Publications in Scientific Journals:

G. Tauböck:
"Complex-valued random vectors and channels: Entropy, divergence, and capacity";
IEEE Transactions on Information Theory, 58 (2012), 5; 2729 - 2744.

English abstract:
Recent research has demonstrated significant achievable performance gains by exploiting circularity/noncircularity or properness/improperness of complex-valued signals. In this paper, we investigate the influence of these properties on important information theoretic quantities such as entropy, divergence, and capacity. We prove two maximum entropy theorems that strengthen previously known results. The proof of the first maximum entropy theorem is based on the so-called circular analog of a given complex-valued random vector. The introduction of the circular analog is additionally supported by a
characterization theorem that employs a minimum Kullback-Leibler divergence criterion. In the proof of the second maximum entropy theorem, results about the second-order structure of complex-valued random vectors are exploited. Furthermore, we address the capacity of
multiple-input multiple-output (MIMO) channels. Regardless of the specific distribution of the channel parameters (noise vector and channel matrix, if modeled as random), we show that the capacity-achieving input vector is circular for a broad range of MIMO channels (including coherent and noncoherent scenarios). Finally, we investi- gate the situation of an improper and Gaussian distributed noise vector. We compute both capacity and capacity-achieving input vector and show that improperness increases capacity, provided that the complementary covariance matrix is exploited. Otherwise, a capacity loss occurs, for which we derive an explicit expression.

capacity, circular, circular analog, differential entropy, improper, Kullback-Leibler divergence, multiple-input multiple-output (MIMO), mutual information, noncircular, proper

"Official" electronic version of the publication (accessed through its Digital Object Identifier - DOI)

Electronic version of the publication:

Created from the Publication Database of the Vienna University of Technology.