Controlled Inter-carrier Interference for Physical Layer Security in OFDM Systems

Performance of OFDM is known to be very sensitive to frequency synchronization errors. By exploiting this feature, a novel technique is proposed to provide secure communication against eavesdropping. The technique is based on introducing self inter-carrier interference to pre-compensate the carrier offset only for the legitimate user. This pre-compensation process depends on both the channel and the local carrier offset of the legitimate user, hence provides another degree of freedom for secrecy. Under the assumption that eavesdropper experiences an uncorrelated channel, his performance is expected to be degraded. Also our approach converts the simple one-tap frequency domain channel equalization to a very complex receiver operation for the eavesdropper. Moreover, the power aspects of this technique are discussed. By setting a threshold in the pre-compensation stage, we provide an acceptable trade-off between the transmitted power and the error performance.