Pathloss 4.0 Frequently ask

1. ) SUBJECT : INTERFERENCE CALCULATION


Question :

I never used Interference calculations before but want to try it now. What are the things to consider before I can succesfully run this feature? and What are the steps in order to do it? Thanks in advance!!

Answer : You should take into account, according to the frequency band:

1) Coordination distance and Maximum frequency separation: it means the phisical and frequency distance between interfering transmiter and victim receiver.
2) Minimum interference level and digital interference objective: It means the minimum inteference level in order that the receiver threshold of the radio does not degrade mora than one db.
3) If you want to ignore diversity antennas and adjacent channels.
All you have to do in PLIV is to use the network module where you have to have all the links you want to take into account in the analysis.

Make sure that the equipment you are using have the T/I (threshold to interference) curves so that the calculation can be performed according to TIA (Telecomunication Industry Association).

Question :

Also can you tell me, why do we use -115 db as min interference level.

does it calculates co channel or adjacent channel interference?

Answer :

We use -115 db as min interference level.

Because there is no receiver with sensitivity better than -115 db; this way you guarantee that the signal you will discard will not be effective.

It calculates co and adjacent channel interference.

And there is an option where you can ignore the adjacent channels

For distance I recommend the following:

According to Telecommunication Industry Association (TIA) of the United

States, they recommend to use a circular coordination contour with a

Larger radius sector extending 5 degrees on either side of the antenna main beam azimuth. These radii are referred to as the circular coordinancion distance (Dc) and the keyhole coordination distance (Dk). Again, Dk is +- degrees about the antenna main beam. Dc is the emaining 350 degree circle about the antenna. For interference analisys, the following circular coordination contours are to be used: Below 15 GHz: Dc = 200 km and Dk = 400 km Above 15 GHz: Dc = 75 km and Dk = 140 km.



For frequency separation I recommend to use 5 times de biggest bandwidth of the links. If you are employing radios with 28 MHz of Bandwidth, then use 140 MHz for frequency separation. I recommend this value because its enough frequency to interference analisys according to the T/I curves of the radios.



The Max frequency separation in pathloss have nothing to do with the frequency band you are using. It has to do with the adjacent T to I (threshold to interferer) curves and to see at which separation the calculation is not important because the values are very low. The purpose of putting a small value is just to save proccessing time.