Nielsen’s Law of Internet Bandwidth states that a high-end user’s connection speed grows by 50 percent each year, doubling roughly every 21 months. That suggests a top-end internet access connection in 2025 will offer 10 Gbps speeds in the downstream.
But it is reasonable to assume Nielsen’s growth rates cannot continue forever, as 50 percent compounded growth without end has some physical limits (time, physics, cost, demand, substitutes). At some point, as was true with personal computer processors, parallel processing becomes the method for boosting performance, while raw processing itself loses relevance as a product differentiator.
In the consumer internet access space, that suggests both new ways of supplying bandwidth, less value produced by ever-increasing speed offers and a shift to other forms of value.
Nielsen’s Law only predicts the top speed available for purchase, however, not the average or typical speed a consumer might buy. It has taken quite some time for customer uptake of gigabit internet access services to reach as much as eight percent share of total, for example.
Keep in mind that the first U.S. gigabit services began commercialization in 2013. It has taken seven years for adoption to reach eight percent of the installed base, in part because that grade of service is not universally available in the U.S. market, for example.
Cloonan's Curve provides a way of estimating bandwidth speeds purchased by cable modem customers, in relation to the headline speed (Nielsen rate). Most customers do not typically buy the fastest-available service, as that also is typically the most-expensive tier of service. Instead, they tend to buy the mid-level service.
The caveat is that Cloonan’s Curve obviously does not apply to service providers that sell only a single tier of service, at the advertised headline rate (“gigabit only,” for example).
This illustration of downstream bandwidth plans actually purchased by customers suggests that although both Nielsen and Cloonan rates increase at about 50 percent per year, most customers buy services that offer six times to 20 times less speed than the fastest-available service tier.
Think of the fastest tier of service (1 Gbps, for example) as the “billboard tier” that is featured in service provider advertising as the “speeds as fast as X” rate. Then consider the “common or popular tiers” as those in the middle of the offered speed ranges. Then there is an “economy tier” for customers with light usage patterns, limited app requirements or willingness to pay profiles.
That has implications for network planning, bandwidth upgrades and marketing. Internet service providers can advertise the headline speed knowing that a small percentage of customers are going to buy it.
Networks obviously must be designed to deliver the headline rate. But total bandwidth consumption, which affects the capabilities of the rest of the network, does not assume that every customer buys the headline rate service. Instead, the variable portions of the network can be designed on the assumption that most customers will, in fact, not buy the headline service.
Since speed and data consumption tend to be correlated, that affects capacity planning for backhaul, for example. Simply, the Cloonan Curve informs thinking about how much capacity must grow to support the actual mix of demand from the full set of customers, based on their actual buying patterns.
That is important to match capital investment as much as possible to the variable demands placed on the network by various customer groups.
For a cable ISP, there are other implications. At some point, it will make sense to migrate the highest-usage customers--often identical with those buying the headline service--off the hybrid fiber coax network and onto a parallel access network using fiber to the home instead.
It is common to find that the top one percent of customers generate as much as 15 percent of total network usage, for example. So moving those customers off the core network frees up considerable capacity for the rest of the customers, 90 percent of whom might be supported on the legacy access network.
That allows a longer useful life for the HFC network, as most customers will continue to buy the popular and economy tiers of service that still can be supported using HFC.
Nielsen’s Law does not account for upstream bandwidth, however. Upstream capacity tends to grow at about half the rate of downstream bandwidth, or about 25 percent per year.
Customer behavior also varies. On cable networks, the heaviest users (one percent) of customers generate as much as 47 percent of upstream bandwidth. And it often is the case that 80 percent of total upstream capacity demand is generated by just 10 percent of total users.
ISPs using telecom platforms also will confront that same general issue of bandwidth growth, and the differential demand for tiers of service. Fiber to home platforms keep increasing performance as well, and some suggest future performance will be boosted economically based on use in the local loop of components originally commercialized to support data center optics.
That is why 25 Gbps passive optical networks initially deployed for business-to-business applications in the local loop will be powered by commercial availability of data center optical components, Nokia argues. Commercialization for B2B use cases should then be leveraged for B2C applications as well.
Nielsen’s Law and Cloonan’s Curve also suggest the potential limits of HFC as a platform. If consumer usage patterns do not change; if ISP usage policies do not change; if app usage patterns do not change; if pricing patterns do not change, then there is a point in time where HFC fails to support cable operator business models.
The point of overlaying FTTH for the heaviest users is that, all other things being equal, the useful life of HFC is extended, with a more-gradual shift of cable platforms to FTTH over time.
The issue is to avoid the stranded capital problem and immediate higher capital investment implications of a jump cut to FTTH. That would be as difficult for cable operators has it has proven to be for telcos.
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