Can RSRQ threshold for A1 and A2 solve VoLTE DCR due to Handover?


Can RSRQ threshold in 850 band for A1 and A2 solve VoLTE DCR due to Handover?
And will it be best to have A4 enabled in such case for execution?

A2 is just starting event for inter Freq /inter RAT HO then UE will go for A3/A5 basis scenario as defined.

But here if you use RSRQ based trigger quantity for VoLTE then definitely it will avoid UE movement on highly loaded cells giving more space to VoLTE call on less loaded cells.

A4 is used if neighbour better then defined threshold it can be basis on RSRQ or RSRP but not really used as serving cell condition not look here, so for VoLTE A5 is most recommended.

Even A3 is not recommended for VoLTE due to ping pong handover leading to mute call.

So A5 RSRP and A1 and A2 RSRQ threshold will lead to issues.
Mainly from 850 to other bands.

We used RSRP only for A5.
RSRQ not tried.

But A1 and A2 RSRQ can help with A5.

Can you please elaborate how A5 based RSRP HO for VoLTE is good as compared to A3 based RSRP HO?

It’s seen with A3 based MR if A3 offset kept 3 then it lead to frequent handover leading to ping pong kind of scenario as such target cells easily achievable.

So leading to issues like VoLTE call drop, mute call etc.

With A5 UE need to look both serving and target but with A3 only UE need to look target cell so with serving cell even in better coverage still UE move to target cell which can be more loaded as well probability there.

I don’t think the RSRQ will be a good solution.
RSRP more accurate I think.
U need to investigate what the reason behind the high DCR.
And if you face VoLTE call drops.
What about SRVCC feature?

Ok but A3 based HO is fast as compare to A5 based HO.

In case of A3 based HO it’s easier to Handover to target cell in case UE in poor rsrp and Target cell is available.

In A5 based UE need to satisfy both the condition, which delays HO.

Please correct me if I’m wrong.

Thumb Rule, for:

  • Intra frequency - A3 only
  • Inter fre-RAT - A3 or A5

A3 only disabled for VoLTE, not for data HO as mentioned above why it disabled for VoLTE?

We have seperate thresholds for QCI1.

I just have one comment here regarding that A3 is faster than A5, as for A3 event to be reported that means neighbor cell is higher than the serving cell with a certain threshold, so UE should measure both serving and neighbor cells to decide by how much the neighbor cell is higher than the serving cell.

For A5 event, the UE will measure both as well.

The only difference I can see here in the reporting of both events A3 and A5. So, how can A3 be faster than A5 if in both cases, UE should measure the serving and neighbor cells? Please correct me if I am wrong.

UE will not wait in A3 for serving to degrade if it find target let’s say 3 dB better then serving it will handover where in A5 UE will measure both serving and target as per threshold 1 (serving degrade) and threshold 2( target better).

For VoLTEe call that’s why A3 recommended to turn off to avoid call drop, mute call due to ping pong HO scenario in highly overlapped area.

Yes, I understand this point, however my main concern is when radio conditions are the same for both A3 and A5 at the serving cell where the conditions for both events are achieved, then both are similar to each other and one is faster than the other.

Please correct me if I am wrong. :slight_smile:

Though the radio condition is smiler and both A3 and A5 criteria getting achieved.
To ease out A3 happened first then A5.

But why A3 will happen first?

In one 5G network, A3 was used for intra-frequency and then A5 was enabled and HO attempts increased too much which means A5 triggered some HOs which was not done earlier by A3 which I didn’t honestly expect although similar triggering was set for both events and this let me think again about which event is triggered faster.

Let’s consider Two Different scenario for interfrequency HO

A3 Based HO

A1 -90 A2 -95 and A3 is 3 dB.

So A3 Event will trigger if NBR Cell is better 3 dB better than Source cell, and if NBR Cell is -95 and Source cell is -99 than A3 will be triggered.

Now In Case of A5 Based HO where A2 = -90 A2 = -95 and T1 = -100 and T2 = -105 dB. So A5 Will only trigger if Source cells is -106 and NBR Cell is -99.

So i think A5 Event is delayed as compare to A3 Event.

Rest all the parameter Like TTT/FC are same for both Scenario.

You are right!

A3 is considered more aggressive handover strategy whereas A5 is more reliable.

In A3 only 1 condition needs to be met, whereas in A5 2 conditions need to be fulfilled for handover.

Hi. Is this for 5G.or VoLTE scenario?

It’s for LTE and VoLTE.