Communication networks beyond the capacity crunch

The impact of capacity growth on national telecommunications networks

Professor Andrew Lord, BT

Abstract

The rise in demand for capacity from consumers and businesses continues to grow exponentially as it has done for decades. Access technologies can in principle meet this demand at the user end, leaving a large bandwidth challenge in the rest of the network, constrained by ever tighter energy and economic constraints. Ubiquitous IP-based statistical multiplexing and content caching alleviate this challenge to some extent, despite changes in user behaviour towards high-end video based content streaming. This talk will take account of all these factors, give an appreciation of overall network design and will attempt to guide the debate towards the key problems to be solved if current internet growth is to continue for the next 10 years and beyond.

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Emerging applications and challenges

Dr Chih-Lin I, China Mobile Research Center

Abstract

Mobile Internet and the Internet of Things have been widely recognized as the two major driven forces of next generation mobile networks. Extensive investigation has been carried out across the ICT community to explore emerging application scenarios, define respective key performance requirements, and identify potential system design as well as key technologies. Recently, the concept of ‘Internet+’ and ‘Industry V4.0’ inspires another wave of discussion on ‘when Internet meets traditional industry!’. This presentation will share our perspective on emerging applications towards the year 2020 and corresponding technical challenges, followed by our understanding on the solutions to these challenges.

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Future traffic demand and characteristics from a media perspective

Mr Chris Chambers, BBC

Abstract

Providing topical information and entertainment began with wall paintings, the spoken word and face to face performance, then the addition of the written and printed word along with illustrations and pictures followed by audio recording. In the early 1920s, regular broadcast radio services began followed by television in the late 1930s and this has provided the basis of broadcast media we know today. These innovations frequently pushed boundaries and challenged the status quo but not all of these challenges were technical by any means. However, it could be argued that the development of accessible technologies has been fundamental to the successful deployment of information and entertainment media in all its forms throughout history.

Today, the merging of audio and video media with a whole range of digital services is becoming common place. With the ability of such services to develop new approaches in supporting people’s everyday living experiences, this will take communication networks into a new era central to the way we live.

This paper postulates that the historical trends with audio and video media developments from the early 1900’s will continue to push future boundaries and attempts to highlight the key demands and the developing trends from a communication network point of view.

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The social value of high-bandwidth networks: the case of creative performance

Professor Robin Mansell, London School of Economics

Abstract

One challenge of constructing widely accessible high bandwidth networks is the development of use cases confirming widespread demand across scientific, educational, and other groups.  In this presentation the focus is on demand from communities that are seeking to create distributed, simultaneous online artistic performances. Their requirements for extremely low latency in networks and for bespoke software applications means that meeting their demand requires investment in technology, but this is not the only barrier to greater use in this applications area. This presentation also emphasizes the organizational and cultural constraints they face in creating social value through online use of high bandwidth networks.

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Energy challenges in access and aggregation networks

Professor Dan Kilper, University of Arizona, USA

Abstract

Scalability is a critical issue for access and aggregation networks as they must support the growth in both the size of data capacity demands and the multiplicity of access points. Prevailing communication paradigms are reaching physical limitations that make continued growth problematic. Challenges are emerging in electronic and optical systems and energy increasingly plays a central role. For electronic systems in particular, as the density and speed increases, the total system energy, thermal density and energy per bit is moving into regimes that become impractical to support. We examine communication network scaling and energy use from the Internet core down to the computer processor core and consider implications for optical networks. Optical switching in data centres is identified as a potential crucible from which scalable access and aggregation networks for the future Internet will emerge.

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Implications of information theory in optical fibre communications

Professor Erik Agrell, Chalmers University of Technology, Sweden

Abstract

Information theory predicts that all channels have a limited information-carrying capability, depending on the available transmission resources. Therefore, the steady improvements in high-speed data transmission over optical fibres that have been achieved in recent decades will eventually stall. This tutorial presentation provides the information-theoretic background for this expected saturation. The theory dates back to 1948, when Claude Shannon established mathematical relations between information capacity, reliability and energy. Shannon showed that reliable communication can be achieved even over noisy channels, thereby setting the scene for today's era of digital communications. He also quantified the maximum data rate, in bits per second, for which this is possible: the channel capacity. These fundamental concepts are reviewed in the presentation, along with their implications in fibre-optical communications. Indeed, information theory not only predicts a limited capacity, it also provides insights into how transmission resources should in principle best be exploited, and thus may serve as a guide for where to look for better ways to squeeze more out of a precious resource.

