Journal of Engineering Path Loss Model Using Geographic ... · of the link budget of a telecommunication system. It is the ... and the calculated pathloss displayed. This was overlayed

International Journal of Engineering and Technology Volume 3 No. 3, March, 2013

ISSN: 2049-3444 © 2013 – IJET Publications UK. All rights reserved. 269

Path Loss Model Using Geographic Information System (GIS)

Biebuma, J.J, Omijeh. B.O Department of Electrical/Electronic Engineering,

University of Port Harcourt

ABSTRACT

This paper presents Geographic Information System (GIS) as an invaluable tool in path loss modeling. It shows how GIS can

reveal features through its visualization capabilities. A program was written in Visual Basic for Applications (VBA) to

automatically compute the path loss using Cost 231 Hata Model, and display it spatially on an administrative map and

satellite imagery (Land Use/Land Cover) using ArcMap 9.0 Application. The results gotten were tested to be consistent with

results of previous study done in Southern Nigeria and it shows how the excellent visualization and spatial handling

capabilities of GIS gives it an extra advantage as a path loss modeling tool. Thus, the integration of GIS into existing path

loss analysis applications is recommended for fast, accurate and exciting results brought about by the ability to visualize the

terrain and other great features.

Keywords: Geographic Information Systems, Path Loss, Cost 231 Hata, Model

1. INTRODUCTION

A Geographic Information System is a system of

hardware, software and procedures to facilitate the

management, manipulation, analysis, modeling,

representation and display of geo-referenced data to solve

complex problems regarding planning and management of

resource. But GIS is much more than maps. A GIS can

perform complicated analytical functions and then present

the results visually as maps, tables or graphs, allowing

decision-makers to virtually see the issues before them

and then select the best course of action. There are several

spatial applications in use such as ArcGIS, MapInfo etc.

The most prominent of which is the ArcGIS developed by

ESRI (Environmental System Research Institute),

Redlands.

ArcGIS is a suite of software product lines produced by

ESRI. At the desktop GIS level, ArcGIS can include:

ArcReader, which allows one to view and query maps

created with the other Arc products; ArcView, which

allows one to view spatial data, create maps, and perform

basic spatial analysis; ArcEditor which includes all the

functionality of ArcView, includes more advanced tools

for manipulation of shapefiles and geodatabases; or

ArcInfo the most advanced version of ArcGIS, which

includes added capabilities for data manipulation, editing,

and analysis.

Path loss is a major component in the analysis and design

of the link budget of a telecommunication system. It is the

attenuation undergone by an electromagnetic wave in

transit between a transmitter and a receiver in a

communication system. Path loss may be due to many

effects, such as free-space loss, refraction, diffraction,

reflection, aperture-medium coupling loss, and

absorption. Path loss is also influenced by terrain

contours, environment (urban or rural, vegetation and

foliage), propagation medium (dry or moist air), the

distance between the transmitter and the receiver, and the

height and location of antennas. There are several path

loss models, prominent of which are reviewed below.

2. LITERATURE REVIEWS

The Okumura et al. method is based on empirical data

collected in detailed propagation tests over various

situations of an irregular terrain and environmental

clutter[1]. The results are analyzed statistically and

compiled into diagrams. The basic prediction of the

median field strength is obtained for the quasi-smooth

terrain in an urban area[2]. A correction factor for either

an open area or a suburban area is also taken into account.

Additional correction factors, such as for a rolling hilly

terrain, an isolated mountain, mixed land-sea paths, street

direction, general slope of the terrain etc., make the final

prediction closer to the actual field strength values [3] .

The Okumura model is formally expressed as:

L = LFSL + AMU – HMG - HBG (1)

where,

L = Median path loss (dB).

LFSL = Free Space Loss (dB).

AM = Median attenuation (dB).

HMG = Mobile station antenna height gain factor.

http://en.wikipedia.org/wiki/Transmission_medium

http://en.wikipedia.org/wiki/Coupling_loss

http://en.wikipedia.org/wiki/Absorption_%28optics%29

International Journal of Engineering and Technology (IJET) – Volume 3 No. 3, March, 2013


HBG = Base station antenna height gain factor.

2.1 Lee Model

Lee.W.C.Y proposed this model in 1982 [4]. In a very

short time it became widely popular among researchers

and system engineers mainly because the parameters of

the model can be easily adjusted to the local environment

by additional field calibration measurements (drive tests).

By doing so, greater accuracy of the model can be

achieved. In addition, the prediction algorithm is simple

and fast.

2.2 COST-231 Hata Model

The Hata Model [5] is an empirical formulation of the

graphical path loss information provided by Okumura.

Hata presented the urban area propagation loss as the

standard formula and supplied correction equations to the

standard formula for application to other situations [6].

