Small Cells and 5G Evolution

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DOCUMENT

Small Cells and 5G EvolutionA Topic Brief

June 2015

055.05.1.01

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SMALL CELL FORUM

RELEASE 5.1

VIRTUALIZATION

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Report title: Small cells and 5G evolution: a topic brief Issue date: 09 June 2015 Version: 055.05.1.01

Executive summary

In the absence of any clear definitions or standards, as yet, for ‘5G’, there is considerable hype around the next generation of mobile network technologies. However, whether that proves to be an evolution of 4G or something entirely new, it is clear that operators will need new platforms to address the huge increase in data traffic and device volumes in the 2020s, created by many emerging trends, from 8K mobile video to the billions of sensors that will help to make up the Internet of Things.

This is the right time, then, for operators, vendors, R&D labs and standards bodies to start the discussion – hype-free, and focused on real world requirements – about what they believe 5G should include, building on a couple of years of preliminary work already begun by operators, vendors and industry bodies round the world. R&D cycles are long, and it is important that some guiding principles are established to ensure engineering work, and investment, are geared to commercial realities. And in the meantime, some of the work may also have a nearer term impact, if it is fed into future iterations of LTE.

Among these efforts, the recent NGMN (Next Generation Mobile Network) Alliance’s white paper is an important contribution. It details end-to-end operator requirements for 5G, with the aim of guiding the development of future technology platforms and standards, and sets out some core goals for the new network. This indicates a key role that industry alliances have to play in these early stages of defining 5G - tying broad principles to real operator requirements and use cases.

The Small Cell Forum believes that, like the NGMN Alliance, it has an important role to play in this respect. It shares the broad objectives set out in the NGMN white paper but can complement that work by:

• Defining more specifically how small cells architectures can contribute to achieving objectives like network density and energy efficiency.

• Providing leadership for the ecosystem in how to apply principles, such as the open ecosystem and consistent user experience, specifically to small cells.

One of the areas of agreement about 5G is that it will involve ever-smaller cells, whether to support dense zones of high capacity, or ever-increasing data consumption indoors. That means that the Small Cell Forum has a particularly significant input to make to the early 5G process, since it is the main body defining requirements, use cases and interfaces for this technology.

There are six clear examples of areas where the Forum already has highly relevant activity, and which will be essential to any future dense small cell network architecture – whatever the specifics of the platform for 5G. These are all areas where robust, universal specifications, based on real operator requirements, will be critical for successful deployment, and where 5G will benefit from being built on work which is already ongoing for LTE and even the body of work completed on 3G.

These six areas are:

• An ecosystem based on open standards to ensure multi-vendor interoperability even if specific implementations are diverse

• A heterogeneous and self-organizing architecture to support 5G cost efficiencies and flexibility, and to be adaptable to future technologies or spectrum


• An agile architecture which can provide unity but with the flexibility to address future technologies and use cases — for example evolving to address the virtualization of the small cell layer into physical network functions (PNFs) and virtual network functions (VNFs).

• A modular solution framework that allows for diversity of application, and for competition across the ecosystem.

• A common API (application programming interface) framework to encourage development of new and future services in an interoperable way, as well as practical experience of dealing with the alternative business models for small cells.

• A track record of cooperating with other industry bodies to achieve integration with their platforms, as seen in the work on Wi-Fi integration. Harnessing multiple technologies in a harmonised way is likely to be an important element of 5G.

Issues associated with small cells - such as new levels of cost and power efficiency, self-organization, dynamic capacity allocation and automation - are already visible in 3G and 4G small cells, so the Forum will be able to draw on existing real world work and experiences in order to inform 5G initiatives.


