- Use a more efficient satellite technology permitting the use of the Adaptive Coding and Modulation (ACM) in both the forward link and the return link for a better space segment efficiency
- Improve reacquisition time of the satellite system (modem) after long shadow zones
- Develop a more robust TCP and HTTP acceleration system to be able to handle satellite link with high end-to-end delays adapted to cope with the type of traffic used by the train users
- Better QoS implementation in order to discriminate different typologies of traffic;
- Aggregate links of different nature (e.g. terrestrial and satellite) with different end-to-end delays in order to make them acting as one aggregated link
- Making ACM work in both Forward and Return link in a mobile environment with frequent obstacles
- Cellular and satellite link are different, it will be a challenge to make them work together with generic components sourced from third parties
- Organising a pilot on a commercial train.
The main benefits for 21Net and its customers would be:
- increasing the availability of the “Internet on board” service
- improving the final user experience
- minimizing the cost per bit ratio
The 21Net system architecture relies on two-way Ku-band satellite transmission to provide connectivity between the internet backbone and the train. The satellite operator selected for the project is Hispasat.
- The Access Control Gateway (ACG), which contains the Authentication, Authorization en Accounting (AAA) and the on board portal
- The Mobile Access Router (MAR), dedicated to route traffic to the satellite or to the terrestrial link
- The Accelerator (ACC), to optimise the TCP connection efficiency even with high latency link
- The Satellite modem (SAT) used for the Satellite connections
- The Cellular Modem (Cell) used to connect to multiple cellular network providers
- ACC: Improvement of the efficiency of the “acceleration system”
- MAR: Bonding of the link using different access technologies (cellular, satellite, WiFi)
- SAT: By the adoption of a new modem (iDirect) we expect to succeed in using ACM technology in both the forward and the return link at an improved cost/bit ration; during the project the link control will be customised for the train environment
- Filtering system: Application consuming high bandwidth will be filtered to avoid congestions
The project is divided in three main stages:
- First stage: development and static test in the lab
- Second stage: testing in mobile environment complemented with development and test in lab
- Third stage: going live for a Pilot of 1 month on a commercial train
All the main activities are conducted by 21Net.
The CDR meeting has been successfully carried out in June 2014, which marked the completion of trade-off and design activities.
Acceptance tests of the system are expected to take place in July 2014.