small cells forum 2012-small cells white paper

8/11/2019 Small Cells Forum 2012-Small Cells White Paper

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www.scf.io/ www.smallcellforum.org

RELEASE

DOCUMENT

Small Cells: Whats the Big Idea?

Femtocells are expanding beyond the home

February 2012

030.01.01

SMALL CELL FORUM

One scf.io/


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Report title: Small Cells: Whats the Big Idea?

Issue date: 15 February 2012Version: 030.01.01

Small Cell Forum supports the wide-scale adoption of small cells. Its mission is

to accelerate small cell adoption to change the shape of mobile networks and

maximise the potential of the mobile internet.

Small cells is an umbrella term for low-powered radio access nodes that operate inlicensed and unlicensed spectrum and typically have a range of 10 metres to several

hundred metres. These contrast with a typical mobile macrocell that might have a rangeof up to several tens of kilometres. The term small cells covers femtocells, picocells,

microcells and metrocells.

Small Cell Forum is a not-for-profit, international organisation, with membership open

to providers of small cell technology and to operators with spectrum licences forproviding mobile services.

At the time of writing, the Small Cell Forum has 141 members including 68 operatorsrepresenting more than 3 billion mobile subscribers 46 per cent of the global total

as well as telecoms hardware and software vendors, content providers and innovativestart-ups.

The Small Cell Forum is technology-agnostic and independent. It is not a standards-

setting body, but works with standards organisations and regulators worldwide toprovide an aggregated view of the small cell market.

This document forms part of the Small Cell Forums Release Onewhich addresses thefull range of applications for small cells: Home, Enterprise, Metro, Rural. The main

theme of Release One is the Home, and includes the complete body of work operatorswill need to know for wide-scale deployment of femtocells intended for home or small

office applications. These applications are based typically indoors and involve locationswhere a single femtocell is usually sufficient. Both 3GPP and 3GPP2 femtocells are

included.

Release One also containsworks clarifying market needs and addressing barriers to

deployment of enterprise, metro and rural small cells.

The Small Cell Forum Release website can be found here www.scf.io.A description and

roadmap for the release programme can be found here www.scf.io/doc/100

If you would like more information about the Small Cell Forum or would like to

be included on our mailing list, please contact:

[email protected]

PostSmall Cell Forum, PO Box 23, GL11 5WA UK

Member ServicesLynne Price-Walker [email protected]

For a full list of members and further information visit our website www.smallcellforum.or


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Report title: Small cells whats the big idea?Issue date: 15 February 2012Version: Published

Contents

1. Why do you need small cells ............................................ 1

1.1 The ever increasing thirst for wireless data ............................ 11.2 The range of technical solutions ........................................... 1

1.3 Network operators recognize this inevitability ......................... 1

2. Small Cell Terminology .................................................... 2

2.1 Licenced and Unlicenced Spectrum ....................................... 3

2.2 Vendors agree on the need for small cells .............................. 4

3. Use Cases for small cells .................................................. 4

4. Technical Considerations ................................................. 5

4.2 Backhaul ........................................................................... 54.3 Closed vs Hybrid vs Open Access .......................................... 5

4.4 Self-Organising Networks .................................................... 6

5. Other Solutions ................................................................ 6

6. Case Studies .................................................................... 7

6.1 Vodafone .......................................................................... 7

6.2 Softbank Japan .................................................................. 8

6.3 Sprint ............................................................................... 8

6.4 SK Telecom ....................................................................... 8

7. Small Cell Forum Activities .............................................. 9

7.1 A common architecture ....................................................... 9

7.2 Re-use of existing standards ................................................ 9

7.3 Dealing with the difficult issues ........................................... 10

7.4 Proving the market demand ................................................ 10

7.5 Representing the industry .................................................. 10

7.6 Ongoing activities .............................................................. 10

7.7 Scaling up to the wider capabilities ...................................... 11

8. Summary ....................................................................... 12References ............................................................................... 13


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Report title: Small cells whats the big idea?Issue date: 15 February 2012Version: Published

Tables

Table 1-1 Technique versus Capacity Gain ....................................................... 1

Figures

Figure 2-1 Small cells of all types form an integral part of modern mobilenetworks ....................................................................................... 3

Figure 2-2 A continuum of applications of small cell technology ........................... 3

Figure 2-3 Operator expenditure on small cell infrastructure is set to growrapidly (Source: Rethink Technology Research) .................................. 4

Figure 7-1 The Small Cell Forum's scope of work includes small cells themselevsas well as their interrelation with adjacent technologies ..................... 11


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Report title: Small cells whats the big idea?Issue date: 15 February 2012Version: Published 1

1. Why do you need small cells?

1.1 The ever increasing thirst for wireless data

Mobile networks in many countries have shifted from being predominantly voice networks to becomeprimarily data. UK operator Hutchison 3 reported [1] in November 2011 that over 97% of its traffic wasdata. There are over 100 networks [2] now offering 21Mbit/s and a further 50 delivering up to 42Mbit/sover 3G, with many operators launching 4G/LTE service every month.

