MODELS AND METHODS FOR WLAN / WIMAX- NETWORK DESIGN

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Andriy Luntovskyy, Dietbert GCitter, Alexander Schill Dresden University of Technology, Department of Computer Science, Hans-Grundig-Straβe 25, 01062 Dresden, Germany guetter@rn.inf.tu-dresden.de http://www.inf tu-dresden.de

Abstract – Parallel with the traditional cabled solutions for the enterprise communication networks (CN) based on Ethernet/ ATM LANs the WLAN /WiMAX networks (Worid- 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 below [3].

I.                  Wireless routes deployment

The typical deployment scenario is as it follows: those wireless routes partially substitute the building cabling sub-system and at mid-term can also be used instead ofthe campus subsystem or as an efficient backbone solution (Fig. 1). The constellation of АР/ BS for wireless networks is a complex multi-criteria/parameter optimization problem. The generalized formula for this mini-max-oDtimization process is aiven below [1-61:

Among the important requirements to the used design models and algorithms for wireless networks act the following features: accuracy, complexity, relevance for defined frequency bands and propagation effects (e. g.

Fig.1. Up-to-date and mid-term wireless deployment integrated scenario

where К – overall cost function for enterprise CN, Nuser – number of corresponding users. Nap – number of AP, Nbs – number of BS, N – number of used network devices, L – common cabling system length, DR – data rate, d (x, y) – distance Tx-Rx for AP/BS, DRmin ,, i=1, Nuser – DR constraints, Hbs – accepted antenna mast height for BS, Srf (S, d) – RF illumination surface as a function of signal power S (x, y), r- minimal radius for 1^^ Fresnel zone, h (x, y) – height of geometrical/geographical point (x, y), {(X, Ygps) upper, (X, Ygps) lower} – absolute GPS – coordinates.

reflection and multi-path propagation) as well as the requirements to LOS, indoor/outdoor, used frequencies and maximal range Tx-Rx, certain environmental limitations (used materials, types of walls, roofs, streets, hills etc.) [7-16]. Generally RF signal strength is weakened [9] via the following EM-wave propagation effects (fig.2):

Fig. 2. Modeled propagation effects for wireless communication

II.    Visualization and positioning methods for wireless design

The classification of existing models and in CANDY used visualization-positioning algorithms is given in Fig.

3.     Empirical and semi-empirical models are not satisfying accurate; sometimes they do not work well with higher frequencies or locality/ environment types. The ray-optical models combine acceptable complexity degree (O (n^)) and accuracy; they are relevant practically for each frequency bands or environmental types [11, 3].

Fig. 3. Visualization and positioning algorithms for WLANAA/iMAX

Some important methods are relevant for WLAN/ WiMAX indoor/outdoor and CANDY framework implementation are discussed below (Table 1):

III.                              Design examples

Due to consequent optimization routines deployment a suboptimal by Bellman constellation (Tx, Rx) for WLAN802.11 AP/WiMAX 802.16 BS can be obtained. Design example for WLAN 802.11. In the most cases for design of WLAN 802.11 a cellular structure is recommended. Let us consider indoor WLAN combined with Ethernet 802.3, for a example, a university building (with lecture halls, laboratories, computing center). The mini-max problem has to be solved:

An optimized AP constellation obtained via CANDY Site Finder is given in Fig.5.

Design example for WiMAX 802.16. For instance, an enterprise campus is illuminated via WiMAX BS 802.16a antenna (in mid-term: F=3.5 – 5.8GHz in Russia and Ukraine, Germany and other European countries). The LOS-contact for Tx-Rx is necessary. The penetration conditions for 1st Fresnel zone are proved by specified distance, heights for Tx-Rx antennas and given downtilt angles ang (x, y).

where d – distance, r – minimal radius of 1®^ Fresnel zone. In Fig.6 the deployment of CANDY Site Finder [^- 5], a tool for optimal constellation of WiMAX 802.16 BS, is represented. Digital height maps, building plans, input data and computation results can be described in the following well-known and proprietary formats: JPG, PDF, Python CAD XML, NDML, RadioNMDL, ifcXML.

