Performance-Improved Secure OFDM Transmission Using Chaotic Active Constellation Extension

We propose and demonstrate a physical-layer security scheme using chaotic active constellation extension (ACE) in orthogonal frequency division multiplexing (OFDM). A super OFDM frame is generated by chaotic frame interleaving in ACE, where hyper digital chaos is applied to generate the chaotic interleaving vectors. A huge key space of size 2048! is provided via the multi-fold encryption to guarantee the secure OFDM data transmission, while the transmission performance is effectively improved via the chaotic ACE algorithm. Secure transmission of 8.9-Gb/s 16-QAM encrypted OFDM signals is demonstrated over a 20-km standard single-mode fiber, which shows reliable robustness against any exhaustive attacks. Moreover, the proposed chaotic ACE scheme improves the spectral efficiency of OFDM transmission, since it does not require any sideband to transmit the frame-interleaving information.