EODIS network and services are being developed with the aim to disseminate the large amount of EO products coming from the Ground Segments of several Acquisition Stations. This will establish a complete end-to-end data distribution service over a satellite link complemented by a terrestrial network (Internet) used to transfer protocol control messages.
The most exacting load of data to be disseminated is currently represented by the Envisat data which requires regular distribution planning, but the study will aim at the distribution of the so-called 'Third Party Missions' (i.e. non-ESA) data coming from NOAA, LANDSAT satellites, etc, whose data shall be included in the dissemination service.
EODIS will be able to operate on a network consisting of many TXs (two TXs are foreseen in the first operational phase of the project), and RXs (five RXs are foreseen in the first operational phase of the project), managing to transfer simultaneously data files to a set of addressed RXs (multicast) or even to all RXs stations at the same time (broadcast).
EODIS shall be able to manage easily and with priority tasks which have been scheduled as well as 'on demand' session requests coming from a multitude of users spread over Europe.
Reliability and completeness of the data dissemination function are key-factors for the quality of the datacasting implementation. The user feedback for quality control of data and the presence of a separate network operational centre capable of network management and control will allow a constant monitoring of the network performance.
Since the network needs to be competitive in order to offer cost-effective quality services, several optimisation techniques will be performed in order to minimise resource misuse or waste.
The resource optimisation includes several performances:
- Resource reallocation as data becomes obsolete. Since some data have delivery time constraints, the transmission could be useless if data are transmitted over the maximum time allowed. In this way it is appropriate to abort or cancel the scheduled session in order to free resource space for other transmission sessions.
- Bandwidth and time optimisation in order to guarantee the maximum tolerable traffic according to the system features and the highest reliability of data transmission.
- A user-friendly client platform interface will also be provided in order to allow the client to use controls and functionalities he is familiar with.
EODIS provides a dissemination service for Earth Observation products over a commercial satellite channel.
EODIS systems aim at fitting the dissemination requirements of two major entities:
- PDS Dissemination Facility (DF), requesting distribution of ENVISAT products,
- TPM User Services, interested in distribution of Third Party Missions and ERS products.
The EODIS network consists of 3 subsystems at different locations:
- The EODIS Operating Centre (EOC), which is in charge of planning, monitoring and logging all the network activities,
- The Transmitting Stations (TX), where products made available by DF or TPM User Services are routed through the satellite link,
- The Receiving Stations (RX's), where products transferred become available to the users at to the Distribution Entities (DE) that requested them.
The Project is being developed in two phases:
Phase I - (March 2003 - August 2005)
During this phase the EODIS system (Eodis Operation Centre, TX Sites, RX client sites) will be set-up for the Pilot Operations. The phase 1 ends with the Mid Demonstration Review (MDR).
Phase II - (September 2005 - December 2005)
During this phase the EODIS Pilot Operation will be executed and the commercial strategy defined. The Phase ends with the Final Review (FR) where the pilot Operations evaluations results, recommendations gathered from the end user community and the future strategy will be provided.
The deliverables for the Final Review were provided during week 49 (2005). The Final Review was successfully carried out during week 51 (2005).
The EODIS system has been developed as a valid technical solution to efficiently handle the dissemination of large amounts of systematic and on-demand data coming from different transmitting nodes to a large receiving park (hundreds) of users. Demonstrations were carried out on a limited number of stations but the system is easily expandable to match initial specifications. This is mainly achieved through a DVB-S channel for high-rate traffic data via an Internet return link for Monitoring and Control data and through the ALISEO module in charge of managing the allocated resources.
User evaluation has been positive, as they appreciated the high reliability of the system and the detailed and user friendly web interface (installed on each receiving platform). It allowed them to keep the overall status of reception tasks under control. They perceived the high potentiality of the EODIS infrastructure and declared their interest/availability in order to exploit its features for future operational scenarios.
Today, the delivered EODIS system does not yet represent a fully commercial and self-standing packet offering, although its features can be taken as a valid model in order to develop additional service layers. In fact, standard accounting, billing and advanced Monitoring & Control features (as the Web Server on the ALISEO module) at the moment have been not implemented but can be easily adapted and integrated in the developed EODIS platform.