Planet General Model Technical Notes

Cover Page

for Mentum Planet version 5.4

Copyright © 2010 Mentum S.A. All rights reserved.  Notice

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 any format or media, in whole or in part, without the prior written consent of  Mentum S.A. Information contained in in this document supersedes that that found in any previous manuals, guides, specifications data sheets, or other o ther information that may have been provided or made available to to the user. This document is provided for informational purposes only, and Mentum S.A. does not warrant or guarantee the accuracy, adequacy, quality, validity, completeness or suitability for any  purpose the information information contained in this document. document. Mentum S.A. may update, update, improve, and enhance this document and the products to which it relates at any time without prior notice notice to the user. MENTUM S.A. MAKES MAKES NO WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, THOSE OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, WITH RESPECT TO THIS DOCUMENT OR THE INFORMATION INFORMATION CONT C ONTAINED AINED HEREIN. Trademark Acknowledgement Mentum, Mentum Planet and Mentum Ellipse are registered trademarks owned by Mentum S.A. MapInfo Professional is a registered trademark of of PB MapInfo Corporation. RF-vu is a trademark  owned by iBwave. This document may contain other trademarks, trade trade names, or service marks of  other organizations, each of which is the property of its respective owner. Last updated June 10, 2010

Copyright © 2010 Mentum S.A. All rights reserved.  Notice

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 any format or media, in whole or in part, without the prior written consent of  Mentum S.A. Information contained in in this document supersedes that that found in any previous manuals, guides, specifications data sheets, or other o ther information that may have been provided or made available to to the user. This document is provided for informational purposes only, and Mentum S.A. does not warrant or guarantee the accuracy, adequacy, quality, validity, completeness or suitability for any  purpose the information information contained in this document. document. Mentum S.A. may update, update, improve, and enhance this document and the products to which it relates at any time without prior notice notice to the user. MENTUM S.A. MAKES MAKES NO WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, THOSE OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, WITH RESPECT TO THIS DOCUMENT OR THE INFORMATION INFORMATION CONT C ONTAINED AINED HEREIN. Trademark Acknowledgement Mentum, Mentum Planet and Mentum Ellipse are registered trademarks owned by Mentum S.A. MapInfo Professional is a registered trademark of of PB MapInfo Corporation. RF-vu is a trademark  owned by iBwave. This document may contain other trademarks, trade trade names, or service marks of  other organizations, each of which is the property of its respective owner. Last updated June 10, 2010

Planet General Model Technical Note

Introduction The Planet General Model is a good propagation model to use for macro-cell  planning. It is best best used for frequencies between between 150 and 2000 2000 MHz where the distance between the transmitter and the receiver ranges between 1 and 100 kilometers. Ideally, Ideally, when using this th is 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. differ. On one hand, when Planet DMS  performs  performs predictions, predictions, it calculates 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 profile is used by the  propagation model to calculate the path path loss to that point. 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 Earth’s curvature. A radius of 4/3rds of the Earth’s Earth’s true radius (4/3 x 6300km = 8400 km) is often used, although this can  be changed in the Planet Planet DMS Model Editor. On the other hand, when Mentum Planet performs predictions, it calculates a  prediction for each pixel pixel along radials radials in the prediction area. Then, using interpolation, Mentum Planet generates predictions in the prediction area on a  per pixel basis. basis. This results in better better control of the the calculation time/accuracy time/accuracy ratio; however, however, for this reason, there may be slight differences between 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 model The received signal strength at the mobile is given by the following equation.  P  RX  =  P TX  + K 1 + K 2 log ( d ) + K 3 log ( H ef f ) + K 4 Di ff ra ct io n + K 5 log ( H ef f ) log ( d ) + K 6 ( H meff ) + K CLUTTER

Where  P  RX 

is the receive power in dBm

 P TX 

is the transmit power (ERP) in dBm.

 K 1

is the constant offset in dB.

is the multiplying factor for log(d). With the two piece model, both  K 1 and  K 2 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.  K 3 is the multiplying factor for log( H ef f ). It compensates for gain due to antenna height.  K 2

 K 4

is the multiplying factor for diffraction calculation.

 K 5

is the Okumura-Hata type of multiplying factor for log ( H ef f ) log ( d ) .

is correction factor for the mobile effective antenna height gain ( K 6 H ef f ). d is the distance, in meters, of the receiver from the base site.  H ef f  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,  K 4 is required.  K CLUTTER is the gain in dB for the clutter type at the mobile position in Planet DMS . In Mentum Planet,  K CLUTTER represents a loss.

 K 6

 H meff  is the mobile effective antenna height.

4

Planet General Model Technical Note

Effective antenna heights Effective antenna height at the transmitter  The effective antenna height ( H ef f ) 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 ( H ef f ) is set equal to the base site height above ground. Spot height

If  H 0 b > H 0 m then Hef f  =  H b + H 0 b –  H 0 m If H 0 b ≤ H 0 m then Hef f  =  H b Where

is the antenna height above ground at the base site.  H 0 b is the terrain height above sea level at the base site.  H 0 m is the terrain height above sea level at the mobile site.  H b

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 ( H ef f ) 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 slope algorithm. 5

Technical Note

The slope algorithm is  H ef f 

= ( h 1 – h 2 ) + ( K × d )

Where

is the ground height at transmitter + antenna height. h 2 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. h1

d  d  s T   x h1  H eff 

 R x

h2

Slope K 

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.

