Marzetta, Thomas L. and Hassibi, Babak and Hochwald, Bertrand M. (2002) Structured unitary spacetime autocoding constellations. IEEE Transactions on Information Theory, 48 (4). pp. 942950. ISSN 00189448. http://resolver.caltech.edu/CaltechAUTHORS:MARieeetit02

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Abstract
We previously 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 spacetime signals act as their own channel codes, is called autocoding. For relatively short (e.g., 16symbol) coherence intervals, a codebook of independent isotropically random unitary spacetime signals theoretically supports transmission rates that are a significant fraction of autocapacity with an extremely low probability of error. The exploitation of spacetime autocoding requires the creation and decoding of extraordinarily large constellationstypically L = 2^80. We make progress on the first part of the problem through 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 any two signals in the constellation are pairwise statistically independent and isotropically distributed. Thus, the pairwise probability of error, and hence the union bound on the block probability of error, of the structured constellation is identical to that of a fully random constellation of independent signals. We establish the limitations of an earlier construction through a subsidiary result that is interesting in its own right: the square (or for that matter, any integer power greater than one) of an isotropically random unitary matrix is not isotropically random, with the sole exception of the onebyone unitary matrix.
Item Type:  Article 

Additional Information:  © Copyright 2002 IEEE. Reprinted with permission. Manuscript received June 13, 2000; revised June 16, 2001. Communicated by M.L. Honig, Associate Editor for Communications. 
Subject Keywords:  Eigenvalues of random matrices, multiple antennas, Rayleigh flat fading, space–time autocoding, unitary space–time modulation, wireless communication 
Record Number:  CaltechAUTHORS:MARieeetit02 
Persistent URL:  http://resolver.caltech.edu/CaltechAUTHORS:MARieeetit02 
Alternative URL:  http://dx.doi.org/10.1109/18.992790 
Usage Policy:  No commercial reproduction, distribution, display or performance rights in this work are provided. 
ID Code:  9023 
Collection:  CaltechAUTHORS 
Deposited By:  Archive Administrator 
Deposited On:  22 Oct 2007 
Last Modified:  26 Dec 2012 09:44 
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