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Planet 6.2

Planet General Model Technical Note

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Last updated January 17, 2017

Planet General ModelTechnical Note

IntroductionThe Planet General Model is a good propagation model to use for macro-cell planning. It is best used for frequencies between 150 and 2000 MHz where the distance between the transmitter and the receiver ranges between 1 and 100 kilometers. Ideally, when using this model, the base station antenna heights should range between 30 and 1000 meters and the mobile station antenna heights should be between 1 and 10 meters.How the Planet General Model was originally implemented in Planet DMS and how this model has been implemented in Mentum Planet differ. On one hand, when Planet DMS performs predictions, it calculates the path loss for each pixel or element within the prediction area by calculating a terrain profile from the base site to that element. The profile is used by the propagation model to calculate the path loss to that point. Predictions do not include losses or gains due to antenna masks. This allows real time masking of antennas each time the prediction is loaded. The height profiles have been compensated for the effect of the Earth’s curvature. A radius of 4/3rds of the Earth’s true radius (4/3 x 6300km = 8400 km) is often used, although this can be changed in the Planet DMS Model Editor.On the other hand, when Mentum Planet performs predictions, it calculates a prediction for each pixel along radials in the prediction area. Then, using interpolation, Mentum Planet generates predictions in the prediction area on a per pixel basis. This results in better control of the calculation time/accuracy ratio; however, for this reason, there may be slight differences between the results generated by Planet DMS and those generated by Mentum Planet. To minimize these differences, you can increase the number of radials used in the prediction.

3

Technical Note

Standard propagation modelThe 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.

PRX PTX K1 K2 d( )log K3 Heff( )log K4Diffraction K5 Heff( ) d( )loglogK6 Hmeff )( KCLUTTER

+ + + + ++ +

=

PRX

PTX

K1

K2

K1 K2

K3 Heff

K4

K5 Heff( ) d( )loglog

K6 K6Heff

Heff

K4

KCLUTTERKCLUTTER

Hmeff

4


Effective antenna heights

Effective antenna height at the transmitterThe 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 heightEffective 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 heightThe 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.

SlopeThe 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 slope algorithm.

Heff

Heff

If H0b H0m> then Heff Hb H0b H0m–+=

If H0b H0m≤ then Heff Hb=

Hb

H0b

H0m

Heff

5

Technical Note

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 SlopeThe 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.

Heff h1 h2–( ) K d×( )+=

h1

h2

h1

h2

Slope K

Tx

Rx

d

Heff

ds

6


ProfileThe 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 recommendationsThere 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

Heff

Heff Htransmitter Hground+=

Htransmitter

Heff

Heff Htransmitter Hground averageheight–+=

7

Technical Note

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 heightEffective 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.

Htransmitter

Hground

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

------------------------------------------------------------------------------------------------------------------------------------------------

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

-----------------------------------------------------------------------------------------------------------------------------

sum of pixel heights along profile from base of antenna to ponumber of pixels along this point

--------------------------------------------------------------------------------------------------------------------------------------------------

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

----------------------------------------------------------------------------------------------------------------------------------

8


Absolute spot heightThis algorithm uses the equation:The absolute value of is used.Effective antenna height is not limited to Hb as the mobile height ( ) goes above the base height ( ).

Effective antenna height at the mobileThe 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 lossThe 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.

Heff Hb H0b H0m–+=H0b H0m–

H0mH0b

K6

Hmeff h0m hm+( ) h0b–=

hm

h0m

h0b

basemobile

cidi

vi

vi ci2d

diλ d di–( )--------------------------=

9

Technical Note

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 vi 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 , and d 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

vi

EE0------

1 j+2

----------- e j π 2⁄( )–( )v2dv

vi

∞

∫×=

vi

PLOSS 20 EE0------log×=

EE0------

0.225vi

-------------=

ci di

d

di

MobileBase Site

ciEdge B

Edge A

cb dam dab

10


Path loss lookup tableThe 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

MobileBase Site

Edge B

Edge A

cb

dab

dam

11

Technical Note

Troposcatter modelThe 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 > 90.3953Otherwise, dt = dhataWhere

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.

