# Calculation of threshold for triggering event A2

Hi Experts.

Any thoughts on this? What is -140 in the formula `Threshold = -140 + [a2 threshold-RSRP]`?

It is qrxlevmin in dBm.

Thanks.

A2 threshold RSRP.

A2 event is triggered when the serving cell RSRP goes below the set threshold value in the eNB settings.

@mac , is this a public website? If yes, then please can you share the link for our reading as well?

Sure.

Still a bit confused about A1 A2 searchthreshold and A2 threshold.

It says on the snapshot that [a2threshold-RSRP] is 37.

How it came up to 37?

What is the value of a2threshold? And RSRP?

All: any idea why it is calculating hysteresis with * 0.5?

In RRC reconfiguration msg in measurement config:

Different measurement config and object ids are defined for different kind of measurements.

For even A2 RSRP THE CACULATION IS 140-configured value of Information element in measmurment config.

So if the i.e. in RRC reconfigure message for A2 event is saying 37 means when serving cell becomes worse than -140 + 37 means -103 than event A2 is triggered.

Similarly Hysterysis IE value is calculated as IE Element * 0.5 meaning minimum hysteria can be defined as 0.5 dB.

-140 is minimum RSRP supported in LTE network in NR It’s is defined -156 by 3gpp.

I hope it clarifies,

Any differences between A2 thresh and A1A2searchThres?

I think you need to learn from the basics…

Depending on operator needs these thresholds are defined to minimise ping pong and early handovers.
Operators define as per their need.

So what is hystersis? Can you answer this?

If you can answer this than only I can go deeper otherwise I will have to explain a lot.

Yes sir I need to maters the basics.

I am a newbie, with limited knowledge on optimisation.

Glad to find a place to learn from you all masters…

Okay dear, let me find out some basic tutorial which is even basic then the one you are referring and will share with you one to one.

One can learn from GSM hysterisis which is base, good to study.

There are k, m factors and offsets.

A2 threshold will work in normal cases and a1a2search will come in mcpc side.

Search in Ericsson docs, you can find out easily.

Thank you!

And A2 for inter-freq… only last thing… I can’t find A2 threshold…

A2 is for both inter freq and inter rat.

A1a2 search threshold, you can find in MCPC parameters.

In MCPC do you need to configure the primary and secondary if the feature license is on?

From telecomhall expert @zango1986

Heheh thanks… I think I need to navigate more in the forum…

Very nice explanation dear .
Thanks a lot