Planet General Model Technical Notes

for

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any previous manuals, guides, specifications data sheets, or other information thatther information that may have been provided or made available t

may have been provided or made available to the user. o the user. This document is providedThis document is provided for informational purposes only, and Mentum S.A. does not

for informational purposes only, and Mentum S.A. does not warrant or guaranteewarrant or guarantee the accuracy, adequacy, quality, validity, completeness or suitability for any

the accuracy, adequacy, quality, validity, completeness or suitability for any  purpose the informat

 purpose the information contained in this dion contained in this document. ocument. Mentum S.A. may upMentum S.A. may update,date, improve, and enhance this document and the products to

improve, and enhance this document and the products to which it relates at anywhich it relates at any time without prior notic

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WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING, WITHOUT WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, THOSE OF MERCHANTABILITY AND FITNESS FOR A LIMITATION, THOSE OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, WITH RESPECT TO THIS DOCUMENT OR THE PARTICULAR PURPOSE, WITH RESPECT TO THIS DOCUMENT OR THE INFORMA

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Mentum, Mentum Planet and Mentum Ellipse are registered trademarks owned by Mentum S.A. Mentum, Mentum Planet and Mentum Ellipse are registered trademarks owned by Mentum S.A. MapInfo Professional is a registered trademark o

MapInfo Professional is a registered trademark of PBf PB MapInfo Corporation. RF-vu is a trademark MapInfo Corporation. RF-vu is a trademark  owned by iBwave.

owned by iBwave. This document may contain other trademarks, traThis document may contain other trademarks, trade names, or service marks de names, or service marks of of  other organizations, each of which is the property of its respective owner.

other organizations, each of which is the property of its respective owner. Last updated June 10, 20

 Notice  Notice

This document contains confidential and proprietary information of Mentum S.A. This document contains confidential and proprietary information of Mentum S.A. and may not be copied, transmitted, stored in a retrieval system, or reproduced in and may not be copied, transmitted, stored in a retrieval system, or reproduced in any format or media, in whole or in part, without the prior written consent of  any format or media, in whole or in part, without the prior written consent of  Mentum S.A.

Mentum S.A. Information contained iInformation contained in this document supersedes than this document supersedes that found int found in any previous manuals, guides, specifications data sheets, or o

any previous manuals, guides, specifications data sheets, or other information thatther information that may have been provided or made available t

may have been provided or made available to the user. o the user. This document is providedThis document is provided for informational purposes only, and Mentum S.A. does not

for informational purposes only, and Mentum S.A. does not warrant or guaranteewarrant or guarantee the accuracy, adequacy, quality, validity, completeness or suitability for any

the accuracy, adequacy, quality, validity, completeness or suitability for any  purpose the informat

 purpose the information contained in this dion contained in this document. ocument. Mentum S.A. may upMentum S.A. may update,date, improve, and enhance this document and the products to

improve, and enhance this document and the products to which it relates at anywhich it relates at any time without prior notic

time without prior notice to the user. e to the user. MENTUM S.A. MAKMENTUM S.A. MAKES NOES NO

WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING, WITHOUT WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, THOSE OF MERCHANTABILITY AND FITNESS FOR A LIMITATION, THOSE OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, WITH RESPECT TO THIS DOCUMENT OR THE PARTICULAR PURPOSE, WITH RESPECT TO THIS DOCUMENT OR THE INFORMA

INFORMATION CTION CONTONTAINED AINED HEREIN.HEREIN.

Trademark Acknowledgement Trademark Acknowledgement

Mentum, Mentum Planet and Mentum Ellipse are registered trademarks owned by Mentum S.A. Mentum, Mentum Planet and Mentum Ellipse are registered trademarks owned by Mentum S.A. MapInfo Professional is a registered trademark o

MapInfo Professional is a registered trademark of PBf PB MapInfo Corporation. RF-vu is a trademark MapInfo Corporation. RF-vu is a trademark  owned by iBwave.

owned by iBwave. This document may contain other trademarks, traThis document may contain other trademarks, trade names, or service marks de names, or service marks of of  other organizations, each of which is the property of its respective owner.

other organizations, each of which is the property of its respective owner. Last updated June 10, 20

Introduction

Introduction

The Planet General Model is a good propagation model to use

The Planet General Model is a good propagation model to use for macro-cellfor macro-cell  planning. It is b

 planning. It is best used for frequencies best used for frequencies between 150 and 200etween 150 and 2000 MHz where0 MHz where the distance between the transmitter and the

the distance between the transmitter and the receiver ranges between 1 andreceiver ranges between 1 and 100 kilometers. Ideally

100 kilometers. Ideally, when using th, when using this model, the base is model, the base station antennastation antenna heights should range between 30 and 1000 meters and the mobile station heights should range between 30 and 1000 meters and the mobile station antenna heights should be between 1 and 10

antenna heights should be between 1 and 10 meters.meters. How the Planet General Model was

