Comparative Path Loss Analysis Of Okumura And COST 231 Models For Wireless Mobile Communication Using MATLAB Simulation

Comparative Path Loss Analysis Of Okumura And COST 231 Models For Wireless Mobile Communication Using MATLAB Simulation

Saptarshi Gupta

Department of Electronics & Communication Engineering, All Nations University College, Koforidua, Ghana, West Africa

Abstract

Now a days mobile communication is very much essential for interchanging informations. Mobile communication use radio signal for voice transmission. When radio signal propagates in free space it suffers with attenuation, fading, distortion. Here transmitting antenna height also plays a great role in path loss. In mobile communication handoff is depend upon received signal strength. For proper planning different service providers use different models such as Okumura and COST 231 models. This paper deals with comparative analysis of these two models.

Keywords- okumura model, COST 231, matlab

1. Introduction

   The strength of electromagnetic wave decreases as it propagates through space, this happens due to losses exist in path. The signal path loss affects many parameters of the radio communications. Due to this, it is necessary to recognize the reasons for radio path loss, and to be able to determine the levels of the signal loss for a given radio path [1]. Path loss plays vital role to decide the QoS for wireless communication at network planning level. Path loss causes poor signal strength at the receiver side [1].

   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 [2].

2. Path Loss: Models of "large-scale effects"

   The most appropriate path loss model depends on the location of the receiving antenna. For the example below at:

   Figure 1. Path loss model depends on the location of the receiving antenna.

   location 1, free space loss is likely to give an accurate estimate of path loss.

   location 2, a strong line-of-sight is present, but ground reflections can significantly influence path loss. The plane earth loss model appears appropriate.

   location 3, plane earth loss needs to be corrected for significant diffraction losses, caused by trees cutting into the direct line of sight.

   location 4, a simple diffraction model is likely to give an accurate estimate of path loss.

   location 5, loss prediction fairly difficult and unreliable since multiple diffraction is involved [3].

3. Propagation Models:

   Propagation models that predict the mean signal strength for an arbitrary transmitter-receiver separation distance are useful in estimating the radio coverage area of a transmitter and are called large-scale propagation model. On the other hand, propagation models that characterize the rapid fluctuations of the received signal strength over very short travel distances or short time durations are called small scale or fading models [4].

   The well known propagation models for urban areas are Okumura model and COST 231 model.

   1. Okumura model:

      The Okumura model for urban areas is a Radio propagation model that was built using the

      data collected in the city of Tokyo, Japan [5]. This model is applicable for frequencies in the range of 150 MHz to 1920 MHz and distances of 1 km to 100 km. It can be used for the base stations antenna heights ranging from 30 m to 1000 m. To determine path loss using Okumaras model, the free space path loss between the points of interest is

      hm = hr hm m

      L0 10 0.354

      L0 2.5 0.075( 35)dB

      L0 4 0.114( 55)dB

      0 350

      350 550

      550 900

      first determined and then the value of Amu (f, d) is added to it along with correction factors according to the type of terrain. The model can be expressed as [4]:

      L50 (dB) = LF + Amu (f, d) G (hte) G (hre) – GAREA

      Where,

      L50 is the 50th percentile path loss in dB.

      Where:

      = incident angle relative to the street

      The multiscreen (multiscatter) loss is given as: Lms Lbsh ka kd log d k f log fc 9log b Where:

      b = distance between building along radio path (m)

      d = separation between transmitter and receiver (km)

      LF is the free space propagation loss in dB. Amu (f, d) is median attenuation in dB.

      G (hte) is the base station antenna height gain

      Lbsh 18log(11 hb )

      Lbsh 0

      hb hr hb hr

      factor.

