Secure Communication over Fading Channels

TL;DR

This paper investigates the secrecy capacity of fading broadcast channels with confidential messages, deriving capacity regions and optimal power allocations, and analyzing ergodic and outage performance for secure communication.

Contribution

It establishes the secrecy capacity region for parallel and Gaussian fading broadcast channels with confidential messages, including optimal power allocation strategies.

Findings

Secrecy capacity region for parallel BCC derived

Optimal power allocation for Gaussian BCC established

Analysis of ergodic and outage performance conducted

Abstract

The fading broadcast channel with confidential messages (BCC) is investigated, where a source node has common information for two receivers (receivers 1 and 2), and has confidential information intended only for receiver 1. The confidential information needs to be kept as secret as possible from receiver 2. The broadcast channel from the source node to receivers 1 and 2 is corrupted by multiplicative fading gain coefficients in addition to additive Gaussian noise terms. The channel state information (CSI) is assumed to be known at both the transmitter and the receivers. The parallel BCC with independent subchannels is first studied, which serves as an information-theoretic model for the fading BCC. The secrecy capacity region of the parallel BCC is established. This result is then specialized to give the secrecy capacity region of the parallel BCC with degraded subchannels. The secrecy capacity region is then established for the parallel Gaussian BCC, and the optimal source power allocations that achieve the boundary of the secrecy capacity region are derived. In particular, the secrecy capacity region is established for the basic Gaussian BCC. The secrecy capacity results are then applied to study the fading BCC. Both the ergodic and outage performances are studied.