Voice in 3G

[Moon]

Hi Expert,

Could you please share your expertise on how to increase AMR traffic in 3G,
We are using 900 MHz for 2G & 2100 Mhz for 3G. the 3G AMR traffic is very less compared to 2G (About 10%)

Thanks

[twenty8]

Hi,
This is alot to do with operator strategy. The things you can do is .

1. See how many 3G capable UE is being used in the market.
2. Whether the operators has allowed 3G usage for the current GSM subs in their HLR profile.
3. Camping mode strategy , ie. Check QSEARCHI parameter in GSM as well as FddQmin.

[Moon]

Hi,

thanks for your reply,
regarding the % of 3G UE its assumed to be 50%,
Cell reselection parameters are already tuned to prioritize 3G layer, but the 3G voice traffic is still very low

[twenty8]

Is the operator recently rolled out 3G ? How was the marketing strategy to move the 2G users to 3G , ie. was it automatically or did the 2G subs have to apply for 3G access ? At least , if you have a 2G sim try to lock on 3G and see what error you get.

[Moon]

the 3G is a mature network & all SIM card are now 3G; also the number of 3G sites is almost same as 2G. what should be the max voice traffic that we can reach in a 3G sites (2/2/2 or 3/3/3)

[twenty8]

well you can then check the ratio between 2G erlang to 3G erlang in the BH in a particular cell to see the difference. The pole capacity for a 3G cell is about 60 voice calls.

I've attached a good document by Qualcomm, that explains these capacity limitations.

---->>>>>>>>>>>>>>>>>----------------
Pls give thanks & rep.

1 Introduction..................................................................................................3
2 Release-99 Cell Capacity............................................................................4
2.1 Uplink Capacity 5
2.1.1 Voice Capacity 6
2.1.2 Circuit Switched Data Capacity 6
2.1.3 Packet Switched Data Capacity 7
2.2 Downlink Capacity 8
2.2.1 Voice Capacity 9
2.2.2 Circuit Switched Data Capacity 10
2.2.3 Packet Switched Data Capacity 11
2.3 Mixed Traffic Capacity 12
3 Release 5 HSDPA Capacity ......................................................................14
3.1 HSDPA Cell Throughput 15
3.2 Average Cell Throughput 17
3.3 Average Cell Throughput vs. Voice Load 18
4 Other Capacity Issues...............................................................................18
4.1 Coverage 19
4.2 Soft Handover and Cell Capacity 19
4.3 OVSF Code Limitation 20
5 Conclusion.................................................................................................20

[Moon]

thanks for the good doc,
for 2G traffic in some cells we can reach 120 Erlang in BH while 3G cells is having max 20 Erlang in BH (& some 3G cells are having 2 Erlang in BH);
For the parameters we have Qqualmin =-18; SsearchRAT=2 dB; EcNo threshold for HO = -12dB (this parameter was decreased to -16dB but the traffic/cell in BH was increased by few Erlang only). any other parameters that can be tuned?

[RFDude_PMA]

Hi

Can you tell us the cell reselection parameters for example in E/// we have in the rllop ( isolev) in the rlsup (fddmin, fddqoff, qsc,qsi,fddmrr and sprio) and rlump (umfi in idle or active)

Do you have E/// or huawei?

[twenty8]

those are 3G > 2G reselection parameters, you need to look at 2G > 3g reselection parameters... see QsearchI, FddQmin , FddQoffset . But I would also check with CN engineer on the HLR subscription for the users as well.

[kilisuci_kdr]

Hi, what about the physical coverage?
Is it the same, are you using single band antenna or separate?
Just need to check the orientation or tilting also to make sure it has same coverge.

[RFDude_PMA]

hi twenty8

Those are E/// Commands in 2G for 2G ->3G reselc and HO.

But it seems a bit clear that is not E/// the manufacture you have.. sorry bcz I though it was.

But the issue about the parameters remains the same ... the RSCP to do a resel and in 3G the load value consider for UL. Because that can help if this value is lower it will not accept more traffic

Best Regards

[soodlhor]

maybe it will cause increment of call setup fail/drop. so, you need make trial on some cells first.

Cell Select/Reselect

in 2G Qsearch_I should be always searching, UE will camp on 3G automatically.

set Qrxmin(-115) and Qqualmin(-18) as low as possible to let UE enter to 3G easily.

Reduce SSearchRAT(2) in order to make UE reselect to 2G more difficult.


IRAT Handover.
Reduce HO Threshold Ec/Io or RSCP. it depends on your HO algorithm.

[twenty8]

also what is your configuration in GSM and in UMTS ? ie. how many radio's in GSM and how many carriers in UMTS ? is there a dedicated carrier for voice ?

[Moon]

Hi Guys,

We are having NSN for both 2G/3G network, the 2G to 3G cell reselection is already set to camp on 3G (QsearchI & P = always; FDDQmin=-12)
we also have almost the same orientation of the sectors
the configuration is mixture of 1/1/1, 2/2/2 & 3/3/3 (1st carrier is dedicated to voice, 2nd & 3rd for HS)


If we have one site 3G with 1/1/1 & HS is disabled what would be the max voice traffic that can be supported by this cell (i mean practical)

Regards

[moayash]

Hi, what about the physical coverage?
Is it the same, are you using single band antenna or separate?
Just need to check the orientation or tilting also to make sure it has same coverge

[Moon]

We have separate antennas for 2G & 3G, & most of the cells are having same azimuth & height (for both 2G & 3G)

[twenty8]

it all depends how the users are distributed in the cells, assuming 20W PA and most UEs are around a geometry of 5 , then you should be able to have 40-45 simulataneous users ... as mention this depends alot on UE distribution !