To improve the networking flexibility in the metropolitan and access area, the granularity in the optical domain has to be increased above that in the core network requiring more channels at lower bit rates. Pure dense wavelength division multiplexing (DWDM) as it is applied in the core does not seem to meet this requirement at affordable cost. We propose and analyze a network based on hybrid optical multiplexing techniques including wavelength, code, and time division multiplexing. Applied to optical packet transmisssion this approach enables several 100 all-optical channels between end users and headend with average bit rates up to 100 Mb/s per channel while keeping the installation and maintenance cost at a minimum.
Thomas Pfeiffer, Jens Kissing, rg-Peter Elbers, Bernhard Deppisch, Martin Witte, Harald Schmuck, and Edgar Voges, "Coarse WDM/CDM/TDM Concept for Optical Packet Transmission in Metropolitan and Access Networks Supporting 400 Channels at 2.5 Gb/s Peak Rate," J. Lightwave Technol. 18, 1928- (2000)