Algebraic coding/decoding multi-user scheme

A new scheme of multiple access using T-user codes over QAM modulation is presented. The new T-user codes are based on rotated constellations such that the resulting sum of all rotated versions of the considered QAM constellation, is uniquely decodable (Kasami and Lin, 1976). Furthermore, the minimum squared Euclidean distance d/sub m//sup 2/(S) of the resulted constellation is maximized over the group of rotations. Over the noiseless channel, we give a detection algorithm that profits from the algebraic structure of the T-user code.