Channel equalization using adaptive subband filters

A novel channel equalization scheme based on adaptive subband filtering is described and analyzed. The structure integrates simultaneous transmission of training and data sequences over separate subbands. The use of crossband filters in a subband equalizer is shown to enable exact reconstruction of an equivalent fullband equalizer, thereby avoiding delay and aliasing. Structural relationships between the subbands are derived that demonstrate the need to use only a single subband error signal to adjust the entire fullband equalizer. Adaptation based only on the training subband thus permits equalization of the data subbands. Performance benefits and the relationship to OFDM schemes are noted.