Receiver method and apparatus with complex pilot filter

• US 6,728,230 B2
• Filed: 01/08/2003
• Issued: 04/27/2004
• Est. Priority Date: 05/28/1996
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tiedemann, Edward G. Jr., Jou, Yu-Cheun, Odenwalder, Joseph P.
• Primary Examiner(s): Patel, Ajit
• Application Number:
  US10/338,971
• Publication Number:
  US 20030128680A1
• Time in Patent Office: 475 Days
• Field of Search: 370/208, 370/209, 370/320, 370/335, 370/342, 370/468, 370/328, 370/329, 370/431, 370/500, 375/130
• US Class Current: 370/335
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04B 7/264 for data rate control
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker
• CPC Class Codes: H04J 13/0048 Walsh
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence

Abstract

Demodulation of a received high rate CDMA wireless signal is obtained by filtering a complex received signal to provide a complex pilot filter signal. The complex pilot filter signal is then use to phase-adjust a set of demodulated subscriber channel signals.

Claims

1. A method for demodulating a received signal comprising:

filtering an in-phase component of a complex despread signal to produce an in-phase pilot filter signal;

filtering a quadrature-phase component of the complex despread signal to produce a quadrature-phase pilot filter signal;

multiplying the in-phase component by a Walsh code to produce an in-phase Walsh despread signal;

multiplying the quadrature-phase component by the Walsh code to produce a quadrature-phase Walsh despread signal;

multiplying the in-phase Walsh despread signal by the in-phase pilot filter signal to produce a first phase-adjusted signal;

multiplying the quadrature-phase Walsh despread signal by the quadrature-phase pilot filter signal to produce a second phase-adjusted signal; and

adding the first phase-adjusted signal to the second phase-adjusted signal to produce a first soft decision data signal.

2. The method of claim 1 further comprising:

complex-multiplying a complex PN-spread signal by a complex PN code to produce the in-phase component and the quadrature-phase component.

3. The method of claim 2 wherein the complex-multiplying comprises:

multiplying an in-phase PN-spread component by an in-phase PN component of a complex PN code to produce a first complex-despread component;

multiplying a quadrature-phase PN-spread component by the in-phase PN component to produce a second complex-despread component;

multiplying the quadrature-phase PN-spread component by a quadrature-phase PN component of the complex PN code to produce a third complex-despread component;

multiplying the in-phase PN-spread component by the quadrature-phase PN component to produce a fourth complex-despread component;

adding the first complex-despread component to the fourth complex-despread component to produce the in-phase component; and

subtracting the third complex-despread component from the second complex-despread component to produce the quadrature-phase component.

4. The method of claim 1 wherein the first soft decision data signal is a power control signal, the method further comprising summing the first soft decision data signal to produce power control soft decision data.

5. The method of claim 1 wherein the first soft decision data signal is an in-phase component of a QPSK data signal, the method further comprising:

multiplying the quadrature-phase Walsh despread signal by the in-phase pilot filter signal to produce a third phase-adjusted signal;

multiplying the in-phase Walsh despread signal by the quadrature-phase pilot filter signal to produce a fourth phase-adjusted signal; and

subtracting the fourth phase-adjusted signal from the third phase-adjusted signal to produce a second soft decision data signal, wherein the second soft decision data signal is a quadrature-phase component of the QPSK data signal.

6. The method of claim 1 wherein the filtering an in-phase component comprises averaging the in-phase component, and wherein the filtering a quadrature-phase component comprises averaging the quadrature-phase component.

7. The method of claim 1 wherein the Walsh code has a duration of fewer than sixty-four chips per orthogonal waveform period.

8. The method of claim 1 further comprising:

four-to-one summing the in-phase component prior to the filtering an in-phase component; and

four-to-one summing the quadrature-phase component prior to the filtering a quadrature-phase component.

9. The method of claim 1 further comprising:

four-to-one summing the in-phase Walsh despread signal; and

four-to-one summing the quadrature-phase Walsh despread signal.

