DEMANDING MARKETS - JOHN WILLIAMSON
Gigabit PONs tune up for demanding markets
Various formats of gigabit passive optical networks are generating a lot of interest and sales in traffic-heavy markets across the globe, whether the driver is HDTV or overburdened data center interconnects, John Williamson reports.
market drivers for NG-PON2 in terms of extra capacities required. Mersh reckons the actual and forecast growth of video and HDTV is an important consideration. His colleague, BBF’s Director of Strategic Planning, Mark Fishburn, puts the data center interconnect at the centre of the equation. Meantime, Geoff Burke, Senior Director of Corporate Marketing at Calix, believes symmetrical business services and mobile backhaul will fuel demand for NG-PON2 bandwidth. And none of these suggestions excludes any of the others. However, it has been argued that NG-PON2’s flexibility could be more of a draw than its increased bandwidth. “It’s a multiple wavelength solution that provides a lot more flexibility,” observes Burke. “This flexibility has the potential to open up a number of different avenues for expanding the market.” For its part, the FSAN in its literature has notes that, “TWDM- PON does not excel in any one performance metric but provides a good balance of attributes for mass market residential broadband applications. It offers good performance with reasonable cost, using components mature enough to meet the NG-PON2 timescales.” Let’s work together But for the NG-PON2 opportunity to really take off, a number of prerequisites must be met. Equipment interoperability is crucial for service providers both in terms of them cost-effectively building multi-vendor networks and shortening times-to-market for new services. However, for a number of reasons adherence to a standard does not guarantee that products
(HDTV), mobile backhaul and wireless Local Area Network (WLAN) coverage extension. According to Robin Mersh, CEO of the Broadband Forum (BBF), the particular ambitions and circumstances of particular service providers will influence the take-up of technology such as XG-PON1 as opposed to their plumping for the faster NG-PON2. “It’s a question of if you have to move fast versus if you have a little more leeway,” he reasons. “Added to this, if everyone knows that the next version is coming up, then it’s not surprising that some will wait.” NG-PON2 readies for the big time And the waiting for NG-PON2 looks to be ending, with certain products already announced by the like of contractors such as Adtran, Alcatel-Lucent, Calix Inc and Huawei, and trials reportedly carried out by service providers in Asia, Europe and North America. Propelled along by the efforts of the Full Service Access Network (FSAN) interest group and the ITU-T standards organisation, NG-PON2 is standardised as the G.989 series. NG-PON2’s primary technology is Time and Wavelength Division Multiplexing, with up to eight Point-to-Point WDM overlay channels. The basic deliverable data rate capability of the multi-wavelength access standard is up to 40 Gbits/s downstream (4 x 10 Gbits/s on different wavelengths on the same fibre) and up to 10 Gbits/s upstream, with a doubling to 80 Gbits/s and 20 Gbits/s respectively in extended iterations. Symmetrical services can also be deployed. There is some debate about what constitutes the main
from different vendors will work together. This underscores the importance for service providers of an internationally established and recognised G-PON interoperability certification process. The most prominent of these is the BBF’s BBF.247 G-PON Optical Network Unit (ONU) Certification Program. In that certification is currently open to XG-PON1 products, and the expectation is that XG-PON1 certified ONUs will be available “very soon”. BBF laboratory test plans are also evolving to include NG-PON2. And coming down the turnpike… Although these are early days in the commercialisation process of NG-PON2, there is some industry consensus that the technology could significantly boost the ongoing migration of fibre to the network edge. For Mersh the seemingly unstoppable advance of fibre towards the end user and the consumer is one of the defining characteristics of the contemporary networking business. In this context, Burke believes advances in high speed copper technologies such as Very-high- bitrate Digital Subscriber Line 2 (VDSL2) and G.fast access to subscriber terminals (G.fast) will be very complementary to NG-PON2. In general he reckons improved copper technologies have the potential to widen the appeal of true fibre connectivity, and act as a stepping stone to full fibre. In particular he cites G.fast installations serving Multiple Dwelling Units (MDUs) that require higher backhaul speeds than today’s 2.5 G-PON or point-to-point Gigabit Ethernet can provide.
John Williamson O ne of the undoubted success stories of the fibre-based broadband access market is the Gigabit Passive Optical Network (G-PON). According to a Broadbandtrends LLC estimate, the value of global G-PON systems sales hit nearly $5 billion in 2014. But while demand for the 2.5 Gbits/s downstream/1.25 Gbits/s upstream technology is likely to remain buoyant for the medium term, newer applications and changing market dynamics have stoked demand for higher speed G-PON solutions. Into the breach have stepped print screen. Next generation Standardised in 2010 according to the ITU G.987 Series Recommendation, the XG-PON1 protocol is based on a Time Division Multiplexing-PON (TDM- PON) architecture. Delivering 10 Gbits/s of shared downstream bandwidth and 2.5 Gbits/s of upstream bandwidth, XG-PON1 is designed to be compatible with existing access networks and hardware. XG-PON1 has made a showing in some markets – notably Asia. Its proponents say it is a suitable candidate for a number of applications, including the provision of higher speed residential and SOHO/small business broadband access, the delivery of High-Definition TV
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ISSUE 5 | Q3 2015
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