Consumer demand for data services is growing unabated, with penetration of smartphones exceeding 40%in many countries and over 300 million being shipped annually. A large ecosystem of application vendorshas emerged, reliant on always on, high speed, low-latency wireless connectivity.

Supporting these applications, the volume of data is continuing to grow rapidly: Cisco predicts that thevolume of wireless data will exceed that of wired data by 2015 [3]

The question is how this enormous data capacity will be realized, consistent with delivering a customerexperience for speed and consistent coverage which exceeds todays levels and yet continues to beeconomically sustainable for operators.

1.2 The range of technical solutions

A great deal of research has been conducted into almost every imaginable way of increasing the capacityand quality of wireless communications. The primary options have been documented by Martin Cooper4,one of the inventors of the portable mobile phone, who observed that the theoretical capacity of wirelesscommunication at a location doubles every two-and-ahalf years.

An analysis of this capacity growth reveals that the vast majority was achieved by spectrum re-use throughthe rollout of a greater number of cells:

Technique Capacity Gain

Frequency Division 5

Modulation techniques 5

Access to wider range of frequency spectrum 25

Frequency reuse through more cell sites 1600

Table 1-1 Technique versus Capacity Gain

This trend will need to continue to support demand growth in the future. LTE and LTE-Advanced offerattractive data rates of over 100Mbit/s as well as low latency and high spectral efficiency. However, as hasproved true in the past, it is widely accepted that to achieve significantly increased speeds in real worlddeployments, and therefore meet the forecasted growth in demand, then many smaller cell sites will berequired.

1.3 Network operators recognize this inevitability

These arguments have not escaped the operator community which has been quick to endorse small cells.NTT DoCoMo presented a detailed analysis of their LTE network performance at Femtocell World Summit2011 and strongly argued for early availability of LTE public femtocells. Vodafone Group has been trialingsmall cells in public outdoor areas. Verizon and Sprint have both stated their intention to adopt small cellarchitecture5. Telefnica, China Mobile and others have also publicly expressed their intentions to take thisapproach.

A recent operator survey by Rethink Research identified that shipments of small cells will exceed those ofmacro basestations in 2014. Furthermore, it found by the end of 2015, the installed base of small cells willexceed that of traditional BTS6.

Furthermore, operators rating the business impact of LTE-Advanced features rated small cells to be by farthe most important. We are about to witness a major transformation of mobile network topology with a


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significant transition of investment. The first indicator of this was the June 2011 announcement that therewere more 3G femtocells in operator networks globally than 3G macrocells7. Many more such milestonesare expected over the coming years.

The outcome will be better services for customers, with fewer limitations on the quality or quantity of datausage, and better business for operators.

For example, according to an independent study by Heavy Reading/ Wireless 20/20, the targeted use ofsmall cells in an environment like London to alleviate capacity bottlenecks can increase operator Free CashFlow by around 19% compared to the use of macrocells alone.

2. Small cell terminology

A number of different terms have been used across different parts of the industry. Although there is noformal definition of these terms, the following section attempts to clarify and distinguish between them.However, it is important to appreciate that the terms do crossover. Small cell technology is applicable to thewhole range of licenced spectrum mobile technologies, such as those standardized by 3GPP, 3GPP2 and theWiMAX forum.

Small Cell:An umbrella term for low-powered radio access nodes that operate in licensed and unlicensed

spectrum that have a range of 10 meter to several hundred meters. These contrast with a typical mobilemacrocell which might have a range of up to several tens of kilometers. The term covers femtocells,picocells, microcells and metrocells.

Femtocell:A low-power, short range, self-contained basestation. Initially used to describe consumer unitsintended for residential homes, the term has expanded to encompass higher capacity units for enterprise,rural and metropolitan areas. Key attributes include IP backhaul, self-optimisation, low power consumptionand ease of deployment.

Picocell:Typically used to describe low power compact basestations, used in enterprise or public indoorareas, the term is sometimes used to encompass outdoor small cells as well. Some care is required inselecting the number and location of these cells for indoor use, although the self-optimising features ofnewer picocells, borrowed from femtocell technology, minimize the amount of specialist knowledge required.

Microcell:Typically used to describe an outdoor short-range basestation aimed at enhancing coverage forboth indoor and outdoor users where macro coverage is insufficient. Occasionally installed indoors toprovide coverage and capacity in areas above the scope of a picocell.

