Insufficient spectrum available for dedicated 5G service allocation

  • Spectrum sharing essential, will reduce requirement by 75%
  • Regulatory work must begin immediately to unlock €141 billion in benefits, 2.3 million jobs
  • Real Wireless analysis a key part of a ground-breaking EC socio-economic study

3 October 2016, London UK – Europe risks not having sufficient spectrum for 5G service providers to deliver potential economic benefits of €141 billion and 2.3 million jobs if we continue to follow the conventional dedicated spectrum allocations per operator. This is the headline finding of a new analysis from a team that included independent wireless experts Real Wireless, published today as part of the European Commission’s landmark 5G socio-economic report.

The report recommends that the challenges presented by spectrum sharing must be addressed as early as possible in the development of 5G if the full socio-economic benefits are to be enjoyed.

The analysis examined the minimum spectrum requirements for 5G to service all users based on traffic demand calculated from high-density scenarios associated with three challenging key use cases – healthcare, utilities, and motorways. The report finds that supporting the highly demanding 5G applications proposed under the 5G vision, especially in the multi-gigabit connectivity environment of congested major motorways, would require larger quantities of spectrum to be available than is currently earmarked for allocation. Capacity and therefore spectrum demand is driven mainly by passengers in the connected vehicles, streaming content onto future (2025–2030) user devices.

By considering a variety of spectrum-sharing scenarios, the analysis demonstrates how these requirements can be reduced by up to 75% in any given environment. The outcomes suggest that society as a whole will benefit if sharing in all frequency sub-ranges, particularly in the sub-6GHz ranges, is made possible.

In ultra-reliable connectivity environments, such as eHealthcare where there is safety of life implications, this needs to sit in sufficient dedicated spectrum to meet the SLAs of certain applications.

Real Wireless also highlighted three further possible approaches to reducing the amount of spectrum 5G would require. These included dynamic adjustment of media resolution, reducing levels of spectrum over-allocation to a limited number of parties, and the rollout of smaller-sized cells. It acknowledges that a balance would need to be struck between capacity requirements and economic factors, but its analysis demonstrated that the latter two approaches alone could contribute to an additional 86.7% reduction in the amount of spectrum required by 5G.

“The socioeconomic value of 5G will be found in its applications for vertical industries to an extent that no wireless technology has before,” said Mark Keenan, CEO, Real Wireless. “However many of those applications identified under the 5G vision are highly demanding, with significant spectrum requirements.”

“The success of 5G therefore requires legislators and regulators to begin investigating spectrum allocation and sharing principles as soon as possible to help overcome any challenges well in advance of the technology being deployed. Only then will the wireless industry be able to develop policy, tools and strategies that can drive market confidence in the essential spectrum-sharing methods we have outlined in our study.”

The results of this analysis were presented as part of the European Commission’s eagerly anticipated year-long study into the socioeconomic benefits of 5G to Europe. With input from more than 150 experts, it forecasts the realities that will arise from utilising 5G’s capabilities in 2025 and 2030 – and the potential socio-economic benefits this will generate.

The European Commission’s full socio-economic report is available to view via its website.

About Real Wireless
Real Wireless delivers independent, informed and innovative advisory services in every aspect of wireless, including strategy, detailed technical and economic studies. The company works with mobile operators, governments, venues, building owners, vendors and regulators to bridge technical and commercial domains to help its clients get the best from wireless. With experts in every aspect of wireless and a proven track record, Real Wireless is one of the world’s leading wireless advisory firms. Its clients include Ofcom, Wembley Stadium, The England and Wales Cricket Board (The ECB), BAA, The European Commission, major network operators, vendors and many others.

For more information visit or follow the company on Twitter at @real_wireless

PR contacts
Andrea Berghäll/Sanjay Dove
+44 208 408 8000

Bad neighbours? A comparison of LPWA technology options

Screen Shot 2016-05-11 at 10.24.43While the carrier community is celebrating the steady arrival of 3GPP defined cellular IoT that will enable the use of existing GSM networks with minimal impact through upgrades, there remains significant interest in alternative solutions in the unlicensed space.

Some of this interest comes from service providers who lack access to licensed spectrum, but the majority is being driven by use cases where the long range, extended battery life, and very low cost of Low Power Wide Area (LPWA) wireless technologies is a fundamental necessity. What is emerging though is a fragmented area of largely proprietary solutions, making it difficult for users to decide on which option best suits their particular use case.

