A communication apparatus is disclosed including: an analog-front-end circuit for receiving and processing an analog input signal; an analog-to-digital converter (ADC) coupled with the analog-front-end circuit for converting processed signal from the analog-front-end circuit into a digital input signal; and a control unit coupled with the ADC for adjusting at least one resistance and/or at least one capacitance in an analog echo cancellation circuit according to the digital input signal before the analog-front-end circuit receives a training sequence that is the first training sequence transmitted from a second communication apparatus after the second communication apparatus begins communicating with the communication apparatus.