Metrocell:A recent term used to describe small cell technologies designed for high capacity metropolitanareas. Such devices are typically installed on building walls or street furniture (e.g. lampposts and CCTVpoles). This category can include technologies such as femtocells, picocells and microcells where they meetthese deployment criteria.

HetNet (Heterogeneous Network):A network where a mixture of macrocells, small cells and in somecases Wi-Fi access points, are employed together to provide coverage with handoff capabilities betweenthem.

Over recent years, the application of the term femtocell has evolved considerably. The early femtocelldesigns supported up to 4 simultaneous active users and were targeted at residential use. The focus on lowhardware and operating costs led to sophisticated self-configuration and optimization capabilities.

At the same time, macrocell vendors have produced smaller versions of their outdoor cellsites typically foruse in large enterprise or public areas. These old-style picocells shared much of the same software andoperational systems with their larger cousins, requiring the same level of specialist configuration andplanning support.

Over time, femtocell technology has evolved to deliver longer range and higher capacity designs whileretaining the early benefits of scalability, cost-effectiveness, self-configuration and self-management.Modern small cells (femtocells, picocells and metrocells) incorporating this technology can now address theneeds of small to large enterprises, public spaces and even rural hotspots, while being part of a singlecoordinated operator network.


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Figure 2-1 Small cells of all types form an integral part of modern mobile networks

This evolution has led to an overlap in product functionality provided by femtocells, picocells and metrocells.These technologies have now converged to create a continuum which is encompassed by the term smallcells today.

Figure 2-2 A continuum of applications of small cell technology

2.1

Licenced and unlicenced spectrum

The most prominent unlicensed wireless system is Wi-Fi which provides certain unique features including itslarge installed base, low cost, operator independence and familiarity to consumers and enterprises, therebymaking it a valuable component of many operators mobile data strategies. Similarly, licensed small cellsprovide support for all 3G handsets, operator managed quality of service, seamless continuity with themacro networks, ease of configuration and improved security and battery life. Advanced implementations ofWi-Fi can also provide some of these features such as managed QoS and seamless continuity.

Given each technologys strengths, it becomes clear that Wi-Fi and small cells together complete the toolsetthat operators need to handle the significant capacity challenge. The result of this has been the increaseddevelopment of small cell access points that combine both licensed and unlicensed technologies, in order tobenefit from the technical advantages of each technology while also employing all available spectrum in theface of the significant capacity challenge.


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2.2 Vendors agree on the need for small cells

Operator demand for small cells is reflected by all sectors of the industry. Major RAN (Radio AccessNetwork) vendors actively promote HetNets with a mix of large and small cells. Many have offered end-to-end femtocell solutions for several years, all agreeing on the enormous capacity gains possible through the

use of small cells alone.

Research of operator intentions show that by 2015, investment in small cells will grow to exceed that intraditional macrocell and microcells for both 3G and LTE.

Figure 2-3 Operator expenditure on small cell infrastructure is set to grow rapidly (Source:Rethink Technology Research8)

3. Use cases for small cells

There are several distinct applications for small cells:

Residential:This is the original and well understood femtocell concept. A standalone, self-configuring, lowpower compact basestation connected through broadband internet. These units typically support four toeight concurrent active users.

Being aimed at high volume, mass market applications cost effectiveness is an important factor. This hasbeen achieved through high levels of integration, with SoC (System-on-a-Chip) silicon and a low part count.Further savings have been achieved through intelligent software, which automates many of the externalplanning and configuration processes typically required of larger basestations.

Enterprise:These are larger units physically, with higher RF power, longer range and higher trafficcapacity. A range of 8 to 32 concurrent users per device is common, with larger capacity being achievedacross a campus or large building by deploying multiple units. Appropriate deployment guidelines allowenterprise IT personnel to successfully plan and deploy these devices, although operator personnel may beinvolved in the larger deployments. Backhaul may be shared with existing enterprise internet connectivity oruse a dedicated connection.

Metro and public space:These have two distinct applications for Urban and Rural environments. Urbanmodels are designed for high traffic areas, these are engineered into robust cabinets suitable fordeployment in unsupervised areas. Although capable of higher traffic capacity of between 16 and 64

concurrent users, these may not require significantly higher RF power because they target a relatively shortrange.


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Rural applications:Rural models are designed to meet the need to serve localized hotspots in remoteareas, such as hamlets and small villages, which would otherwise be served from a distant cell tower, orwhich might not otherwise be economical to serve at all. Rather than using a repeater, a small cell addscapacity and frees up the more expensive resource from the serving macrocell tower. It also allowdeployment in places where there is no existing macrocell coverage.

Small cells of several types span these use cases, providing a rich pallet of options for operators indeploying solutions which fit the needs of local environments and changing patterns of mobile usage (Figure2-2).

4. Technical considerations

There are several technical factors to be taken into account when considering planning and deployment ofsmall cells. These include not just the radio and backhaul communication, but also any end-user impact andoperational needs.

