ANALYSIS & OPINION: NETWORK DESIGN
using growth models that predicted a gradual increase in bandwidth demand of 30 to 40 per cent over the next three or four years. In comparison, Covid-19 generated 30 to 40 per cent growth almost overnight. Tis has placed unprecedented pressure on providers to maintain service levels and ensure high sustained speeds.
Protect and serve Many operators around the globe have already announced programmes to accelerate fibre investments and upgrades. Governments, too, recognise the need. Tey are acutely aware that almost a billion households in the world have no fixed broadband, and another 500 million have low-speed broadband services unable to support the new normal in digital behaviour. Tese households are vulnerable, and their
lack of connectivity hinders a country’s ability to protect its citizens, its society and its economy. Te challenges are threefold: connecting the unconnected, boosting capacity in underserved communities, and ensuring that even well- served areas do not run out of capacity with this new-normal behaviour. Broadband providers are actively
recalculating for network capacity planning. If we now consider a typical household that may
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be homeworking, e-learning and e-entertaining, we can estimate that the minimum download speed needed is 50Mb/s. Ideally, it is more, but 50Mb/s is really the new minimum. What’s more, households have become video
content creators via Zoom, Webex, MS Teams, etc, so upstream speeds must also increase, to a minimum of 15Mb/s. Tese changes in usage methods necessitate fibre – GPON or XGS-PON – or fibre extension technologies like
G.fast. If that is not enough, the increase in simultaneously-connected devices means providers must consider the capacity and performance of the in-home wifi network as well. Tere is litle point providing hundreds or thousands of megabits to the building, only to create a bandwidth botleneck inside the home. Traditional network design assumes not all
households need bandwidth at the same time, so operators oversubscribe the network. For example, a Gigabit passive optical network (GPON) fibre to the home (FTTH) network with a capacity of 2.5G is used to connect up to 16 or 32 homes with a one Gigabit service.
Outdated approach Tis works because, statistically, it is unlikely that more than two people will need that full Gigabit capacity at the same time. Tat is why
the approach is called statistical multiplexing. Tat approach no longer works. Suddenly, with more households simultaneously connected (and not just at off-peak times), we have lost the overhead capacity that ensured Gigabit services could be delivered. Operators who had plans to upgrade to 10G next-generation PON in three or four years need to do so now. Tere is a knock-on effect in aggregation links and switching capacity, as well. So, where to start? Broadband providers can,
of course, seize the opportunity and monetise the increased demand for higher bandwidth. But governments must react as well. Broadband plans drawn up in the pre-Covid era need updating with fresh targets for coverage and minimum service levels, and new incentives for investment. Subsidies, taxation, private investment incentives, rights-of-way regulations, up to and including government-owned broadband utilities should be considered. To paraphrase Winston Churchill, one should
never waste a good crisis. But in the case of broadband, the impetus for change will actually serve us all well in the event of the next crisis. Let’s not waste it. n
Stefaan Vanhastel is CTO and head of marketing, fixed networks at Nokia
Issue 30 n Winter 2021 n FiBRE SYSTEMS 29
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