Krzysztof Stachowiak

Lagrangian relaxation in the multicriterial routing

Communications networks routing is not a new subject. However, with a growth of packet networks and the increase of their range and importance, the task of conveying information over the web has grown beyond its original shape and has become far more sophisticated. It is no longer computer scientists and the military that make use of the global network exclusively; it can be stated that almost every possible group from the global population has numerous representatives among Internet users. This fact is coupled with a decrease in the popularity of the original communication media such as the telephone and the e-mail. This is mainly due to them being assimilated into packet networks along with the process of network convergence. A number of different types of information streams in packet networks has been observed and classified. It turns out that careful resources management itself may lead to an increase in the information transporting efficiency. In this paper, an approach is explored - the Lagrangian relaxation - that enables incorporating multiple criteria into the routing problem solution. At the same time, the low computation complexity is maintained that enables further consideration of the technique also in practical scenarios.

Quality of multicast trees in ad-hoc networks with topology control

The article analyzes and explores the performance of multicast heuristic algorithms and quality of multicast trees in ad-hoc networks. It also provides a detailed analysis and a description of the implementation of methods for the topology generation in ad-hoc networks with the application of topology control protocols. Network topology planning and performance analysis are crucial challenges for wire and wireless network designers. They are also involved in the research on routing algorithms and protocols for ad-hoc networks. In addition, it is worth to emphasize that the generation of realistic network topologies makes it possible to construct and study routing algorithms, protocols and traffic characteristics for ad-hoc networks.

Multi Criterion Multicast Routing Algorithm Comparison for Large Networks

Abstract QoS enabled multicast routing is known to be of non-polynominal complexity, which leads to the necessity of using heuristic algorithms to find sub-optimal solutions to the problems of this class. The evaluation of such algorithms requires the use of the simulation techniques as the heuristics’ results are of stochastic nature. Because of the problem complexity the simulation times increase significantly in the function of the network size, therefore the results presented in the literature are often limited to only small models. In this article the results of the evaluation of different multicast QoS routing algorithms (further referred to as the Multi-Constrained Minimum Steiner Tree Problem - MCMST) have been presented for a wide range of network sizes reaching thousands of nodes.

Comparison of Different Path Composition Approaches to Multicast Optimization

In this paper the different algorithms that are based on the different interpretations of the path composition have been evaluated and compared. A new technique – the Aggregated MLARAC has been proposed and described. Two different ways of the algorithm performance evaluation have been utilized in order to present the different aspects of the considered algorithms.