Interference managementAs the number of cells increase in a mobile network, there are more cell borders, leading to greaterpotential for interference. More automated selection of codes and frequencies is required, with power levelscarefully set to balance interference and coverage.

Self-organising Networks (SON) capabilities co-ordinate between all cells, large and small, to harmonise theparameters and maximize the performance of the entire network.

Mobility managementWith the increased number of cells, fewer end-users are served by each one. Statistical multiplexingbecomes less effective, and measures to transfer users across to nearby cells or more actively constraincapacity between users must be taken.

There are more handovers, requiring efficient and higher capacity to handle the higher signaling traffic andtransaction rates.

There is more neighbour management, with neighbour lists and other data to be negotiated and managedacross clusters of small cells and their larger cousins.

Open interfaces are essential to optimize performance between multiple vendors.

4.2 Backhaul

The need to be able to deploy small cells quickly and in much greater numbers than todays cellsites isdriving development of a wide range of wired and wireless backhaul solutions.

For some situations, NLoS (Non-Line Of Sight) wireless backhaul operating out of band is an attractiveoption in urban areas. Without the overheads required to share capacity across many moving and differentend user devices, a cluster of small cells can share point-to-multipoint wireless backhaul using out-of-bandspectrum of half that licensed spectrum required by each cell.

In other cases, where fibre is widely available, wired backhaul may be more appropriate. Most networks will

evolve using a mix of both wired and wireless backhaul. The technology mix and backhaul topology will varydepending on the local constraints.

With more backhaul links, there are also more hubs and aggregation points. Careful planning andperformance management is required to avoid creating bottlenecks where capacity is restricted byinsufficient backhaul upstream.

4.3 Closed vs hybrid vs open access

Residential femtocells have commonly been designed with a closed-access model. This restricts their use tothe owner and a nominated list of mobile numbers held in a white-list. This avoids potential abuse byuninvited or unknown users in the area, who may unwittingly use the full capacity of the femtocell andprevent access from the owner. A more sophisticated hybrid option gives priority access to the whitelist, butstill allows open access to anyone for the remaining capacity.


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Another reason for the closed access model relates to concerns about the amount of wireline broadbandconsumed. Restricting access avoids concerns that the femtocell owner would have to pay for extra wirelinecapacity that other, unknown users benefit from. A more sophisticated option used where both fixed andmobile services are provided by the same network operator zero-rates the broadband traffic from thefemtocell so that no charges are incurred.

Lastly, there may be concerns where a 3rd party broadband wireline service is used to connect thefemtocell. The end-to-end quality of service cannot be directly managed. If this affects those users unawarethat they are being handled by a nearby residential femtocell, the network operator may not have thetechnical ability to block it.

One undesirable side effect of closed access is that it creates a small number of situations that can affectservice to non-femtocell users. Interference scenarios where non-femtocell and femtocell users conflict areinfrequent, and have been studied extensively by the Small Cell Forum.

More commonly, in enterprise and public outdoor femtocell deployments, an open access model is usedenabling any subscriber from the host network to use it. The backhaul connection is either provided andmanaged by the network operator or the business enterprise. This removes the concerns about cost orquality of the broadband backhaul and provides service to all customers, prepaid, postpaid and roamingvisitors.

Lastly, a hybrid access mode combines the benefits of both options. Any subscriber may gain access, butpriority is given to those on the whitelist.

4.4 Self-organising networks

Large, specialist teams are commonly employed at network operators to plan, design and continuously tunethe system for maximum performance. Although various software tools are used to assist, manualintervention is often required to deal with specific circumstances. The introduction of HetNets (HeterogeousNetworks) will increase the number and type of cells, with the associated increase in interdependentparameters and interworking. Self-Organising Network (SON) technology, already proven by the femtocellindustry, provides a major step towards solving these issues. It promises to radically reduce the need forlow level reconfiguration. Instead, the network will continually monitor its own performance, the traffic typeand source, adapting itself automatically to achieve optimal performance.

Network planners will still be required of course. Expertise continues to be needed to determine where andwhen to install or move equipment and to manage the high level network quality metrics.

The femtocell industry has developed extensive SON expertise and capability. Femtocells have been the firstand largest commercial instance of SON, helping to develop and prove the concepts in the wider netork. Inorder to achieve low operational costs, the ability for large numbers of consumers to self-install theequipment has been key. This feature is equally applicable to the wider small cell deployments in publicareas, enterprise and rural environments.

With such close interaction required between the different layers of a Heterogeneous Network, it isimportant that open standard interfaces are implemented. These allow different vendors products to beused in different parts of the network, so that the best products can be selected for different tasks.

