高密度多波長分工系統 光纖到社區或建築物 光纖網路 光塞取多工系統 光交接系統 DWDM Dense wavelength division multiplexing system FTTC/FTTB Fiber to the curb or building Optical network OADM Optical add drop multiplexing system OXC Optical cross connect system IP Internet protocol over DWDM