Low complexity channel shortening for discrete multitone modulation systems

Abstract

In discrete multitone (DMT) modulation systems, the channel duration can be longer than the cyclic prefix, yielding both inter-block and inter-carrier interference. In order to avoid these effects, time-domain equalization (TEQ) techniques are usually employed before DMT demodulation. This letter introduces a modification of the iterative minimum delay spread (MDS) method proposed by Lopez-Valcarce in [1] to adapt the TEQ coefficients to the channel. The proposed solution is based on a) the approximation to the solution of a set of equation, and b) a new reference time selection. The resulting scheme requires only a single matrix inversion at the last iteration rather than one per iteration, achieving a significantly lower implementation complexity than iterative MDS, while performing similarly in terms of spectral efficiency.