Efficient Implementation of Confidential Broadcasting in Millimeter Wave Systems

This paper focuses on the transmit design for efficient implementation of confidential broadcasting in a two-receiver millimeter wave (mmWave) system. In confidential broadcasting, a transmitter broadcasts two confidential messages to two receivers. Each confidential message is intended for one specified receiver and kept perfectly secret from the other. To fully exploit the propagation characteristics of mmWave channels, two heuristic transmit schemes, i.e., matched filter (MF) and partially MF (PMF) schemes, are proposed in this paper to trade off the secrecy rates at the two receivers. We obtain the secrecy rate regions by varying a power allocation ratio. Then we compare our proposal with the globally optimal schemes in terms of achievable performance and implementation complexity. Finally, numerical results demonstrate that our proposed schemes outperform the traditional orthogonal multiple access-based ones and approach the boundary of secrecy capacity regions in some areas.