Time domain equalization for ADSL technology and its optimization

The methods for compensating unfavorable properties of the transmission path in ADSL are compared. On the basis of measuring the transmission properties of the telephone channel during ADSL initialization, the optimum coefficients of the FIR (finite impulse response) digital filter are calculated. The filter realizes the TEQ (time domain equalization) method and processes effectively the impulse response of transmission channel to the length of permitted cyclic prefix. All analyzed methods give roughly the same results and mainly differ in how the limiting assumptions are defined. The TEQ method is described and recommendations are given that should lead to achieving optimum transmission rate for a given interference in the ADSL transmission.