This paper deals with the comparison of two multi carrier modulation techniques over existing copper twisted pairs: the Discrete Multi Tone (DMT) modulation and the Multi Carrier Code Division Multiple Access (MC-CDMA) modulation. The first form has been proposed for Asymmetrical Digital Subscriber Line (ADSL) [3]. However in ADSL, the wire pairs suffer from disturbances such as transients, radio-frequency noise. Among them, impulse noise is considered to be one of the most damaging impairments. Then, our proposal intends to limit the effects of such a noise thanks to the use of the latter form of modulation which combines multi carrier technique with spread spectrum. In order to improve the performances of the system proposed still further, various detection techniques are studied. In this context, we show that the MC-CDMA technique presents better performances than the normalised ADSL technique under identical simulation parameters (data rate, bandwith, transmitted power, coding, interleaver).