Physical layer signal encryption using digital chaos in OFDM-PON

Fiber optical network offers higher data rate and larger capacity transmission, however the security issues are becoming a big concern. Digital chaos is capable of providing a huge key space for data encryption in physical layer, to enhance network security during high-speed data transmission. We will review the recent progress on security enhancement via the implementation of digital chaos for high-speed signal encryption, especially in orthogonal frequency-division multiplexing passive optical network (OFDM-PON). As examples, we will focus on the recently-proposed two novel security schemes using chaotic signal scrambling: partial transmit sequence (PTS) and selected mapping (SLM). It has been shown that, the digital chaotic schemes not only guarantee the network data security against malicious eavesdropping or exhaustive attacks, but also simultaneously improve the transmission performance. This is due to the significantly reduction in the peak-to-average power ratio (PAPR) of the OFDM signals via PTS or SLM. Experimentally, encrypted data transmissions of 8.9Gb/s 16QAM OFDM signals are demonstrated over 20km standard singlemode fiber (SSMF) using chaotic PTS and SLM approaches.