How the Planet General Model was originally implemented in Planetoriginally implemented in Planet DMS  DMS 

and how this

and how this model has been implemented in Mentum model has been implemented in Mentum Planet differPlanet differ. On one. On one hand, when Planet

hand, when Planet DMS  DMS  performs predic performs predictions, it calculatetions, it calculates the path loss for s the path loss for 

each pixel or element within the prediction

each pixel or element within the prediction area by calculating a terrainarea by calculating a terrain  profile from the

 profile from the base site to that base site to that element. The pelement. The profile is used by therofile is used by the  propagation model

 propagation model to calculate the pto calculate the path loss to that path loss to that point. Predictions do notoint. Predictions do not include losses or gains due

include losses or gains due to antenna masks. This allows real time maskingto antenna masks. This allows real time masking of antennas each time the prediction is loaded. The height profiles have been of antennas each time the prediction is loaded. The height profiles have been compensated for the effect of the

compensated for the effect of the Earth’Earth’s curvature. A radius s curvature. A radius of 4/3rds of of 4/3rds of thethe Earth’

Earth’s true radius (4/3 x s true radius (4/3 x 6300km = 8400 km) is often used, although this can6300km = 8400 km) is often used, although this can  be changed in the Pl

 be changed in the Planetanet DMS  DMS Model Editor.Model Editor.

On the other hand, when Mentum Planet performs predictions, it calculates a On the other hand, when Mentum Planet performs predictions, it calculates a  prediction for each p

 prediction for each pixel along radialixel along radials in the prediction s in the prediction area. Then, usingarea. Then, using interpolation, Mentum Planet generates predictions in the prediction area on a interpolation, Mentum Planet generates predictions in the prediction area on a  per pixel b

 per pixel basis. This results in basis. This results in better control of tetter control of the calculation tihe calculation time/accuracyme/accuracy ratio; however

ratio; however, for this , for this reason, there may be reason, there may be slight differences betweeslight differences between then the results generated by Planet

results generated by Planet DMS  DMS and those generated and those generated by Mentum Planet. Toby Mentum Planet. To

minimize these differences, you can increase the number of radials used in the minimize these differences, you can increase the number of radials used in the  prediction.

Standard propagation model

The received signal strength at the mobile is given by the following equation.

Where

is the receive power in dBm

is the transmit power (ERP) in dBm. is the constant offset in dB.

is the multiplying factor for log(d).

With the two piece model, both and can be assigned two sets of values. One set is used for d< distance and the other for d> distance, where distance is the distance in meters away from the base site specified in the Model Editor.

is the multiplying factor for log( ). It compensates for gain due to antenna height.

is the multiplying factor for diffraction calculation.

is the Okumura-Hata type of multiplying factor for .

is correction factor for the mobile effective antenna height gain ( ).

d is the distance, in meters, of the receiver from the base site.

is the effective height of base site antenna from ground.

Diffraction is the value calculated for loss due to diffraction over an obstructed path. The value produced is a negative number so a positive multiplication factor, is required.

is the gain in dB for the clutter type at the mobile position in Planet DMS . In Mentum Planet, represents a loss.

is the mobile effective antenna height.

 P  _RX   P _TX   K ₁  K ₂log( )d   K ₃log(  H _{ef f} )  K ₄ Di ff ra ct io n K ₅log(  H _{ef f} )log( )d   K ₆( H _meff )  K _CLUTTER + + + + + + + =  P  _RX   P _TX   K ₁  K ₂  K ₁  K ₂  K ₃  H _{ef f}   K ₄  K ₅ log(  H _{ef f} )log( )d   K ₆  K ₆ H _{ef f}   H _{ef f}   K ₄  K _CLUTTER  K _CLUTTER  H _meff 

Effective antenna heights

Effective antenna height at the transmitter 

The effective antenna height ( ) in meters described in the previous equation may be calculated from any one of the following variables:

■ Base height ■ Spot height ■ Average height ■ Slope

■ Ground Reflection Slope ■ Profile

■ Absolute spot height Base height

Effective antenna height ( ) is set equal to the base site height above ground.

Spot height

Where

is the antenna height above ground at the base site. is the terrain height above sea level at the base site.

is the terrain height above sea level at the mobile site.

Average height

The average height is defined as the height of the base site antenna above the average terrain height, calculated over the total area of the prediction. The effective antenna height ( ) is set equal to average height.

In Mentum Planet, the average height is a user-defined value.

Slope

The effective height of the antenna is calculated using the slope of the terrain over a specified distance up to the antenna. Figure 1 on page 6 displays the

 H _{ef f}   H _{ef f}  If  H _0b> H _0mthen H_{ef f} = H _b+ H _0b –  H _0m If H_0b≤ H _0mthen H_{ef f} = H _b  H _b  H _0b  H _0m  H _{ef f} 

The slope algorithm is

Where

is the ground height at transmitter + antenna height. is the ground height at receiver + mobile height. d is the distance, in meters, of receiver from base site.

K is the slope. This is calculated over a user specified distance ds from the mobile towards the base station using the difference in height over that range.

Figure 1 Slope algorithm for effective antenna height

Ground Reflection Slope

The effective height of the antenna is calculated using the slope of the terrain at the ground reflection point closest to the receiver. The calculation

automatically imposes a limit of 0.8 to 4 times the height of the base station antenna. The values specified for the Minimum Height and Maximum Height have no effect on the calculation if they are not within these limits. If the line of sight between the transmitting and receiving antennas is obstructed, the height of the base station antenna above ground is used.

