System and method of estimating equalizer performance in the presence of channel mismatch

A data communication system comprising:

• a decision feedback equalizer.(DFE);
• a receiving system for-use with the DFE for providing a mean square error (MSE) of a performance of the DFE under arbitrary channel mismatch conditions, the receiving system including:
• receiving means for receiving data sent to the communication system, the receiving means including channel means mismatched with the DFE;
• the channel means coupled to the DFE for transmitting to the DFE the data sent to the communication system, the channel means contributing filter and noise components to the data sent to the communication system which causes said arbitrary channel mismatch conditions;
• the DFE including:
• input means coupled to the channel means for receiving the data sent to the communication system transmitted by the channel means and having the filter and noise components contributed by the channel means, the filter components described by .vertline.H.sub.t (e.sup.jw).vertline..sup.2 during a training sequence for the DFE and by .vertline.H(e.sup.jw).vertline..sup.2 during decoding, the noise components described by N.sub.t (e.sup.jw) during the training sequence and N(e.sup.jw) during the decoding;
• and
• means for outputting an approximation of the data sent to the communication system without the filter and noise components;
• the MSE determined according to ##EQU9##

A data retrieval system comprising:

• a storage system having a read/write head for retrieving and receiving data from the storage system;
• a receiving system for providing a mean square error (MSE) of a performance of the storage system, the receiving system including:
• a data channel coupled to the read/write head for carrying the data retrieved from the storage system, the data channel contributing filter and noise components;
• equalizer means coupled to the data channel for receiving the data retrieved from the storage system having the filter and noise components, and for eliminating the filter and noise components from the data retrieved from the storage system, the filter components described by .vertline.H.sub.t (e.sup.jw).vertline..sup.2 during training of the receiving system and by .vertline.H(e.sup.jw).vertline..sup.2 during decoding, the noise components described by N.sub.t (e.sup.jw) during the training of the receiving system and N(e.sup.jw) during the decoding, the MSE determined according to ##EQU10## if the equalizer means is a linear equalizer, and according to ##EQU11## if the equalizer means is a decision feedback equalizer.

A method for operating and evaluating an equalizer, comprising the steps of:

• transmitting an information sequence to the equalizer over an input channel;
• the equalizer receiving an input sequence comprising the information sequence, channel filter spectral data, and channel noise;
• pre-determining and defining the channel filter spectral data according to .vertline.H.sub.t (e.sup.jw).vertline..sup.2 ;
• training the equalizer according to the pre-determined channel filter spectral data defined by .vertline.H.sub.t (e.sup.jw).vertline..sup.2 ;
• pre-determining and defining the channel noise according to N.sub.t (e.sup.jw);
• training the equalizer according to the pre-determined channel noise defined by N.sub.t (e.sup.jw);
• the equalizer outputting an estimate of the information sequence in response to the input sequence received over the input channel according to channel filter spectral data defined by .vertline.H(e.sup.jw).vertline..sup.2 and channel noise defined by N(e.sup.jw);
• determining a mean square error of the equalizer according to ##EQU12## the equalizer is a linear equalizer;
• and determining a mean square error of the equalizer according to ##EQU13## if the equalizer is a decision feedback equalizer.

A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for evaluating a performance of a receiver by providing a mean square error of the receiver's output, said method steps comprising:

• retrieving receiver data which describes a type of the receiver;
• retrieving filter spectral data which describes characteristics of a receiver input channel filter;
• defining the filter spectral data according to .vertline.H.sub.t (e.sup.jw).vertline..sup.2 during training of the receiver and according to .vertline.H(e.sup.jw).vertline..sup.2 during decoding;
• retrieving noise spectral data which describes noise characteristics of the receiver input channel;
• defining the noise spectral data according to N.sub.t (e.sup.jw) during the training of the receiver and according to N(e.sup.jw) during the decoding;
• processing the filter and the noise spectral data to form intermediate variables;
• determining the MSE of the receiver according to ##EQU14## if the receiver data indicates that the receiver is a linear equalizer;
• and
• determining the MSE of the receiver according to ##EQU15## if the receiver data indicates that the receiver is a decision feedback equalizer.

An article of manufacture for use in a computer system having a receiver for receiving transmitted data;

• said article of manufacture comprising a computer usable medium having computer readable program code means embodied in said medium, said program code means for causing a computer to effect:
• retrieving receiver data which describes a type of the receiver;
• retrieving filter spectral data which describes characteristics of a receiver input channel filter;
• defining the filter spectral data according to .vertline.H.sub.t (e.sup.jw).vertline..sup.2 during training of the receiver and according to .vertline.H(e.sup.jw).vertline..sup.2 during decoding;
• retrieving noise spectral data which describes noise characteristics of the receiver input channel;
• defining the noise spectral data according to N.sub.t (e.sup.jw) during the training of the receiver and according to N(e.sup.jw) during the decoding;
• processing the filter and the noise spectral data to form intermediate variables;
• determining the MSE of the receiver according to ##EQU16## if the receiver data indicates that the receiver is a linear equalizer;
• and
• determining the MSE of the receiver according to ##EQU17## receiver is a decision feedback equalizer.