ATDI Consulting ATDI · PDF fileMicrowave mode interference Calculations Point to Point only Multi point mode interference Calculations Point to Point only stations, microwave & subscribers

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Mobile Interference

Calculations in

ICS Telecom &

HTZ WarfareNovember 2010


Introduction

• This Webinar will cover:-

– What is interference

– Types of interference calculations in

ICS Telecom & HTZ Warfare

– Mobile interference calculations

– Masks

– Interference calculations with multiple

propagation models


Interference Calculation used in

ICS Telecom

• Carrier to Noise ratio (C/I)

• Threshold Impairment (TI)

• Interference to Noise ratio (I/N)


What is Interference

Thermal noise floor of receiver N (kTBF)

Receiver threshold

point

RX Noise Fig.(F)

FadeMargin

Receive level (C)

Threshold Impairment

InterferenceI

C/I ratio

Minimum

C/I ratio

Carrier to Interference C/I Threshold Impairment TI Interference to Noise ratio I/N

Thermal noise floor (kTB)

I/N


Calculating coverage for interference

calculationsTips:Make sure you predict far enough (Setting limit distance)

For Communication systems predict to noise floor or below

For Radar systems predict to at least 12dB below noise floor

Not ticked

Mechanical or electrical tilt

(not tilt and resolution from RX parameters)

Attenuation between

systems at same site


Interference calculations within

ICS Telecom & HTZ Warfare

Coverage mode interference

calculations

MFN , SFN and Radar

Microwave mode interference

Calculations Point to Point only

Multi point mode interference

Calculations Point to Point only

stations, microwave & subscribers


W-CDMA mode interference

Pilot Ec/Io and traffic & Eb/No

Subscriber interference

Calculations Point to Multi Point

and Multipoint to point only


Both these interference calculations

are based on virtual TXs or RXs

into fixed TXs or RXs


This will modify C

C= C+10LOG(activity)

STD


Masks

Image Raster

Data Raster

DEMONSTRATION


NFD• IRF Calc

Spectral Mask

Receiver Selectivity

Set up all directories

DEMONSTRATION

Priority 1

Show ATDI/BASE

Directory


Priority 2

Predefined Masks

FM Broadcast

e.g.TV Broadcast

Analogue & Digital

802.11

802.16

Some Microwave

systems

etc


Frequency

F1

B1

B2

-44dBm

-79dBm

-97 dBm Receiver Noise Floor (kTBF)

FrequencyN=0

0dB

Interference Rejection Factor

F2

20dB

40dB

N=1 N=2N=-1

-75dBm

F3

F2’

RX1

Wanted F1 Rx signal =-44dBm

Un Wanted F2 Rx signal =-79dBm

Un Wanted F2’ Rx signal =-75dBm

Un Wanted F3 Rx signal =-80dBm

-80dBm

C/I =-44 - (10^(-79/10+10LOG0.2)+

10^(-79-20/10) +10^(-75-20/10)+10^(-80-40/10)))

Overlap area, % of B1 overlapped eg. 20%

Overlap area

of F2

F2 F2’F3

Multiple Interference signals

Wanted

N=0 co-channel with Receiver

N=1 adjacent channel with receiver

Etc.

Priority 3

Assumes response curve symmetrical


Best method of checking what

interference calculations do• Produce DTM & Clutter map suitable

for checking interference calculations

on (flat earth & no clutter)

Select suitable propagation model

(free space path loss)

DEMONSTRATIONCheck what's going on with Analysis function

“A”

Change elevation code

Change clutter code


Interference Calculations

Defines C/I required

Global Interference – Pixel interfered if at least one serving site is deemed interfered

Interference+best server – Pixel interfered as global unless service available from

another site or channel

Interference on best server – Pixel interfered when C/I required on best server is

exceeded

Interference Activated + De –act. Pixel interfered if interference is deemed present

when active sites are interfered with by all other active and deactivated sites

Interference Network ID – Interference between sites with same Network ID is

excluded

Interference wanted signals- Displays the number of channels available (with no

interference)

C/I Map: Min(C/I) – C/I map assuming C is at Global threshold level (activated sites

only)

C/I map on best server – shows maximum interference to receivers connected to best

server activated stations only – multichannel

Protection margin – shows the C/I protection above wanted C/I based on best server

Protected field strength – shows the unwanted field strength in the wanted service area

where field strength is modified by required protection ratio (C/I)

Demonstration

Coverage /Network Interference/ C/I Mode


Coverage /Network Interference/ IRF Mode

Threshold Degradation – calculates the

degradation of the noise floor (Global or

RX specific)

Modifies coverage by TD of power

sum of all activated and un-activated stations

Based on each stations KTBF

C/I Calcs

Demonstration


Interference calculations using

multiple propagation models

DEMONSTRATION

•Export unwanted coverage: File / Export / Export TX

coverage to FDU files

•Load wanted coverage

•Undertake interference calculation(s)


Thank you for attending

This webinar covered most of the basic

interference calculations for mobile systems

within ICS Telecom and HTZ Warfare

Any Questions?

ATDI Limited

Kingsland Court - Three Bridges Road

Crawley - West Sussex - RH10 1HL – UK

Tel +44 (0)1293 522052 - Fax +44 (0)1293 522521

Email: [email protected]

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mailto:[email protected]

http://www.atdi.co.uk/

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Documents

ATDI Consulting ATDI · PDF fileMicrowave mode interference Calculations Point to Point only Multi point mode interference Calculations Point to Point only stations, microwave & subscribers