MLinkPlanner 1.2

Point-to-Point and Point-to-Multipoint Microwave Link Planning Software

Microwave link planning software user interface

User Manual

Part 1   Part 2   Part 3   Part 4
Reflection Analysis

Reflection analysis allows the user to identify possible specular reflection points on the hop and evaluate the application of various specular reflection reduction methods.
To open the Reflection Analysis window, click the corresponding button on the main panel. The left-hand part of the panel will be disabled. To select Reflection Analysis for another hop, return to the Map View mode.


k-factor                                              k-factor, for which the reflection points are searched
Polarization                                       Vertical 
                                                            Horizontal

                                                            To reduce the effect of the reflected wave, it is recommended to select                                                                              vertical polarization
Reflecting surface type                   Sea water
                                                            Fresh water
                                                            Wet ground
                                                            Very dry ground
                                                            Ice

                                                            The type of surface from which the reflection occurs. Each of the above                                                                            surface types has its own values of Relative dielectric constant and Electrical                                                                  conductivity
Relative dielectric constant           Relative dielectric constant is a dimensionless parameter. Is automatically                                                                      determined depending on the Reflecting surface type from above, but can be                                                                  modified by the designer
Electrical conductivity                     Electrical conductivity [ohm‐1 m‐1]. Is automatically determined depending on                                                               the Reflecting surface type from above, but can be modified by the designer
                                                            Consider clutters on the reflected paths    If this check-box is active, then                                                                          when the incident or reflected rays intersect with ground obstacles (forest or                                                                  trees), these rays will be screened

The path profile in the upper part of the window will display all possible direct and ground-reflected rays for the Main-Main paths, and in a space diversity configuration for the Main-Diversity and Diversity-Main paths. The table below will show the distances to and clearance at each of the reflection points. It is recommended that reflection points be determined for large k-factor values (at least 10).


You can view Relative Rx Power vs. k-factor chart for any reflection point and any of the Main-Main, Main-Diversity or Diversity-Main paths by clicking on the desired point in the table. Note that you need to specify the beamwidth for each of the antennas in Site A and Site B to calculate Relative Rx Power vs. k-factor chart.

 

In addition to Relative Rx Power vs. k-factor, you can also display Time Delay vs. k-factor chart. On this plot the relative signal delay in nanoseconds between the direct and reflected signal is displayed for each of the Main–Main, Main–Diversity or Diversity–Main paths. If the reflected signal delay is greater than 10-20 nanoseconds, performance problems on high capacity systems can occur.

microwave link design tool Reflection analysis

How to Do Path Reflection Analysis 

Figure 14. Reflection analysis

Estimation of Specular Reflection Reduction without Using Space Diversity

If there is specular reflection along the path and you are not going to use space diversity, the application can estimate the effectiveness of the following methods for reducing the effect of the reflected ray on the resulting signal for systems without space diversity recommended in Rec. ITU-R P.530-17:


-    increase of path inclination;
-    shielding of the reflection point;
-    moving of the reflection point to a poorer reflecting surface;
-    reduction of path clearance;
-    choice of vertical polarization.

 

In most cases, these methods (except for the last one) are limited to selecting the primary antenna height on the right or left.

Estimation of Specular Reflection Effect with Space Diversity

The most efficient way to eliminate the effect of specular reflection is to use space diversity techniques. The most often used technique is vertical space diversity. MLinkPlanner allows you to determine receive antenna heights with enough spacing to maintain an uncorrelated direct and reflected signal, so that when the receive signal level for the primary antenna is zero (in fade), the signal is near the peak for the diversity antenna, and vice versa.


The right-hand part of the window displays the heights of diversity antennas determined based on optimum antenna spacing as per Rec. ITU-R P.530-17, i.e. the case when received signal levels at the primary and secondary antennas must display a maximum difference (maximum and minimum) across the full range of the k-factor to minimize the effect of specular reflection on the received signal level.


To estimate the effect of space diversity, perform the following steps:


1.    Select a space diversity configuration for both Site A and Site B (in the Map View mode).
2.    Select a reflection point for each path using the mouse button.
3.    Select one of the optimum heights of the secondary antenna from the series in the right section of the window using the mouse button.


You will then view the received signal level for each antenna on the chart. By changing the antenna height, you can see how the received signal level will change.


