ncrement of 2G drop rate after launching the 3G

[zoro78]

Dear Experts

can any body advise for the increment of 2G drop rate after launching the 3G network and have high PS traffic on 3G on the same time, please advise for the reason

[Handover24]

Sorry but is the dcr or the number of dropped calls that has been increased?
in your network is enabled IRAT HO from 2G to 3G or not ?
Regards

[zoro78]

Dear,

drop call rate which was increased eve we are enabling the IRAT HO from 2G to 3G, given that the 3G CS re-leaved almost 7% of 2G traffic

[Handover24]

How much the dcr has increased ?
Is there a particular counter of Dropped calls that is increased ?

[auto_art]

2g n 3g are not linked if we talk about the RF enviorment.

i m suspecting some feeder swap issue if this is the case. better to analyse stats more thorough

[raid75]

Dear,

after lunching the 3G you need to adjust the formula of TCH drop rate to:

TCH drop rate= 100 X TxNDROP/ (DISNORM+TxNDROP)

due in the old formula the IRAT HO from 3G to 2G is not accounted and this may the reason behined the increase of drop rate.

regards

[zoro78]

Dear All,

regarding the increment it is almost 16% to 18% in DCR with some degradation in HOSR in same time we have offloaded the traffic by 6 to 7% to 3G network even that we have modified the formula of CDR and there is no HW problems with network or RTWP or VSWR! and I have asked about that for whom are using Huawei 6900 BSC/RNC with RAN 12 and I did not get any clear answer about that

[Handover24]

al_zamer ,
I've never seen something similar just a little DCR increased near new 3G sites activated ( due to the fact that traffic held by 2G is now made on 3G ). Anyway as in your network the IRAT from GERAN to UTRAN is enabled and in our network it is not.I don't know how it could affect the 2G DCR.
Anyway it would be usefull to you if you see in your network a particular type of TCH fail cause or SDCCH dropped cause...Have you checked which of those counters is increasing after the 3G launch ?
Regards.

[khurrambilal01]

Logically speaking 3G on 2.1GHz picks most of your nearby site CS traffic which is having better KPIs, So the leftover traffic is far away traffic with relatively poor KPIs that's why normaly after 3G launch 2G KPIs degrade.It's normal behavior.

Just take an example normaly 1800 band KPIs are better relative to 900 band KPIs the reason is 1800 picks nearby traffic with better KPIs while 900 has to pick worst traffic which can't be carried by 1800. Similar is the case here with 3G on 2100 band & GSM on 900/1800 band.

[zoro78]

Many thanks guys this is what we were thinking about but how can we proof this by Huawei counters do you have any suggestions for that

[Handover24]

According to what Khurrambila01 said ( quoted below ) check your TA distribution before and after the 3G launch .


Logically speaking 3G on 2.1GHz picks most of your nearby site CS traffic which is having better KPIs, So the leftover traffic is far away traffic with relatively poor KPIs that's why normaly after 3G launch 2G KPIs degrade.It's normal behavior.

Just take an example normaly 1800 band KPIs are better relative to 900 band KPIs the reason is 1800 picks nearby traffic with better KPIs while 900 has to pick worst traffic which can't be carried by 1800. Similar is the case here with 3G on 2100 band & GSM on 900/1800 band.

[zoro78]

many thanks guts according to simple calculations i did i found that most radio connection failures increased as TA by more than 40% this is a good proof about that :)

[Handover24]

But what about TA ( Not RLF but MR/TA )?

[zoro78]

Also it is affected with lower value almost the average was 1.2 and now it is 1.5 Km