Capacity Crunch Research Articles

Ultra-high-density spatial division multiplexing with a few-mode multicore fibre

Single-mode fibres with low loss and a large transmission bandwidth are a key enabler for long-haul high-speed optical communication and form the backbone of our information-driven society. However, we are on the verge of reaching the fundamental limit of single-mode fibre transmission capacity. Therefore, a new means to increase the transmission capacity of optical fibre is essential to avoid a capacity crunch. Here, by employing few-mode multicore fibre, compact three-dimensional waveguide multiplexers and energy-efficient frequency-domain multiple-input multiple-output equalization, we demonstrate the viability of spatial multiplexing to reach a data rate of 5.1 Tbit s−1 carrier−1 (net 4 Tbit s−1 carrier−1) on a single wavelength over a single fibre. Furthermore, by combining this approach with wavelength division multiplexing with 50 wavelength carriers on a dense 50 GHz grid, a gross transmission throughput of 255 Tbit s−1 (net 200 Tbit s−1) over a 1 km fibre link is achieved. A few-mode, multicore fibre allows ultra-high-speed data transmission on a single wavelength of light.

A Step-Size Controlled Method for Fast Convergent Adaptive FD-LMS Algorithm in Few-Mode Fiber Communication Systems

Space-division multiplexing using few-mode fibers (FMF) has emerged as a promising technology to overcome the next capacity crunch. The key challenges of FMF systems are inter-modal crosstalk due to random mode coupling and large differential mode group delay (DMGD). Adaptive frequency domain least mean square (FD-LMS) algorithm has been proposed as the most hardware efficient multi-input multi-output equalization method for compensating large DMGD. Except for hardware complexity, the convergence speed of the adaptive FD-LMS algorithm is another important consideration. In this paper, we propose a noise power spectral density (PSD) directed adaptive FD-LMS algorithm, which adopts variable step size to render the posterior error of each frequency bin convergent to the background noise in an additive white Gaussian noise (AWGN) channel. In a 3000 km six-mode transmission system with 35 ps/km DMGD, compared with signal PSD dependent FD-LMS method and conventional FD-LMS method, our new algorithm could improve the convergence speed by 36.1% and 48.3%, but their hardware complexity will only increase 10.7% and 17.2%, respectively.

Information Transmission Using the Nonlinear Fourier Transform, Part III: Spectrum Modulation

Motivated by the looming "capacity crunch" in fiber-optic networks, information transmission over such systems is revisited. Among numerous distortions, inter-channel interference in multiuser wavelength-division multiplexing (WDM) is identified as the seemingly intractable factor limiting the achievable rate at high launch power. However, this distortion and similar ones arising from nonlinearity are primarily due to the use of methods suited for linear systems, namely WDM and linear pulse-train transmission, for the nonlinear optical channel. Exploiting the integrability of the nonlinear Schr\"odinger (NLS) equation, a nonlinear frequency-division multiplexing (NFDM) scheme is presented, which directly modulates non-interacting signal degrees-of-freedom under NLS propagation. The main distinction between this and previous methods is that NFDM is able to cope with the nonlinearity, and thus, as the the signal power or transmission distance is increased, the new method does not suffer from the deterministic cross-talk between signal components which has degraded the performance of previous approaches. In this paper, emphasis is placed on modulation of the discrete component of the nonlinear Fourier transform of the signal and some simple examples of achievable spectral efficiencies are provided.

Making spatial multiplexing a reality

To avoid a 'capacity crunch', future optical networks will need to simultaneously transmit multiple spatial channels. For spatial multiplexing to be practical, the upgrade path from legacy wavelength-division multiplexed systems needs to be smooth and to consider integration-induced crosstalk from the outset.

Spatial Multiplexing in Fiber Optics: The 10X Scaling of Metro/Core Capacities

Optical networks have economically enabled an unabated exponential traffic growth over the past decades, with commercial wavelength-division multiplexed (WDM) systems carrying over 20 Tb/s of traffic per fiber, closely approaching the nonlinear Shannon limit. Looking at all physical dimensions available for further capacity scaling, it becomes clear that tapping into the spatial dimension is the only long-term scalable solution to overcome the looming optical network capacity crunch. As such, space-division multiplexing (SDM) is bound to become an important optical networking technology over the next decade. Integration of SDM components will be key in reducing cost, footprint, and energy consumption, while integration-induced crosstalk may be compensated through the use of digital signal processing similar to that of vectoring used in digital subscriber lines (DSL) or multiple-input-multiple-output (MIMO) techniques used in long-term evolution (LTE) wireless systems.

