DWMT transceiver equalization using overlap FDE for downlink ADSL

Discrete wavelet multitone (DWMT) modulation is a wavelet transform based technique implemented using perfect reconstruction filter banks. It has been recently proposed for various wireline channels such as digital subscriber loops (DSLs) as a solution to the problems posed by a discrete multitone (DMT) transceiver including interblock interference (IBI) and lower spectral efficiency due to the employment of a cyclic prefix (CP) in the guard interval (GI) for DMT symbols. The greater side lobe attenuation offered by wavelet filter banks results in improved spectral containment and lower IBI in DWMT transceivers. However, no standard equalization technique exists for a DWMT based transceiver so as to remove the effect of channel on the transmitted signal in DWMT systems. This paper proposes the application of overlap frequency domain equalization (OFDE) in DWMT modulated systems and compares the bit error rate (BER) performance with time domain equalization (TDE) technique. It is shown through simulation results that minimum mean square error (MMSE) based OFDE can be applied as an equalization technique for a downlink asymmetric DSL (ADSL) channel with lower computational complexity and BER performance comparable to that of TDE.