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Wednesday, March 17, 2010

WiFi offload will not always win out over femtocells

There seems to be an undercurrent of skepticism about some of the usage scenarios for femtos - in particular, the notion of why anyone should bother with femto offload, if an increasing set of devices all have WiFi anyway.

The Femto Forum has released a study on femto/WiFi coexistence which highlights some reasons it sees for combined deployment, but I think a couple of additional ideas are also useful.

One important factor is the difference between laptop PCs and smartphones:

- In a 3G-enabled laptop, WiFi is almost always switched on, but 3G is usually only on part of the time (not least because most users will only plug in the dongle when needed)
- In a 3G-enabled smartphone, 3G is almost always switched on, but WiFi is usually only on part of the time

And for both, 3G (or at least data access on the phone) is likely to be switched off when roaming internationally.

This will mean that laptop 3G data offload is probably best done via WiFi, but smartphones may be more femto-centric - especially as smartphones are more likely to have operator-branded services that make it advantageous to keep the traffic on-net. Laptop data is 99.999% straight to and from the web, with almost zero operator value-add, so it makes sense to dump it to the cheapest connection as often as possible.

But even that overlooks yet more layers of subtlety in terms of user behaviour.

I've been using an iPhone 3GS the last few weeks, and the battery life is atrocious. So I've done the usual power-management tricks of turning down screen brightness, turning off GPS, and manually switching off WiFi when I leave my house, only switching it back on when I know I have access to free WiFi elsewhere such as a hotel or certain cafes.

So although it's not hitting the cellular network all the time, and my home WiFi certainly takes quite a lot of the strain, it's certainly not able to offload everywhere where the operator might like, or might have WiFi offload deals with hotspot providers.

My two local branches of Starbucks gives me a real sense of the paradox:

- I know I can get access to the BT Openzone WiFi for free with my Vodafone iPhone contract.... but I've got the WiFi switched off by default, it requires me to do some sort of registration process with my account number (which is at home) and 3G coverage works fine in both cafes, so I don't bother.
- For my 3UK dongle for my laptop, one cafe has good HSPA signal and the other is lousy. In the one which is lousy, I use the WiFi, which I can again get for free with a Starbucks loyalty card (there's no offload deal in place with 3). In the other, I always use the dongle as the WiFi access controller seems to have a 20-second setup time before hitting the splash page, and another 20 seconds before I get authenticated. And if I'm using the 3G, I'll switch off WiFi to save battery.

Now re-imagine these scenarios with a femtocell viewpoint. At home, I'd probably still use WiFi rather than a femto, as I'd expect it to be faster - and some pretty innocuous websites I visit fall foul of Vodafone's over-zealous content filter and get blocked. VoIP provider Fring's website is censored, for example. I can't be bothered to phone up for "adult access" permission, and anyway I'm sure there are other things in the T's and C's about fair usage that I can obviously ignore when I'm on my own WiFi. I obviously never use the 3UK dongle when I'm at home within range of WiFi, as my laptop just connects and authenticates immediately and without extra intervention.

The cafes are different - if there was a Vodafone femto and the iPhone switched onto it, I'd probably notice an improved performance and likely lower power consumption. Same thing with the 3UK dongle in the branch where I currently don't have coverage - I'd probably switch back from the WiFi with its more-cumbersome login process with passwords and splash screens.

But you've probably already spotted the problem - does Starbucks want 4 or 5 femtos in every branch, from different operators? Who would pay for them? The cafes already have "sufficient" connectivity for everyone with WiFi - it's unlikely to want to bear the cost of just making it marginally more convenient for a select group of its customers.

The point here is that the neat idea of a monoculture of WiFi offload everywhere, or 3G offload to femtocells do not fit with the annoying peculiarities of consumer behaviour. People very quickly find the most convenient / cheapest / fastest / best battery-saving strategies for their personal circumstances. It's very difficult for operators wanting to conduct offload to work their way around those optimisations - unless they use either very smart connection-management software, or very brute-force ways of ignoring the subtleties.

One other thing occurs to me: I wonder if it's possible to get the presence of a WiFi SSID to trigger a device to switch on 3G and look for a femto in that location. Or for the presence of a specific femto (on any carrier's network) to trigger a client to power up smartphone WiFi if it's switched off, and use that instead.


Mo said...

“ I wonder if it's possible to get the presence of a WiFi SSID”

Theoretically anything’s possible, of course, but yes, I think this would be.

As far as I know, BSSIDs are EUI-64s, so a BSSID lying in the “locally administered” EUI range having a special format is perfectly permissible.

Essentially, off the top of my head, start with all-zeroes. Set the second bit of the most-significant octet to indicate “locally administered”; set the fourth and fifth octets to 0xFF and 0xFE respectively (so the BSSID starts with 02:00:00:FF:FE:…). Finally, put the MCC and MNC in the least-significant octets.

So, for Vodafone UK you have a BSSID of 02:00:00:FF:FE:00:EA:0F.

Broadcast this BSSID with either a hidden or placeholder SSID (hidden would be preferable, for obvious reasons) and devices should be able to spot it.

There are probably better ways. This relies on a somewhat stretched definition of “locally-administered”, after all. It also assumes the MNC will never exceed 255, which I don’t think is guaranteed (US?). You could account for that, though.

Gabriel Brown said...

Battery life isn't impacted hugely by leaving WiFi on in my experience. The radio is dormant most of the time.

The main problem is if you leave IM accounts and chat sessions always-on when connected over 3G.

One problem I have found is that my current device (N900) seeks out and auto attaches to WiFi networks. That's fine (good, even) apart from when the WiFi performance is worse than 3G. This happens at work quite a bit.

