Passive Optical Networks

to the assigned CO. Alternatively, local loops first connect end users to a remote

terminal (RT), which multiplexes the individual signals on a feeder line. The

feeder line in turn connects to a local CO. Feeder lines provide pair gain by

reducing the amount of wires required to connect each user to the CO.

There is trade-off between the cost of electronics in the RT and the savings

achieved from the pair gain. If the cost of RT is high, in general, more users are

required to share the cost, and the length of local loops will tend to be longer.

The local loop distance where the cost of RT starts to make economic sense is

called prove-in distance. Prove-in distance reduces as electronic technologies

improve. In a PON system, the RT is simply a passive ...