Multiuser loading algorithms for multicarrier systems with embedded constellations

This paper formulates the problem of embedded modulation applied to a multiuser multicarrier system. These embedded multiuser optimization problems are shown to be convex, for which globally optimal solutions can be computed efficiently. We also show that these embedded problems are convex relaxations of the combinatorial FDMA multiuser problems and thus provide performance bounds to the optimal and asymptotically optimal solutions proposed by Hoo, Tellado and Cioffi (see IEEE Global Telecommunications Conf. (Globecom), p.25-30, 1998 and IEEE PIMRC, p.278-82, 1998)