 H _{ef f} 

=

(

h₁

 – 

h₂

)

+

(

 K

×

d 

)

h₁ h₂ h₁ h₂ Slope K  T  _x  R _x d   H _eff  d  _s

Profile

The profile algorithm calculates an average height along the profile between the transmitter and receiver. can be calculated in three ways:

■ using CCIR recommendations ■ using the Okumura calculations

■ using user-defined start and end points for the profile Using CCIR recommendations

There are three conditions for the distance between the point under  consideration and the antenna:

■ less than 3 km

■  between 3 and 15 km ■ greater than 15 km

(i) Distance to the antenna is less than 3 km

Where

is the antenna height on the mast.

The effective antenna height is the height of the antenna above the ground. An antenna mounted 30 m up on a mast at a ground height of 20 m would confer  a of 50 m on any pixel within 3 km along any profile.

(ii) Distance to the antenna is between 3 km and 15 km

 H _{ef f} 

 H _{ef f}  =  H _transmitter + H  _{g ro un d} 

 H _transmitter 

 H _{ef f} 

Where

is the antenna height on the mast

is the height or DTM height of the base above sea level

average height is given by:

(iii) If distance to antenna is greater than 15 km, the equation for effective antenna height is identical to that in (ii) above. However, average height is now given by:

Okumura calculations for effective antenna height

Effective antenna height is given by the same equation as CCIR (ii) above. Again, the expression for the average height varies with the distance as follows.

(i) The distance to the antenna is between 3 km and 15 km. average height is given by

(ii) The distance to the antenna is greater than 15 km.

For all points over 15 km, the average height between 3 km and 15 km is used.

average height is therefore

User-defined start/end points

You can define the start and end points of the profile, in kilometers from the antenna base.

 H _transmitter   H  _{gr ou nd} 

sum of pixel heights along profile from 3km to distant point number of pixels along this profile

---sum of pixel hights along profile from 3km to 15km number of pixels along this profile

---sum of pixel heights along profile from base of antenna to po number of pixels along this point

---sum of pixel heights along profile from 3 km to 15 km number of pixels along this profile

--- Absolute spot height

This algorithm uses the equation:

The absolute value of is used.

Effective antenna height is not limited to H _b as the mobile height ( ) goes above the base height ( ).

Effective antenna height at the mobile

The standard propagation model uses the mobile effective antenna height together with a linear correction factor ( ).

The following figure shows how these heights are calculated.

Figure 2 Effective antenna height at the mobile

Obstruction loss equations

Calculating obstruction loss

The prediction routine creates a “height path profile” between the base site and mobile and calculates the obstruction position as shown in Figure 3 (in this case only one obstruction is shown). A straight line between base site and mobile is shown and the height of the obstruction above this line, is

calculated. The obstruction position, is also recorded. From these variables, , the argument of the Fresnel integral is calculated.

 H _{ef f} 

=

 H _b

+

 H _0b

 – 

 H _0m  H _0b –  H _0m  H _0m  H _0b  K ₆  H _meff  h_0m h m + ( ) – h_0b = h_m h_0m h_0b base mobile c_i d _i v_i v_i c_i

2

d  d _i

λ

(

d

 – 

d _i

)

---=

Where λ is the wavelength and d is the terrain slope distance. A value of  less than -0.8 indicates sufficient clearance for the Fresnel zone is obtained over the whole path. The path loss equation for line of sight is used. Where a loss is indicated, the Fresnel integral is used.

This is an integral and stored as a lookup table for values of - 0.8 ≤ < 2.0 and the loss is calculated from.

Where the value of v_i is greater than or equal to 2.0, an approximation is used.

For multiple diffraction edges, this knife edge diffraction calculation is applied to each edge in turn and the result in dB is summed. The following figure shows terrain with two obstructions, edge A and B. The variables , andd are used in the diffraction equation as before.

Figure 3 Obstruction Loss, Edge A

For edge B, the variables , and are similarly used, as shown in the following figure.

Figure 4 Obstruction Loss, Edge B

v_i  E   E 

---

₀

1

+

 j

2

---

e(  –  j( π ⁄ 2))v2dv v_i ∞

∫

×

=

v_i  P  _{LO SS} 

20

 E   E 

---

₀

log

×

=

 E   E 

---

₀

0.225

v_i

---=

c_i d _i d d_i Mobile Base Site c_i Edge B Edge A c_b d _am d _ab

Path loss lookup table

The following table is the look-up table used in calculating the path losses, in dB. For intermediate values, the loss is linearly interpolated.

Table 1.1 Path loss

vi Ploss -0.8 0.0 -0.7 -0.46 -0.6 -1.13 -0.5 -1.86 -0.4 -2.64 -0.3 -3.45 -0.2 -4.29 -0.1 -5.15 0.0 -6.02 0.1 -6.90 0.2 -7.74 0.3 -8.59 0.4 -9.42 0.5 -10.23 0.6 -11.03 0.7 -11.77 0.8 -12.50 0.9 -13.15 Mobile Base Site Edge B Edge A c_b d_ab d_am

Troposcatter model

The troposcatter model is generally used in the Planet DMS Microwave tool.

