okumura, hata and cost231 propagation models

FBE104 Wireless Communications and Mobile Systems

KOCAELI UNIVERSITY

Graduate School of

Natural and Applied Sciences

Prepared By: Mohammed ABUIBAID

Email: [email protected]

Submitted to: Dr. Kerem KÜÇÜK

Electronic and Communication Engineering

OKUMURA, HATA and COST231 Propagation Models

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Presentation Outline1. Kinds of Propagation Models

2. Models of Different Types of Cells

3. Web Plot Digitizer Tool

4. Study of the parameters fc, d, 𝒉𝒃 , 𝒉𝒎 and Coverage

Environments for each of OKUMURA, HATA and COST231

5. MATLAB Simulation

Empirical models

Three kinds of models Semi-deterministic models

Deterministic models

Empirical models : based on measurement data, simple (few parameters), use

statistical properties, not very accurate

Semi-deterministic models : based on empirical models + deterministic aspects

Deterministic models : site-specific, require enormous number of

geometry information about the cite, very important computational effort, accurate

Propagation Models

Models of Different Types of Cells :

Macro-cell path loss models Empirical models: Okumura-Hata model, COST 231-Hata model

Semi-empirical models: COST 231-Walfisch-Ikegami

Deterministic models: Plane earth model, Ikegami model

Microcell path loss modelsEmpirical model: Dual slope empirical model

Deterministic model: Two-ray model

Pico-cell path loss modelsEmpirical model: Wall and floor factor models - ITU-R models

Semi-empirical model: COST231 line-of-sight model

Okumura Model

Widely used for signal prediction in urban areas

Applicable for:

• Frequency f: 150 MHz to 1920 MHz (it is typically extrapolated up to 3000 MHz)

• Distance d: 1 km to 100 km

• Transmit antenna effective height : 30 m to 1000 m and Mobile Antenna height 1 m to 10 m

Based on extensive measurements

Technique

• Find free space path loss, LF (using equation)

• Determine median attenuation relative to free space Amu(f,d) (from curves)

• Add correction gain factors for transmitter and receiver antenna heights (from curves or using their equations) and area gain factor (from curves)

Okumura Model

𝑳𝟓𝟎 𝒅𝑩 : the 50th percentile (i.e., median) value of propagation path loss between the TX and RX expressed in dB

𝑳𝑭 : is the free space propagation loss in dB

𝑨𝒎𝒖(f, d) : the median attenuation relative to free space additional losses in dB due to propagation in urban environment when TX and RX at referenced heights.

𝑮(𝒉𝒕𝒆) : the base station antenna height gain factor in dB

𝑮(𝒉𝒓𝒆) : the mobile antenna height gain factor in dB

𝑮𝑨𝑹𝑬𝑨: the gain due to the type of terrain in dB

Okumura Model (free space loss)

d Distance between the TX and RX in km

f Operating frequency in MHz

𝑮𝒕 TX antenna gain (linear)

𝑮𝒓 RX antenna gain (linear)

The remaining terms of Okumura Model are provided in a graphical form as the family of curves.

Okumura Model (Basic Median Attenuation 𝑨𝒎𝒖(f, d) )

It models additional propagation losses due to the signal propagation with these referencedconditions:- Terrestrial Urban environment over a quasi-smooth terrain.- Base station Effective antenna height 𝒉𝒕𝒆 = 𝟐𝟎𝟎𝒎- Mobile antenna height 𝒉𝒓𝒆 = 𝟑𝒎.

If the actual heights of the TX and RX or the propagation area type differ from those referenced, the appropriate correction needs to be added.

Okumura Model (Base Station Effective Height Gain 𝑮 𝒉𝒕𝒆 )

At the effective height of 200m, all curves meet and no correction gain is required (𝑮 𝒉𝒕𝒆 = 𝟎 𝒅𝑩)

Base station antennas above 200m, introduce positive gain and antennas lower than 200m have negative gain factor.

