Optimization of channel equalizer

• US 6,954,495 B2
• Filed: 12/03/2001
• Issued: 10/11/2005
• Est. Priority Date: 04/06/2000
• Status: Expired due to Fees

• Current Assignee: Nokia Corporation
• Original Assignee: Nokia Corporation
• Inventors: Piirainen, Olli
• Primary Examiner(s): PHU, PHUONG M
• Application Number:
  US09/998,183
• Publication Number:
  US 20020057735A1
• Time in Patent Office: 1,408 Days
• Field of Search: 375229-235, 375/350, 375/346, 708/322, 708/323
• US Class Current: 375/233
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04L 25/03006 Arrangements for removing intersymbol interference

Abstract

A method for carrying out channel equalization in a radio receiver wherein an impulse response is estimated, noise power is determined by estimating a co-variance matrix of the noise contained in a received signal before prefiltering, and tap coefficients of prefilters and an equalizer are calculated. The method comprises determining the noise power after prefiltering by estimating a noise covariance matrix, after which input signals of the channel equalizer are weighted by weighting coefficients obtained from the noise covariance estimation.

Claims

1. A method for carrying out channel equalization in a radio receiver comprising at least one prefilter and a channel equalizer, the method comprising:

estimating a channel impulse response of a received signal in the channel equalization,

determining noise power by estimating a covariance matrix of the noise contained in a received signal before prefiltering the received signal by using the estimated impulse response,

calculating tap coefficients of the prefilters and the channel equalizer equalizer by using the noise power and the impulse response estimate,

determining the noise power after the prefiltering the received signal by estimating a noise variance after the prefiltering, and

weighting input signals of the channel equalizer by weighting coefficients obtained by the estimated noise variance.

2. A method as claimed in claim 1, wherein the signals to be weighted are the impulse response corrected by means of a noise covariance matrix estimate and the received prefiltered signals.

3. A method as claimed in claim 1, wherein the signals supplied to the channel equalizer are weighted by the weighting coefficients that are determined taking biasing in the noise power estimate into account.

4. A method as claimed in claim 1, wherein channel equalization is carried out using a channel equalizer based on the Viterbi algorithm.

5. A method as claimed in claim 1, wherein channel equalization is carried out using a decision feedback channel equalizer.

6. A radio receiver comprising:

means for estimating a channel impulse response of a received signal in the channel equalization,

means for determining noise power of a received signal by estimating a covariance matrix of the noise contained in the received signal before prefiltering the recieved signal by using the estimated impulse response,

means for calculating tap coefficients of prefilters and a channel equalizer by using the noise power and the impulse response estimate,

means for determining the noise power after the prefiltering the received signal by estimating a noise variance after the prefiltering, and

means for weighting input signals of the channel equalizer by weighting coefficients obtained from the noise variance estimation.

7. A radio receiver as claimed in claim 6, wherein the signals to be weighted are the impulse response estimates corrected by means of the noise covariance matrix estimate and the received signals after the prefiltering.

8. A radio receiver as claimed in claim 6, the receiver further comprising means for weighting the signals supplied to the channel equalizer by weighting coefficients that are determined taking biasing in the noise power estimate into account.

9. A radio receiver as claimed in claim 6, the receiver further comprising means a channel equalizer based on the Viterbi algorithm.

10. A radio receiver as claimed in claim 6, the receiver further comprising a decision feedback channel equalizer.

11. A module comprising:

means for estimating a channel impulse response of a received signal in the channel equalization,

means for determining noise power of a received signal by estimating a covariance matrix of the noise contained in the received signal before prefiltering the received signal by using the estimated impulse response,

means for calculating tap coefficients of prefilters and a channel equalizer by using the noise power and the impulse response estimate,

means for determining the noise power after the prefiltering the received signal by estimating a noise variance after the prefiltering, and

means for weighting input signals of the channel equalizer by weighting coefficients obtained from the noise variance estimation.

12. A computer program product comprising:

means for estimating a channel impulse response of a received signal in the channel equalization,

means for determining noise power of a received signal by estimating a covariance matrix of the noise contained in the received signal before prefiltering the received signal by using the estimated impulse response,

means for calculating tap coefficients of prefilters and a channel equalizer by using the noise power and the impulse response estimate,

means for determining the noise power after the prefiltering the received signal by estimating a noise variance after the prefiltering, and

means for weighting input signals of the channel equalizer by weighting coefficients obtained from the noise variance estimation.