- This topic has 13 replies, 1 voice, and was last updated 3 years, 5 months ago by pix.
9th December 2011 at 12:44 #67603mXaGuest
Can u give ur opinions on pros & cons of enabling/disabling 3G to 2G handovers in PS domain ?
mXa10th December 2011 at 09:11 #67604pixGuest
i didn’t know the PS Handovers already existed in 2G. Which vendor is it ?
I don’t see any cons, but I assume it requires a good tuning of parameters so that RNC and BSC can communicate.
the pros is that there is no interruption of the PS transfer while the MS is moving from 3G to 2G. A reselection would take about 2s to 5s to complete, during which the transfer is stopped.
pix10th December 2011 at 12:16 #67605mXaGuest
Sorry, I was in a hurry and didn’t explain the problem quite well. U r right, there is no HO between 3G and 2G. What I meant is the SGSN context transfer between both SGSNs after RA request.
Now, is it favorable to:
-keep MS on 2G after reselection & open the way for another 3G reselection when conditions are better?
-keep MS on 3G and don’t perform 2G reselection?
mXa11th December 2011 at 21:08 #67606pixGuest
ok, now it makes more sense 😉
i’d favour going to 2G when the 3G coverage starts to be too low. You don’t want to extend your 3G coverage beyond its nominal cell range. Indeed, that would generate more noise for every other 3G user.
So I would activate the 3G-2G reselection in PTM mode, just before it is too late.
I guess you already actiavted this reselection in Idle Mode ?
And of course, activate it the other way around, but with enough hysteresis to avoid ping pong reselections…
(I know it all sounds very theoretical, but finding the perfect solution for you would require drivetests and extensive stats analysis…)12th December 2011 at 08:16 #67607mXaGuest
I am working with this current setup but here comes the question. And yes, reselection in idle mode is enabled.
– Having heavy 3G data usage will send u to 2G most of the times.
– Will u start with 3G and get most of the time transferred to 2G? because even making aggressive thresholds will allow more users to use 3G data which will lead to same result eventually.
– Keep the MS on 3G but in case of heavy data usage, MS won’t have a good HSDPA throughput (because 3G penetration increased). However, this will still be better than 2G experience in terms of throughput.
Know what i mean?
mXa13th December 2011 at 18:01 #67608pixGuest
I’m not sure I understand. Could you explain what you mean by
“Having heavy 3G data usage will send u to 2G most of the times.”
Pix14th December 2011 at 10:10 #67609mXaGuest
By heavy user traffic,I mean something like BH traffic.
So, 3G cell would shrink and Inter-RAT scenario to be considered.
mXa14th December 2011 at 18:02 #67610pixGuest
it sounds like you have a great test scenario that you should do with a drivetest 🙂 With qoS stats, I’m sure you could assess how badly the 3G is while it is loaded (looking at reselection %, coding scheme used, etc)
IMO if the 3G is so bad that the MS reselects the 2G, even with the most aggressive thresholds, then be it. But that has to be verified on the field.
pix29th December 2011 at 10:01 #67611KamalGuest
no more pros & cons at all…!!
Only few thresolds & proper configuration @ sgsn..
We have implemented PS HO from 3G to 2G in network sharing..!!
We don’t have 3G spectrum so using other operator’s plmn for 3G…!
in this EPLMN,we are doing fine PS ho..
Kamal18th January 2012 at 04:00 #67612NirajGuest
Can you please share the required definitions at SGSN end.We are facing issue with 3G-2G PS HO.The cell order chage message we are getting but after GPRS suspension requestPDP context is being activated in 2G and after that it comes under Standby mode.Speed becomes zero and we needto switch off the phone again to use data services.
Niraj23rd April 2017 at 11:01 #67613AyatGuest
My question about the formula
We have two formula for inter rat ps handover umts to gprs
1 is ps inter rat outgoing success / attempts
AND the other vendor using cco
Cell change request to define
Inter rat ps outgoing ho to gprs
So we have to work with one kpi formula ?
Which one is reflect the right value for ps ho ?23rd April 2017 at 21:57 #67614LEMAUREGuest
you should better use the first formula as it is based on 2G neighbor measurements (real HO) whereas cell change is rather reselection/redirection which in fact doESn’t need neighbors to happen; therefore is not assimilated to HO24th April 2017 at 19:16 #67615AyatGuest
Actually i have read a lot of docs about thi since long time , and i think CCO is seamless handover
But cco no need to resouecse reservatuon before ho
Our formula only consider cco procedure and ps inter rat ho is zero
Also 3gpp docs define ps inter rat umts to gprs as cco30th April 2017 at 19:30 #67616pixGuest
CCO is not a handover : resource is not reserved beforehand, network doesn’t know that mobile is changing cell, and mobile has to do a standard (full) setup on the target cell.
It is possible to perform a real PS HO from 3G to 2G, involving a procedure which is specified in 3GPP
as “IRAT HO”. Alternatively it is also possible to use the CCO to perform mobility from 3G to 2G. Both procedures exist, and the operator has to choose whether or not to activate PS HO.
Activating PS HO will (mostly) replace the CCO.
Most operators I know do not activate PS HO, in order to avoid compressed mode during PS transfer. They’d rather let the PS transfer continue until the drop. Since it is “bursty”, there are very high chances that the transfer will be over before the drop.
So yeah, back to the point, you can define the KPI for mobility PS 3G to 2G based on CCO and/or PS HO, whichever one is used.