Method and apparatus in a CDMA communication system

• US 7,254,118 B1
• Filed: 05/22/2000
• Issued: 08/07/2007
• Est. Priority Date: 05/22/2000
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Grilli, Francesco, Willenegger, Serge, Terasawa, Daisuke
• Primary Examiner(s): Feild; John
• Assistant Examiner(s): MEHRA, INDER P
• Application Number:
  US09/576,063
• Time in Patent Office: 2,633 Days
• Field of Search: 370/320, 370/328, 370/331, 370/335, 370/342, 370/350, 370/441, 370508-512, 370/514, 370518-520, 370/442, 370/503, 455/436, 455/442, 455/502, 455/524, 455/525, 455/517, 455/522
• US Class Current: 370/328
• 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 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 56/0065 using measurement of signal travel time

Abstract

A novel and improved method and apparatus, in a WCDMA communication system (100), for informing a mobile station (101) of a downlink data frame time offset by determining the downlink data frame time offset, and transmitting the downlink data frame time offset via an Active Set Update message transmitted from a cell (102 or 103) to mobile station (101). Once an Active Set Update message is received, the data frame time offset information is provided to a timing block (201) which may determine data frame boundary of each downlink signal. Timing block (201) may then adjust the PN sequence timing corresponding to the downlink signal associated with the data frame time offset such that corresponding data symbols in each data frame are correctly soft combined in a combiner (210).

Claims

1. A method for a soft handoff operation in a CDMA communication system, comprising:

transmitting data frames from a first base station to a mobile station in accordance with a first downlink data frame time offset, wherein said first downlink data frame time offset is measured from a channel frame timing associated with the first base station;

measuring a reception downlink time offset experienced at said mobile station between a first downlink transmission received from said first base station and a second downlink transmission from a second base station;

communicating said measured reception downlink time offset from said mobile station to at least one of said first and second base stations;

determining a second downlink data frame time offset based on said measured reception downlink time offset, wherein said second downlink data frame time offset is measured from a channel frame timing associated with the second base station, wherein said first and second downlink data frame time offsets are in increments of a predetermined number of chips;

communicating said second downlink data frame time offset to said mobile station for said soft handoff operation; and

transmitting data frames from said second base station to said mobile station in accordance with said second downlink data frame time offset, wherein data frames transmitted from said first and second base station carry the same data for said soft handoff operation.

2. The method as recited in claim 1 wherein said communicating said second downlink data frame time offset is by way of communicating an Active Set Update message in said CDMA communication system.

3. The method as recited in claim 1 wherein said communicating said measured reception down time offset is by way of communicating a measurement report message from said mobile station.

4. The method as recited in claim 1 further comprising:

adjusting timing of a time offset adjuster in said mobile station for adjusting data symbols timing according to said first and second downlink data frame time offsets for identifying corresponding data symbols in transmitted data frames from said first and second base stations for said soft handoff operation.

5. The method as recited in claim 4 wherein said soft handoff operation includes soft combining said corresponding data symbols.

6. A method for a soft handoff operation in a CDMA communication system, comprising:

measuring a reception downlink time offset experienced at a mobile station between a first downlink transmission received from a first base station and a second downlink transmission from a second base station;

communicating said measured reception downlink time offset from said mobile station to at least one of said first and second base stations;

receiving data frames from said first base station at said mobile station in accordance with a first downlink data frame time offset, wherein said first downlink data frame time offset is measured from a channel frame timing associated with the first base station;

receiving a second downlink data frame time offset at said mobile station for said soft handoff operation, wherein said second downlink data frame time offset is determined based on said measured reception downlink time offset, and wherein said second downlink data fame time offset is measured from a channel frame timing associated with the second base station, and wherein said first and second downlink data frame time offsets are in increments of a predetermined number of chips; and

receiving data frames from said second base station at said mobile station in accordance with said second downlink data frame time offset, wherein data frames received from said first and second base stations carry the same data for said soft handoff operation.

7. The method as recited in claim 6 wherein said receiving said second downlink data frame time offset at said mobile station for said soft handoff operation is by way of receiving an Active Set Update message.

8. The method as recited in claim 6 wherein said communicating said measured reception time offset is by way of communicating a measurement report message from said mobile station.

