The only shortcomings of the presented EPON system stem inherently from its advantages
i.e., relaxed PHY requirements. Lower grade lasers and receiver modules as
well as the application of 8B/10B channel encoding result in increased transmission
overhead when compared with competitive ITU G.984 GPON systems. This fact has
been recognized by the EPON proponents though it has been argued that the increased
channel efficiency of GPONs comes with a much higher price tag, leading to less costeffective
solution. It is therefore difficult to identify whether the said relaxed PHY
specifications are indeed disadvantageous for EPONs or whether they were originally
the enabling factor for the wide adoption of the said system and its robustness.
Typical Deployment Scenarios
The EPON is a point-to-multipoint (P2M) network, with a single CO providing services
to a number of residential/business customers. All transmissions in the EPON
system are performed between the OLT and ONUs, where the OLT is typically a
blade in a CO chassis, while the ONUs are more commonly deployed as stand-alone
boxes, with their exact location depending on the deployment scenario (home for
FTTH, curb in FTTC, business office in FTTB??”see Figure 7.
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