Andriy Luntovskyy

Limit cycles in PI control loops with absolute deadband sampling

Absolute deadband sampling is used in discrete control systems for reduction of the number of produced events. Under proper conditions, this sampling type results in limit cycles in steady state, which lead to increased number of events and deteriorate the sampling efficiency. This paper investigates the condition of emergence of limit cycles in the closed control loops with PI controllers, as well as the frequency of limit cycles.

Cross-layered wireless network planning and modeling methods and tools

Prominent tools for design of WLAN and WiMAX networks are examined and compared. Despite of the evident advantages of current tools there is a wide field for future improvements. Simulation tasks for wireless networks with increased accuracy and adequacy require execution of multiple computing steps. Algorithms like the Dominant Path Prediction Model with fine raster step and exponential complexity has to be compulsory parallelized. The peculiarities of accurate cross-layered simulation within CANDY tools are examined. Parallelization programming techniques are represented.

Propagation modeling and placement algorithms for wireless sensor networks

The energy efficiency is critical for application of wireless sensor networks, since it is a main precondition for their long-live functionality, small modification costs and reliability. This paper deals with the placement of wireless nodes based on the modeling of radio wave propagation. The methods are realized in a planning tool CANDY Wireless Site Finder that provides optimized topologies of wireless networks under considering of transmitted power, frequencies, propagation environments (in-door/out-door) and obstacles given in CAD-compatible formats. The tool is integrated in the framework of other CANDY tools aimed to efficient planning of heterogeneous wired and wireless networks.

Integrated design of office communication and building automation networks

Building automation communication systems become today more and more integrated in office communication networks using Ethernet. The paper considers integrated design of both networks, which will allow to use the cable and server infrastructure more effectively. Types of information that should be exchanged between design tools are considered. An approach to contributive using and exchange of design information with the help of XML and XSL transformations is proposed and illustrated by a case study.

Integrated design tools for combined LAN

Nowadays high-performance combined wired and wireless LANs are of great importance for companies and organizations of any size. However, efficient remains a challenge, since existing design tools only provide limited and hardly integrated support. The CANDY project was launched in 2003 with the aim to improve this situation by proposing an integrated design methodology with extensive tool support for all network design sub-tasks. This paper illustrates the CANDY network design methodology by giving an overview of the integrated design approach and presenting two advanced algorithms for design of wireless local area networks.

Models and Methods for WLAN / WIMAX-Network Design

Parallel with the traditional cabled solutions for the enterprise communication networks (CN) based on Ethernet/ATM LANs the WLAN/WiMAX networks (world wide interoperability for microwave access) became more significant as the wireless routes. Therefore wireless network design is closely tied to the traditional design problems for infrastructure CN. Certain models and design methods are examined in this paper

Design particularities for wireless networks

Particularities of design for innovative wireless networks-WLAN and WiMAX-are examined. Models and methods for wireless networks design are investigated. Main requirements as well as integration way into a XML-based network design environment is shown

Architectural Transformations in Network Services and Distributed Systems

With the given work we decided to help not only the readers but ourselves, as the professionals who actively involved in the networking branch, with understanding the trends that have developed in recent two decades in distributed systems and networks. Important architecture transformations of distributed systems have been examined. The examples of new architectural solutions are discussed.

Network Design and Optimization Under Use of Candy Framework

CANDY, computer-aided network design utility is a Java-framework for an efficient XML-based integrated network design environment developed via CANDY@TUD initiative. This paper examines CANDY network design tools including graphical input and topology verification, cabling system tracing and APIBS constellation (AP-access point, BS-basis station), performance analysis with feed-backs to reengineering procedures. In the investigation focus stand cabling system geometry and costs optimization. The integrating component for these design tools is NDML (network design markup language), XML-based problem-oriented language developed for representation of design data and workflow consisting of the following special parts: NDML basics, topology, performance, radioNDML for radio-networks etc

Dynamic evaluation of costs in combined wired and wireless LAN

Evaluation and prediction of the overall costs for installation and upgrade of combined wired and wireless LAN under consideration of the time factor are presented in this paper. Advanced dynamic costs models under considering of different QoS requirements are investigated. These models allow more exact prediction of network costs at some time moment in the future. The determining of cost model parameters is discussed. The network costs optimization approaches are used to define the necessary capital expenditures in the time moment of network upgrade.