Equaliser for digital communications systems and method of equalisation

A computer program product for a processor of a channel equaliser, the computer program product comprising:

• code that supports reception of a data stream generated from a plurality of transmit antenna elements;
• code that generates via a fast transform a packet spectrum of at least a portion of the data stream, the packet spectrum being a transform domain representation;
• code that supports reception of a training sequence for a channel through which the data stream has been sent and code that assesses a channel impulse response for the channel based on the training sequence;
• code that generates via a fast transform a channel impulse response spectrum in the transform domain for the channel impulse response;
• code that equalizes the packet spectrum with the channel impulse response spectrum to produce an equalised packet spectrum in the transform domain;
• and
• code that converts the equalized packet spectrum into time domain equalized data for recovery of information;
• wherein the codes reside in a computer readable medium.

An integrated chip having a controller programmed to provide a channel equalisation function, the controller comprising:

• a first receiver chain arranged, in use, to receive a data stream generated from a plurality of transmit antenna elements;
• a first fast transform function arranged to generate a packet spectrum of at least a portion of the data stream, the packet spectrum being a transform domain representation;
• a second receiver chain arranged, in use, to receive a training sequence for a channel through which the data stream has been sent;
• a channel impulse response estimator for assessing a channel impulse response for the channel based on the training sequence;
• a second fast transform function arranged to generate a channel impulse response spectrum in the transform domain for the channel impulse response;
• an equalizer arranged to equalise the packet spectrum with the channel impulse response spectrum to produce an equalised packet spectrum in the transform domain;
• and
• an inverse transform function arranged to converte the equalised packet spectrum into time domain equalised data for recovery of information.

An equaliser comprising:

• a first input for receiving a data stream generated from a plurality of transmit antenna elements;
• a processor arranged to select a sub-slot of data from the data stream and to implement a fast transform on the sub-slot to generate a packet spectrum for the sub-slot of data, the packet spectrum being a transform domain representation;
• means for storing a channel impulse response spectrum generated from a fast transform of a channel impulse response of a channel through which the data stream has been sent, the channel impulse response spectrum being in the transform domain;
• a least squares spectral ratio comparator coupled to receive the packet spectrum and the channel impulse response spectrum, the least spectra ratio comparator having an output providing an equalised packet spectrum in the transform domain;
• and
• means for converting the equalised packet spectrum into time domain equalised data for recovery of information.

A radio communication device comprising the equaliser having:

• a first input for receiving a data stream generated from a plurality of transmit antenna elements;
• a processor arranged to select a sub-slot of data from the data stream and to implement a fast transform on the sub-slot to generate a packet spectrum for the sub-slot of data, the packet spectrum being a transform domain representation;
• means for storing a channel impulse response spectrum generated from a fast transform of a channel impulse response of a channel through which the data stream has been sent, the channel impulse response spectrum being in the transform domain;
• a least squares spectral ratio comparator coupled to receive the packet spectrum and the channel impulse response spectrum, the least spectral ratio comparator having an output providing an equalised packet spectrum in the transform domain;
• and
• means for converting the equalised packet spectrum into time domain equalised data for recovery of information.

An equaliser comprising an input, a RAM memory block, a RAM sample block, a spectrum ratio calculator having a first input connected to the RAM sample block and a second input connected to a RAM having an impulse response spectrum;

• wherein the equaliser is operable to:
• receive a data stream of digital signals;
• fill a RAM memory block;
• converting the signals by way of at fast Fourier transform operation to provide a sample RAM block Yk (packet spectrum) and providing the signals to a first input of an equaliser;
• and
• receive, at a second input of the equaliser, an impulse response spectrum held within the RAM, which impulse response spectrum is a fast Fourier transform of the channel impulse response;
• thereby to equalise the signals whereby to provide an equalised packet spectrum which undergoes an inverse fast Fourier transform to provide equalised packet waveforms.