- This topic has 9 replies, 1 voice, and was last updated 6 years, 2 months ago by prof.
18th March 2014 at 07:16 #69544ZTEGuest
Who can help me to know that why we have had significant KPI gain (CSSR,UL Quality, DL Quality ,. . . )after increasing the half rate percentage from 10% to 95% in our network, while the result should be vis versa.
Please help to know that.18th March 2014 at 14:29 #69545pixGuest
The usage of your frequencies is much reduced, which means that there is much less interference in your network.
This is a very very visible behaviour in case of GSM 900MHz and overshooting sectors.
pix19th March 2014 at 06:48 #69546ZTEGuest
you are righ, the interference level is low in our network, but i want to know techncially that how i can relate the increment of Half rate traffic with improvemnt of quality and KPI? normally the result should be inversly effective.19th March 2014 at 06:56 #69547ZTEGuest
From other side,we are having both GSM900 and DCS cells in our network almost equal number. and the quality is improved for both 900MHZ cells and DCS cells equally.20th March 2014 at 10:26 #69548pixGuest
i thought i answered your question :
HalfRate = less frequency load = less interference = better QOS.
It applies to all frequencies, all sites. Effects are visible anywhere.
They are spectacular on areas with high traffic and poor C/I.
Regards21st April 2014 at 15:03 #69549profGuest
Just to take it a little further. I have noticed the MOS is directly proportional to full rate proportion. I used a statistical software to extract correlation between MOS and various other network parameters extracted from the drive. The correlation with full rate came out to be .4 which is huge. I have not taken care of pre conditions for the statistical test so it may be inaccurate.
Half rate increase -> Poor RxQual
Half rate increase -> Better MOS
But RxQual should be directly proportional to MOS!
I think it is due to subjective nature of MOS; it depends on so many factors. It may be that at the time of MOS drive the utilization was low. Des anyone has a better insight?21st April 2014 at 15:59 #69550profGuest
Sorry it should have been:
Full rate increase -> Poor RxQual
Full rate increase -> Better MOS22nd April 2014 at 09:47 #69551profGuest
Can anyone please comment on relation between full rate and MOS?22nd April 2014 at 18:19 #69552pixGuest
i wrote a long reply, but it diodn’t get posted properly 🙁
When you say FR, you mean 12.2 ? As opposed to … lower AMR codecs ?
Basically it makes sense.
12.2 FR can be used up to RXQUAL 4.5
When RxQual is better than 4.5, the FR is better than lower AMR codecs.
When RxQual is worse than 4.5, the FR is suffering from interference, so the speech frames are getting deleted once in a while. That impacts the MOS very negatively, as you can guess. At his point, it is better to switch to a “lower” AMR codec, but still within the AMR FR set.
Pushing the usage of 12.2FR means that you tend to globally decrease the RxQual. If you decide to switch to lower AMR FR codecs earlier than 4.5, then the MOS will be degraded because the speech encoding won’t be as good. However, the Rxqual *should* remain stable (rxqual is not theoretically linked to the codec used, as it is measured at the physical layer – but i’m not sure how this theory would fair in the real world.)
Now, if you are opposing FR with HR, then I can’t understand it. The HR is way more sensitive to interference than FR.
pix23rd April 2014 at 19:05 #69553profGuest
I was actually talking about HR and FR for GSM.
As you already mention in this thread that increased HR penetration result in better quality due to lower frequency load. This is what I observed too. But I also observed that MOS degraded with increased HR penetration.
My question is that shouldn’t better quality translate to better MOS? Why is it the other way around in this particular case?
Thank you for taking the time to answer.