The key approaches to unlicensed M2M connectivity can be split in to two groups: UltraNarrowBand (UNB) technologies; and those that employ some form of spread spectrum modulation (SSM).

Growth forecasts for the M2M market underline the need for these LPWA systems to be able to co-exist in license exempt spectrum and that any LPWA solution should be able to support  many connected devices – and this requirement is only going to become more important over time as the number of devices increases.

Real Wireless recently carried out a study that compared the levels of interference between networks using these two different physical layer architectures. This required us to model a scenario in which a UNB and a SSM network had overlapping coverage areas and various other sources of interference, including non-LPWA users, in order to study the ability of both technologies to mitigate interference.

This insight gained was that UNB and spread spectrum modulation networks can only effectively co-exist in very low capacity deployments. Shared channel operation, either between a SSM and a UNB network, or two SSM networks, would result in mutual interference and uplink blocking of both networks, except in cases of very low simultaneous user numbers.

In other words, the reality is that a SSM LPWA network architecture should be considered a ‘bad neighbour’, and multiple unlicensed IoT networks can only effectively share access to spectrum when they all also share a UNB architecture. However, given the number of use cases for these technologies, they will undoubtedly coexist in one location. As a result, this study has significant implications for technology choices in this important growth market.

To find out more about our study and approach to modelling of unlicensed IoT solutions, download our new white paper today.

New study finds latest PMP can deliver almost twice the ROI for MNOs and ISPs compared to traditional last-mile infrastructure

Real Wireless modelling reveals the total cost of ownership of different last-mile data transport technologies for backhaul and enterprise access

London UK, 19 January 2016 — The latest point-to-multipoint (PMP) last-mile solutions can reduce backhaul total cost of ownership (TCO) by as much as 50% and generate 1.8x higher return on investment (ROI) for enterprise access. These are some of the findings from the new Real Wireless report into the cost and time to breakeven of last mile data transport in multiple deployment scenarios.

The study, carried out by independent wireless experts Real Wireless, looks at the TCO of installing and running backhaul networks based on a range of wired and wireless technologies. Analysis found that site-related costs dominate TCO, accounting for around half of a five year TCO. The report revealed PMP solutions offered up to 50% TCO savings over point-to-point (PTP) and managed fibre, largely due the aggregation of multiple links to a single hub site.

For the study, Real Wireless modelled a case study of an ISP, building out a network to supply carrier-grade connectivity to enterprises. It found that PMP microwave and sub-6 GHz resulted in the fastest time to break even, potentially enabling an ISP to connect 67% more customers and generate 1.8x higher ROI compared to PTP equivalents. The report also highlighted the increased revenue possible with PMP at licensed microwave frequencies; this can generate a further 30% higher ROI than PMP in sub-6GHz bands. The increased revenue of PMP microwave was due to its ability to offer both higher capacities and a superior grade of service than its unlicensed equivalent. The ISP model can equally apply to a mobile operator’s network division, where the higher ROI equates to greater financial efficiency and more ability to invest in network footprint.

“The new report highlights the variety of last mile technologies available and how the right choice can almost halve a network’s TCO.” said Oliver Bosshard, Managing Consultant, Real Wireless. “It’s clear from the report that MNOs and ISPs should carefully consider the knock-on impact their choice of technology will have for their future revenues and growth. Particularly in enterprise deployments, operators and ISPs should look carefully at the latest available transport options to determine what will deliver the best business case.”

Managed fibre networks, albeit scalable to higher capacities, were found to have a significantly higher TCO when compared to wireless approaches. PMP solutions were also shown to offer a much quicker ROI versus PTP solutions, because PMP lends itself to the sharing of hub sites and bandwidth between customer terminals. However, PTP links were found to more suitable for longer links and lower site densities.

Real Wireless considered a range of transport options for the study, including managed fibre, V-band and E-band PTP, microwave PTP and PMP and sub-6 GHz unlicensed PTP and PMP. The model includes not only the initial outlay for equipment but also the more significant aspects of installing and running it over time.

The full report is available to download for free from the Real Wireless website.

Real Wireless enhances strategic expertise with new CTO

Simon FletcherIndependent expert continues to bolster management team by hiring Simon Fletcher from NEC Telecom Modus

London UK, 18th November 2015 – Leading independent wireless advisory Real Wireless has recruited Simon Fletcher as chief technology officer.

