WARP-5 · Coherent Broadband Networks Embedding Smart Photonics for Cost-Effective Quintuple-Play

Coherent Broadband Networks Embedding Smart Photonics for Cost-Effective Quintuple-Play

WARP-5 (www.warp5.eu) aims at coherent optical broadband networks and introduces novel photonic technology for the extension of capacity and reach thereof. Broadband networks are an important field of research in view of an emerging 5G wireline/wireless infrastructure. Copper-based broadband access based on DSL technologies is a good example for high-throughput data transmission over a narrow communication channel, namely the telephone wire. Here, one uses a sophisticated data modulation scheme to transmit bit rates of more than 10 Mb/s over a spectrally narrow channel with a bandwidth of around 3-4 kHz. Translating these figures to a traffic road, it would correspond to a situation in which 10 cars are driving in parallel on a highway as narrow as 1 cm. In photonics research, one takes another leap and aims at data rates of more than 1 Gb/s when referring to broadband access. WARP-5 investigates how to migrate from nowadays rather slow DSL data rates of about 10 Mb/s towards a sustainable bandwidth of up to 10 Gb/s. This 1000-fold improvement will enable the deployment of novel services, including telephony, internet, 3D high definition video-on-demand, mobile broadband services and services related to smart houses such as remote control or tele-medicine, in a trusted and secure network infrastructure. Broadband penetration is especially important in rural areas that still lag behind when it comes to a modern ICT infrastructure. By bridging this “digital divide” between urban and rural territories, even the outermost areas are stimulated by providing new business opportunities and novel services for the inhabitants. Why photonics? ...simply because photonics provide a better performance than electronics. It is possible to transmit ~10.000-times more data over a single optical fibre compared to an electrical cable. At the moment, one can transmit more than 100 Tb/s over a single fibre as thin as a human hair. At the same time, optics enables the operation of networks over much longer distances, e.g. more than 10.000 kilometres, and with much higher energy efficiency. In order to reach these objectives, WARP-5 applies the concept of coherent optical communications. WARP-5’s scientific mission is... - to break the Tb/s barrier of PON capacities WARP-5 introduces advanced modulation formats in order to leverage the per-user throughput and the capacity of passive optical networks. It does so by generating higher-order modulation formats using low-cost, non-interferometric transmitters based on semiconductor optical amplifiers and electro-absorption modulators. Flexible-format generation at 1 Gbaud was been demonstrated for spectral efficiencies of up to 4 bits/symbol. This corresponds to a 12.8-fold per-user bandwidth increase with respect to the best commercial PON standard. The potential of the low-cost transmitter to operate at higher symbol rates such as 2.5 Gbaud has been validated, which allows for 10 Gb/s per-user connectivity in a 10 Tb/s metro-access PON. A high spectral occupancy is guaranteed through analogue Nyquist filtering and analogue signal recovery for coherent intradyne detection. These techniques contribute to an optical network unit that is not depending on high-bandwidth components or energy-hungry digital signal processing. Finally, WARP-5 integrates quantum communication into classic broadband access networks. It does so by exploiting a quantum-inspired coherent receiver with exceptional sensitivity. - to extend current network loss budgets by one order-of-magnitude At the same time WARP-5 extends compatible network loss budgets to accommodate a massive per-network user density beyond 1000. Electrically-powered field equipment is avoided: Instead WARP-5 exploits infrastructure-defined self-amplification to boost the loss budget by ~12 dB for a fully-loaded coherent access network. Even for low user subscription ratios of 50% a 40-km reach, 1:3072 split network has been demonstrated. Optional Raman amplification for ultra-dense wavelength division multiplexing has indicated another 3 dB improvement in upstream loss budget even in case of a shared Raman pump. With these WARP-5 has paved the way for a compatible loss budget of 60.5 dB at 1 Gb/s guaranteed per-user data rate. This enables a better share of common network infrastructure and reduces capital and operational expenditures. - to unleash physical-layer networking functionality for flexible and scalable metro-access architectures Coherent metro-access networks are following a broadcast-and-select methodology where all the information is sent to every user. The high number of data channels, which can reach beyond 1000, renders such a scheme highly inefficient. It is therefore required to move to a novel network architecture that is more flexible and scalable – especially in view of a highly dynamic 5G infrastructure. To do so WARP-5 has brought, for the first time, a novel class of fully-passive yet reconfigurable network nodes. These reconfigurable network nodes rely on energy scavenging at the physical optical layer, operate at low optical feeds of -10 dBm and provide the functionality of protection switching, load balancing through dynamic spectral and spatial resource assignment. Fast 10 ms switching time in interaction with a control plane and recharge times in the 10 seconds range have been demonstrated. Moreover, ROADM and spectrally coarse wavelength monitoring functionality has been introduced for these passive nodes. WARP-5’s findings allow to migrate from optical networks based on “dumb pipes” to a much more flexible and agile PON. Context-conscious networking can be supported and precious network-resources such as the available spectrum can be used more efficiently. Finally, WARP-5 has re-integrated its principal investigator, Dr. Bernhard Schrenk, at the European level. He has been able to establish his own research group as independent researcher at AIT, the Austrian Institute of Technology in Vienna, while gaining visibility and recognition at an international level through WARP-5’s numerous scientific findings.

Data: CORDIS, © European Union