Coverage and Propagation Models

WRAP 0860G 1

Coverage

WRAP 0860G 2

Link budget

Tx Antenna Gain Filters, Feeder, etc.

Transmission Loss Atmospheric Attenuation EIRP Rx Antenna Gain Filters, Cable Loss Tx Transmitter Receiver Rx WRAP 0860G 3

Propagation Models

• • • Ten propagation models are supported: - ITU-R P.526-6 (Detailed terrain) - DETVAG 90/FOA (Detailed terrain) - ITU-R P.370-7 - Longley-Rice - Okumura-Hata/COST-231 - Hata - COST-231 - Walfish - Ikegami - ITU-R P.452-9 - ITU-R P.619

- Free Space - CRC (Detailed terrain), by special licensing only Attenuation due to atmospheric gases can be included (ITU-R P.676-2 for terrestrial, P.618-6 for space) HF Planning with ITS HF software: -VOACAP/ICEPAC/REC533 (point-to-point) -VOAAREA/ICEAREA/RECAREA (point-to-area) WRAP 0860G 4

Propagation mechanisms

FIGURE 1

Long-term interference propagation mechanisms

Tropospheric scatter Diffraction Line-of-sight 0452-01 WRAP 0860G 5

Model Free space Longley-Rice Frequency range

No frequency limitation 20 MHz to 40 GHz

Propagation Models

Terrain dependence Antenna height above ground

No terrain dependence. Gives the same transmission loss in all directions.

No terrain dependence. Terrain influence is given as a terrain roughness parameter to the model, entered by the operator. Gives the same transmission loss in all directions.

The model assumes no ground influence.

0.5 – 3000 m. The 3000 m above ground level antenna height limitation does not significantly reduce accuracy for higher antenna heights.

Calculation speed

Very fast Very fast

ITU-R P.370-7

30 – 1000 MHz

Okumura Hata/COST-231-Hata

150 – 2000 MHz (no hard limit at 2000 MHz – can be used for 2 GHz cellular applications)

COST-231 – Walfish Ikegami

800 – 2000 MHz (no hard limit at 2000 MHz – can be used for 2 GHz cellular applications) Terrain information is taken from the ITU Digitized World Map to determine the path lengths over land and over sea. The operator can enter a terrain roughness parameter. Gives the same transmission loss in all directions, if the path is wholly over land or sea.

One antenna in the interval 1.5 – 40 m and the other antenna 37.5 – 1200 m above ground.

Very fast No terrain dependence. The operator can enter a type of environment (urban, suburban, rural etc.). Gives the same transmission loss in all directions. The distance is limited to 1 – 20 km.

One antenna in the interval 30 200 m and the other antenna 1 above ground.

– – 10 m No terrain dependence. The operator can enter the type of environment and parameters describing the buildings and streets. Gives the same transmission loss in all directions. The distance is limited to 0.02 – 5 km.

One antenna in the interval 4 – 50 m and the other antenna 1 – 3 m above ground.

Very fast Very fast WRAP 0860G 6

Model ITU-R P.526-6 Detvag-90/FOI

Propagation Models

Frequency range Terrain dependence Antenna height above ground

From about 500 MHz to above 100 GHz. For situations where one or both of the antennas are high above ground (such as in ground-to-air and air-to-air links) it can be used from 100 MHz.

Terrain information taken from the height and terrain classification databases. Gives fully terrain dependent transmission loss, however neglecting the electrical characteristics of the ground and ground reflections.

Valid for all antenna heights.

Calculation speed

Fast 10 kHz to above 100 GHz. Ionosphere propagation is not considered.

Terrain information taken from the height and terrain classification databases. Gives fully terrain dependent transmission loss.

Note that Detvag includes a number of selectable models and can be set to be non terrain dependent as well. This is however not the normal use.

The fast methods (non-GR ground wave) have limitations on the maximum antenna height: Frequency Height 30 MHz 100 300 1000 300 m 125 59 26 3000 13

Note that for most practical cases the influence of the ground (apart from diffraction) can be neglected above 1 GHz even at low antenna heights. The default methods of Detvag (“Quick” settings) therefore do not have the above limitations above 1 GHz.

Fast-to-medium for most settings. Very slow when used with the GR methods (for ground wave below about 30 MHz) WRAP 0860G 7

Propagation Models

Model CRC ITU-R P.452-9 ITU-R P.619-1 ITU-R P.676-2 and P.618-6 Frequency range Terrain dependence

30 MHz to above 100 GHz Terrain information taken from the height and terrain classification databases. Gives fully terrain dependent transmission loss.

0.7 GHz to above 100 GHz Diffraction calculations are performed using the P.526 method, giving terrain dependence. Rain scatter parameters are read from the ITU Digitized World Map. Otherwise the model is not terrain dependent.

