Discrete Memoryless Interference and Broadcast Channels With Confidential Messages: Secrecy Rate Regions

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We study <emphasis emphasistype="boldital">information-theoretic security</emphasis> for discrete memoryless <emphasis emphasistype="boldital">interference</emphasis> and <emphasis emphasistype="boldital">broadcast</emphasis> channels with independent confidential messages sent to two receivers. Confidential messages are transmitted to their respective receivers while ensuring mutual information-theoretic secrecy. That is, each receiver is kept in total ignorance with respect to the message intended for the other receiver. The secrecy level is measured by the equivocation rate at the eavesdropping receiver. In this paper, we present inner and outer bounds on secrecy capacity regions for these two communication systems. The derived outer bounds have an identical mutual information expression that applies to both channel models. The difference is in the input distributions over which the expression is optimized. The inner bound rate regions are achieved by <emphasis emphasistype="boldital">random binning</emphasis> techniques. For the broadcast channel, a <emphasis emphasistype="boldital">double-binning</emphasis> coding scheme allows for both joint encoding and preserving of confidentiality. Furthermore, we show that, for a special case of the interference channel, referred to as the <emphasis emphasistype="boldital">switch</emphasis> channel, derived bounds meet. Finally, we describe several transmission schemes for Gaussian interference channels and derive their achievable rate regions while ensuring mutual information-theoretic secrecy. An encoding scheme in which transmitters dedicate some of their power to create <emphasis emphasistype="boldital">artificial noise</emphasis> is proposed and shown to outperform both time-sharing and simple multiplexed transmission of the confidential messages. </para>