Transparent Internet Protocol Communication Over X-Band/S-Band Links for High-Altitude Platforms

Abstract

This paper outlines a hybrid X-band/S-band payload communication setup for high-altitude platforms, which is transparently exposed to the user as a full duplex asymmetric Internet Protocol (IP) link. Unification of the high-capacity Xband downstream channel and low-capacity S-band upstream channel happens with tunnel interfaces on both the air and ground sides. High packet acknowledgment rates that occur when the reliable Transmission Control Protocol (TCP) is run directly over the tunnel get reduced through a translation into the QUIC protocol and vice versa with software protocol bridges installed at each endpoint. As a side effect, key features of QUIC such as its low handshake overhead and Transport Layer Security (TLS) encryption are inherited. Transmission tests with a motor glider aircraft carrying a simulated Earth observation payload using TCP exhibited peak data rates close to the theoretical limit of around 97 Mbps for the X-band downlink and acknowledgment traffic well below 100 kbps for the S-band uplink.