Interference cancellation in a spread spectrum communication system

• US 7,545,846 B2
• Filed: 12/13/2005
• Issued: 06/09/2009
• Est. Priority Date: 09/10/1999
• Status: Expired due to Fees

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Reznik, Alexander, Mesecher, David K., Grieco, Donald M., Cheung, Gary
• Primary Examiner(s): Ghebretinsae; Temesghen
• Application Number:
  US11/301,666
• Publication Number:
  US 20060093020A1
• Time in Patent Office: 1,274 Days
• Field of Search: 375/148, 375/346, 375/144, 375/130, 375/146, 375/147, 375/267, 375/347, 375/295, 370/320, 370/335, 370/342
• US Class Current: 375/130
• 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 code division multiple access communication system transmits a pilot and traffic signal over a shared spectrum. The pilot and traffic signal have an associated code and are received over the shared spectrum. The received signals are sampled and the samples are delayed to produce a window. A weighted value for each despread pilot code window sample is determined using an adaptive algorithm. Each window sample is despread with a traffic code. Each despread traffic code window sample is weighted according to a weight corresponding to its respective pilot code sample.

Claims

1. A wireless transmit receive unit (WTRU) comprising:

a data signal generator configured to produce a data signal;

a plurality of mixers configured to produce a plurality of spread data signals, wherein each mixer is configured to mix the data signal with a different pseudo random chip code sequence to produce a different spread data signal;

a plurality of pilot signal generators configured to produce a plurality of spread pilot signals, wherein each pilot signal is spread with a different pseudo random chip code sequence and each pilot signal generator is associated with a different spread data signal;

a plurality of combiners configured to produce a plurality of combined signals, wherein each combined signal is produced as a result of combining one of the pilot signals with one of the spread data signals;

a modulator configured to modulate the combined signals to a carrier frequency; and

an array of antennas configured to radiate the plurality of combined signals over a shared spectrum at the carrier frequency, wherein each antenna is associated with a different modulated combined signal.

2. A base station comprising:

a data signal generator configured to produce a data signal;

a plurality of mixers configured to produce a plurality of spread data signals, wherein each mixer configured to mix the data signal with a different pseudo random chip code sequence to produce a different spread data signal;

a plurality of pilot signal generators configured to produce a plurality of spread pilot signals, wherein each pilot signal is spread with a different pseudo random chip code sequence and each pilot signal generator is associated with a different spread data signals;

a plurality of combiners configured to produce a plurality of combined signals, wherein each combined signal is produced as a result of combining one of the pilot signals with one of the spread data signals;

a modulator configured to modulate the combined signals to a carrier frequency; and

an array of antennas configured to radiate the plurality of combined signals over a shared spectrum at the carrier frequency, wherein each antenna is associated with a different modulated combined signal.

3. A wireless transmit receive unit (WTRU) comprising:

a plurality of data signal generators configured to produce a set of data signals;

a plurality of sets of mixers configured to produce a plurality of spread data signals, wherein each mixer in each set of mixers is configured to mix one of the data signals in each set of data signals with a different pseudo random chip code sequence to produce a plurality of sets of spread data signals;

a plurality of pilot signal generators configured to produce a pilot signal spread with a different pseudo random chip code sequence, wherein each pilot signal generator is associated with a different spread data signal;

a plurality of combiners configured to produce a plurality of combined signals, wherein each combined signal is produced as a result of combining one of the pilot signals with one of the sets of spread data signals;

a modulator configured to modulate the combined signals to a carrier frequency; and

an array of antennas configured to radiate the plurality of combined signals over a shared spectrum at the carrier frequency, wherein each antenna is associated with a different modulated combined signal.

4. A base station comprising:

a plurality of data signal generators configured to produce a set of data signals;

a plurality of sets of mixers configured to produce a plurality of spread data signals, wherein each mixer in each set of mixers is configured to mix one of the data signals in each set of data signals with a different pseudo random chip code sequence to produce a plurality of sets of spread data signals;

a plurality of pilot signal generators configured to produce a pilot signal spread with a different pseudo random chip code sequence, wherein each pilot signal generator is associated with a different spread data signal;

a plurality of combiners configured to produce a plurality of combined signals, wherein each combined signal is produced as a result of combining one of the pilot signals with one of the sets of spread data signals;

a modulator configured to modulate the combined signals to a carrier frequency; and

an array of antennas configured to radiate the plurality of combined signals over a shared spectrum at the carrier frequency, wherein each antenna is associated with a different modulated combined signal.

5. A wireless transmit receive unit (WTRU) comprising:

an antenna configured to receive a plurality of combined signals over a shared spectrum at a carrier frequency;

a demodulator configured to demodulate the received combined signals to a baseband frequency;

an analog to digital converter configured to convert the combined signals to digital samples;

a filtering device configured to process a plurality of pilot signals from the combined signals;

a first plurality of despreaders configured to despread the digital samples with delayed versions of the pilot signals to produce a window of despread pilot code window samples, wherein the window has evenly time spaced samples;

an adaptive algorithm block configured to determine a weight for each despread pilot code window sample using a minimum mean square error algorithm;

an adaptive filter configured to process the received signal with the determined weights to produce a weighted received signal; and

a second despreader configured to despread the weighted received signal to recover the data of the received signals.

6. A base station comprising:

an antenna configured to receive a plurality of combined signals over a shared spectrum at a carrier frequency;

a demodulator configured to demodulate the received combined signals to a baseband frequency;

an analog to digital converter configured to convert the combined signals to digital samples;

a filtering device configured to process a plurality of pilot signals from the combined signals;

a first plurality of despreaders configured to despread the digital samples with delayed versions of the pilot signals to produce a window of despread pilot code window samples, wherein the window has evenly time spaced samples;

an adaptive algorithm block configured to determine a weight for each despread pilot code window sample using a minimum mean square error algorithm;

an adaptive filter configured to process the received signal with the determined weights to produce a weighted received signal; and

a second despreader configured to despread the weighted received signal to recover the data of the received signals.