In most scenarios, a good
fraction of the ONUs will be idle at any given time, and the excess bandwidth will be
distributed to the active ONUs via the DBA mechanism, so on average, each customer
receives more bandwidth. This performance far exceeds that of DSL and cable modem
systems, while remaining highly cost effective. Even so, as more bandwidth-intensive
services gain popularity, bandwidth capacity will be reached at some point in the future.
Accordingly, it is crucial that EPON continues to evolve so that a smooth path for
future upgrades is available. At least four upgrade paths for EPON can be envisioned:
(1) increasing the number of individual transmission channels (wavelength upgrade),
(2) increasing the data rate, (3) a mixture of (1) and (2), and (4) spatial upgrade.
Wavelength Upgrade
Providing that wavelength division multiplexing (WDM) technology reaches a significant
level of maturity in the near future (i.e., achieves cost marks suitable for massmarket
FTTH applications), the number of individual wavelength channels in a single
EPON could be increased, adding a separate WDM overlay on top of existing burst
mode??“operated systems.
Pages:
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460