- This topic has 13 replies, 1 voice, and was last updated 10 years, 3 months ago by pix.
25th February 2009 at 14:02 #56007BobGuest
I have question about interference in what RX level the system consider this level is interference or noise.25th February 2009 at 18:10 #56008PixGuest
Noise is below -110dBm, INterference is above.
A signal is interfered if it is just 12dB above the interferer RxLev.
If it’s less than 12dB above, then interfered
If it’s more than 12dB, it’s clean.
(12dB is a value that works for TCH channels, on the BCCH frequency)
Use 9dB for non BCCH TRX
Use 15dB for GPRS (approx)
Use 20dB for EGPRS (approx)26th February 2009 at 08:12 #56009BobGuest
Thank you for your support one more question what will be if the TCH is not on BCCH frequency.26th February 2009 at 09:37 #56010PhanthomGuest
Why just above interferer 9 dB above interferer RxLev for BCCH ? while just 12 dB for TCH
As I knew BCCH ‘s more important channel than TCH ?
Thank a lot26th February 2009 at 11:10 #56011PixGuest
12dB for the BCCH TRX
9dB for a non-BCCH TRX.
Those are mean values used for planning.
I don’t really understand your questions. Let’s say that for voice, the voice quality in EFR is degraded when C/I < 9dB, whichever the TRX. But the TRX that carries the BCCH is more sensitive, so it is recommended to ensure the C/I never goes < 12dB.27th February 2009 at 04:29 #56012PhantomGuest
Thank you so much Pix for more clear, you ‘r realy expert ,you can clear many confuses of us -_-27th February 2009 at 06:25 #56013PixGuest
I’m like bleach… i make things clearer 🙂27th February 2009 at 06:55 #56014PhantomGuest
Pix Do you know about interference Band (Band 1- Band 5)? In Alcatel BS How does BS measure it? I found often it does not come from signal interference but from TRE or Combiner (HW)instead27th February 2009 at 18:44 #56015PixGuest
yes i know those bands.
it’s just the average rxlev of the signal received in UL by the BTS while there is no MS on it. It means it’s the level of “I” (interference) on the frequency of the TRX.
A HW problem (in ANC or in TRX) might lead to a leaking of signal into the Rx path, so the TRX believes there is a lot of noise, while actually the TRX is self-generating noise.
Man, that does sound a lot like my wife :))
Usually though, a bad value in the bands mean there is interference. Not a HW problem (but that’s possible too)2nd March 2009 at 02:58 #56016PhantomGuest
Many Thanks Pix , a big sound like my wifes also ,Pix ha..ha..21st July 2010 at 08:42 #56017PhantomGuest
Hello again , can we measure Interference Band on OMC-R or from PM counter or any for TRX level, BSS Alcalte B10
Thank you.21st July 2010 at 09:45 #56018pixGuest
only per cell :
“Average number of free TCH and free dynamic SDCCH/8 radio timeslots belonging to the interference band i”
pix21st July 2010 at 11:00 #56019PhantomGuest
Could you share any idea ? if I would like to know what’s frequency interfered me on DL by using OMC(counters,indicators) without RMS tool and if drive test is the last way
I’m trying to correct a cell facing dropcall caused of dl quality (DL Qual HO>30%) .I’ve checked HW found OK! and so many times freq I changed both BCCH and TCH
Thanks in advance.21st July 2010 at 11:43 #56020pixGuest
the DL interference can be found easily by checking your frequency planning on a map.
the idle band measurements are only about the UL interference !
since you already changed the frequencies many times, I suggest the problem is not interference 🙂 when changing frequencies, do you see any change in the ratio of HO DL QUAL ?
Don’t you think it could be a Coverage issue ? Bad RXLEV in an urban area is usually linked to a bad RXQUAL. The HO QUAL might be triggered before the HO LEV. What is the ratio of HO LEV (UL & DL) ? What is the ratio of PBGT HO ?
What is your TCH allocation efficiency per TRX ?
What are the HO Success Rate per neighbour ? (type 180, per adjacency, not per cell)
What is the TCH Erlang per TRX ? Try increase the TRX PREF MARK (from 0 to 1 for example) on the TRX that carry the smallest amount of Erlangs, and oppositely, decrease the TRX PREF MARK of the TRX that carries the highest amount of TCH Erlang.