At this week’s OFC exhibition in Los Angeles, the Optical Internetworking Forum (OIF) is showcasing the first electrical interfaces running at 56 Gbps, effectively doubling the current 28G electical interface specification. The OIF has five CEI-56G specifications are under development, such as platform backplanes and links between a chip and an optical engine on a line card.
To address power consumption issues, the OIF is pursuing two parallel tracks: using 56 Gigabit non-return-to-zero (NRZ) signalling and 4-level pulse amplitude modulation (PAM-4) which encodes two bits per symbol such that a 28 Gbaud signalling rate can be used. The 56 Gig NRZ uses simpler signalling but must deal with the higher associated loss, while PAM-4 does not suffer the same loss as it is similar to existing CEI-28 channels used today but requires a more complex design.
More online…
http://www.oiforum.com/oif-shows-56g-electrical-interfaces-cfp2-aco/
