floaty
Please read this one post: http://forum.mikrotik.com/t/sxt-lte6-carrier-aggregation-3uk/137455/1
With CellLock at this B1 as primary-band you reach better speed.
Read part about cell-monitor feature!.
Of course proper documentation what you should read first is here: https://wiki.mikrotik.com/wiki/Manual:Interface/LTE#Using_Cell_lock