Confidential Broadcasting and Service Integration in Millimeter Wave Systems

This paper focuses on the transmit design for efficient implementation of confidential broadcasting and service integration 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 to tradeoff the secrecy rates at the two receivers. We obtain the secrecy rate regions by varying a power allocation ratio. On the other hand, in service integration, a multicast message intended for both receivers is introduced in the system. With MF and PMF schemes used for confidential message transmission, we further consider the beamforming design of the multicast message, such that the achievable multicast rate is maximized. The associated optimization problem admits a closed-form solution, and then the secrecy rate region can be obtained still by varying a power allocation ratio. We also compare our proposal with the globally optimal schemes in terms of achievable performance and implementation complexity. Finally, numerical results are presented to verify the efficacy of our proposed method.