Optimization Of Communication Networks Research Articles

EVCS — A COMPLETE ELECTRONIC VIRTUAL CONFERENCE SYSTEM

Electronic activities are realized on the Internet due to the growth of the Internet. As conference organization is getting more popular, we proposed an electronic virtual conference system (EVCS) to handle all activities of real-world conferences. The EVCS includes a virtual conference management system (VCMS) and a mobile conferencing system (MCS). Video conferencing is a trend of future communications. With the improvement of broadband network technologies, video conferencing becomes possible in the global society. It is feasible to use video conferencing technologies to organize future international conferences. As such, transportation and accommodation costs are saved. This paper proposed a total solution toward virtual conferencing. We use a mobile server/storage pre-broadcasting technique, as well as a communication network optimization algorithm, which is based on a graph computation mechanism. The system also relies on a network bandwidth reservation facility as well as a multicasting control function. With the assistance of the virtual conference management system, the system is able to support virtual conferencing in the future academic society.

A neural approach to topological optimization of communication networks, with reliability constraints

Consider network topological optimization under a reliability constraint. The objective is to find the topological layout of links, at minimal cost, under the constraint: all-terminal network reliability is not less than a given level of system reliability. The all-terminal reliability is Pr{every pair of nodes in the network can communicate with each other}. This paper presents a new approach based on artificial neural networks (ANN) for solving the problem. The problem is mapped onto an optimization ANN (OPTI-net) by constructing an energy function whose minimization process drives the neural network into one of its stable states. This stable state corresponds to a solution for the network design problem. The OPTI-net favors states that correspond to a selection of links with an overall reliability greater than or equal to a threshold value. Among these states it also favors the one which has the lowest total cost. Hysteresis McCulloch-Pitts neuron model is used in the solution, due to its performance and fast convergence. Considering the NP-hard complexity of the exact reliability calculation, together with the iterative behavior of the neural networks, bounds for the all-terminal reliability are used. This paper introduces new upper and lower bounds that are functions of the link selection and uses them to represent the network reliability. The neural network is tested via computer simulation using three problem sets. The first two sets are used to compare the results obtained by this method to those obtained by previous heuristics. The third test set contains five networks of larger sizes for which no results have been reported by previous methods. This paper rinds the optimal or near-optimal solutions for most of the problems in a relatively short time. The OPTI-net found many good solutions for a 50-vertex 1225-arc network in 1/2 CPU hour. For each problem instance, many solutions are found at each run of the simulator. The strengths of this neural network approach are very slowly increasing computation time with respect to network size, effective optimization, and flexibility. The OPTI-net is very effective in identifying optimal, or suboptimal, solutions even in search spaces up to /spl ap/10/sup 16/ for a fully connected network with 50 vertexes. The OPTI-net is the first approach to be applied on such large networks. The simulation results show that the neural approach is more efficient in designing networks of large sizes compared to other heuristic techniques.

Poisson-Voronoi Spanning Trees with Applications to the Optimization of Communication Networks

We define a family of random trees in the plane. Their nodes of level k, k= 0, …, mare the points of a homogeneous Poisson point process Πk, whereas their arcs connect nodes of level kand k+ 1, according to the least distance principle: If Vdenotes the Voronoi cell w.r.t. Πk+1with nucleus x, where xis a point of Πk+1, then there is an arc connecting xto all the points of Πkthat belong to V. This creates a family of stationary random trees rooted in the points of Πm. These random trees are useful to model the spatial organization of several types of hierarchical communication networks. In relation to these communication networks, it is natural to associate various cost functions with such random trees. Using point process techniques, like the exchange formula between two Palm measures, and integral geometry techniques, we show how to compute these average costs as functions of the intensity parameters of the Poisson processes. The formulas derived for the average value of these cost functions can then be exploited for parametric optimization purposes. Several applications to classical and mobile cellular communication networks are presented.

Heuristic algorithms for reliable multiplexed network design

AbstractA heuristic optimization algorithm is presented for topological optimization of wideband communication networks whose structure is based on a single central office and on a number of multiplexing centres. The reliability problem is discussed in detail introducing in the objective function a cost term related to the probability of failures. Optimization is performed in two steps. In the first step a tree non redundant network is determined, providing the starting configuration for the second step, in which redundant edges are introduced. Cross‐connect devices replace multiplexers when suitable, and a very general mesh topology is created. Statistics on a large number of test networks are reported. Network costs and reliability performances are deeply investigated.

Reliability optimization of communication networks using simulated annealing

Two concepts of communication network reliability are considered. The first one, the ‘s-t’ reliability, is relevant for communication between a source station and a terminal station as in the case of a two way telephone communication. The second one, the overall reliability, is a measure of simultaneous connectedness among all stations in the network. An algorthm is presented which selects the optimal set of links that maximizes the overall reliability of the network subject to a cost restriction, given the allowable node-link incidences, the link costs and the link reliabilities. The algorithm employs a variaton of the simulated annealing approach coupled with a hierarchical strategy to achieve the gobal optimum. For complex networks, the present algorithm is advantageous over the traditional heuristic procedures. The solutions of two representative example network optimization problems are presented to illustrate the present algorithm. The potential utilization of parallel computing strategies in the present algorithm is also identified.

Communication network optimization

The major facets of the branch of combinatorial optimization, known as communication network optimization, are surveyed. The basic principles are briefly investigated, followed by a discussion of location, connection and traffic routing problems. In each case the relevant existing algorithms are listed, together with some suggestions concerning the likely areas of investigation in future years.

Perturbation analytic methodologies for design and optimization of communication networks

Perturbation analysis (PA) is a technique for estimating performance sensitivities of queuing networks from direct observation of a single stochastic realization. It is used here to address such problems for communication networks. For a G/G/1 link model, it is shown that efficient PA algorithms can be used to estimate online the marginal delay of messages due to incoming flow perturbations. This information is used in a minimum-delay distribution algorithm to optimize routing. PA algorithms are extended to estimate throughput and mean delay sensitivities with respect to link capacities, including blocking phenomena due to finite queues. A window-flow-control model is considered, and experimental results of PA estimates for throughput sensitivities are provided. these estimates are seen to be accurate under heavy-load conditions, but, in general, enhanced PA techniques are required to incorporate more-complicated dynamic flow control and routing policies.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Routing optimization in packet switching communication networks

For routing assignments a special model and an optimization algorithm are proposed. The efficiency of the routing assignments is evaluated by the average value of the total cost of delays for all packets in the network. It is the objective function. The main idea is that traffic, which is transmitted from the source node to the destination node, can be split between two or more logical paths. The minimum of the objective function can be found by varying the traffic on every path and simultaneously from all the source nodes to the destination nodes. If this approach is applied, then the objective function is nonseparable and nonlinear. Because its shape is unknown in advance, an adaptive nonlinear optimization algorithm is proposed. For evaluating its efficiency a special set of test functions has been used.

Optimization of mixed-media communication networks

In the design of a communication network one may consider, among others, response time, cost, throughout, reliability, availability as performance parameters. Satellite communication technology introduces new opportunities to satisfy these considerations by taking advantage of characteristics inherent in satellite links as well as that in terrestrial links (e.g., satellite links have greater inherent delays but may have more cost effective channel bandwidth than terrestrial links.) In this paper, we describe an algorithm for the problem of designing a store-and-forward packet-switched computer communication network with multiple packet classes using both terrestrial and satellite links. The algorithm is heuristic in nature and is an extension of the design algorithm which has been developed for designing terrestrial networks to include satellite links. As for satellite access methods, only dedicated channel access methods are considered. Some design examples are also given.