Abstract
The secure communication that multiple OFDMA-based cell-edge mobile stations (MS) can only transmit confidential messages to base station (BS) through an untrusted intermediate relay (UR) is discussed. Specifically, with the destination-based jamming (DBJ) scheme and fixed MS transmission power assumption, our focus is on the joint BS and US power allocation to maximize system sum secrecy rate. We first analyze the challenges in solving this problem. The result indicates that our nonconvex joint power allocation is equivalent to a joint MS access control and power allocation. Then, by problem relaxation and the alternating optimization approach, two suboptimal joint MS access control and power allocation algorithms are proposed. These algorithms alternatively solve the subproblem of joint BS and UR power allocation and the subproblem of MS selection until system sum secrecy rate is nonincreasing. In addition, the convergence and computational complexity of the proposed algorithms are analyzed. Finally, simulations results are presented to demonstrate the performance of our proposed algorithms.
Highlights
Broadcast is a fundamental property of the wireless medium
In this work, based on the destination-based jamming (DBJ) secure communication protocol [18], joint base station (BS) and untrusted intermediate relay (UR) power allocation to maximize system sum secrecy rate is discussed for the untrusted relay cooperation OFDMA network
We develop the joint power optimization problem and our analysis indicates that the joint power allocation is equivalent to joint mobile stations (MS) access control and power allocation
Summary
Broadcast is a fundamental property of the wireless medium. This property makes wireless communication susceptible to eavesdropping. For the strategies of International Journal of Antennas and Propagation the second type, the cooperating parties improve the secrecy performance of the system by weakening the eavesdropping link (from legitimate transmitter to the eavesdropper), such as the noise-forwarding [13], cooperative jamming [10,11,12, 14], and artificial noise [15] For these works of cooperation enhanced secure communication, an important assumption is that the cooperation node is trustworthy. The following of the paper is organized as follows: system model and cooperation protocol are introduced in Section 2; the joint power allocation problem is discussed in Section 3 and suboptimal algorithms are present therein; selected numerical results are shown in Section 4; and the conclusion is given
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