Joint Secured and Robust Technique for OFDM Systems
  This work presents a novel technique for joint secured and robust transmission of orthogonal frequency division multiplexing (OFDM) based communication systems. The proposed system is implemented by developing a new OFDM symbol structure based on symmetric key cryptography. At the receiver side, data detection becomes infeasible without the knowledge of the secret key. For an intruder who tries to detect the data without the knowledge of the key, the signal will be a noise-like signal. In addition to the system security, theoretical and simulation results demonstrated that the proposed system provides time and frequency diversity, which makes the system highly robust against severe frequency-selective fading as well as other impairments such as impulsive noise and multiple access interference. For particular frequency-selective fading channels, the bit error rate (BER) improvements was about 15 dB at BER of 10E-4. 
Al-Dweik, M. Mirahmadi, A. Shami, Z. Ding and R. Hamila
cs.IT math.IT