RTT and PLR(Packet Loss Ratio)

My problem with RTT is that i can't use ACKS and i'm only sending messages.

If the RTT is the time required for a signal pulse or packet to travel from a specific source to a specific destination and back again.

how do I do that using my code, if i can't use ACKS? :c

I searched a lot and I rellay don't have any clue