- This topic has 30 replies, 1 voice, and was last updated 7 years, 10 months ago by Gailan Bakr.
15th December 2010 at 11:42 #52230New ManGuest
i faced this problem before.
and i plotted the problomatic cells on mapinfo with different color than the else.
so this will show us the interference sourece. and i’m sure it’s external source coz internal can’t cause this high rate of ICM band.
Regards14th October 2011 at 11:55 #52231HarishGuest
I wanna know the ICM Band details 1 to 5. Is it only escalate interference?
plz give me data15th October 2011 at 08:31 #52232pixGuest
yes, it only shows how much noise (=interference) is received on the specific frequency of the TRX.
pix25th October 2012 at 02:24 #52233xyplunkGuest
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..
🙂26th October 2012 at 20:19 #52234pixGuest
hi & welcome e/ man !25th March 2013 at 07:12 #52235Daud MohttatGuest
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.7th October 2013 at 07:21 #52236Daoud YaqubiGuest
Dear Mohttat ,
in Ericsson Technology ICMBAND is messuring the uplink interference and how to measure the uplink interference on the ground is not possible wiht the DT Tool , only by the spectrum analyzer . As experienced the external interference is in 2 type, DL & UL .
DL interference is causing by the BCCH either home Network or other Operators and UL interference is causing by Jammers .
Action Point :
For the DL interfernce change the BCCH for the home NW or neighbor operators .
For UL interference , conslut wiht the ATRA to support you for stopping the Jammers source or shift your freqquency type from 900 to 1800 or from 1800 to 900 whatever is pinging you .
Yaqubi9th October 2013 at 14:02 #52237OptimustronGuest
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,12th January 2014 at 15:56 #52238FercelleGuest
Please help!!how to fix ICM Band High in 2g…ERICSON BSC…thanks15th January 2014 at 18:23 #52239LemaureGuest
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 low16th January 2014 at 19:26 #52240pixGuest
You said :
“- 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).”
Do you have any method to differenciate each possible cause ?
also, the bad-functionning TRU.We are using MCTR, 1 MCTR per cell, with two channel groups (0 and 1)
chgr 0 = 1 bcch freq
chgr 1 = n DCHNO (SFH 1×1)
Is there any way to know whether the interference is on BCCH freq, DCHNO or both ? How to troubleshoot that ?
There is no counter per chgr, as far as i know.
If there’s a way, even a difficult one (reconfiguring the chgr for example), please let me know.
pix16th January 2014 at 19:58 #52241LemaureGuest
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//17th January 2014 at 19:08 #52242pixGuest
Thanks for the detailed answer, it’s valuable 😉
Let’s go back to the swap of MCTR among two sectors : it requires an on-site visit, doesn’t it ?
We could swap the bcch frequencies, remotely
Using SFH1x1, I agree that RLF is a big issue, but in such case I would detect neighbour sites with poor ICM too.
Actually, another possible issue…
I just found out today that this sector is actually a donor antenna to a small indoor repeater-cell. I’m pretty sure the indoor signal distribution is degraded, and it generates UL interferences.
We had literally hundreds of similar cases in 3G (especially with optical active distribution), where UL RSSI is degraded because of that.
I do have another cell with no repeater, so i’ll try the bcch swap there 😉
Will keep you posted.
Regards,18th January 2014 at 11:41 #52243LemaureGuest
thanks!13th March 2014 at 07:20 #52244BharanitharanGuest
UL interference high in NW