a software tool for rnp optimazation

8/6/2019 A Software Tool for RNP Optimazation

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A SOFTWARE TOOL FOR RADIO COMMUNICATION

NETWORK OPTIMIZATION

Marek Horvth1, Jozef Petrek

KRE FEI STU, Ilkoviova 3, 812 19 [email protected], [email protected]

Abstract: This paper presents a new software tool for radiocommunication network topologyoptimisation. The tool uses the digital network database of the Slovak republic and is a base

for the network topology optimisation algorithms application.

1. Introduction

The task of an economical service of communication networks is a crucial issue in present-day competing environment. The authors dispose of some powerful network topologyoptimisation algorithms [1], which work very well assuming that the cost functions of allnetwork links are known, this means that the length-cost function for all links is exactlyknown.Unfortunately this is not the case for not-rented microwave radio links. The cost of a link

depends not on the link length, frequency band and bandwidth exclusively but also on theterrain profile, power line availability, node locality rent cost and other variable factors. Thegoal of our effort was to create a software environment for the radio network optimisationwhich could be skilful for network providers.

2.Radio link cost function

In our consideration we used following link cost function cl or node cost function cnrespectively:

l

l

l

l oe

ic += n

n

n

nn oe

irc ++= (1)

where index lis for a link and indexn for a node,ris the rent cost [$/month]

2

iis installation cost [$]eis the life expectancy of the considered network component [month]ois the operation cost [$/month]rnis the rent cost for a place where the provider may place its technology. When the providerowns the parcel or building yet,rn= 0.onis the cost of maintenance of the node, assumed electricity consumption etc.in is the cost for building modifications for rented space or erection of provider ownedbuilding respectively, cost of antenna mast, cost of power line installation, cost of all node

technology except of those which is included in the link installation cost il .We isolated the cost, which are typical for a node from the cost of link not to duplicate thesame cost because one rented site, building, antenna mast may guest more links.The most complicated entry is the cost of power line installation because it crucially dependson the low voltage accessibility. In the process of new network planning the optimisedlocations of all network nodes are not known. To be able to optimise the network also in this

1 Marek Horvth has written his graduation thesis at KRE FEI STU under supervision of Jozef Petrek2 $ is the symbol for the local currency

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phase we plan entering positions of distinguished power supply nodes and introduce thepower lines with simplified cost function similar to the communication line cost function. Inour tool for the simplicityrn+on is only one parameter (Cost of operation, see Fig.1).When the link keeps the network operator (the link is not rented from another operator), the ilis cost for all needed technology (transceivers, receivers, antennas and cables etc.) on bothends of the link.

Fig.1 Network nodes and links editing tool

3. Basic features of the tool

For the easy editing of network nodes and links an editing tool was made (see Fig. 1.)To realise a microwave link between two points A and B sometimes a relay station isnecessary because of the rugged topography or long distance betweenA andB.The maximal length of one hop microwave linkdmax we calculate from equation (2)

20

log20

10max

fAkpPGTP

d

++

=

[ ]GHzdBdBdBmdBidBmkm ,,,,,, (2)

Where PT is the transmitter power

G is the sum of transmitter and receiver antennas gainsPP is the receiver sensitivityk is the sum of cable and connector attenuation in both transceiver and receiver sides

4,92604

1log10loglog20 9

+=

c dB is a constant coming from the radar

equation and unit transcending;c is the light velocity in m/s

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A is a gain reserve, which is necessary because of additional atmospheric waveabsorption, which depends on frequency band and local weather condition. In 23 GHzband we useA=20 dBfis the used frequency

Fig.2. Plane map of the terrain with Fig.3. 3D view of the terrain profilea designed network

The exact locality of a node side can be edited entering the exact geographical coordinates ofa node. Unfortunately there are more geographical coordinate systems. This tool worksdefault in the Slovak S-JTSK system but supports also the transcoding from the military S-42WGS-84 respectively. So the coordinates measured using the GPS satellite system can easilybe used.After editing the node (and link if any) coordinates in the editing tool (Fig. 1) the user can seethe plain map with network nodes (and links). The scaling factor is set automatically (Fig.2)according to network dimension. A 3D model of the terrain profile is also available (Fig. 3).

Clicking on a link, choosing two network nodes or writing geographical co-ordinates of twopoints a terrain profile between two points can be displayed (Fig.4). The antenna altitudes aretaken from the network station file. The first Fresnel zone is also depicted. The radius of then-th Fresnel zone is calculated using (3) [3]

21

21

dd

ddnrn

+

= (3)

where is wave length, d1 and d2 are distances of the transmitter and receiver antennasrespectively.

A skilful radio network design tool is the visibility tool (Fig.5) which finds quickly a visibilityto nodes from a chosen network node or visibility to terrain from a chosen terrain point to alldirections.The used digital terrain database has 100 meter grid therefore between two database points inthe real terrain some local extremes may occur. To predict the extremes a interpolationmethod can be used. Three possibilities can be chosen:

without interpolation, linear interpolation two-dimensional sampling theorem [3].

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For longer links also the earth curvature should be taken into account. The tool provides threepossibilities, one of them has to be chosen by the user:

without earth curving radio earth curving ( er RR

3

4= = 8493 km, whereRe is the earth radius,Rr is an equivalent

earth radius

optical earth curving

Fig.4. Terrain profile Fig.5 Visibility tool

4. Conclusion

This tool is a base for radio network topology optimisation. Similar to all other comparabletools is not able to grand safe results because of insufficient detail or inaccuracy of digital

terrain database. In the cities the building are not included in the database, in rural areasusually forest vegetation might change the real visibility result. Therefore the visibility ofantennas should be proven on-site before starting final project of installing all radioequipment.After finishing the continuing work on network topology optimisation could the tool can savemuch resources for network operators.

5. References

[1] Petrek J.: Hierarchical communication network topology optimisation. KRE FEI STUBratislava 1998, PhD. theses, p. 107[2] Ericson: Ericson Mini-Link System Planning, Sweden, Mondal: Ericson Microwave

System AB, 2002[3] Klima J., Klime J.: Vpoet intenzity elektromagnetickho poa v psmach VKV a UKV,Nadas Praha, 1988, p.144[4] Horvth M.: Radiocommunication network topology optimisation. KRE FEI STUBratislava 2003, Graduation theses, p. 81[5] Federln ministerstvo spoj: Metodika vpotu a plnovn rdiorelovch spoj, Praha1984, MDT 621.396.43.001.1:001.8

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a software tool for rnp optimazation

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