The NG-PON2 standard has yet to be finalised, but that hasn’t stopped ZTE Corp. unveiling what it claims is the world’s first standards compliant time- and wavelength-division multiplex passive optical network (TWDM-PON) prototype at Broadband World Forum 2012 (BBWF) in Amsterdam.
The Full Service Access Network (FSAN) group reached consensus about what the next iteration of PON standards would look like in a meeting in April this year (see Next-generation PON standard adds wavelength division multiplexing). ZTE says it started to develop its first TWDM-PON prototype soon after the standards direction was determined.
The decision to add WDM as an overlay to a TDM-based solution made sense – it is relatively easy to make the equipment backwards compatible with older generations of PON, and is technologically achievable in the expected time frame of the standards development.
ZTE anticipates that GPON and XGPON1 technologies will dominate the market for the next five years. Overlaying other wavelengths using TWDM technology will be a good choice for higher bandwidth requirements in the future, the company says.
“Operators need to be building broadband networks that can evolve flexibly,” said Bei Jinsong, director of ZTE Optical Access Networks. “By overlaying XG-PONs with new wavelengths, the network can gradually upgrade to the bandwidth of NG-PON2 as needed or enable open access based on wavelength paths.”
The central office equipment for the TWDM-PON prototype is ZTE’s unified access platform, the ZXA10 C300, which has been adapted for next-generation PONs. The ZXA10 C300 supports the coexistence and upgrade from one standard to another of GPON, XG-PON1, NG-PON2 and WDM-PtP (point-to-point) on the same platform. The terminals for the TWDM-PON prototype are colourless optical network units (ONUs) with tunable receiver/ transmitter technology.
It should be pointed out that other vendors, including Huawei and Alcatel-Lucent, have also been developing TWDM-PON technology. And Huawei says it demonstrated a 40Gbps TWDM-PON prototype about a year ago.
By Pauline Rigby