5. Other solutions

Several options are open to network operators to increase coverage and capacity, of which small cells is butone. These different approaches are not mutually exclusive, and it is likely that many network operators willadopt a mix of these solutions, but small cells have become a well-recognised essential component of futuremobile networks.

Macro network expansion: New techniques continue to appear, evolving the existing installed base with thepotential for increased capacity. Additional spectrum is perhaps the easiest technical option, but can be verycostly. Many operators have initially dealt with capacity demand by populating existing sites with their fullcomplement of 3G carriers. Purchase of additional spectrum, refarming 2G for more efficient 3G use andspectrum sharing are all options.

Adaptive antennas, MIMO (Multiple-Input Multiple-Output), beam forming and related techniques canprovide spatial reuse in addition to frequency reuse, further increasing capacity.


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A practical issue with macrocell expansion is where visible changes to the antenna are being made.Neighbourhood opposition to any additional antenna and stricter planning regulations can make this moredifficult. In some countries with larger numbers of site sharing networks, the weight-bearing load of the celltower has become an issue too.

Many industry analysts believe that the forecast increase in data traffic demand cant be met by an

evolutionary technology approach using macrocells alone. Research9 has re-inforced that the business casefor small cells is much stronger than incremental expansion of macrocell towers alone.

Cloud RAN: Cloud RAN (Radio Access Network) products have been launched by several leading vendors.Unlike small cell solutions, where much of the intelligence is distributed to the edge of the network, a CloudRAN concentrates the processing in one or more large, centralized data centres.

A large number of small radio heads are installed in the field, connected by dedicated high capacity fibrelinks to the data centre. This matches the physical appearance of multiple small cells, and so can also scaleto deliver the high capacity and performance of a small cell network.

Large data centres share the processing load across the whole network, reducing the total processingcapacity required and simplifying maintenance and upgrade for new features and functionality.

However, this approach does require extensive high capacity fibre connections to every radio head whichmay not be cost-effective or feasible in many territories.

Distributed Antenna Systems: One or more networks may share active or passive antennas spread around acampus, shopping mall or large building. A central machine room hosts large basestations from mobilenetwork operators. The cost of the system is then shared between networks.

Additional capacity is added by using additional spectrum. While popular for voice traffic, DAS systems limitthe amount of frequency reuse. Separate antennas can be connected to different areas of the buildings orcampus, but it can be costly to segment and separate smaller parts of buildings. The longer fibre runs mayrequire active repeaters to connect to central machine rooms where the basestations reside.

Specialist RF engineers are usually involved in planning and performance tuning these installations whichare best installed during the construction of the buildings rather than being fitted later.

Small cells may be used in conjunction with DAS systems in some situations.

6. Case studies

6.1 Vodafone

Vodafone Group has been actively adopting femtocell technology from an early stage. They were the first tolaunch commercial femtocell service in Europe and now offer this service in 13 countries worldwide.

In rural and sparsely populated areas, the coverage from a wide area macrocell may be heavily affected bya small number of active users. Smaller villages and hamlets may not receive high 3G mobile broadbandspeeds, particularly indoors. The capacity of the serving macrocell is disproportionately consumed whentrying to satisfy these needs.

In order to address this problem, Vodafone UK has trialled the installation of femtocells in these villagesclose to the point of use. Unlike large cell towers, these devices can be unobtrusively installed in publictelephone boxes, community halls and suchlike. The village of East Garston was selected for the first trial,with femtocells positioned in the local pub, community hall and telephone box. These femtocells had a rangeof 100 metres.

The company has invited communities to propose themselves for the scheme. The support of the localcommunity brings greater benefits for all. Residents will be more aware of the improved service and morelikely to change providers to use it. There are less likely to be complaints or objections to the equipmentinstallation.

Trials like these within large multinational operators are closely watched by others within the group, andsuccessful projects may be replicated elsewhere.

The incremental cost of the rural femtocell deployment was remarkably low. Vodafone already had thefemtocell systems commercially in use, including the femtocell gateway, provisioning and configuration


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systems. Planning and operational staff had already been trained in the use of the equipment. The hardwarecost a fraction of that of a large scale cell tower.

There were a few differences between residential and public access deployment. The equipment itself has tobe in a more robust enclosure because it will be placed in unsupervised areas. Dedicated wireline broadbandwas used to ensure good backhaul connectivity. Open access was enabled rather than being limited to a

whitelist. Some configuration of the macrocell parameters was used to facilitate handover into the femtocellwhere possible.

The success of the scheme to date has allowed Vodafone UK to expand it to a wider range of communities.

6.2 SoftBank Japan

Even densely populated countries such as Japan have rural areas which would benefit from improvedcoverage and capacity. Softbank, a pioneering network provider of both wireless and wireline services, hassought to bring full 3G service to these more remote areas quickly and effectively.