It is set when the Use the Troposcatter Model check box in the Planet DMS 

Model Editor is selected and the distance between the transmitter and the  point at which loss is calculated is greater than the transition distance, .

Where dt = dh, when dh > 90.3953

Otherwise,dt = dhata Where

and

is the transhorizon distance in km. is the effective earth radius in km.

and PCS and MW Receiver antenna heights above average

terrain.This applies if the height is greater than 5m, otherwise it is set at 5.

Where

d _hata is the Hata Merge Distance in km.

1.0 -13.85 1.1 -14.52 1.2 -15.09 1.3 -15.70 1.4 -16.25 1.5 -16.77 1.6 -17.27 1.7 -17.79 1.8 -18.20 1.9 -18.63 2.0 -18.94

Table 1.1 Path loss (continued)

vi Ploss d _t  d _h

2

a0

1000

---

(

h _{pc s}

+

h_mw

)

=

d _h a₀ h _{pc s} h_mw d _hata

=

 –

115

+

105

log

d _h

The hourly median troposcatter loss 50% of the time is given by

Where

 L₅₀is the hourly median transmission loss 50% of the time (dB).  f is the frequency (MHz).

d is the path length (km).

θ (d-d_h)/8.5 (milliradians) - d _h is defined above.

and

Where

 H equals θd/4000.

h equals 10-6θ2a₀/8 km.

a₀ is the effective earth radius in km.

 M is the meteorological structure parameter; this value depends on the climate

type which you select in the Model Editor. The values for each climate type are given in the table below.

γ is the atmospheric structure parameters; this value depends on the climate type which you select in the Model Editor. The values for each climate type are given in the following table.

Climate 1 2 3 4 6 7a 7b

M (dB) 39.60 29.73 19.30 38.50 29.73 33.20 26.00

γ(km-1) 0.33 0.27 0.32 0.27 0.27 0.27 0.27

 L₅₀

=

 M 

+

30

log

( )

 f 

+

10

log

( )

d 

+

30

log

( )

θ

+

 N H h

(

,

)

The climate types are:

For confidence levels q above 50%, the loss becomes: Where

andc_q is taken from the following table:

The calculated loss is compared with the Free Space Loss along the path; if  the free space loss is greater, this is used rather than the troposcatter loss.

Microwave application

When the troposcatter model is used in a microwave application, for a

confidence level q above 50%, the troposcatter loss is calculated as follows:

Where

equals

is the antenna gain of transmitter in dBi. is the antenna gain of the receiver in dBi.

Type 1 Equatorial

Type 2 Continental sub-tropical Type 3 Maritime sub-tropical

Type 4 Desert

Type 6 Continental Temperate

Type 7a Maritime Temperate, over land Type 7b Maritime Temperate, over sea

q 50 80 90 99 99.9 99.99 0 0.67 1 1.82 2.41 2.90  L_q

=

 L₅₀

+

c_q L₉₀  L₉₀

=

 –

2.2

 – 

(

8.1 2.3 10

 – 

×

 – 4 f 

)

e – 0.137h c_q  L_q

=

 L₅₀

+

 L_c

 – 

c_q L₉₀  L_c

0.07

×

exp

[

0.055

×

(

G_T 

+

G _R

)

]

G G _R

Clutter effects

Clutter losses/gains

The loss/gain (referred to from now on as a loss for simplicity) due to clutter 

is calculated as follows:

For x=0 to n

Clutter Loss = K*Fn(K _clutter x)

Where

 x=0 is the pixel at the mobile.

 x=n is the pixel that is L meters away.

 K is a scaling coefficient (usually set to 1.0).

 K _clut ter  x is the clutter loss from the clutter at point x.  Fn() is the function for weighting the clutter losses.

Currently the functions supplied are:

■ Rectangular  ■ Triangular  ■ Logarithmic ■ Exponential

With the rectangular function, each clutter loss has the same weighting. With the others, clutter loss at the receiver has the highest effect. Clutter loss at n

has no effect. The triangular function gives a linear decay. Exponential decays quickest near the mobile and logarithmic decays furthest from the mobile.

L

Clutter losses are considered over a distance L. L is in meters and is definable.

Clutter heights

Clutter heights can be added to the terrain height during predictions to

calculate the obstructions loss more accurately. The clutter height is not added to the terrain height at the transmitter. Clutter heights are never added at the  base station. The clutter separation factor is used to separate the mobile from

the surrounding clutter; that is, to prevent the mobile being swamped by the clutter as a result of high diffraction losses.

This is achieved as follows:

Let the clutter separation be b, the mobile be at point Rx and the point on the

 profile b meters from Rx be Rb:

■ Mentum Planet will find the highest clutter height along the

 profile between Rx and Rb. Let this be h_max .

■ Mentum Planet will not add clutter heights to any points between

 Rx and Rb. The clutter height added at Rb will be h_max .

■ For the remainder of the profile, clutter heights will be added to

terrain heights normally.

