Physical Layer Security using Time-Reversal Pre-Coding based OFDM-DCSK Communication System with Artificial Noise Injection

In this paper, Time-Reversal (TR) pre-coding with Artificial Noise (AN) injection is proposed to enhance the physical layer security (PLS) performance in orthogonal Frequency Division Multiplexing-Differential Chaos Shift Keying (OFDM-DCSK) system, which is named the TRAN-OFDM-DCSK system. This approach is provided to achieve high data rates, high PL data security, and high reliability performance. The AN signal does not spoil the transmitted data to the genuine receiver, but it reduces the ungenuine detection performance. This system ensures the secrecy of communication to the genuine receiver when the sender knows the Channel State Information (CSI) of the genuine communication link. Still, the information about the instantaneous CSI of a possible eavesdropper does not know the transmitter. The performance of the proposed TRAN-OFDM-DCSK system is investigated and tested under a Flat Rayleigh Fading Channel (FRFC). An approach is provided for calculating the performance of Bit Error Rate (BER), and the expression of BER analytical is derived and compared with the simulation version. Furthermore, the ergodic Secrecy Rate (SR) is derived and analyzed at the genuine and ungenuine receivers over the FRFC. Our result shows the best performance for the genuine receiver compared with ungenuine receiver regarding secrecy performance for BER and SR

A study on secure pilot signal design for OFDM systems

Abstract-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