10. An apparatus comprising:

in-phase pilot filter configured to filter an in-phase component of a complex despread signal to produce an in-phase pilot filter signal;

quadrature-phase pilot filter configured to filter a quadrature-phase component of the complex despread signal to produce a quadrature-phase pilot filter signal;

in-phase Walsh multiplier configured to multiply the in-phase component by a Walsh code to produce an in-phase Walsh despread signal;

quadrature-phase Walsh multiplier configured to multiply the quadrature-phase component by the Walsh code to produce a quadrature-phase Walsh despread signal;

first multiplier configured to multiply the in-phase Walsh despread signal by the in-phase pilot filter signal to produce a first phase-adjusted signal;

second multiplier configured to multiply the quadrature-phase Walsh despread signal by the quadrature-phase pilot filter signal to produce a second phase-adjusted signal; and

first summer configured to add the first phase-adjusted signal to the second phase-adjusted signal to produce a first soft decision data signal.

11. The apparatus of claim 10 further comprising a complex PN despreader configured to complex-multiply a complex PN-spread signal by a complex PN code to produce the in-phase component and the quadrature-phase component.

12. The apparatus of claim 11 wherein the complex-PN despreader comprises:

first PN despreader multiplier configured to multiply an in-phase PN-spread component by an in-phase PN component of a complex PN code to produce a first complex-despread component;

second PN despreader multiplier configured to multiply a quadrature-phase PN-spread component by the in-phase PN component to produce a second complex-despread component;

third PN despreader multiplier configured to multiply the quadrature-phase PN-spread component by a quadrature-phase PN component of the complex PN code to produce a third complex-despread component;

fourth PN despreader multiplier configured to multiply the in-phase PN-spread component by the quadrature-phase PN component to produce a fourth complex-despread component;

first PN despreader summer configured to add the first complex-despread despread component to the fourth complex-despread component to produce the in-phase component; and

second PN despreader summer configured to subtract the third complex-despread despread component from the second complex-despread component to produce the quadrature-phase component.

13. The apparatus of claim 10 wherein the first soft decision data signal is a power control signal, the apparatus further comprising a 384-to-one summer configured to sum the first soft decision data signal to produce power control soft decision data.

14. The apparatus of claim 10 wherein the first soft decision data signal is an in-phase component of a QPSK data signal, the apparatus further comprising:

third multiplier configured to multiply the quadrature-phase Walsh despread signal by the in-phase pilot filter signal to produce a third phase-adjusted signal;

fourth multiplier configured to multiply the in-phase Walsh despread signal by the quadrature-phase pilot filter signal to produce a fourth phase-adjusted signal; and

second summer configured to subtract the fourth phase-adjusted signal from the third phase-adjusted signal to produce a second soft decision data signal, wherein the second soft decision data signal is a quadrature-phase component of the QPSK data signal.

15. The apparatus of claim 10 wherein the in-phase pilot filter comprises means for averaging the in-phase component, and wherein the quadrature-phase pilot filter comprises means for averaging the quadrature-phase component.

16. The apparatus of claim 10 wherein the in-phase Walsh multiplier is configured to multiply the in-phase component by a Walsh code having a duration of fewer than sixty-four chips per orthogonal waveform period, and wherein the quadrature-phase Walsh multiplier is configured to multiply the quadrature-phase component by the a Walsh code having a duration of fewer than sixty-four chips per orthogonal waveform period.

17. The apparatus of claim 10 further comprising:

first four-to-one summer configured to sum the in-phase component over four demodulation chips; and

second four-to-one summer configured to sum the quadrature-phase component over four demodulation chips.

18. The apparatus of claim 10 further comprising:

first four-to-one summer configured to sum the in-phase Walsh despread signal over four demodulation chips; and

second four-to-one summer configured to sum the quadrature-phase Walsh despread signal over four demodulation chips.

19. An apparatus comprising:

means for filtering an in-phase component of a complex despread signal to produce an in-phase pilot filter signal;

means for filtering a quadrature-phase component of the complex despread signal to produce a quadrature-phase pilot filter signal;

means for multiplying the in-phase component by a Walsh code to produce an in-phase Walsh despread signal;

means for multiplying the quadrature-phase component by the Walsh code to produce a quadrature-phase Walsh despread signal;

means for multiplying the in-phase Walsh despread signal by the in-phase pilot filter signal to produce a first phase-adjusted signal;

means for multiplying the quadrature-phase Walsh despread signal by the quadrature-phase pilot filter signal to produce a second phase-adjusted signal; and

means for adding the first phase-adjusted signal to the second phase-adjusted signal to produce a first soft decision data signal.