European Space Agency

Transport Layer Optimization for Dynamic Bandwidth Satellite Networks


The aim of this project is to implement the next-generation gateway, optimized for broadband multi-media communications over satellites. It will draw on the full power of the DVB-RCS protocol, and will merge technical advances on transport layer optimization, Quality of Service (QoS) provisioning and dynamic bandwidth allocation. It will represent a significant advance in TCP/IP acceleration utilizing the Space Communications Protocol Specification - Transport Protocol (SCPS-TP) standard, targeted at dynamic bandwidth systems; providing both more effective network utilization and enhance the user experience to a level that makes full use of the broad bandwidth available.


The key issues addressed in this project are to adapt XipLink SCPS-TP Gateways for optimum bandwidth use within the unique and challenging communications environment presented by DVB-RCS satellite networks.


The technology development will represent a significant advance on the current state of the art for TCP/IP acceleration in DVB-RCS networks: allowing broadband access to be fully maximized.


Dynamic bandwidth systems allow efficient use of satellite bandwidth by allocating bandwidth only to terminals that require it. Current state of the art in TCP acceleration via performance enhancing proxies, such as currently available XipLink Gateways, is limited to two basic approaches. One approach capable of making full use of the available bandwidth is premised on knowing the available link bandwidth, an inappropriate means given the variability and scalability offered by the DVB-RCS infrastructure. The second approach is dynamically estimating available bandwidth through conventional techniques rendered less effective by DVB-RCS network resource allocation methods. In systems where remote terminals are allocated bandwidth dynamically on the basis of service classes and network utilization, the same enhancing paradigms does not fully maximize the performance and bandwidth utilization offered by such systems.

The development will build on its successful implementation of the Space Communication Protocol Specification - Transport Protocol (SCPS-TP) - known commercially as XipLink with vastly improved adaptation for DVB-RCS environments. Working with TCP-to-SCPS-TP protocol gateways, the required flexibility is allowed to shape the network traffic to match as closely as possible the available network bandwidth, with consideration to working with underlying Quality of Service (QoS) mechanisms.


Techniques to improve the performance will be designed, simulated by the Communications Research Centre (using a simulation previously correlated with the XipLink implementation), and finally implemented within XipLink Gateways and tested. Interested parties are encouraged to contact us if they would like to participate in testing.

Current status

The project has been completed successfully in the first quarter 2004. As an integrated component of XipLink, the technology is currently being successfully deployed commercially worldwide, licensed into DVB-RCS terminals and sold as standalone XipLink Gateways. Further information is available at

Status date

Thursday, June 28, 2012 - 11:35