The IEEE approved the IEEE 802.3ca 25G/50G-EPON standard at its most recent meeting, June 4, 2020. The standard describes the technical details of an Ethernet-based PON that can support one or two wavelengths of 25G (the latter achieving an aggregate capacity of 50G), as enumerated in a recent blog by Curtis Knittle, vice president, Wired Technologies Research and Development at CableLabs and chair of the IEEE P802.3ca Task Force, on his organization’s website.
Unlike the multi-wavelength NG-PON2, IEEE 802.3ca PONs will not require tunable optics at the optical network unit (ONU) endpoint to support the two 25-Gbps wavelengths. The ability to use fixed optics should make the approach easier and cheaper to deploy than NG-PON2. The wideband optics will operate in the O-Band without dispersion compensation, Knittle writes. The top-end aggregate transmission rate of 50 Gbps also is greater than the 40 Gbps current generation NG-PON2 systems are designed to support. (The NG-PON2 standard accommodates up to eight 10-Gbps wavelengths.) The specification is designed to enable symmetrical 10G to coexist with either symmetrical 25G or 50G traffic on the same fiber as well. 25G/50G-EPON will support the same split ratios as earlier versions of EPON as well as a nominal 20-km reach.
The ball is now in the court of the technology vendors to commercialize such high-speed PONs. Huawei has discussed its work in proprietary 25G PONs previously (see “Huawei touts symmetrical 25G PON”).
The P802.3ca Task Force originally began work in 2016 with a goal of developing 100G-EPON as well as 25G- and 50G-EPON. However, the 4x25G avenue was abandoned in the face of several technical and economic hurdles, including the difficulty of staying within ODN power budgets and finding four wavelengths that would promote interoperability at a reasonable cost.
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