From about 300 MHz to above 20 GHz. The lower limit is due to neglecting of ionospheric scintillation. The upper limit is due to the modelling of tropospheric scintillation.

No terrain dependence, apart from consideration to shadowing by the earth considered as a sphere.

Antenna height above ground

Valid for all antenna heights.

Calculation speed

Slow The model is intended for stations on the surface of the earth. Antenna heights should be less than a few hundred metres.

Fast for most settings. Slow for very long distances.

The model is applicable for earth space paths, with the space station being at non-geostationary orbit height or above and the earth station being on the surface of the earth, with antenna height less than a few hundred metres.

Very fast 1 – 350 GHz. P.618-6 for space paths does not include the oxygen gap consideration at 60 GHz.

Not applicable. The transmission loss calculated by the atmospheric attenuation models is added to the loss calculated by the selected propagation model.

No antenna height dependence is included (apart from the satellite height for the space path model). This limits the applicability to heights up to a few thousand metres for terrestrial paths.

Very fast WRAP 0860G 8

Propagation Models

Table 4.1:

Default settings for Detvag-90/FOI propagation model (Quick tab,

Low

/

High

accuracy)

Frequency range and Accuracy Method



Below 30 MHz 30 – 1000 MHz

Low High Low High Low

Above 1000 MHz

High

Spherical earth GR Start GR Millington extended Old with conductivity None None None Diffraction No. of obstacles Urban Vegetation None None None None None None Giovaneli 3 Add cover height Add cover height GTD 7 Add cover height Add cover height Giovaneli 3 GTD 7 Add cover height Add cover height Add cover height Add cover height None None Effective antenna height None None None None WRAP 0860G 9

Application Ground-to ground Ground-to-air Air-to-air Earth-to-space Space-to-space Frequency

<30 MHz, ground wave >30 MHz

Propagation Models

Recommended propagation model

Detvag-90/FOI. Quick/Low if terrain data is not available; otherwise Quick/High. Start with very low resolution in Coverage calculations to check the calculation speed before making detailed calculations.

Terrain data available:

Detvag-90/FOI, Quick/Low if antenna height conditions are fulfilled. Otherwise Detvag-90/FOI, Advanced, GTD. CRC (if available) is applicable irrespective of antenna heights.

No terrain data available:

Longley-Rice.

For specific services: Broadcast: ITU-R P.370

Cellular: Okumura-Hata/COST-231-Hata or COST-231 – Walfish-Ikegami Detvag-90/FOI. Quick/High.

<30 MHz, ground wave 30 – 100 MHz >100 MHz >30 MHz (lower frequencies usually of little interest) >50 MHz

Terrain data available:

Detvag-90/FOI, Advanced, GTD. CRC (if available) is applicable irrespective of antenna heights.

No terrain data available:

Longley-Rice

Terrain data available:

ITU-R P.526 is the first choice due to its fast calculation speed.

Detvag-90/FOI, Advanced, GTD. CRC (if available) is applicable irrespective of antenna heights. These should also be used if there is specific need to account for ground reflections to show occurrence of areas of increased transmission loss due to cancellation between the direct ray and ground reflected rays (normally only relevant over water).

No terrain data available:

Longley-Rice Longley-Rice as an overall method at heights where terrain obstructions are not important ITU-R P.526 for cases where the terrain influence due to obstructions are of interest ITU-R P.619. Make sure to select the

Space paths

atmospheric attenuation model.

All frequencies Free space. Note that

Class of Station

should be set to

Space station

account for shadowing by the Earth.

for both stations if the calculation is to WRAP 0860G 10

Coverage

• Single transmitter coverage or Multiple transmitter coverage WRAP 0860G 11

Selectable calculations (Single station)

• Field strength [dBµV/m] • Power flux density [dBW/m 2 ] • Signal strength [dBµV] • Received power [dBm] • Transmission loss [dB] • Clearance [%] • S/I [dB] • Required antenna height [m] • Terrain clearance angle [º] • Neighbour cells, noise & interference limited • Adjacent cell coverage WRAP 0860G 12

Selectable calculations (Multiple stations)

• Field strength [dBµV/m] • Power flux density [dBW/m 2 ] • Signal strength [dBµV] • Received power [dBm] • Best server, noise limited or interference limited • No of servers, noise limited or interference limited • Maximum clearance, minimum clearance [%] • Maximum required antenna height, minimum required antenna height [m] • Composite coverage, S/I [dB] • Number of interferers • Worst interferer WRAP 0860G 13