Wheredhata 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

dt

dh 2a0

1000------------ hpcs hmw+( )=

dh

a0

hpcs hmw

dhata 115– 105 dhlog+=

12


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

WhereL50 is the hourly median transmission loss 50% of the time (dB).f is the frequency (MHz).d is the path length (km).θ (d-dh)/8.5 (milliradians) - dh is defined above.and

WhereH 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 f( )log 10 d( )log 30 θ( )log N H h,( )+ + + +=

N H h,( ) 20 5 γH+( )log 4.343γh+=

13

Technical Note

The climate types are:

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

Where

and cq 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 applicationWhen 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

Lq L50 cqL90+=

L90 2.2– 8.1 2.3 10 4– f×–( )e 0.137h––=

cq

Lq L50 Lc cqL90–+=

Lc 0.07 0.055 GT GR+( )×[ ]exp×

GT

GR

14


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 nClutter Loss = K*Fn(Kclutterx) Wherex=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).

Kclutterx 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.

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

Receiver Base Station

15

Technical Note

Clutter heightsClutter 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 hmax.

■ Mentum Planet will not add clutter heights to any points between Rx and Rb. The clutter height added at Rb will be hmax.

■ 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:

16


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.

hmax

Rx b

b

Physical

hmax

Rx

Modelled

Rb

Rb

17

Technical Note

Correction factors to Okumura and NTTYou 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(log10hte)2 + B(log10hte) + CWherehte 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 (Kh)This is the rolling hilly correction factor:

Kh = -5.180(log10Δh)2 +3.538(log10Δh) +3.105

WhereΔh 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

18


Figure 6 Rolling hilly correction factor

WhereΔh> 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 (Khf)This is the rolling hilly correction fine factor:Khf = -1.4191(log10Δh)2 + 14.0544(log10Δh) -10.727This correction factor is only applied at the top of a hill or at the bottom of a valley.WhereΔh 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):Khf (position of undulation/m) = Khf/(Δh/2) where Δh > 10mKhf (position of undulation/m) = 0.0 where Δh <= 10mThenKhf (position of undulation) = Khf (position of undulation/m) x ((Δh/2)-h)Where

Δh

10%

90%

X

19

Technical Note

h is the height at position of undulation.The value of Khf (position of undulation) is the value that should be applied to the propagation equation.

Inclination correction factor (Ksp)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 ha = ad +b (this line is obtained using a least squares fit):θm = arctan(a) x 17.4532 (in mrad)Then, if 3 ≤ |θm| ≤ 20 mrad:Ksp = Aθm

2 + Bθm + CA, 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

20


Sea/lake edge correction factor (Kse)If there is water at the side of the mobile:Kse = -0.001191β2 +0.2620β + 0.27 for d ≥ Š60kmKse = Kse30 + Coe(d-30)for 30km<d<60kmCoe =(Kse60-Kse30)/(60-30)Kse = -0.000789β2 + 0.1868β +0.06for d ≤ 30kmIf there is water at the side of the base station:Kse = 0.000454β2 +0.1143β +0.27for d ≥ 60kmKse = Kse30 + Coe(d-30)for 30km<d<60kmCoe =(Kse60-Kse30)/(60-30)Kse = 0.0005795β2 + 0.06893β - 0.09for d ≤ 30kmwhere β= dsr/d as a percentage.

Figure 8 Sea/lake edge correction factor (Kse)

Suburban area correction factor (Ksub)The correction factor for suburban areas is:Ksub = 2 (log10 (fc/28)) +5.42

WhereKsub is the correction value (dB).fc is the frequency in MHz.If Lp is the standard equation for the loss in an urban area in dB then for the suburban area:Lps = Lp - KsubWhereLps is the loss in a suburban area (dB).

ddsr

Base site

Mobile

21

Technical Note

Open area correction factor (Kopen)The correction factor for open areas is:Kopen = 4.78 (log10 fc)2 - 18.33 log10 fc + 40.94WhereKopen is the correction value (dB).fc is the frequency in MHz.If Lp is the standard equation for the loss in an urban area in dB then for the open area:Lpo = Lp - KopenWhereLpo is the loss in an open area (dB).

