Routing In Dynamic Networks Research Articles

Dynamic Equilibria in Fluid Queueing Networks

Flows over time provide a natural and convenient description for the dynamics of a continuous stream of particles traveling from a source to a sink in a network, allowing to track the progress of each infinitesimal particle along time. A basic model for the propagation of flow is the so-called fluid queue model in which the time to traverse an edge is composed of a flow-dependent waiting time in a queue at the entrance of the edge plus a constant travel time after leaving the queue. In a dynamic network routing game each infinitesimal particle is interpreted as a player that seeks to complete its journey in the least possible time. Players are forward looking and anticipate the congestion and queuing delays induced by others upon arrival to any edge in the network. Equilibrium occurs when each particle travels along a shortest path. This paper is concerned with the study of equilibria in the fluid queue model and provides a constructive proof of existence and uniqueness of equilibria in single origin-destination networks with piecewise constant inflow rate. This is done through a detailed analysis of the underlying static flows obtained as derivatives of a dynamic equilibrium. Furthermore, for multicommodity networks, we give a general nonconstructive proof of existence of equilibria when the inflow rates belong to Lp.

Trust-based backpressure routing in wireless sensor networks

In this paper, we apply a vector autoregression (VAR) based trust model over the backpressure collection protocol (BCP), a collection mechanism based on dynamic backpressure routing in wireless sensor networks (WSNs). The backpressure scheduling is known for being throughput optimal. In the presence of malicious nodes, the throughput optimality no longer holds. This affects the network performance in collection tree applications of sensor networks. We apply an autoregression based scheme to embed trust into the link weights, so that the trusted links are scheduled. We have evaluated our work in a real sensor network testbed and shown that by carefully setting the trust parameters, substantial benefit in terms of throughput can be obtained with minimal overheads. Our results show that even when 50% of network nodes are malicious, VAR trust offers approximately 73% throughput and ensures reliable routing, with a small trade–off in the end–to–end packet delay and energy consumptions.

Distance Adaptive Dynamic Routing and Spectrum Allocation in Elastic Optical Networks with Shared Backup Path Protection

This paper considers distance adaptive dynamic routing and spectrum assignment (RSA) for elastic optical networks with shared backup path protection (SBPP). Efficient heuristic algorithms based on spectrum window planes are proposed for implementing distance and modulation format adaptive RSA so as to maximize spare capacity sharing among multiple protection lightpaths. A differentiated sharable frequency slot cost was also defined for the first time to more efficiently share protection resource. Network performance is evaluated in terms of bandwidth blocking probability (BBP) through simulations. The proposed SBPP technique is effective in reducing BBP and improving spectral efficiency compared to conventional SBPP schemes and 1+1 path protection. The impact of transponder tunability on bandwidth blocking performance is also evaluated to show that a limited tuning range is sufficient to achieve a BBP performance close to that with full tunability.

An Optimized Algorithm for Dynamic Routing and Wavelength Assignment in WDM Networks with Sparse Wavelength Conversion

An Optimized Algorithm for Dynamic Routing and Wavelength Assignment in WDM Networks with Sparse Wavelength Conversion

Dynamic Routing and Spectrum Allocation in Elastic Optical Networks With Mixed Line Rates

Elastic optical networks (EONs) are considered a very promising solution for next-generation optical networks. Elastic spectral bandwidth allocation promotes spectrum utilization efficiency and thus increases the network capacity. One of the fundamental problems in EONs is the routing and spectrum allocation (RSA) problem. Since real EONs may provide only a few regular line rates, we comprehensively study in this paper the dynamic RSA problem in EONs with several mixed line rates. To solve the dynamic RSA problem efficiently, we decompose the problem into RSA subproblems. For the routing subproblem, we propose an efficient multiconstrained routing algorithm named sorted feasible paths searching (SFPS) to find the shortest feasible paths for dynamic traffic demands. The completeness, optimality, and complexity of SFPS are proved. For the spectrum allocation subproblem, we propose two spectrum allocation strategies named fixed segmentation and adaptive segmentation to assign spectrum for the noncommensurate traffic demands of EONs with mixed line rates. Simulation results prove that the proposed dynamic RSA algorithms are time efficient and perform better than existing dynamic RSA algorithms in terms of bandwidth blocking probability and spectrum fragmentation ratio in EONs with mixed line rates.

