TCH_TA dropped calls ( radio link failures with a TA>55 )

[zzeia08]

HI all dear 2G experts :-)
I have problems with two cells after the swap from NSN to Huawei SRAN.
After the swap the DCR is increased with the cause TCH call fail ->TCH_TA and from counters I can see that all radio link failures are with a TA greater than 55 ( 55>TA>63 ).
I would like to know if someone of you knows how to improve DCR without loosing coverage ( no change in PTOC or antenna's tilt ).
It is clear that there are no hardware problems on the equipment.
Thanks in advance for your help.

[patek1968]

if you see abnormal TA measurements, maybe there's an illegal repeater/s in that area..you should escalate this issue and find that illegal repeater/s..=)

[usama0795]

apply TA based HO as if TA crosses 30 trigger distance HO to another cell / check neighbor definition since most of the time after swap neighbor definitions are not properly defined and I think in ur case call is dragging on the cell and getting dropped.....

[airian]

You can also play with rx level access min so that MS may not camp on this cell from that far. this will also decrease drops too.

[justdream]

Dear,
55>TA>63 is very big distance - why you need to cover all this area?
what's the distance bet. your cell suffers from high CDR and 1st. defined neighbor?

[Budaxbaix]

Hi,

You can check this parameter if to small can lead drop call due to MS can access even the signal is bad
RACH Min. Access Level
Minimum Access RXLEV

Thanks

[airian]

Dear Zzeia,

Kindly confirm if your radio link failures are high on TA= 55 TO 63 OR on TA > 63. As in my case i can see radio link failures at TA>63 even for city cells which is not possible. its possible that the BSC might not be able to find the exact TA at these failure hence it has put it into this counter. Plz share.

[usama0795]

check if extended cell feature is activated on the cell....

[Muaimuai]

OK ^___________________^

[olly]

Hi,
if the cells are country cell (in rural area) u can increase your RLC timer, but in this case, the MS will be using resource for a longer time than necessary, prolonging the actual time for RLC time-out.