The parameter of the family of the curves is the distance between the transmitter and receiver.

Okumura found that 𝑮 𝒉𝒕𝒆 varies at a rate of 20 dB/decade for effective heights between 30 m and 1000 m

Okumura Model (Effective Transmitter Antenna Height)

The terrain is averaged along the direction of radio path over the distances between 3 and 15 kilometers.

Effective antenna height is determined as the difference between the height of the BTS antenna and the height of the average terrain.

Okumura Model (Mobile Height Gain Factor 𝑮 𝒉𝒓𝒆 )

All curves meet at the referent 3m horizontal coordinate.

Higher antennas introduce gain and lower cause loss of referent signal level.

The parameter for this family of curves is operating frequency.

Mobile height gain factor is also separated according to the size of the city in two clusters: medium and large cities.

Okumura found that 𝑮 𝒉𝒓𝒆 varies at a rate of 10 dB/decade for Mobile heights less than 3 m and varies at a rate of 20 dB/decade for Mobile heights between 10 and 3 m.

Okumura Model (Environment Gain 𝐺𝐴𝑅𝐸𝐴)

For the referent Urban terrain environment the

value of 𝐺𝐴𝑅𝐸𝐴 = 0 𝑑𝐵.

For Other terrain types; such as Suburban, Quasi-

Open and Open Areas, the value of 𝐺𝐴𝑅𝐸𝐴 can be

read the curves.

𝐺𝐴𝑅𝐸𝐴 values represent a additional loss

correction factor due to propagation in different

than Urban environment.

Okumura Model (Optional Correction Factors)

Some of the important terrain related corrections parameters are:

- Terrain undulation height Δh

- Isolated ridge height

- Average slope of the terrain

- Mixed land-sea parameter

Once the terrain related parameters are calculated, the necessary correction factors can

be added or subtracted as required.

Okumura Model (Pros and Cons)

Okumura's model is wholly based on measured data and does not provide any analytical explanation.

For many situations, extrapolations of the derived Curves can be made to obtain values outside the measurement range.

The validity of such extrapolations depends on the circumstances and the smoothness of the curve in question.

The major disadvantage is its slow response to rapid changes in terrain.

The model is fairly good in urban and suburban areas, but not as good in rural areas.

Common standard deviations between predicted and measured path loss values are around 10 dB to 14 dB.

Web Plot Digitizer Tool

WebPlotDigitizer is a free, online/offline tool to extract numerical data from plots, images and maps.

WebPlotDigitizer release notes are available here. The user manual is available here.

This tool can be employed to read values form OKUMURA Curves to use them in path loss calculations.

http://arohatgi.info/WebPlotDigitizer/app/release_notes.txt

http://arohatgi.info/WebPlotDigitizer/userManual.pdf

Okumura Model: Figure 1

Variable Parameter:

d = [1 2 3 5 10 20 30 40 50 60 70 80 90 100]Amu=[20.5 ….. 61]*

Constant Parameters:

f=1000, hb=200, hm=3, Urban

The path loss increase exponentially as the Tx,Rxseparation distance increase.

*: This values are read from Okumura Curves using Web Digitizer Tool


Variable Parameter:

f =150.23, …. 1916.29*

Amu =28.15, …. 36.27*


d=20, hb=200, hm=3, Urban

Area.

The path loss increase linearly

as the operating frequency

increase.

*: This values are read from

Okumura Curves using Web

Digitizer Tool


Variable Parameter:

hb = 30:0.5:1000


f=1000, d=20, hm=3, Amu=

32.9*, Urban Area.

The path loss decrease

exponentially as the BS

Effective Height increase.



Digitizer Tool


Variable Parameter:

hm = 1:0.2:10


f=1000, d=20, hb=200,

Amu= 32.9*, Urban Area.


exponentially as the MS

Antenna Height increase.



Digitizer Tool


Variable Parameter:G_area = { G_suburban = 9.82, G_quasi-open areas = 23.28,G_open areas = 28.63 }*


f=1000, d=20, Amu= 32.9*, hb=200, hm=3

The path loss decrease linearly as the coverage area change from suburban to open areas.