Knife edge correction factor (Kim)The correction factor for knife edge is:Kim = 0.07÷h (Ad2

4 + Bd23 + Cd2

2 + Dd2) WhereKim is the correction value (dB).h is the height of knife edge.d2 is the distance from knife edge to mobile (km).d1is the distance from base station to knife edge (km).

Figure 9 Knife edge correction factor (Kim)

d1 d2

Tx Rx

height of knife edge

22


A, B, C & D are dependant on d1:

Multiple knife edge correction factor (Kmke)The multiple knife edge correction factor is given by the term,Kmke = -0.031072512∑Hi +1.39870768where Hi are knife edges:

Figure 10 Multiple knife edge correction factor (Kmke)

Building density correction factor (S)The building density factor is defined as α, such that 0% < α < 40%.ThenS= 20 (α ≤ 1%)S= 20 -3.74(log10α) - 9.75(log10α)2(1%<α<5%)S= 26 -19.0(log10α)(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

23

Technical Note

Mobile antenna height correction factor (Hr)The mobile antenna height correction factor, Hr, is valid for all Okumura frequencies and clutter types.Hr = 22.92(log10hre)3 - 10.27(log10hre)2 + 10.16(log10hre) -1.9Wherehre is the mobile antenna height (m).

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

Technical overviewAMT 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).

dmlog Dloss Hefflog

24


Correlation and cross-correlation thresholdsAMT 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 parametersThe 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

Path loss p3 p3T (AMT default is 0.2)

Path loss 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

heff( )log–

dloss

dloss d( )log

Heff( )log d( ) heff( )loglog

25

Technical Note

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



Hata value -44.9

Free space -20.0




Hata value -5.83

Free space 0




44.9 3×( ) 69.55 26.16 f( )log+[ ]–

44.9 3×( ) 46.33 33.91 f( )log+[ ]–

K1HataUrban 2 f 28⁄( )log[ ]2 5.4+ +

K1HataUrban 4.78 f( )log[ ]2 18.33 f( ) 40.94+log–+

60 32.44 20 f( )log––

26


K5

Clutter Offsets

Requirements for optimizationTable 1.4 describes the optimization requirements for each factor.


Hata value 0

Free space 0



Hata value 6.55

Free space 0




Zero 0


Table 1.4 Optimization requirements for factors

K Factor Requirements for OptimizationK1 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


p3 p3T> p3 0.01>

p4 p4T> p24 p24T< p4 0.01>

p3 p3T> p35 p35T< p3 0.01>

27

Technical Note

t.

To create an AMT template1 Select a PGM model in the Propagation window, right-click and choose Edi

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, choose User 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, choose User 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.11 Click the Okumura tab and clear all of the check boxes.

28


k a

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 modelThis 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 method1 In the Propagation window, expand the Propagation Models node, right-clic

drive test and choose Tune.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 to modify the selected 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.

29

Technical Note

6 Do all of the following:■ From the K1, K2, and K4 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 and K2 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, and K4 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.

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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-231The 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:

Lp k f( ) 13.82 10hblog–( ) 44.9 6.55 10hblog–( )10 dkm( ) Clutter Absorption Loss+( )log

+=

Lp LHata Clutter Absorption Loss+=

Lp

hb

f

dkm

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Technical Note

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 factorKnife 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 factorsAn 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 10 f( )for f 150 MHz to 1500 MHz=log+=

k f( ) 46.3 33.9 26.16( ) 10 f( )for f 1500 MHz to 2000 MHz=log+=

hb

dkm

hm

Free Space Loss Diffraction Loss+

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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 componentYou 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


33

Technical Note

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


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


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.

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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

tuning process.

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Technical Note

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