So if a transmitter is on top of a building, the antenna height must be set to the true height of the antenna plus the building height.

If a clutter category is to be assigned a height then it must also be assigned a mobile-to-clutter edge separation distance as well:

Figure 5 Clutter heights

This distance is used to adjust local clutter heights for use in the diffraction calculations. If this value is left at 0.0 the resultant very high diffraction causes “wild” losses.

h_max Rx b b Physical h_max Rx Modelled Rb Rb

Correction factors to Okumura and NTT

You can apply correction factors to Okumura/NTT models and to general models.

Effective base station antenna height correction factor (Ht) This is the effective base station antenna height correction factor:

Ht = A(log₁₀h_te)2+ B(log₁₀h_te) + C

Where

h_te is the effective base station antenna height. Calculate this using the

Okumura recommendations.

 A,B,C are the coefficients dependent on d , see below.

The table below shows coefficients for the effective height of base station antenna correction factor at several distances.

Linear interpolation is used between these values. Rolling hilly correction factor (K_h)

This is the rolling hilly correction factor:

K _h= -5.180(log₁₀

Δ

h)2+3.538(log₁₀

Δ

h) +3.105

Where

Δ

h is the difference in 10% and 90% heights over a distance X along the

 profile from the receiver to the transmitter.

d (km) A B C 1 0.5131 11.68 -23.32 3 0.2433 14.42 -27.31 5 0.3690 15.60 -29.94 10 0.5457 17.75 -34.66 20 2.568 11.89 -30.61 40 4.289 7.019 -27.66 70 4.225 4.830 -23.23

Figure 6 Rolling hilly correction factor  Where

Δ

h> 20m and number of “peaks” greater than or equal to 3.

You can choose to set the distance X in 3 ways:

1 Use Okumura recommendations, up to 15km from transmitter.

2 Use CCIR recommendation, 10km to 50km from transmitter in direction

of receiver.

3 Define your own start and end points.

Rolling hilly correction fine factor (K_hf ) This is the rolling hilly correction fine factor:

K _hf = -1.4191(log₁₀

Δ

h)2 + 14.0544(log₁₀

Δ

h) -10.727

This correction factor is only applied at the top of a hill or at the bottom of a valley.

Where

Δ

h is the difference in 10% and 90% heights over a distance X along the

 profile from the receiver to the transmitter.

Then, at a position of undulation (peak or valley):

 K _{hf (position of undulation/m)} = K _hf  /( Δh/2) whereΔh > 10m  K _{hf (position of undulation/m)} = 0.0 where Δh <= 10m

Then

 K _{hf (position of undulation)}= K _{hf (position of undulation/m)}x (( Δh/2)-h) Δh

10%

90%

h is the height at position of undulation.

The value of  K _{hf (position of undulation)}is the value that should be applied to the

 propagation equation.

Inclination correction factor (K _sp)

This is only calculated if there is line-of-sight between the base site and the mobile. It calculates the angle of inclination over a distance of 5km from receive point to transmitter as follows:

Figure 7 Inclination Correction Factor 

The equation of the line is given as h_a = ad +b (this line is obtained using a

least squares fit):

θm = arctan(a) x 17.4532 (in mrad)

Then, if 3 ≤ |θ_m| ≤ 20mrad :  K  _sp = Aθ_m2 + Bθ_m + C   A, B, C are dependent on d:

The table below shows coefficients for inclination correction factor at several distances:

For other ranges of d , linear interpolation is used.

d (km) A B C >60 -0.009411 0.7620 0.22 =30 -0.013400 0.6313 -0.63 <10 -0.002394 0.2057 0.12 h =ad +b 5km hi di

Sea/lake edge correction factor (K_se) If there is water at the side of the mobile:

 K  _se = -0.001191

β

2 +0.2620

β

+ 0.27 for d ≥ Š60km

K _se = K _se30 + C_oe(d-30)for 30km<d<60km C_oe =(K _se60-K _se30)/(60-30)

 K  _se = -0.000789

β

2+0.1868

β

+0.06 for d ≤ 30km

If there is water at the side of the base station:

 K  _se =0.000454

β

2 +0.1143

β

+0.27for d ≥ 60km

K _se = K _se30 + C_oe(d-30)for 30km<d<60km C_oe =(K _se60-K _se30)/(60-30)

 K  _se =0.0005795

β

2 +0.06893

β

- 0.09for d ≤ 30km

where

β

= d  _sr  /d as a percentage.

Figure 8 Sea/lake edge correction factor (Kse)

Suburban area correction factor (K _sub) The correction factor for suburban areas is:

K _sub = 2 (log₁₀(f _c/28))2

Where

 K  _sub is the correction value (dB).  f _c is the frequency in MHz.

If  L _p is the standard equation for the loss in an urban area in dB then for the

suburban area: L _ps= L _p - K _sub

Where

 L _ps is the loss in a suburban area (dB). d

dsr  Base site

Open area correction factor (K_open) The correction factor for open areas is:

K _open= 4.78 (log₁₀ f _c)2 - 18.33 log₁₀ f _c + 40.94

Where

 K _open is the correction value (dB).  f _c is the frequency in MHz.

