Verizon says it is ready to advance to final lab trials of NG-PON2 equipment before deciding on a supplier. A team of Ericsson and Calix will face off against ADTRAN in Verizon's Waltham, MA, facility. A Verizon source said the results of the trials will determine whether the service provider selects one or both competitors to deliver NG-PON2 optical line terminals (OLTs) and optical network terminals (ONTs) ahead of an expected 2017 deployment start.
Verizon has selected NG-PON2 as its follow-on fiber-optic broadband access technology to GPON. The architecture uses a time- and wavelength-division multiplexing (TWDM-PON) scheme to support transmission of four wavelengths per fiber; each wavelength can support symmetrical 10 Gbps services (see "The Bright Future of TWDM-PON and Wavelength Unbundling"). Future versions of the technology are expected to provide even higher capacity, via more wavelengths, greater transmission rates, or both.
According to Vincent O'Byrne, director of network planning for Verizon, the service provider favors the architecture over alternatives such as the earlier XG-PON1 because of its potential flexibility and scalability (see "XG-PON1 10G GPON may not be enough for Verizon").
Verizon has long had an interest in NG-PON2. It issued a request for information (RFI) surrounding the state of NG-PON2 development two years ago and conducted field tests of the technology last year (see and "Verizon tests NG-PON2 FTTP network ahead of RFP"). Satisfied with what it had discovered, the company issued a request for proposals (RFP) last October, which closed early this year.
O'Byrne said six companies responded to the RFP. He declined to identify them beyond the remaining competitors.
Overall, O'Byrne said that Verizon will evaluate the Ericsson/Calix and ADTRAN offerings based on such factors as their performance, roadmap toward future capabilities, and compatibility with existing systems. He highlighted several performance issues that will receive close scrutiny:
Wavelength tunability: As the NG-PON2 architecture supports multiple wavelengths, the receiver at the ONT will have to tune among them to select the appropriate transmission. Tunability also is important for fault reconciliation. So tuning speed will be critical; the closer to 50 msec, the better. While some vendors have touted the ability of NG-PON2 to enable operators to separate business and residential services on separate wavelengths, O'Byrne said he could foresee carrying residential and business services on the same wavelength, particularly in the presence of a network fault or where bandwidth requirements don't demand separate lambdas. Verizon also will leverage tunability for load balancing, he said.
Scalability: Verizon expects to use NG-PON2 for the foreseeable future. Therefore, O'Byrne says he's interested in the ability to combine wavelength transmissions through a form of bonding. Thus, an ONT could accept transmissions greater than 10 Gbps. The ITU-T is working on specifications for this function.
Interoperability: Verizon wants its NG-PON2 OLTs to work with ONTs from multiple vendors. O'Byrne says Verizon does not want to repeat its experiences with GPON, in which it occasionally has found it difficult to meet custom requirements via purpose-built ONTs because their GPON OLTs won't support them. Along these lines, Verizon will expect its NG-PON2 OLT to work with a new open ONU management and control interface (OMCI) it is creating. Similarly, the operator would like to see NG-PON2 OLTs from different vendors work together more seamlessly than GPON OLTs do now.
O'Byrne says the lab trials should last approximately three months. He said he's unsure whether field trials will follow; having conducted field trials already, additional field trails would only be necessary if Verizon has unanswered questions at the end of the lab trials, he said.
O'Byrne declined to state whether Verizon hopes to go with both suppliers or just one. He noted that the company previously has selected a pair of vendors for both BPON and GPON equipment.
Verizon will focus its initial NG-PON2 deployments on support of business services. O'Byrne noted that businesses would more readily use such bandwidth. He also said the first round of NG-PON2 technology likely would be too expensive to meet residential service business models.