Simon joins Real Wireless from NEC Telecom Modus and brings an impressive range of experience to the role, particularly in team management and strategic business development. The appointment comes as two new recruits also join the business. Dr. Raymond Kwan joins the company’s technology practice from Cisco (Ubiquisys), and John Stephens joins the deployment and lifecycle practice, drawing on his background in wireless system rollouts and planning at CommScope and Bluwan.

As CTO, Simon will take overall technical responsibility across the company as a part of the management team. Recognised as a regular speaker at industry events and currently acting as chairman of the Cambridge Wireless Future of Wireless Conference Organising Committee and Small Cell SIG Champion, Simon brings an enviable network of contacts to Real Wireless alongside a proven ability to lead teams in delivering technical projects while identifying and meeting new strategic goals for the wider business. His long standing association with the UK innovation eco-system as a director of mVCE and the Innovate-UK ICT-KTN brings a wealth of knowledge on the application of stratetgic research through open innovation to accelerate product and services delivery. In recent times his focus has been on future cities, the application 5G and IoT in industry verticals with an event horizon towards 2030.

“Simon is a talented and knowledgeable professional and a perfect fit for the company,” said Real Wireless CEO Mark Keenan. “In addition to assuming technical responsibility across the company, he will join as a member of Real Wireless’s newly strengthened management team. Here his leadership skills, detailed knowledge of sustainability strategy, and emerging technology insights will come together to help further build on the strength of the business, identify new potential value areas, and drive forward future growth.”

Simon Fletcher said: “As demand for wireless products and services continues to enjoy massive growth thanks to the 4G rollout, 5G development and the Internet of Things, to mention but a few areas, it’s a great time to be joining Real Wireless. The business has a great history of adding value to all parts of the wireless industry and end user eco-system, and I look forward to helping the company achieve its growth ambitions while building relationships with all of our existing and future customers.”

Simon spent the past 20 years working in the design and development of technical telecoms infrastructure. Beginning his career in technology demonstrators at Racal Radar Defence Systems, he moved to Telecoms Modus in 1999 to play a key role in the development of 3G products and in 2006 he established a core architecture team that helped develop the first-generation of technology for 4G systems culminating in a Steering Board position in the LTE SAE Trials Initiative (LSTI), a global forum with a mission to assure the early adoption of LTE. His long participation in Common Public Radio Interface (CPRI) defining early C-RAN concepts brings great foresight on an important architectural element of emerging 5G architectures.

About Real Wireless
Real Wireless delivers independent, informed and innovative advisory services in every aspect of wireless, from the technical to the commercial. The company works with mobile operators, governments, venues, building owners, vendors and regulators to bridge technical and commercial domains to help its clients get the best from wireless. With experts in every aspect of wireless and a proven track record, Real Wireless is one of the world’s leading wireless advisory firms. Its clients include Ofcom, Wembley Stadium, The ECB, BAA, The European Commission, major network operators, vendors and many others.

For more information visit
Twitter: @real_wireless

PR contacts
Sanjay Dove/Andrew Hill

+44 208 408 8000

Modeling the fair co-existence of LAA and Wi-Fi

By Julie Bradford

More often than not, the debate around the use of licence-exempt spectrum is driven by passion rather than analysis. After all, this is a debate whose impact goes beyond the technology choice, or financial impact; which technology is selected will set an important precedent for how unlicensed spectrum should be used.

It’s for this reason that we at Real Wireless were delighted that Cisco asked us to simulate and assess options for the co-existence of LAA-LTE and Wi-Fi, helping to redress the balance of the debate by introducing some cold, hard, technical data into the narrative.

At the heart of Wi-Fi’s success is the premise of fair co-existence, enabling multiple Wi-Fi system owners to deploy Wi-Fi access points in the same unlicensed spectrum in an unmanaged fashion. Service providers increasingly wish to also make more use of unlicensed spectrum in order to contribute to mobile system capacity, with one of several means of achieving this being Licensed Assisted Access (LAA-LTE).

Our work for Cisco was presented at the recent CEEC 2015 conference and forms part of their LAA-LTE contributions to 3GPP. Cisco’s contribution turns on a feature called listen before talk (LBT), of which there are a variety of different schemes available.

