Hybrid waveband/wavelength switching in intelligent optical networks is gaining more and more academic attention. It
is very challenging to develop efficient algorithms to efficiently use waveband switching capability. In this paper, we
propose a novel cross-layer routing algorithm, waveband layered graph routing algorithm (WBLGR), in waveband
switching-enabled optical networks. Through extensive simulation WBLGR algorithm can significantly improve the
performance in terms of reduced call blocking probability.
Checking the great generator's vibration online is difficult because of its strong electric and magnetic field so it needs had better no metal in the sensor. We introduce a method of measuring vibration by using FBG and demodulating it by blazed grating and it doesn't use any metal. We present the design method and the theory of
demodulation. The results of the experiment show that the vibration amplitude of the exciter matches the detected signal under the stable frequency. The experiment also successfully separated the temperature shift and vibration signal.
A novel waveband switching node architecture is proposed using tunable optic filters for arbitrary waveband add/drop. The simulation results show this new architecture achieves lower blocking probability and reduce the scale of ports at switch fabric.
Waveband switching routing is a new problem for research community. It is has some different with the routing of wavelength assign problem. In this paper, we propose a new ideal for agent based Waveband switching network construction. Primary simulation shows that in this way complexity of virtual network topology and blocking probability reduced.
Recently, performance evaluation of TCP over Optical Burst-switched Network (OBSN) has drawn more and more attention, but previous work mainly focused on single TCP flow or static traffic model. In this paper, performances of different TCP implementations deployed in OBSN under dynamic competing traffic are investigated.
In this paper a novel hybrid WDM/TDM optical access network architecture and its media access control (MAC) alogrithm is proposed. Extensive simulations are conducted and the results show that the algorithm can provide determinate delay bound for each flow, possesses throughput fairness and decreases the packet delay of low
In this paper, a traffic-grooming problem for multi-granularity traffic of SDH/SONET in WDM grooming mesh networks is investigated. Our objective is to improve the throughput of SDH/SONET WDM mesh networks. We propose a heuristics algorithm to solve this problem. The performances of this traffic grooming heuristics algorithm are evaluated in WDM grooming networks. Finally, we presented and compared the simulation results of this methodology in dynamic traffic grooming WDM mesh networks with that of other methodologies.
In this paper, we proposed two waveband switching algorithms: Minimal Hop Routing (MHP) and Maximal Overlapped Routing (MOP). The differences between them are the weight of link in the layered graph at the waveband and wavelength planes. In MHP algorithm, the weight of links at waveband and wavelength planes are the same, but MOP assigns lower weight to them at the waveband plane than that at the wavelength plane. We conducted extensive simulations with dynamic traffic patterns in the mesh network topology. We evaluated the performance of the proposed algorithms in terms of blocking probability and the number of OXCs port with waveband algorithms of MOP, MHP and RWA algorithm of shortest path routing (SPR). Simulation result shows that waveband algorithm has low blocking probability, and less number of ports is used.
As a promising solution for next-generation broadband access networks, EPON could provide full-service access such as voice, video and data applications. However, EPON’s standard IEEE 802.3ah does not specify a particular supporting mechanism to guarantee QoS and priority requirements of various services, allowing it to be vendor specific. Meanwhile, how to segregate user traffic to guarantee security, remains unsolved. This paper creatively introduced the 802.1Q VLAN (Virtual Local Area Network) technique into the EPON system to solve these problems. Firstly, a brief introduction of EPON system is given. Secondly, the VLAN solution is presented in detail. Unlike VLAN mapping according to port or MAC in Gigabit Ethernet, EPON’s VLAN mapping is based on LLID tag. At last, OLT MAC layer design is given and FPGA implementation is described in detail. Detailed simulation experiments have been conducted to study the performance and validate the effectiveness of the proposed mechanism.
