Electromagnetic Propagation Environment Effects On The WiMAX Communication System

7/30/2019 Electromagnetic Propagation Environment Effects On The WiMAX Communication System

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Electromagnetic Propagation Environment Effects On

The WiMAX Communication System1Hani Wadie Badri,

1Said Ghnimi,

1Ali Gharsallah

1Unité de Recherche: Circuits et Systèmes Electroniques HF, Faculté des Sciences de Tunis, FST

[email protected], [email protected], [email protected]

Abstract — The goal of this paper is to study the electromagnetic

environment of WiMAX (worldwide interoperability for

microwave access) communication system working at 3.5 GHz.

For this, we have analyzed and compared the radio signal loss in

urban, suburban and rural environment with different receiver

antenna height. The path loss prediction is obtained by three

propagation models: SUI (Stanford University Interim), COST

Hata and Ericsson model. The analysis was made using

MATLAB software. The results shows that in general SUI model

predict the lowest path loss, especially in suburban environments.

Keywords; WiMAX, path loss, propagation models, SUI,

COST Hata, Ericsson.

I. Introduction

WiMAX is a certification mark for products based on

the IEEE 802.16 standard [1-11] this system is a

telecommunications technology which enables wireless

transmission of voice and data and provide wireless access in

urban, suburban and rural environment with non line of sight

(NLOS) propagation [2]. This scenario of propagation

introduce multipath, which decreases the signal strength [3].

In this case an estimation of the path loss is necessary to

compensate the power propagation of the signal. There ismany path loss models used to predict the path loss indifferent environment in this paper we have chose to study

three models: SUI, COST Hata and Ericsson model.

In the literature several works are edited to evaluate

the fixed and mobile WiMAX system. In a previous study

Snježana Rimac-Drlje [4] analyzed empirical models

suitability for the receiving power prediction in complex urban

environments for a WiMAX system working at 3.5 GHz of

city Osijek in Croatia. He had used four propagation models:

SUI, COST 231-Hata, Macro model and Ericsson model.

Similar studies were also conducted by Mardeni.R [3] in

Malaysia at the bands of 2360-2390MHz, Purnima K. Sharma

[5] in India at 900 MHz and 1800 MHz frequency. Bachir Belloul [2] studied the performance of co-located WiMAX

transmitter sites operating at 2.5 and 3.5GHz. Nickolas

LaSorte [6] presents an evaluation of a deployed WiMAX

system operating in the 4.9GHz Public Safety Band in the City

of Tulsa.

Therefore, the organization of this paper is as

follows, in section II, the theoretical formulation of the tree

models (SUI, COST Hata and Ericsson model) is given, in

section III, we present the results and discussion of path loss

prediction in different environments and section IV contains

conclusion and recommendations for further studies.

II. Formulation

A. Stanford University Interim (SUI) Model

The SUI prediction model is developed under the IEEE802.16 Broadband Wireless Access Working Group.

This model is useful for WiMAX systems with small cells, BSat low heights and high frequencies. The SUI model is

optimized for a frequency of 1.9 GHz [6]. The correction

parameters are allowed to extend this model up to 3.5 GHz

band [4].In general, for all types of terrain, the path loss is given by the

following equation [7].

10 010 log ( ) f h

o

d PL A X X s ford d

d γ = + + + + > (1)

Where the parameters are [7-8]

010

420 log

d A

π

λ

⎡ ⎤= ⎢ ⎥

⎣ ⎦ (2)

λ : the wavelength (m)

And γ the path loss exponent is given by [8]

b

b

ca b h

hγ = − + (3)

γ = 2 for free space propagation in urban environment, inurban NLOS environment 3<γ<5, and for indoor propagationγ>5 [4]

od =100 m

d: distance between the BS and receiving antenna (m)

bh : base station antenna height (m)S : correction for shadowing (dB)

The values of constants a, b and c depend on the terrain

category as defined in Tab.1 [9].



Tab.1: Values of constants a, b and c of the SUI model [9].

SUI

parameters

Terrain ATerrain B Terrain C

a 4.6 4 3.6

0.0075 0 .0065 0.005

c 12.6 17.1 20

The frequency correction factor f X and the correction for

receiver antenna heighth X for the model are expressed in [9].

1 06 l o g ( )2 0 0 0

f

f X =

(4)

(5)

Where

f : Frequency [MHz]

r h : Height of receiver antenna [m]

B. COST-231 Hata model

COST Hata model is an extension of the Hata-Okumuramodel [3, 8]. This model is used for macros cells, it is mainlydone for frequencies below 2 GHz [5]. In order to use it for

higher frequencies (up to 6 GHz) he was introducedcorrections. The COST Hata model path loss in dB equation isgiven by [8].

10 10

10

46.3 33.9 log ( ) 13.82 log ( )

(44.9 6.55 log( )) log

b m

b m

PL f h ah

h d c

= + − −

+ − +

(6)

d: distance [km]

f: frequency [MHz]

bh : base station antenna height [m]

mc Constant term ( mc = 0 dB in suburban and rural areas,

mc = 3 dB in urban areas).

ma h is a corrective term depending on the height of the

receiving antenna.

─ For an urban environmentmah is:

2

103.20(log (11.75 )) 4.79 400m r ah h for f MHz = − > (7)

─ For suburban and rural environmentsmah is:

10 10(1.11log ( ) 0.7) (1.5 log 0.8)m r ah f h f = − − − (8)

Wherer

h is the receiver antenna height.

C. Ericsson model

Ericsson model or also model 9999 [2-4] is provided byEricsson company. He is an extension of Hata model, his parameters are changeable according to the propagationenvironment. The path loss in dB given by Ericsson model isthe following equation [7].