For this analysis, we used one of Real Wireless’s own, custom-developed tools – in this case, the Wi-Fi and LTE (WaLT) system simulator. Using this tool, we modelled co-existence performance between LAA-LTE and Wi-Fi when set up to use a variety of candidate LBT schemes. These interactions are highly complex, therefore a sophisticated simulator was required, the product of our collective experience and knowledge of modeling techniques.

The results of our simulations clearly demonstrate that the details of the choice of LBT scheme and settings of that scheme matter significantly to achieving fair coexistence.

This was a great project to be involved with, particularly as it gave Real Wireless and Cisco the opportunity to add a much more scientific voice to a hotly contested issue.

Download Fair Co-Existence of Licensed Assisted Access LTE (LAA-LTE) and Wi-Fi in Unlicensed Spectrum

Download Fair Co-Existence of LAA and Wi-Fi presentation »

European 5G socioeconomic study to evaluate the wider benefits of the next generation of wireless

Real Wireless, Tech4i2, InterDigital Europe and Trinity College Dublin to assess socioeconomic impact of 5G in Europe

London, UK – 9th June 2015 – A new study into the socioeconomic impact of 5G in Europe commenced on May 22nd, led by a group of industry experts and academics.

Undertaken in partnership with the European Commission, the main focus of the study is to develop a better understanding of the potential economic impact of 5G networks in new areas such as health and transport.  Research will examine the potential social benefits of the next generation of wireless technology and identify where 5G will make a difference.

The project will determine the key use cases for 5G, identifying their relative potential in terms of social and economic benefits in the European context. It will test the proposition that 5G can offer specific additional value over 4G to particular vertical user sectors, via work which will be fully informed by and consistent with the 5G PPP initiatives while offering a fresh and independent perspective.

The consortium was selected by the European Commission to bring its independent approach and wide knowledge of both commercial and technical aspects of wireless technology. The study will be carried out over 12 months by a consortium comprising:

  • Applied economic research consultancy Tech4i2
  • Independent wireless advisors Real Wireless
  • Wireless research and development company InterDigital Europe
  • The national telecommunications research centre in Ireland, CONNECT headquartered at Trinity College Dublin

The work will shed light on the journey to future deployment of 5G and its impact on economies across Europe, allowing stakeholders to plan effectively. The study will allow the European Commission to work closely with regulators to plan future policy in areas such as spectrum allocation planning and future market regulation.

“After working with the European Commission on several other key projects, Real Wireless is proud to be an integral part of realising 5G and its impact in Europe,” comments Professor Simon Saunders, Project Director. “The socioeconomic effects of this new generation of wireless will be unprecedented, and understanding these will be crucial in securing Europe as a global leader in 5G. The consortium we have assembled to work on this project offers a uniquely informed yet independent perspective on these issues.”

The study will be informed by inputs from stakeholders via a series of stakeholder hearings which will be held on 22nd September and via a workshop which will be held on 19th October, both in Brussels. To find out more about these events and follow project progress, join the project’s dedicated LinkedIn group at

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About Tech4i2

Tech4i2 is a UK based global applied research consultancy operating in the areas of innovation and inclusion.  Tech4i2 supports local and national governments and global organisations in strategic decision-making and service delivery improvement. The tech4i2 team and network of international experts operating in over 50 countries offers research excellence enabling the provision of incisive advice.

In the last five years Tech4i2 has undertaken more than 60 technology development projects with the European Commission, OECD, IOC and government organisations in Eire, Italy, Poland, Spain, UK and US.

To find out more about Tech4i2’s work on bandwidth and spectrum strategy and policymaking visit the Tech4i2 website.


About Real Wireless
Real Wireless delivers independent, informed and innovative advisory services in every aspect of wireless, from the technical to the commercial. It works with mobile operators, governments, venues, building owners and regulators to bridge technical and commercial domains to help its clients get the best from wireless. With experts in every aspect of wireless and a proven track record, Real Wireless is one of the world’s leading wireless advisory firms.

Its clients include Ofcom, Wembley Stadium, The ECB, BAA, The European Commission, major network operators and many others.

To find out more about Real Wireless and its work in 5G and wireless strategy and policy visit the Real Wireless site.

