Generalized channel impulse response shortening for discrete multitone transceivers

In discrete multitone (DMT) transceivers, a cyclic prefix, whose length is longer than that of the channel impulse response, is inserted between modulated symbols to avoid the intersymbol interference (ISI). To reduce the inefficiency due to the use of a long cyclic prefix, a finite impulse response filter, known as a time domain equalizer (TEQ), is used to shorten the effective channel impulse response. In addition, the TEQ can be used to suppress the stop-band noise and passband interference such as radio frequency interference (RFI) in DMT systems by changing the TEQ´s spectral shape. We generalize two time-domain TEQ training methods by defining composite squared cost functions and derive the new algorithms for the TEQ which can jointly shorten the channel impulse response and suppress the stop-band noise and passband interference.