TECHNICAL
network terminals (ONTs) at the customer premises. Currently, low-cost tunable receivers are not yet available; therefore many operators envision an intermediate step using XGS-PON before migrating to NG-PON2. XGS-PON uses less expensive fixed lasers and receivers in the C-Band and therefore provides a better business case. The optical distribution networks (ODNs) account for 70% of the total investments in deploying PONs. Therefore, it is crucial for the NG- PON evolution to be compatible with the deployed networks such as GPON.
GPON delivers data rates of 2.4Gbps downstream and 1.2Gbps upstream. For satisfying high-bandwidth demands NG- PON2 standard G.689 was established by ITU-T. A time and wavelength division multiplexing approach (TWDM) was selected, bundling multiple wavelengths in the downstream and upstream directions. The overall bandwidth can therefore be increased to 40Gbps
downstream/10Gbps upstream using four channel/wavelengths at 10/2.5Gbps rates. The optical distribution networks (ODNs) account for 70% of the total investments in deploying PONs. Therefore, it is crucial for the NG-PON evolution to be compatible with the deployed networks such as GPON. With NG-PON2 using multiple wavelengths, there is a need for tunable transceivers in the optical
DECEMBER 2024 Volume 46 No.4
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