A decremental approach with the A∗ algorithm for speeding-up the optimization process in dynamic shortest path problems

Dynamic (time-dependent) network routing has become important due to the deployment of advanced traveler information systems in navigation systems. We study the problem of speeding-up the shortest path in continuous-time dynamic networks without a priori knowledge of the link travel times. We apply the A∗ algorithm using the decremental approach to reduce the network size and speed-up the optimization process in dynamic shortest path problems. We utilize the weighted metric multidimensional scaling technique to define the potential function in the A∗ algorithm by converting the link travel costs (times) into distances. Moreover, we evaluate the performance of the decremental approach with respect to the CPU times and optimal costs by applying the A∗ algorithm and Dijkstra’s algorithm to different networks.

Modelling routing in wireless facets dynamic networks using virtual graphs

The general formulation of the problem of routing packets in nonfat faces of network graphs. The common routing process faces in a virtual planar graph. An algorithm for computing virtual path in the virtual plane graphs

Distributed Grooming, Routing, and Wavelength Assignment for Dynamic Optical Networks Using Ant Colony Optimization

The physical resource assignment problem in dynamic optical networks, often referred to as the routing and wavelength assignment problem, is very important for the development of optical transport networks. Research has been done to optimize this operation so that the overall connection blocking can be minimized. Traffic grooming adds another dimension to this problem by introducing opportunities for multiplexing low-bit-rate traffic into a high-bit-rate stream. The ant colony optimization (ACO) algorithm is a metaheuristic method that is inspired by the foraging behavior of ants and has been widely implemented in solving discrete optimization problems. This paper proposes an ACO to solve the grooming, routing, and wavelength assignment problem. Unlike previous work, our work includes considerations of mixed line rate, physical impairments, and traffic grooming functionality. Comprehensive simulation tests show how variations on the ACO algorithms’ implementation affect performance. A comparison is made between this distributed algorithm and a centralized algorithm that we propose, a grooming adaptive shortest path algorithm (GASP). Although GASP shows better efficiency in terms of blocking probability, ACO shows great robustness and adaptivity to varying network and traffic conditions.

Yen-BSR: A New Approach for the Choice of Routes in WDM Networks

AbstractIn this paper we propose to use an iterative algorithm for optimizing the fixed-alternate shortest path routing in the dynamic routing and wavelength assignment (RWA) problem in wavelength routing optical networks. The algorithm performance is compared, in terms of blocking probability, with the Dijkstra and Yen traditional algorithms, as well as with the recently proposed best among the shortest routes (BSR) algorithm. The results suggest that it is feasible to choose an appropriate set of routes for each pair of nodes (source, destination), among the shortest paths and efficiently balance the network load. For all studied scenarios, the proposed heuristic achieved superior performance.

Dynamic Survivable Multipath Routing and Spectrum Allocation in OFDM-Based Flexible Optical Networks

Dynamic Survivable Multipath Routing and Spectrum Allocation in OFDM-Based Flexible Optical Networks

Establishment of Dynamic Lightpaths in Filterless Optical Networks

In this paper, we study the performance of dynamic routing and wavelength assignment (RWA) in filterless optical networks. These types of broadcast and select networks benefit from breakthroughs in advanced transmission technologies for replacing optical filters and active photonic switching devices, such as wavelength selective switches, with passive optical interconnections between nodes, creating passive optical light trees. We introduce an RWA scheme for establishing passive optical lightpaths in a filterless context and managing unfiltered channels at intermediate egress nodes, which, by propagating downstream of the terminating nodes, participate in wavelength usage and increase the risk of wavelength exhaustion. Simulation results are presented for six network topologies, along with the performance evaluation of active photonic and filterless optical network solutions with static and dynamic RWA schemes. We show that the performance of the proposed scheme depends on the average degree of node connectivity.

