Call drops optimization

[herlynm25]

Hi experts,


Can you give me a recommendation on how to
Optimize drop call due to uplink level on 2G???

[jan74]

Hi experts,


Can you give me a recommendation on how to
Optimize drop call due to uplink level on 2G???

Weak UL level is something you can expect in an 1800MHz network. Can you clarify what levels of handovers you see due to each cause please? Its normal in 1800 to see high levels of HO on UL level, over 60% sometimes. This is because link budgets in 1800 tend to be stretched to the limit.

How do you know the dropped calls are due to UL Rx Level? Could you have issues with interference in the UL or could you have faulty hardware? Is this across the network or only some sites? Higher sites will suffer more from this. How to fix it will depend on what exactly is happening. If its a link budget issue, you can try to install Tower Mounted Amplifiers to boost the UL. If you have already done that, check they have been tuned properly. After that, check there is no intererence.

Finally, if everything is ok, then you need to consider tilting the cell in question. this will help but your coverage may suffer.

[xpdxtd]

Hi, One possible reason for UL dropped calls is interference in the UL band of the air interface in question. Example: GSM1900 interference in WCDMA 2.1GHz UL. Check your assigned frequencies, antenna separation distances and or filters on site with more than one technology.

[mike_symbol]

Collects stats timing advance and interference band of serving and neighbors.
When overshooting and interfering,retune frequncy.
When still interfered, downtilt interfering cells to your serving cell.

[louvre]

Hi,

Its a good one, as the discussion has been saying it really a tricky one because of the fact that its UL which has the problem.

Some Key points that need to taken into before going for a solution.

1. Has any significant change been done in the network which would explain the drops. i.e. Change of the hardware etc. if hardware has been changed is it inline with the spec of the equipment provider.

2. the problem with the UL is that it can drop pretty fast, faster than down link, so i recommend you to lower the POC parameter in the UL only in such a way that MS starts transmitting full power faster as speed of power control may not be sufficient enough to deal with UL reduction.

3. Also you can set a baseline value for minimum transmitting power so that mobile cannot reduce power less than that value, this has to be done with care by checking the UL interference report because setting a baseline value also will cause the UL interference to increase by a little bit.

3. MHA - Check for installed MHA in the site, whether they are working or faulty. if pathloss is very high in the band you can also go for installation of MHA which will help in reduction of drops.You can use a form of UL/DL level sample matrix to better analyse what might be the cause.

[zhanglw268]

Other factors that need to be considered:

1). Check the neighbur list whether you have missing neighbour so the handover was triggered too later and the call is dropped before handover.

2). NCC_of_PLMN_AlLOWED: check whether the sevring cell allow mobile to measure the neighour cell with different NCCs, this may cause mobile not reporting the neighbour cell so the call drag a long time than it shall be.

[ventinel]

also try the following:

1. disable UL power control
2. Check the value of MS_TXPWR_MAX_CCH
3. also check the distribution of the weak level UL, if its on all the cells or some specific cells. For specific cells, UL-DL path balance can be checked (detailed guide for Huawei 2G attached) and also check the TA distribution of worst affected cells. DL may survive at high TA but UL will be very weak at high TA.

[ventinel]

also check the manual at the b/m post. might be helpful.

http://www.finetopix.com/live-optimi...-drop-dcr.html

[ErlangB]

Hi,
1-check all alarms that appear on the hardware.
2-If you don't have a diversity install the second path or define it if you already have it.
3-check MS max power.
4- check the TA if you have a overshooting ,do down tilt and study the effect.
5- check if you have internal interference.
6- check if you have external interference.
7- install TMA to support the UL.


Thanks

[topycopy]

this really the most important KPI to tune