      G (hre) is the mobile antenna height gain factor. GAREA is the gain due to the type of environment. Moving from urban to suburban or open area [4].

      hte

      Where: hb hb hr , height (m)

      ka 54

      k 54 0.8h

      hr = average buildings

      hb hr

      d 500m; hb hr

      G(hte ) 20 log( 200) ; 1000m hte 30m a b

      G(h ) 10 log( hre ) ; h 3m

      ka 54 0.8hb (d / 500) d 500m; hb hr

      re 3 re

      Both Lbsh and ka increase path loss with lower

      G(h ) 20 log( hre ) ; 10m h

      3m

      base station antenna heights.

      re 3 re

      k 18

      h h

      d b r

   2. COST 231 model:

      k 18 15hb

      h h

      This model [6] is a combination of empirical and deterministic models for estimating the path loss in an urban area over the frequency range of 800 MHz to 2000 MHz. The model is used

      hm

      d

      d

      b r

      b r

      kf 4 0.7( fc / 925 1) for mid-size city and suburban area with moderate tree density

      primarily in Europe for the GSM 1800 system.

      k f 4 1.5(

      fc

      925

      1) for metropolitan area

      L50 Lf Lrts LmsdB

      Where:

      The range of parameters for which the COST 231 model is valid is:

      Lf = free space loss (dB)

      800 fc 2000MHz

      Lrts = roof top to street diffraction and scatter loss (dB)

      L = multiscreen loss (dB)

      4 hb 50m 1 hm 3m

      ms

      Free space loss is given as:

      0.02 d 5km

      Lf 32.4 20log d 20log fcdB

      The roof top to street diffraction and scatter loss is given as:

      Lrts 16.9 10logW 10log fc 20log hm L0dB

      Where:

      W= Street width (m)

      The following default values may be used in the model:

      b 20 50m W b /2

      900

      Roof = 3 m for pitched roof and 0 m for flat roof, and hr 3 (number of floors) + roof

      In this paper, the performance analysis of Okumura and COST 231 models such as Path loss versus Base station antenna height with different T- R distance, Path loss versus T-R distance with different base station antenna heights, has been compared considering the system to operate at 900 MHz.

4. Simulations and parameters:

   Simulations were done in MATLAB 7.5 software.

   Path loss versus T-R distance with different base station antenna heights (Okumura) 25

   20

   Path loss (dB)

   Path loss (dB)

   15

   10

   5

   0

   -5

   -10

   -15 Base st Ant Ht= 30 m

   Base st Ant Ht= 40 m

   Sl No	Parameters	Values
   1	Base station transmitter power	43 dBM
   2	Mobile transmitter power	30 dBM
   3	Base station antenna height	30-50 m
   4	Mobile antenna height	3 m
   5	Frequency/Carrier Frequency fc	900 MHz

   Sl No	Parameters	Values
   1	Base station transmitter power	43 dBM
   2	Mobile transmitter power	30 dBM
   3	Base station antenna height	30-50 m
   4	Mobile antenna height	3 m
   5	Frequency/Carrier Frequency fc	900 MHz

   -20

   Base st Ant Ht= 50 m

   1 1.5 2 2.5 3 3.5 4 4.5 5

   Distance between base station and mobile (Km)

   Figure 3. Path loss versus T-R distance with different base station antenna heights (Okumura)

   						T-R Distance= 1 Km T-R Distance= 2 Km T-R Distance= 3 Km T-R Distance= 4 Km T-R Distance= 5 Km

   						T-R Distance= 1 Km T-R Distance= 2 Km T-R Distance= 3 Km T-R Distance= 4 Km T-R Distance= 5 Km

   Path loss versus Base station antenna height with different T-R distance (COST231) 220

   215

   Path loss (dB)

   Path loss (dB)

   210

   205

   200

   1. Simulation Results and comparison:

      Path loss versus Base station antenna height with different T-R distance (Okumura) 25

      T-R Distance= 1 Km

      20 T-R Distance= 2 Km

      T-R Distance= 3 Km

      195

      190

      185

      180

      30 32 34 36 38 40 42 44 46 48 50

      Base station antenna height (m)

      15 T-R Distance= 4 Km

      Path loss (dB)

      Path loss (dB)

      T-R Distance= 5 Km

      10

      5

      Figure 4. Path loss versus Base station antenna height with different T-R distance (COST231)

      0

      -5

      -10

      -15

      -20

      30 32 34 36 38 40 42 44 46 48 50

      Base station antenna height (m)

      Figure 2. Path loss versus Base station antenna height with different T-R distance (Okumura)

      Path loss versus T-R distance with different base station antenna heights (COST231) 220

      					Base st Ant Ht= 30 m Base st Ant Ht= 40 m Base st Ant Ht= 50 m

      					Base st Ant Ht= 30 m Base st Ant Ht= 40 m Base st Ant Ht= 50 m

      215

      Path loss (dB)

