Interference analysis

MFN network analysis with ICS telecom

Interference due to one interferer

Interference analysis:

C/I Mode – theoretical consideration

Tx1 is considered as interfered by Tx2 on the point M if :

C1 (dBµV/m) > Threshold (dBµV/m) and

C1-C2 (dB) < C/I Required (dB) – RXAPA (dB) - XPD (dB)

Therefore, we talk about the Nuisance field strength (NFS) delivered by Tx2 at the receiver’s location relatively to Tx1 which is defined by the following formula :

NFS (dBµV/m) = C2 (dBµV/m) + C/I Required (dB) – RXAPA (dB) - XPD (dB)

Interference due to several interferer



In this case, two different definitions of interferences can be used



Single interferers mode:

Tx1 is considered as interfered at the point M if :

C1 (dBµV/m) > Threshold (dBµV/m) and

C1 (dBµV/m) < Max j



1 (NFS) (dBµV/m)

Summed interferers mode (power sum):

Tx1 is considered as interfered at the point M if :

C1 (dBµV/m) > Threshold (dBµV/m) and

C1 (dBµV/m) < Sum j



1 (NFS) (dBµV/m)

Sum(NFS) is defined by the following formula, where NFS(j) is the NFS due to the j-th interferer expressed in dBµV/m:

Sum(NFS) = 10 x Log10(Σ j



1

10 NFS(j)/10 )


C/I Mode – launch the function

To perform an interference calculation, the coverage of all the considered stations have to be calculated previously!

• Define the protection ratio values

• Define the receiving antenna pattern:


C/I Mode – set the protection ratio parameters

• Priority system

• Always check the values applied


C/I Mode – set the protection ratio parameters

• The protection ratio values can be defined in a curve, set by the user (priority 1 and 3)

• The protection ratio values can be extracted from recommendations - ITU, FCC,

ETSI… (priority 2)

• Cross-polar discrimination: This parameter, also called XPD, is set by the user and decreases the protection ratio when the victim and the interferer do not have the same polarization.


C/I Mode – different ways to consider the interferences

In ICS Telecom, there are three main ways to consider the interferences:

The first one is the interference + best server mode

In this mode, a pixel will be considered as interfered if all the received signals are interfered. If the point is interfered, the displayed value is 255, otherwise, the displayed value is the number of the station transmitting the best signal on this point

• This mode can be used if the transmitters broadcast the same program



The second one is the global interference mode

In this mode, a pixel will be considered as interfered if at least one received signal is interfered. If the point is interfered, the displayed value is 255

• This mode can be used if the transmitters broadcast different programs



The third one is the Network ID mode

In this mode, a point will be considered as interfered if at least one program is interfered on this point. The list of programs is determined by all the distinct values of Network ID among the activated stations. If the point is interfered, the displayed value is 255, otherwise, the displayed value is the number of distinct programs received on this point

• With mode the user check on each point, if all the programs are received without interferences.

It is used to study a network broadcasting several programs


C/I Mode – Interference + Best Server mode

Exercise 1: analysis of analog network versus analog network a. Set the network

We consider that the analog network broadcast the same program

• Load the existing network

• 6 analogue transmitters

5 from the BRIFIC

1 new site

The patterns have been adapted.

The exercise is done with 4 channels.

The coverage calculation has been performed with a deterministic model (ITU-R 525)



Exercise 1: Analysis of analog network versus analog network b. Definition of the analog parameters

Stations parameters

1 PADANG PAUH 100.13000 6.29000

2

Name

BKT DEDAP

Longitude X Latitude Y Code Frequency (MHz) Channel Power (W) Ant H (m)

100.45060 5.48570

4DMS

4DMS

623.25

631.25

40

41

42000

126

122.00

18.00

3 GUNUNG RAYA 99.49160 6.22060

4 GUNUNG JERAI 100.26120 5.47160

5 BUKIT LARUT 100.48210 4.51290

6 New Site 100.48216 4.32526

4DMS

4DMS

4DMS

4DMS

639.25

631.25

639.25

647.25

42

41

42

43

11200

260000

6300

200

91.00

137.00

30.00

35.00



Exercise 1: Analysis of analog network versus analog network c. Calculate the interferences

