Blocking Probability in All-Optical WDM Network Using IMCA

The analysis of WDM (Wavelength-Division Multiplexing) optical network is essential to have the routed wavelength blocking probability with the conversion of wavelength using techniques. In this paper, an enhanced analytical model is proposed to evaluate the blocking performances in topology network and to improve the performances of reduction of blocking probability. The variation of probability is based on the wavelength and load used in the network. The conversion is carried out with the support of optical backbone of the inherent flexibility of the network using the proposed IMCA in Sparse-Partial Wavelength Conversion (SPWC) architecture. It reduces the number of converters significantly with efficient process and provides placement scheme of wavelength converters in the network. The proposed model utilizes the network with the assignment and routing of wavelength using dynamic process of assignment algorithm. The proposed model provides dynamic and static routing process with the range limit to have a minimum conversion for the same probabilities of blocking. The proposed system analysis and the simulation results show the better performances in faster coverage, minimum number of conversions, blocking probability improvement for high load.

Blocking Probability Based Hierarchical Storage Design in VoD Systems

In this paper, we discuss the relationship between the blocking probabilityand the configuration of storage hierarchy in a Video on Demand ( VoD) server using the queueingmodel we propose. With this model, the optimal configuration of the storage system can be obtained .

Impact of Wavelength-Routed Network Physical Topology on Blocking Probability Using a Dynamic Traffic Growth Model

We investigate the impact of network topology on blocking probability in wavelength-routed networks using a dynamic traffic growth model. The dependence of blocking on different physical parameters is assessed.

Blocking probability analysis model for flexible spectrum optical networks

Compared to the traditional wavelength division multiplexing （WDM） optical networks with rigid and coarse granularities, flexible spectrum optical networks have high spectrum efficiency, which can support the service with various bandwidth requirements, such as sub and super channel. Among all network performance parameters, blocking probability is an important parameter for the performance evaluation and network planning in circuit^based optical networks including flexible spectrum optical networks. We propose an analytical method of blocking probability computation for flexible spectrum optical networks in this letter through mathematical analysis and theoretical derivation. Two blocking probability models are built respectively based on whether considering spectrum consecutiveness or not. Numerical results validate our proposed blocking probability models under different link capacity and traffic loads.

MULTI-DIMENSIONAL MARKOV CHAIN–BASED ANALYSIS OF CONFLICT PROBABILITY FOR SPECTRUM RESOURCE SHARING

In this paper, we consider the optimal problem of channels sharing with het-erogeneous traffic （real-time service and non-real-time service） to reduce the data conflict probability of users. Moreover, a multi-dimensional Markov chain model is developed to analyze the performance of the proposed scheme. Meanwhile, performance metrics are derived. Numerical results show that the proposed scheme can effectively reduce the forced termination probability, blocking probability and spectrum utilization.

Survivability evaluation for networks carrying complex traffic flows

The capability of a system to fulfill its mission promptly in the presence of attacks,failures,or accidents is one of the qualitative definitions of survivability.In this paper,we propose a model for survivability quantification,which is acceptable for networks carrying complex traffic flows.Complex network traffic is considered as general multi-rate,heterogeneous traffic,where the individual bandwidth demands may aggregate in complex,nonlinear ways.Blocking probability is the chosen measure for survivability analysis.We study an arbitrary topology and some other known topologies for the network.Independent and dependent failure scenarios as well as deterministic and random traffic models are investigated.Finally,we provide survivability evaluation results for different network configurations.The results show that by using about 50%of the link capacity in networks with a relatively high number of links,the blocking probability remains near zero in the case of a limited number of failures.

COOPERATIVE DIRECTIONAL INTER-CELL HANDOVER SCHEME IN HIGH ALTITUDE PLATFORM COMMUNICATIONS SYSTEMS

A novel Cooperative Directional inter-cell Handover Scheme(CDHS) for High Altitude Platform(HAP) communications systems is proposed,in which the handover target cell and the two cells adjacent to this handover target cell work cooperatively to exploit the traffic fluctuation to improve handover performance.Users in the overlap area of the overloaded handover target cell will be forced to handover directionally before their optimal handover boundary in order to free up resources for the handover calls which would otherwise be dropped due to the shortage of resources and queue time out.Simulation results show that the handover call dropping probability is greatly reduced(at least 60%) compared with the general queue handover scheme,with little performance reduction to the call blocking probability,and the Not in the Best Cell(NBC) average time is only increased moderately.Moreover,an optimal cell radius can be achieved for a specific platform speed by minimizing the unified system performance,which is the linear combination of the handover call dropping probability and the NBC average time.