Using specially engineered femtocells designed for outdoor use, which have a higher RF power and longerrange than residential designs, Softbank were able to deploy these to serve isolated villages and localities.

Some of the areas to be covered did not have any existing wireline broadband and another backhaulmethod had to be found. Satellite broadband was used to connect these remote small cells, giving a furtherbenefit that this is immediately available throughout all parts of the country.

Using this approach meant that Softbank could deploy rural femtocells in a matter of days, quickly solvingtheir customers problems and opening up service to parts of the country previously not served. The costeffective nature of the small cells brought commercial viability which more traditional methods had not

6.3 Sprint

The more spread-out nature of suburban housing found in many US towns combined with areas of widelydispersed population makes it difficult to provide excellent indoor coverage everywhere using onlymacrocells. Demand for better service combined with widespread wireline broadband internet availabilityprovide the essential ingredients that make a good commercial business case for residential femtocells.

Sprint, the third largest US cellular network with more than 50 million subscribers, was the first worldwidenetwork operator to launch a nationwide commercial residential femtocell service in August 200810.Branded as Airave, the product was sold through retail stores and dedicated internal portal.

Their use of CDMA technology attracted a different set of vendors than mainstream 3G UMTS. Sprintencouraged the development of the 3G CDMA femtocell standard which was released by 3GPP2 in March2010.11 In August 2010, it launched a 3G standard compliant femtocell using EV-DO with increased voiceand data capacity.12 It further extended its femtocell-based services to a higher capacity unit with multi-device clustering capabilities to support larger coverage areas in November 2011.

The service has been a resounding success with many positive reviews from customers. There are alreadymore than 500,000 units in use today throughout Sprints customer base and this is expected to double to 1million by the first half of201313.

Sprint have also announced plans to deploy LTE small cells during 2012.

6.4 SK Telecom

South Korea has some of the highest usage of the internet, both wired and wireless. Data traffic on mobiledevices is intense, both indoors and out, with no sign of future demand growth subsiding.

The operator had earlier deployed substantial numbers of RF repeaters, where the broadband signal isconnected through dark fibre cable. However, the high cost of fibre connections and issues with signaldeterioration meant this approach was not ideal. For smaller buildings, the large numbers of standalone RFrepeaters used were becoming more difficult to manage. A new concept was needed to deliver higher levelsof wireless data traffic more effectively.

SK Telecom sought to replace these repeaters with large numbers of small cells, offloading their data traffic

where possible, especially when used indoors in public areas and other identified traffic hotspots. Voicetraffic would remain on the macrocell network.


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A small cell design was chosen which combined a 3G femtocell and a Wi-Fi access point. These wereconnected using the widely available 100Mbit/s wireline broadband service. The network handoveralgorithms were tuned to prioritise voice traffic onto the macrocell network, and data sessions to thefemtocells.

The operator planned to install more than 10,000 femtocells before the end of 2011 serving 26 million

customers of which more than 10 million have smartphones14.

7. Small Cell Forum activities

At the beginning of 2010, the Small Cell Forum revised its vision statement to become Deliver great mobileexperience to 1 Billion users via femto technology. Clearly, this wouldnt be achieved by installingresidential femtocells alone there are many more mobile phone users without the residential wirelinebroadband service required to support them. Instead, the Forum sought to promote the wider use offemtocell technology for public access. Both 3G and 4G/LTE mobile technologies will require substantiallymore small cells to be deployed, and the expertise gained through femtocell development has a largecontribution to make.

Acknowledging that the scope of the Forums activities already embraced the wider range of small cellapplications, and seeking to encourage a cohesive and coordinated industry approach, the Forum renamed

itself as the Small Cell Forum in 2012.

The Small Cell Forum focuses on all small cell technology which:

1.

operates in licenced spectrum2.

is carrier managed rather than completely autonomous

The Forum focuses on the use of edge-based intelligence and processing, albeit centrally managed, ratherthan approaches which centralise processing. Key aspects of femtocell technology have now been adoptedinto many different types of small cell, not only those called femtocells. The Forums work in establishingthe small cell industry is summarized below.

7.1 A common architecture

It is all too common for innovation in a rapidly evolving new technology to result in a variety of incompatiblesystems, interfaces and architectures. The Small Cell Forum quickly established a common framework forthe key components, interfaces and capabilities within the femtocell architecture. Members jointly supportedstandardization efforts through 3GPP and 3GPP2 which were incorporated and approved in record time.

This has been further reinforced through several Plugfests hosted by ETSI, where vendors have been ableto test and resolve interworking between their products. In particular, the Iu-h interface has been shown toallow new femtocell access point entrants to connect to femtocell gateways. This opens up opportunities formany new femtocell vendors to enter the market, introducing innovation, diversity and a healthy element ofcompetitive cost control.

