- This topic has 76 replies, 1 voice, and was last updated 9 years, 10 months ago by IAN.
9th May 2011 at 12:45 #59903bjushkaGuest
thanks Pix, even I dont like deactivating intracell HO interference,,, it looks like we are hiding problems that we can have in the network,,, not sure!!!
Still I don’t understand why HO due to interference are high and quality in DL is bad when intracell HO is activated?! We have even used fix ARFCNs in a small area but nothing changed so it is more a problem between AMR and intracell HO interefence, I think! 🙁
Ian, we are using SFH 1×1, but we have test even 1×3 and didn’t have any change in network.
.bjushka.9th May 2011 at 16:50 #59904pixGuest
i don’t recall any problem between AMR and HO Interference. I’ll check it out…
There are specific parameters for AMR calls for HO cause Quality and cause Interference, such as l_rxqual_dl_AMR, just ensure they are all tuned “correctly”.10th May 2011 at 07:11 #59905SmartGuest
AMR is just a coding scheme so its not responsible for your drops. You just need to set AMR parameters according to your needs.
Deactivating Intracell HO its not hiding your problems but resolving them.10th May 2011 at 07:58 #59906pixGuest
smart > i agree with you, but it’s a good opportunity to find why these things are not working. Then later, he’ll disable it anyway 🙂
bjushka > in your “zone”, what are your settings for:
pix13th May 2011 at 16:27 #59907bjushkaGuest
Sorry for the late replay,,,
I am happy to discuss the problem by analyzing it!
In our network we are using Nokia technology, so I am not sure what really mean the above parameters:
any way, the intracell HO interference DL/UL is enabled, intracell HO is enabled for AMR and FR and we are using only AMR FR. About TFO I dont know if we are using that, i will inform you.
bjushka13th May 2011 at 23:43 #59908IanGuest
What would you recommand for these parameters with SFH, what we have here is :
L_RXQUAL_DL_H 39 *0.1
Since we activated SFH 1*1, we get a lot of UPLINK QUAL HO, i dont know why, you might help.
ian14th May 2011 at 02:20 #59909IanGuest
One basic question,
Do we need to RESET the BTS when going BBH to SFH ?
Looks like they did not perform this here …might create problems ?
IAn14th May 2011 at 18:51 #59910pixGuest
the settings “l_rxqual_dl_h” is the threshold above which the rxqual is considered too bad, for non-amr calls, so a ho cause quality DL is triggered.
l_rxqual_dl_h_amr is the equivalent threshold for quality HO, but for amr calls only, this time. Anyway since you are working with nokia, you should check with them and open a support ticket on this issue ?
perhaps you’re seeing real ul interference ? SFH might have increased your UL interference in your network?
have you checked “idle” interference band measurements ?
i don’t recall you have to reset the bts to enable sfh. I’m almost certain it is not needed. why would you think so ?
a cell in which you change frequency or hopping mode will reset anyway : it will go down and reset itself to apply the change.
pix16th May 2011 at 18:10 #59911IanGuest
Yes, you are aright , i think the SFH raised UL interference but some sites are showing 25% of UL Quality, is there a way to reduce this interference, we already activated UL PQWRCTRL + DTX UL.
it also raised DL quality but i noticed ALU very sensitive to adjacent channels.
As per the BTS, i’ll ask OMC-R guy who set up SFH.13th June 2011 at 15:39 #59912SuzaneGuest
Hi Pix, This was an intresting discussion,
I want to know following things:
1)I have increased my DL & UL HO Qual Ths. from 39 to 55, After changes Qual HO are reduced but no changes in KPI’s(Handover success/DL Quality)remains same- I want to know if reducing Quality Handover is good or the cells where Quality is bad it should be triggered earlier?
2)In My network If i see HO distribution,60% HO is due to PBGT,20% due to DL Qual & 19% approx is DL/UL interference.-Kindly help how to reduce these Quality/Interference HO, will it help in improving KPI’s13th June 2011 at 18:48 #59913pixGuest
1/ it’s hard to say… it looks like your network is quite clean, interference-wise, so by changing the HO Qual threshold, you will merely reduce the number of HO, while the voice quality remains ok.
As you said, what you did didn’t change much the KPIs. But reducing the number of HO is a good thing. In a way, you did improve one KPI that you were not monitoring (the number of HO).
The only thing you must ensure is that the voice quality is not degraded.
2/ The best way to reduce interference is to locally modify your frequency planning, then use AMR, power control, dtx, etc.
changing the ho thresholds is just hiding the problem, which will sooner or later re-appear.
pix14th June 2011 at 16:58 #59914SuzaneGuest
Yes you were right,changing threshold is hiding problem but though there is no increase degradation in RxQual.
Secondaly, We are Using AMR FR & AMR HR, Power Control is also enabled in both UL & DL & Frequency Plan is based on Optimised plan from a tool Output based on sig strenth & measuring BCCH’s.
This Bad DL Quality scenario is across all the network. e have done lot of Physical Optimization & overshooting but still DL Rx Qual is below 95%(0to5/0to7)samples.
Can you suggest what need to be checked further. Also i suspect following, please suggest :
1.Disabling AMR(can there be AMR issue)??
2.Can DTM effect in RxQual DL??
3.Can there be a difference in RxQual Sub & Full…do u have any instances where after Disabling DTX, We can see improved RxQuality??14th June 2011 at 18:04 #59915pixGuest
1, 2 and 3/ -> no
in order to increase the %samples > rxqual 5, then you should actually keep your ho qual threshold at 4 or 4.5. If you put it to 5.5, then you’ll have more samples at rxqual > 5.
Anyway, that’s probably not the are we shuold be tuning right now, regarding your target.
AMR would increase the voice quality, but the rxqual stays identical.
Have you tried making your power control more aggressive ? Thanks to PC Thresholds : try to reduce the DL and UL tx powers in order to avoid interfering neighbours.
downtilt and azimth is a good approach. What is your average downtilt ?
Are you using electrical downtilt ? If you are using mechanical, then the benefits on interference are not so interesting : the backlobe and sidelobes are not downtilted !
Only the electrical tilt provides a good way to reduce intereference.
when doing drive-test, can you detect where are the interference coming from ? Try to work on a specific case, see if more downtilt or better PC would work. Also, think about using antennas with a vertical bandwidth which is narrower.
good luck 🙂
pix15th June 2011 at 12:55 #59916SuzaneGuest
Hi Pix, Thanks for clearing those doubts…
1.If if you say PC more aggressive then i must say i am using following settings:
We are using 900 Band:
MAX power level of MS=5
MIN power level of MS=16
MIN power level of BS=10(where 0:Pn,1: Pn-2 dB;15:Pn-30 dB & Pn=The maximum power level of BTS is Pn)
Increase uplink level=25 (Ths 0-63 mapped with -110 to-47)dBm
Decrease uplink level=35
Increase uplink quality=4
Decrease uplink quality=1
Increase downlink level=20
Decrease downlink level=35
Increase downlink quality=4
Decrease downlink quality=1
where P/N for all UL/DL is 2/3
Also Handover MarginRxQual is =6dB
We have tried to change these but not able to have a forward path. Please suggest some threshold based on above to see some good result in RxQuality.18th June 2011 at 13:00 #59917pixGuest
i’m willing to help, but i’m not familiar with your parameters. I think I could understand them, but I need you to help me :
(because i’m not very bright…)
could you translate all powers in dB or dBm, in your thresholds ?
thanks a lot.