PL = 46.3 + 33.9 log10 (f) – 13.82log10 (hb) - ahm + (44.9 – 6.55log10 (hb)) log10 d + cm (2)

Where, f is the frequency in MHZ, d is the distance

between the transmitting and the receiving antennas in

km; hb is the transmitting antenna height above ground

level in meters. The parameter cm is defined as 0 dB for

suburban or open environments and 3 dB for urban

environments. The parameter ahm is define for urban

environments,

ahm = 3.20 (log10 (11.75hr)) 2 – 4.97, for f > 400MHz (3)

for suburban or rural (flat) environments,

ahm = (1.1log10f – 0.7) hr – (1.56log10f – 0.8), (4)

where, hr is the receiver antenna height above the ground

level.

Equally make a provision for rain attenuation that is the

total path loss to be added to the rain attenuation.

3. DESIGN METHODOLOGY

In this design, the Cost 231-Hata Model was used[7].

Using Microsoft Access, a database to capture the

parameters in the COST-231 Hata model and the

geographic Coordinates of the transmitter and receiver

stations was set up. A form to link to the database was

created. The path loss was calculated using VBA code

which was linked to a button in the form. The table was

imported into ArcCatalog as a geodatabase and displayed

as an ESRI shapefile on ArcMap. The points were joined

and the calculated pathloss displayed. This was overlayed

with administrative boundaries and satellite imagery (land

use/ land cover). Results gotten were tested to be

consistent with a previous research carried out [8][9][10].

3.1 Mathematical Model

In carrying out Path loss analysis, COST-231 Hata Model

equation was used to model the path loss using industry

data from the region.

PL=46.3 + 33.9log10 (f) – 13.82log10 (hb) - ahm +(44.9 – 6.55log10 (hb))log10d + Cm (5)

Where, f is the frequency in MHZ, d is the distance

between the transmitting and the receiving antennas in

km; hb is the transmitting antenna height above ground

level in meters. The parameter Cm is defined as 0 dB for

suburban or open environments and 3 dB for urban

environments. The parameter ahm is define for urban

environments,

ahm = 3.20 (log10 (11.75hr)) 2 – 4.97, for f > 400MHz (6)

for suburban or rural (flat) environments,

ahm = (1.1log10f – 0.7) hr – (1.56log10f – 0.8) (7)

where, hr is the receiver antenna height above the ground

level.

3.2 Algorithm

i. Declare all variables using the appropriate

format/structure (PL, f, hr, hb, ahm, Cm and

coordinates both for receiving and transmitting

stations

ii. Create a table in a database with the declared

variables as the fields

iii. Create a form containing identical fields with the

table created

iv. Link the table with the form

v. Input Cordinates and Station information

vi. Set values for the terrain (Urban, Suburban and

Rural)

vii. Define the parameter ahm for different terrain

conditions, that is:

Urban - ahm = 3.20 (log10 (11.75hr)) 2 – 4.97

Surburban/Rural - ahm = (1.1log10f – 0.7) hr –

(1.56log10f – 0.8)

viii. Define value of Cm for the different terrain

conditions:



Urban, Cm = 3, Suburban/Rural, Cm = 0

ix. Input other Parameters (f, hr, hb and d)

x. Compute Pathloss the Cost 231-Hata model

showed below:

PL = 46.3 + 33.9 log10 (f) – 13.82log10 (hb) - ahm

+ (44.9 – 6.55log10 (hb)) log10 d + cm

xi. Output Computed value of Pathloss

Figure 1 shows the Flowchart for Path loss Analysis using

Cost 231-Hata Model

Fig 1. Flowchart for Path loss Analysis using Cost 231-Hata Model



Fig 2 Path loss calculation application interface

Table 1 Pathloss results for Different stations

Link Name,

MO

DE

Tx

Power

Antenn

a Antenna

Cable

type

Path

loss

Fade

Rx

Level

Latitude, Gain Height

With

Losses Margin

Longitude Distance

Odeama creek

/Soku

04 33 39 N LOS

32

dBm

46.5

dBi 103m/

22.6km LMR-

600

152.6

dB 12 dBm

-68.0

dBm

007 00 00 E 118m

Coax at

110m

04 39 29.40 N 14.29 dB

006 36 35 E

Ughelli / Afiesere LOS

32

dBm

46.5

dBi

72m/68

m

31.84km LMR-

600 165 dB 13.7 dBm

-66.3

dBm

05 29 19 N

Coax at

78m

006 00 24 E 6.43 dB

05 19 59 N

006 14 59 E

Diebu creek / Nun

River

LMR-

900

05 03 36 N 112m/

Coax at

120m

006 27 17.60 E LOS

32

dBm

46.5

dBi 118m

11.50 dB

153.3d

B 11.2 dBm

-68.8

dBm

04 53 23 N 25.4km

006 22 22 E



Fig 3 Odeama creek /Soku displayed on land use Fig 4 Odeama creek/Soku stations displayed

on administrative boundaries. land cover showing the legend.

