• Time in Patent Office: 928 Days
• Field of Search: 370/252, 370/335, 370/342, 370/350, 370/503, 370/509, 370/516
• US Class Current: 370/350
• CPC Class Codes: H04B 2201/70702 Intercell-related aspects
• CPC Class Codes: H04B 7/2668 Arrangements for Wireless Code-Division Multiple Access [CDMA] System Synchronisation, for code acquisition H04B1/7075, for code tracking H04B1/7085
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time
• CPC Class Codes: H04W 92/20 between access points

Abstract

Schemes to time-align transmissions from multiple base stations to a terminal. To achieve time-alignment, differences between the arrival times of transmissions from the base stations, as observed at the terminal, are determined and provided to the system and used to adjust the timing at the base stations such that terminal-specific radio frames arrive at the terminal within a particular time window. In one scheme, a time difference between two base stations is partitioned into a frame-level time difference and a chip-level time difference. Whenever requested to perform and report time difference measurements, the terminal measures the chip-level timing for each candidate base station relative to a reference base station. Additionally, the terminal also measures the frame-level timing and includes this information in the time difference measurement only if required. Otherwise, the terminal sets the frame-level part to a predetermined value (e.g., zero).

Claims

1. A method of communications by a communication apparatus with a plurality of base stations, comprising:

receiving a request to provide differences in timing for the plurality of base stations, wherein the differences in timing include the difference of a chip-level timing and the difference of a frame-level timing of at least two of the plurality of base stations;

determining whether the difference of the frame-level timing is needed; and

providing only the difference of the chip-level timing if the difference of the frame-level timing is not needed.

2. The method as in claim 1 wherein the step of determining is based on information as to whether the at least two of the plurality of base stations are operated synchronously or asynchronously.

3. The method as in claim 1 wherein the step of determining is based on indication provided by a communication network.

4. The method as in claim 1 wherein if the difference of the frame-level timing is needed, the method further including determining the difference of the frame-level timing of a predetermined channel of the at least two of the plurality of base stations.

5. The method as in claim 4 wherein the predetermined channel is a broadcast control channel (BCCH).

6. The method as in claim 1 wherein the difference of the chip-level timing is based on the time offsets of the pseudo-noise sequences of the at least two of the plurality of base stations.

7. An apparatus for communications with a plurality of base stations, comprising:

means for receiving a request to provide differences in timing for the plurality of base stations, wherein the differences in timing include the difference of a chip-level timing and the difference of a frame-level timing of at least two of the plurality of base stations;

means for determining whether the difference of the frame-level timing is needed; and

means for providing only the difference of the chip-level timing if the difference of the frame-level timing is not needed.

8. The apparatus as in claim 7 wherein the means for determining determines on information as to whether the at least two of the plurality of base stations are operated synchronously or asynchronously.

9. The apparatus as in claim 7 wherein the means for determining receives indication provided by a communication network.

10. The apparatus as in claim 7 wherein if the difference of the frame-level timing is needed, the means for determining further determines the difference of the frame-level timing of a predetermined channel of the at least two of the plurality of base stations.

11. The apparatus as in claim 10 wherein the predetermined channel is a broadcast control channel (BCCH).

12. The apparatus as in claim 7 wherein the difference of the chip-level timing is based on the time offsets of the pseudo-noise sequences of the at least two of the plurality of base stations.

13. An apparatus of communications with a plurality of base stations, comprising:

a controller;

circuitry coupled to the controller configured to;

receive a request to provide differences in timing for the plurality of base stations, wherein the differences in timing include the difference of a chip-level timing and the difference of a frame-level timing of at least two of the plurality of base stations;

determine whether the difference of the frame-level timing is needed; and

provide only the difference of the chip-level timing if the difference of the frame-level timing is not needed.

14. The apparatus as in claim 13 wherein to determine whether the difference of the frame-level timing is needed is based on information as to whether the at least two of the plurality of base stations are operated synchronously or asynchronously.

15. The apparatus as in claim 13 wherein to determine whether the difference of the frame-level timing is needed is based on indication provided by a communication network.

16. The apparatus as in claim 13 wherein if the difference of the frame-level timing is needed, the circuitry coupled to the controller are further configured to determine the difference of the frame-level timing of a predetermined channel of the at least two of the plurality of base stations.

17. The apparatus as in claim 16 wherein the predetermined channel is a broadcast control channel (BCCH).

18. The apparatus as in claim 13 wherein the difference of the chip-level timing is based on the time offsets of the pseudo-noise sequences of the at least two of the plurality of base stations.