This scenario allows for each ONU to use lower speed and lower cost
electronic circuitry, although it also requires four times the number of receivers
and requires data stream??“recovery processing. Such a solution is, therefore, most
attractive when deploying 10 Gbps EPON systems over older outside plant (OSP),
where dispersion is significant and serial 10 Gbps operation is difficult.
?– In another possible upgrade scenario, related to the one above, each ONU may
contain a single transceiver module tuned to receive one of the four downstream
wavelengths, thus providing 2.5 times the downstream capacity of today??™s EPON.
A simple spatial upgrade might be achieved simply by taking a subset of ONUs from
one EPON and relocating this subset onto a new EPON. In this scenario, a new trunk fiber
is deployed from the CO, spanning all the way to a new PSC, to which some branches
are reattached. To avoid the construction costs associated with two fiber deployments,
this upgrade fiber can be predeployed at the time of the original deployment.
Alternatively, some network operators deploy EPONs by placing the splitter in the
central office.
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