if you have 1000 sdcch req. and each sdcch usage lasts 3.6 seconds –> 1 erlang
if you have the same 1000sdcch requests, but due to delay in the authentication or ciphering phases (or tmsi reallo), each sdcch lasts 7.2 seconds –> 2 erlangs
the duration of the sdcch affects the occupancy of the channels.
got it ? or you need an analogy ? at the supermarket, whether each client stays 30 seconds at the cashier or 10 minutes, that will highly impact the “congestion”. The queue of clients will greatly increase if each stays 10 minutes. I can relate to that :)) i always choose the wrong queue at the supermarket.