Multi-granularity switch technologies decrease the control complexity and cost of optical cross-connects (OXCs) by employing waveband and fiber routing techniques. In this paper, we study the routing and resource assignment problem in multi-granular optical networks. A novel integrated multi-layer routing and resource assignment algorithm named Dynamic Minimum Weight (DMW) is proposed. With the DMW algorithm, waveband tunnel allocation problem and wavelength channel establishment problem can be settled simultaneously. Based on the proposed DMW algorithm, the network performance with different multi-granular OXC architectures are evaluated by simulation. The simulation results also demonstrate the effectiveness of the proposed DMW algorithm.
This paper studies the routing and wavelength assignment (RWA) problem in wavelength-routed all-optical networks with dynamic traffic demand. As well known, the performance of network restoration strongly depends upon the routing and rerouting policies. In this letter, we comprehensively analyzed the restoration performance under two main alternate dynamic routing algorithm, LLR(Least Loaded Routing) and FPLC(Fixed-Paths Least-Congestion routing), and two
rerouting policies, based on K-path backup or Dijkstra algorithm. Through modelling and simulation, we compute the restoration efficiencies of four combinations on the NSFNET T1 backbone network, with different traffic load. The numerical simulation result shows that the rerouting policy based on Dijkstra algorithm has improved more 10%-20% performance than the rerouting policy based on K-path backup. The LLR and FPLC routing algorithm achieve the same performance by and large when the same rerouting policy is used.
Due to easy realization and high bandwidth utilization, SDH/WDM technology becomes the important way to carry IP traffic over the backbone network. On the other hand, the feature of the data traffic which is much different from the voice traffic is dynamic, burst and self-similar, and many proofs show that the self-similar traffic can lead to some adverse effects on the network performance due to the property of long-range dependence (LRD). For this reason it is widely recognized that self-similarity of the traffic is a significant problem as far as network engineering is concerned. So any reduction in the degree of self-similarity will be greatly beneficial. One possible strategy for mitigating the deleterious effects of the self-similarity is to reduce the burstiness of the input traffic through traffic shaping function at the edge nodes. According to this scheme, in this paper, we present a new self-similar traffic shaping mechanism with QoS in transport networks, called double threshold algorithm (DTA). Simulation results show that the proposed mechanism can effectively reduce the degree of input self-similar traffic, and performs better in the terms of network packet-loss rate and blocking probability than the non-traffic shaping schemes. At the same time it guarantees good quality of service.
This paper studies PMD compensation problems in the optical communication. In an adaptive compensation process of a practical PMD compensator, three main parts are included: an equalizer, a detection part and an algorithm. In order to achieve faster and simpler, particle swarm optimization (PSO) algorithm was introduced to this process. Although the original PSO algorithm is easy to trap into sub-optima, we proposed a new modified PSO to avoid sub-optima but keep the simplicity at the same time. This is the first time to introduce the conception of collision into PSO arithmetic, so it is called collision PSO. Through the numerical simulation, this proposed method showed the better result than the original PSO methods.
This paper studies the routing and wavelength assignment (RWA) problem in wavelength-routed all-optical networks with dynamic traffic demand. In this letter, we model the link state transition as a birth and death process. With the proposed Markov model, the path blocking probability can be determined based on the current link state and the potential link load information, and then, we establish lightpath on the least congested route. The simulation result shows that compared with other adaptive routing algorithms, the proposed algorithm achieves much better blocking performance.
This paper studies wavelength converter placement problem in wavelength-routed all-optical networks with dynamic traffic demand. We propose an analytical model to determine path usage probabilities for different routing policies and calculate the transit traffic for each node to evaluate the suitability of placing a converter at that node. With this, a heuristic algorithm, named maximum transit traffic (MTT), is proposed. Simulation results demonstrate the effectiveness of the proposed MTT algorithm.
All-optical wavelength division multiplexing (WDM) networks are the most promising candidates for the next generation wideband backbone networks. An approach to improve wavelength utilization is to allow multiple sessions share the bandwidth of a wavelength, so time division multiplexing wavelength routed networks are proposed. This paper studies the routing, wavelength and time slot assignment problem in such time-space switched networks with multi-rate traffic. We analyze the problem with a trunk-channel model, and propose an adaptive routing and trunk assignment algorithm. The effectiveness of the proposed algorithm is demonstrated by simulation.