You probably want detect offline and do action like reconnect.
Check this
Simple watchdog: http://forum.mikrotik.com/t/sxt-lte-4g-cat6/134468/1
Advance watchdog: http://forum.mikrotik.com/t/tx-rx-fp-rx-dropped-pppoe-account/132656/1
Watch LTE parameters: http://forum.mikrotik.com/t/r11e-lte6-2ca-not-staying-connected/136004/22
this help you see whats happend and do any action if offline exist.