The recent report by Analysys Mason for OFCOM ("Fibre capacity limitations in access networks") shows again that there are some important path dependencies in the choice of fibre plant architectures for access networks. The main stream press focuses on the speed projections but there is a lot more to enjoy.
I would add: the one architecture and approach that gives you the highest penetration over the lifespan is by far the most interesting one. Unbundling and flexibility of technology increases penetration so it is a factor you should be more interested in than bandwidth scalability.
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In a presentation in November in the UK ("Fibre to Britain") I have showed these slides to demonstrate the choices.
Unfortunately Analysys Mason limits their view (as seen so often) to IP traffic : the myopic view of pure Internet afficionados forgetting there is more than data packets, like linear RF. They also miss the opportunity of "Lambda to the Home".
Nevertheless they make the same point: architecture choices create path dependencies.
Each FTTH technology has an upgrade path to support higher capacity for the next five years. However, the fact that TDM GPON solutions require customer premises equipment to operate at a much higher bandwidth than that required for each individual customer, may limit how far it can be upgraded in the medium to long term, especially as the customer premises environment can be challenging. For example the temperature at the customer premises can fluctuate, whereas premises designed to host long-haul network equipment are air conditioned, thereby minimising temperature fluctuation.
The first observation is that more evolution of enabling technologies is required for PON generations than for PTP architecture, which in a way, makes PTP a less risky technology to invest in. In addition, due to the greater bandwidth scalability of PTP systems, the expected life cycle of each generation of PTP is likely to be longer than that associated with TDM PON. This is an important result, as it indicates that operators will have a longer time to get return on their investment with a PTP architecture compared to a TDM PON architecture, despite a slightly more expensive initial deployment costs (PTP are currently 19% more expensive to deploy than TDM PON systems, mainly due to the additional fibre, and therefore duct infrastructure required).
So from this analysis, we do not believe that there will be any significant barriers in the evolution of FTTH systems capacity. However, we believe the bottlenecks maybe in the upgrade of one generation of FTTH systems to the next, especially if an operator decide to depart from a TDM PON infrastructure to a WDM PON infrastructure. In the UK for example, if, in the medium term, Openreach was to upgrade its GPON network to a WDM PON network, it would need to prepare for it today by allowing for extra space in the splitter site to be accommodate extra equipment (wavelength demultiplexers for WDM PON).
Indeed.
Not a bad report, just missed some obvious points.
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