Power-efficient joint resource allocation for multiuser wiretap OFDM channels

In this paper, the resource allocation for multiuser wiretap Orthogonal Frequency-Division Multiplexing(OFDM) systems is investigated to improve the system power efficiency. In such a multiuser wiretap OFDM system, one legitimate transmitter (Alice), multiple legitimate receivers (Bobs), and one eavesdropper (Eve) are simultaneously considered. The time-domain artificial noise (AN) is firstly involved to guarantee the target secrecy rates of multiple Bobs. Different from the traditional sum secrecy rate maximization problem which may result in the unfair transition for Bobs with bad channel gains and more transmit power consumptions, a non-convex transmit power minimization problem is formulated to jointly optimize the power, subcarrier allocation and AN design, in which a target secrecy rate for each individual Bob is ensured. An iterative algorithm is further proposed to solve this power minimization problem by updating the subcarrier, power allocation and AN design alternatively. Numerical simulation results demonstrate the effectiveness of the proposal, including the improvements of system power efficiency and the fairness of multiple Bobs.