If  L _p is the standard equation for the loss in an urban area in dB then for the

open area:

L _po= L _p - K _open

Where

 L _pois the loss in an open area (dB).

Knife edge correction factor (K_im) The correction factor for knife edge is: K _im = 0.07÷h (Ad₂4 + Bd₂3+ Cd₂2 + Dd₂)

Where

 K _im is the correction value (dB). h is the height of knife edge.

d ₂ is the distance from knife edge to mobile (km). d ₁is the distance from base station to knife edge (km).

Figure 9 Knife edge correction factor (Kim)

d₁ d₂

Tx _Rx

 A, B, C & D are dependant on d ₁:

Multiple knife edge correction factor (K _mke)

The multiple knife edge correction factor is given by the term,

 K _mke = -0.031072512

∑

 H _i +1.39870768

where H _iare knife edges:

Figure 10 Multiple knife edge correction factor (K_mke)

Building density correction factor (S)

The building density factor is defined as

α

, such that 0% <

α

< 40%.

Then

S= 20 (

α ≤

1%)

S= 20 -3.74(log₁₀

α

) - 9.75(log₁₀

α

)2(1%<

α

<5%) S= 26 -19.0(log10

α

)(5

%≤α

)

These equations are valid for 2km< d < 40km.

Each clutter type has its own, user-definable, value for building density.

d1 (km) A B C D >60 0.08492 -1.677 11.47 -30.41 =30 0.06259 -1.280 9.184 -25.19 <15 0.04980 -1.065 8.102 -23.33 Tx  Rx  Hi 

Mobile antenna height correction factor (H_r )

The mobile antenna height correction factor, H_r , is valid for all Okumura frequencies and clutter types.

H_r = 22.92(log₁₀h_re)3 - 10.27(log10h_re)2 + 10.16(log₁₀h_re) -1.9

Where

h_re is the mobile antenna height (m).

Tuning the Planet General model using AMT

The components of the Planet General model can be optimized using the Automatic Model Tuner (AMT) tool.

For detailed instructions on tuning the Planet General model using AMT, see Chapter 4, “Working with Propagation Models”, in the Mentum Planet User  Guide.

Technical overview

AMT optimizes the clutter absorption loss and K1 to K5 factors. For more information on the path loss equation for Planet General model, see “Standard  propagation model” on page 4.

To determine the K factors that can be automatically tuned, AMT performs correlation and cross-correlation tests between the predicted path loss and the

, , and model components.

The correlation factor calculations determine the model components that are similar with the actual path loss. A high correlation value (1) between a model component and path loss implies high similarity, indicating that the

component can model path loss well.

For example, if the correlation factor between path loss and diffraction is small (close to 0), using diffraction loss will not improve the root mean square (RMS) error of the model significantly. If you optimize the diffraction loss factor (K4), the RMS error will not be reduced by a significant amount and the optimized value for K4 might be invalid (less than 0).

dm

Correlation and cross-correlation thresholds

AMT uses a number of conditions based on the correlation calculations and correlation thresholds to decide whether a condition should be optimized or  not. These conditions are outlined in Table 1.2 and Table 1.3.

Default values for model parameters

The following tables describe the default values for each model parameter in the Planet Automatic Model Tuner dialog box.

Table 1.2 Correlation tests Correlation Tests Measurement Data Model Component Correlation Factor  Correlation Threshold (pT) Path loss p2 0.0

Pathloss p3 p3T (AMT default

is 0.2)

Pathloss p4 p4T (AMT default

is 0.2)

Table 1.3 Cross-correlation tests Cross-correlation Tests Measurement Data Model Component Correlation Factor  Correlation Threshold p24 p24T (AMT default is 0.9) p35 p35T (AMT default is 0.9) d  ( ) log h_{ef f}  ( ) log  –  d _loss d _loss log( )d   H _{ef f}  ( )

K1

K2

K3

K4

Options Default value

Optimize Calculated by optimization Hata urban For 150 to 1500 MHz:

For 1500 to 2000 MHz:

Hata suburban For 150 to 2000 MHz:

Hata rural For 150 to 2000 MHz:

Free space

User defined Value set by user  

Options Default value

Optimize Calculated by optimization

Hata value -44.9

Free space -20.0

User defined Value set by user  

Options Default value

Optimize Calculated by optimization

Hata value -5.83

Free space 0

User defined Value set by user  

Options Default value

Optimize Calculated by optimization 44.9 3×

( ) – [ 69.55 26.16+ log( ) f ]

44.9 3×

( ) – [ 46.33 33.91+ log( ) f ]

 K 1

 Ha ta Ur ban 2[ log(  f  ⁄ 28)]

2

5.4

+ +

 K 1

 Ha ta Ur ban 4.78[ log( ) f ]

2

18.33log( ) f  +40.94  – 

+ 60 32.44 20 –   –  log( ) f 

K5

Clutter Offsets

Requirements for optimization

Table 1.4 describes the optimization requirements for each factor.