4. RESULTS AND DISCUSSION

Figure 2 shows a screen capture of the form view of the

path loss calculation interface.

The program was tested with a previous research done

and the results were compared with the output of the

application. Table 1 below summarizes the results

obtained (Edeh, 2008)

From this legend, it is clear that that Odeama creek and

Soku (a built up area) are separated basically by Tall

Mangrove forest. This alongside other attenuation factors

explains the high value of path loss calculated, thus the

received signal will be low if measures are not taken to

improve signal quality. This makes better understanding

than when it is merely described with words. Even before

going to do real field survey, preliminary planning can be

done based on this analysis.

Figure 4 above shows Odeama creek/Soku stations

displayed on administrative boundaries and river layer.

This is necessary for the planner to know the

administrative delineations so he can plan towards

complying with the respective state and local government

statutory requirements.

Figure 5 shows Ughelli/Afiesere stations and computed

pathloss displayed on land use land cover. Using the

legend in fig 3 it is clear that Ughelli and Afiesere are

separated by heavy forests which include palm, rubber

etc. This alongside other attenuation factors explains the

high value of path loss calculated, thus the received signal



will be low if measures are not taken to improve signal quality.

Fig 5 Ughelli/Afiesere stations displayed on LULC Fig 6 Diebu creek/Nun River stations and Calculated

pathloss displayed on land use land cover.

It is clear that Diebu Creek and Nun River are separated

by mangrove and forests as seen in fig 6. This alongside

other attenuation factors explains the high value of

pathloss calculated, thus the received signal will be low if

measures are not taken to improve signal quality.

5. CONCLUSION

While classic path loss models alone can form the basis of

correct analysis, it only relies on descriptions of terrain

and other geographical parameters which are quite

important. Thus, the planner in the office, who never went

to the field, may not have a visual description of the

terrain, distance between transmit and receiving stations

and other geographical parameters. This paper addressed

this problem using Geographic Information Systems,

customized for this purpose. The visual and spatial

handling capabilities brought an extra edge into the study

of path loss analysis. Thus achieving the same result

(faster) but with an extra advantage of allowing the

planner see the terrain parameters from his desktop while

making accurate decisions. Apart from this, certain other

analysis (Proximity, Network and Overlay) can be used to

further simplify the work of the telecommunications

engineer.

REFERENCES

[1] Okumura, Y. (1968). Field strength and it’s

variability in VHF and UHF land-mobile radio-

services. Review of the Electrical Communications

Laboratory, vol. 16.

[2] Baldassaro,P.M, Bostian.C.W, Carstensen.L.M, and

Sweeney.D.G (2002): “Path Loss Predictions and

Measurements over urban and rural terrain at

frequencies between 900 MHz and 28 GHz.” Proc.

IEEE AP-S2002 International Symposium, in press.

[3] Neskovic .A(2000); Modern Approaches in Modeling

of Mobile Radio Systems Propagation Environment;

IEEE Communiation Surveys.

[4] Lee, W. C. Y(1998): Mobile Communications

Engineering: Theory and Applications, McGraw-

Hill, 1998.

[5] Hata, M. (1980); Empirical Formula for Propagation

Loss in Land Mobile Radio Services; IEEE Trans.

Vehicular Technology.

[6] Sweeney, D (2003); Propagation Issues for Land

Mobile Radio (LMR) in the 100 to 1000 MHz

Region; Center for Wireless Telecommunications,

Virgin

[7] 231 Final Report, Digital Mobile Radio(1990): COST

231 View on the Evolution Towards 3rd Generation

Systems, Commisiion of the European Communities

and COST Telecommunications, Brussels, 1999.

[8] Edeh, P.O (2008); Path Loss Model for Microwave

radio link in Southern part of Nigeria; University of

Port Harcourt



[9] Prasad. M.V.S.N and A. Iqbal (1997): “Comparison

of some path loss prediction methods with

VHF&UHF measurements”, IEEE Transactions On

Broadcasting, Vol. 43, No. 4, pp. 459-486, 1997.

[10] Rama.T, Rao, S. Vijaya Bhaskara Rao, M.V.S.N.

Prasad, Mangal Sain, A. Iqbal, and D. R.

Lakshmi(2000): “Mobile Radio Propagation Path

Loss Studies at VHF/UHF Bands in Southern India”,

IEEE Transactions On Broadcasting, Vol. 46, No. 2,

pp. 158-164, 2000.

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Journal of Engineering Path Loss Model Using Geographic ... · of the link budget of a telecommunication system. It is the ... and the calculated pathloss displayed. This was overlayed