Contents

1. Introduction .....................................................................1 2. Small cells in 5G ...............................................................3 3. Areas of contribution ........................................................5 3.1 An ecosystem based on open standards to ensure multi-

vendor interoperability even if specific implementations are diverse ............................................................................... 5

3.2 A heterogeneous and self-organizing architecture to support 5G approaches to cost and flexibility, and to be adaptable to future technologies or spectrum ............................................ 6

3.3 An agile architecture which can provide unity but with the flexibility to address future technologies and use cases ............ 7

3.4 A modular solution framework which allows for diversity of applications, and for competition across the ecosystem ............ 8

3.5 A common API (application programming interface) framework to encourage development of new and future services in an interoperable way ............................................ 9

4. Conclusion ...................................................................... 11 References ................................................................................ 12

Figures Figure 2-1 Some visions of small cells’ role in 5G ............................................... 4 Figure 3-1 The 3G Small Cell Application Platform Interface structure ................... 9

Report title: Small cells and 5G evolution: a topic brief Issue date: 09 June 2015 Version: 055.05.1.01 1

1. Introduction

Even while 4G remains, in many areas, in the first stages of full commercial deployment, there is intense industry interest surrounding ‘5G’. Some of the 5G talk is hype, and some of the assumptions being made about the architectures look premature. The 3GPP is just in the early stages of its work, for instance (it has initiated a study item on 5G use cases and announced a RAN workshop planned for later this year), and while a few operators claim they will have networks based on ‘pre-5G’ systems running in 2019, the majority will not deploy a new generation until well into the 2020s.

Nonetheless, this is the right time to start thinking about how the fifth generation of mobile networks will look. R&D cycles are long, and it is important that some guiding principles, based on real operator requirements, are established in 2015, to direct the work of the labs and engineers over the coming years and relate it to today’s commercial realities and tomorrow’s commercial expectations.

The pressures on mobile service providers are intense, and some are looking for a radical new approach to network design to support an increase in traffic of perhaps 1,000 times by 2020, together with a proliferation of new devices and applications in areas like the Internet of Things. For many, that new design will evolve on an ongoing basis over the coming years, with developments like ultra-dense networks and virtualization starting to be deployed in LTE evolutions, and then feeding into future 5G standards.

Amid all this commercial and technological change, it is essential that industry initiatives start establishing now what carriers will require from 5G in order to support new and profitable business models in future, so that R&D and standardization efforts are driven by real business needs. Until ITU-R publishes its technical performance requirements for IMT-2020 and official standards bodies, notably 3GPP, start their own work, it can be argued that none of this is really 5G, but undoubtedly the efforts of alliances like NGMN will lay some of the groundwork for the future – and in the nearer term, will also feed into the evolution of LTE-Advanced.

Among these efforts, the recent Next Generation Mobile Network (NGMN) Alliance’s white paper is an important contribution [1]. It details end-to-end operator requirements for 5G, with the aim of guiding the development of future technology platforms and standards. A global team of more than 100 experts contributed to the white paper by developing the consolidated operator requirements. In summary, these include:

• A network with far greater throughput, lower latency and higher connection density

• A high degree of flexibility and scalability by design to cope with a wide range of use cases and business models

• Foundational shifts in cost and energy efficiency • On the end user side, a consistent customer experience achieved across the

time and service footprint • A 5G ecosystem that is truly global, free of fragmentation and open for

innovations.

Other initiatives, such as the European Union’s METIS program, as well as individual companies, are also contributing many ideas and proposals. Similar core goals are shared by many of these efforts, but the NGMN Alliance publication in particular indicates the role that alliances have to play in these early stages of defining 5G, by


tying the broad principles to real operator requirements and use cases. This is the right moment to make that input, before vendors or standards groups have gone too far down the road in defining a particular approach.

The most significant recent example of the need to look ahead to future business cases when defining core standards is the limitation of the original LTE standards adequately to support machine-to-machine communications, or to anticipate the disruption that is embodied by the Internet-of-Things. Nobody can fully predict the future of course, but early-stage, real world consideration of operator plans and requirements is important.

