Small cells what s the big idea?

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Issue date 15 February 2012

Small cells – what’s the

big idea?

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Report title: Small cells – what’s the big idea? Issue date: 15 February 2012

Version: Published

The Small Cell Forum, formerly known as the Femto Forum, supports

the wide-scale adoption of small cells.

Small cells are low-power wireless access points that operate in licensed

spectrum, are operator-managed and feature edge-based intelligence. They

provide improved cellular coverage, capacity and applications for homes and

enterprises as well as metropolitan and rural public spaces. They include

technologies variously described as femtocells, picocells, microcells and

metrocells.

The Small Cell Forum is a not-for-profit, international membership

organisation, with membership open to providers of small cell technology and

to operators with spectrum licences for providing mobile services.

The Forum has 137 members including 63 operators representing more than

1.71 billion mobile subscribers – 33 per cent of the global total – as well as

telecoms hardware and software vendors, content providers and innovative

start-ups.

The Forum has three main aims:

• To promote adoption of small cells by making available information to

the industry and the general public;

• To promote the rapid creation of appropriate open standards and

interoperability for small cells;

• To encourage the development of an active ecosystem of small cell

providers to deliver ongoing innovation of commercially and

technically efficient solutions.

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

setting body, but works with standards organisations and regulators worldwide

to provide an aggregated view of the small cell market.

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

be included on our mailing list, please contact:

Email info@smallcellforum.org

Post Small Cell Forum, PO Box 23, GL11 5WA UK

Member Services Lynne Price-Walker lynne@smallcellforum.org

For a full list of members and further information visit our website

www.smallcellforum.org

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

1.1 The ever increasing thirst for wireless data ... 1

1.2 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 ... 5

4.3 Closed vs Hybrid vs Open Access ... 5

4.4 Self-Organising Networks ... 6

5.

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 ... 12

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Version: 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 mobile

networks ... 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 grow

rapidly (Source: Rethink Technology Research) ... 4

Figure 7-1

The Small Cell Forum's scope of work includes small cells themselevs

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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 become primarily data. UK operator Hutchison 3 reported [1] in November 2011 that over 97% of its traffic was data. There are over 100 networks [2] now offering 21Mbit/s and a further 50 delivering up to 42Mbit/s over 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 vendors has 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 the volume 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 customer experience for speed and consistent coverage which exceeds today’s levels and yet continues to be economically 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 capacity and 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 wireless communication at a location doubles every two-and-a–half years.

An analysis of this capacity growth reveals that the vast majority was achieved by spectrum re-use through the 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

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Table 1-1 Technique versus Capacity Gain

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

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 Summit 2011 and strongly argued for early availability of LTE public femtocells. Vodafone Group has been trialing small cells in public outdoor areas. Verizon and Sprint have both stated their intention to adopt small cell architecture5. Telefónica, China Mobile and others have also publicly expressed their intentions to take this approach.

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

Furthermore, operators rating the business impact of LTE-Advanced features rated small cells to be by far the 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 there were more 3G femtocells in operator networks globally than 3G macrocells7. Many more such milestones are expected over the coming years.

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

For example, according to an independent study by Heavy Reading/ Wireless 20/20, the targeted use of small cells in an environment like London to alleviate capacity bottlenecks can increase operator Free Cash Flow 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 no formal 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 the whole range of licenced spectrum mobile technologies, such as those standardized by 3GPP, 3GPP2 and the WiMAX 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 mobile macrocell 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 units

intended 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 consumption and ease of deployment.

Picocell: Typically used to describe low power compact basestations, used in enterprise or public indoor

areas, the term is sometimes used to encompass outdoor small cells as well. Some care is required in selecting the number and location of these cells for indoor use, although the self-optimising features of newer 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 for

both indoor and outdoor users where macro coverage is insufficient. Occasionally installed indoors to provide 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 metropolitan

areas. Such devices are typically installed on building walls or street furniture (e.g. lampposts and CCTV poles). This category can include technologies such as femtocells, picocells and microcells where they meet these deployment criteria.

HetNet (Heterogeneous Network): A network where a mixture of macrocells, small cells and in some

cases Wi-Fi access points, are employed together to provide coverage with handoff capabilities between them.

