After decades of research and expectations, Fibre-to-the-Home is becoming a reality in our cities, streets, homes. Real commercial products and real deployments of optical fibre access are taking place, usually in xPON tree topology. The most used communication protocol is GPON, at 2.5/1.25 Gbit/s in down/up-stream, to 32 or 64 users; as a consequence, once the fibre is arriving to our home, it can be somehow disappointing that we can only enjoy about 40 MBit/s guarantied, when we know that fibre can transport Tbit/s.
Therefore, the time is now for IT researchers to assure that this our optical channel available is used advantageously, without limitations, in terms of bidirectional capacity, length, user density, quality of service, etc, towards what is being defined as the Next-Generation PON. The new enabling technologies and control methods, that are explored to build over the currently deployed optical infrastructure, will be discussed at the ACCORDANCE Workshop on Broadband Access at ICTON'2012, like:
- PON modulation formats, like OFDM, SCM, coherent, etc
- advantageous intensive use of the WDM domain,
- all-optical amplification and routing,
- dynamic optical bandwidth allocation algorithms
- multi-operator open access networks
- wireless-wired convergence
To find out more about the event, visit the ICTON 2012 website.
ACCESS-ACCORDANCE invited presentations:
What's left in fiber access bandwidth?
A.L.J. Teixeira, University of Aveiro, Portugal
We will, in this paper analyse, the different impacts of the stacking of different legacy technologies and the tolerances required along the years in the available windows for NGPONx. Considerations will be made in terms of fiber limitations, technology requirements and cost position.
Multi-carrier transmitter for future access networks
Tam Huynh, Rui Zhou, S. Latkowski, F. Smyth, Li. Barry, P. Anandarajah, The RINCE Institute, Dublin City University, Ireland
The explosive growth of the internet, fuelled by the ever-increasing information processing and data creation capability placed at the consumer's disposal, has triggered the introduction of fibre based broadband access networks such as Fibre To The x (FTTx) technology to replace copper based last mile networks. To date, these FTTx networks, have been based on Time Division Multiplexing (TDM) and use dynamic bandwidth allocation algorithms to distribute available capacity amongst users. However, traffic patterns that were once heavily asymmetrical in favour of downloads from network to user are now exhibiting more balance between upstream and downstream bandwidth, as user uploads and peer-to-peer transfers increase. In light of these changes and the requirements imposed by the evolving networks (aggregated bandwidth & allowable power budget), TDM based access networks may struggle to cope. Hence, Next Generation Access Networks (NGANs) may employ Wavelength Division Multiplexed Passive Optical Network (WDM-PON) technologies that are capable of offering features such as enormous bandwidth, large split ratio, extended transmission reach and enhanced security. Additionally, WDM-PON technology can be combined with advanced modulation formats to increase the information spectral density, thereby improving the overall efficiency of the network. However, there are significant obstacles to the widespread deployment of WDM PONs, such as the high cost and energy consumption of current Optical Line Terminal (OLT) transmitters and Optical Network Unit (ONU) receivers. In this work, we present a multi-carrier transmitter based on a gain switched laser employed in a NGAN. This simple, robust and cost efficient direct modulation based comb generation technique offers closely spaced coherent channels. The authors also present a performance comparison between the commonly used coherent detection scheme and a novel receiver architecture based on a pilot tone aided direct detection scheme. The simplified low cost receiver, enabled by the phase correlated optical comb tones, eases the requirement for an expensive local oscillator (tunable laser), reduces the need for digital signal processing and also greatly enhances the phase noise tolerance of the system.
Technologies for next generation optical access
E. Weis, D. Breuer, Deutsche Telekom AG Laboratories, Berlin, Germany
Based on operator requirements next generation optical access (NGOA) technology and architecture concepts will be technically and economically assessed. Furthermore network migration aspects starting from today's GPON deployments towards NGOA architectures will be presented.
Linearization techniques of electro-optical converters for multi-format OFDM-based PONs
A. Cartaxo, F. Carvalho, T. Alves, J. Morgado, Instituto Superior Técnico, Lisbon, Portugal
Techniques of linearization of electro-optical converters are reviewed, and their performance is assessed numerically and experimentally for multi-octave multi-format orthogonal frequency division multiplexing -based signals used in passive optical networks supporting quadruple play services.
Wavelength switched hybrid WDM/TDM PON: A flexible next-generation optical access solution
A. Dixit, B. Lannoo, D. Colle, M. Pickavet, P. Demeester, Ghent University – IBBT, Belgium
In this paper, we propose the system concepts of a next-generation wavelength switched hybrid wavelength division and time division multiplexing (WDM/TDM) passive optical network (PON) architecture. In this architecture, wavelength selective switches (WSSs) are used at the remote node to improve flexibility, data security and power budget compared to other hybrid WDM/TDM PON variants. We map the proposed architecture to the requirements of next-generation optical access networks in a 2020 perspective. Finally, we benchmark the proposed architecture with other proposed hybrid WDM/TDM PON solutions.