The Small Cell Forum believes that, like the NGMN Alliance, it has an important role to play in this respect. It shares the broad objectives set out in the NGMN Alliance white paper but can complement that work by:

• Defining more specifically how small cells architectures can contribute to achieving objectives like network density and energy efficiency, and potentially contributing the results to the 3GPP’s work on the RAN architecture, which starts in Q315, as it has contributed to 3GPP standards in the past

• Providing leadership for the ecosystem in how to apply principles, such as the open ecosystem and consistent user experience, specifically to small cells.

• Cooperating with other initiatives in which its technologies and experience fit naturally, such as ETSI’s Mobile Edge Cloud project.

Like the NGMN Alliance, the Forum is heavily focused on operator requirements, which have been defined in detail and fed into its range of standard specifications – including the small cell functional application platform interface (FAPI). These requirements also underpin its Release Program, which provides deployment guidelines and technology support in the areas of home, enterprise, urban, rural/remote and virtualization. One of the founding principles of the Forum was to further one of the most fundamental of operator requirements: interoperability and the cost-efficient ecosystem that it produces. Efforts in this area, such as successive plugfests and interoperability testing initiatives, will be vital in 5G too.

While those efforts have been focused on short-term deployment plans and architectures, the Forum can perform a similar role in contributing to next generation network platforms.


2. Small cells in 5G

There are few areas of agreement about 5G. Whether it will require a new air interface – or several; whether it will primarily be driven by ultra-low power IoT technologies or by escalating broadband data usage; how far the network will be fully virtualized and cloud-based – all these are important debates which so far have no clear answer. But there is consensus on some of the challenges 5G must address in order to support commercial success for service providers, including:

• Support for new applications beyond mobile broadband with diverse performance, reliability, security and other requirements

• Support for vast numbers of devices in the IoT • Support for a huge variety of devices and connections, ranging from ultra-low

power to low latency super-broadband • Support for diverse spectrum bands and types with flexible allocation of radio

resources to improve cost efficiency and performance • Support for a wholly new TCO base to support a new generation of ultra-low

cost devices and usage fees, as well as to enable profitability from high broadband usage

• Support for a more open ecosystem, probably including a large element of open source.

Supporting those broad objectives, important generic principles which will be central to 5G are

• Efficiency (under a broad set of utility constraints) • Resiliency • Modularity, scalability, flexibility and manageability • Compatibility with programmable SDN/NFV frameworks • Enablement of easily deployable, open value creation platforms

With those fundamental objectives in mind, one of the few areas of agreement on the architecture to deliver them is that ever-smaller cells will be a critical element, and will enable the use of new, higher frequency spectrum bands. Very dense zones of tiny cells may be designed to deliver large amounts of targeted capacity in an area of high data usage such as a stadium; or to support highly localized M2M device clusters at very low power. They can be switched off automatically at times of low usage to save power, and can deliver new kinds of services which rely on close proximity to the user.

Along with virtualization and expansion into high frequency bands, small cells are among the few assumptions already being agreed about 5G (and these three core elements of the future network are, of course, closely related). Therefore, it will be important to consider past and current challenges with small cells when planning future architectures, so that 5G efforts can build on existing experience and avoid past mistakes. That means that the Small Cell Forum has a particularly significant input to make to the early 5G standardisation process.

The NGMN Alliance paper assumes the use of small cells and “cell densification, with base stations using very different transmit powers and antenna configurations. We note that while cell densification is supported in LTE, the current architecture hasn’t been designed to natively support small cells.” Early ‘pre-5G’ demonstrations have included small cells running in high frequencies (above 24 GHz and going up to millimeter wave bands); in combination with massive MIMO and Cloud-RAN; and in complex HetNets involving many different spectrum bands and air interfaces.


Other 5G initiatives have contributed large amounts of work on ultra-dense networks of small cells, often in high frequency bands. Examples include the METIS project, as well as work by the Fraunhofer Institute in Germany, and by cutting edge operators such as China Mobile and NTT Docomo.