9. The method as recited in claim 6 further comprising:

adjusting timing of a time offset adjuster in said mobile station for adjusting reception data symbols timing according to said first and second downlink data frame time offsets for identifying corresponding data symbols in received data frames from said first and second base stations for said soft combining operation.

10. The method as recited in claim 9 wherein said soft handoff operation includes soft combining said corresponding data symbols.

11. An apparatus for a soft handoff operation in a CDMA communication system, comprising:

a transmitter and a receiver, wherein said receiver includes a timing block, a de-spreader, a demodulator and a decoder, configured for performing a set of operations including;

measuring a reception downlink time offset experienced at said receiver between a first downlink transmission received from a first base station and a second downlink transmission from a second base station;

communicating said measured reception downlink time offset from said transmitter to at least one of said first and second base stations;

receiving data frames from said first base station at said receiver in accordance with a first downlink data frame time offset, wherein said first downlink data frame time offset is measured from a channel frame timing associated with the first base station;

receiving a second downlink data frame time offset at said receiver for said soft handoff operation, wherein said second downlink data frame time offset is determined based on said measured reception downlink time offset, and wherein said second downlink data frame time offset is measured from a channel frame timing associated with the second base station, and wherein said first and second downlink data frame time offsets are in increments of a predetermined number of chips; and

receiving data frames from said second base station at said mobile station in accordance with said second downlink data frame time offset, wherein data frames transmitted from said first and second base stations carry the same data for said soft handoff operation.

12. The apparatus as recited in claim 11, wherein said set of operations further comprising:

adjusting timing of a time offset adjuster in said mobile station for adjusting reception data symbols timing according to said first and second downlink data frame time offsets for identifying corresponding data symbols in received data frames from said first and second base stations for said soft combining operation.

13. The apparatus as recited in claim 12, wherein said set of operations further comprising;

soft combining said corresponding data symbols.

14. A method for a soft handoff operation in a CDMA communication system, comprising:

transmitting data frames from a first base station to a mobile station in accordance with a first downlink data frame time offset, wherein said first downlink data frame time offset is measured from a channel frame timing associated with the first base station;

receiving a measured reception downlink time offset from said mobile station at one of said first and second base stations, wherein said measured reception downlink time offset is the reception time offset experienced at said mobile station between a first downlink transmission from said first base station and a second downlink transmission from a second base station;

determining a second downlink time offset based on said measured reception downlink time offset, wherein said second downlink data frame time offset is measured from a channel frame timing associated with the second base station wherein said first and second downlink data frame time offsets are in increments of a predetermined number of chips;

communicating said second downlink data frame time offset to said mobile station for said soft handoff operation; and

transmitting data frames from said second base station to said mobile station in accordance with said second downlink data fame time offset, wherein data frames transmitted from said first and second base station carry the same data for said soft handoff operation.

15. The method as recited in claim 14 wherein said communicating said second downlink data frame time offset is by way of communicating an Active Set Update message in said CDMA communication system.

16. The method as recited in claim 14 wherein said receiving said measured reception downlink time offset is by way of receiving a measurement report message from said mobile station.

17. An apparatus for a soft handoff operation in a CDMA communication system, comprising:

a transmitter, a receiver and associated control apparatus configured for performing a set of operations for said handoff operation, wherein said set of operations includes;

transmitting data frames from a first base station to a mobile station in accordance with a first downlink data frame time offset, wherein said first downlink data fine time offset is measured from a channel frame timing associated with the first base station;

receiving a measured reception downlink time offset from said mobile station at one of said first and second base stations, wherein said measured reception downlink time offset is the reception time offset experienced at said mobile station between a first downlink transmission from said first base station and a second downlink transmission from a second base station;

determining a second downlink time offset based on said measured reception downlink time offset, wherein said second downlink data frame time offset is measured from a channel frame timing associated with the second base station, wherein said first and second downlink data frame time offsets are in increments of a predetermined number of chips;

communicating said second downlink data frame time offset to said mobile station for said soft handoff operation; and

transmitting data fines from said second base station to said mobile station in accordance with said second downlink data frame time offset, wherein data frames transmitted from said first and second base station carry the same data for said soft handoff operation.

18. The apparatus as recited in claim 17 wherein said communicating said second down data frame time offset in said set of operations is by way of communicating an Active Set Update message in said CDMA communication system.

19. The method as recited in claim 17 wherein said receiving said measured reception downlink time offset in said set of operations is by way of receiving a measurement report message from said mobile station.