Patent ID: 7203230

Claim:
A method for implementing a training phase of adaptive channel equalization in a digital communication arrangement comprising a transmitter, a receiver, and a channel, the method comprising: in the transmitter, coding a bit stream into symbols; in the transmitter, forming a transmission signal containing information of the symbols by using one of a QAM-modulation method and a CAP-modulation method; in the transmitter, sending the transmission signal to the channel; in the receiver, receiving the transmission signal from the channel; in the receiver, processing the received transmission signal with a linear equalizer and with an adaptive decision feedback equalizer; and forming at least one stop band on a spectrum of the transmission signal by using at least one band-stop filter, each band-stop filter being located in one of the transmitter and the receiver, the method further comprising: in the transmitter, using a sparse symbol constellation during at least a part of a training period of the adaptive decision feedback equalizer, a number of symbol states of the sparse symbol constellation being smaller than that of a basic symbol constellation used in a normal data transmission state; in the receiver, performing training of the adaptive decision feedback equalizer at least partially using symbol decisions made with a detector of the sparse symbol constellation; and moving the digital communication arrangement from the training phase to the normal data transmission state by replacing in the transmitter, the sparse symbol constellation with the basic symbol constellation used in the normal data transmission state and by replacing in the receiver, the detector of the sparse symbol constellation with a detector of the basic symbol constellation.