Even when FTTH is available, not all customers want it. Operators report some customers cancel installation when the technician says holes need to be drilled in the wall. In this situation VDSL2 Vectoring or G.fast would be an alternative.
Combining VDSL2 vectoring, G.fast and fibre allows operators to mix deployment models to achieve maximum coverage at the lowest cost. Instead of digging up the last mile to lay fibre into the home, operators lay fibre to the most economical point. This pragmatic hybrid copper/fibre access model will enable service providers to gradually transition to an all fibre network while delivering more broadband to more people - quickly and affordably.
For service providers with mature all-fibre networks, increasing speed is no longer the main driver. The driver now is unlocking the full potential of fibre, to increase capacity and shorten payback time. For many operators the goal is to have one flexible network that can support many revenue-generating services, make efficient use of existing assets and cut the cost of deploying mass market broadband.
The fibre network evolution roadmap is based on two stages: NG-PON1 and NG-PON2. The former, built on XG-PON1 technology, is readily available and offers 10 Gbps downstream and 2.5 Gbps upstream. But so far there is no traction in the market, as current GPON networks provide plenty of bandwidth. Instead, the strategy of most operators is to evolve to NG-PON2, which offers not only higher speeds, but added operational benefits and revenue potential. The first pilot deployments are expected in 2015.
Among several technology options for NG-PON2, the FSAN standardization organization has chosen Time Wavelength Division Multiplexing PON (TWDM-PON). TWDM-PON as the most efficient way to upgrade a fibre network designed to connect residential users, businesses, and nodes in fixed and mobile networks. The TWDM standard specifies up to 8 wavelengths.
A typical implementation will use 4 wavelengths at first, delivering a capacity of up to 40 Gbps (symmetrical) - 16 times more than today's widely deployed GPON networks. In addition to providing higher capacity and flexibility, TWDM-PON preserves the operators' current PON investments and allows them to reuse their most expensive component - the outside plant.
Under the mantle of NG-PON2, TWDM-PON will push the evolution of FTTH to a multi-broadband service platform. Operators will be able to overlay four or more PONs on the same fibre plant to deliver greater speed, service diversity and network sharing. It will, for example, be possible to overlay a residential network with a business network along with separate networks to provide mobile backhaul for small cells (Figure 2).
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