On the Secrecy Rate Region of a Fading Multiple-Antenna Gaussian Broadcast Channel with Confidential Messages and Partial CSIT

TL;DR

This paper investigates the secrecy rate region of a fading multiple-antenna Gaussian broadcast channel with confidential messages, deriving achievable rates under partial channel state information and analyzing low SNR behavior.

Contribution

It introduces a classification of non-trivial cases and derives the achievable rate region for secure transmission with partial CSIT, including low SNR analysis.

Findings

Both users can achieve positive secrecy rates simultaneously.

The achievable rate region is characterized through covariance matrix optimization.

Numerical results validate the theoretical analysis under secrecy constraints.

Abstract

In this paper we consider the secure transmission over the fast fading multiple antenna Gaussian broadcast channels with confidential messages (FMGBC-CM), where a multiple-antenna transmitter sends independent confidential messages to two users with information theoretic secrecy and only the statistics of the receivers' channel state information are known at the transmitter. We first use the same marginal property of the FMGBC-CM to classify the non-trivial cases, i.e., those not degraded to the common wiretap channels. We then derive the achievable rate region for the FMGBC-CM by solving the channel input covariance matrices and the inflation factor. Due to the complicated rate region formulae, we resort to low SNR analysis to investigate the characteristics of the channel. Finally, the numerical examples show that under the information-theoretic secrecy requirement both users can achieve positive rates simultaneously.