Precoder for DMT with insufficient cyclic prefix

Multi-carrier modulation is a modulation technique that enables higher transmission rate than traditional techniques, such as single-carrier quadrature amplitude modulation (QAM) systems. One implementation of multi-carrier modulation technique is discrete multi-tone (DMT). DMT used in asymmetric digital subscriber lines (ADSL) and very high speed DSL (VDSL) systems has a fixed cyclic prefix length. When the impulse response of the channel is longer than the designed prefix length, for instance when the length of the line impulse response is very long, distortion will appear at the channel output in the form of interference between the carriers. This paper describes a method to remove this distortion by introducing a precoder at the transmitter. Although there will be a power increase when the precoder is used, the distortion is significantly reduced, yielding a performance improvement