Demonstration and analyses of a hybrid multiplexing scheme for scaling-up the "last mile"
I. Glesk, T. Osadola, S. Idris, K. Sasaki, G.C. Gupta, University of Strathclyde, Glasgow, UK
The need for delivery of the large amount of data has triggered a growing demand for high-speed secure optical networks which need to be capable of supporting very large numbers of simultaneous users and the same time have minimal hardware requirements. However, to achieve this vision in a last mile (access) is still long time away. Access networks purely based on a wavelength-division multiplexing (WDM), optical time-division multiplexing (OTDM) or optical code-division multiplexing (OCDM) scheme, cannot alone satisfy those requirements. Therefore, hybrid solutions incorporating WDM / OTDM have already been proposed and demonstrated. Here each user is assigned a different wavelength and/or its own timeslot for his unique identification. In this paper, to best of our knowledge, we present for the first time a proof of concept field demonstration of a transmission system based on an incoherent OCDM over OTDM (iOCDM-OTDM). Based on our system analyses which also include scalability and power budget calculations, the proposed iOCDM-OTDM architecture can deliver significantly enhanced system scalability and a substantial increase in the number of simultaneous users. The encoding/decoding based on two-dimensional wavelength-hopping time-spreading (2D-WH/TS) codes was done with fiber Bragg grating (FBG) encoders/decoders. In addition, to further improve system performance, a picosecond time gating taking advantage of self-clocking scheme with all-optical clock recovery was introduced for proper synchronization. Obtained results with the detail summary of the system performance will be reported based on conducted field trials.
Analysis on FTTx deployment and technology in Asia-Pacific and perspective through lessons learned
S. Hanatani, Telecommunication & Network Systems Division, Hitachi Ltd., Japan
With a view of that most of FTTx mass-deployment has been in Asia-Pacific region last decade, analysis and lessons on FTTx network architectures, technologies and business models deployed in Asia-Pacific are discussed and perspective on FTTx development next decade is provided.
Green, elastic coherent IFDMA for next-generation access network
Ken-ichi Kitayama, Y. Yopshida, A. Maruta, Osaka University, Japan
K. Ishii, Y. Akiyama, T. Yoshida, N. Suzuki, K. Koguchi, J. Nakagawa, T. Mizuochi, Information Technology R&D Center, Mitsubishi Electric Corp., Kamakura, Japan
R&Ds and standardization activities of Next-Generation (NG) passive optical network (PON) have been underway, which will upgrade existing 10G-PON commercial Fiber-To-The-Home (FTTH) systems. NG-PON2, coming after NG-PON1, will bring a revolutionary change. Among technology candidates of NG-PON2, OFDMA has an attractive capability of "elastic" bandwidth provisioning. However, there remain issues to be solved; one is the high power consumption as high as 100W per optical network units (ONU) due to mainly discrete Fourier transform (DFT) circuits at the transceiver, and the other is the high peak-to-average-power ratio (PAPR), which is susceptible to the fiber nonlinearities. In this talk, our recent R&D activities of coherent interleaved-frequency division multiple access (IFDMA), a special class of OFDMA, for a green, elastic next-generation access network will be presented. We will show a low-power consumption SRAM-based FPGA circuit for the IFDMA signal generation without IFFT circuit. We will also show a carrier synchronization technique between multiple ONUs by using low-complexity carrier frequency offset (CFO) pre-compensation DSP. Finally, we will experimentally demonstrate up to 30Gbps elastic bandwidth allocation to 2 x ONU by using QPSK and 8PSK.
MAC protocol requirements for OFDMA-PONs
Wansu Lim, M. Milosavljevic, P. Kourtessis, J.M. Senior, University of Hertfordshire, UK
This paper provides specifications of the parameters defining the design of medium access control (MAC) protocols for orthogonal frequency division multiple access (OFDMA) passive optical networks (PONs). The requirements of MAC protocol have been developed by the ACCORDANCE topology, extendable in reach, subcarriers and ONUs, the upstream and downstream bitrates and modulation formats. The foreseen functionalities have been attained by the extension of the upcoming XG-PON frame structures.
QoS mapping for LTE backhauling over OFDMA-PONs
Wansu Lim, M. Milosavljevic, P. Kourtessis, J.M. Senior, University of Hertfordshire, UK
This paper reports on the mapping of LTE bearers to optical resources, to satisfy the stringent QoS requirements of both the wireless and optical networks in the converged OFDMA-PON and wireless topology. It is dedicated to the development of QoS mapping mechanisms for enhanced Node B (eNB) backhauling, to ensure minimum delays at the LTE evolved packed core (EPC). Various options for exhibiting QoS mapping between the LTE bearers and optical queues have been presented. These include, wireless classes forwarded directly to one priority optical queue (so called non-mapping mechanism), 1:1 mapping where Class Identifier, QoS channel indicator (QCI), levels are mapped to their respective priority optical queues and finally group mapping. Performance figures, based on system level simulation, are drawn with respect to the QCI delay between eNBs and EPC for various numbers of users per cell.
OFDMA based PONs with reduced hardware requirements through advanced signal processing
C. Ruprecht, W. Rosenkranz, University of Kiel, Germany
Possibilities of reducing hardware requirements and therefore costs in an OFDMA-PON are shown. This is achieved by reducing the complexity of A/D and D/A converters and of the Digital Signal Processing (DSP) involved. The feasibility is shown experimentally as well. Furthermore, by incorporating techniques of the copper based access network, a flexible transmission network with advanced signal processing can be achieved and by applying techniques like bit and power loading, the data rate or the spectral efficiency can be increased. Moreover by assigning only certain subcarriers to various users, the effect of power fading can be mitigated.
Planning and designing FTTH networks: Elements, tools and practical issues
J. Segarra, V. Sales, J. Prat, Universitat Politècnica de Catalunya, Barcelona, Spain
Fiber-To-The Home (FTTH) provides the offered and new broadband services. Now it is deployed massively worldwide with Passive Optical Networks (PONs), being the EPON and GPON standards the most used. In this paper we consider solutions for planning and designing such optical fiber access networks from the point of view of an incumbent operator; taking into account components administration, mapping tools, design applications and automation resources; therefore, managing structures, materials, geography, houses, buildings and users databases. The networks will be dynamic, so the proposed designs and utilities must also be active to reach thousands of passed homes and to cover the life-cycle of the networks and not only the initial built.