TY - GEN

T1 - Physical modeling of communication systems in information theory

AU - Ivrlač, Michel T.

AU - Nossek, Josef A.

PY - 2009

Y1 - 2009

N2 - It is common in information theoretic channel models to rely on the average squared Euclidean norm of the channel input as being proportional to transmit power. Likewise, it is common to assume noise that is additive, Gaussian, and white. It is a legitimate question to ask, whether such a modeling approach has enough degrees of freedom to capture the physical constraints that are imposed on implementations of a communication system. In this paper, we show that in many, though not all, situations it is indeed possible to obtain a complete physical model, while nevertheless sticking with average squared Euclidean norm as power, and white Gaussian noise. Our systematic approach works in two steps. First, all channel inputs and outputs are replaced by ports, which are defined by two conjugated variables (like voltage and current). By this multi-port modeling approach, we can obtain a complete physical model. Secondly, we introduce linear transformations between the inputs and outputs of the information theoretic channel model on the one hand, and the physical inputs and physical outputs of the communication system, on the other. This approach gives us enough degrees of freedom to obtain a complete information theoretic model, which correctly refiects the physical constraints that are imposed upon the communication system by its environment. We apply the proposed approach to a multi-antenna communication system, and show that it is indeed possible that the channel capacity of multi-antenna systems can grow super-linearly with the number of antennas for large signal to noise ratios.

AB - It is common in information theoretic channel models to rely on the average squared Euclidean norm of the channel input as being proportional to transmit power. Likewise, it is common to assume noise that is additive, Gaussian, and white. It is a legitimate question to ask, whether such a modeling approach has enough degrees of freedom to capture the physical constraints that are imposed on implementations of a communication system. In this paper, we show that in many, though not all, situations it is indeed possible to obtain a complete physical model, while nevertheless sticking with average squared Euclidean norm as power, and white Gaussian noise. Our systematic approach works in two steps. First, all channel inputs and outputs are replaced by ports, which are defined by two conjugated variables (like voltage and current). By this multi-port modeling approach, we can obtain a complete physical model. Secondly, we introduce linear transformations between the inputs and outputs of the information theoretic channel model on the one hand, and the physical inputs and physical outputs of the communication system, on the other. This approach gives us enough degrees of freedom to obtain a complete information theoretic model, which correctly refiects the physical constraints that are imposed upon the communication system by its environment. We apply the proposed approach to a multi-antenna communication system, and show that it is indeed possible that the channel capacity of multi-antenna systems can grow super-linearly with the number of antennas for large signal to noise ratios.

UR - http://www.scopus.com/inward/record.url?scp=70449484498&partnerID=8YFLogxK

U2 - 10.1109/ISIT.2009.5205810

DO - 10.1109/ISIT.2009.5205810

M3 - Conference contribution

AN - SCOPUS:70449484498

SN - 9781424443130

T3 - IEEE International Symposium on Information Theory - Proceedings

SP - 2179

EP - 2183

BT - 2009 IEEE International Symposium on Information Theory, ISIT 2009

T2 - 2009 IEEE International Symposium on Information Theory, ISIT 2009

Y2 - 28 June 2009 through 3 July 2009

ER -