Figure 2-1 Some visions of small cells’ role in 5G

Sources: CMCC (l) [2] and METIS (r) [3]

With small cells set to play such a prominent role, it is important that the main body defining requirements, use cases and interfaces for this technology has an active input into 5G efforts. This is especially true because 5G is unlikely to be a complete technology break with the past. Many believe that operators will continue to use their LTE macro networks for coverage and wide area mobility for many years to come, with ‘5G’ developments entirely focused on a separate layer of dense capacity to support new types of usage, from very high speed broadband to the low power IoT.

The definition of the small cell is broadening to reflect operators’ changing requirements, and a continuum can be seen from the traditional homogeneous femtocell, to futuristic ideas, like Artemis’s pCell (which co-ordinates transmissions amongst an array of small physical cells to create a tiny personal cell of coverage on demand around a user), which may well influence 5G specs – but could also become relevant earlier than that.

Therefore it is important that, however radical the overall 5G approach, it must also build on work being done now for LTE-Advanced, rather than reinventing the small cell wheel. In the Forum, activities which will feed into future evolutions of LTE networks include work groups looking at virtualization (and a new cooperation agreement with ETSI in that area) as well as work on alternatives approaches for aggregating spectral resources, including those that span licensed frequency and licensed-exempt systems.


3. Areas of contribution

The Small Cell Forum can certainly contribute to the 5G debate by tapping into its members’ developments and requirements, and feeding its knowledge out to the industry via its Release Program and co-operations with other organizations like ETSI, the NGMN Alliance, and the Wi-Fi Alliance.

It also has specific technology activities which can be useful and influential in defining small cell architectures for the next few years, as well as for post-2020. Some of these technologies will help to ensure that standards for dense networks are related to existing knowledge and to real world requirements.

There are six clear examples of areas where the Forum already has highly relevant activity, and which will be essential to any future dense small cell network architecture – whatever the specifics of the platform for 5G. These are all areas where robust, universal specifications will be critical for successful deployment, and where 5G will benefit from building on work that is already ongoing for LTE and even work done for 3G.

These six areas are:

• An ecosystem based on open standards to ensure multi-vendor interoperability even if specific implementations are diverse

• A heterogeneous and self-organizing architecture to support 5G approaches to cost efficiency and flexibility, and to be adaptable to future technologies or spectrum

• An agile architecture which can provide unity but with the flexibility to address future technologies and use cases, for example evolving to address the virtualization of the small cell layer into Physical Network Functions (PNFs) and Virtual Network Functions (VNFs)

• A modular solution framework that allows for diversity of application, and for competition across the ecosystem

• A common API (application programming interface) framework to encourage development of new and future services in an interoperable way, as well as practical experience of dealing with the alternative business models for small cells

• A track record of cooperating with other industry bodies to achieve integration with their platforms, as seen in the work on Wi-Fi integration. Harnessing multiple technologies in a harmonised way is likely to be an important element of 5G.

3.1 An ecosystem based on open standards to ensure multi-vendor interoperability even if specific implementations are diverse

At the early stages of a new architecture, standards are essential to ensure that new players and unforeseen applications can be accommodated easily. They are also vital to support a competitive ecosystem, which breeds cost efficiencies and innovation.

The Small Cell Forum has a valuable contribution to make because it has strong experience of creating open frameworks which enable hardware and applications from many players to interoperate. These specifications can be fed into formal standards if appropriate. The Iuh specification was a good example of an open specification which ticked the three boxes that will be essential for 5G frameworks:

• It was driven directly by operator requirements for multi-vendor systems


• It enabled full interoperability of small cells from any compliant vendor, and so drove competition and innovation

• It became the basis of a formal 3GPP standard, speeding the process of official standardization and avoiding reinvention of the wheel.

The same three criteria must be met by specifications and frameworks which are being devised now for next generation LTE and 5G networks. This is not just about connectivity, but the systems that will be used to design, implement, manage and monetize the new networks. For instance, specifications like the TR-196 management data model could be extended to ensure common management of any kind of small cell design that emerged in 5G, without starting from scratch. TR-196 is a Broadband Forum specification which forms the basis of standardized remote management of small cells.

