Abstract
Abstract In this paper, a joint subcarrier and power allocation algorithm is proposed to improve the physical layer security in cooperative orthogonal frequency division multiple access (OFDMA) networks, where several source-destination pairs and one untrusted relay are involved. The relay is friendly and intends to help these pairs to enhance their communications. However, it may be overheard by a malicious eavesdropper at the same time. To optimize the joint subcarrier and power allocation with low complexity, we divide the optimization problem into two simpler subproblems. Firstly, the subcarriers are assigned to the source-destination pairs by employing the dual approach under the assumption that the relay power is equally allocated to all the subcarriers. Then, the relay power is allocated to the subcarriers based on the alternative ascending clock auction mechanism. In addition, we prove that the two subproblems can converge after a finite number of iterations. We also find that the proposed auction is cheat-proof and, thus, can avoid the cheating behaviors in the auction process. Numerical results demonstrate that our proposed algorithm can effectively improve the system sum secrecy rate, and the convergence performance is also desirable.
Highlights
Cooperative relaying with orthogonal frequency division multiple access (OFDMA) has recently emerged as a promising technology to achieve the virtual spatial diversity in the wireless networks, which has been adopted in the fourth-generation mobile communication standard
The relay power is allocated to the subcarriers according to the ACA-A mechanism
We assign the subcarriers to the source-destination pairs by utilizing the dual approach under the assumption that the power is allocated to all the subcarriers
Summary
Cooperative relaying with orthogonal frequency division multiple access (OFDMA) has recently emerged as a promising technology to achieve the virtual spatial diversity in the wireless networks, which has been adopted in the fourth-generation mobile communication standard. Physical layer security is improved by utilizing jamming power allocation for the two-way untrusted relaying based on the Stackelberg game in [5]. A cooperative OFDMA network is considered, where there exist several source-destination pairs and one untrusted relay. We can try to improve the physical layer security of the network by jointly optimizing the subcarrier and relay power allocation policies. A novel joint subcarrier and power allocation algorithm is proposed to improve the physical layer security for the cooperative OFDMA networks. This algorithm reduces the complexity of optimal joint resource allocation and can ensure all the users’ secrecy rate effectively. In the following two sections, the dual-based subcarrier assignment and the ACA-A-based power allocation are respectively introduced
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