Conditions for a Monotonic Channel Capacity
Journal article, 2015

Motivated by results in optical communications, where the performance can degrade dramatically if the transmit power is sufficiently increased, the channel capacity is characterized for various kinds of memoryless vector channels. It is proved that for all static point-to-point channels, the channel capacity under an equal-power constraint is a nondecreasing function of power. As a consequence, maximizing the mutual information over all input distributions with a certain power is for such channels equivalent to maximizing it over the larger set of input distributions with upperbounded power. The channel coding theorem is formally proved for an equal-power constraint. For interference channels such as optical wavelength-division multiplexing systems, the primary channel capacity is always nondecreasing with power if all interferers transmit with identical distributions as the primary user. Also, if all input distributions in an interference channel are optimized jointly, then the achievable sum-rate capacity is again nondecreasing. The results generalize to the channel capacity as a function of a wide class of costs, not only power.

nonlinear distortion

capacity-cost function

channel capacity

Shannon limit

optical communications

mutual information

Achievable rate

Author

Erik Agrell

Chalmers, Signals and Systems, Communication and Antenna Systems, Communication Systems

IEEE Transactions on Communications

0090-6778 (ISSN)

Vol. 63 3 738-748 6985572

Subject Categories

Communication Systems

DOI

10.1109/tcomm.2014.2381247

More information

Latest update

3/29/2018