Over recent years, the application of the term femtocell has evolved considerably. The early femtocell designs supported up to 4 simultaneous active users and were targeted at residential use. The focus on low hardware 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 for use in large enterprise or public areas. These old-style picocells shared much of the same software and operational systems with their larger cousins, requiring the same level of specialist configuration and planning support.

Over time, femtocell technology has evolved to deliver longer range and higher capacity designs while retaining 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 the needs of small to large enterprises, public spaces and even rural hotspots, while being part of a single coordinated 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 small cells 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 its large installed base, low cost, operator independence and familiarity to consumers and enterprises, thereby making it a valuable component of many operators’ mobile data strategies. Similarly, licensed small cells provide support for all 3G handsets, operator managed quality of service, seamless continuity with the macro networks, ease of configuration and improved security and battery life. Advanced implementations of Wi-Fi can also provide some of these features such as managed QoS and seamless continuity.

Given each technology’s strengths, it becomes clear that Wi-Fi and small cells together complete the toolset that operators need to handle the significant capacity challenge. The result of this has been the increased development of small cell access points that combine both licensed and unlicensed technologies, in order to benefit from the technical advantages of each technology while also employing all available spectrum in the face 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 Access Network) 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 in traditional 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, low

power compact basestation connected through broadband internet. These units typically support four to eight concurrent active users.

Being aimed at high volume, mass market applications cost effectiveness is an important factor. This has been 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 external planning and configuration processes typically required of larger basestations.

Enterprise: These are larger units physically, with higher RF power, longer range and higher traffic

capacity. A range of 8 to 32 concurrent users per device is common, with larger capacity being achieved across a campus or large building by deploying multiple units. Appropriate deployment guidelines allow enterprise IT personnel to successfully plan and deploy these devices, although operator personnel may be involved in the larger deployments. Backhaul may be shared with existing enterprise internet connectivity or use a dedicated connection.

Metro and public space: These have two distinct applications for Urban and Rural environments. Urban

models are designed for high traffic areas, these are engineered into robust cabinets suitable for deployment 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 short range.

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Rural applications: Rural models are designed to meet the need to serve localized hotspots in remote

areas, such as hamlets and small villages, which would otherwise be served from a distant cell tower, or which might not otherwise be economical to serve at all. Rather than using a repeater, a small cell adds capacity and frees up the more expensive resource from the serving macrocell tower. It also allow deployment 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 in

deploying solutions which fit the needs of local environments and changing patterns of mobile usage (Figure 2-2).

4. Technical considerations

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

Interference management

As the number of cells increase in a mobile network, there are more cell borders, leading to greater potential for interference. More automated selection of codes and frequencies is required, with power levels carefully set to balance interference and coverage.

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

Mobility management

With the increased number of cells, fewer end-users are served by each one. Statistical multiplexing becomes less effective, and measures to transfer users across to nearby cells or more actively constrain capacity between users must be taken.

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

There is more neighbour management, with neighbour lists and other data to be negotiated and managed across 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 today’s cellsites is driving 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 attractive option in urban areas. Without the overheads required to share capacity across many moving and different end user devices, a cluster of small cells can share point-to-multipoint wireless backhaul using out-of-band spectrum 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 vary depending on the local constraints.

With more backhaul links, there are also more hubs and aggregation points. Careful planning and performance management is required to avoid creating bottlenecks where capacity is restricted by insufficient 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 to the owner and a nominated list of mobile numbers held in a white-list. This avoids potential abuse by uninvited or unknown users in the area, who may unwittingly use the full capacity of the femtocell and prevent access from the owner. A more sophisticated hybrid option gives priority access to the whitelist, but still 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 broadband consumed. Restricting access avoids concerns that the femtocell owner would have to pay for extra wireline capacity that other, unknown users benefit from. A more sophisticated option used where both fixed and mobile services are provided by the same network operator zero-rates the broadband traffic from the femtocell so that no charges are incurred.

Lastly, there may be concerns where a 3rd party broadband wireline service is used to connect the

femtocell. The end-to-end quality of service cannot be directly managed. If this affects those users unaware that they are being handled by a nearby residential femtocell, the network operator may not have the technical ability to block it.

