Multiple-antenna signal constellations for fading channels

In this paper we show that the problem of designing eÆcient multiple-antenna signal constellations for fading channels can be related to the problem of nding packings with large minimum distance in the complex Grassmannian space. We describe a numerical optimization procedure for nding good packings in the complex Grassmannian space and report the best signal constellations found by this procedure. These constellations improve signi cantly upon previously known results. Index Terms { multiple-antennas, Rayleigh at-fading, packings in Grassmannian space This work was carried out while the rst author was a summer intern at Bell Labs.