The embodiments of the invention relate to {HEAD ~ a system} for improving energy and {TAIL ~ cost} efficiency in a passive optical network 
for improving
The embodiments of the invention relate to { HEAD ~ a system } for improving energy and { TAIL ~ cost } efficiency in a passive optical network
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH