Uplink Interference - Kindly Show Me The Light...

[MyVi78]

Greeting fellow members,

Today is the first time I've heard about ICM band and though I have no idea what it means, all I can guess is it's about uplink interference.

I'd be hoping some members here could decribe what ICM band is, how does it look like and what should we be looking at if it's about uplink interference.

Can the interference be external/internal from different UEs/both?

[Evghenii]

Yes, You're right it's about uplink interference. ICM stands for Idle Channel Measurements. They are periodically performed during the Idle frames. You can find all the needed information following the link:
ftp://ftp.vanwinkle.org/Rene/Uplink%20Interference.pdf

[melkaiy]

ICM is "Idle Channel Measurement". It measures uplink interference while TCH or SDCCH is idle. There are 5 ICM band due to the interference level. The worst one is the 5th one, the best one is the first.

In addition to this the TS are placed in various ICM bands on basis of data for quality collected in the last 5 calls (may vary as per vendors but this is a standard) on that TS. If there is any call drop observed in the last 5 calls history due to quality issues the TS is placed in one poorer ICM band.

Check the interference levels (DL & UL) and TA.

If there is a rise in poor DL/UL quality post swap then there is a chance that the new equipment is radiating more power (usually old equipment's power reduces-e.g. it shows 43dBm but actually its less due to old equipment or antenna fault).
The same results in increase of interference regions as due to increase of power the area of overlap regions increase and thus more calls face interference in comparison to last scenario so eventually the TS record poorer quality bins in last 5 calls and thus more number of TS are mapped to poorer ICM bands.

if this one helps please add repz :)

[melkaiy]

one more thing.. ICM is also defined the Industrial, medical and scientific band which ranges from 866-870 MHz. If your network is interfered then the external interference could be in this range. You can perform band scan using spectrum analyzer.. during band scanning you don't need to position the horn antenna in horizontal when doing stationary test because we all know that cellular antenna' polarization is usually cross polarized and some might still vertical.


please add rep if this one helps :)