Equalizer with extended channel estimation for a receiver in a digital transmission system

• US 6,002,716 A
• Filed: 11/25/1997
• Issued: 12/14/1999
• Est. Priority Date: 04/12/1996
• Status: Expired due to Term

• Current Assignee: ST-Ericcson SA (Telefonaktiebolaget LM Ericsson)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Fischer, Robert, Schramm, Peter, Huber, Johannes, Gerstacker, Wolfgang, Meyer, Raimund
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): TRAN, CONGVAN
• Application Number:
  US08/952,832
• Time in Patent Office: 749 Days
• Field of Search: 375/229, 375/231, 375/232, 375/233, 375/210, 375/340, 375/341, 375/343, 375/316, 370/290, 370/291, 370/292, 364/724.01, 364/724.16, 364/724.19, 364/724.2
• US Class Current: 375/231
• CPC Class Codes: H04L 12/5692 Selection among different networks
• CPC Class Codes: H04L 25/0236 using estimation of the other symbols

Abstract

A digital transmission system comprising a receiver, the receiver including a receiver input stage and a digital memory for storing a sequence of binary symbols of sample values, formed in the receiver input stage, of a signal distorted by a transmission channel, and an equalizer for forming a sequence of binary estimates from the sample values by an impulse response of a substitute system describing the transmission channel, the impulse response being determined by first correlations of coefficients of a known training sequence with the sample values of a part of the known training sequence extended by at least one binary symbol. To make a channel estimation possible for a higher degree of the impulse response of the transmission channel, and also to carry out the channel estimation always with a maximum quality, a variable first correlation window size and a variable number of first correlations are used for adapting the impulse response of the substitute system to the impulse response of the transmission channel. A reduction of the correlation window size enables more cross-correlation values to be formed with one sequence of sample values, so that an increase of the degree of the impulse response of the estimated transmission channel becomes possible. With a more favorable transmission behavior, the correlation window size can be extended by one or more known binary symbols, so that the quality of the estimate of the impulse response is enhanced.

Claims

1. A digital transmission system having a receiver, said receiver comprising:

a receiver input stage and a digital memory for storing a sequence of binary symbols of sample values formed in the receiver input stage of a signal distorted by a transmission channel, and

an equalizer for forming a sequence of binary estimates from the sample values using an impulse response of a substitute system describing the transmission channel, said impulse response being determined by first correlations of coefficients of a known training sequence with the sample values of a part of the known training sequence extended by at least one binary symbol;

wherein a variable first correlation window size and a variable number of first correlations are used for adapting the impulse response of the substitute system to the impulse response of the transmission channel; and

wherein the coefficients of the known training sequence reduced or extended by said at least one binary symbol are used for forming the first correlations with the sample values of the part of the extended training sequence.

2. A digital transmission system having a receiver, said receiver comprising:

a receiver input stage and a digital memory for storing a sequence of binary symbols of sample values formed in the receiver input stage of a signal distorted by a transmission channel, and

an equalizer for forming a sequence of binary estimates from the sample values using an impulse response of a substitute system describing the transmission channel, said impulse response being determined by first correlations of coefficients of a known training sequence with the sample values of a part of the known training sequence extended by at least one binary symbol;

wherein a variable first correlation window size and a variable number of first correlations are used for adapting the impulse response of the substitute system to the impulse response of the transmission channel; and

wherein the first correlations are combined with a vector, said vector comprising a multiplication matrix having elements which are formed by second correlations of coefficients of the known training sequence reduced or extended by said at least one binary symbol with a respective part of the training sequence extended by said at least one binary symbol.

3. A digital transmission system as claimed in claim 2, further comprising a memory for storing the respective matrix for each training sequence and each reduction and extension of the respective training sequence.

4. A digital transmission system having a receiver, said receiver comprising:

a receiver input stage and a digital memory for storing a sequence of binary symbols of sample values formed in the receiver input stage of a signal distorted by a transmission channel, and

an equalizer for forming a sequence of binary estimates from the sample values using an impulse response of a substitute system describing the transmission channel, said impulse response being determined by first correlations of coefficients of a known training sequence with the sample values of a part of the known training sequence extended by at least one binary symbol;

wherein a variable first correlation window size and a variable number of first correlations are used for adapting the impulse response of the substitute system to the impulse response of the transmission channel; and

wherein, for adapting the impulse response of the substitute system to the impulse response of the transmission channel, at least one repetition of the formation of the first correlations is performed, so that the respective beginning of the training sequence in the sample values is determined by means of the preceding correlations, and the most favorable correlation window size are used for the repetition.

5. A receiver comprising:

a receiver input stage and a digital memory for storing a sequence of binary symbols of sample values formed in the receiver input stage of a signal distorted by a transmission channel, and

an equalizer for forming a sequence of binary estimates from the sample values using an impulse response of a substitute system describing the transmission channel, said impulse response being determined by first correlations of coefficients of a known training sequence with the sample values of a part of the known training sequence extended by at least one binary symbol;

wherein a variable first correlation window size and a variable number of first correlations are used for adapting the impulse response of the substitute system to the impulse response of the transmission channel; and

wherein the coefficients of the known training sequence reduced or extended by said at least one binary symbol are used for forming the first correlations with the sample values of the part of the extended training sequence.