Interference cancellation in a spread spectrum communication system

• US 6,278,726 B1
• Filed: 09/11/2000
• Issued: 08/21/2001
• Est. Priority Date: 09/10/1999
• Status: Expired due to Term

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Reznik, Alexander, Mesecher, David K., Cheung, Gary, Grieco, Donald
• Primary Examiner(s): GHEBRETINSAE, TEMESGHEN
• Application Number:
  US09/659,858
• Time in Patent Office: 344 Days
• Field of Search: 375/130, 375/144, 375/148, 375/346, 370/320, 370/335, 370/342
• US Class Current: 375/148
• CPC Class Codes: H04B 1/7097 Interference-related aspects
• CPC Class Codes: H04B 1/7103 the interference being multiple access interference
• CPC Class Codes: H04B 1/712 Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04B 7/0613 using simultaneous transmission H04B7/0686 takes precedence
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0678 using different spreading codes between antennas code allocation H04J13/16
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04J 13/0003 Code application, i.e. aspects relating to how codes are applied to form multiplexed channels

Abstract

A transmitter transmits a spread spectrum pilot and data signal. Each signal has an associated chip code. A receiver receives the transmitted pilot and data signal. The received pilot signal is filtered using the pilot chip code and weights are determined for components of the received pilot signal using an adaptive algorithm. The received data signal is weighted by the determined weights and filtered with the data signal chip code to recover data from the received data signal.

Claims

1. A method for reducing interference in a received spread spectrum data signal in a spread spectrum communication system comprising:

transmitting a spread spectrum pilot signal and data signal, each having an associated chip code;

receiving at a receiver the transmitted pilot and data signals;

filtering the received pilot signal using the pilot signal chip code and determining weights of components of the received pilot signal using an adaptive algorithm; and

filtering the received data signal with the data signal chip code and weighting components of the received data signal with the pilot signal determined weights to recover data from the received data signal.

2. The method of claim 1 wherein the adaptive algorithm is a minimum mean square error algorithm.

3. The method of claim 1 wherein the adaptive algorithm is a least mean squared algorithm.

4. The method of claim 1 wherein the adaptive algorithm comprises comparing the received filtered pilot signal with an ideal value to produce an error signal and the determining of each pilot signal weight is based on in part on the error signal.

5. The method of claim 4 wherein the ideal value is 1+j.

6. The method of claim 1 wherein the weighting of the received data signal components occurs prior to the filtering of the received data signal.

7. The method of claim 1 wherein the filtering of the received pilot signal is performed by a vector correlator.

8. The method of claim 1 wherein the filtering of the received pilot signal is performed by a RAKE.

9. A receiver for use in a spread spectrum communication system, a transmitter within the communication system transmits a spread spectrum pilot and data signal for reception by the receiver, the pilot and data signal having associated chip codes, the receiver comprising:

an antenna for receiving the pilot and data signal;

means for filtering the received pilot signal using the pilot signal chip code;

means for determining weights of components of the received pilot signal using an adaptive algorithm; and

means for filtering the received data signal with the data signal chip code and weighting components of the received data signal with the pilot signal determined weights to recover data from the received data signal.

10. The receiver of claim 9 wherein the adaptive algorithm is a minimum mean square error algorithm.

11. The receiver of claim 9 wherein the adaptive algorithm is a least mean square algorithm.

12. The receiver of claim 9 wherein the adaptive algorithm comprises comparing the received filtered pilot signal with an ideal value to produce an error signal and the determined weights is based in part on the error signal.

13. The receiver of claim 9 wherein the pilot signal filtering means comprises a vector correlator.

14. The receiver of claim 9 wherein the pilot signal filtering means comprises a RAKE.

15. A user equipment for use in a spread spectrum communication system, the communication system having a base station transmitting a spread spectrum pilot and data signal for reception by the user equipment, the pilot and data signal having associated chip codes, the user equipment comprising:

an antenna for receiving the pilot and data signal;

a vector correlator for filtering the received pilot signal using the pilot signal chip code;

an adaptive algorithm block for determining weights of components of the received pilot signal using an adaptive algorithm;

an adaptive filter for weighting components of the received data signal with the pilot signal determined weights; and

a despreader for filtering the weighted received data signal using the data signal chip code to recover data from the received data signal.

16. The user equipment of claim 15 wherein the adaptive algorithm is a minimum mean square error algorithm.

17. The user equipment of claim 15 wherein the adaptive algorithm is a least mean square algorithm.

18. The user equipment of claim 15 wherein the adaptive algorithm comprises comparing the received filtered pilot signal with an ideal value to produce an error signal and the determined weights is based on in part on the error signal.