The issues with Wi-Fi offloading

Thinking about how my data consumption has changed over the past ten years, it is quite clear that it has increased at an enormous rate. Where ten years ago I was happy with some email and static web pages, today there is video content embedded everywhere, web pages are dynamic, flash based content, streaming, VoIP, attachments, the "Cloud", synching etc, etc. Either consciously or subconsciously this is true for most people and most people want to access all this on the go.

Mobile networks have obviously evolved over the last ten years to cater for this, and the 3GPP is continously working to improve the standard to allow for faster throughputs but more importantly more efficient networks.

Sometimes however either because site density is not adequate, spectrum is not enough, or networks are not configured properly, things come a grinding slow stop which is where "Wi-Fi offloading" comes into play.

As a quick search on Google will show, Wi-Fi offloading is presented as the solution to the problem (the cynic might say this mostly comes from Wi-Fi AP manufacturers) and quite a few operators have either partnered with Wi-Fi network operators or deployed their own networks, in the hope of offloading some traffic from the cellular network.

But does this really work? The biggest problem with Wi-Fi is obviously the fact that it uses shared spectrum. How big a problem is this? Well, a quick scan of the available Wi-Fi networks, as shown in the picture above, will quickly put things into perspective. Sitting at home I could pick out 17 access points of considerable strength, all fighting for the coveted non-overlaping channels. There were even two double bandwidth 802.11n APs spreading themselves over 40MHz. So QoS is obviously an issue here, as all of these uncontrolled access points can appear anywhere, anytime ready to interfere with your "offloading".

So even though Wi-Fi might be available, it is possible that the user experience on the cellular network is much better. This is something people in the industry are aware of and it was interesting to see that for a while even Apple were thinking of switching from Wi-Fi to cellular when things get bad. This screenshot below taken from iOS 6 beta shows this, but for reasons unknown it never made it into the official release (for now).

There are interference mitigation techniques of course, ranging from switching channels (not good if they are all congested) to using various smart antenna techniques (beamforming etc) to try to improve things. I have no personal experience of these, but of course these will come at a cost and with a few caveats.

Furthermore there is always the problem of seemless mobility between Wi-Fi and cellular which even though various solutions have been put forward for it, none have made it into the mainstream yet.

So it seems the only positive aspect of Wi-Fi offloading might be that it is free to use, but then of course that creates another problem for the operator as there is no return in investment.

This then is where the industry has started thinking about "small cells" and another story begins..