Femtocells Make a Truce with Wi-Fi for Data Offload

(Jul 6 2011) 3G , LTE , Wi-Fi

1. By Caroline Gabriel, Research Director, Rethink Technology Research

   Femtocells may have entered the consumer mainstream on the back of improved indoor coverage, but for carriers, one of their real attractions is the chance to offload data from overstretched 3G networks. There has been something of a war between the femtocell suppliers and those pushing Wi-Fi offload, but at last week’s Femtocells World Summit in London, it was notable that the femto vs. WLAN dispute had quieted down. This is because the operators themselves are eager to use any spectrum and technology they can get their hands on to cope with the rise in data traffic in urban areas, and so the emphasis has shifted to pooling both resources.

   Doug Pulley, CTO of femtocell silicon leader Picochip, stressed the point that unlicensed spectrum--and therefore its key technology, Wi-Fi--will not drop out of the cellco equation just because LTE comes along. Pulley was keen to see new air interface options, notably LTE for the license exempt bands. WiMAX was the last standard to promote a vision of spanning licensed and open frequencies, but its 5 GHz profile gained little support as its agenda shifted toward 2.5 GHz and mobile broadband. It could still be revived as an unlicensed option for vertical applications like public safety but in the short term, Wi-Fi is the dominant technology.

   The femto community knows it needs to accommodate this, indoors and in public access, as most operators will look to tap into all available bands, and femtocells will need to support that strategy. Picochip is showing the way via a joint development with InterDigital, an initiative that has created a dual-radio gateway in which cellular and Wi-Fi run concurrently, to offer a "super-connection" across licensed and unlicensed frequencies.

   The converged gateway architecture puts a carrier Wi-Fi access point and a 3G femtocell in the same unit, with both radios running on a Picochip integrated circuit. InterDigital has contributed radio resource management and policy software to allow both connections to run simultaneously.

   The companies’ statement said: "A smartphone can receive data over both cellular and Wi-Fi networks simultaneously, and the converged gateway can aggregate the two connections to improve quality of service or segregate different applications over different radios."

   In the former scenario, two weak channels could be combined to improve data rates and reliability. In the latter case, a user might watch streamed video using Wi-Fi’s high bandwidth while keeping 3G, with its superior security and billing capabilities, for mobile shopping. There is also the opportunity to hand over from Wi-Fi in the living room to the femtocell in the homezone to the macrocell outdoors as the consumer moves about.

   For carriers, the combined platform could be attractive, preserving their dedicated and controlled channel to their customers--important for delivering secure or prioritized services, messages to clients, plus voice and SMS coverage--while harnessing the greater bandwidth of 2.4 GHz or 5 GHz for mass Internet traffic. Such approaches could become increasingly important as cellcos get more serious about tiered tariffs that offer different QoS levels and prioritize certain customers or types of traffic.

   The femtocell is increasingly being combined with other devices rather than acting as a stand-alone unit, finding its way into the home router or gateway alongside Wi-Fi and Ethernet, to support an integrated residential access system, or more recently into the set-top box, as TV providers aim to move into mobility and the quad play. This has been seen most recently in France, where Iliad recently acquired the fourth license for its Free Mobile unit. It has already promised disruptively low pricing for voice and data services, and now it plans to tempt consumers further with free femtocells, when it goes live early next year.

   The operator is expected to integrate a femtocell--a tiny indoor base station that creates a dedicated cell, improving coverage and capacity in the home--into its existing Freebox Revolution set-top box. This would be a step toward a quad play offering and would challenge second cellco SFR, which has already included a femtocell into its Neufbox Evolution IPTV set-top box. This can support five 3G handsets in the home but is paid-for, with an upfront cost of €99.

   As well as luring users, Free Mobile could be able to achieve its 3G coverage mandates more cost effectively than with an outdoor network alone. It plans to spend about €3 billion on its 3G buildout and also has an ongoing MVNO deal with Orange, which will end in 2018. Such a strategy indicates why femtocells continue to be disruptive in their effect on how new networks can be built out (more quickly and cheaply) and on the services that can be launched to tempt customers. When they bring new entrants, such as TV providers and even MVNOs, the chance to deliver differentiated and branded services, they will not just support conventional cellcos’ efficiency drives, but help shake up the competitive landscape too.

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