Pilot reference transmission for a wireless communication system

• US 9,124,344 B2
• Filed: 09/01/2010
• Issued: 09/01/2015
• Est. Priority Date: 11/03/1997
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Padovani, Roberto, Black, Peter John, Sindhushayana, Nagabhushana T.
• Primary Examiner(s): Abelson, Ronald B
• Application Number:
  US12/874,156
• Publication Number:
  US 20100323748A1
• Time in Patent Office: 1,826 Days
• Field of Search: 370/503, 370/509, 370/510, 370/516, 370/519, 370/520
• US Class Current: 1/1
• 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;

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 common system time reference used by each of the plurality of access points and transmitted at a same predetermined time interval during which all of the access points transmit a pilot burst such that at least respective portions of the pilot bursts overlap in time; and

a processor configured to determine link conditions based on the pilot references, to determine an access point having a highest signal quality based on the link conditions, and to determine a highest supported data rate for the access point having the highest signal quality.

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. The method of claim 1, further comprising:

estimating a signal strength for a first pilot reference based on at least one pilot burst associated with the first pilot reference; and

estimating a maximum interference power for the first pilot reference caused by a second pilot reference.

8. The method of claim 7, further comprising:

estimating a worst case carrier-to-interference (C/I) ratio for the first pilot reference.

9. An access terminal, comprising:

means for receiving a plurality of pilot references transmitted from a plurality of access points, the pilot references from each access point being transmitted in pilot bursts that are synchronized with a common time reference used by each of the plurality of access points and transmitted at a same predetermined time interval during which all of the access points transmit a pilot burst such that at least respective portions of the pilot bursts overlap in time;

means for determining link conditions based on the pilot references;

means for determining an access point having a highest signal quality based on the link conditions; and

means for determining a highest supported data rate for the access point having the highest signal quality.

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

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

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

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

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

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

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

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

14. The access terminal according to claim 13, further comprising:

means for decovering the samples with an orthogonal code used for one of the pilot references at a selected access point.

15. The access terminal according to claim 14, wherein the pilot bursts are aligned in time at the time of transmission.

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

receiving a plurality of pilot references transmitted from a plurality of access points, the pilot references from each access point being transmitted in pilot bursts that are synchronized with a common time reference used by each of the plurality of access points and transmitted at a same predetermined time interval during which all of the access points transmit a pilot burst such that at least respective portions of the pilot bursts overlap in time;

determining link conditions based on the pilot references;

determining an access point having a highest signal quality based on the link conditions; and

determining a highest supported data rate for the access point having the highest signal quality.

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

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

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

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

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

determining a highest data rate supported by the access point.

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

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

21. The method for processing a pilot reference according to claim 20, further comprising:

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

22. The method for processing a pilot reference according to claim 21, wherein the pilot bursts are aligned in time at the time of transmission.