The changing, of {HEAD ~ the power levels} may be fulfilled in {TAIL ~ any predetermined order}, for example, in step by step increasing or decreasing order 
The changing , of { HEAD ~ the power levels } may be fulfilled in { TAIL ~ any predetermined order } , for example , in step by step increasing or decreasing order
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH