New optical fibres for high-capacity optical communications
Professor David Richardson FREng, University of Southampton, UK
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.
The benefits of convergence
Professor Gee-Kung Chang, Georgia Institute of Technology, USA
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.
Maximising the optical network capacity
Professor Polina Bayvel FREng, University College London, UK
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.
Physical limitations to network capacity
Dr René Essiambre, Alcatel-Lucent, USA
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.