For more information visit

Twitter: @real_wireless


About InterDigital®
InterDigital develops technologies that are at the core of mobile devices, networks, and services worldwide. We solve many of the industry’s most critical and complex technical challenges, inventing solutions for more efficient broadband networks and a richer multimedia experience years ahead of market deployment. InterDigital has licenses and strategic relationships with many of the world’s leading wireless companies. Founded in 1972, InterDigital is listed on NASDAQ and is included in the S&P MidCap 400® index.

InterDigital is a registered trademark of InterDigital, Inc.

For more information on InterDigital’s work in 5G, please visit the InterDigital vault.


About CONNECT at Trinity College Dublin
CONNECT is Ireland’s national research centre for Future Networks and Communications. We are focussed on three major areas of research; Network-aware services, Service-aware networks and The Internet of Things. CONNECT is headquartered at Trinity College Dublin. It is jointly funded by Science Foundation Ireland and by industry. Today, CONNECT engages with over 35 companies including large multinationals, SMEs and start-ups. CONNECT brings together world-class expertise from 10 Irish academic institutes to create a one-stop-shop for telecommunications research & development and innovation.

Real Wireless joins 5G Innovation Centre

Wireless experts working with University of Surrey and industry’s biggest names to drive 5G development

London, UK – 20th May 2015 – Real Wireless has become a member of the 5G Innovation Centre (5GIC) at the University of Surrey, joining the industry’s biggest names in driving the development and evaluation of 5G. Bringing together leading academic expertise and key industry partners in a shared vision, the 5GIC will help to define and develop 5G infrastructure.

Heavily involved in the early stages of 4G, Real Wireless brings its independent expertise and experience to the 5GIC to advise on regulatory, technical and business challenges.

“While there’s still no agreement as to what 5G will look like, there are a number of different options currently on the table and it’s important that each of these are carefully evaluated and tested,” said Professor Simon Saunders, Director of Technology at Real Wireless. “Real Wireless is bringing independent expertise to the 5GIC and we’re really excited to be a part of the next generation of mobile technologies.”

Research at the 5GIC will drive the delivery of a mobile communications network capable of meeting the needs of tomorrow. The focus will be on developing intelligent systems that work together to give the impression of unlimited data capacity, providing a network that is far faster than today’s 4G system, with greater energy-efficiency and reduced end user costs.

“Real Wireless’ independent expertise is an excellent addition to the 5GIC and they join many of the biggest names in the industry in helping to shape the future of 5G,” said Professor Rahim Tafazolli, Director of the Institute for Communication Systems (ICS) and the 5GIC. “With their understanding of both the business and technical challenges of wireless, Real Wireless joins the first wave of SME members of the 5GIC.”

The 5GIC is part of the University of Surrey’s Institute for Communication Systems (ICS), drawing on its status as an internationally leader in satellite and terrestrial mobile communication systems knowledge. The ICS previously made a major contribution to the development of 2G technology in the 1990s, 3G in the 2000s and 4G since 2010.

About Real Wireless
Real Wireless delivers independent, informed and innovative advisory services in every aspect of wireless, from the technical to the commercial. It works with mobile operators, governments, venues, building owners and regulators to bridge technical and commercial domains to help its clients get the best from wireless. With experts in every aspect of wireless and a proven track record, Real Wireless is one of the world’s leading wireless advisory firms.

Its clients include Ofcom, Wembley Stadium, The ECB, BAA, The European Commission, major network operators and many others.

For more information visit
Twitter: @real_wireless

PR contacts
Darren Willsher/Andrew Hill
+44 208 408 8000

Carrier-grade Wi-Fi: a backhaul bottleneck by 2019?

Real Wireless was recently commissioned by Bluwan to analyse the emerging trends and technological challenges that carrier-grade Wi-Fi is creating.

The study, Carrying Carrier Wi-Fi: The Technology Challenges, emphasized the increasing reliance operators will be placing on carrier Wi-Fi over the next five years. In fact, our analysis reveals that carrier-grade Wi-Fi hotspots will make up more than 80% of all available access points in 2019.

The study also identified that data demands being placed upon Wi-Fi hotspots will increase dramatically in the coming years, driven by data-intensive applications like streaming content. In fact, according to figures from Cisco, the world’s hotspots will need to support a staggering 63 exabytes of Wi-Fi IP traffic each month by 2018.

While there is little doubt carrier-grade Wi-Fi will form a crucial part next generation mobile networks, operators need to be aware of how important effective backhaul provision will become. In particular, the affordability of backhauling such dense network hotspots will become an increasingly serious barrier.