*: Theses values are read from Okumura Curves using Web Digitizer Tool

Okumura-Hata Model Simply, It represents a curve fitting of Okumura’s original results.

Applicable for:

• Transmit antenna effective height : 30 m to 200 m and Mobile Antenna height 1 m to 10 m

• Frequency f: 150 MHz to 1500 MHz and TX RX Distance d: 1 km to 20 km

In that implementation, the path loss is written as

Okumura-Hata Model ( 𝐚(𝐡𝐦) , C Factor )

The function 𝑎(ℎ𝑚) and the factor C depend on the environment:

𝒂(𝒉𝒎) in suburban and rural areas is the same as for urban areas (small & medium-sized cities)

Okumura-Hata Model: Figure 6

Variable Parameter:

d = 1:0.2:20


f=1000, hb=50, hm=3,

Enviro=Urban

The path loss increase

exponentially as the Tx,Rx

separation distance increase.


Variable Parameter:

f = 150:20:1500


d=15, hb=50, hm=3,

Enviro=Urban


linearly as the operating

frequency increase.


Variable Parameter:

hb = 30:2:200


d=15, f=1000, hm=3,

Enviro=Urban





Variable Parameter:

hm = 1:0.2:10


d=15, f=1000, hb=50,

Enviro=Urban


linearly as the MS Antenna

Height increase.


Variable Parameter:

Environment = { Urban,

Metropolitan, Suburban, Rural

}


d=15, f=1000, hb=50,

hm=3, Enviro=Urban


dramatically as the coverage

area change from

Metropolitan to Rural

Okumura-Hata Model (Pros and Cons)

It was derived as a numerical fit to the curves published by Okumura. As such, the model is somewhat specific to Japan’s propagation environment.

It assumes that there are no dominant obstacles between the BS and the MS, and that the terrain profile changes only slowly.

Measurements have shown several disadvantages to the approach for effective antenna height calculation. To circumvent the problem, some prediction tools examine alternative methods for calculation of the effective antenna height.

Parameter range does not encompass the 1800 MHz frequency range most commonly used for 2G and 3G cellular systems. (This was solved by the COST 231-Hata model)

COST 231-Hata Model Extends the validity region of Okumura-Hata Model to 1500 - 2000 MHz range which

encompass the 1800 MHz frequency which is used for 2G and 3G cellular systems.

COST 231-Hata Model defined by:

C is 0 in small and medium-sized cities “Urban Areas”, and Suburban Areas.

C is 3 in Metropolitan Areas.

COST231-HATA MODEL: Figure 11

Variable Parameter:

d = 1:0.2:20


f=1800, hb=50, hm=3,

Enviro=Urban


exponentially as the Tx,Rx

separation distance increase.


Variable Parameter:

f = 1500:20:2000


d=15, hb=50, hm=3,

Enviro=Urban


linearly as the operating

frequency increase.


Variable Parameter:

hb = 30:2:200


d=15, f=1800, hm=3,

Enviro=Urban





Variable Parameter:

hm = 1:0.2:10


d=15, f=1800, hb=50,

Enviro=Urban


linearly as the MS Antenna

Height increase.


Variable Parameter:

Environment = { Urban,

Metropolitan, Suburban}


d=15, f=1800, hb=50,

hm=3

The difference between

Urban/Suburban Areas and

Metropolitan is 3 dB.

References

[1] The Mobile Radio Propagation Channel, 2nd Edition by J. D. Parsons

[2] Wireless Communications Principles And Practice By Theodore S. Rappaport

[3] Math Works: http://www.mathworks.com/

[4] Web Plot Digitizer Tool: http://arohatgi.info/WebPlotDigitizer/

http://www.mathworks.com/

http://arohatgi.info/WebPlotDigitizer/

Mohammed AbuibaidLive & Breathe Wireless