20-01-2012, 05:07 PM
PON technology
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attenuation per unit length
-reasons for energy loss
-copper: resistance, skin effect, radiation, coupling
-fiber: internal scattering, imperfect total internal reflection
.so fiber beats coax by about 2 orders of magnitude
-e.g. 10 dB/km for thin coax at 50MHz, 0.15 dB/km l =1550nm fiber
Access network bottleneck
.local area networks
use copper cable
get high datarates over short distances
.core networks
use fiber optics
get high datarate over long distances
small number of active network elements
access networks (first/last mile)
.long distances
so fiber would be the best choice
PON advantages
.shared infrastructure translates to lower cost per customer
-minimal number of optical transceivers
-feeder fiber and transceiver costs divided by N customers
-greenfield per-customer cost similar to UTP
.passive splitters translate to lower cost
-can be installed anywhere
-no power needed
-essentially unlimited MTBF