A novel fiber-optic local access system adopting the “service-uniform” ONU

A novel fiber-optic local access system is presented that removes the DSPs from each optical network unit (ONU) and places them into the central office (CO). The proposed system yields a small, service-uniform ONU. The service-uniform ONU supports a wide range of narrowband services with no distinction; plain old telephone service (POTS), ISDN basic rate access (BRA) etc. Moreover, the proposed system dramatically decreases the total number of DSPs needed by concentrating them into the CO. To realize this system at the lowest cost, a high-speed code division multiplexing (CDM) scheme with novel code word sets is developed. Realized as a CMOS logic device, the proposed CDM MUX/DEMUX can operate at 250 MHz which corresponds to 50 channel multiplexing of any service in the 3.4 kHz~320 kHz bandwidth