Adaptive QoS routing in dynamic wavelength-routed optical networks

In transparent DWDM (Dense Wavelength Division Multiplexing) networks, high blocking rate of lightpaths due to unsatisfactory BERs (Bit Error Rates) can become a major traffic bottleneck. Most of the existing routing schemes have focused on reducing the call rejection rate that is caused by wavelength exhaustion on the assigned routes, without considering the inferior network BER performance that these schemes often produce. In this paper, we propose a dynamic AQoS (Adaptive Quality of Service) routing algorithm, which assigns routes based on real-time Q factor measurements collected from devices. Not only is it BER-friendly, the incorporated CLC (Constrained Least Congested) approach in route selection makes our algorithm wavelength-efficient as well. AQoS routing can work seamlessly with variable data rates and heterogeneous device characteristics. More importantly, it handles non-uniform networks and state changes in a much more flexible way than traditional schemes. Simulation results show that our routing algorithm gives the best overall performance in all tested scenarios.