Interference in Radiocommunication Systems
1
Prepared by :
Eng.Yasir Mohammed Bashar
Yasir_192@ntc.gov.sd
Interference calculations
Outlines
•
Interference definition/types
•
Interference analysis
•
Interference calculation using
SMS4DC
Interference definition(ITU)
The effect of unwanted energy due to one or a
combination of emissions, radiations, or inductions
upon reception in a radiocommunication system,
manifested by any performance degradation,
misinterpretation, or loss of information which could
be extracted in the absence of such unwanted energy.
Power sources (50 Hz):
due to leakage, arcing neon signs (continual arc)
fluorescent light fixtures.
Co-channel:
same frequency various power levels - strongest signal captures
receiver.
Adjacent Channel
: is interference caused by extraneous power from a signal in
an adjacent channel. ACI may be caused by inadequate filtering
Intermodulation:
unrelated frequency mixes with another signal generating a
signal on or close to the receive frequency.
Harmonic signals
are usually unwanted signals which are exact multiples of the
operating frequency.
Out of band emissions
Out-of-band emission is emission on a frequency or
frequencies immediately outside the necessary bandwidth which results from the
modulation process.
Types of interference
Protection ratio,
PR
The required difference in dB between the level of the wanted signal
and the level of the interfering signal to achieve the required quality
of reception.
Minimum field strength (C/N)(db)
It is a minimum field strength level which is necessary to fulfil the
signal quality for coverage.
Waned field strength (
Ew
)
The required field strength of a wanted signal to achieve the required
quality of reception, considering multiple interfering signals and their
corresponding protection ratios .
Ew>En
Nuisance field strength( En)
The equivalent required field strength of a wanted signal to achieve
the required quality of reception, considering a single interfering
signal and its corresponding protection ratio.
En= Ei(interference field strength)+ PR
Important parameters
Interference by Noise
Wanted
field strength Ew
Minimum
field strength Emin
Noise level Es
C/N
Noise
wanted TX
Criteria for coverage
Wanted Field Str. > Minimum Field Str.
E
w
>
E
s
+
C
/
N
Coverage area
E
m
i
n
Interference by one Transmitter
Nuisance field En
Wanted
field strength Ew
Protection ratio
Interfering
field strength Ei
C/N
Noise
Coverage area
with noise only
Criteria for coverage
Wanted Field Str. > Nuisance Field Str.
E
w
>
E
i
+
P
R
Coverage area
E
n
with one
interfering Tx
Interference by several Transmitters
Usable field strength
Eu
E
i
2
Protection ratio
Ew
E
i
1
C/N
Noise
Coverage area
with noise only
Criteria for coverage
Wanted Field Str. > Usable Field Str.
m
Ew
>
E
n
Σ
j
Coverage area
1
=
j
123
with several
interfering Tx
Eu
BC - BC (FM sound broadcasting stations):
Is to calculate aggregated interference level of
interferer BC stations on a directional receiver of
wanted BC station.
By selecting of BC2BC item the list of all FM sound
broadcasting station is presented as in figure 1.1 below.
After selecting a wanted bc station Dialog box of
Interference Parameters is opened to set search
conditions for victim BC stations figure 1.2.
Sound broadcasting station
Spreadsheet of all available FM sound broadcasting stations in database
Interference calculation parameters
Spreadsheet of found interferer BC stations
Result:Coverage area with/without interference of a concerned BC station
BT2BT
: Item to calculate aggregated interference level of
interferer BT stations on a receiver of wanted BT station, The
procedure of BT to BT interference calculation is same as BC
to BC.
TV broadcasting station
Spreadsheet of all available FM sound broadcasting stations in database
Interference calculation parameters
Spreadsheet of found interferer BT stations
Result: Coverage area with/without interference of a concerned BT station
Coverage area of a concerned TV station in presence of /without interferer stations
Usable field strength on receivers of wanted TV broadcasting station inside a selected area
FX2FX (link): Item to calculate interference of stations of
different point – to – point hops on each other by consideration
antenna radiation patterns and XPD in accordance with ITU-R
P.452 recommendation. This item contains two sub-items
“Interference to” and “Interference from” enabling user to
calculate the caused interference by wanted hop transmitter on
receivers of other hops or the caused interference of other hops
transmitter on wanted hop receiver, respectively.
Choosing one
of the sub items under this item opens the spreadsheet of
available links, then by selecting one of the wanted link an set
the parameters and by finalizing interferer (or victim) link
selection. Then the calculation result is displayed including
The wanted hop information and interference calculation
results.
