Automatic Protection, Restoration, and Survivability of Long-Reach Passive Optical Networks

The long-reach passive optical network (LR-PON) is receiving significant research attention due to its potential in delivering future bandwidth intensive services to a significantly higher number of customers at a lower unit cost of bandwidth. Carrying substantially higher traffic over increased distances as compared to conventional PONs, the survivability of these networks is a key feature that must be addressed to ensure end-to-end network reliability. Further, as these networks are optically amplified to extend its coverage, measures to detect and remove hazardous high power exposure at the fiber break are also critical. Here, we propose, experimentally demonstrate, and characterize a simple automatic protection switching scheme that exploits the use of a highly-sensitive and fast-response protection module to achieve traffic diversion to the protection path within 12 ms of failure detection. The protection module also provides an additional flexibility of activating amplifier shutdown within 2 ms of failure detection, thereby removing the hazard at the fiber break. We also perform numerical analyses of LR-PON survivability based on the probabilistic nature of fiber link failures, for conventional traffic as well as for peer-to-peer sharing over the LR-PON. Our results highlight that the level of improvement in survivability from optical protection in an LR-PON is dependent on the probability link failure of each stage of the network.