On the Capacity of Channels with Unknown Interference.
MICHIGAN UNIV ANN ARBOR COMMUNICATIONS AND SIGNAL PROCESSING LAB
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We model the process of communicating in the presence of interference, which is unknown or hostile, as a two-person zero sum game with the communicator and the jammer as the players. The objective function we consider is the mutual information. The communicators strategies are distributions on the input alphabet and on a set of quantizers. The jammers strategies are distributions on the noise power subject to certain constraints. We consider various conditions on the jammers strategy set and on the communicators knowledge. For the case with the decoder uninformed of the actual quantizer chosen we show that, from the communicators perspective, the worst-case jamming strategy is a distribution concentrated at a finite number of points thereby converting a functional optimization problem into a non-linear programming problem. Moreover, we are able to characterize the worst-case distributions by means of necessary and sufficient conditions which are easy to verify. For the case with the decoder informed of the actual quantizer chosen we are able to demonstrate the existence of saddle-point strategies. The analysis is also seen to be valid for a number of situation where the jammer is adaptive.
- Command, Control and Communications Systems