User defined Value set by user  

Hata value 0

Free space 0

Options Default value

Optimize Calculated by optimization

Hata value 6.55

Free space 0

User defined Value set by user  

Options Default value

Optimize Calculated by optimization

Zero 0

User defined Value set by user  

Table 1.4 Optimization requirements for factors

K Factor Requirements for Optimization

K1 Can always be optimized

K2 Can always be optimized

K3 _{If and}

K4 _{If and and}

K5 _{If and and}

Clutter offsets Can always be optimized

Options Default value

 p3> p3T   p3 0.01>

 p4> p4T   p24< p24T   p4 0.01>  p3> p3T   p35< p35T   p3 0.01>

To create an AMT template

To tune a model with AMT using the Standard method (see “Developing an optimized Planet General model” on page 29), you must first create a custom template based on the Planet General model. An AMT model template

contains default settings intended for use with AMT.

1 In Mentum Planet, choose Edit ➤Propagation Models. The Create/Edit Propagation Model dialog box opens.

2 Choose Create New Propagation Model and, from the associated list, choose Planet General Model, and click OK .

The Propagation Model Editor opens.

3 Click the Settings tab and, in the Name box, define a name for the new model.

4 In the Receiver Height section, choose Global.

5 Click the General tab.

6 In the Model section, for the Type option, choose 1 Piece.

7 In the K Factors section, do all of the following:

■ From the Intercept, K1 (near) list, chooseUser Defined, and

type -120 in the box.

■ From the Slope, K2 (near) list, choose Hata Value.

■ From the Effective Antenna Height Gain, K3 list, choose Free

Space.

■ From the Diffraction Factor, K4 list, chooseUser Defined, and

type 1 in the box.

■ From the Log(Heff) * Log(d) Factor, K5 list, choose Free

Space.

■ From the Mobile Antenna Height Factor, K6 list, choose Free

Space.

8 In the Knife Edge section, in the Merging Distance box, type 100.

9 Click the Path Clutter tab and clear the Enable Path Clutter check box.

10 Click the Troposcatter Effect tab and clear the Enable Troposcatter Model check box.

12 Click the Effective Antenna Height tab, and from the Type list, choose Spot Height.

13 Edit any of the other settings as required. 14 Click OK.

The propagation model is saved in the Models folder of your project. Developing an optimized Planet General model

This section describes how to create an optimized Planet General model using the Standard method. To use the standard method, you should have a good understanding of Mentum Planet and be well versed in how to tune a model.

To develop an optimized PGM using the Standard method

1 In the Project Explorer, in the Operational Data category, right-click a survey and chooseModel Tuning.

2 In the Model Tuning dialog box, type a name for the tuned model in the New Model Name box.

3 From the Model to Tune list, choose an AMT template file.

For more information on creating a template file, see “To create an AMT template” on page 28.

4 From the Model Tuner list, choose Planet AMT Version 1.5.

5 In the Model Tuning dialog box, click Edit Tuner. The Planet Automatic Model Tuner dialog box opens.

If you have little or no knowledge of model tuning , you can use the Smart method to tune your model. For more information, see “Tuning the Planet General model using AMT”, in Chapter 4, “Working with

6 Do all of the following:

■ From the K1, K2, andK4 lists, choose Optimize.

■ From the K3 and K5 lists, choose Hata value, and set Clutter

Offsets to 0.

■ Click OK to close the dialog box, and then click OK to begin the

model tuning process.

■ Examine the mean error for each site. Note the sites with large

mean errors and RMS errors (assuming that there is a minimum of 1000 points for each site). If not enough points are available for the site, the mean error estimates will be inaccurate.

7 If K4 cannot be optimized, or if the optimized value of K4 is less than 0.2, do the following in the Planet Automatic Model Tuner dialog box:

■ Type 0.5 in the K4 box

■ Choose Optimize for K1 andK2 again

■ Click OK to close the dialog box, and then click OK to begin the

model tuning process.

■ Examine the mean error for each site.

8 If you want to further tune the model that you tuned in Step 7, do the

following in the Planet Automatic Model Tuner dialog box:

■ From the K1, K2, andK4 lists, type values that you obtained in

Step 7.

■ From the K3 and K5 lists, choose Hata value. ■ From the Clutter Offsets list, choose Optimize.

■ Click OK to close the dialog box, and then click OK to begin the

model tuning process.

■ Examine the mean error for each site. Clutter offsets with values

less than 90 to 95% are considered to be unreliable estimates. Unless you think that these values are unreasonable, unreliable clutter values should not be used; instead, you should set their  values to 0.

9 (Optional) If you want to further optimize the Planet General Model, repeat the steps described in Step 8, and do the following in the Planet General Model Parameters dialog box

■ Click the Path Clutter tab.

■ On the Path Clutter tab, enable the Enable Path Clutter check 

 box. Typical path clutter distances are 500 m to 1000 m.

■ Click OK to close the dialog box, and then click OK to begin the

model tuning process.

■ See if there are any improvements not only in the RMS error but

with the predictions.

10 Identify the sites that have a significant absolute mean error (greater than

5 dB) and see if these sites can be classified in a different environment. Develop a new model for sites that have large mean errors.

Obtaining a model similar to Hata COST-231

The Hata COST-231 model for 9000 MHz and 1800 MHz has been obtained from measurements in Europe. The model is composed of the Hata Urban model plus a correction factor to account for different environments.

