Cross-layer scheduling for physical layer secrecy and queue stability in a multi-user system

Physical layer security is envisaged to provide secure wireless communications. So far there exist schemes that both achieve physical layer security and maintain a reasonable level of link capacity. However, in all these schemes, capacity of a communication link depends on the channel characteristics of both the communication link and the eavesdropping links. Thus, when packets are scheduled in a wireless network with physical layer security, the most critical task is to select an appropriate link for a new transmission such that the network throughput and quality of services are properly balanced. In this paper, packet scheduling is studied for a wireless network with physical layer security considering beamforming and artificial noise. Particularly, a cross-layer scheduling scheme is developed based on the stochastic optimization theory to maximize the admission rate of all users and guarantee queue stability in each link. The scheme takes into account the constraints of physical layer security in different eavesdropping strategies: colluding and non-colluding. The effectiveness of the scheduling scheme is validated via simulations. The impact of antenna number and eavesdropping strategy to the scheduling scheme is also revealed in the performance results.