In a space diversity configuration, if the vertical spacing between antennas is less than 200 times the wavelength (which is a common rule for reducing the effect of multipath propagation on the performance indicators), a warning will appear next to the spacing on the profile and its value in meters (i.e., 200 times the wavelength) will be displayed.


To determine heights of primary and secondary antennas in a space diversity configuration, the following conditions must be met:


1.    The maximum difference between the received signal levels of the primary and secondary antennas must be observed across the full range of k-factor to eliminate the effect of specular reflection (if any).
2.    The primary and secondary antennas must be at least 200 times the wavelength to eliminate the effect of multipath propagation.
3.    The primary and secondary antennas must satisfy the clearance criteria described in Rec. ITU-R P.530-17.

Diffraction Analysis

Diffraction analysis allows the user to estimate diffraction losses due to obstacles on the hop. Diffraction losses may be due to the inability to meet the clearance criteria as per Rec. ITU-R P.530-17.


To open the Diffraction Analysis window, click the corresponding button on the main panel. The left-hand part of the panel will be disabled. To select Diffraction Analysis for another hop, return to the Map View mode.


MLinkPlanner uses the following diffraction methods as per Rec. ITU-R P.526-13 Propagation by Diffraction:


Single Rounded Obstacle—for diffraction over one obstacle;
Multiple Isolated Cylinders—for diffraction over irregular terrain which forms two or more obstacles.


The method to be used is selected by the application automatically based on the path profile of the hop.


Diffraction losses are calculated for a single path (by default, for the Main–Main path). If you want to estimate diffraction losses for other paths (Main–Diversity or Diversity–Main paths), you need to change the height of the corresponding antennas.

microwave link design tool Diffraction

How to Do Path Diffraction Analysis

Figure 15. Diffraction analysis

Displayed items    
Ray                                                                    Show the ray line between antennas
Stretched string                                              Show line Stretched string. This identifies the sample points which would be                                                                                           touched by a string stretched over the profile from the transmitter to receiver
Obstructions                                                    Show obstruction identifiers. The obstruction  identifiers are shown in figures on a                                                                                 yellow background
Radiuses of the cylinders                              Show Radius equal to the radius of curvature at the obstacle top
Sub-path obstructions                                   Show obstruction numbers on the Sub-path. The obstruction numbers on the                                                                                         Sub-path are shown on a blue background
60%F1 for sub-path                                        Show 60 % of the first Fresnel zone

 

Projections of rays intersecting 

above obstacles                                              Show Projections of rays intersecting above obstacles
Baselines                                                          Show Baselines
60%F1 for baselines                                       Show 60% of the first Fresnel zone for baselines

 

Parameters of Diffraction Analysis    
k-factor                                                             к-factor for Diffraction Analysis
Add clutters to terrain                                    If this check-box is active, then all the clutter (trees and buildings) is counted                                                                                           as obstructions on the profile
Minimum space between points

for one obstruction                                        This parameter can be adjusted within 250 m–10 km for the more accurate                                                                                                   approximation of obstruction
For reference: the value of k-factor

exceeded for approximately 99.9%

of the worst month (temperate

continental climate) is ___                            Value of k-factor exceeded for approximately 99.9% of the worst month for the                                                                                        current  hop according to Figure 2 in Rec. ITU-R P.530-17

 

Diffraction Loss According to Rec.

ITU-R P.526-13    
Obstruction No.                                              Identifier Number of Obstruction
Sub-path obstruction No.                             Identifier Number of Obstruction on the Sub-path
Correction factor Cn                                      Correction factor Cn according to Rec. ITU-R P.526-13
Location (km)                                                  Location of Obstruction (km)
Clearance (m)                                                 Clearance at the Obstruction (m)
v                                                                        Single dimensionless parameter according to Rec. ITU-R P.526-13
Radius (km)                                                    The radius of the Obstruction, km
Loss (dB)                                                         Diffraction losses at each obstruction (dB)
Total                                                                 Total Loss (dB)

When you calculate performance characteristics, diffraction losses are calculated automatically for each path based on the antenna heights and the following parameters: k-factor value, Add clutters to terrain, Minimum space between points for one obstruction. These parameters are saved in the project file and can be defined for each hop individually.

microwave link design tool Diffraction analysis (with clutters)

Figure 16. Diffraction analysis (with clutters)

The calculated diffraction losses are taken into account when determining the received signal level and the fade margin.