The Hata COST 231 model can be represented by the following equation:

or 

Where

is the path loss (in dB)

is the height of the base station above ground level (in meters) is the frequency (in MHz)

is the distance between the base station antenna and the mobile receiver  with a height of 1.5 meters

The Clutter Absorption Loss is the additional loss in dB with respect to the Hata Urban path loss. The valid range of the parameters is:

 L _p ( k f ( ) – 13.82log10h_b) ( 44.9 6.55 –  log10h_b) 10 dkm( )+Clutter Absorption Loss

( )

log

+ =

 L _p = L _{Ha ta} +Clutter Absorption Loss

 L _p h_b

Where

represents 30m to 200m represents 1 km to 20 km represents 1.5 m

You can optimize the propagation model by setting factors K1 to K5 to the Hata values (note that K4 is equal to 0 for the Hata model) and obtain the Clutter Absorption Loss using AMT.

Using the Free Space factor 

Knife Edge diffraction theory models propagation loss as

. This produces reasonable results in rural areas where terrain is the main source of obstructions. You can set factors K1 to K2 to the Free Space values and optimize the diffraction factor, K4. You can obtain better results when you set K2 to the Free Space value (-20) and set K1 and K4 to be optimized.

Another option is to set K2 to -20, K4 to 1.0 and to optimize K1 only (and the Clutter Offsets factor if a variety of clutter classes exists in that area). Good models can be obtained using this method in areas where shadowing is

dominated by terrain and not by buildings (i.e., highway sites in rural areas). Even if the RMS error is large (greater than 9 dB), the prediction will most likely be reasonable.

Using Okumura correction factors

An Okumura-Hata propagation model is derived empirically for areas with quasi-smooth terrain (i.e., with no significant terrain variations or hills). The effects of the terrain are accounted for using specified Okumura correction factors. The height parameter (hb) in the Hata-Okumura model corresponds to the height of the base station.

When the Okumura correction factors are used, it is appropriate to use the Base Height algorithm when determining the Effective Antenna Height. Other  algorithms that can be used and produce reasonable model factors are the Spot Height, Absolute Spot Height, and Profile algorithms. When you use the

k f ( ) = 69.55 26.16+ log10( ) f for f 150 MHz to 1500 MHz=

k f ( ) = 46.3 33.9 26.16+ ( )log10( ) f for f 1500 MHz to 2000 MHz=

h_b dkm

hm

Slope algorithm, it is recommended that you set K5 to 0. It is also

recommended that Okumura correction factors are not used with the Slope algorithm. These recommendations are based on analyses of real

measurement data.

Effects of each model component

You can observe the effect of each component in the model and check if an acceptable RMS error can be obtained from a simpler model using the following steps:

1 In the Planet Automatic Model Tuner dialog box, do the following:

■ Choose Optimize from the K1 and K2 lists. ■ Choose Hata from the K3 and K5 lists. ■ Type 0.5 in the K4 box.

■ Type 0 in the Clutter Offsets box.

■ Click OK to close the dialog box, and then click OK to begin the

tuning process.

■ See if there is an improvement in the RMS error.

2 If there was an improvement in the RMS error for K1 and K2, do the

following in the Planet Automatic Model Tuner dialog box:

■ Type the values that you obtained for K1 and K2 in Step 1 in the

respective boxes.

■ Choose Optimize from the K4 list. ■ Choose Hata from the K3 and K5 lists. ■ Type 0 in the Clutter Offsets box.

■ Click OK to close the dialog box, and then click OK to begin the

tuning process.

3 If there was an improvement in the RMS error, do the following in the

Planet Automatic Model Tuner dialog box:

■ Type the values that you obtained for K1, K2, and K4 in Step 2

in the respective boxes.

■ Choose Optimize from the K3 list. ■ Choose Hata from the K5 list. ■ Type 0 in the Clutter Offsets box.

■ Click OK to close the dialog box, and then click OK to begin the

tuning process.

■ See if there is an improvement in the RMS error.

4 If there was an improvement in the RMS error, do the following in the

Planet Automatic Model Tuner dialog box:

■ Type the values that you obtained for K1, K2, K4, and K3 in

Step 3 in the respective boxes.

■ Choose Optimize from the K5 list. ■ Type 0 in the Clutter Offsets box.

■ Click OK to close the dialog box, and then click OK to begin the

tuning process.

■ See if there is an improvement in the RMS error.

5 In the Planet General Model Parameters dialog box, do the following:

■ Click the Effective Antenna Height tab.

■ On the Effective Antenna Height tab, choose an algorithm from

the Type list.

■ Click OK to close the dialog box, and then click OK to begin the

tuning process.

■ Repeat these steps to see which algorithm displays a higher 

correlation and produces a lower RMS error or lower maximum error.

6 If there was an improvement in the RMS error, do the following in the

Planet General Model Automatic Model Tuner dialog box:

■ Type the values that you obtained for K1, K2, K3, K4, and K5 in

Step 4 in the respective boxes.

■ Choose Optimize from the Clutter Offsets list.

■ Click OK to close the dialog box, and then click OK to begin the