Satellite links are characterized by long round trip times (RTTs) and harsh channel conditions that are sensitive to atmospheric conditions such as rain fade, fog, sun outages, and attenuations.
Geostationary satellite links, for instance, have typical round trip latencies of 1,000-1,400ms, two orders of magnitude higher than typical RTTs seen by high-speed internet users. While packet losses depend on physical channel coding, packet and frame dimensioning, and flow rates, satellite link loss rates can reach 50% in extreme conditions.
Current solutions to counter the high and bursty packet losses are based on implementing multiple layers of redundancy. The resulting bandwidth inefficiencies can be significant, particularly in conditions where spectrum is very expensive. Furthermore, conventional forward error correction methods cannot adjust to changing loss patterns.
Our technology offers new link implementations that optimize bandwidth usage by removing unnecessary redundancy. It is particularly effective in dynamic satellite conditions with fluctuating signal levels.
In particular, our coding approach is unique in that it enables the straight-forward implementation and management of sliding-window coding techniques. Such techniques are capable not only of adjusting to losses in real time, but also of integrating into ubiquitous transport protocols such as TCP.
In addition to its solid performance gains [link: Coded TCP use case] in conventional networks, Coded TCP (CTCP) has shown excellent results in high-RTT satellite emulation experiments. It consistently surpasses conventional TCP implementations within a wide range of loss levels. At high loss levels (20%), CTCP realizes has demonstrated a throughput level that is 20x the throughput of its closest commercial TCP competitor.
Our partners at Speedy Packets offer TCP products for satellite links.