QoT aware evolutionary programming algorithm for transparent optical networks

This paper presents an evolutionary programming algorithm to solve the quality of transmission (QoT) aware dynamic routing and wavelength assignment (DRWA) problem in transparent optical networks using wavelength division multiplexing (WDM). In this algorithm, the initial population is assumed to consist of a single individual and the algorithm uses only the mutation operator to explore the search space, both the features contributing to a reduction in algorithm execution time. A novel fitness function has been designed that takes into account the number of hops, the path cost, and the variance contributions due to the amplified spontaneous emission (ASE) noise and dynamic crosstalk at the nodes of each lightpath while evaluating a lightpath. This paper also proposes a new wavelength ordering assignment technique to reduce both the switch crosstalk and adjacent channel rejection crosstalk and hence, attempts to improve the mean blocking probability of the incoming call requests. This paper also, analyses the time complexity of the proposed algorithm.

Ant Colony Optimization for Dynamic Routing in Wireless Computer Networks for Improvement in Quality of Services

Routing Assignment (DRA) is a key problem in intelligent optical computer networks. Mathematicians & Computer Scientists started researching the behavior of ants in the early 1990's to find new routing algorithms. The most efficient & widest AI techniques like Swarm particle optimization and Ant colony optimization (ACO) are used to find out solutions for dynamic problems. Ant Colony Optimization (ACO) and in the case of well implemented ACO techniques, optimal performance is comparative to existing top-performing routing algorithms. Such a research has yielded ways to minimize the number of nodes that are taken to get to the destination, techniques for quickly resolving an efficient path, and ways to avoid having loops within a routing scheme. Simulation shows that the modified algorithm decreases the blocking probability and increases the resources utilization comparing with the traditional algorithms.

Dynamic Routing and Resource Assignment Algorithm In sloted optical Networks

All-optical wavelength division multiplexing networks are the most promising candidate for the next generation wideband backbone networks. To improve the utilization of wavelength, time division multiplexing technology is introduced. The routing, wavelength and time-slots assignment problem was studied in such time-space switched networks. Two new dynamic algorithms were proposed which distribute slots of the session request on multiple different wavelengths of single fiber separately based on fixed alternate routing and adaptive routing policy. Especially in LLR-MWLB algorithm, network link weights adjust adaptively with the available time slots of each link and load balancing strategy is adopted. The effectiveness of the proposed algorithms is demonstrated by simulations and results show the better performance. DOI: http://dx.doi.org/10.11591/telkomnika.v11i4.2336

Ultra-high capacity optical networks [Guest Editorial

Increasing the capacity of optical networks has always been an important aim of academic and industrial optical communications research. Bandwidth-hungry applications are challenging the communications network capacity more than ever before, and therefore, research and development aimed at increasing network capacity has become much more urgent over the past few years. Research into ultra-high capacity networks addresses areas such as ultra-high speed transmission, network convergence, dynamic routing, and long-reach optical access networks.

Decentralised covariance control of dynamic routing in traffic networks: a covariance feedback approach

In this study, the authors propose a novel decentralised robust routing control strategy for average and covariance of queue length in a data network. The objective is to control the transitional behaviour of the data networks in response to new traffic load. For each node, the authors design a local state feedback controller based on minimising the worst case of the queue length. The authors then propose an innovative model for covariance of the queue length in each node. To control the average of queue length, local delay-dependent robust controllers are designed based on an equivalent descriptor representation and linear matrix inequalities (LMIs). For covariance control of the queue length, the authors first show that the covariance control problem is equivalent to a standard disturbance rejection problem. Then the authors propose a covariance feedback control law. To investigate the effectiveness of the proposed methodology an example is also presented and extensive simulation results are conducted. Simulation results indicate that the proposed method significantly improves the packet loss and system response time and is able to efficiently control the transient conditions in each.