In Optical burst switching (OBS) networks, one important issue is how the performance will be affected by burst assembled from packets. In this paper, we study the fundamental statistic properties of Possion and Pareto traffic, such burst length distribution, inter-arrival time distribution and the switching performance with different aggregation schemes. The results show that the traffic will approach the Gaussian distribution of both kinds of traffic, but the aggregation operation has little effect on the heavy tail of Long Range Dependent traffic. The aggregation algorithm based on aggregation time degrades the loss performance of burst switch because burst arrivals easily concentrate a moment at the period of aggregation time window.
A new optical label scheme called Common optical SCM (Subcarrier Multiplexing) label method is proposed. The label paths are consisting of multiplex SCM paths with SCM/WDM technology, which separate from the data wavelength paths. These label paths are parallel and shared for any data wavelength path. We analyzed the modulation and transmission of SCM label channels and compared the bandwidth efficiency and switching performance of main several optical label schemes. The results show that because of no guard between label and data packets the bandwidth efficiency increases and the operation complexity decreases in common optical label schemes and multiple shared parallel SCM label channels can decrease the block probability of label packets.
A new flexible broadcast optical switching structure (FBOSS) using tunable optical splitter is proposed. FBOSS supports both point-to-point and point-to-multipoint (broadcasting) connections, and any input optical signal can be broadcasted to any number of output optical ports without extra optical power loss. Its flexibilities of the optical port and optical wavelength help to enhance the capability of switching.
In this paper, a traffic-grooming problem for multi-granularity traffic of SDH/SONET in WDM grooming mesh networks is investigated. We propose a path select routing algorithm to solve this problem. The performances of this traffic grooming path select routing algorithm are evaluated in WDM grooming networks. Finally, we presented and compared the simulation results of this algorithm in dynamic traffic grooming WDM mesh networks with that of other algorithms.
In this paper, the objective was optimizing the port number with dynamic traffic grooming of SDH/SONET WDM mesh networks to give useful referenced data to networks design and the cost control of networks. The performances of different path select routing algorithms were evaluated in WDM grooming networks by considering traffic of different bandwidth requests. Finally, the results were presented and compared with in distributed-controlled WDM mesh networks.
Constraint-based routing algorithms are a key component to meet various requirements subjects to a set of constraints for bandwidth requests in the GMPLS-based optical networks. The purpose of GMPLS control plane is to provide an intelligent automatic end-to-end label switched path provisioning/signaling framework to support arbitrary bandwidth traffic. We developed a detailed simulation platform for an IP-over-MPLS-over-WDM network, so that extensive simulations are carried out to evaluate the network performance of various routing algorithms and routing strategies with RSVP-TE or CR-LDP signaling protocol in GMPLS-based IP/MPLS optical networks in terms of blocking probability. The simulation results show that the signaling protocol improves the network performance more significantly than multi-fiber configuration and CR-LDP signaling mechanism outperforms RSVP-TE in all cases. Furthermore, the LCF routing strategy also has better performance than LCL strategy.
In this paper, the dynamic distributed traffic-grooming problem in WDM optical mesh network is investigated. We give the proposal of the number optimization of wavelengths and ports are evaluated in a class of IP/WDM distributed nteworks. We presented and compared the performances of dynamic distributed traffic grooming in regular and irregular optical mesh networks, and give the optimized number of wavelengths and ports in different network condition.
A new loop output buffer architecture for optical packet switching is proposed. It is consisted of multiplex FDL loops, which are divided into k stages by k (M+1) x (M+1) switches. Using this architecture, a few FDL loops can provide large optical memories and get good packet-loss performance, and the delay performance can be improved by adding switches and buffer scheduling.
A novel all-optical packet switching is presented. Adopting optical-controlled optical switch and multi-wavelength optical label technology, all the extraction of optical packet header, recognizing of route information and control of optical switch matrix can be processed in optical domain without O-E/E-O conversion. In this switching, the header label pulses are separated to different optical paths to control the optical-controlled optical switch matrix. According to different sequence and different wavelength of the header pulses, the different optical routes can be established, and a kind of all-optical packet switching is achieved.