6

Planet General Model Technical Note

Profile

The profile algorithm calculates an average height along the profile between the transmitter and receiver.  H ef f  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 ■

■

■

 H ef f  =  H transmitter + H  g ro un d 

Where  H transmitter  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  H ef f  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 transmitter + H  gr o un d  – averageheight 

7

Technical Note

Where  H transmitter  is

the antenna height on the mast  H  gr ou nd  is the height or DTM height of the base above sea level average height is given by: sum of pixel heights along profile from 3km to distant point -----------------------------------------------------------------------------------------------------------------------------------------------number of pixels along this profile

(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: sum of pixel hights along profile from 3km to 15km ----------------------------------------------------------------------------------------------------------------------------number of pixels along this profile 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 sum of pixel heights along profile from base of antenna to po -------------------------------------------------------------------------------------------------------------------------------------------------number of pixels along this point

(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 sum of pixel heights along profile from 3 km to 15 km ---------------------------------------------------------------------------------------------------------------------------------number of pixels along this profile User-defined start/end points

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

8

Planet General Model Technical Note

 Absolute spot height This algorithm uses the equation: H ef f  =  H b +  H 0 b –  H 0 m The absolute value of  H 0 b –  H 0 m is used. Effective antenna height is not limited to H b as the mobile height ( H 0 m ) goes above the base height ( H 0 b ).

Effective antenna height at the mobile The standard propagation model uses the mobile effective antenna height together with a linear correction factor ( K 6 ).  H meff  = ( h 0 m + h m ) – h 0 b

The following figure shows how these heights are calculated. base mobile h0b

hm h0m

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, ci is calculated. The obstruction position, d i is also recorded. From these variables, v i , the argument of the Fresnel integral is calculated. vi

2 d  = c i -------------------------d i λ ( d – d i )

9

Technical Note

Where λ is the wavelength and d is the terrain slope distance. A value of  vi 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. ∞

2 1----------+ j  –  2  j v ( ( π  ⁄  ) ) = dv × ∫e 2

 E  ----- E 0

vi

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

vi

< 2.0

= 20 × log  E  ----- E 0

Where the value of vi is greater than or equal to 2.0, an approximation is used.  E  ----- E 0

0.225 = ------------vi

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 ci , d i and d are used in the diffraction equation as before. Edge A Edge B

ci

di d Mobile

Base Site Figure 3 Obstruction Loss, Edge A

For edge B, the variables cb , following figure.

d am

Figure 4 Obstruction Loss, Edge B

10

and

d ab

are similarly used, as shown in the

Planet General Model Technical Note

Edge A Edge B cb

dab dam Base Site

Mobile

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

11

Technical Note

Table 1.1 Path loss (continued) vi

Ploss

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

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, d t . Where dt = dh, when dh > 90.3953 Otherwise, dt = dhata Where

d h

=

a

0 - ( h pc s + h mw ) 2 ----------1000

and d h is the transhorizon distance in km. a 0 is the effective earth radius in km. h pc s and h mw PCS and MW Receiver antenna heights above average terrain.This applies if the height is greater than 5m, otherwise it is set at 5. d hata

=  – 115 + 105 log d h

Where

d hata is the Hata Merge Distance in km.

12

Planet General Model Technical Note

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

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

Where

 L50 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) - d h is defined above. and  N ( H, h )

= 20 log ( 5 + γ H ) + 4.343 γ h

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

13

Technical Note

The climate types are: 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

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

=  L 50 + cq L 90

Where

 L 90

 – 4

 – 0.137 h

=  – 2.2 – ( 8.1 – 2.3 × 10  f ) e

and cq is taken from the following table: q

50

80

90

99

99.9

99.99

cq

0

0.67

1

1.82

2.41

2.90

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:  L q

=  L 50 + L c – c q L 90

Where

 L c equals

0.07 × exp [ 0.055 × ( G T  + G R ) ]

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

14

Planet General Model Technical Note

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: Receiver

Base Station L

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

■

■

■

15

Technical Note

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 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

Planet General Model Technical Note

Physical

hmax

Rx

b

Rb Modelled

hmax

b Rx

Rb

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.

17

Technical Note

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(log10hte)2 + B(log10hte) + C Where

hte is the effective base station antenna

height. Calculate this using the

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

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(log10Δh)2 +3.538(log10Δh) +3.105 Where

Δh is the difference in 10% and 90% heights over a distance X along the  profile from the receiver to the transmitter.

18

Planet General Model Technical Note

10%

Δh 90%

X

Figure 6 Rolling hilly correction factor  Where

Δh> 20m and number of “peaks” greater than or equal to 3. You can choose to set the distance X in 3 ways: 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. 1

Rolling hilly correction fine factor (K hf ) This is the rolling hilly correction fine factor: K hf  = -1.4191(log10Δh)2 + 14.0544(log10Δh) -10.727 This correction factor is only applied at the top of a hill or at the bottom of a valley. Where

Δh 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) where Δh > 10m  K hf (position of undulation/m) = 0.0 where Δh 60

-0.009411

0.7620

0.22

=30

-0.013400

0.6313

-0.63