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Hi all!
I work with Alcatel BSS. Recently we bought and activated TFO. There are lots of questions, but the first:
What does parameter TFO_MATCH mean?
It enables or disables resolving the mismatch of codecs for two sides – but it’s an entity of the very TFO, isn’t it? If we set TFO_MATCH=DISABLE, will TFO work at all?Hi,
I need to check the doc at work, because i forgot the details. Unfortunately, this is a 4 days weekend here..
Could you post the full definition of the parameter and its possibles values ? That might help me remember 🙂
Pix
Dear Pix,
The exact parameter’s name is EN_TFO_MATCH.
Definition: This flag enables/disables TFO codec mismatch resolution function.
As I understand, when we detect codec mismatch on two sides of link we should begin TFO negotiation and try to find the best suitable codec for both sides – and it’s the entity of TFO. What will happen if we set EN_TFO_MATCH=disable? Will TFO negotiation start? How does parameter EN_TFO_MATCH work?Thanks a million!!
Oh, ok.
If MATCH = DISABLE, it means that the two MS starting their call with different codecs (EFR and HR for example), will not try to resolve the issue by finding a common codec.So the resolution is disabled.
Only case when TFO will work is when both MS start with same codec already.
Dear Pix, thank you.
Now I understand the principle, but another question:
What is the aim of using TFO in such cases? If we have the same codecs on both sides – we don’t need futher negotiation, I suppose?
Oh, now we have a huge problem with our KPIs, in particular – TCH congestion (after TFO activation) because we use rather not objective formula, including counters for HO preparation – MC541a, MC551, and – MC561 (intracell HO failures). Therefore in areas with high TCH load we can see enormous increase of MC561. I’ve changed the value of parameter “TFO HR when loaded” from = TFO preferres to = TFO_HR_only. It works for homogenus cells (all RSLs are FR or DR), but for not homogenus cells (some RSLs are FR, and some are DR) the problem of high MC561 still exists.We use B9 so we’re limited in BSS resources for HR :(.
That’s why I want to experiment with EN_TFO_MATCH.
Thank you very much, Pix, and – I wish you nice weekend 🙂Hi Ivann,
change TFO HR WHEN LOADED to “TFO HR not forced” and you’ll have decrease in congestion. We had this problem few months ago, I raised that question in this forum.Dear Gents ,
which channel ( SACCH | FACCH ) is responsible for alerting in Busy MS … and what exactly the process…
Best Regards,
Ivann,
“What is the aim of using TFO in such cases? If we have the same codecs on both sides – we don’t need futher negotiation, I suppose?
”no, no need : the match is “natural”, TFO is enabled in the call.
Amkam, FACCH.
Dear Rex,
yes, we have made such experiment (set TFO HR when load = TFO not forced) and got enormous MC561 on high loaded cells (with homogenus RSL – all DR). Thus we have 37% of such cells so we had to refuse from this value.Ok Ivann,
then leve it only parameter EN_TFO=ENABLE and disable the other parameters related to TFO.
Regards,
RexHi, could you give the trigger condition of MC561 ? What exactly is it counting ?
You must ensure this counter is really relevant to assess network quality.MC561 = intracell HO congestion failure
Ok, that makes sense. For best HR usage and less congestion, set:
EN_TFO = Enable
EN_TFO_AMR_WB = Enable (are you using that yet ?? :)) )
EN_TFO_MATCH = Enable
EN_TFO_OPT = Disable
FORCE_TFO_HR_WHEN_LOADED = 1 (TFO HR only)
FORCE_TFO_VS_AMR = 0 (disabled)
KEEP_CODEC_HO = 0 (free choice of the codec)Keep Codec HO = free choice means that when MS is in FR and goes into a loaded cell, then it’ll get a HR channel. Then, thanks to the TFO_Match, the other MS will downgrade to HR (if it was previously in FR also), so that both sides are in HR. TFO will then resume.
Beautiful 🙂
Dear Pix,
thanks a million!I’ve just applied the set of these parameters (as you had adviced)for all cells in one BSC. Really, it’s very elegant decision 🙂
But what does EN_TFO_AMR_WB mean? I can’t find it neither in OMC-R nor in Telecom Parameters Dictionary (we use B9). :))I am looking forward to get the results of the experiment 🙂
Once again many thanks !Yes, please, let me know 🙂 It should give you the benefit of TFO without any impact on the congestion.
The AMR WB is a new set of AMR codecs, which are “wide band”. The bitrate of those codecs are the same as the EFR (it’s not “broadband”), they still use one timeslot.
But the voice quality is simply amazing 🙂 they are using new algorithms to code the voice.It’s a B10 feature, that requires new transcoder MT120 board (the MT120-WB).
Normal you don’t see it in B9.
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