Method and apparatus for feedback error detection in a wireless communications systems

• US 20030148738A1
• Filed: 01/27/2003
• Published: 08/07/2003
• Est. Priority Date: 02/07/2002
• Status: Active Grant

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Sampath, Ashwin, Das, Arnab, Su, Hsuan-Jung, Khan, Farooq Ullah
• Granted Patent: US 7,116,944 B2
• Time in Patent Office: Days
• US Class Current: 455/67.16
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0654 at the receiver, e.g. antenna verification at mobile station
• CPC Class Codes: H04B 7/0665 Feed forward of transmit weights to the receiver

Abstract

Errors in closed loop transmit diversity (CLTD) feedback signaling may be detected and/or corrected by a mobile station, according to aspects of the present invention, based on signals received from a base station. The mobile station is generally configured to compute antenna weights to be applied at the base station and feed back corresponding antenna control bits to the base station, as in conventional CLTD systems. However, rather than automatically process subsequent transmissions received from the base station as if the base station properly received the antenna control bits and applied the computed antenna weights, the mobile station attempts to determine the antenna weights actually applied at the base station, and uses these determined antenna weights for processing the subsequent transmissions. Accordingly, even if a feedback signaling error occurred, resulting in the base station using the wrong antenna weights, the mobile station may properly process the transmissions. According to some aspects of the present invention, the base station transmits (feeds forward) antenna control bits actually received from the mobile station on a feed forward channel, and the mobile station processes subsequent transmissions using antenna weights generated based on the fed forward antenna control bits.

Claims

1. A method for use in a mobile station, comprising the steps of:

generating antenna control information for use at a base station based on one or more signals received from the base station;

transmitting the antenna control information to the base station;

receiving antenna control information from the base station; and

processing subsequent signals received from the base station according to the antenna control information received from the base station.

2. The method of claim 1, further comprising the step of comparing the generated antenna control information to the antenna control information received from the base station to detect a feedback signaling error.

3. The method of claim 1, wherein said step of generating comprises generating antenna weights to be applied to signals transmitted from the base station.

4. The method of claim 3, wherein the antenna control information comprises a set of bits for use in generating the antenna weights at the base station.

5. The method of claim 4, wherein the set of bits comprises at least two bits for phase control and at least two bits for relative transmit amplitude control.

6. The method of claim 1, wherein said step of generating comprises selecting one of the base station antennas to be used for sending signals from the base station to the mobile station.

7. A method for use in a base station having multiple antennas, comprising the steps of:

receiving antenna control information from a mobile station;

transmitting the received antenna control information to the mobile station; and

transmitting one or more signals to the mobile station in accordance with the received antenna control information.

8. The method of claim 7, wherein said step of transmitting one or more signals to the mobile station in accordance with received antenna control information comprises the steps of:

generating a set of antenna weights based on the antenna control information; and

applying the antenna weights to the one or more signals.

9. The method of claim 7, wherein said step of transmitting one or more signals to the mobile station in accordance with received antenna control information comprises transmitting the one or more signals from a selected one of the multiple antennas specified by the antenna control information.

10. A method for use in a mobile station, comprising the steps of:

generating antenna weights for use at a base station;

transmitting antenna control information indicative of the generated antenna weights to the base station;

receiving one or more signals from the base station;

estimating, based on the one or more signals, antenna weights applied at the base station in transmitting the one or more signals; and

processing the one or more signals according to the estimated antenna weights.

11. The method of claim 10, wherein said step of estimating comprises the step of estimating antenna weights applied at the base station based on pilot signals broadcast by each of the base station antennas.

12. The method of claim 10, further comprising the step of comparing the estimated antenna weights to the generated antenna weights to detect a feedback signaling error.

13. A method for use in a mobile station, comprising the steps of:

selecting one of a plurality of antennas for use in transmitting signals from a base station;

transmitting antenna control information indicative of the selected antenna to the base station;

receiving one or more signals from the base station;

determining which of the base station antennas was used for transmitting the one or more signals from the base station; and

processing subsequently received signals from the base station as if the subsequently received signals were transmitted using the determined base station antenna.