Point 2 point Links interference
Point 2 point communications
The spreadsheet all available links
Set Parameter dialog box and Hops meeting relevant conditions
Interference occurrence is highlighted by red text background
FX2FX (station): Item to calculate interference of fixed
stations on each other in accordance with ITU-R P.452
recommendation. This item contains two sub-items
“Interference to” and “Interference from” by choosing one of
the sub items under this item opens the spreadsheet of available
fixed stations. Then select one of the stations and set the
parameters and by finalizing interferer (or victim) link
selection. Then the calculation result is displayed including
The wanted hop information and interference calculation
results
Fixed stations interference
List of available fixed stations
Set Parameter dialog box and fixed stations meeting relevant conditions
Dialog box of interference of wanted fixed TX on victim fixed receiver
The item “FXM” in “Interference” menu implemented for
calculation of interference produced/experienced by stations in
land mobile service (any frequency) and fixed service (below
1GHz) on each other.FXM consist of the following subitems:
•
Interference to (Free Space and P.1546)
•
Interference from (Free Space and P.1546)
Interference from fixed station to mobile station and vice versa
List of fixed (below 1GHz), and land mobile base stations
Set Parameter dialog box for setting searching condition and
Spreadsheet list of found fixed, base and mobile stations using
free space propagation model
Result of interference calculation of wanted TX on victim RXs using free space
propagation model
P1546 propagation model parameters and result of interference calculation of
wanted TX on victim RXs (below 1GHz)
Spectrum Management Database Interface - SMDI
LS telcom
thalys
Workflow of measurement request
Spectrum Monitoring
System
Spectrum Management
System
Measurement Request
Data packet, data stream
1.
Take over
Request
2.
Set Devices
3.
Measure
automatic / interactive
4.
Evaluate Results
5.
Create Report
(automatic)
Measurement Result
Data packet
1.
Create
Measurement
Request
2.
Send Request
3.
Receive Result
4.
Evaluate
Results
(automatic)
Interface
Workflow of data request
Spectrum Monitoring
System
Spectrum Management
System
Data Request
Data packet
1.
Create Request
(Frequency List,
Transmitter List License
Data)
2.
Receive Report
3.
Evaluate Report
(automatic)
Data Report
Data packet
1.
Take over
Request
2.
Collect requested
data
3.
Create Report
4.
Send Report
(automatic)
Interface
Argus - SMDI
ORM - parameters
45
Results-(Argus)
46
Result :bearing (Argus)
49
EXCERSISES
National Telecommunication Corporation (NTC), SMS4DC work Shop, Khartoum – June 2012
Interference calculations and definitions in radiocommunication systems are crucial for maintaining signal quality. This content explains various types of interference, such as co-channel and adjacent channel interference, and important parameters like Protection Ratio. It also covers the effect of unwanted energy on reception and how different sources of interference can impact communication systems.
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Presentation Transcript
Interference calculations Prepared by : Eng.Yasir Mohammed Bashar Yasir_192@ntc.gov.sd 2
Outlines Interference definition/types Interference analysis Interference calculation using SMS4DC
Interference definition/types 4
Interference definition(ITU) The effect of unwanted energy due to one or a combination of emissions, radiations, or inductions upon reception in a radiocommunication system, manifested by any performance degradation, misinterpretation, or loss of information which could be extracted in the absence of such unwanted energy.
Types of interference Power sources (50 Hz): due to leakage, arcing neon signs (continual arc) fluorescent light fixtures. Co-channel: same frequency various power levels - strongest signal captures receiver. Adjacent Channel: is interference caused by extraneous power from a signal in an adjacent channel. ACI may be caused by inadequate filtering Intermodulation: unrelated frequency mixes with another signal generating a signal on or close to the receive frequency. Harmonic signals are usually unwanted signals which are exact multiples of the operating frequency. Out of band emissions Out-of-band emission is emission on a frequency or frequencies immediately outside the necessary bandwidth which results from the modulation process.