Fig. 4. CANDY: 802.11 WLAN AP constellation, DR and RF distribution via MClSA

Fig. 5. CANDY: 802.16 WiMAX BS constellation and RF coverage via COST Wl

IV.                                  Conclusions

Wireless routes are widely used in the frame of integrated enterprise networks design and parallel to the wired infrastructure built via IEEE 802.3 and SCS EN50173. The wireless networks design methods and models are examined in this work. The described CANDY Site Finder tool implements certain efficient semi-empirical and ray-optical methods and can be deployed for optimization of AP/BS constellation of IEEE 802.11 AP and IEEE 802.16 BS. The digital height maps, building plans, input parameters and visualization of computation results can be described via several wide-spread graphical formats as well as via the NDML/ RadioNMDL format implemented especially for CANDY Framework.

V.                                     References

1.      CANDY@TUD Learning Project: http://www.rn.inf.tu- dresden.de

2.      Luntovskyy, A., Gutter, D., Schill, A., Winkler, U.: Concept of an Integrated Environment for Network Design; IEEE CriMiCo Conference, Sevastopol, Sept. 2005, pp. 959-961 (ISBN966-7968-79-0).

3.      Luntovskyy, A., Gutter, D., Schill, A., Winkler, U.: Design Particularities for Wireless Networks; IEEE CriMiCo Conference, Sevastopol, Sept. 2005, pp. 955-958 (ISBN966- 7968-79-0).

4.      Luntovskyy, A. Schill, D. Gutter, G. Pfeifer, A. Panchenko, CANDY: Integrated Environment for Network Design. Proceedings of SCI 2004, Orlando, pp. 252-257, ISBN 980-6560-13-2.

5.      Luntovskyy, A., Schill, A., D. Gutter, G. Pfeifer,

A. Panchenko, V. Vasyutynskyy: Computer Network Modeling and Analysis Using XML-Descriptions; The 9th World Multi-Conference on SYSTEMICS, CYBERNETICS AND INFORMATICS (WMSCI 2005), July 10-13, 2005, Orlando, Florida, USA, pp. 283-288, ISBN 980-6560-54-3.

6.      W. Lehnert: Planung & Optimierung v. Telekomm.-Netzen; ManuskriptTUD,WS 04/05.

7.      N. Geng: Planungsmethoden fCir die Mobilkommunikation; ISBN 3-540-64778-3.

8.      H. Sizun: Radio Wave Propagation for Telecommunication Applications; ISBN 3-540-40758-8.

9.      Ron Olexa. IMPLEMENTING 802.11, 802.16,

802.20 WIRELESS NETWORKS (ISBN: 0-7506-7808-9, 09/2004).

10.    Clint Smith, John Meyer: 30-WIRELESS WITH 802.16 AND 802.11/ WIMAX AND WIFI (ISBN: 0-07- 144082-8, 10/2004)

11.    Ralf Wolfe: http://www.ralf-woelfle.de/elektrosmog/index.htm

12.    Uni Karlsruhe: http://www.ihe.uni-karlsruhe. de/forschung/wap/welle.de.html?frame=yes

13.    EMF-Forschungsprogramm: http://www.emf- forschungsprogramm.de/forschung/dosimetrie/dosimetrie_ abges/dosi_015_AB. pdf

14.    Foyer, de: http://www.foyer.de/fms/projekte/p_ii/p_ii_1/indoor.htm

15.    AWE Comm.: http://www. awe-communications.com/

16.    Helena Unger, Djamshid Tavangarian, Steffen Silberbach. Simulationsbasierte Planung von Wireless LAN HotSpots/ InstitutfCirTechnische Informatik, Fachbereich Informatik, Universitat Rostock, 2003.

Glossary

AP – Access Point BS – Base Station

CANDY – Computer-Aided Network Design utility, Java- framework for an efficient XML-based integrated network design environment developed via CANDY@TUD initiative.

CANDY Site Finder – Java/XML-based design tool for WLAN/WiMAX networks

CN – enterprise communication/computer networks DR – data rate

GPS – Global Positioning System, international satellite-based navigation system LOS – Line-of-Sight

NDML – Network Design Markup Language), XML-based problem-oriented language developed for representation of design data and workflow QoS – Quality of Service RF – radio frequency Rx – receiver

SCS – Structured cabling system Tx-transmitter

WiMAX – Worldwide Interoperability for Microwave Access

Источник: Материалы Международной Крымской конференции «СВЧ-техника и телекоммуникационные технологии», 2006г. 

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