Secure resource allocation for the SISO‐OFDM wiretap channel

Abstract

The broadcast nature of communication systems opens the possibility for attackers to eavesdrop the data and compromise data confidentiality. This study takes the information theoretic security at the physical layer of single-input single-output orthogonal frequency division multiplexing (SISO-OFDM) wiretap system into account, in which, different signal-to-noise ratio (SNR) values on the legitimate and eavesdropper's receivers are assumed. The optimisation problem for secure resource allocation is formulated. Then, the secrecy rate of the system is used as the objective function for resource allocation. Finally, a power allocation strategy is obtained. The upper bound of the secrecy capacity of the single-user system is proposed as a linear function of legitimate receiver's SNR (dB), based on the mentioned strategy. In addition, an iterative power allocation algorithm is proposed for two-user SISO-OFDM wiretap channel. Results showed that the proposed algorithm is fast and converges to the optimal value in the second iteration. The upper bound linear model is valid in a two-user case when there is a relatively large difference between Bob and Eve SNRs.