ICM Band

Dear,

I wanna know the ICM Band details 1 to 5. Is it only escalate interference?

plz give me data

ERICSSON:
If ICM is high (2-5), try to see if the affected freq are on BCCH TRX or TCH TRX.
Also, check for drop reasons.
Then, compare with the ICM readings.
It would tell if the ICM is on BCCH as it would show on the reasons as Bad Quality Downlink.
If it is on a TCH, it would show as Bad Quality Uplink.

Change the affected frequency.
record FAS to find out what clean frequencies you could use..

🙂

dears
we are using PGSM as an BCCH nd TCH and EGSM as a TCH in different CHGR. now we have very high ICM almost in uplink. does andy body has experince for reducing the ICM in UL channel? we tried to halt the EGSM, but no result. even we tried to put BCCH from EGSM but no good efficiency.
please share your idea.

Daud Mohttat
First thing, you need to establish the following:
1. What is your spectrum range?
2. What are your near spectrum neighbors?
3. There are different kinds of spectrum usage in your country?, i.e., your country use rules of America and Europe at the same time or only one?
4. There is an inventory of spectrum usage in your country?
5. Did you make a spectrum sweep before you put in service your system?
Why I asking you about that? Well because in our country some things like I mentioned before are happening, we have 800 Mhz cellular system and 900 Mhz too, this is bad because one operators is using P-GSM and it overlaps by 4 Mhz the 800 Mhz, then P-GSM was suffering and they think that we were having intermodulation or harmonic components, but the real thing was that because the filters of BTS are standard they receive our downlink power into its uplink, in other words, the filter of P-GSM for uplink is from 890 Mhz up to 915 Mhz then they receive the full power of any BCCH in the range of 890 Mhz to 894 Mhz. The case is worst if you use E-GSM this is from 880 Mhz to 915 Mhz and R-GSM is from 876 Mhz to 915 Mhz.
By the way in America the 900 Mhz is an ISM band then we have a lot of devices like cordless phones, toys, automatic gates, etc.
If you don’t have spectrum conflicts and the less likely situation about interference from ISM, because your country would need to have many devices of that kind and working at the same time or almost all the time, then the most likely is you are facing a JAMMER with high power located in the worst location, for example a hill in the middle of a valley, or less probably but not impossible maybe a very powerful broadcast transmitter, like TV, FM, we face that problem in the past with a broadcast from TV that have a broken filter.
You need to take hands on spectrum analyzer and see you worst locations at the time you are have the worst situation in order to have a great opportunity of catch the interference and please don’t see only you spectrum see below and above because you will get more chances of catch it.
I hope this can help you, best regards,

Hi!

which hopping type are you using?
If it’s NH RH with 1×1 or 1×3 pattern you may be facing overshooting cells in your network. if not it’s likely to be:
– a bad functionning of TRU: can be troubleshooted if the bad ICM is the same on all the sectors of the same site
– internal/external interferences (optimize your frequency if internal or deal with the regulatory board for external cases).

also check if the threshold set on the parameter ICM interfband1..5 is not to low

Hi Pix!

to troubleshoot you can swap the MCTRX with this of a cell having no issue and you’d be able to conclude if the MCTRX was having a problem or not.
if the test is not relevant because the problem stays on the first cell, you can then check if the cells on the whole site are having the same problem.
YES: Check VSWR to have the status of your feeders, connectors, antenna, Diplexer, …
NO: an interference.
with a drive test kit or with a spectrum analyser you’d be able to distinguish and internal or external interference.
if its an internal interference:
– on the BCCH: it should be changed
– on the MALISt, compute the Real Load factor RLF of this cell and analyse it’s TA.
* if RLF>40% create a 3rd CHGR and add fixed frequencies from the BCCH (it would help to reduce the RLF)
* otherwise (also true for high TA) you need to reduce the coverage of the cell (this last case is the most spread)

BR//

I agree.
thanks!