Space-time matrix modulation: extension to unknown doubly selective MIMO channels

Most transmission schemes for MIMO channels assume (i) a block fading channel without delay spread and (ii) availability of channel state information at the receiver. Here, we extend the space-time matrix modulation (STMM) scheme and the iterative demodulation algorithm that we introduced previously (Arte´s, H. and Hlawatsch, F., Proc. IEEE ICASSP-2001, p.2153-6, 2001; Proc. IEEE ICASSP-2002, p.2225-8, 2002; Arte´s et al., Proc. 39th Allerton Conf. Commun., Contr, Comput., p.466-75, 2001) to unknown, doubly selective MIMO channels, i.e., delay/Doppler-spread MIMO channels that are unknown to the receiver. We show that the structure inherent in STMM allows perfect reconstruction of the data when transmitting over an unknown doubly selective channel (apparently, this is not currently possible with other transmission schemes). Numerical simulations demonstrate significant performance advantages of STMM over Cayley differential unitary space-time modulation.