7.2 Re-use of existing standards

The Small Cell Forum has sought to identify and adopt existing standards where appropriate solutions

already exist. Examples include the use of the Broadband Forums TR.069 management protocol for remotemanagement and configuration or IPsec for secure encryption. The Small Cell Forum worked withBroadband Forum15 to extend this protocol to include a specific small cell data model (TR. 196). Thisapproach brings many advantages:

Widely adopted standards with mature, cost effective products already available. Reduced risk by using proven, mass market technologies Faster time to market avoiding the need to develop, debug and mature additional technology Lower cost because the implementation of the standard is spread across a wider range of

applications, large enough to bring competitive pressure which keeps costs low Compatibility with existing mobile networks that do not require modifications to handsets or core

network components.

Solution vendors have simply been able to incorporate existing products into their overall femtocellarchitecture, such as TR.069 capable management systems (ACL) and high capacity IPsec security

gateways.


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The longer-term ongoing maintenance of these parts of the solution does not have to be borne by thefemtocell industry alone, avoiding the trap of high TCO (Total Cost of Ownership) that proprietary solutionsbring.

7.3 Dealing with the difficult issues

As the femtocell industry evolved, a wide range of potential blocking issues have been brought up. TheFemto Forum has faced up to each one in turn, producing a range of more than 20 technical and marketpapers addressing individual issues.

For example, the topic of interference issues, particularly when operating in closed access mode, was dealtwith through extensive technical research. Network operators now accept that small cells can beincorporated into their networks with manageable impact from interference and greatly enhanced userexperience and network capacity.

7.4 Proving the market demand

Extensive consumer research was conducted to assess the level of consumer interest in residential femtocellproducts, and confirmed a resounding demand for improved performance. A 2010 study involving over 1100participants identified that where coverage is poor, 44% said they would stay with their current operator ifthey could have a femtocell, and 35% said theyd consolidate all users in the household to the sameoperator, with some 60% of households overall being interested in having a femtocells.

Technical studies have also demonstrated the strong business case, particularly for data offload, wherelarge numbers of small cells have been shown to be significantly more effective than the standard macrocellexpansion approach.

7.5 Representing the industry

The Small Cell Forum membership has grown to include 66 operators representing 1.99 Billion subscribersworldwide 34% of the worlds total 16. 8 of the top 10 mobile operator groups now offer commercialfemtocell services today, with a total of 36 commercial femtocell services live at the time of writing.

Membership also includes 70 vendors, ranging from end-to-end solution integrators, femtocell access pointmanufacturers through to component suppliers.

The Forum can truly claim to represent the interests of the entire small cell industry, speaking for it withone voice and securing partnerships and agreements on their behalf.

7.6 Ongoing activities

The Small Cell Forums scope of work (Figure 4), encompasses the wide range of enabling factors forlicensed spectrum, operator-managed small cells of all varieties including femtocells, picocells, microcellsand metrocells. Additionally, where other systems have a specific small cell interrelation, the Forum worksindividually and collectively with other organisations to make the most of the synergies. For example:

The Forums integrated small cell/Wi-Fi network initiative is establishing the technical andcommercial potential for networks which integrate these two technologies to deliver fine-grained,

smart offload capabilities for all devices in a well-managed fashion. The Forum has LTE and rural small cell groups to focus on the special requirements of these

technology and use-case options The Forum is working on radio and network aspects of enterprise and public access small cells The Forum is continuing to support the evolution of standards The Forum is working to spread best-practice amongst operators as success stories from the

pioneers of small cell deployments work to share their knowledge with the wider operatorcommunity to encourage a flourishing ecosystem


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Figure 7-1 The Small Cell Forum's scope of work includes small cells themselves as well as

their interrelation with adjacent technologies

7.7 Scaling up to the wider capabilities

The extensive work achieved in taking femtocell solutions to market was initially targeted for the residentialmarket. The focus of a very low cost, self-installed four channel unit fit for purpose allowed the industry toinnovate and address this particular need.

With some 30 commercially active deployments worldwide, a total of around 50 operator commitments todeploy, and millions of femtocells in use today, this is a market and technical success. The Small Cell Forumhas helped accelerate the pace of adoption, dealing with common issues, promoting the industry andsupporting its growth.

As it has matured, early systems have been made more robust and efficient. It is these same femtocelltechnical capabilities which are now fit to be scaled up to meet a wider range of applications and use cases:

Extended range can be achieved by fitting a higher power RF front end and larger antenna Higher traffic capacity and faster data speeds can be achieved by using more powerful silicon Outdoor metrocells for unsupervised areas can be engineered with a different form factor Remote rural small cells can be connected using satellite backhaul

However all of these applications can share the same femtocell gateways and management systems usingthe inherently cost effective features already developed.

This expansion into a wider range of applications builds on the success from residential and enterprisefemtocells.