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Cooperation and information replication in wireless networks

Professor Leandros Tassiulas, Yale University, USA

Abstract

A significant portion of today's network traffic is due to recurring downloads of a few popular contents. It has been observed that replicating the latter in caches installed at network edge - close to users - can drastically reduce network bandwidth usage and improve content access delay. Such caching architectures are gaining increasing interest in recent years as a way of dealing with the explosive traffic growth, fuelled further by the downward slope in storage space price. In this talk, we provide an overview of caching with a particular emphasis on emerging network architectures that enable caching at the radio access network. In this context, novel challenges arise due to the broadcast nature of the wireless medium, which allows simultaneously serving multiple users tuned into a multicast stream, and the mobility of the users who may be frequently handed-off from one cell tower to another. Existing results indicate that caching at the wireless edge has a great potential in removing bottlenecks on the wired backbone networks. Taking into consideration the schedule of multicast service and mobility profiles is crucial to extract maximum benefit in network performance.

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Obstacles to achieving high utilisation

Professor Scott Kirkpatrick, The Hebrew University of Jerusalem, Israel

Abstract

In communications the obstacle to high bandwidth and reliable transmission is usually the interconnections, not the links. Nowhere is this more evident than on the Internet, where  broadband connections to homes, offices and now mobile smartphones are a frequent source of frustration, and the interconnections between the roughly 40,000 subnetworks (ASes or autonomous systems) from which it is formed, even more so. The structure of the AS graph that is formed by these interconnections is unspecified, undocumented and only guessed-at through measurement, but it shows surprising efficiencies. Under recent pressures for network neutrality and openness or 'transparency',  operators, several classes of users, and regulatory bodies have a good chance of realizing these efficiencies, but they need improved measurement technology to manage this under continued growth. A long-standing vision, an internet that measures itself, in which every intelligent port takes a part in monitoring, can make this possible, and may now be within reach.

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New optical fibres for high-capacity optical communications

Professor David Richardson FREng, University of Southampton, UK

Abstract

For the past 30 years communications research has focused on finding innovative ways of coding and multiplexing optical signals to unlock the maximum practical ~10Tbit/s/Hz spectral efficiency provided by single-mode optical fibre. However, cost-effective future scaling of network capacity may ultimately benefit from fibre solutions that can exploit multiple spatial modes within a single multimode-core, and/or multiple cores incorporated within the fibre cross-section to increase the per-fibre spectral efficiency. This talk will review progress towards realizing these new fibre types (along with the key component/subsystems required) and describe the necessary requirements for ultimate commercial deployment.

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The benefits of convergence

Professor Gee-Kung Chang, Georgia Institute of Technology, USA

Abstract

We envision a versatile, multi-tier radio access technology that combines the strength of optical and wireless access networks using integrated microwave photonics and radio over fibre techniques for wireless data signal generation, transport and processing in a converged network architecture. All radio spectrum from 0.1 GHz to 100 GHz will be used to deliver multi-service with high capacity, low latency, carrier aggregation, resource sharing and management for heterogeneous mobile communications.

The integrated fibre wireless access network architecture will harness higher bandwidth efficiency through both provisioning frequency reuse and operating at higher frequency bands. Coordinated multi-point (CoMP) and multi-tier cell transmission and joint signal processing are needed to eliminate throughput bottleneck at the cell-edge in an integrated 4G and 5G system platform. The main goals of the converged optical and wireless access network is to manage and allocate varied network resources in real time (< 1ms) to maintain balanced network throughput while taking into account physical-layer connectivity constraints regardless of the underlying network topology by abstracting network nodes into shared, selectable, virtual functional blocks that includes wavelength, time scheduling, RF/mmW channel frequency and bandwidth, carrier aggregation and scheduling, latency, virtual resource status map through coordinated real-time communications. Agility and resource sharing in such aggregated physical scheme are the key to provide physical layer agnostic interfaces and network function virtulization. The benefits harvested from this new converged network architecture can meet the challenges in system scalability for capacity, wireless link speed, while overcoming the bandwidth crunch for next generation communication networks.