A Twist on the Capacity Crunch

A Twist on the Capacity Crunch

Optimized Parallel Transmission in Elastic Optical Networks to Support High-Speed Ethernet

The need for optical parallelization is driven by the imminent optical capacity crunch, where the spectral efficiency required in the coming decades will be beyond the Shannon limit. To this end, the emerging high-speed Ethernet services at 100 Gbps, have already standardized options to utilize parallel optics to parallelize interfaces referred to as Multi-lane Distribution (MLD). OFDM-based optical network is a promising transmission option towards the goal of Ethernet parallelization. It can allocate optical resource tailored for a variety of bandwidth requirements and that in a fundamentally parallel fashion with each sub-carrier utilizing a frequency slot at a lower rate than if serial transmission was used. In this paper, we propose a novel parallel transmission framework designed for elastic (OFDM-based) optical networks to support high-speed Ethernet services, in-line with IEEE and ITU-T standards. We formulate an ILP optimization model based on integer linear programming, with consideration of various constraints, including spectrum fragmentation, differential delay and guard-band constraints. We also propose a heuristic algorithm which can be applied when the optimization model becomes intractable. The numerical results show the effectiveness and high suitability of elastic optical networks to support parallel transmission in high-speed Ethernet. To the best of our knowledge, this is the first attempt to investigate the parallel transmission in elastic optical networks to support standardized high-speed Ethernet.

Airport Slot Allocation: Quo Vadis, EU?

Recently, the European Union (EU) conducted a public consultation on a possible revision of Council Regulation European Economic Community (EEC) 95/93 on common rules for the allocation of slots at Community airports. While open skies agreements are developing rapidly and the Single European Sky (SES) takes shape, airport slot allocation in the EU is based on a regulation that remained nearly unchanged for the last twenty years. The EU could, however, profit from the variety of experiences made in the United States, where secondary slot trading was introduced as early as 1985. Since 2008, slot auctions have moved back into the US spotlight, when the Bush Administration proposed new Congestion Management Rules. Facing a possible capacity crunch in Europe, the question arises: Quo vadis, EU? This article was drafted as a contribution to the 2011 International Air Transport Association (IATA) Legal Writing Award, which was generously sponsored by Jones Day. There is nothing like competition as a goad to efficiency. - Alfred Kahn

Filling the Light Pipe

As data transmission rates continue to increase, optoelectronic engineers are developing techniques to deal with the approaching “capacity crunch.”

The next challenge for cellular networks: backhaul

Growth in the number of mobile users, coupled with the strong uptake of wireless broadband services, is driving high transport capacity requirements among cellular networks. However, revenues are not scaling linearly with increases in traffic. Demand for optimizing the cost efficiency of backhaul is becoming as critical as investment in the radio infrastructure. As a result, new transmission technologies, topologies, and network architectures are emerging in an attempt to ease the backhaul cost and capacity crunch.

Trends in capacity utilization for therapeutic monoclonal antibody production

The administration of high doses of therapeutic antibodies requires large-scale, efficient, cost effective manufacturing processes. An understanding of how the industry is using its available production capacity is important for production planning, and facility expansion analysis. Inaccurate production planning for therapeutic antibodies can have serious financial ramifications. In the recent 5th Annual Report and Survey of Biopharmaceutical Manufacturing Capacity and Production, 434 qualified respondents from 39 countries were asked to indicate, among other manufacturing issues, their current trends and future predictions with respect to the production capacity utilization of monoclonal antibodies in mammalian cell culture systems. While overall production of monoclonals has expanded dramatically since 2003, the average capacity utilization for mammalian cell culture systems, has decreased each year since 2003. Biomanufacturers aggressively attempt to avoid unanticipated high production demands that can create a capacity crunch. We summarize trends associated with capacity utilization and capacity constraints which indicate that biopharmaceutical manufacturers are doing a better job planning for capacity. The results have been a smoothing of capacity use shifts and an improved ability to forecast capacity and outsourcing needs. Despite these data, today, the instability and financial constraints caused by the current global economic crisis are likely to create unforeseen shifts in our capacity utilization and capacity expansion trends. These shifts will need to be measured in subsequent studies.

