The ONU improves {HEAD ~ cost and energy efficiency} for {TAIL ~ the PON} by entering a sleep mode that disables communication with the OLT to reduce energy consumption when the ONU is idle 
for
The ONU improves { HEAD ~ cost and energy efficiency } for { TAIL ~ the PON } by entering a sleep mode that disables communication with the OLT to reduce energy consumption when the ONU is idle
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH