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15 February 2012

Small cells and Wi-Fi join forces to dam the flood of mobile data

Significance: Some cellcos have managed to reduce the rate of growth in mobile data traffic using techniques like offload, but they will soon face a second tidal wave driven by the rise in cloud services, as highlighted in Cisco’s latest Visual Network Index. To deal with that, current tactics will be inadequate in many markets, and cellcos will have to move to the new generation of solutions for carrying multimedia over wireless connections. Central to these will be multimode small cells, supporting LTE, 3G and Wi-Fi, and these need to be integrated right into the heart of the carrier’s core network. As chip vendors race to deliver the multimode small cell, Alcatel-Lucent continues to disrupt the norms of cellular network design by embracing Wi-Fi within its lightRadio platform.

Just as the iPhone shouldered most of the blame for overloading ill-prepared 3G networks with data, so the iPad is set to be the scapegoat for the deluge will may overtake 4G systems. Cisco’s latest Visual Networking Index (VNI) focuses on the next big shift in mobile behavior, to streaming content from the cloud, accelerated by large-screen devices like tablets. This will quickly start to cancel out operators’ recent efforts to control the rise in data traffic over 3G by adopting methods such as offload (to Wi-Fi and femtocells), video optimization, efficiency boosters like active antennas, and other tactics. Such techniques have helped some carriers to slow the rate of the mobile data surge ‘ AT&T and Vodafone have both recently pointed to annual traffic increases of 40% and 20% respectively, rather than the previous 100% (though starting from a higher base of course).

However, this is likely to be a temporary respite, and achieved at considerable expense. Even if AT&T’s previous estimates were on the bullish side to convince regulators that it needed more spectrum in the shape of the T-Mobile buy, the company has been a cheerleader for investing in Wi-Fi for offload, and according to Tim Farrar of TMF Associates, it now offloads about 30% of its total wireless traffic, up from 20% at the end of 2010.

But once the potential of enhancements to 3G macrocells, and offload to WLans, are almost exhausted, the operators will more urgently turn to the next wave of solutions, which revolve around small cells and heterogeneous networks (HetNet). In the run-up to Mobile World Congress, vendors are already vying to help save cellcos from drowning in the data deluge, and while last year was heavily focused on offload, with some nods to 4G changes like HetNet and Cloud RAN, the 2012 show will move the next generation RAN norms to center stage. There will be two key themes in the access network, which cellcos hope will bridge the capacity and efficiency gaps until LTE-Advanced moves things on another step. One will be the next step on from Wi-Fi offload ‘ integration of WLans closely into the operator’s core infrastructure. The other will be the next wave of small cells, as miniature, low power base stations step off the slide decks and into commercial product lines.

All this will hope to build a dyke against the oncoming flood of mobile cloud traffic, as highlighted by the Cisco VNI, whose accurate (or even conservative) forecasts over the past few years have made it something of an industry benchmark despite the obvious vested interest of its provider. This year, Cisco – which recently launched its fastest enterprise Wi-Fi access points to date, specifically citing the data load imposed by tablets – said the US market has already hit the tipping point in moving from downloads or sideloads to streamed content. The cloud now accounts for just over 50% of mobile data traffic (cellular and Wi-Fi) in that region, and by the end of 2012, the cloud figure will be 54% on a global basis, rising to 71% in 2016. And across all forms of mobile content, video will account for over 70% by mid-decade, up from 52% last year.

Another key shift is away from wireless PCs, and towards more fully mobile devices. The VNI defines mobile data as traffic to portable gadgets (notebooks, tablets, handsets) over Wi-Fi or cellular. Laptops are the leading source of wireless data traffic now, on over 80%, but by 2016, smartphones will account for 48% of the total, up from 18% now, and tablets will see the most rapid increase in usage, from just 1% at the start of this year, to 10%.

As always, the top tier of users accounts for a disproportionate share of the traffic and network load, but that tier will grow wider as time goes by, as ownership of data hogs like iPads widens, and as carriers curb the behaviour of the very high end users. At the start of 2010, the top 1% of consumers accounted for a huge 52% of traffic, a figure which fell to 24% a year later. Now, the top 20% of mobile bandwidth hogs are growing their consumption almost three times faster than the top 1%, a pattern shift which will influence how operators will plan their tariffs and their charging structures in future.

By 2016, a mighty 10.8 exabytes of data will be sent over mobile networks each month, with the average consumer using 1.2Gbytes. That’s a global figure, so in some markets the average will be far higher ‘ an estimated 4Gbytes a month in the US, for example, up from 317Mbytes in 2011. And 60% of customers will use more than 1Gbyte of mobile data a month by then, compared to just 0.5% in 2011.

That level of traffic had risen 133% compared to 2010, slightly faster than Cisco had previously predicted. ‘Mobile data traffic will continue to explode. This is a trend we don’t see slowing down,’ said Suraj Setty, VP for service provider marketing. This should spark a bounceback for wireless infrastructure vendors, which have been suffering from carrier spending slowdown in recent quarters. ‘A lot of service providers are increasing their spending on wireless,’ Shetty added in an interview.

Of course, one way to mitigate the additional investment needed in 3G and LTE is to rely more heavily on Wi-Fi ‘ for offload, or as a supplementary carrier network carrying lower upfront cost than licensed technologies. Last year, Wi-Fi carried 38% of total internet data traffic (fixed and mobile), but will overtake wireline connections by 2015 to reach 46.7%. Cellular networks only accounted for 2% of the global total last year, which was still enough to create a strain on 3G systems in some areas of high usage.

Indeed, offloading traffic to Wi-Fi has become a standard tool in operators’ boxes as they struggle against rising data levels. But harnessing their own, or third party, WLans comes with clear trade-offs ‘ unreliable quality of experience in congested spectrum, lack of control of the customer; clumsy sign-in routines when users move to the new network. The industry is moving towards fuller integration of Wi-Fi and 3G/4G, to support unified management of both systems and seamless hand-off, first with initiatives like HotSpot 2.0 and finally by incorporating Wi-Fi into full HetNets. With these issues set to be key themes at Mobile World Congress this month, vendors are racing to set out their stalls.

A year after it stole the MWC thunder with its disruptive lightRadio mobile network architecture, Alcatel-Lucent is welcoming Wi-Fi into the family. ALU is integrating Wi-Fi access points tightly into its lightRadio architecture, allowing users to move seamlessly between the two networks and authenticate with both via the SIM card and the emerging HotSpot 2.0 specifications. There is no need for a special client at the device end and the network can automatically select the best connection based on various criteria such as congestion levels or subscription type, or whether the consumer is moving around. Eventually ALU will include Wi-Fi radios into the lightRadio Cube, the stripped-down base stations at the edge of its innovative topology, but until those hit the markets it will support third party APs as an interim measure.

The lightRadio Wi-Fi solution is based on ALU’s 7750 service edge router, which now gains a Wi-Fi gateway, plus new software for the firm’s policy manager, the 5780 Dynamic Services Controller. The latter will now support teh 3GPP’s ANDSF (automatic network discovery and selection function). ALU will support Wi-Fi access points from partners (to be announced) and, in future, metrocells or femotcells running both 3GPP and WLan technologies. The system will support seamless hand-off and allow operators to keep track of their users by keeping them within carrier WLans, rather than offloading them to ISPs with unpredictable quality of experience.

The 7750 gateway and the upgraded policy manager are both in trials now, and will start shipping in the next couple of months. ALU’s lightRadio architecture for cellular systems is in trials with several carriers, including China Mobile and reportedly Sprint, and deconstructs the classic RAN, relying on virtualized baseband processing to support slimmed-down cell site units consisting of integrated antennas and radios. These base stations, with the new Wi-Fi option, will roll out late this year and into 2013.

Meanwhile, BelAir has been in the vanguard of creating carrier class WLans to handle large scale mobile data offload, and has its eyes on a place in the integrated 4G/Wi-Fi network. It has outlined the enhancements to its GigXone platform, which is designed to evolve towards multi-access networks of small cells. The updated system focuses on rapid deployment and simplified management once networks reach thousands of access points, and also boosts capabilities for handling video. New video over WLan hardware features boost buffering speeds by up to 500% and use dedicated video priority queues and video rate adaptation algorithms.

In keeping with the theme of the month, GigXone also promises tighter integration with existing mobile and fixed access and core networks, and updated anti-interference filters. The system is designed to simplify secure access to Wi-Fi and multi-access metrozones for end users, particularly with auto-authentication, and also help operators provide managed services to small and medium businesses.

Meanwhile, release 12 of the BelAirOS operating system claims to increase individual AP performance by 15%-20% to improve capacity. CEO Bernard Herscovich said: ‘Service providers can offer ‘Gig Zone’ indoor and outdoor services with improved network capacity for millions of subscribers, addressing video and other rich applications that consume 60%-70% of capacity, without the need to retrofit core or access networks to work with systems built for indoor enterprise Wi-Fi access.’

As well as vendors coming from the access network, gateway specialists are riding the carrier WLan wave. Stoke’s multi-access gateway heritage is coming into its own, and the firm has unveiled a new iteration of its Wi-Fi Exchange, which allows cellcos to continue to keep contact with their subscribers even while they are on a WLan.

The Exchange comes with Clientless Interworking, which addresses the issue of inconvenient sign-in, or unpredictable user experience, when a consumer moves to Wi-Fi. It eliminates the need for software or hardware changes at the device end in order to access the WLan and supports a secure and fully featured user experience even when offloaded. And the carrier can gain visibility over Wi-Fi subscriber traffic in order to allocate capacity and optimize performance, while remaining connected with their customers throughout. Clientless Interworking harnesses the functionality defined by the 3GPP Wireless Lan Interworking specifications.

‘With the expanding availability of Wi-Fi, mobile users are increasingly choosing Wi-Fi over cellular, distancing them from the mobile operator. Operators’ current strategies leveraging unmanaged Wi-Fi offload are reinforcing this effect, which represents a major threat to the business model,’ said Stoke’s CTO, Dave Williams, in a statement. ‘Our offering helps to solve these challenges.’

The gateway and packet core solutions which are currently being evolved to bring Wi-Fi into the heart of the network will be developed further over the coming years to support small cells of all flavors in a unified way ‘ 3G, 4G, Wi-Fi and multimode, in different spectrum bands, all leading towards the true HetNets, which will usually create a layer of mixed small cells, in a separate band from the macro network, and passing traffic constantly between the two to maximize capacity and bring signals close to the user wherever practical.

Approaches like lightRadio and Cloud RAN, which centralize the baseband processing, are not confined to small cells, but do address some of the challenges of unifying so many different resources to create a common pool of capacity. And long before HetNet is a reality, 3G and 4G cells will be shrinking to the size of the carrier Wi-Fi access points, applying some of the techniques pioneered in the residential femtocell ‘ self-provisioning, interference management, power efficiency and low cost SoC platforms ‘ to the public access base station or metrocell. This, of course, is seen as the most powerful weapon in the carrier’s fight against being swamped by mobile traffic, and a recent Rethink Research survey of operators worldwide found that LTE-Advanced’s inherent support for small cell architectures was the number one reason why carriers aimed to adopt the new standard as soon as possible ‘ and had driven them to bring forward their deployment plans by an average of 10 months compared to a year ago.

As Reed Hundt, former FCC chairman, put it in a recent interview: ‘God only made a certain amount of spectrum. To go beyond that you have to have a different architectural solution, and that’s where microcells come in.’ Reflecting how a technology that was, until recently, confined to the home has moved swiftly into the main carrier networks, the Femto Forum is changing its name to the Small Cell Forum in time for the MWC show.

The industry body’s remit will now embrace standards, policy and market awareness for all kinds of small base stations ‘ for residential, enterprise, rural and metrozone use, and including indoor and outdoor, and public or private access deployments. This represents a total market of about 4.3m units this year, and while 90% of those will still be residential in 2012, the Forum believes two-thirds of revenue will come from public access products. While this is unlikely to silence the semantic arguments over the differences between picocells, metrocells, femtocells and so on, at least the adoption of the umbrella name reflects the common architectures on which many of those variants will be built.

The Forum and its key members have spent the past few years pushing a residential technology into a broader arena, and arguing that many techniques previously considered applicable only to consumer grade gear were actually suited to carrier class infrastructure. System-on-chip platforms with low power and low cost will be as essential to public access base stations as to femtocells, as will qualities like self-provisioning and no-touch management. So, while specialist femto companies like Picochip have pushed into the metrocell area, traditional network chip suppliers like Texas Instruments have borrowed many femtocell techniques for their latest ‘base station on chip’ designs.

Reflecting that trend, the renamed Forum will ‘serve to develop consensus on common approaches, standards and agreed best practice for all small cells that operate in licensed spectrum, are operator-managed and feature edge-based intelligence’, said the organization’s statement. It will also continue to make submissions to industry standards bodies like the 3GPP, and will work with bodies governing related technologies which also address the capacity crunch, and are likely to work alongside metrocells as often as compete with them. These include Wi-Fi, Cloud RAN, Distributed Antenna System (DAS) and HetNet. The key role of the Forum is to ‘tackle the practical challenges facing deployment’ such as interaction with other cells and technologies, backhaul or site planning.

‘Femtocell technology was originally designed for the home but has since extended into enterprise picocells, urban metrocells and modern microcells for all manner of locations,’ said Forum chairman Simon Saunders. ‘The core technologies developed by members of the Femto Forum – including systems on a chip, provisioning systems, standardized gateways, and other related innovations – lower the cost of licensed band solutions and facilitate easy deployments for all small cell products. Surveys show operators regard small cells as playing a more important role than macrocells in future mobile networks.’

While ABI Research came up with the figure of 4.3m small cells in 2012, another research firm, NPD In-Stat, is looking ahead and believes there will be 160.3m active small cells by 2015, and the retail value of shipments of these products will have reached $14bn. In-Stat sees five SoC architectures vying for the market ‘ MIPS, as used in residential devices powered by Broadcom or Cavium; existing mobile processors adapted to femtocells, like Qualcomm’s Femtocell Station Modem, which is based on Snapdragon, or Intel’s Atom-based Edge Cloud; SoCs combining ARM processors with DSPs, from suppliers like Picochip/Mindspeed and Texas Instruments. In addition to these current options, x86 could take a bigger role in picocells, with Intel planning a network processor for base stations in 2013; and Power Architecture may enter the space as computational power requirements rise, with Freescale the chief proponent (although it also has ARM products).

For the early years of small cells, one name has been both the market leader and the chief advocate of the approach ‘ the UK’s Picochip, which pioneered the femtocell SoC architecture (and even coined the ‘femtocell’ name) and was recently acquired by Mindspeed, the innovative chip firm aiming to take on Freescale and TI in the LTE base station. Just a week after the deal was finalized, the companies announced their first joint product. The dual-mode LTE/3G system-on-chip for small cells showcases how they hope to address the rising tide of carrier interest in tiny base stations, as a way to increase capacity and coverage in their new networks. They aim to stay at the leading edge of this trend by combining their relative strengths ‘ Picochip’s lead in femtocell SoCs, and Mindspeed’s innovations in LTE with its Transcede integrated architecture.

Although most of the base station chip suppliers are describing multimode ‘base stations on a chip’, Mindspeed is confident that its T22xx and T3xx offerings, which are sampling now, will be the first to deploy in the real world. It will be targeting the new products at a substantial base for such a nascent market ‘ between them, the two companies claim over 30 design wins for Transcede and a 70% share of the HSPA small cell space, and Picochip has enabled over 1m 3G units.

The multimode nature of the new Transcede processors are designed to simplify migration and integration between 3G and LTE, while extending Mindspeed’s reach across residential, enterprise and metrozone applications. The Transcede family now includes NodeB and eNodeB SoCs supporting concurrent 3G and LTE processing, with support for both LTE flavors and for HSPA(+), W-CDMA and TD-SCDMA. There is also a roadmap to LTE-Advanced with the same architecture. Combining 3G and 4G reduces cost and time to market. The T22xx series comes in various models targeting residential, small office/home office and small enterprise applications, while the T33xx options are for enterprise, metro and picocell segments.

“We are moving quickly to combine Mindspeed’s and Picochip’s expertise and portfolios into an offering that is uniquely positioned to help carriers address the challenge of relentlessly growing data demand,’ said Mindspeed CEO Raouf Halim in a statement. ‘Our new dual-mode solutions will enable operators to support both 3G and LTE in a single unit, dramatically improving their business case by delivering twice the benefit at half the traditional per-node opex and capex costs.’

Joe Madden, principal analyst at Mobile Experts, was quote in the statement saying: ‘We expect that shipments of semiconductors for femtocells and picocells will grow tenfold by 2017 … and dual-mode functionality will be essential for the best use of limited spectrum. Mindspeed leads the market in LTE design engagements with its Transcede family, and the addition of Picochip’s 3G technology to this platform creates an extremely attractive proposition for OEMs developing multimode small cells.’

Those multimode cells are likely to be in high demand in the near future, and long before most carriers are even planning LTE-Advanced. To refer back to the Cisco estimates, the firm is predicting compound annual growth in mobile data traffic of 78% between 2011 and 2016 on a global basis, with the Middle East and Africa enjoying the highest rate during that period, at 104%. The US will come in at 74% CAGR and will account for over 18% of the world total for data consumption in 2016, but Asia-Pacific will top that ranking on 40%, followed by western Europe on 22.5%. With traffic volumes of that scale in view worldwide, the need for modern but affordable architectures will soon become critical.