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

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

Lastly, a hybrid access mode combines the benefits of both options. Any subscriber may gain access, but priority 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 tune the system for maximum performance. Although various software tools are used to assist, manual

intervention is often required to deal with specific circumstances. The introduction of HetNets (Heterogeous Networks) will increase the number and type of cells, with the associated increase in interdependent parameters and interworking. Self-Organising Network (SON) technology, already proven by the femtocell industry, provides a major step towards solving these issues. It promises to radically reduce the need for low level reconfiguration. Instead, the network will continually monitor its own performance, the traffic type and source, adapting itself automatically to achieve optimal performance.

Network planners will still be required of course. Expertise continues to be needed to determine where and when 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 first and largest commercial instance of SON, helping to develop and prove the concepts in the wider netork. In order to achieve low operational costs, the ability for large numbers of consumers to self-install the equipment has been key. This feature is equally applicable to the wider small cell deployments in public areas, enterprise and rural environments.

With such close interaction required between the different layers of a Heterogeneous Network, it is important that open standard interfaces are implemented. These allow different vendors products to be used 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 but one. These different approaches are not mutually exclusive, and it is likely that many network operators will adopt a mix of these solutions, but small cells have become a well-recognised essential component of future mobile networks.

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

Adaptive antennas, MIMO (Multiple-Input Multiple-Output), beam forming and related techniques can provide 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 more difficult. In some countries with larger numbers of site sharing networks, the weight-bearing load of the cell tower has become an issue too.

Many industry analysts believe that the forecast increase in data traffic demand can’t be met by an

evolutionary technology approach using macrocells alone. Research9 has re-inforced that the business case for 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 Cloud RAN 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 fibre links to the data centre. This matches the physical appearance of multiple small cells, and so can also scale to 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 processing capacity 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 which may not be cost-effective or feasible in many territories.

Distributed Antenna Systems: One or more networks may share active or passive antennas spread around a campus, shopping mall or large building. A central machine room hosts large basestations from mobile network 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 limit the amount of frequency reuse. Separate antennas can be connected to different areas of the buildings or campus, but it can be costly to segment and separate smaller parts of buildings. The longer fibre runs may require 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 which are 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 to launch 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 by a small number of active users. Smaller villages and hamlets may not receive high 3G mobile broadband speeds, particularly indoors. The capacity of the serving macrocell is disproportionately consumed when trying to satisfy these needs.

In order to address this problem, Vodafone UK has trialled the installation of femtocells in these villages close to the point of use. Unlike large cell towers, these devices can be unobtrusively installed in public telephone 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 range of 100 metres.

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

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

The incremental cost of the rural femtocell deployment was remarkably low. Vodafone already had the femtocell 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 hardware cost 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 to be in a more robust enclosure because it will be placed in unsupervised areas. Dedicated wireline broadband was 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 femtocell where 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 improved coverage and capacity. Softbank, a pioneering network provider of both wireless and wireline services, has sought 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 longer range 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 backhaul method had to be found. Satellite broadband was used to connect these remote small cells, giving a further benefit 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 solving their customers problems and opening up service to parts of the country previously not served. The cost effective 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 widely dispersed population makes it difficult to provide excellent indoor coverage everywhere using only macrocells. Demand for better service combined with widespread wireline broadband internet availability provide 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 worldwide network 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. Sprint encouraged the development of the 3G CDMA femtocell standard which was released by 3GPP2 in March 2010.11 In August 2010, it launched a 3G standard compliant femtocell using EV-DO with increased voice and 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 already more than 500,000 units in use today throughout Sprint’s customer base and this is expected to double to 1 million 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 mobile devices 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 is connected through “dark fibre” cable. However, the high cost of fibre connections and issues with signal deterioration meant this approach was not ideal. For smaller buildings, the large numbers of standalone RF repeaters used were becoming more difficult to manage. A new concept was needed to deliver higher levels of 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. Voice traffic 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 were connected using the widely available 100Mbit/s wireline broadband service. The network handover algorithms were tuned to prioritise voice traffic onto the macrocell network, and data sessions to the femtocells.

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 mobile experience to 1 Billion users via femto technology”. Clearly, this wouldn’t be achieved by installing

residential femtocells alone – there are many more mobile phone users without the residential wireline broadband service required to support them. Instead, the Forum sought to promote the wider use of femtocell technology for public access. Both 3G and 4G/LTE mobile technologies will require substantially more small cells to be deployed, and the expertise gained through femtocell development has a large contribution to make.

