LTE: Event A3 or Event A5 - which one to use?

Question

We currently use Event A3 on our network but we are starting to explore the idea of using Event A5 instead for Inter-Frequency Handovers.

Our LTE network is still very much in the development stage as sites are being rolled out on a weekly basis, this will continue for the remainder of this year.

I would be of the opinion, which was established based on theory, that although A5 does offer some small benefits over A3, A3 would in fact be the better option for our network.

Can you explain what the benefits of using A5 instead of using A3 are and which would you recommend?

Also what changes in KPI's would you expect to see if we were to change from A3 to A5?

Answer 1

As per my understanding, Any of the event a3 or a5 can be used for inter frequency HO. eNodeB configures these event for an UE on the basis of UE capability. I think if UEs does not support a5 event, in that case a3 event can be configured for both intra as well as inter frequency HO. If both the events can be supported by UE, in that case we have option which event should be better option.

Triggering criteria of the LTE event are as below.

A1 Serving becomes better than threshold
A2 Serving becomes worse than threshold
A3 Neighbour becomes offset better than PCell
A5 PCell becomes worse than threshold1 and neighbour becomes better than threshold2

From these event triggering criteria, a3 can go for any bad signal condition of serving cell( RSRP) but event a5 restrict the serving cell bad condition of signal strength(RSRP) by defining the threshold1.