Planning Point-to-Multipoint networks

 

In the Point-to-multipoint tab, you can do:

  1. Coverage Study for Base Stations;

  2. Availability calculation for each of the hops Base Station - Subscriber Station.

 

To calculate radio coverage, it is sufficient to enter the parameters of the base station (s) and the typical parameters of the subscriber station - “subscriber station installation”, that can be located anywhere in the study area.

For the point-to-multipoint link availability calculation (see point-to-multipoint links availability calculation), it is also necessary to specify the location of each of the subscriber stations, specify to which base station each subscriber station relates, and enter all necessary detailed parameters of base stations and subscriber stations.

Base Stations

 

To create a base station, enter the name of the base station in the “Name” field, then right-click on the “Site” field and select the desired site from the list that appears. After that, the Base Station will appear on the map, while the width of the angular sector and its direction will correspond to the direction and width of the antenna pattern.

Figure 17. Creating a new base station

To select a Base Station, click on the corresponding row in the hop table.

To move Base Stations up and down the table, use             and              buttons. To remove a Base Station, click            .

 

Note that if a site is associated with a Base Station (or several Base Stations), removing or renaming the site in the Sites tab will remove all Base Stations associated with this site.

When clicked, the Base Station will be displayed in the center of the basemap.

The coverage study for a Base Station will only be carried out if the checkbox, located to the left of the Base Station name, is active.

The equipment parameters for the selected Base Station are displayed below in the Base Station tab.

Figure 18. Base Station equipment parameters

Toolbar:

Copy equipment parameters from Base/Subscriber Station—copy all the data from Base/Subscriber station tab


Copy equipment parameters to Clipboard—copy to clipboard all the data from Base/Subscriber Station.


Paste from Clipboard—paste data from the clipboard.


Load equipment parameters from file—load radio equipment data from data file *.ptmp

Save equipment parameters to file—save radio equipment data file in data file format *.ptmp


Save current parameter values as a template for future use—save in a template all the data for use on new Base/Subscriber Stations.

Global Active Base Stations parameter change - a feature that allows you instantly change the parameters of any base station in accordance with the parameters of the current sector. 

The procedure for performing group parameter changes:


1. Mark BS as active, whose parameters need to be changed;


2. Set the required parameter values in the current BS;


3. Click the button            , select in the list the parameters that need to be changed in the previously marked active BS, and click the OK button.

Figure 19. Global Active Base Stations parameter change

Below is the description of all input parameters that may need to be specified.


01. Main    
Radio equipment                                         Radio equipment code. Information only
Frequency, MHz                                           Mean frequency of the Base Station
 

02. Antennas and loss
Antenna model and pattern                       Antenna model code. Information only. To select antenna pattern,                                                                                click the button next to the entered antenna model code and load the                                                                          file in the  *.msi or *.nsma format.
Antenna height, m                                       Antenna installation height relative to ground level, m.
                                                                        You can also change the antenna height in the profile window
Antenna azimuth, deg                                 Antenna azimuth, degree
Antenna gain, dBi                                         Antenna gain, dBi
Feeder loss, dB                                             Feeder loss, the default value is 0 dB
 

03. Radio specifications
Use adaptive modulation                           YES or NO.    The selected type is automatically copied to the                                                                                          remote site. In the case of adaptive modulation (YES), you need to                                                                              enter the values of Tx power and Rx threshold for each modulation                                                                              type in the table that appears below

 

Without adaptive modulation

 

Modulation                                                    Modulation type. Information only
Capacity, Mbit/s                                           Channel capacity, Mbit/s. Information only
Tx power, dBm                                              Transmitter power, dBm
Rx threshold, dBm                                        Receiver threshold level, dB

 

With adaptive modulation
 

Figure 20. Base station radio specifications with ADM

The meaning of the parameters for each type of modulation and coding is the same as in the previous table. This table contains all common types of modulation and coding for modern point-to-multipoint equipment. If any modulation mode is not used in the equipment, then the corresponding line can be left empty. Using the Active checkbox, you can include or exclude different types of modulation from the calculation, the hardware parameters for which are defined.

