Frequency-hopping communication with physical-layer chaos encryption

We propose and numerically demonstrate a scheme that integrates frequency-hopping (FH) communication with physical-layer chaos encryption. In this scheme, chaos synchronization between twin semiconductor lasers driven by a common digital signal is utilized to generate synchronous chaos after optoelectronic conversion and post-processing. A binary frequency-shift keying (2FSK) message at the transmitter is then masked by the chaos carrier and FH modulated to create a hopping signal with embedded chaos encryption. The chaos-encrypted hopping signal is transmitted through a wireless channel influenced by additive white Gaussian noise to the receiver, where it is decrypted using FH demodulation and the cancellation of synchronous chaos. Results show that secure transmission of the 2FSK message is achievable by legal users, even if the FH pattern is cracked by the attacker. The security is further assessed by analyzing the bit error rates for legal decryption and attack under different system parameters.