New Results on Multiple-Input Multiple-Output Broadcast Channels with Confidential Messages

摘要

This paper presents two new results on multiple-input multiple-output (MIMO)Gaussian broadcast channels with confidential messages. First, the problem ofthe MIMO Gaussian wiretap channel is revisited. A matrix characterization ofthe capacity-equivocation region is provided, which extends the previous resulton the secrecy capacity of the MIMO Gaussian wiretap channel to the general,possibly imperfect secrecy setting. Next, the problem of MIMO Gaussianbroadcast channels with two receivers and three independent messages: a commonmessage intended for both receivers, and two confidential messages eachintended for one of the receivers but needing to be kept asymptoticallyperfectly secret from the other, is considered. A precise characterization ofthe capacity region is provided, generalizing the previous results whichconsidered only two out of three possible messages.