2G optimisation of urban sites

[leelio]

hello engineers,

in our 2G network we have been suffering from critical frequency interference in areas which are highly congested. we have been trying to optimise the site, by reducing sites footprint,and frequency retuning without major recognized changes in term of drive test or network KPIs.

we are now thinking to do more parameter optimisation such as to reduce Minimum Access receiving level from existing 8 (-102dBm) to 15 (-95dBm); what are your opinions on this? and what more can you suggest to be done.

Our vendor is ********.

thanks guys.

[salmeterol]

hello,

You are working in highly congested areas, do you have either tch or sd congestions?

Don't forget "Congestion Relief Handovers", you should establish margins "from congested cells to uncongested cells" to easily to handover.

Also you can retune PBGT and "Cell Reselection Hysterisis" margins.

First you should decide: where do you want to transfer the congested traffic?

And I would like to learn Downlink Quality Handover percentages for congested cells !!!

Don't try to change Min_access_level, you throw out some subscribers from network, therefore operator loses money !!!!

[salmeterol]

If you want to learn more, then pm to me...

[leelio]

Hello salmeterol,

Thanks.

The area is not that congested in sd/tch; but we have lots of sites in one area as to meet capacity need. we have been thinking of this min_acc_lev because here we'll eliminate MS below threshold (-95dBm), as most cells seems to overshoot. From DT logs the best neighbors range from -95dBm to -70dBm, from this fact we dont see the importance of keeping MS below -95dBm. And issue we have is more interference related and not congestion.

However, i stand to be corrected and learn more..

[Rashid]

better way doing on physical changing rather than on parameter setting, it will be make some degradation on receive level. Changing on parameter is last choicefor optimization

[salmeterol]

if your cells are overshooting, then you should consider e/m downtilt or power reduction.

don't beleive dt logs so much. you cannot know about behind of walls with dt.

don't underestimate loses on walls...

And reevaluate frequencies about co-/adj- channels...

[ludali]

Hi Leelio,

I am of the view that in such a situation tuning of physical parameters of antennae is critical. It's important to therefore review the antenna heights and tilts (and may be azimuths).

It may be of use if electrical tilt is used instead of mechanical (unless antennae in place are not capable of electrical tilt).

Having reviewed the physical parameters then it may also be needed to review the BCCH plan together with the frequency hopping strategy. The plan in Handover Relations may as well need to be reviewed.

One thing that may be of disadvantage in using a too high value of ACCMIN is that it may lower your network's competitiveness on international roaming.

BR,

ludali

[leelio]

Hi Ludali,Salmeterol

as per my original thread, i'm done with physical optimisation, alot of downtilting and height reduction has been done on site to control footprint as much as possible.

my concern here is to get much extra parameters that may help to improve interference (&speech quality) situation,and ofcourse we do frequency hopping on both layers 900&1800. But our freq band is too small that we have nothing much to do on frequency retuning (alots of frequency retuning have been done). Through drive test neighbor relation was also reviewed without help.

@Salmeterol; power reduction in what sense? which parameter do you prefer? {or do you mean maximum transmit power?}

i've got lots of limitation, but the situation is real as it is.

guys,please advise me more..

[adewijaya]

What's TRx config do you deploy? i think on 2G network if you just have small frequency so cann't deploy more TRx on every single site consider with MAL Frequency

[salmeterol]

i mean bts output power

[Processor]

i mean bts output power

i try to stay clear from messing with this parameter cos u could lose coverage drastically.....

I would prefer you show us weekly stats for any of these affected sites so that we can further help out in this regard

[jimjim]

Dears,

Did you consider using DCS1800? In some cases using new frequencies will totally eliminate interference.

******** usually provide optimization services, they plug a prob into your network, and start collecting messages, later on they will come out with an optimum frequency plan which will solve a lot of interference issues.

:)
Regards,

[leelio]

Dears,

Did you consider using DCS1800? In some cases using new frequencies will totally eliminate interference.

******** usually provide optimization services, they plug a prob into your network, and start collecting messages, later on they will come out with an optimum frequency plan which will solve a lot of interference issues.

:)
Regards,

sure,******** use to do IOS download every end of year; but now they dont support us any more..we do things on our own

[leelio]

i try to stay clear from messing with this parameter cos u could lose coverage drastically.....

I would prefer you show us weekly stats for any of these affected sites so that we can further help out in this regard

i will come up with them soon...thnx

[leelio]

What's TRx config do you deploy? i think on 2G network if you just have small frequency so cann't deploy more TRx on every single site consider with MAL Frequency

we normally deploy 2/2/2 (900), 4/4/4 (1800)

[Alex_R]

Dear Leelio

i think with all limitations above, you have to deploy more sites and reduce number of TRXs per site