To avoid this, our analysis identified eight key technology criteria that Carrier-grade Wi-Fi needs to meet in order to ensure they are both cost-effective and operationally efficient to deploy. These key criteria are:

  • < $1,000 per link
  • Flexible planning
  • Flexible capacity allocation
  • Low Total Cost of Ownership per Mbps
  • > 500Mbps throughput
  • High scalability
  • Low latency: < 10ms
  • Quality of Experience 

In the report, we then benchmarked a range of wireless backhaul technologies against these criteria to assess their suitability for tackling this challenge.

For more information on the findings, our full analysis, and our conclusions, please download a copy of ‘Carrying Carrier Wi-Fi: The Technology Challenges’ here.

A Manifesto for better DAS

DAS_Close_SMateoNote: This article, by Real Wireless’s Managing Consultant Oliver Bosshard, was originally published in RCR Wireless

The traffic demands users are placing upon networks continues to accelerate rapidly. In order to cope with this trend, debates have focused on network offload; the benefits, options available and their respective merits.

Despite plenty of discussion, we’re still no closer to solving this problem. 80% of all data traffic is generated indoors, from office employees, visitors, customers and the like. Yet remarkably few buildings feature indoor mobile infrastructure installations; typically only the newest and largest (e.g. airports, stadia, shopping malls), ignoring the vast majority of people. Clearly there is a huge opportunity here and a number of technologies are jostling to be the solution – including Small Cells, Radio Remote Heads, Wi-Fi and optical or passive Distributed Antenna Systems (DAS), each with their own merits, weaknesses and use cases. Ideally we would have one standardized solution with standardized interfaces for all (large to small) indoor coverage solutions.

The oldest solution for indoor coverage is DAS. Originally an analogue, single-operator, single-technology solution, it has evolved to encompass digital multi-operator, multi-technology solutions – as well as supporting MIMO (Multiple Input – Multiple Output).

Despite these upgrades there remain a number of significant limitations to the technology – and a lot of room for improvement. Worse still, it now faces stiff competition from rival technologies, in particular from small cells. A number of analyses show that these might be more cost-effective than DASinsome cases and some companies and pundits have been making announcements about the end of DAS. With the massive reduction of base station (BS) pricing, operators might even opt for more dispersed Base Stations (BS) with a passive DAS, instead of an active DAS.

But DAS continues to be used widely, and in fact the number of deployments continues to grow. No surprise: it has a lot of compelling attractions, especially for multi-technology and multi-operator support (they can share one infrastructure, as opposed to one small cell for each). Indeed, it was striking how at Mobile World Congress 2014 the explosion of activity and news came from DAS vendors, demonstrating a number of new products and innovative ideas.

Certainly, all is not lost for DAS. If it could continue to evolve into a smart, digital solution – offering flexible sectorisation, intelligent/dynamic capacity steering, digitalization, package switching at a more competitive price – it could become the ideal solution.

Here is my manifesto for a better DAS.

(Note: In the interests of complete fairness, several companies are currently working on – or planning – some of these ideas. However, I’m not yet aware of anyone that has announced they intend to combine them all, and I see this as the real opportunity here.)

Better RRUs through equipment adjustments

Compared to conventional radio remote heads, the radios used in the Radio Remote Units (RRU) of DAS are technology-agnostic. Typically RRUs will feature modular support for all 5 bands and technologies, and are remarkably straightforward in their composition: one power supply, one Fibre or Cat6/7 connection, one RF output to an antenna or passive DAS.

Ideally, the RRUs should evolve in to full 2×2 MIMO remote units. To achieve this, the equipment required needs to become slightly more complex, with 2 RRUs in tandem fed by two Fibres or Cat7 cables with two RF outputs to a MIMO antenna or DAS. If the total spectrum of both streams together is less than 270 MHz, only one Fibre / Cat 7 connection may be used.

Increase signal capacity and noise cancellation via digital transmission

At present, the fiber connections between Master Units (MUs) and Radio Remote Units (RRUs) typically support a sampled analogue RF signal input of up to 10 Gbps in capacity.

With 270 MHz of cellular spectrum available across all 2G to 4G bands and technologies, and 30 MHz of sampled spectrum typically requiring 1 Gbps of digital capacity, this means 9 of the 10 Gbps available is required for cellular; leaving only 1Gbps spare for other technologies such as Wi-Fi.