Interference analysis 7
Important parameters Protection ratio, PR The required difference in dB between the level of the wanted signal and the level of the interfering signal to achieve the required quality of reception. Minimum field strength (C/N)(db) It is a minimum field strength level which is necessary to fulfil the signal quality for coverage. Waned field strength (Ew) The required field strength of a wanted signal to achieve the required quality of reception, considering multiple interfering signals and their corresponding protection ratios .Ew>En Nuisance field strength( En) The equivalent required field strength of a wanted signal to achieve the required quality of reception, considering a single interfering signal and its corresponding protection ratio. En= Ei(interference field strength)+ PR
Interference by Noise Wanted field strength Ew Minimum field strength Emin Noise level Es C/N Noise wanted TX Criteria for coverage Wanted Field Str. > Minimum Field Str. Ew > Es + C/N Coverage area Emin
Interference by one Transmitter Nuisance field En Wanted field strength Ew Protection ratio Interfering field strength Ei C/N Noise Coverage area with noise only Criteria for coverage Wanted Field Str. > Nuisance Field Str. Ew > Ei + PR En Coverage area with one interfering Tx
Interference by several Transmitters Usable field strength Eu Protection ratio Ew E i 2 E i 1 C/N Noise Coverage area with noise only Criteria for coverage Wanted Field Str. > Usable Field Str. m En j Ew > Coverage area with several interfering Tx 1=j Eu
Interference calculation using SMS4DC 12
Sound broadcasting station BC - BC (FM sound broadcasting stations): Is to calculate aggregated interference level of interferer BC stations on a directional receiver of wanted BC station. By selecting of BC2BC item the list of all FM sound broadcasting station is presented as in figure 1.1 below. After selecting a wanted bc station Dialog box of Interference Parameters is opened to set search conditions for victim BC stations figure 1.2.
Spreadsheet of all available FM sound broadcasting stations in database
Result:Coverage area with/without interference of a concerned BC station
TV broadcasting station BT2BT: Item to calculate aggregated interference level of interferer BT stations on a receiver of wanted BT station, The procedure of BT to BT interference calculation is same as BC to BC.
Spreadsheet of all available FM sound broadcasting stations in database
Result: Coverage area with/without interference of a concerned BT station
Coverage area of a concerned TV station in presence of /without interferer stations
Usable field strength on receivers of wanted TV broadcasting station inside a selected area
Point 2 point Links interference FX2FX (link): Item to calculate interference of stations of different point to point hops on each other by consideration antenna radiation patterns and XPD in accordance with ITU-R P.452 recommendation. This item contains two sub-items Interference to and Interference from enabling user to calculate the caused interference by wanted hop transmitter on receivers of other hops or the caused interference of other hops transmitter on wanted hop receiver, respectively. Choosing one of the sub items under this item opens the spreadsheet of available links, then by selecting one of the wanted link an set the parameters and by finalizing interferer (or victim) link selection. Then the calculation result is displayed including The wanted hop information and interference calculation results.
Set Parameter dialog box and Hops meeting relevant conditions
Interference occurrence is highlighted by red text background
Fixed stations interference FX2FX (station): Item to calculate interference of fixed stations on each other in accordance with ITU-R P.452 recommendation. This item Interferenceto and Interferencefrom by choosing one of the sub items under this item opens the spreadsheet of available fixed stations. Then select one of the stations and set the parameters and by finalizing interferer (or victim) link selection. Then the calculation result is displayed including The wanted hop information and interference calculation results contains two sub-items
Set Parameter dialog box and fixed stations meeting relevant conditions
Dialog box of interference of wanted fixed TX on victim fixed receiver
Interference from fixed station to mobile station and vice versa The item FXM in Interference menu implemented for calculation of interference produced/experienced by stations in land mobile service (any frequency) and fixed service (below 1GHz) on each other.FXM consist of the following subitems: Interference to (Free Space and P.1546) Interference from (Free Space and P.1546)
Set Parameter dialog box for setting searching condition and Spreadsheet list of found fixed, base and mobile stations using free space propagation model
Result of interference calculation of wanted TX on victim RXs using free space propagation model
P1546 propagation model parameters and result of interference calculation of wanted TX on victim RXs (below 1GHz)
Interface to monitoring systems 40
Spectrum Management Database Interface - SMDI thalys LS telcom
Workflow of measurement request Interface Spectrum Management System 1. Create Measurement Request Spectrum Monitoring System Measurement Request 1. Take over Request Data packet 2. Set Devices 2. Send Request 3. Measure automatic / interactive 4. Evaluate Results Data packet, data stream 5. Create Report 3. Receive Result (automatic) 4. Evaluate Results Measurement Result (automatic)
Workflow of data request Interface Spectrum Management System Spectrum Monitoring System Data Request 1. Take over Request 1. Create Request (Frequency List, Transmitter List License Data) Data packet 2. Collect requested data 3. Create Report Data packet 2. Receive Report 4. Send Report Data Report 3. Evaluate Report (automatic) (automatic)
