Extensions to the theory of differential space-time modulation

A general approach to differential modulation for multiple transmit and receive antennas was proposed by Hughes see IEEE Trans. on Inform. Theory, 1999, and Proc. IEEE Wireless Networking and Communications Conf. (WCNC ´99), vol.1, p.145-149, 1999), and by Hochwald and Sweldens (see IEEE Trans..on Communm., 1999). In this approach, data are differentially encoded using a restricted class of space-time group codes in which each code matrix is square and has equal-energy, orthogonal rows. In this article, we remove the restrictions imposed in the earlier work and extend the theory of differential transmission to arbitrary Slepian-type group codes. This extension leads to new modulation techniques that significantly outperform previously known methods, both for single and multiple antenna systems. Applications to universal channel coding for discrete memoryless channels are also discussed