Conventional tree-based optical code division multiple access (OCDMA) systems do not provide any protection between optical line terminal and optical network units. This makes the entire OCDMA system significantly vulnerable to failures. This paper proposes a novel dual-ring spectral amplitude coding (SAC) OCDMA system, which consists of a single ring at the feeder level and two semi-rings at the distribution level. Analysis shows that the proposed system immediately detects and restores the flow of affected traffic and ensures survivability of the entire network. Moreover, comparison of the proposed system with exiting protection schemes shows that the proposed dual-ring SAC-OCDMA system provides desirable availability, 99.9995%, with minimum expenditure through simple architecture and simultaneous protection against failures at both feeder and distribution rings.