A novel multistage optical cross-connect (OXC) that combined the advantages of three technologies of Space Division Switching (SDS), Wavelength Division Switching (WDS), and Optical Time-Division Multiplexing (OTDM) has been proposed. The structures of the first and second stages of a 2 X 2 and a 4 X 4 OXC have been presented. By means of the splitter and delivery (SAD) switch, it is cost-effective and fully modularized and very convenient to scale to n X n OXCs suitable for large-scale backbones.
n this paper, we propose a G1VIPLS-based unified traffic engineering scheme in optical networks to cooperate at both optical layer and IP/MPLS layer achieving high efficiency of resource utilization. In WDM networks, end-to-end all-optical paths, called lightpath, can be setup between two edge optical routers. The set of lightpath comprise of the logical topology of optical networks. In IP/MPLS layer, a LSP is established on the logical topology. With the traffic increasing or decreasing, it is expected that the logical topology can adapt to traffic changes. When the traffic in a lightpath increases and becomes extremely heavy, allotting a new lightpath can partition some traffic and relieve the congestion. On the contrary, when the bandwidth utilization in a lightpath is very low, the lightpath may be released to free up its occupied resources. Based on this idea, a topology-adaptive scheme is proposed and two adjustable thresholds are introduced which are employed to control the frequency of lightpath setup or release. Finally, several key issues in unified traffic engineering are presented
Optical Burst Switching combines the advantages of circuit switching and package switching, and it can improve the efficiency of system resource with high speed transmission and Qos. Now the rationale of OBS has been discussed a lot, and many schemes have been given. While there are still some key problems need to be resolved, such as in the model of IP over WDM, how to assemble the IP packages into burst that will be transmitted in the optical networks; and how to set the offset time between payload and its control package. In this paper, we provide a part randomized offset-time method to calculate the offset time upon the basis of: the network condition of the optical path that the payload will pass, the shaping scheme which is introduced to reduce the drop probability. At the same time, although there are many factors should be considered when setting the offset time, too sophisticated algorithm will be discarded. Because our ultimate end is to get equilibrium between the control complexity and bandwidth efficiency even some redundancy will be introduced in this method. We also consider a balance between end-to-end delay and blocking probability introduced by the new offset-time determination algorithm. At last, we will analyze the improvement in the network performance if the offset time has been set properly, especially when associated with delayed reservation technology.
The realization technology of a new kind of multi-wavelengths label optical packet switching technology is discussed. In this switching, optical header is labeled by several optical pulses at different wavelengths in the same optical communication channel band as optical payload. The optical transmitter with header generation and packet formation, receiver with data restoration and switching node with route processing are introduced. The switching principle is verified by a simplified experiment.
Wavelength-division multiplexing appears to be the solution of choice for providing a faster networking infrastructure that can meet the explosive growth of the Internet. Future networks are expected to utilize the WDM technology for optical functionalities capable of handling multi-Teragabit signals and thus the cost, therefore it is very important that the Optical cross-connects (OXCs) and optical Add-drop Multiplexers (OADMs) have performed routing and switching capacities. Optical Packet Switch (OPS) technology allows us to rapidly deliver the enormous network bandwidth. OPS offers high-speed data rate and format transparency. But there are still many technologies and key components need to solve. In this paper we propose a novel architecture for OPS using Tunable Wavelength Converters (TWC) and Fiber Delay-Lines (FDLs). We use wavelength converters and demuxes connected with several FDLs that provide different delay periods. Input wavelengths can be tuned to different ones in order to acquire different delay periods. Wavelength converters are shown to improve the traffic performance of the switch blocks for both random and burst traffic. It can also provide contention resolution solution in wavelength and time domains. This architecture improves packet switching speed and significantly decreases the use of optical switches comparing with general architecture. Finally, the simulation results show that the packet blocking can be decreased.
