a3 offset, hysteresis a3, time to trigger event a3, filter coefficient for a3

Event a3 occurs when Reference Signal Received Power of Neighbour > Serving

Refer to 3GPP TS 36.331

FACCH is assigned whenever a SDCCH has not been dedicated for a particular user and there is a handoff request); The FACCH gains access to a time slot by “stealing” frames from the traffic channel to which it is assigned.