Optical-fiber-based backhauling offers a future proof solution to handle rapidly increasing traffic in wireless access networks and outperforms other existing backhauling technologies, such as microwave and copper, in terms of capacity, scalability, and sustainability. However, the deployment cost of fiber infrastructure is relatively high and it may be difficult to provide a cost efficient and flexible protection strategy for a fiber backhauling network. Considering that protection is very important to avoid service interruption in a high-capacity mobile backhauling network, within DISCUS KTH proposes a hybrid fiber and microwave protection scheme for mobile backhauling based on a passive optical network (PON). The proposed reliable architecture is compatible with any wavelength division multiplexing (WDM)-based PON, e.g., pure WDM PON and a hybrid time and wavelength division multiplexing (TWDM) PON, offering high flexibility and relatively low deployment cost. The backup for the feeder fiber is provided by dual homing based on key idea from DISCUS for long reach PON, while the protection of the distribution section can be established via a microwave connection between two base stations in case high reliability performance is required, e.g., for macrocells covering large service areas. KTH has carried out an extensive assessment of our approach in terms of connection availability, failure impact, complexity, and flexibility in providing resiliency. We also show a comparison with other existing solutions. The evaluation results confirm that our scheme can achieve relatively high flexibility and reliability performance while maintaining low complexity compared with the existing approaches.
Yanpeng Yang, Ki Won Sung, Lena Wosinska, and Jiajia Chen, “Hybrid Fiber and Microwave Protection for Mobile Backhauling”, IEEE/OSA Journal of Optical Communications and Networking, Vol. 6, Issue 10, pp. 869-878 (2014).