An effective routing strategy through impairment-aware RWA in transparent optical network

In this paper, a dynamic impairment-aware routing and wavelength assignment (RWA) algorithm is proposed to efficiently provide signal-quality-guaranteed connections and achieve lower blocking probability in all-optical wavelength division multiplexing (WDM) network with high speed optical channel. In the all-optical network, optical connection is set up to carry data signal from source node to destination node without optical-electrical-optical (OEO) conversion via all-optical lightpath. During the travel, the signal transmitted along the lightpath must pass through a number of optical components, such as optical amplifiers, optical crossconnect switches (OXCs) and fiber segments. While the optical signal propagates to the destination, the impairment would accumulate along the all-optical lightpath with these components, which makes the quality of signal degrade continuously. When the impairment accumulation comes to a serious degree, the bit-error rate (BER) would be too high to be acceptable in the destination receiver, the good quality of service for a connection request could not be provided in physical layer and the connect request would be rejected in control plane because of impairment accumulation. Therefore new techniques in both physical layer and network layer are necessary for decrease the influence of impairment accumulation. Here we investigate a new dynamic RWA algorithm to lower blocking probability of connection. By jointly consideration of both available wavelength and wavelength dependent impairments, the routing weight functions can be dynamically updated to accommodate between wavelength blocking and physical layer blocking. Simulation results indicate that the proposed algorithm can achieve lower blocking probability.