TETRYS: Improving video transmission over DTN, WiFi or mobile networks

Ref-Nr: TDO0156

Technology abstract

TETRYS is a new reliability protocol designed for IP networks where retransmission is either problematic or not possible, such as Delay Tolerant Networks (DTN), WiFi or 3G/4G mobile networks. For example Tetrys can boost video delivery over a WiFi network by up to 400% when radio conditions are not optimal, which is often the case. 


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Technology Description

Developed by the French aerospace engineering school ISAE and based on a new "on-the-fly encoding" approach, TETRYS offers a novel reliability mechanism with an implicit acknowledgment strategy that could be used in DTN or any lossy network for multimedia traffic, in the context of unicast or multicast transport IP protocols.

Tetrys is both a FEC coding scheme (e.g. it relies heavily on random linear FEC codes) and a transport protocol (it defines packet formats and protocol rules). Only the client and server sides need to implement Tetrys. As such it can be applied in several different places in a protocol stack:

  • Below an application generating RTP packets for real-time video content, because of Tetrys? exceptional benefits in terms of timely delivery of contents;
  • Below TCP where it can help recover from losses in wireless channels. Here poor reception conditions heavily hinder TCP connections since TCP assumes losses are caused by congestion and backs off, which is of no benefit in case of bad signal/noise issues;
  • In Delay Tolerant Network (DTN) systems, where feedback is not necessarily timely, nor necessarily feasible. In that case Tetrys offers a robust delivery even in presence of poor packet and feedback transmissions

Innovations & Advantages

TETRYS enables a fully or partially reliable delivery of contents, potentially with real-time constraints, better and faster than the TCP protocol or traditional block FEC solutions would enable.

  • It can boost video delivery on lossy networks such as WiFi or mobile networks by up to 400%.
  • It can reduce the average decoding delay in the case of several receivers.
  • It supports unicast or multicast applications.

Current and Potential Domains of Application

Wifi and 3GPP Networks that are exposed to strong data losses which impact real-time services:

  • Live streaming Video / Broadcast
  • Video-conference
  • VoIP and files transfer
  • Defense communications
  • Space and Delay Tolerant Network (DTN)