 
Subscriber Stations

 

To create a Subscriber Station, select in the Base Station table, the Base Station to which the Subscriber Station will be assigned to. Then click on a row on the Subscriber Station table and then right-click on the “Site” field and select the desired site from the list that appears. 

Figure 21. Creating a new subscriber station

To move a subscriber station up and down the table, use           and            buttons. To remove a subscriber station, click           .
 

         - Sort Subscriber Stations in alphabetical order;

 

To select a link, click on the corresponding row in the Subscriber Station table.


When clicked, the link will be displayed in the center of the basemap.


You can also select a link by double-clicking on it on the basemap.

 

The equipment parameters for the selected Subscriber Station are displayed below in the Subscriber Station tab.

Figure 22. Subscriber Station equipment parameters

The set of equipment parameters for the Subscriber Station is the same as the Base Station parameter set, except that you do not need to specify the frequency and the antenna pattern. It is assumed that the frequency ranges of Base Station and Subscriber Station are the same, and the Subscriber Station antenna is aimed exactly at Base Station. The polarization of the Base Station and Subscriber Station antennas is also assumed to be the same.

Figure 23. Subscriber station radio specifications with ADM

Copy selected Rx thresholds to Coverage Study levels – when this button is clicked, Rx thresholds information is copied for the selected modulation modes to the Coverage Study Details menu for further use in the Coverage Study.

Coverage Study

 

The coverage study calculates the estimated coverage of the base stations – i.e., the study approximately determines the areas where the subscriber stations can be located and gives a rough estimate of the achievable link capacity in this location. To ensure the correctness of the decision to place the subscriber station in a particular location, and to determine the exact height and type of the subscriber station antenna for the required link capacity, it is necessary to perform the detailed coverage calculation.


Coverage study is performed under the following conditions:


1.    The parameters entered for each of the base stations in the Base Station tab are used for the coverage calculation.
2.    A typical "Subscriber station installation" is used in the calculations for predicting coverage in the entire study area. The typical subscriber station parameters are entered in the Coverage Study Details menu.
3.    The calculations do not take into account the excess path loss due to clutter loss (buildings and trees).

 

Before starting a coverage area study, you must first specify the parameters of the Base Stations that will be involved in the study and set those Base Stations to Active. Refer to Base Stations section for information on setting Base Stations parameters. Note! The coverage study for Base Station will only be carried out if the checkbox, located to the left of the Base Station name, is active.


To configure the Coverage Study options, go to the Coverage Study Details menu

How to Do Radio Coverage Study for Point-to-Multipoint

Base Stations

Figure 24. Coverage Study Details for Received Power at subscriber stations study

Area study type                                                 Received Power at subscriber stations

                                                                             Strongest (Most likely) Server

                                                                             C/I+N at subscriber stations

Base Station Parameters

 

Transmit Power, dBm                                        Оne power value for all base stations, dBm

Use BS transmitter power data                        Use the power settings for each of the base stations specified in the Base Station                                                                                 tab. If adaptive modulation is used at the base station, the maximum power from                                                                                   the Base station equipment parameters table will be used

Study radius, km                                                 Maximum study radius from Base Station, km

 

Subscriber Station installation

 

Antenna height, m                                              Antenna installation height relative to ground level, m.

Antenna gain, dBi                                               Antenna gain, dBi

Feeder loss, dB                                                   Feeder loss, default value is 0 dB

 

Margin, dB                                                           Prediction confidence margin of the calculation results for area study, dB

Color transparency (0-250)                              Color transparency of the signal level (0-max transparency, 255 – no transparency)

Tx power, dBm                                                    Transmitter power, dBm

Low resolution                                                    Low resolution calculation (less computation time)

High resolution                                                   High resolution calculation (more computation time)​

Received Power at Subscriber Stations


Received power map shows those areas where a given signal power level is present at the subscriber stations receiver (downlink).


Number of levels                                                The number of signal levels from 1 to 8
Color                                                                     The color of the signal level
Values, dBm                                                         Received power level, dBm
Description                                                          The text field as an annotation on each signal level, for example, 256-QAM 5/6 400                                                                                 Mbit/s

To perform the coverage study, click the button Calculate Coverage

Figure 20. Coverage Study Details for Strongest Server

Figure 25. Received Power at subscriber stations coverage

 

Strongest (Most likely) Server


The strongest server map display is a map showing the base station supplying the strongest received signal at all locations on the basemap.

