Physical-Layer OFDM Data Encryption using Chaotic QAM Mapping

Dynamic QAM mapping schemes are proposed to encrypt the user data in physical-layer using hyper digital chaos for optical orthogonal frequency-division multiplexing (OFDM) transmission. Unlike the traditional physical-layer security schemes such as signal scrambling or permutation of OFDM symbols, the OFDM data is chaotically re-distributed onto any randomized locations on the constellation plane to enhance the security during OFDM data transmission. The proposed dynamic mappings are performed using constellation-shifting mapping, dimension-constrained mapping and circular QAM mapping. The secure mapping schemes are demonstrated and compared in terms of optical OFDM transmission and data security performances. High-level security is achieved with huge key space, due to the introduction of hyper digital chaos in multi-fold dynamic QAM mappings.