Best server

• Best Server, noise limited – maximum signal of all stations in the calculation – signal greater than or equal to the receiver sensitivity plus margin • Best Server, interference limited – maximum SIR of all stations in the calculation – signal greater than or equal to the receiver sensitivity plus margin – SIR greater than or equal to the receiver required SIR plus margin WRAP 0860G 14

Number of servers

• Number of Servers, noise limited – signal greater than or equal to the receiver sensitivity plus margin • Number of Servers, interference limited – signal greater than or equal to the receiver sensitivity plus margin – SIR greater than or equal to the receiver required SIR plus margin WRAP 0860G 15

Clearance

• Maximum clearance calculates the clearance from all stations to the antenna at each point and then displays the value which fulfils the criterion for one of the stations. [%] • Minimum clearance calculates the clearance from all stations to the antenna at each point and then displays the value which fulfils the criterion for all of the stations.[%] WRAP 0860G 16

Required antenna height

• Minimum required antenna height gives the required antenna height to fulfil the clearance criterion from all of the involved stations • Maximum required antenna height gives the required antenna height to fulfil the clearance criterion from one of the involved stations WRAP 0860G 17

Probability calculations

• Normally the calculation results are the local mean values, which are the direct output from most of the propagation models. If the Probability check box is checked, the result is adjusted based on the assumption that the signal has a log-normal probability density function. All probability calculations are performed for the contour probability (and not the area probability).

• Standard deviation can be fixed or set by the software (normally 8.3 dB) WRAP 0860G 18

Probability calculations • Fixed level

– Calculation of the probability that a user-defined level achieves. The result can be plotted for different percentages but the level is fixed.

• Fixed probability

– Calculation of the result levels for a given probability. The result is then plotted for different levels but with fixed probability. WRAP 0860G 19

Result Presentation

A three-level result Long-Lat grid Relief background Radio station

WRAP 0860G 20

Resolution

Very Low Resolution

Number of terrain raster points

200x200 = 40 000

Resolution

Number of calculation points for Area Number of calculation points for Line

25x25 = 625. For very rough estimates or calculations involving an extremely large number of transmitters in a smaller area.

25 points on line Low Resolution 400x400 = 160 000 Average Resolution 800x800 = 640 000 50x50 = 2 500. For rough estimates.

50 points on line 100x100 = 10 000. Default setting which is adequate for most purposes. This gives a good visual appearance on screen and printouts, without requiring excessive calculation times.

100 points on line High Resolution Very High Resolution User defined 1600x1600 = 2 560 000 3200x3200 = 10 240 000 200x200 = 40 000. For very detailed calculations.

400x400 = 160 000. For extremely detailed calculations.

200 points on line 400 points on line The resolution given in meters is be entered by the user. The resolution given in meters is be entered by the user. The same resolution is used in both directions.

The resolution given in meters is be entered by the user.

WRAP 0860G 21

Interference limited coverage • It is possible to select different propagation models for the wanted and interfering signal • Applies for the following calculations

– S/I (single station) – Interference limited best server (multi-station) – Interference limited No. of servers (multi-station) – Composite S/I (multi-station) – Number of interferers (multi-station) – Worst interferer (multi-station) WRAP 0860G 22

Population coverage • The total

– number of population that is covered with a certain field strength, received power level etc. – percentage coverage of the total population in a defined calculation area can be calculated.

• Requires a database in the appropriate format, with information on the number of inhabitants within a certain square area.

WRAP 0860G 23

Calculation

Coverage calculation results: Post calculations

Best server…

Description (single RESULT marked)

Not applicable.

Description (multiple RESULTS marked)

Identifies the best server by comparing the result values from all marked results. All the results must be of the same calculation type and based on a calculation for a single station. The results must be of the calculation type Field strength, Signal strength, Received power or S/I. Probability calculations are also possible.

In order to be a best server at a certain location the station must fulfil: • Maximum signal of all stations in the calculation • Signal greater than or equal to a user defined planning level.

Upon executing this command the user is prompted by a dialogue to set/accept the planning level threshold. Composite Number of servers… Not applicable.

Not applicable.

Calculates the composite coverage with the highest value of the selected results as the result. All the results must be of the same calculation type. Single station results and multiple stations results can be used together. The results must be of the calculation type Field strength, Signal strength, Received power or S/I. Probability calculations are also possible.

For single station results Transmission loss results also can be used. The lowest value is presented as the result.

Identifies the number of servers by comparing the result values from all marked results. All the results must be of the same calculation type and based on a calculation for a single station. The results must be of the calculation type Field strength, Signal strength, Received power or S/I. Probability calculations are also possible.

In order to be accepted as a server the station must have a value exceeding the planning level. Upon executing this command the user is prompted by a dialogue to set/accept the planning level threshold. WRAP 0860G 24