              Figure 26. Coverage Study Details for Strongest Server study

 

Required service threshold, dBm                       This is the minimum acceptable signal strength
                                                                                 required by the receiver
Apply automatic color assignment                   The program automatically assigns colors to the base stations in the study, and                                                                                     then color fills the map according to these color assignments
Use colors from the table                                   The colors for the base stations will be assigned in accordance with the                                                                                                   frequency table
Fill the table with frequencies of BS                 Fill the table with the frequencies specified in the parameters of the base stations

Figure 27. Strongest (Most likely) Server study

 

To perform the coverage study, click the button Calculate Coverage

 

C/(I+N) at subscriber stations

 

The carrier-to-interference+noise ratio, C/(I+N) or CIR, is one of the most important quantities used in assessing system performance. The quantity CIR is more completely written as:​

where C is the power of the signal from the strongest server at a location, Ik is the power of each of the other k signals at that location, NR is the receiver noise power, and K is the total number of transmitters which cause interference at this location. Ik is only computed for transmitters that are using a channel that is a co-channel or adjacent channel. If the closest channel in use by the interference sector is an adjacent channel, then the interference contribution by the sector is reduced in amplitude by the adjacent channel rejection factor.

Channels are defined as adjacent if the difference between the center frequencies of the channels is less than or equal to one bandwidth.

Channels are defined as co-channel if the difference between the center frequencies of the channels is zero sharp.

The receiver noise power is calculated by multiplying the receiver effective noise bandwidth by the power noise density as represented by the receiver noise figure.

CIR is calculated by first finding the strongest received signal power from any transmitter at each location. In then calculates the sum of the receive signal powers from all the other transmitters which also have relevant signal levels at the location. After the sum of the interference is found, the noise power is calculated and the ratio is found.

Note that once the strongest signal has been identified, the directional receive antenna at each location is assumed to be pointed toward the transmitter from which the strongest signal is received. The received signal from the other (interference) transmitters is then found using the off-axis gain of the receive antenna assuming an orientation toward the strongest signal transmitter.

                       Figure 28. Coverage Study Details for C/(I+N) at subscriber stations study

 

Required service threshold, dBm                   This is the minimum acceptable signal strength
                                                                             required by the receiver
Browse MSI or NSMA                                      Choose the antenna pattern file for Subscriber Station Installation 
Use adjacent channel interference                If the checkbox is active, the calculation will take into account the contribution of                                                                                   adjacent channels to interference
Adjacent channel rejection, dB                      Adjacent channel rejection, dB
Channel bandwidth, MHz                                Channel bandwidth, MHz
Use receiver noise power level                      If the checkbox is active, the calculation will take into account the power of receiver                                                                               noise
Receiver noise figure, dB                                Receiver noise figure, dB
Equivalent noise bandwidth, MHz                Equivalent noise bandwidth, MHz

 

If the checkboxes "Use adjacent channel interference" and "Use receiver noise power level" are not active, the calculations will take into account only the co-channel interference

 

To perform the coverage study, click the button Calculate Coverage

Figure 29. C/(I+N) at subscriber stations study

 

Creating a coverage report

MLinkPlanner allows you to create a coverage report as an interactive web page. To save the web page, click the "Create coverage report" button. The index.html file (this is a page script), the bs.png file (the base station icon) and the folder of the coverage tile pyramid in the format {Z} / {X} / {Y} will be saved to the folder selected by the user. To view the result, open the index.html file in any web browser. This page can also be placed on a web server for viewing in any browser and on any of the operating systems (Windows, Mac, iOS, Android, Linux).
 

Examples of pages are listed below (open in a new window).

Figure 30. Coverage report

The web page allows:

- Choose a base map from 4 different base maps;

- Change the map zoom;

- Display the legend;

- Display the map zoom and the map scale and current coordinates of the cursor (in the decimal system and DMS);

To view an interactive web page, you need an Internet connection.

The folder with the pyramid of tiles can be connected to any GIS that supports work with tiles (for ex. QGIS, ArcGIS, MapInfo), which will demonstrate the result of calculating the radio coverage as a layer on any GIS.