HydRON: High thRoughput Optical Network

Abstract

Optical communication technologies offer unprecedented transmission data rates, resilience and data security to satellite communications. ESA and its member states have successfully introduced optical communication technologies in the European Data Relay System (EDRS), providing commercial Quasi-Real-Time-Data service to the European Commission Copernicus satellite fleet (Sentinel-1A/B, Sentinels-2A/B). The EDRS / SpaceDataHighway has already provided more than 25.000 successful links since start of operations in 2016, resulting in an availability of >99.5%, [1], [2]. Nonetheless, full capabilities of optical technologies cannot be fully exploited, because these optical are mainly used in non-optimized SatCom systems. In response, a dedicated programme for Optical Communication Technologies was created in 2016 by ESA called ScyLight (SeCure and Laser communication Technology). Furthermore, to address the system level aspects for the massive introduction of optical / photonic technologies in SatCom systems, ESA has recently launched several internal and external initiatives in preparation of an innovative project proposal called HydRON (High Throughput Optical Network), [3]. In HydRON, optical interconnections in the Tbps regime (Terabit per second) are envisaged including All-Optical payloads furnishing the bridges for a truly Fibre in Space network, as shown in Figure 5. Technically speaking HydRON aims at Tbps All-Optical Network solutions, dividing the satellite payload into (i) a network part and (ii) an application / service part, equivalent to the backbone part and the access part of optical fibre networks on ground. The application / service part (i.e., the RF payload) has access to the network part (i.e., the HydRON elements), in a similar way as computers are connected to the terrestrial network. HydRON will prepare optical feeder links into a network of in-orbit Technology Demonstrators (called HydRON#1, #2, etc.), which will be interconnected by means of Tbps laser intersatellite links. WDM (W avelength Division Multiplexing) laser communication terminals (on ground and in space), and optical switching / routing capabilities on-board the network nodes in space will be implemented together with optical to enable a high throughput network connection to the application / service part (i.e., the RF payload). The space network concept will reduce the dependency on single ground stations as all HydRON nodes will get their particular data via the network they are interfacing with. A combination of new optical technologies, novel photonics equipment and efficient network concepts will be proven in orbit. However, the overall network architecture must be optimized for satellite networks. This architecture must be satellite-technology specific and adaptable to the changing network conditions. The ultimate goal is to seamlessly integrate the space optical transport network into the terrestrial high capacity network infrastructure: the Fibre in the Sky.