Structured unitary space-time autocoding constellations

We recently showed that arbitrarily reliable communication is possible within a single coherence interval in Rayleigh flat fading as the symbol-duration of the coherence interval and the number of transmit antennas grow simultaneously. This effect, where the space-time signals act as their own channel codes, is called autocoding. For relatively short (e.g., 16-symbol) coherence intervals, a codebook of isotropically random unitary space-time signals theoretically supports transmission rates that are a significant fraction of autocapacity with an extremely low probability of error. However a constellation of the required size (typically L = 280) is impossible to generate and store, and due to lack of structure there is little hope of finding a fast decoding scheme. In this paper we propose a random, but highly structured, constellation that is completely specified by log2 L independent isotropically distributed unitary matrices. The distinguishing property of this construction is that ...

• Type: Journal
• Year: 2002
• Where: TIT
• Authors: Thomas L. Marzetta, Babak Hassibi, Bertrand M. Hochwald
• Keywords: Coherence Intervals, Constellation, Random Unitary Space-time, TIT 2002