Mitigating clipping noise in multi-carrier systems

Multi-carrier signals such as are used in ADSL and VDSL have a higher peak-to-average ratio than single-carrier signals, and therefore, for a given transmit power and maximum output level of a digital-to-analog converter (DAC) the probability of the transmit signal being clipped is higher. This paper describes two methods of mitigating the effects of clipping: one that trades off clipping noise against increased quantizing noise by scaling a potentially clipped signal, and one that filters the clipping noise to reduce its spectral density at low frequencies where the SNR is expected to be higher.