But sampling of an analogue RF signal is not the most efficient usage of a transport medium. Imagine if the digital bit stream from the CPRI interface could be used. The CPRI data stream does not need sampling and therefore can be transmitted as it is, using the transport medium in an efficient way. As a result, conventional fibre connections could be replaced with Cat7 cabling, in conjunction with standard SFPs on the MUs and RRUs.

The other benefit of digital transmission is that the digital signal can be transported, amplified and distributed without the typical signal losses and noise creation. This would mean that RRUs could be situated far away from the MU and daisy chained as required.

Finally, by digitizing the transmission, the current issues DAS faces with signal loss over distance are rendered irrelevant, as the signal can be amplified without the risk of increased noise. Thisalsostartstoleadtowardsahybrid between DASandthenewer CRAN architectures beingcontemplatedforthewide-areanetwork.

Reduce costs, simplify and increase efficiency by connecting to CPRI

At present, DAS uses standard RF interfaces for BS – MU connections. This results in OEMs needing to purchase and produce additional BS hardware for compatibility. This increases the complexity of the solution, whilst adding additional costs for manufacturing, stocking and shipping.

Using CPRI – oranotherevolvedoptimizedinteroperabledigitalinterface- would do away with the need to include the radio in the BS, reducing hardware requirements, power consumption and the use of external directional couplers and termination loads between the BS and the MU. The need for less up-conversion and final amplification in the base stations would reduce hardware costs, power, UPS and air-conditioning significantly and avoid RF noise creation.

Finally, by digitizing the transmission, the current issues DAS faces with signal loss over distance are rendered irrelevant, as the signal can be amplified without the risk of increased noise. This would mean that RRUs could be far away from the MU and daisy chained as required.

But at the same time, thanks to our newly supported CPRI connectivity, the signal conversion at the RRU end becomes simpler and cheaper, thanks to a direct digital / RF conversion.

Take full advantage of routing and switching capabilities

Another benefit of CPRI interface is that the data is presented as a digital data stream. As a result, the data stream could be switched and routed by proprietary switches supplied by the DAS manufacturers, using either Cat 7 (up to 100m) or Fibre networks for longer MU – RU distances (up to 40 km is possible).

Doing so would not only allow full flexibility in traffic allocation to end points, shaping traffic to meet demand for capacity, but also smarter switching of unused or underused repeaters. By manually or dynamically switching off unused repeaters, more effective management of uplink and downlink noise pollution and power consumption is enabled.

Unfortunately CPRI implementation differs from OEM to OEM: it is one of those “not quite standardized standards”. We need to achieve open interfaces and (perhaps) cross-vendor interoperability if we are to get the best possible use out of DAS and a more open market. In the meantime, DAS manufacturers can create their own CPRI at the master unit output, in order to take advantage of the benefits digital transmission offers.

Another issue is that CPRI, while digital, is not compatible with Ethernet or current installed networks.

That too is changing, however. While there are issues with carrying these signals for their transportation over standard TCP/IP switching and routing networks these can be addressed. By standardising the CPRI interface across OEMs and encapsulating the cellular data packets in standard IP packets, traffic could be switched and routed via conventional routers instead of proprietary units supplied by DAS manufacturers – of course, this is reliant upon transmission requirements being met, such as synchronization and a jitter free constant serial data streams. However, several vendors are now demonstrating products that can, indeed, carry digitized RF over standard Ethernet. 

By adopting these proposed changes, we would see massive capital and operational savings in the use of DAS systems. Standard infrastructure would be able to be used for switching and routing, whilst larger areas would be able to be covered by a DAS system.

To end with two thoughts about the implications for business models and the industry.

It is notable that these changes to DAS, coming from an in-building context are very similar to, and probably converge with, the activities around virtualization and Cloud RAN that are happening elsewhere in the network. Again, the move to transporting digital radio signals, to support multiple services in a flexible way are similar. We may see some intriguing overlaps between DAS companies and Cloud RAN suppliers.

Finally, and worth noting, the term “neutral host” may well receive a completely new meaning and present a new opportunity for groups such as MSOs. Interestingly, there has always been a difference in neutral host between Europe & USA, and that difference could change in various ways. Beyond cost and efficiency savings, the proposed changes could actually catalyse new business models that could change the industries structure.