In general, the Internet transport protocol (namely TCP, the Transport Control Protocol) exhibits suboptimal performance due to the following satellite characteristics: long feedback loops, large bandwidth*delay product, asymmetric capacity. One solution is implementing a TCP PEP. This usually consists in splitting the connection in order to apply more adequate flow and congestion control techniques over the satellite link.
In addition to TCP PEPs, there are other complementary solutions such as application layer PEPs, which implement techniques such as data and header compression algorithms; HTTP acceleration (with caching and web page objects prefetching) and DNS caching techniques. All these PEP techniques are now more and more widespread in satellite communications and were discussed at the workshop.
Delegates from ETSI, ESA and industry took part in lively discussions on current and future standardisation issues such as:
• Capacity management/Quality of Service interface between PEPs, satellite terminals and gateways, including cross-layer techniques.
• Management aspects of PEPs (standard Management Information Bases), configuration and monitoring.
• Multicast PEPs including multicast optimisation and replication.
• Separation of A-PEP (application) and T-PEP (transport) with standard interface.
• Future On-Board Processing satellites with PEPs.
Two presentations from the satellite research community focused on cross layer design, integrated PEPs and Delay Tolerant Networks (DTN) on satellites, while ESA provided presentations on two Advanced Research in Telecommunications Systems (ARTES) projects related to PEPs; TOP and SaNTA. A presentation of ETSI BSM activity on PEP interworking within the BSM architecture was given and two PEP manufacturers, XipLink and Spacebel, shared their experiences and presented their products. These presentations, together with some scientific papers and product datasheets are available for download by clicking on the presentation link in the right column of this page.
Concluding the workshop, Rupert Goodings,the BSM working group chairman, commented: "This workshop has demonstrated a high level of interest in new developments of PEP technology for satellites and I think it is clear that PEPs are an increasingly important feature in satellite systems. Within ETSI we plan to use the outcome of this workshop to initiate further work to identify where standards can assist the deployment of PEPs while encouraging and supporting the range of innovative ideas and products that have been presented."
ETSI is an independent, non-profit, standardization organization in the telecommunications industry (equipment makers and network operators) in Europe. For more information, follow the links located in the right column of this page.