Many of the issues it addresses – plug-and-play operations, remote control of large numbers of physical small cells from different vendors - are being leveraged by the Forum in its definition of a virtualized small cell and will be even more relevant in 5G which is expected to be based around extremely large numbers of small cells, or physical network functions, in various environments.

3.2 A heterogeneous and self-organizing architecture to support 5G approaches to cost and flexibility, and to be adaptable to future technologies or spectrum

Standards-based connectivity and management are essential, but will not be enough on their own to support the very dense networks envisaged in 5G. For those to be efficient and economically viable, they will also need to be largely self-organizing. It will not be practical to plan and adapt every cell in an ultra-dense network manually, and in addition, it is expected that future architectures will be highly flexible and responsive – they will need to optimize themselves on a continuous basis, to deliver the most targeted and cost-effective capacity exactly where it is needed at any one time.

As the NGMN Alliance paper puts it: “The 5G system should reduce the complexity of the tasks of planning, configuration and optimization of the whole system. In particular, the 5G system should allow for easy deployment and management of massive numbers of small cells with features, like plug and play, self-configuration, optimization and healing.”

The Forum has a wealth of knowledge and effort to contribute towards that goal. The work that it has already done on self-optimizing networks (SON) for dense networks will be an important foundation for future developments and its technical efforts, and the real world experiences of its members, will both be helpful in defining next generation SON technologies and use cases.

In addition, SON methods will need to be interoperable and applicable to networks made up of base stations from different vendors, and running different technologies and frequencies. The Forum has defined a SON API [4], which enables SON functionality in small cells to be integrated into larger HetNets that include multi-vendor small cells and macro-networks. It defines high-level procedures which allow the exchange of information between different SON platforms – for instance between a centralized and a distributed system.

It will be important to build on this work and extend the functionality, as denser SON-enabled networks start to be deployed, as base station functions become more


virtualized and as the functions of SON diversify with LTE-Advanced and then 5G. In future, SON will have to be more dynamic, automatically adapting to changing conditions. Ultra-dense networks will not be able to be carefully planned as networks are now. Instead, there will be massive uncoordinated and ad hoc deployments.

Any standards will have to be sufficiently agile to support such new approaches and to support the overall principle of a dynamic, fluid, coordinated and self-optimizing architecture, whatever the specifics of the technologies that enable that in future. Only a dense network with these general qualities will be able to support the huge rise in traffic, but also to fulfill other 5G criteria such as dramatically lower cost of ownership and power consumption, and the flexibility to target capacity where it is needed, on an on-demand basis.

An important aspect of this will be virtualization, initially of the core network functions which control small cells, and then of the access network itself. The Forum has a new and broad cooperation with ETSI, focused on virtualization. Such work will feed into 5G discussions, as well as helping to establish some important principles immediately – for instance, that the barriers to entry for very dense small cell networks, whether LTE or beyond, can be lowered if small cell core network functions are virtualized in a standard way based around ETSI’s NFV architecture framework.

The Small Cell Forum believes that its own virtualization study, which focuses on the non-ideal fronthaul networks which are commonly found in small cell deployments, is highly applicable to 5G scenarios too. This study builds on the NGMN Alliance’s earlier work on RAN evolution, and is looking at alternative functional decompositions that are suitable for transport over non-ideal fronthaul. The study is currently focusing on alternative splits including PDCP-RLC, Split MAC, MAC-PHY and Split-PHY as a function of fronthaul characteristics.

The Forum is urging the NGMN Alliance to include access system virtualization over non-ideal fronthaul as a topic within its 5G initiative, and this is an area where it could provide valuable contributions and collaboration.

3.3 An agile architecture which can provide unity but with the flexibility to address future technologies and use cases

One of the most important and bewildering aspects of 5G is that so little is known, at this stage, about how it will look. While it is the right time to start considering the requirements of a next generation network, any work must be able to support technologies and use cases which may emerge in the 2020s or beyond.

