A Secrecy and Security Dilemma in OFDM Communications

Kaikai Huang, Kazuhiko Fukawa, Yuyuan Chang

Zhenzhen Gao, Di Shen, Xuewen Liao

Mei Qin, Weidang Lu, Hong Peng +1 more

Reem Melki, Hassan Noura, Mohammad M. Mansour +1 more

Mohammad Reza Javan

In this paper, the problem of resource allocation for OFDM user to guarantee secure communication is considered. There exists an active eavesdropper which is able to either eavesdrop or jam the ongoing information transmission of OFDM user but not both at the same time. The OFDM user aim is to minimize its transmit power over all subcarriers while maintaining its secrecy rate above a predefined threshold. We assume that attacker chooses between jamming and eavesdropping based on the achievable rate of user in each case to minimize the secrecy rate of legitimate user. In addition, we assume that the OFDM user knows the policy of the attacker, and hence it considers the worst case in which the secrecy rate is the minimum between the secrecy rate when attacker jams and when attacker eavesdrops. We evaluate our proposed scheme by simulations and show its effectiveness.

Kenta Umebayashi, F. Nakabayashi, Yasuo Suzuki

In this paper, we investigate a physical layer security technique in an orthogonal frequency-division multiplexing (OFDM) based wireless communications. In an OFDM system, the legitimate transmitter (Alice) can increase secrecy capacity with proper power allocation and/or bit loading methods for example by maximizing mutual information for own communication, i.e. between Alice and the legitimate receiver (Bob). The reason of increasing secrecy capacity is that the power allocation is suitable for the channel state between Alice and Bob but not suitable for the channel state between Alice and the eavesdropper (Eve). In this paper, we investigate a new approach where dummy data is exploited to achieve further improvement of secrecy capacity. Specifically, real data and dummy data are implemented in transmit OFDM symbols and secure pilot signals are employed to inform the receiver about their respective locations. Two secure pilot signal designs are introduced and in both of them it is designed that Bob can easily detect correct real data locations but not for Eve. One of them uses fake pilot signals that cause Eve to mistakenly select dummy data as real data. Numerical results will show that secrecy capacity performance of the first secure pilot signal based secure communication (not using fake signal) is slightly less than the performance of water filling algorithm. One significant advantage of the first secure pilot signal based secure communication is that the computational cost should be significantly less than the water filling algorithm. In addition, we will show that fake pilot signal based secure communication can provide significant gain in secrecy capacity while the computational cost is still small.