Anonymous said...

Who thinks that femtos will ever be anything more than a niche product? Will the price ever be low enough to allow a large scale deployment? Who wants one in their house? (I don't). Can we dispense with the silly name?

Dean Bubley said...

Thanks for the responses.

Mo - thanks, that's quite a lot to get my head around!

Gabriel - it's quite device-dependent I find. The iPhone doesn't do IM in the background and is very good about shutting off 3G (hence the signalling load....) but eats battery for the screen & whatever else. Push notifications might fry it.

The point is though that a user thinks "battery life is awful", and switches off as much as possible, perhaps not then switching stuff back on to see which is the biggest "win". I have no idea whether I'm typical in being prepared to toggle WiFi on/off once or twice a day, or if for most people they'll never change it, or switch it more frequently.

You N900 / WiFi issue just underlies the point - user behaviour & preferences are extremely hard to predict as they're so geared to individual experience and context.

Anonymous - femtos (or at least picos) *have* to become massmarket if cellular networks are going to continue to grow in capacity. There's simply not enough spectrum & macrocell sites.

Why the problem with having one in the house? They're not that ugly & can be hidden away like the WiFi router. Not hugely power-consumptive either. Sure, having 3 or 4, for each operator you have a device from, would be a pain though.

The pricing curve is what you'd expect for a product that's only just been launched commercially. A lot of people seemed to latch onto early overhyped and overoptimistic forecasts - I'd question the hockey-stick merchants (my competitors....) rather than the underlying concept.

Some of us have been more realistic for quite some time... my predictions from 2 years ago don't look bad:

Gabriel Brown said...

Right. Device-dependent is a big part of it. One interesting avenue (not specifically related to femtocell) is for a client to manage WiFi for you based on your own preferences, or your operator's policy.

Anonymous said...

You can get a femto from Vodafone for 50 pounds. How much cheaper do you want?

Dean Bubley said...

I suspect the answer depends on how it's positioned & the target segment. At the moment Vodafone is advocating it as a serious tool for "professional" mobile users (hence worth paying for), or as an option for those desperate for any sort of coverage.

But I suspect that if it's main reason is for *offload* for the operator's operational reasons, rather than a direct consumer benefit, then £zero is probably a starting point.

And given it's using "the customer's pipe" for free, there's an argument for it to be negative pricing with the consumer getting a per-GB bounty for offload. Especially if Telefonica launches one, given its CEO's recent comments about Net Neutrality.

martinwhxx said...

Why is WiFi offload better than using a femtocell for offload?

1. WiFi usage doesn't come out of the 'MNO data bundle'.

2. Its architecturally better. AIUI, the Internet is about peer-connected IP devices not routing my IP traffic through some MNO-controlled proxied port-blocked age-filtered centrally-controlled DPI-ed SGSN/content adaptation/content filtering monstrosity.

3. Having a femtocell disincentivises users from changing networks, porting to another operator for a better deal. How can that be good for consumers?

4. As already mentioned, most households are multi-network and most femtocells aren't.

5. Devices like the iPhone and the Nexus One make WiFi offload completely painless. The iPhone was the first device to implement this truly transparent offload mechanism, making all previous attempts by Nokia and others look like primitive to the point of being useless. Ergo, today's and tomorrow's devices make WiFi offload easy.

6. WiFi offload is better for the MNO because they don't need to sell and support femtocells and yet WiFi still achieves the objective of significantly reducing network load by taking traffic off the macro network.

The only use case for femtocells is for people with poor or no coverage on any of the macro networks 2G RANs. There aren't many people who have no 2G coverage on any network but for them the femtocell will enable them to send/receive text messages and make/receive calls over the MNO's network, and for them that's probably a wonderful breakthrough.

For the rest of us femtocells represent the kind of MNO lock-in (they call it 'stickyness', yuck) that most people are desperate to avoid.

Anonymous said...

How much cheaper than 50 quid do I want?!? Try free, then I *might* consider getting one, if you can show me how it's actually going to be of any use to me.

Presumably that 50 quid is still a subsidised price (I believe that femto CPE are still of the order of $100 or more) so how on earth there is a business case for these things I don't know.

Yes, I know that some people are going to find them useful but I really question whether there is any substantial market for these at all.

Anonymous said...

"This will mean that laptop 3G data offload is probably best done via WiFi, but smartphones may be more femto-centric - especially as smartphones are more likely to have operator-branded services that make it advantageous to keep the traffic on-net."

By using SIM authentication EAP SIM/AKA or WISPr 1.0/2.0 the MNO can let the subscriber authenticate and establish an IPSec VPN back to the MNO packet data core. This allows operator to continue to offer home data services and most importantly maintain control of the subscriber (rather than simply booting them off into public internet domain).

Dean Bubley said...

Anonymous - operators *want* to boot a lot of traffic off into the Internet domain, not push it all through the core network and back out the other side to the web. They want the metadata about internet use and also any hosted services, but it's pointless buying more GGSNs when a lot of dat could be offloaded locally at the DSLAM or wherever. Hence the work on selective IP offload in Release 10

nick said...

Hi Dean,

Regarding auto switching from 3G-to-Wifi (or back again), there are apps available to do this for you based on time/date/localisation - at least there is one for my HTC Desire.

Eg, I have mine set up to swap to wifi when the (cell tower based) localisation tells it is within range of home. So it isn't too much of a stretch to imagine this sort of functionality enabled by starbucks etc.

I guess this doesn't need operators involvement anymore as it can be application layer.