Proactive Connection Recovery Strategy with Recovery Time Constraint for Survivable Elastic Optical Networks

This paper presents a halfway signaling exchange shared path protection(HSE-SPP)on the backup route for a fast connection recovery strategy.In the proposed HSE-SPP,a pre-assigned intermediate node on the backup route is chosen for signaling exchange.When connection fails,source and destination nodes simultaneously generate backup connection setup messages to the pre-assigned intermediate node on the reserved backup route.At the intermediate node,signaling process occurs,and acknowledgment is generated for data transmission to the respective end nodes.Consequently,connection recovery time by applying HSE-SPP becomes very low.Simulations are performed for network parameters and results are verified with existing strategies.The average recovery time(RT),bandwidth blocking probability(BBP),bandwidth provisioning ratio(BPR),and resource overbuild(RO)ratio of HSE-SPP for ARPANET is 13.54 ms,0.18,3.02,0.55,and for dedicated path protection(DPP)are 13.20 ms,0.56,6.30,3.75 and for shared path protection(SPP)22.19 ms,0.22,3.23,0.70 respectively.Similarly,average RT,BBP,BPR and RO of HSE-SPP for COST239 are8.33 ms,0.04,1.64,0.26,and for DPP 4.23,0.47,3.50,2.04,and for SPP 11.81,0.08,1.66,0.27 respectively.Hence,results of the proposed strategy are better in terms of RT,BBP,BPR,and RO ratio.

Random Channel Allocation Scheme for SDMA Systems

A random allocation scheme for SDMA systems is proposed with a goal of more efficient dynamic allocation. Based on theoretical analysis and derivation, the blocking probability of the proposed scheme is calculated and compared with those of the ftrst duplicate （FD） and duplicate last （DL） schemes with different state-independent probabilities （p,） of acquring a dupicate channel suecessfully and 5 resources; moreover, a more realistic performance analysis of the random scheme is made with state-dependent ps in the SDMA/CDMA environment. The results show that the random scheme has a similar allocation pefformace to the FD and DL schemes, but is simpler than them in computation and scheduling.

An Approach to Calculate the Blocking Probability of Multistage Link System Using the Minimum Pathset

The structure of multistage link systems and the calculation of their blocking probability arediscussed in the paper. The characteristics of SPC digital switching network are specially outlined. Thenby defining the minimum pothset used in network graph, a general algorithm is developed to calculate theblocking probability of a complex network. Compared with traditioanl methods for calculating the block-ing probability, the algorithm derived in this paper is more sirnple, more effective and more easily realizedon computer, and is well worthy of being used practically.

New bandwidth algorithmand its performance analysis in integrated service network

Because of no strict expression of calculating call blocking probability （CBP） in the solution procedure of virtual-path bandwidth allocation problem, the process of calculating bandwidth through CBP and traffic load adopts the iteration algorithm in common, which is an inverse process of calculating CBP through traffic load and bandwidth. It limits computing speed by a long way because of including recursion. An approximate algorithm of bandwidth is presented. We compare the performance of this algorithm with that of another classical algorithm and conclude that the former makes a great increase in speed with little error about 2 %.

New degradation call admission control for increasing WCDMA system capacity

Propose a new degradation call admission control（DCAC）scheme, which can be used in wideband code division multiple access communication system. So-called degradation is that non-real time call has the characteristic of variable bit rate, so decreasing its bit rate can reduce the load of the system, consequently the system can admit new call which should be blocked when the system is close to full load, therefore new call＇s access probability increases. This paper brings forward design project and does system simulation, simulation proves that DCAC can effectively decrease calls＇ blocking probability and increase the total number of the on-line users.

PRODUCT IMAGE RETRIEVAL BASED ON CO-FEATURES OF THE OBJECT

In this paper, we propose a product image retrieval method based on the object contour corners, image texture and color. The product image mainly highlights the object and its background is very simple. According to these characteristics, we represent the object using its contour, and detect the corners of contour to reduce the number of pixels. Every corner is described using its approximate curvature based on distance. In addition, the Block Difference of Inverse Probabilities (BDIP) and Block Variation of Local Correlation (BVLC) texture features and color moment are extracted from image's HIS color space. Finally, dynamic time warping method is used to match features with different length. In order to demonstrate the effect of the proposed method, we carry out experiments in Mi-crosoft product image database, and compare it with other feature descriptors. The retrieval precision and recall curves show that our method is feasible.

