The Research On High-Speed Chaos-Based Secure Passive Optical Network

Wavelength division multiplexed passive optical network (WDM-PON) has been considered as one of the most suitable candidates for the next generation broadband optical access network, for its attractive merits, such as broadband capability, economical cost, and low energy consumption, et al.. Nevertheless, with the sharp increasing of the communication network consumer number and the rapid development of network capacity, the security of optical access network has turned to be one key issue that would limit the development of communication networks. Up to present, most of the security solutions are focused on the data encryption at the media access control (MAC) layer or the higher layers. Under such a scenario, since the fiber link is vulnerable to kinds of attacks, it is valuable to enhance the security of physical layer of optical access network to guard the privacy of customers. In the last decade, the all-optical chaotic communication has been extensively studied, since that the broadband optical chaotic signal can well hide the message that is modulated into it, which can improve the security of the physical layer. The main research works are listed as follows:A physical-enhanced secure passive optical network (PON) based on chaos synchronization is introduced and numerically demonstrated. In this scheme, the chaotic output of an external-cavity semiconductor laser is used as the transmission carrier in both downstream and upstream directions, the chaos modulation technology is used to encrypt the downstream data, and the multiplexed subcarrier-modulation technology is adopted for the upstream transmission. Simulation results demonstrate that both the downstream data and the upstream data encrypted into the chaotic carriers can be successfully decrypted while the security can be maintained at a high level. Based on this, a physical security-enhanced wavelength division multiplexed passive optical network (WDM-PON) based on chaos synchronization between twin laser pairs is introduced. We numerically demonstrate that with sufficient wavelength spacing, a high quality chaos synchronization between the chaotic carriers with identical wavelength can be maintained, which enables the proposed WDM-PON to afford multichannel chaotic communications at high bit rates in both the downstream and upstream directions. The security of the physical layer can be greatly enhanced.A novel secure passive optical network (PON) configuration jointly based on the chaos synchronization of wavelength division multiplexed chaotic signals and the subcarrier modulation multiplexing is introduced. For the sake of simplicity, we take the case with two wavelengths and two subcarriers for instance, to demonstrate the concept of the proposed WDM-SCM-PON. The numerical results demonstrate that with proper selection of the wavelength spacing, high quality chaos synchronization can be achieved on each wavelength, and each wavelength can afford several OLT-ONU transmissions by properly allocating the frequency spacing of subcarriers. Based on this, a symmetric 24 Gbit/s (12 Gbit/s on each wavelength) chaotic WDM-SCM-PON is achieved. The BER for each OLT-ONU transmission is smaller than 10-6, as long as the bit rate is lower than 6 Gbit/s.