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General

New technology puts choice for FTTH or LTE in sharper focus

Monday 8 December 2014 | 16:02 CET | Background

The development of faster broadband technology, both fixed and wireless, is relentless. G.fast has now become a formal standard, building on VDSL, while Alcatel-Lucent has launched its own complementary technology, Vplus. LTE technology has also set a new speed record of 4.1 Gbps. What are the implications of the new advancements?

A brief summary of the latest milestones:
  • G.fast. The ITU has approved the final version of the standard, ITU-T G.9701. This technology uses a large amount of spectrum in order to realise a high bit rate. The reach is limited to a few hundred meters, and the performance erodes quickly at longer distances. This means the fibre backhaul must be brought closer to subscriber ('fibre to the distribution point', FTTdp).
  • Vplus. Alcatel-Lucent is launching this as an addition to G.fast and replacement of the VDSL2 standard. This holds up better with increasing distance (length of the copper loop) than G.fast. At very short distances (up to 200m), G.fast still is better. It uses more spectrum than VDSL2, so the performance is always at least as good as VDSL2. For distances of 200 to 500 meters to the fibre connection, the performance is better than both VDSL2 and G.fast.
  • Nokia, in cooperation with China Mobile and Ooredoo, has demonstrated a speed of 4.1 Gbps over LTE. It used 10 carriers of in total 200 MHz, of both FDD (paired) and TDD (unpaired) spectrum.

On paper, Vplus offers a solid performance, expanding nicely on VDSL2. The main disadvantages of G.fast (as well as VDSL2 and Vplus) are financial: the fibre must be brought closer to the subscriber. The equipment is also costly, driving up the cost of this kind of copper technology to several hundred euros per customer. This raises the question would it not be better to build that last bit of connection with fibre ('fibre to the home', FTTH). This creates nearly unlimited bandwidth (dependent only on the active equipment). The downside here is of course the extra cost.

At first glance, LTE appears the preferred technology. In terms of performance, it leaves copper far behind, and it has the advantage of being quickly deployed and delivered to the customer. At the same time, mobile is a 'shared' technology (the same as cable and GPON). Subscribers on the same base station share the amount of bandwidth available, so the performance is strongly dependent on the number of users. With normal internet traffic, this is not usually a problem, as traffic occurs in peaks, but when it comes to streaming video, then every user needs a steady amount of bandwidth throughout their session (LTE Broadcast offers operators an answer for this). Another limitation of Nokia's technology is the large amount of spectrum needed. On a practical level, using so many bands will only be possible once 5G is deployed.

Conclusion

We know fixed connections to be robust, with Wi-Fi the extension that slows the connection down. Wi-Fi can suffer from interference and obstacles such as thick walls. Mobile connections are much less reliable (the performance varies widely) and also have problems with walls, especially when using higher frequencies (over 1 GHz).

The latest developments sharpen the focus of the technology debate. Is FTTH needed, or is G.fast/Vplus in combination with FTTdp enough? How much does the answer to this question depend on the growth expectations for data traffic? Can LTE compete with these technologies and serve as a replacement? If not, are there possible situations (eg, rural areas) where that could be the case?

Ongoing consolidation is creating very large-scale telecom companies. Those with stock market listings are very much focused on the near term. This leads to conservative choices, such as copper technology. In principle, this creates room for challengers to differentiate themselves by taking different choices, whether that be FTTH (such as Google Fiber in the US) or LTE as a replacement for fixed lines. 



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