CCO LTE->GSM Query

4G LTE
1

Hello experts,
Anyone can help me understand CCO LTE->GSM in Huawei?

These are the counters I have for mobility LTE->GSM (excluding CSFB)
L.CCO.E2G.ExecAttOut (None) with high count;
L.IRATHO.E2G.PrepAttOut (None) and L.RRCRedirection.E2G.Coverage (None) with low count.

Basically my HO interRAT L2G is set properly as there are very little per day.
But there are lots of CCO (CCO = Cell Change Order) L2G which i think is a problem in the network.

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2

Why did you open CCO?

3

Check:

  1. L2U attempt and failure have same trend?
  2. L2G failure increased at specific cell or area?

Also: Have you implemented any change like any feature activation?

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4

Its says if PS-HO or NCCA is not supported by UE, then UE will do CCO.
Do you have it deactivated on your network?

My UMTS coverage is smaller than my GSM coverage. I have G900 and L800, and UMTS only 2100.

5

I don’t know if is in most network, but in the network we don’t have PS-HO available.

6

I don’t have it too. We do redirection, and CSFB to 2G.
Do you have Huawei nw?
The CCO switch is located in ENODEBALGOSWITCH MO.
I will try to Deactivate it tomorrow and check impact.

7

Yes my strategy is Redirection, not PS-HO. It is better to improve CST.
And I don’t have CCO activated.
It is normal to have Redirection to 2G. Maybe some UE do not support your 3G bands. I faced similar case.
For better assessment check the ratio between 2G & 3G Redirections.

8

I have lower 3G coverage than 2G coverage…
From what I understood, CCO is a type of PS-Handover.
Anyone has some experience with CCO? Is there any requirement for the CORE network?
From the KPI, it seems bettter to deactivate CCO.
I have improvement in LTE paging when i deativated it.
So after i deactivated the CCO, now i have L2G Redirection instead of CCO
I will continue to monitor it, and will check my HO threshold L2G. I think the issue might be there as well.

9

Some simple and easy to understand info about Difference between CCO/PSHO/Redirection, from alltechstuffinoneplace blog:

Redirection

eUTRAN does not prepare the target Inter-RAT RAN with the UEs info.
It just releases (with redirect info) the UE connection.

CCO

Cell Change Order, only supported for GERAN, does not prepare the target Inter-RAT RAN with the UEs info.
It triggers CCO, as a part of which it provides the parameters necessary for the mobile to find and synchronize to the destination cell(SIB info), for UE to access the target.
It makes sure the UE completes CCO procedure and e-UTRAN connection is only released after that.
If the GERAN connection is not successful, UE is not disconnected from e-UTRAN.

PSHO

Pre-registration, pre-allocation of resources, with target Inter-RAT RAN happens.
Handsover using HO-preparation/HO-command

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