Dynamic Routing and Wavelength Assignment in Multifiber WDM Networks with Wavelength Conversion Capability

This paper proposes a dynamic routing and wavelength assignment (RWA) scheme in multifiber WDM networks with wavelength conversion capability. In multifiber WDM networks, each link consists of multiple fibers. Thus, multiple lightpaths with the same wavelength can be established in the same link as long as they use different fibers. In WDM networks with wavelength conversion, the network nodes have wavelength conversion capability which can convert one wavelength to another. In order to efficiently utilize multifiber and wavelength conversion capability, an appropriate RWA scheme is necessary. The proposed scheme provides RWA for multifiber WDM networks with sparse and full wavelength conversion capability. In the proposed scheme, a route and wavelengths are selected for each lightpath based on wavelength availability and location of nodes with wavelength conversion capability. Through simulation experiments, we show that the proposed scheme reduces the blocking probability of lightpath establishment efficiently.

OSNR monitoring for QPSK and 16-QAM systems in presence of fiber nonlinearities for digital coherent receivers

OSNR monitoring is indispensable for coherent systems to ensure robust, reliable network operation and potentially enable impairment-aware routing for future dynamic optical networks. In a long-haul transmission link with chromatic dispersion (CD) and fiber nonlinearity, it is difficult to distinguish between amplifier noise and fiber nonlinearity induced distortions from received signal distributions even after various transmission impairment compensation techniques, thus resulting in grossly inaccurate OSNR estimates. Based on the received signal distributions after carrier phase estimation (CPE), we propose to characterize the nonlinearity-induced amplitude noise correlation across neighboring symbols and incorporate such information into error vector magnitude (EVM) calculation to realize fiber nonlinearity-insensitive OSNR monitoring. For a transmission link up to 1600 km and signal launched power up to 2 dBm, experimental results for 112 Gb/s polarization-multiplexed quadrature phase-shift keying (PM-QPSK) demonstrate an OSNR monitoring range of 10-24 dB with a maximum estimation error below 1 dB. For 224 Gb/s PM-16-quadrature amplitude modulation (PM-16-QAM) systems, simulation results demonstrate an OSNR monitoring range of 18-28 dB with a maximum estimation error below 1 dB. Tolerance of the proposed OSNR monitoring technique to different pulse shapes, timing phase offsets, polarization dependent loss (PDL), polarization-mode dispersion (PMD) and WDM effects are also investigated through simulations.

Lightweight Local Area Network Dynamic Routing Protocol for MANET

Lightweight Local Area Network Dynamic Routing Protocol for MANET

Dynamic Routing and Spectrum Assignment in Spectrum-Flexible Transparent Optical Networks

The continual growth of Internet traffic necessitates a high-capacity transmission platform and also highlights the importance of a multi-granularity transport network due to the flexible bitrates of Internet traffic. To meet these challenges, a spectrum-flexible optical network based on orthogonal frequency-division multiplexing (OFDM) transmission technologies has been proposed as a promising solution because of its large transport capacity and bandwidth flexibility. In spectrum-flexible optical networks, we focus on the complete dynamic routing and spectrum assignment (RSA) problem, which integrates the signal format selection subproblem, the routing subproblem, and the spectrum assignment subproblem. In the complete RSA problem, we jointly consider the spectrum continuity constraints, the transmission distance constraints, and the relationship between the traffic bitrate and the signal bandwidth. A nonlinear programing model is presented to state the complete RSA problem. To solve the problem, we introduce a decomposition approach that divides the nonlinear problem into three steps: selecting the modulation format, solving the linear basic RSA problem, and checking the transmission distances. Based on the decomposition, we propose two heuristic approaches: modulation level fixed and adaptive RSA approaches for the complete RSA problem. Through analysis of the approaches, we prove that, in theory, the modulation level adaptive RSA approach can find the optimal solution to the complete RSA problem. The two approaches are implemented and compared in simulations. The results prove that the modulation level adaptive approaches achieve a lower capacity blocking probability than the modulation level fixed approaches.