0 1 10 2 10 3 1 0 10

2

10

. log ( ) .log ( ) log ( ).log ( )

3.2(log (11.75 ) ) ( )

b b

r

PL a a d a h a h d

h g f

= + + +

− + (9)

( ) g f is given by the expression

2

10 10( ) 44.49log ( ) 4.78(log ( )) g f f f = − (10)

Where f : Frequency [MHz]

r h : Transmitter antenna height [m]

bh : Receiver antenna height [m]

The parameters0

a ,1

a ,2

a and3

a are constants depend on

the environment of propagation their values are given by thetab. 2 [10]

Tab. 2: Values of 0a ,

1a ,2a and

3a of Ericsson model [10]

Ericsson

parameters0a

1a 2a

3a

urban 36,2 32,2 12,0 0,1

suburban 43,20 68,93 12,0 0,1

rural 45,95 100,6 12,0 0,1

III. SIMULATION R ESULTS A ND DISCUSSION

The simulation parameters are presented in the Tab.3

Tab.3: Simulation parameters

Parameters Values

Base station transmission power 43 dBm

Receiver antenna power 30 dBm

Transmitter antenna height40 m in urban and suburban environments

and 30 m in rural environment

Receiver antenna height 2 m and 8 m

Frequency 3.5 GHz

Distance between Rx and Tx 5 km

Correction for shadowing8.2 dB in suburban and rural environments

and 10.6 dB urban environment

10

10

10.8log ( )2000

20log ( )2000

r

r

h for terrain A and B

h h for terrain C

X −

−

⎧= ⎨

⎩



We have used these parameters to calculate the path loss indifferent propagation environments.

A. Results in urban environment

The results of path loss for different models at 2m and 8mreceiver antenna height in urban environment are presented in

the Fig. 1.

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 590

100

110

120

130

140

150

160

170

180

distance between Tx and Rx (km)

p a t h

l o s s

( d B )

path loss in urban environment

sui 2m

sui 8m

COST Hata 2m

COST Hata 8m

Ericsson 2m

Ericsson 8m

Fig.1: Path loss of different models in urban environment

The Tab.4 shows the path loss at 3 km distance between thetransmitting and receiving antenna in urban environment.

Tab.4: Path loss values at 3 km distance in urban environment

SUI COST Hata Ericsson2m 153 162,7 146,5

8m 140,9 156,2 142,6

From these results we can see that the Ericsson model

predict the lowest path loss when the receiver antenna height is2m (146.5 dB). By changing the receiver antenna height to 8m,note that the SUI model showed the lowest prediction (140.9dB). The path loss showed by the COST Hata model is thehighest in the both cases 2 and 8m. The effect of the changingof the receiver antenna height is more remarkable for the SUImodel, the prediction of path loss has decreased from 153 dB at

2m to 140.9 dB at 8m, but in case of Ericsson and COST Hatamodels it has not much influence.

B. Results in suburban environment

The results of path loss for different models at 2m and 8m

receiver antenna height in suburban environment are presentedin the Fig. 2.

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 560

80

100

120

140

160

180

200


p a t h

l o s s

( d B )

path loss in suburban environment

sui 2m

sui 8m

COST Hata 2m

COST Hata 8m

Ericsson 2m

Ericsson 8m

Fig.2: Path loss of different models in suburban environment

The Tab.5 presents the path loss at 3 km distance betweenthe transmitting and receiving antenna in suburbanenvironment.

Tab.5: Path loss values at 3 km distance in suburban environment

SUI COST Hata Ericsson

2m 126,9 158,8 172

8m 120,4 139.4 168,1

By observing the graphical representation of simulation

shown in Fig.2 and the values of path loss at 3 km distance inthe Tab.5. We concluded that the SUI model shows the lowest path loss prediction in both cases (2m, 8m) of receiver antennaheight respectively (126.9 dB, 120.4 dB). The Ericsson model

predicts the highest path loss (172 dB, 168.1 dB). In suburbanenvironment the changing of receiver antenna height has ahuge effect on the COST Hata model prediction compare to

other models, the path loss has decreased from 158.8 dB at 2mto 139.4 dB at 8m.

C. Results in rural environment

The results of path loss for different models at 2m and 8mreceiver antenna height in rural environment are presented in

the Fig. 3.



0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 560

80

100

120

140

160

180

200

220


p a t h l o

s s

( d B )

path loss in rural environment

sui 2m

sui 8m

COST Hata 2m

COST Hata 8m

Ericsson 2m

Ericsson 8m

Fig.3: Path loss of different models in rural environment

The Tab.6 shows the values of path loss at 3 km distance in

rural environment.

Tab.6: Path loss values at 3 km distance in rural environment

SUI COST Hata Ericsson

2m 153 ,8 160,9 191,3

8m 141,5 141,5 187,5

In this environment, at 2m receiver antenna height, SUImodel showed the lowest path loss prediction (153,8dB). At8m receiver antenna height both the COST Hata and SUI

models showed the lowest path loss (141,5dB). The path lossgiven by Ericsson model is very far from that given by theothers models (191.3 dB, 187.5 dB). Increase the receiver

antenna heights decreased the path loss for SUI and COSTHata models but not for Ericsson model.

IV. CONCLUSION

In this work, we have evaluated the path loss prediction of three different propagation models in urban,suburban and rural environment for WiMAX system on 3.5GHz frequency. The result of analysis allows us to see that the

path loss prediction given by the propagation models used in

this study depends on the type of environment of propagationand the receiver antenna height. The results shows that at 3.5

GHz, the SUI model give the lowest prediction, especially insuburban environment and increase the receiver antennaheight will decrease the path loss.

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