PILOT REFERENCE TRANSMISSION FOR A WIRELESS COMMUNICATION SYSTEM

• US 20100323748A1
• Filed: 09/01/2010
• Published: 12/23/2010
• Est. Priority Date: 11/03/1997
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Black, Peter J., Padovani, Roberto, Sindhushayana, Nagabhushana T.
• Granted Patent: US 9,124,344 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04B 7/2687 Inter base stations synchronisation
• CPC Class Codes: H04J 3/0644 External master-clock
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels

Abstract

A pilot reference transmission scheme well suited for high data rate wireless communication systems is disclosed. To maximize the amount of interference from transmissions from neighboring transmission sources (e.g., access points or base stations) during the pilot interval, and hence minimize the amount of interference from non-transmitting sources during the data intervals, the pilot references are transmitted in bursts at predetermined time intervals, and the pilot bursts from the access points are synchronized. This results in maximum interference contributions from non-transmitting neighboring access points, facilitating reliable estimation of worst case carrier-to-interference (C/I), and further allows the receiving devices (e.g., access terminals) to easily recognize the bursts as pilot reference. In one embodiment, each access point transmits the pilot bursts at or near its maximum transmit power level and no user-specific data is transmitted during the pilot bursts.

Claims

1. An access terminal for use in a wireless communication system, comprising:

an RF module configured to receive a modulated signal over a wireless communication link and to condition the received signal to generate a conditioned signal; and

a modem block coupled to the RF module and configured to process the conditioned signal to recover a plurality of pilot references transmitted from a plurality of access points, wherein the pilot reference from each access point is transmitted in pilot bursts that are synchronized with a system time reference, and wherein the pilot bursts from the plurality of access points are aligned in time at the time of transmission.

2. The access terminal according to claim 1, wherein the modem block is configured to generate samples from the conditioned signal and to despread the samples with a pseudo-noise (PN) sequence at a particular offset for each of the plurality of access points.

3. The access terminal according to claim 1, wherein the pilot reference from each said access point is received at a maximum transmit power level.

4. The access terminal according to claim 1, wherein the modem block is further configured to:

correlate received samples with the pilot data pattern for the pilot reference being recovered.

5. The access terminal according to claim 4, wherein the modem block is further configured to:

despread the samples with a same PN sequence at a same time offset.

6. The access terminal according to claim 5, wherein the modem block is further configured to:

decover the samples with a same orthogonal code used for the pilot reference at the selected access point.

7. An access terminal, comprising:

means for receiving a pilot reference transmitted in pilot bursts that are synchronized with a time reference; and

means for determining a link condition based on the pilot reference.

8. The access terminal according to claim 7, further comprising:

means for determining an access point having a best signal quality based at least on the received pilot reference.

9. The access terminal according to claim 7, further comprising:

means for correlating received samples with a pilot data pattern for the pilot reference being recovered.

10. The access terminal according to claim 8, further comprising:

means for determining a highest data rate supported by the access point.

11. The access terminal according to claim 9, further comprising:

means for despreading the samples with a same PN sequence at a same time offset.

12. The access terminal according to claim 11, further comprising:

means for decovering the samples with a same orthogonal code used for the pilot reference at a selected access point.

13. The access terminal according to claim 12, wherein the pilot bursts are aligned in time at the time of transmission.

14. A method for processing a pilot reference, comprising:

receiving a pilot reference transmitted in pilot bursts that are synchronized with a time reference; and

determining a link condition based on the pilot reference.

15. The method for processing a pilot reference according to claim 14, further comprising:

determining an access point having a best signal quality based at least on the received pilot reference.

16. The method for processing a pilot reference according to claim 14, further comprising:

correlating received samples with a pilot data pattern for the pilot reference being recovered.

17. The method for processing a pilot reference according to claim 15, further comprising:

determining a highest data rate supported by the access point.

18. The method for processing a pilot reference according to claim 16, further comprising:

despreading the samples with a same PN sequence at a same time offset.

19. The method for processing a pilot reference according to claim 18, further comprising:

decovering samples with a same orthogonal code used for the pilot reference at a selected access point.

20. The method for processing a pilot reference according to claim 19, wherein the pilot bursts are aligned in time at the time of transmission.