Optical Label Switching (OLS) is one of the practical manners of optical packet switching. It is a main research domain in optical networks. The advantage of OLS is its bandwidth efficiency and ability to support various network devices. There are a lot of practical problems need to be resolved. Today, research into OLS technology has focused on key networking and hardware issues such as high-speed optical switch, optical storage component, and network nodes source distribution optimization algorithm. The optical Label Header contains header synchronizing bits, routing address bits, etc. Header reading and rewriting includes synchronizing, routing and checking technologies. So it is the key issue in the OLS, and has very important research and application values. In this paper, a novel proposed fabric scheme was discussed to achieve the function of the header reading and rewriting. It can be applied to the high-speed header reading and rewriting to satisfy the requirements of practical applications. The fabric scheme adopts a high-speed tunable laser and wavelength converter to rewrite the header. The high-speed tunable laser is based on Grated Coupler Sampled Reflector (GCSR) structure and the wavelength converter is based on Cross-Phase Modulation (XPM) in a Semiconductor Optical Amplifier (SOA) and a Mach-Zehnder Interferometer (MZI) structure. The synchronization of the packet in the node also be discussed.
Using the feature that the gain peak wavelength only depends on the pump wavelength, the multi-pump sources and their gain peak wavelengths can be considered as the input and output variables of the single layer feed-forward neural networks, and the optimal design for multi-pumped Raman Fiber Amplifier can be converted to a optimal problem of the single layer feed-forward neural networks. With the optimal algorithm the Raman gain spectra of multi-pumped FRAs were investigated. The results show that the optimal configuring algorithm is simple and effective.
Synchronization is one of the difficult problems in realization of Ethernet PON receiver, because the bit rate is as high as 1 .25Gb/s and the receivers works in burst mode. Burst mode synchronization relates to two key techniques: ranging and phase adjustment. For these two key techniques, this paper puts forward a ranging flow for the Ethernet PON system and a novel burst mode synchronization circuit running at 1.25Gbps. Using VHDL, the algorithm and the structure of ranging could be realized, and the result of simulation is provided. The performance of the ranging flow is compared for the different collision resolution algorithm. At the same time, the feasibility and the performance of a high speed burst synchronization circuit are presented with the simulation result.
The most important feature of Raman gain spectrum is that the gain peak wavelength only depends on the pump wavelength (fixed shift about 100nm). Using the gain values of these gain peak wavelengths we can determine how to adjust power and intervals of pumps until the optimal result is made. In this paper, using the peak wavelength gain optimal method and a comprehensive model the Raman gain spectra of multi-pumped FRAs under the various conditions were investigated. The results show that controlling the pump sources power and wavelength intervals can optimize the bandwidth and flatness of gain spectrum. The optimal configuring method for the multi-pump sources of distributed FRAs is simple and effective.
Using a comprehensive model that includes pump-to-pump, pump-to-signal, signal-to-signal interaction, Rayleigh scattering and amplified spontaneous emission the Raman gain spectra of multi-pumped Raman amplifier under the various conditions were investigated. The results show that a different pump powers and pump wavelength intervals schemes are required for multi-pumped Raman amplifier. To obtain broader bandwidth and smaller gain ripple the powers of the shorter and longest wavelength pumps are needed higher power and the powers of the middle wavelength pumps should be set lower.
Optical layer networking and survivability are very important branches of the study of optical communication network. Recent standards proposals have focused on extending MPLS protocols to manage optical network resources. These proposals have concentrated on provisioning optical connections and offering restoration capability in mesh optical networks. Few papers, however, are concentrated on protection issues of backup path. By considering the protection of backup path, survivability of protection scheme will improve. This article presents a novel paradigm enhancing the existing pre-established protection schemes using Multi-Protocol Lambda Switching architecture and demonstrates local restoration and global restoration for backup path with examples. Finally, we discuss the advantages of this approach and present future work.