next generation GPON (NG-GPON)

The International Telecommunication Union(ITU) has established Next-Generation PON( NG-PON) standards for Next-Generation GPON (NG-GPON) via the Full Service Access Network ( FSAN) working group. There are two standards: XG-PON1 or NG-PON1, standardized under ITU G.987 operates with asymmetric transmission and a data rate of 10 Gbit/s downstream and 2.5 Gbit/s upstream. The second is TWDM-PON, which uses a combined multiplexing technique.

XG-PON1 supports the coexistence of Gigabit-PON on the same Optical Distribution Network( ODN) and allows the subscriber to upgrade in stages. Downstream data rates are 10 Gbps, while upstream rates are 2.5 Gbps or 5 Gbps. The upgrade to NG-PON2 has data rates of 40 Gbit/s and 10 Gbit/s upstream and uses time division multiplexing(TDM). For the 40 Gbit/s, wavelength division multiplexing(WDM) in the form of CWDM or DWDM is used as the second technology.

The TWDM-PON standard combines the wavelength division multiplexing of WDM-PON with the technique used in GPONs, where multiple subscribers are served over one wavelength. TWDM-PON offers four or more wavelengths per optical fiber over which the data can be transmitted symmetrically or asymmetrically.