• Do not take in consideration the Rx antenna discrimination

• All the activated stations are considered as

Wanted and Unwanted in turn

Interferences are displayed in pink

The non-interfered signal is displayed as

Best Server



Exercise 1: Analysis of analog network versus analog network d. Population analysis (1/3)

• Launch the population analysis function- Filter on value 255 (interference value)

• Calculate the population interfered inside each polygon

• Calculate the total population interfered




Calculate the area interfered with the filter function

Population Area (km²)

Analog network interferences 424 039 11 127




Take in consideration the Rx antenna discrimination

(ITU recommendation 419)

Analog network interferences (Rx ant.)

Population

130 828

Area (km²)



Exercise 1: Analysis of analog network versus analog network e. Analyze on specific points (1/4)

Use the button “WAY” to know exactly the situation on one point

Define the protection ratios.

• Set the same value as for the one used for the interference map




In this mode:

• All the stations need to be activated

• The receiving antenna pattern is not taking in account




At this point, we know that:

• One transmitter is received over the threshold: Tx5 with a FSR=81dBμV/m

• Tx5 is interfered by Tx3 with a FSR=32dBμV/m




The protection ratio defined for interference between

Tx5 versus Tx3 is 52dB (Co channel case)

Thereby, we can manually check the calculation:

FSR

5

– FSR

3

= 81 – 32 = 49dB => 49<(C/I) required

(52) => The point is interfered



Exercise 1: Analysis of analog network versus analog network f. Draw a profile



Exercise 1: Analysis of analog network versus analog network g. Site by site analysis

To study the influence a network on another one, deactivate the network considered as Unwanted.

There is two ways to consider the activated stations:

• Activated wanted station mode: Only de-activated stations are considered as interferers. The activated stations does not interfered between themselves.

• Activated + Deactivated mode: both activated and deactivated stations are considered as interferers



Exercise 1: Analysis of analog network versus analog network g. Site by site analysis

Isolate the station to analyze

• In this case, we can chose the “Activated wanted station mode” or the “Activated +

Deactivated mode”, the result will be the same

Interferences in pink



Exercise 1: Analysis of analog network versus analog network g. Site by site analysis - example

Exercise: Calculate the population without interference and the population interfered for each station

Example on transmitter 4:

• Display the best server

• Calculate the population covered on the value corresponding to the transmitter’s number (4 in the example)

Tx4 best server coverage

Population covered

2 083 068



Exercise 1: Analysis of analog network versus analog network g. Site by site analysis - example

• Display the interference map

• Calculate the population covered on the value 255 (interference value)

Tx4 interferences

Tx4 best server coverage

Tx4 real coverage

Population covered

83 885

2 083 068

1 999 185



Exercise 2: Analysis of digital network versus analog network

a. Creation of a digital network

Duplicate the “key” analog stations (high power sites):

• Station 1

• Station 4

• Station 5

• Reduce the power of 7dB.

• Modify the coverage



Exercise 2: Digital network versus analog network b. Definition of the digital parameters



Exercise 2: Digital network versus analog network c. Summary of the digital network

Name

PADANG PAUH

GUNUNG JERAI

BUKIT LARUT

Longitude X Latitude Y Code

100.13000

100.26120

100.48210

6.29000

5.47160

4.51290

4DMS

4DMS

4DMS

Power (W)

8380

51870

1250

Ant H (m)

122.00

137.00

30.00



Exercise 2: Digital network versus analog network d. First automated frequency assignment (1/3)

• Isolate the digital stations (the analog stations

(deactivated) will be taking in account for the assignment)

• Launch the frequency assignment tool:




• Define the frequencies to assign (List assignment mode)

