Secrecy Capacity Region of a Multi-Antenna Gaussian Broadcast Channel with Confidential Messages

摘要

In wireless data networks, communication is particularly susceptible toeavesdropping due to its broadcast nature. Security and privacy systems havebecome critical for wireless providers and enterprise networks. This paperconsiders the problem of secret communication over the Gaussian broadcastchannel, where a multi-antenna transmitter sends independent confidentialmessages to two users with information-theoretic secrecy. That is, each userwould like to obtain its own confidential message in a reliable and safemanner. This communication model is referred to as the multi-antenna Gaussianbroadcast channel with confidential messages (MGBC-CM). Under thiscommunication scenario, a secret dirty-paper coding scheme and thecorresponding achievable secrecy rate region are first developed based onGaussian codebooks. Next, a computable Sato-type outer bound on the secrecycapacity region is provided for the MGBC-CM. Furthermore, the Sato-type outerbound prove to be consistent with the boundary of the secret dirty-paper codingachievable rate region, and hence, the secrecy capacity region of the MGBC-CMis established. Finally, two numerical examples demonstrate that both users canachieve positive rates simultaneously under the information-theoretic secrecyrequirement.