Market forecasts from a range of reputable analysts project rapid growth of all types of small cells:

iDate forecast a cumulative total of 39.4 million units shipped by 2015 Infonetics forecast annual growth rates of more than 100% from 2012 onwards, with more than

5 million units shipped during that year alone Visiongain estimates femtocell revenues will reach $27 Billion by 2016 Instat forecast there will be 160.3 million active small cells, and the retail value of small cell

shipments will reach $14 billion by 201517. Infonetics predict that global femtocells revenues will nearly double and shipments will grow at

nearly 140% in the course of 201218.


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According to ABI Research, 4.3 million small cells (including femtocells, picocells and microcells)will be shipped in 2012, rising to 36.8 million shipments in 2016, valued at $20.4 billion. Theyfind that residential and enterprise models currently dominate small cell shipments with 62% and30% respectively. ABI Researchs data suggests that by 2016, while indoor small cells will be94% of total shipments, outdoor small cells will make up 64% of the revenue.

8.

Summary

Rapid forecast growth in mobile broadband data demand is becoming a reality. Strong takeup ofsmartphones, tablets and other data devices is reflected by the high levels of data traffic carried on mobilenetworks today.

The mobile industry has established a consensus that Heterogeneous Networks (HetNets), comprising a mixof small and large cells, will be essential to satisfy the capacity, speed and performance requirements of thefuture.

The small cells used in tomorrows networks will use many techniques and capabilities originally pioneeredfor femtocells. Indeed, femtocell technology isnt restricted to residential or indoor use and has already beenincorporated into small cells of all categories. Scalability, automated configuration, self-optimization andrapid deployment have been taken to new limits by the millions of femtocells in commercial use today.

The Small Cell Forum and its members have contributed significantly to the progress made to date. Thevision of the Forum is to Deliver great mobile experience to 1 Billion users via femto technology. Far fromconsidering only the residential use case, the Forum has been evangelising the use of chipsets and cleversoftware which embody femto technology for a wider range of uses.

Mobile network users worldwide will benefit from higher quality, lower cost and faster service through thepioneering work of the femtocell industry, embodied in the whole range of small cell types.


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References

1 Fierce Wireless http://www.fiercewireless.com/europe/story/3uk-data-traffic-our-network-approaching-100/2011-11-02

2 4Gamericashttp://www.4gamericas.org/UserFiles/file/Global%20Status%20Updates/Global%20Status%20Update%20Nov%202x.pdf

3 Cisco VNI Survey:http://www.cisco.com/en/US/solutions/collateral/ns341/ns525/ns537/ns705/ns827/VNI_Hyperconnectivity_WP.html

4 Coopers Law: http://www.arraycomm.com/technology/coopers-law5 Connected Planet: http://connectedplanetonline.com/3g4g/news/4G-World-Verizon-exploring-small-

cells-for-adding-future-capacity-1025/6 Coping strategies for the mobile data explosion, Rethink Technology Research, 2011.7 3G femtocells now outnumber conventional 3G basestations globally, Femto Forum press release, 21st

June 2011 http://femtoforum.org/fem2/pressreleases.php?id=2778 Rethink Research: presented at Bath Basestation Conference September 2011

http://www.rethinkresearch.biz/index.asp9 Alcatel Lucent Small Cells Business Case: http://www.alcatel-

lucent.com/wps/DocumentStreamerServlet?LMSG_CABINET=Docs_and_Resource_Ctr&LMSG_CONTENT_FILE=Other/May2011_Small_Cells_EN_BusCaseOverview.pdf

10 Fierce Wireless: www.fiercewireless.com/story/sprint-goes-nationwide-airave-femtocell/2008-07-30 11 Femto Forum/3GPP2 Press Release: http://www.femtoforum.org/fem2/pressreleases.php?id=26312 Fierce Wireless: http://www.fiercewireless.com/story/rumor-mill-sprints-ev-do-femtocells-begin-

shipping/2010-08-2013 Fierce Wireless: http://www.fiercewireless.com/story/sprint-will-deploy-lte-advanced-first-half-

2013/2011-10-2514 Light Reading: SK goes Femto for data offload

http://www.lightreading.com/document.asp?doc_id=20870915 World's first femtocell standard published by 3GPP, Forum press release, 7thApril 2009

http://femtoforum.org/fem2/pressreleases.php?id=24216 Informa Femtocell Market Status Report: October 2011 http://femtoforum.org/fem2/resources.php17 http://www.ecnmag.com/News/2012/02/Multiple-Chip-Architectures-Pursue-the-$14-Billion-Small-Cell-

Market

18 http://www.infonetics.com/pr/2011/3Q11-2G-3G-4G-Femtocell-Market-Highlights.asp

small cells forum 2012-small cells white paper

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