Please read that information:
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
LOG & Watch LTE parameters: http://forum.mikrotik.com/t/r11e-lte6-2ca-not-staying-connected/136004/22