Channel

40

41

42

43

Analog frequency

623.25

631.25

639.25

647.25

Digital frequency

626

634

642

650

• Define the assignment method: in the exhaustive method all the combinations are checked, the one with the less interferences is selected




Define the protection ratios

Check the interference distance

Finally check:

• Threshold

• Rx antenna discriminations

• Other assignment rules…

• The frequency is automatically updated in the station parameters

• We modify the channel manually



Exercise 2: Digital network versus analog network e. Result of the frequency assignment



Exercise 2: Digital network versus analog network f. Calculate the interferences without taking into account the interferences analog vs analog

• Activate the analog network

• Deactivate the digital network

• Check the option “Activated Wanted Station”

(interferences Analog Vs Analog are not taken into account)

Analog network interferences


152 759 1203



Exercise 2: Digital network versus analog network f. Calculate the interferences by taking into account the interferences analog vs analog



• Check the option “activated + deactivated” (interferences analog vs analog and interferences digital vs analog are taken into account )





Exercise 2: Digital network versus analog network f. Calculate the interferences by taking into account the interferences analog vs analog

Current situation (analog/analog)

Planned situation (digital/analog)

Difference

Population interfered

424 039

832 216

408177

=> Launch the assignment calculation again with an additional channel



Exercise 2: Digital network versus analog network g. Second automatic frequency assignment

• Add a new channel in the frequency list

Digital Channel

39

Frequency

618.00



Exercise 2: Digital network versus analog network h. Calculate the interferences without taking into account the interferences analog vs analog



• Check the option “activated wanted station”

Analog network interferences


18 456 56

Interferences are very low



Exercise 2: Digital network versus analog network h. Calculate the interferences by taking into account the interferences analog vs analog



• Check the option “Activated + Deactivated”



Current situation (analog/analog)

Planned situation (digital/analog)

Difference

Population interfered

424 039

514 719

90 680



Exercise 2: analog network versus digital network

a. Set the network

• Activate the digital network

• Deactivate the analog network

• Check the option “Activated + Deactivated” to take in consideration the interferences Digital Vs Digital in addition of the interferences Analog Vs Digital

(Even if MFN interferences between the digital network itself are very low)




b. Calculate the interferences

Digital network interferences


909 217

Interferences are very low




c. Analyze the results

Interferences of a digital network over an analog network are stronger than the interferences of the an analog network over a digital network

Analog station (N°1) as wanted and digital station (N°9) as unwanted: the protection ratio to apply is 40

Digital station (N°9) as wanted and analog station (N°1) as unwanted: the protection ratio to apply is 3


C/I Mode – Global interference mode

We consider that the analog network broadcast the different programs

Same exercise with the global interference mode


C/I Mode – Network ID mode

We consider that in the analog network, one program is broadcasted by a group of stations, and another program is broadcasted by another group of stations

• Define the program broadcasted by each transmitter.

• Fill the field “Network ID” in the station parameters:


C/I Mode – Network ID mode

Same exercise with the Network ID mode, considering the following elements

Station #

1

2

3

4

5

6

Program

Program1

Program1

Program1

Program1

Program2

Program2

Interference analysis

MFN network analysis with ICS telecom

C/I Mode – launch the function

Exercise 1: analysis of analog network versus analog network a. Set the network

Exercise 2: Analysis of digital network versus analog network

a. Set the network

b. Calculate the interferences

c. Analyze the results

C/I Mode – Global interference mode

C/I Mode – Network ID mode

C/I Mode – Network ID mode

Related documents

Products

Support

Interference analysis

MFN network analysis with ICS telecom

C/I Mode – launch the function

Exercise 1: analysis of analog network versus analog network a. Set the network

Exercise 2: Analysis of digital network versus analog network

a. Set the network

b. Calculate the interferences

c. Analyze the results

C/I Mode – Global interference mode

C/I Mode – Network ID mode

C/I Mode – Network ID mode

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