Data centres off the rack?

Rack space is still scarce in London's data centres, but indications are that an end to the capacity crunch is in sight. Despite growing deployment of blade servers and virtualisation, the demands on UK data centres continue to escalate. New data centre build-outs in the Greater London area have been further inhibited by legislative requirements, designed to ensure that new data centres meet specific environmental requirements before planning applications are approved. The migration of power-hungry applications to the outlying areas will then free up space in central London data centres and erode the business case for building more facilities in London. This approach would mean that significant amounts of floor space would be freed up.

The European Commission’s Airport Package

Congestion is the main problem in European aviation today. Whereas plenty of regulatory and financial effort has been devoted to airspace congestion, the capacity crunch at airports has only recently taken its rightful place in the regulatory spotlights. The European Commission’s Airport Package is the most recent example of European aviation regulation’s continuously expanding scope. This article discusses all three parts of the Airport Package: the Communication on airport capacity, efficiency and safety in Europe, the proposal for a Directive on airport charges and the report on the implementation of the Ground Handling Directive. Since the Package for a large part announces future regulation, the current state of affairs in the regulatory proceedings is included in this overview.

The Capability–Capacity Crunch: NATO's New Capacities for Intervention

In September 2006 NATO's role in Afghanistan expanded to cover the whole of the country. With 32,000 troops under NATO command Stage 4 of the International Security Assistance Force (ISAF) represents an open-ended commitment to rebuilding a country long torn by war and instability. The Alliance's showpiece for advanced military transformation, the the NATO Response Force (NRF) represents a down payment on the future of transatlantic military co-operation. Taken together these two developments reflect the reality of NATO's new interventionism of an Alliance that bears little or no resemblance to that which won the Cold War. NATO today is an organisation designed for global reach and global effect, undertaking operations at their most robust. Unfortunately, the re-design of NATO's architecture has not been matched by a parallel development in Alliance military capabilities. NATO's big three, the US, Britain and France, have taken steps to improve their military capabilities. However, the transformation of NATO's other militaries has proved slow and uneven, leaving many members unable to fulfil any meaningful role. Thus, as NATO today plans for both robust advanced expeditionary warfare and stabilisation and reconstruction vital to mission success in complex crisis management environments a gap is emerging. Indeed, in an Alliance in which only the Americans can afford both military capability and capacity most NATO Europeans face a capability–capacity crunch, forced to make a choice between small, lethal and expensive professional military forces or larger, cheaper more ponderous stabilisation and reconstruction forces. This article explores the consequences of the crunch and the implications for NATO's current and future role as the Alliance struggles to find a balance between fighting power and staying power.

The next cyclic hot spot looms

Regional fab capacity usage rates are closing in on 90%, and the chip industry’s reluctance to add capacity means a capacity crunch is imminent, warns VLSI Research Inc, the San Jose-based market research company predicted that most areas of the world reached 90% capacity utilisation rates or higher in September. Visit www.three-fives.com for the latest advanced semiconductor industry news

Borates: Capacity crunch time

The borates industry has had a tough couple of years. Economic malaise has lowered demand and prices, while substitution has eaten into detergents' market share. Yet major capacity expansions due in the next twelve monthslook set to be its toughest test yet.

So far so good: experiences and challenges in the Scandinavian power market

The Californian power market crisis in 2001 and power blackouts in New York and Italy in 2003 have questioned the robustness of market-based power systems. Electricity reforms in Scandinavia have so far been a success story, and represent the only truly international power market. This article explores the experience and the future of the Scandinavian electricity market, using a scenario analysis to explore what is required to extend the present success story. It is evident that the Scandinavian market will require new investments if a price and supply crisis is to be avoided. Low prices, security of supply, and environmental concerns will remain key energy policy aims, but the coming capacity crunch is likely to rise to the top of the agenda and increase the risk of heavy handed political intervention. Power sector regulation is getting ever more complex and consumes increasing resources, and the scope of regulation is growing. The process of restructuring is likely to reduce the number of actors in all parts of the supply chain, and the dominant role of public ownership may be undermined as the region increasingly integrates into continental Europe.

Polyester bottle resins may face capacity crunch

Polyester bottle resins may face capacity crunch