Improved wavelength decomposition approach for computing blocking probabilities in WRONs

Wavelength decomposition approach has been proposed to compute blocking probability （BP） of fixed routing in wavelength-routed optical networks （WRONs） without wavelength conversions. By means of wavelength decomposition, a WRON can be regarded as a set of different layers （colors）, in which blocked traffic in one layer is overflowed to another layer. A novel iterative scheme is put forward in case of t3P matching used to characterize the overflow traffic from one layer to another in this paper. Furthermore, the analysis of BP based on the improved wavelength decomposition approach is derived and results show that it yields higher calculation accuracy.

Crosstalk-aware RCSA for spatial division multiplexing enabled elastic optical networks with multi-core fibers

In this Letter, we propose two crosstalk-aware routing, core, and spectrum assignment （CA-RCSA） algorithms for spatial division multiplexing enabled elastic optical networks （SDM-EONs） with multi-core fibers. First, the RCSA problem is modeled, and then a metric, i.e., CA spectrum compactness （CASC）, is designed to measure the spectrum status in SDM-EONs. Based on CASC, we propose two CA-RCSA algorithms, the first-fit （FF） CASC algorithm and the random-fit （RF） CASC algorithm. Simulation results show that our proposed algorithms can achieve better performance than the baseline algorithm in terms of blocking probability and spectrum utilization, with FF-CASC providing the best performance.

Recovery schemes for different distributed connection management in generalized multi-protocol label switching networks

As the wavelength division multiplexing （WDM） technology matures and the demands for bandwidth increase, survivability becomes more and more important in generalized multi-protocol label switching （GMPLS） controlled intelligent optical networks （IONs）. There are great interests to study the performance of restorability under one certain connection management strategy. And studies in the problem of providing recovery from link failures under two different resource reservation schemes, forward reservation protocols （FRPs） and backward reservation protocols （BRPs）, are presented. They are examined from the point of view of connection blocking probability, restorability and average recovery time. The two different connection management schemes and the survey of different recovery schemes are first presented. The performance of these recovery strategies is analyzed and compared both through theoretical analysis and simulation results. The main stressed idea is that using BRPs gives the best performance in terms of restorability and blocking Drobability in restorable GMPLS networks.

Distributed Reservation Protocol and QoS Method in WR-OBS System

Starting from centralized control model used in wavelength routed optical burst switching network, a distributed control model and correspondent wavelength resource reservation protocol are proposed in this paper. Two Quality- of-Service （QoS） methods, Based on the resourcereservation protocol, are discussed. Also, computer simulation is implemented to investigate the performance of the newly proposed reservation protocol and QoS methods. Simulation results demonstrate that the QoS methods can efficiently provide different level service quality to traffic＂ with different priorities. Furthermore, performances of the two QoS methods are compared concerning the QoS distinguished level, burst lost probability and implementation difficulty. It has been shown that the newly propose reservation protocol and QoS methods is a high qualified candidate for the future OBS networks.

A New Dynamic Channel Allocation Scheme for Microcellular Systems

A new Distributed Dynamic Channel Allocation (DDCA) algorithm named Combined DDCA is proposed in this paper.In this algorithm, each base station selects channels by learning through past experience of channel usage together with CIR measurement. Computer simulations are used to evaluate system performances. Performances are evaluated in two criteria, blocking probability and interaction probability. Comparisons with other DDCA algorithms have been carried out to validate the proposed algorithm.

Wavelength pre-assignment collision schedule for wavelength-routed optical networks

A novel wavelength assignment scheme called the wavelength pre-assignment collision schedule （WPCS） is proposed for wavelength-routed networks. The WPCS pre-assigns the wavelength at the forward detection phase, and schedules the potential collision by priority. The potential collision is scheduled at the forward detection phase and the blocking of the wavelength assignment is reduced. Simulation is conducted with several other existing schemes. The numerical results show that WPCS performs better than other schemes in blocking probability under various traffic conditions.

Design of a practical optical cross-connect with limited-range wavelength conversion

The architecture of and the corresponding control algorithm for a devised optical cross-connect, limited- range wavelength converision wavelength interchangeable cross-connect （L-WIXC）, are presented. The performances of L-WIXC including blocking probability, switching time, and throughput are simulated. Cost comparison with wavelength selective cross-connect （WSXC） and WIXC is calculated. Key optical parameters, such as crosstalk, eye diagram, bit error rate, and linear Q factor, are measured and discussed.