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Maximising the optical network capacity

Professor Polina Bayvel FREng, University College London, UK

Abstract

Most of the digital data is carried by optical fibres, forming the great part of the national and international communication infrastructure. The information carrying capacity of these networks has increased through wavelength division multiplexing, advanced modulation formats, digital signal processing and improved optical fibre and amplifier technology. This sparked the communication revolution and the growth of the Internet, and created an illusion of infinite capacity being available. But as the amounts of data increase, is there a limit to the capacity of an optical fibre communication channel? The optical fibre channel is nonlinear, and the intensity-dependent Kerr nonlinearity limit, sometimes called the nonlinear Shannon limit, has been suggested as a fundamental limit to optical fibre capacity. There has been much debate as to whether this is too pessimistic.  Current research is focused on finding linear and nonlinear techniques, both optical and electronic, to understand, unlock and maximise the capacity of optical communications in the nonlinear regime. This talk will describe some of them and discuss future prospects for success in this area.

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Physical limitations to network capacity

Dr René Essiambre, Alcatel-Lucent, USA

Abstract

In the last three decades, the maximum rate of transmission of information, or capacity, demonstrated over single-mode fibres has increased by an astonishing four orders of magnitude. In the last few years however, experimental demonstrations of fibre capacity seem to show capacity saturation just above 100 Tbits/s for 10 THz of amplification bandwidth. This transmission rate corresponds to approximately half the current nonlinear fibre capacity limit estimate of single-mode fibres over the same bandwidth. To achieve further progress, it is important to understand the physical effects and associated degradation mechanisms that can lead to capacity limitations in future fibre-optic communication systems. Furthermore, the role of fibre design on ultimate fibre capacity and the potential of novel transmission fibres, including fibres supporting multiple spatial modes, to increase capacity per fibre strand need to be considered.

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Enabling deep programmability in optical networks

Professor Dimitra Simeonidou, University of Bristol, UK

Abstract

This talk will attempt to shed light on potentials and benefits of combined software (SDN, NFV) with novel optical hardware solutions as the basis for enabling optical layer programmability for telecommunication, cloud and smart city infrastructures. Enabling SDN and NFV to support optical networks can provide a new open framework that can potentially facilitate network virtualisation, application specific network functions at the optical layer as well as coordination and orchestration of higher layers and applications with the optical layer. In parallel with the aforementioned software trends, programmable network technologies are rapidly emerging, which can utilise pluggable photonics and electronics to synthesise on demand hardware platforms. Combining new software and hardware capabilities will provide an opportunity for creating unique solutions that allow full application programmability of the optical networks.

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Integrated switching and transport

Dr John Dunne, Tek Strategy Consulting, Ireland

Abstract

The continuous demand for faster and higher quality networks is finally pushing packet processing electronics to their limits as the transmission speeds reach hundreds of Gigabits per second. This is also true of packet switching systems which cannot today process packets at the same speeds as the transmission systems. Is this the time for the optical layer of the network to assume more than just a static transmission role? This talk examines the commercial context that is pushing data centres out closer to the end user in the search for a competitive edge in quality, particularly for Content Distribution Networks. It looks at the future role of the optical layer, in particular can it combine transport and switching capabilities to create simpler and higher quality networks at the speeds that future generations will require.

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Cross layer decentralisation

Professor Jon Crowcroft FREng FRS, University of Cambridge, UK

Abstract

Today's networks are suffering from capacity constraints, not necessarily in the core, but sometimes in backhaul. However, who suffers most are users, and their quality of experience with wireless access performance (sometimes impacted by backhaul limits) being highly variable, patchy, and more crucially for many users and applications, latency and availability. It is the hypothesis of this talk that the solution to this problem is not ‘more bandwidth everywhere soonest’. The solution is massive decentralisation of networking, processing and storage. The idea of direct device to device comms (LTE direct, or WiFi Direct) and cooperative relaying, the ideas of personal cloud, and peer-to-peer storage, are not new. The point is that they have to become mainstream, engineered for (more) predictable performance, and to avoid systemic (e.g. emergent) failure modes. The challenge is to embed this thinking in transferring research results into future systems designs, and associated standards.

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