      Path loss (dB)

      210

      205

      200

      195

      190

      185

      180

      1 1.5 2 2.5 3 3.5 4 4.5 5

      Distance between base station and mobile (Km)

      Figure 5. Path loss versus T-R distance with different base station antenna heights (COST231)

      250

      200

      150

      T-R Distance= 1 Km (COST231) T-R Distance= 2 Km (COST231)

      T-R Distance= 3 Km (COST231) T-R Distance= 4 Km (COST231)

      Path loss (dB)

      Path loss (dB)

      T-R Distance= 5 Km (COST231)

      the graph it is seen that for Okumura model the path loss is lowest.

5. Conclusion:

The simulation results show the amount of path loss by varying the base station antenna height from 30 to 50 m and the varying separation between base station & mobile from 1 to 5 Km.

100 T-R Distance= 1 Km (Okumura)

T-R Distance= 2 Km (Okumura) T-R Distance= 3 Km (Okumura)

Path loss decrease with the increase in base station antenna height and increases with the increase in T-

50

0

-50

T-R Distance= 4 Km (Okumura) T-R Distance= 5 Km (Okumura)

R distance. From the graph it is seen that Okumura

model shows the better performance than COST 231 model. The result of this work gives an idea for telecomm engineer to choose the appropriate model for efficient wireless mobile communication.

30 35 40 45 50

Base station antenna height (m)

Figure 6. Comparison of Okumura Model and COST231 model (Path loss versus base station antenna heights with different T-R distance)

250

200

References:

1. Dinesh Sharma, R.K.Singh, The Effect of Path Loss on QoS at NPL International Journal of Engineering Science and Technology Vol. 2(7), 2010, 3018-3023.

2. http://en.wikipedia.org/wiki/Path_loss, January, 2013. [3]Jean-Paul M. G. Linmartz's, Wireless Communication, The Interactive Multimedia CD-ROM, Baltzer Science Publishers, P.O.Box 37208, 1030 AE Amsterdam, ISSN 1383 4231, Vol. 1 (1996), No.1

   Path loss (dB)

   Path loss (dB)

   150

   100

   50

   0

   Base st Ant Ht= 30 m(COST231)

   Base st Ant Ht= 40 m(COST231) Base st Ant Ht= 50 m(COST231) Base st Ant Ht= 30 m (Okumura) Base st Ant Ht= 40 m(Okumura) Base st Ant Ht= 50 m(Okumura)

   (http://people.seas.harvard.edu/~jones/es151/prop_model s/propagation.html)

   1. Theodore.S.R., 2006, Wireless Communications Principles and Practice, Prentice-Hall, India.

   2. http://en.wikipedia.org/wiki/Okumura_Model,

   3. Walfisch, J., and Bertoni, H. L. A Theoretical Model of UHF Propagation in Urban Environment. IEEE Transactions, Antennas & Propagation, AP-36:1788 1796, October 1988.

-50

1 1.5 2 2.5 3 3.5 4 4.5 5

Distance between base station and mobile (Km)

Figure 7. Comparison of Okumura Model and COST231 model (Path loss versus T-R distance with different base station antenna heights)

Figure 2 & 4, shows that the path loss decreases due to the increase in base station antenna height with different T-R distances for Okumura and COST 231 models.

Figure 3 & 5, shows that the path loss increases due to the increase in distance between base station and mobile with different base station antenna heihts for Okumura and COST 231 models.

Figure 6 shows the Comparison of Path loss versus base station antenna heights with different T-R distance for Okumura Model and COST231 model. From the graph it is seen that for Okumura model the path loss is lowest.

Figure 7 is the Comparison of Path loss versus T-R distance with different base station antenna heights for Okumura Model and COST231 model. From

Mr. Saptarshi Gupta received the B.Tech. degree in Electronics and Communication Engineering from IMPS College of Engineering & Technology affiliated to West Bengal University of Technology, West Bengal, India in 2008, and M.Tech. degree in Digital communication and Networking from SRM University, Chennai, India in 2010. Since 2010, he is working as a Lecturer in the Department of Electronics & Communication Engineering, All Nations University College, Koforidua, E/R, Ghana, West Africa. His research interests include Digital Communication, Queuing Theory, Microwave & Optical communication and Wireless Communication.