Optimal Intra-Symbol Spectral Compensation for Multicarrier Modulation

Spectral compensation aims at maximising the throughput of a multicarrier transmission system under a given power spectral density (PSD) constraint. A set of carefully chosen tones, the so called compensation tones, is modulated with a linear combination of the data transmitted over the complementary set of tones. The compensation tones support shaping of the transmit PSD so that the overall transmit power and thus the throughput increase. The contribution of this paper is twofold. First, we compute the optimal solution for a given set of compensation tones - optimal in the sense of maximising the mutual information between transmit and receive blocks for a time-dispersive Gaussian channel known to the transmitter. Second, we present a low-complexity heuristic to find the set of compensation tones