Impact of Delayed Acknowledgments on Transport Layer Performance over Low Orbit Constellations

Bastien Tauran (1) , Emmanuel Lochin (1) , Jérôme Lacan (1) , Fabrice Arnal (2) , Mathieu Gineste (2) , Nicolas Kuhn (3)

1 ISAE-SUPAERO - Institut Supérieur de l'Aéronautique et de l'Espace
2 TAS - Thales Alenia Space [Toulouse]
3 CNES - Centre National d'Études Spatiales [Toulouse]

Satellite transmissions can suffer from high channel impairments, especially on the link between a satellite and a mobile end user. To cope with these errors, physical and link-layer reliability schemes have been introduced at the price of an increased end-to-end delay seen by the transport layer [for example, Transmission Control Protocol (TCP)]. By default, the TCP enables delayed acknowledgment (DelAck) that might increase the end-to-end delay when performing over satellite link-layer recovery schemes. As a matter of fact, even if this option enables decreasing the feedback path load and the stack processing overhead, it might be counterproductive in a satellite context. This motivates the present paper, which aims to quantify the impact of such a TCP option in the context of low Earth orbit satellite constellations. Several simulation measurements are performed with two well-deployed TCP variants, and it is shown that DelAck should be disabled when used over link-layer Hybrid Automatic Repeat Request schemes, particularly when these schemes enable reordering the buffer.

Domaines: Réseaux et télécommunications [cs.NI]

Bastien Tauran, Emmanuel Lochin, Jérôme Lacan, Fabrice Arnal, Mathieu Gineste, et al.. Impact of Delayed Acknowledgments on Transport Layer Performance over Low Orbit Constellations. Journal of Spacecraft and Rockets, 2019, 56 (3), pp.630-635. ⟨10.2514/1.A34190⟩. ⟨hal-02535694⟩