Increase in Interferance HOs with DTX

Good evening Pix, Sergio and 2112!

Let me join the discussion about using DTX and AMR features simultaneously 🙂

In a new version of so called *common parameters* we are recommended (=must) to use both flags:

DTX_FR_INDICATOR_AMR = Enable

DTX_HR_INDICATOR_AMR = Enable

As I see from this discussion it can be a real danger not only for KPI, but – the most important issue – for subscriber perception, i.e. for real speech quality .
To be true, I don’t understand properly what is the cause of incompatibility for these two features.. Do we have problem both with FR and HR + DTX? In 3GPP TS26.103 we found the only mention about incompatibility between ERF (12,2) and DTX, but I’m afraid we’re mistaken..
Dear Pix, could you be so kind, please, to give some more explanation about this situation (or forward us to certain document) ?

Thanks a million!
Best regards,
Lily

Hello PIX, Lily and Sergio,

just want to share our results regarding this Parameter W_Qual_HO,

We tried it for few cells with settings,

A_QUAL_HO = 6
W_QUAL_HO = 2

and result was increase in Interefrence and Quality HOs.

Explanation given to us by vendor was that averaging window becomes variable and is more reactive to transitional degradations in DL RX Quality resulting in increased Quality HOs.

I have to say that this weightage concept was really strange as we were thinking that size of averaging window will remain same and just DTX = 0 measuremnts will get twice the weightage of DTX = 1 measurements and averaging will be over 6 measurements regardless of how many were DTX or Non DTX and denominator of averaging could be modified accordingly.

Needless to say that we have reverted back to orignal settings and we are still having very high DL Interfernce HOs(around 5%) for all of our BSCs where AMR and DTX for AMR HR and FR is enabled.

Hello, Pix and 2112!

Pix,

oh, I’m sorry, I really didn’t want to embarrass you.

Next week we’ll implement recommended settings for 3 BSCs (some sort of experiment) and than we’ll make a drive-test in that area, focusing on MOS measurement. I’m looking forward to do it and see the results 🙂 …. :(((

I think it would be better to contact TAC having as much info (DT results and PM statistic at least) as we can collect, in order to have a “meaningful conversation” :)))).

Of course I’ll share results of our investigation 🙂

2112,
Thank you very much for sharing your experience, now we know for what we should be ready (changing those parameters)

And just one more question: Did you fix speech quality degradation after AMR_DTX activation (from drive-tests or subscriber’s complaints)?

Thank you in advance 🙂

Good night, 2112 and Pix!
Best regards,
Lily

:)))))

Dobroe utro 🙂

I’ll follow your wise advice. Unfortunately now we have no possibility to contact ALU TAC directly, only through our HQ operational department – it will be a little bit longer, but we have enough persistence 🙂 As soon as we get information from them I’ll share it here 🙂

Nevertheless we need practical results as an argument in order to be able to dispute the main (Moscow) HQ if they decide to activate AMR + DTX on the whole network… their motivation will be, of course, “for improving speech quality and subscriber’s perception ”…

It would be much better just to remove all flags related to AMR + DTX from OMC-R so nobody has temptation to “optimize” voice quality with them :)))))) at last until the problem will be solved …. Please..:)

…oh, I would like to spend some hours outside drive-testing, but these days I’m spending much more time in office, analyzing other people’s logs..

Have a nice day!
Best regards, Lily

Dear 2112!

Thank you very much for information.
Next week I can share our results.

Best regards,
Lily

Hi,
I am new to this Forum and googled “DTX with AMR” and landed up over here :P…Very Informative Discussion, i must say.
In my Network(Vendor Alcatel-B10), DTX(DL/UL)is totally disabled for AMR.I had heard earlier that its not advisable to implement DTX with AMR.Currently we are under a lot of pressure from customer and concentrating on improving the Call Drop Rate.So,keeping all the discussion into consideration, do u prefer enabling DTX with AMR(for CDR improvement) or should i avoid that for the risk of degradation of End user Perception + increase in Quality/Interference HO’s?
Thank you for you expert opinion.

Dear PIX,
Yeah i work for ALU(wasn’t too hard 2 guess, right :P).
Thanx for your suggestions.We have already set RadioLink TimeOut AMR and radiolinktimeout AMR_BS to max(32) as initially when we implemented AMR, it caused increase in Call Drop which got fine after changing RLT for AMR.I will try to enable it one by one as suggested by you.I have heard that its not advisable to enable DTX on HR??whats your take on that? As you know that in Alcatel we have separate set of parameters for enabling DTX for HR/FR so,if that is the case i can only enable it for FR?
Also bringing improvement in DCR by codec mode adaptation, you suggest to tune parameters in such a way as to use more robust codecs for HR/FR?

Hey pix..sorry for the late reply.actually i was on leave so couldn’t reply earlier.I just want to share some interesting findings with you.I enabled DTX with AMR(DL-FR/DL-HR/UL-FR) in my network and quite surprisingly , no degradation observed in Quality Handovers whatsoever!!! The AMR Interference handovers are disabled so ofcourse no degradation for them either 😛

Infact Quality handovers have reduced sightly.This leads me to the conclusion that maybe in the new Versions of the Software, there is no problem of increase in Quality/Interference Handovers when using AMR +DTX + ALU 😉
I remember even the B-10 Migration Expert telling us not to enable both DTX and AMR at the same time as it causes degradation in terms of Quality/Interference HOs 🙂

P.S: I tried ur email id but got Delivery Notification Failure 😛