The wrong sort of WiFi
A decade ago WiFi was an irrelevance to mobile network operators. There has been sporadic efforts by some to deliver a “mobility” story through WiFi hot spots but their popularity has been limited. The wide area mobile networks have always had the upper hand. They have been able to deliver what most people have wanted, provide it far more conveniently and comprehensively at steadily reducing prices. The mobile network operators have also largely controlled the direction of the mobile phone ecosystem (through mobile phone subsidies) and if something does not find its way onto the mobile eco-system road map… it never goes mainstream …a reason WiMax has become a global non-event and WiFi took its time to appear on mobile phones.
Simple arithmetic a decade or so ago showed the absurdity of WiFi trying to rival the mobile networks for coverage. WiFi depends upon low power and short ranges not to self destruct from mutual interference. Typically WiFi has a range of 100m (less if thick walls get in the way). This means that to replicate the coverage of a mobile cell with a radius of say 1 km required 100 WiFi points…each fairly precisely located, protected from the elements and wired back to the telecommunications network. The 1 km (or more) radius mobile cell has (until recently) been the better technical and economic solution.
There was a tinge of anxiety amongst the mobile network operators a few years ago when some of the main stream hand set suppliers like Nokia started to build WiFi into high end mobile phones and Skype was catching the media attention with free telephone calls. Could WiFi on the mobile phone be a Trojan horse that might lead to a collapse of mobile telephone revenues? A moment of reflection and the anxiety soon passed. Bundles of minutes per month saw off the threat. Who would want to bother with Skype on mobile phones when the more generous bundles of paid-for mobile minutes had still not be used up by the end of the month?
Then along came the mass take-up of broadband on the fixed networks… with an ever rising volume of data traffic and data speeds that the mobile operators found their much vaunted 3G technology and spectrum costing billions was simply unable to handle. At that point the old cherished vision of mobile networks eventually sweeping away the wire-line networks collapsed in it own absurdity… if 3G was the way it was supposed to happen.
The struggle was back on when, at last, HSPA arrived and started to build some credibility for mobile broadband. The story looked even brighter with 4th generation Long Term Evolution (LTE) technology offering even an more powerful mobile data capacity network engine coming along not far behind.
Was mobile back in the fight to win the battle for the home against fixed wire-line networks?
Sadly for the mobile network operators…the answer is no! The broadband Internet had moved onto video streaming big time…and all the mobile network operators can now see coming towards them is a tsunami of data…for which all the spectrum (current and yet to be acquired) with all the best wide area mobile network technology…will be quite unable to cope with.
Suddenly the relationship between the mobile network operators and WiFi changes. WiFi is now a friend. The more customers could be persuaded to ship data via their home WiFi (now built into all mobile smart phones)…the less investment the mobile network operators have to put into their networks in order to hold up data speeds. The WiFi gets transformed into a personal mobile base station hosted by the customer themselves free of change and who even pays for the backhaul. Into this model also comes the alternative to WiFi…the Femto Cell…which broadly does the same job as WiFi but the data is sucked back to the mobile operator’s data centre rather than the fixed ISP’s.
We now find ourselves at one of those turning points in mobile network history. By the laws of physics the only way mobile connections can be made at super fast access data speeds (10’s if not 100’s of Mb/s) is for there to be very short transmission ranges. There are now four games in town to provide those very short ranges:
- WiFi in the home (using unlicensed radio spectrum and IEEE 802.xx technology),
- Femto Cells (base stations in the home using mobile spectrum and a broadband mobile technology)
- Public mobile radio cells (taking cell splitting to its limit and using mobile spectrum above 1.8 GHz to control the small size of the cells).
- WiFi in public places (using unlicensed spectrum and IEEE 802.xx technology)
Top down (cell splitting) is going to inevitably meet bottom up (aggregating hot spots) over the next 5-10 years and the two are not exactly aligned. To see why it is worth paying another visit to our simple arithmetic.
The top 10 UK cities occupy a physical area of 4375 sq km. Let us look at what would be needed to cover this entire area with WiFi. We will need to take a more realistic view of the range in a heavily built up area…let us say 50m. This leads to a need for 127 WiFi hot spots to cover 1 sq km and therefore around 560,000 to saturate the top 10 UK cities with WiFi coverage.
Now 560,000 WiFi units may seem like a very large number but this number of WiFi units in our top 10 cities already exists…many times over. Why don’t we all just cut out the mobile network operators and run our mobile phones entirely on WiFi?
The answer is that it is the wrong sort of WiFi for such “free” seamless roaming. All the domestic WiFi units have encryption to protect our privacy, most of it is switched on and so this massive free coverage is simply not accessible. The encryption isolates the installed base of WiFi into millions of disconnected tiny islands of coverage.
Some will point out the BT initiative with its imaginative FON Community…whilst this is going in the right direction in creating a mobility story out of WiFi (in fact history may come to acknowledge it as a groundbreaking move), it currently lacks geographic scale and density, the encryption on domestic WiFi units is not as secure as it should be….and more fundamentally it is not aligned with the emerging mobile femto-cell world… a pre-condition for a geographic scale and density breakthrough.
Mobile phone connections on the other hand provide a very high degree of security, the encryption is very very strong and in fact it sits within a well thought through security model based upon the SIM card. The SIM card is the ultimate guarantee that if the security algorithm is ever compromised…it can be upgraded very quickly and cheaply. Sitting alongside this security model is the “location register” necessary to deliver data to people on the move. This provides a significant opportunity for the mobile network operators…if the Femto cell really goes main stream…as a next generation WiFi.
So the future of a seamless super fast mobile broadband depends upon how the top down mobile cell splitting world can be made to dove-tail with the bottom up WiFi hot spot (or Femto Cell) aggregation world…and that future is likely to hinge less on the mobile technology itself (it does not matter if it is WiFi or Femto Cell technology) but more on the cooperative authentication/encryption/location model that gets attached to it
(Note: Since writing this blog things have moved on. There is a growing consensus that an inside-out approach to mobile radio coverage based on WiFi and Femto Cells provides a real prospect for Super High Density Wireless (SHSW) able to deliver 50-100 Mb/s to mobile devices over substantial urban areas…which provides an additional benefit of taking enough traffic off the wide area LTE networks allow edge of cell edge data speeds to rise by a factor of 10…watch this blog space…)