Acknowledging that the scope of the Forum’s activities already embraced the wider range of small cell applications, 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 spectrum

2. is carrier managed rather than completely autonomous

The Forum focuses on the use of edge-based intelligence and processing, albeit centrally managed, rather than approaches which centralise processing. Key aspects of femtocell technology have now been adopted into many different types of small cell, not only those called femtocells. The Forum’s work in establishing the 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 incompatible systems, interfaces and architectures. The Small Cell Forum quickly established a common framework for the key components, interfaces and capabilities within the femtocell architecture. Members jointly supported standardization 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 able to test and resolve interworking between their products. In particular, the Iu-h interface has been shown to allow new femtocell access point entrants to connect to femtocell gateways. This opens up opportunities for many new femtocell vendors to enter the market, introducing innovation, diversity and a healthy element of competitive 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 Forum’s TR.069 management protocol for remote management and configuration or IPsec for secure encryption. The Small Cell Forum worked with

Broadband Forum15 to extend this protocol to include a specific small cell data model (TR. 196). This approach 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 femtocell architecture, 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 the femtocell industry alone, avoiding the trap of high TCO (Total Cost of Ownership) that proprietary solutions bring.

7.3 Dealing with the difficult issues

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

For example, the topic of interference issues, particularly when operating in closed access mode, was dealt with through extensive technical research. Network operators now accept that small cells can be

incorporated into their networks with manageable impact from interference and greatly enhanced user experience and network capacity.

7.4 Proving the market demand

Extensive consumer research was conducted to assess the level of consumer interest in residential femtocell products, and confirmed a resounding demand for improved performance. A 2010 study involving over 1100 participants identified that where coverage is poor, 44% said they would stay with their current operator if they could have a femtocell, and 35% said they’d consolidate all users in the household to the same operator, 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, where large numbers of small cells have been shown to be significantly more effective than the standard macrocell expansion approach.

7.5 Representing the industry

The Small Cell Forum membership has grown to include 66 operators representing 1.99 Billion subscribers worldwide – 34% of the worlds’ total 16. 8 of the top 10 mobile operator groups now offer commercial femtocell 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 point manufacturers through to component suppliers.

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

7.6 Ongoing activities

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

• The Forum’s integrated small cell/Wi-Fi network initiative is establishing the technical and

commercial 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 operator community 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 residential market. The focus of a very low cost, self-installed four channel unit fit for purpose allowed the industry to innovate and address this particular need.

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

As it has matured, early systems have been made more robust and efficient. It is these same femtocell technical 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 using the inherently cost effective features already developed.

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

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

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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. They find that residential and enterprise models currently dominate small cell shipments with 62% and 30% respectively. ABI Research’s data suggests that by 2016, while indoor small cells will be 94% 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 of

smartphones, tablets and other data devices is reflected by the high levels of data traffic carried on mobile networks today.

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

The small cells used in tomorrow’s networks will use many techniques and capabilities originally pioneered for femtocells. Indeed, femtocell technology isn’t restricted to residential or indoor use and has already been incorporated into small cells of all categories. Scalability, automated configuration, self-optimization and rapid 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. The vision of the Forum is to “Deliver great mobile experience to 1 Billion users via femto technology. Far from considering only the residential use case, the Forum has been evangelising the use of chipsets and clever software 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 the pioneering 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 4Gamericas

http://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_Hyperconnecti vity_WP.html

4 Cooper’s Law: http://www.arraycomm.com/technology/coopers-law

5 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=277

8 Rethink Research: presented at Bath Basestation Conference September 2011

http://www.rethinkresearch.biz/index.asp

9 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=263

12 Fierce Wireless: http://www.fiercewireless.com/story/rumor-mill-sprints-ev-do-femtocells-begin-shipping/2010-08-20

13 Fierce Wireless: http://www.fiercewireless.com/story/sprint-will-deploy-lte-advanced-first-half-2013/2011-10-25

14 Light Reading: SK goes Femto for data offload

http://www.lightreading.com/document.asp?doc_id=208709

15 “World's first femtocell standard published by 3GPP”, Forum press release, 7th_{April 2009}

http://femtoforum.org/fem2/pressreleases.php?id=242

16 Informa Femtocell Market Status Report: October 2011 http://femtoforum.org/fem2/resources.php

17 http://www.ecnmag.com/News/2012/02/Multiple-Chip-Architectures-Pursue-the-$14-Billion-Small-Cell-Market

Small cells what s the big idea?

Issue date 15 February 2012