“One of the key characteristics of 5G networks will be the support of an extremely high variety of requirements in connection properties and attributes, driven by coexistence of very different use cases,” says the NGMN Alliance.

The need for agile standards is not just about being prepared for an unknown future, but being sufficiently flexible to support a wide diversity of use cases with different priorities. A good example is the trade-off between low latency and reliability. While swift response to queries from wearables – important in some next generation user interfaces - will be reliant on extremely low latency, a smart meter application will prioritize reliable transmission of data, even in difficult RF environments (through walls or basements for instance). The latter, therefore, may tolerate the delays caused by re-transmissions of data when errors have occurred, typically using MAC-layer based HARQ (hybrid automatic repeat request).


Future evolutions of the MAC-layer and HARQ are likely to be an element of 5G, and can be an important tool to improve overall link robustness and reliability, especially when dealing with the autonomous operation of huge numbers of unplanned nodes. However, HARQ re-transmissions are a key source of latency and jitter and so can impact on user experience. In 4G, normal HARQ processing time delay is 4ms so a retransmission requires 8ms (and there may be several repeats depending on signal strength, congestion and interference). Conversely, the same HARQ timing requirements constrain the characteristics of the fronthaul transport network.

This limits the options for small cells in deployments which are reliant on ultra-low latency, including some virtualization approaches. And of course, one of the core objectives of 5G is to reduce latency to less than 1ms, at least for certain use cases such as some machine-to-machine services, and emerging ‘tactile networks’ which will support ultra-responsive applications like vehicle control and some interactive and virtual reality games. These extreme requirements may result in scenarios where the entire core network needs to be virtualized and co-located with the small cell.

In other words, the Forum believes 5G efforts need to provide unity but not be too narrow in their prescriptions, since there will be so many types of services with different requirements. Active input from operators and the ecosystem, as enabled by the Forum’s workgroups and Release Program, can help to identify those use cases, and the different approaches which will need to be supported in 5G.

3.4 A modular solution framework which allows for diversity of applications, and for competition across the ecosystem

This is another important area where the Forum’s approach and existing work supports the directions laid out by the NGMN Alliance. The latter’s white paper says: “In the sense of connection attributes provided to the end user, 5G should enable openness and multivendor capability at all levels and introduce modular provisioning concept. It means that the key connection attributes (e.g. mobility, security & privacy, reliability, bandwidth, latency etc.,) should be enabled/disabled/modified and controlled in a programmable and switchable manner, depending on particular use case and associated policy defined by the operator.”

If a new set of standards is to meet all the wide range of use cases that may emerge for 5G networks, and have the longevity which will justify investment, flexibility must be the watchword. Since many elements cannot yet be foreseen in detail, the goal must be a modular framework – a skeleton into which many hardware and software elements can be slotted in and out as the demands on the network change and technology evolves.

This kind of flexible, modular architecture is already at the heart of small cell thinking. The Forum has experience of driving this modular approach through its SCAPI (Small Cell Application Platform Interface) initiative, which was created for 3G and 4G generations to encourage competition and innovation. A modular approach supports the critical goal of interoperability, as outlined above, and gives deployers and the ecosystem the confidence that they will not be left in technology dead ends.

One of the most solid assumptions about 5G is that it will be based around a set of network APIs that will be open to all. That process has been seen in recent years as operators and vendors have opened up their internal APIs to partners and even competitors, to broaden the ecosystem around their platform and compete more effectively with the open environment of over-the-top providers.


It is early days for this significant industry shift, but the Forum has played an important role with SCAPI (3G SCAPI [5] LTE SCAPI [6]), which provides common APIs around which suppliers of each component of the network – hardware, platform software and applications – can compete, as illustrated in Figure 3-1.

