It had in the past been estimated that major European cellular operators might be able to provide 500MB/user/month without another wave of network upgrades; if this calculation is at all typical, it looks like there is a substantial risk of an ”iPlayer event” hitting cellular in the near future. Recap: when the BBC placed vast amounts of its content on the Internet through its iPlayer service, DSL traffic in the UK spiked; or rather, it didn’t spike, the trend shifted permanently upwards.

That, of course, is much more worrying; because the marginal costs are set by the capacity needed to handle the peaks, a rise in average traffic means a boost to costs multiplied by the peak/mean ratio. An aggravating factor is the pricing structure for BT Wholesale backhaul service - the commits are 155Mbits/s, so if the new peak demand just exceeded your existing commit, you needed to buy a whole 155Mbits/s pipe. The impact on the UK unbundling/bitstream ISPs has been serious and the sector remains in a critical condition.

Traditionally, a mobile base station was provisioned with 2 E-1 leased lines, 2×2 Mbit/s capacity. There are 2,419,200 seconds in a month. Multiplied by 4, that’s 9,676,800 Mbits in a month. Divide by 8 to convert to MB, 1,181GB/1.15TB a month. Which means that a typical cell site could support at the most 1,832 users’ activity, or quite a lot less when you consider the peak/mean issue - typical values are 4:1 for GSM voice (458 users), but as high as 50:1 for IP (36!). Clearly, those operators who have had the foresight to pull fibre to the base stations and, especially, to acquire their own infrastructure will be at a major advantage. (Thanks to the commenter who corrected a mistake in the calculation.)

Click here to read more about the iPlayer, the iPhone, Iliad, and the infrastructure consequences of user interfaces