By now it's no secret that the rise of smartphones and dongles is driving wireless broadband usage to epic proportions. And it's not going to slow down anytime soon - Cisco Systems' Visual Networking Index estimates that mobile data is growing at a rate of 108% annually, and by many cellco accounts, most of that is being generated by just a fraction of their user base.
The mobile data deluge is, of course, the chief reason cellcos are making plans to evolve to all-IP 4G, but for all the capacity gains and efficiencies to be had from LTE RANs and powerful backhaul solutions using Carrier Ethernet, cellcos are also aware that simply throwing more bandwidth at their smartphone and dongle users is an expensive undertaking that will only get them so far.
Which is why network offload solutions that divert data traffic from the macro network and onto localized broadband connections are generating a lot of interest at the moment. In fact, mobile data offloading will triple in the next five years, according to an ABI Research report. Currently about 16% of mobile data is offloaded from mobile networks today - that will grow to 48% by 2015, during which time data traffic itself will have grown by a factor of 30, meaning that offloaded data will expand 100-fold from current levels, ABI says.
Femtocells and Wi-Fi are the two most visible offload technology options being touted by vendors at the moment, and for a good reason - Informa Telecoms & Media estimates that over 80% of mobile data originates from homes and offices where local broadband connections already exist, and can serve as offload backhaul links for localized access points like Wi-Fi and femtocells.
Such solutions not only promise to ease the strain on macro capacity, says ABI Research practice director Aditya Kaul, but also save cellcos money. "Moving data costs a surprising amount," says Kaul. "Wi-Fi and femtocells in particular do that at a tiny fraction of the per-gigabyte cost of a 3G network." Interestingly, however, there's more to offload than hot spots - in fact, there's more to offload than offload. Cellcos have a number of data traffic management tools at their disposal, from Wi-Fi and femtocells to mobile CDNs (content delivery networks) and media optimization, among other things.
Which ones should cellcos use? As many as necessary, actually.
Femtos: approach with caution
Femtocells are arguably at the top of the offload hype cycle, particularly now that commercial deployments have been announced. Informa says some 13 operators have commercially launched femtocells (compared with only six commercial launches in November), including Vodafone Spain, AT&T, Softbank Mobile and KDDI. China Unicom is trialing femtocells in Beijing. SK Telecom plans to roll out femtos in November.
Still, femtos have been slow to catch on, partly because of uncertain business models and the subsequent marketing challenges, and partly because they're essentially a new network element that cellcos have to be able to integrate and manage.
The latter is crucial, says Steven Hartley, principal analyst of Ovum's mobile practice, because the customer experience has to be as painless and plug-and-play as possible, and it takes a lot of work at the backend to enable that.
"If you want to do anything sophisticated with femtocells besides simply improving indoor voice coverage, you really have to look at how it's going to connect to your network management system, network control system, billing system, mediation system, customer support system, and emergency call system," Hartley says. "How do you manage that on the network, how does it interact with the macro network? Those are important questions when you start thinking about how to evolve this to something more sophisticated like offload."
The distinction between using femtos for coverage vs offload is important, he adds, because offload requires more sophisticated functionality, as well as better interference management. "Deploying femtos for coverage is a niche market and you don't have interference issues to manage. It's more difficult with offload. Vendors talk about self-optimizing femtos that can power up and power down, but if you've got an apartment block and you're serving everyone with a femtos and they all power down, then coverage becomes the area the size of a small conference table. Or it powers up and either interferes with neighbors or with the macro network. So they have to work out how to manage that."
Much of this is why operators are approaching femtos with caution, says Hartley, and why most deployments to date have been primarily aimed at improved coverage rather than offload.
That said, Jai Rajaraman, Asia Pacific senior director for the GSM Association - which has been working with the Femto Forum since 2008 to develop femto solutions for 3G and 4G - says integration isn't a major issue.
Select all that apply
The upshot is that cellcos are going to need as many of these techniques as possible, and as budgets and assets allow, to cope with the vast amount of data headed their way in the next few years. The good news, says Kaul of ABI, is that various offload options can easily co-exist because each address different aspects of the same basic problem.
"Wi-Fi is effective in covering limited areas containing many users, such as transport stations and sports venues. A femtocell, in contrast, is a good solution for targeting small numbers of heavy data users," Kaul says. "Mobile CDNs attack the problem of frequently-used content, for example a video that has 'gone viral', by caching the file locally rather than loading it onto the network for each download request."
Hartley of Ovum adds that LTE itself will bring extra benefits besides raw capacity to help cellcos manage their data traffic better to ease the burden. "
As you move to LTE, your data traffic efficiency gets better and better, and you'll have better traffic shaping and management tools, content mediation solutions that streamline content so it's purposed for the device, and policy control systems," he says. "You've also got operators moving away from all you can eat, so you can create tiered segments so that the traffic load is less relevant because who cares as long as they're paying for it?"
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