This follows the long engineering tradition of ‘interchangeability of parts’ to ensure that vendors can harness new silicon and software advances with minimal entry barriers and custom re-engineering. These include interfaces for service discovery, GPS, PHY mode control, security coprocessor, datapath and others. These developments will provide valuable foundations and experience in the work of creating APIs for 5G, where even greater flexibility will be required.

Figure 3-1 The 3G Small Cell Application Platform Interface structure

Source: Small Cell Forum

3.5 A common API (application programming interface) framework to encourage development of new and future services in an interoperable way

Just as a common interface definition allows for interoperability between competing hardware implementations, so a common software framework is needed to encourage diverse applications, which can still easily interwork. This is a goal stated by the NGMN Alliance white paper and other 5G initiatives, including the European Commission-backed 5G-PPP, whose own initial document, ‘5G Vision’, says that “5G design will ensure high flexibility and be driven by a service approach ... Since 5G will enable new business models in a programmable manner, APIs should be available at different levels (resources, connectivity and service enablers) to support a variety of network and service application developers.” [1].

As well as SCAPI, the Small Cell Forum’s services working group is in the process of defining a standardized set of APIs (in cooperation with the Open Mobile Alliance) in areas such as content management and precision location, which can enable new services and use cases that harness those technologies. Again, this is an approach


which will be important in 5G, and which sets the stage for the kind of cooperation between different standards bodies and industry alliances that will be essential to achieve widely accepted and broad-ranging platforms.

Such cooperation is already underway, with an eye on 4G evolution as well as 5G. For instance, the Forum is working with the Open Mobile Alliance (OMA) to develop API standards for small cells in order to reduce time to market for new or enhanced applications which harness the technology.

In another example of a cooperation that will feed into 5G, the services working group has described architectures where services and applications can co-reside with the small cell itself, and those concepts have been integrated into the new ETSI industry specification group focused on mobile-edge computing (MEC).

This is just one example of how the Forum’s particular focus and experience could feed into the area which, ultimately, will decide 5G’s success – value creation for operators, their customers and the whole ecosystem. The Forum was founded from the start to focus on real world use cases and to define interfaces and frameworks based around those. For instance, in its enterprise small cell business case work, it modeled in detail how operators could enable small and medium businesses to mobilize their processes using small cells. In all areas of the technology, the Forum has long experience of discussing and advising on business cases and pragmatic operator requirements – which is not true of all standards bodies and alliances. This dose of realism will be essential to ensure that 5G stays wedded to reality and the prospect of future revenue and profit, and not just to ‘visions’.


4. Conclusion

This is the right moment to separate 5G hype from reality, and to start the discussion of how real operator requirements can be translated into new network standards, for the next evolutions of 4G as well as for a brand new generation. The NGMN Alliance has made a valuable contribution with its detailed outline of end-to-end service provider requirements for 5G, and that will be the basis for significant work by other industry organizations.

The Small Cell Forum intends to be prominent among those bodies, because of the unique contribution it can make to 5G discussions and developments. One of the few features of 5G on which there is broad consensus is that it will be built around very dense networks of small cells. That has many implications for future standards, including the need for new levels of cost and power efficiency, self-organization, dynamic capacity allocation and automation. These issues are already visible in 3G and 4G small cells, however, so the Forum will be able to draw on existing real world work and experiences in order to inform 5G initiatives, while reflecting the requirements and concerns of its operator members as they move towards a new generation of dense deployments.


References

1 NGMN 5G White Paper, NGMN, February 2015 2 CMCC, Dr Chi-Lin I, ‘Vision 2020: Perspective and Progress of CMCC’, September

2014 3 Volker Jungnickel et al, ‘The Role of Small Cells, Coordinated Multipoint and

Massive MIMO in 5G’, IEEE Communications Magazine, May 201 4 [SCF083] ‘SON API for small cells’, http://scf.io/documents/083 5 [SCF048] ‘3G SCAPI’, http://scf.io/documents/048 6 [SCF082] ‘LTE eNB L1 API definition’, http://scf.io/documents/082

http://scf.io/documents/083



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Small Cells and 5G Evolution