14. The method of claim 13, wherein said step of determining which of the base station antennas was used for transmitting the one or more signals comprises the steps of:

generating a set of processed signals, each processed signal generated by processing the one or more signals as if the one or more signals were transmitted from a corresponding one of the base station antennas;

calculating a signal to noise ratio for each of the processed signals; and

determining a base station antenna corresponding to the processed signal with the highest calculated signal to noise ratio was used for transmitting the one or more signals.

15. The method of claim 13, wherein said step of processing subsequently received signals from the base station comprises the step of performing channel estimation based on a pilot signal broadcast by the determined base station antenna.

16. The method of claim 13, wherein said step of determining which of the base station antennas was used for transmitting the one or more signals comprises the steps of:

generating a set of processed signals, each processed signal generated by processing the one or more signals as if transmitted from a corresponding one of the base station antennas;

calculating an error detection value for each processed signal; and

determining a base station antenna corresponding to a processed signal for which a calculated error detection value matches an error detection value included with the one or more signals was used for transmitting the one or more signals.

17. A method for use in a mobile station, comprising the steps of:

receiving one or more signals from a base station;

determining a set of antenna weights applied at the base station in transmitting the one or more signals based on a set of processed signals, each processed signal generated by processing the one or more signals according to a different set of antenna weights; and

processing the one or more signals according to the determined set of antenna weights.

18. The method of claim 17, wherein said step of determining comprises:

calculating an error detection value for each processed signal; and

determining a set of antenna weights corresponding to a processed signal for which the calculated error detection value matches an error detection value included with the one or more signals was used for transmitting the one or more signals.

19. The method of claim 17, wherein:

the antenna control information comprises a field having a range of values, each corresponding to a different set of antenna weights; and

each processed signal is generated by processing the one or more signals according to a set of antenna weights corresponding to a value of the antenna control information field.

20. The method of claim 17, wherein said step of determining the antenna weights applied at the base station comprises calculating a signal to noise ratio for each of the processed signals.

21. The method of claim 17, further comprising the steps of:

transmitting to the base station, prior to said step of receiving one or more signals from the base station, antenna control information indicative of a set of generated antenna weights to be applied at the base station; and

comparing the determined set of antenna weights to the generated antenna weights to verify the base station properly received the antenna control information transmitted to the base station.

22. A mobile station comprising:

means for generating antenna weights to be applied at a base station having a plurality of antennas;

means for transmitting antenna control information indicative of the generated antenna weights to the base station;

means for determining, based on one or more signals received from the base station, antenna weights applied at the base station in transmitting the one or more signals; and

means for processing the one or more signals or subsequent signals as if transmitted from the base station using the determined antenna weights.

23. The mobile station of claim 22, further comprising means for comparing the generated antenna weights to the determined antenna weights to verify the base station properly received the antenna control information.

24. The mobile station of claim 22, wherein the one or more signals comprise a feed forward message containing antenna control information indicative of the antenna weights applied at the base station.

25. The mobile station of claim 22, wherein the means for determining is configured to generate a set of processed signals, each generated by processing the one or more signals as if transmitted from the base station using a different set of antenna weights.

26. The mobile station of claim 25, wherein the means for determining is configured to determine the antenna weights applied at the base station based on signal to noise ratios calculated for the set of processed signals.

27. The mobile station of claim 25, wherein the means for determining is configured to determine the antenna weights based on error detection values calculated for the set of processed signals and an error detection value transmitted within the one or more signals.

28. A base station comprising:

a plurality of antennas;

means for receiving, from a mobile station, a feedback message including antenna control information indicative of antenna weights to be used for transmissions from the plurality of antennas; and

means for transmitting, to the mobile station, a feed forward message including the antenna control information, as received in the feedback message, and for subsequently transmitting one or more signals to the mobile station from the plurality of antennas using the antenna weights indicated by the antenna control information.

29. The base station of claim 28, wherein the base station further comprises a weight generator for generating a set of antenna weights based on a set of encoded bits included in the antenna control information.

30. The base station of claim 28, wherein the antenna control information indicates a selected one of the plurality of antennas to be used for transmitting the one or more signals.