How to assemble different restoration scheme in multi-layer networks effectively is a sticking point to survivability of ASON. Among kinds of multi-layer restoration problems, failures locating is the primary one to be solved. Therefore, fast failures locating scheme is proposed in this paper. The main idea of this restoration scheme is that optical layer communicated with control layer dynamically and the restoration process of optical layer and control layer is mutually exclusive. When a new link is established in control layer, the optical layer’s nodes whose related links is used by this new link will recode the two neighbor nodes of this new link. This information is updated online. Thus, when optical layer find failure, the related nodes can transfer the failure message to the corresponding nodes on control layer immediately. Time parameter was set to start different restoration in different layer of networks. Thus, responsibility of optical layer and control layer is clear. Confusion that may be caused by multi-layer restoration was settled.
A novel restoration scheme, Parted Path Shared Restoration (PPSR), was proposed in this paper. The major idea of PPSR is the strategy of 'parted disposal'. PPSR keeps the advantage of Path Based Shared Restoration (PBSR) in utilization of capacity. In addition, restoration time of PPSR is much less than that of PBSR. Furthermore, a satisfaction function was proposed to estimate the performance of PPSR. This function takes the utilization of capacity and restoration time into a harmonious and uniform frame. Through theoretical analysis and computer simulation, the performance of PPSR was demonstrated.
We present novel linearization methods for both of single pulse system and single-channel chirped return-to-zero (CRZ) system with the linearization assumption. Both of them show that the Gaussian fit is a good approximation over about two orders of magnitude, but deviate strongly at low probability densities. Linearization allows us to efficiently and accurately compute eye diagrams and bit error rates (BERs) without the use of Monte-Carlo simulations and allows us to greatly increase the accuracy at small BERs at a fraction of the computational cost. We compare these results to the standard Monte-Carlo simulation technique and find that they are agreed very well.
The progress of the mesh networks technology makes optical networks more complex. An adverse result is the increased network vulnerability. It’s difficult for current methods of centralized restoration to deal with the problem mentioned above. A novel survival scheme, virtual nodes scheme, is proposed in this paper. The character of network topology is considered as an important factor in this scheme. The major idea of this scheme is dividing network into some subnets, which are named as virtual nodes, and different survival approaches are adopted within each virtual node and among virtual nodes. Each virtual node not only can dispose the interior failures independently, but also can settle faults collaborating with other virtual nodes. Compared with current survival schemes, which regard each node or link as a manageable object, virtual nodes scheme take each virtual node as a manageable object. Virtual nodes scheme can find failures and restore rapidly. In addition, utilization of capacity is optimized within each virtual node. Therefore, total capacity of network is distributed efficiently. Realization of virtual nodes scheme is explained in this paper. Through theoretical analysis and computer simulation, the performance of this new scheme is demonstrated.