3 ms·
> A combination approach could allow a tradeoff between using double or triple the raw bandwidth You can control the overhead while increasing recovery rate o
by AYBABTME 6y ago
> A combination approach could allow a tradeoff between using double or triple the raw bandwidth
You can control the overhead while increasing recovery rate over multiple paths fairly well, with non-integer overhead (>1x but <2x, etc) with erasure coding techniques. Some erasure codes can allow you to control that overhead (code rate) precisely, but have legal imbroglios: https://en.m.wikipedia.org/wiki/Fountain_code https://en.m.wikipedia.org/wiki/Fountain_code
- benlivengood 6y agoI am curious about the overhead on a packet network for erasure codes. I am guessing they're easier to use on a channel oriented network where a small number of senders and receivers are protecting a multiplexed packet stream. Additionally I'm guessing the most effective use would be 2D encodings like optical media use to spread the codes out over time (for runs of bit errors) and space (single bit errors) which would introduce another latency/efficiency tradeoff.
- londons_explore 6y agoIf you have bursty bit errors on a link, erasure codes can correct them without a round trip while not adding latency in the case where a burst of errors didn't occur. Having said that, I don't think this situation will apply to spacex. They probably won't get random bursts of errors. Noise levels will be very deterministic and can be calculated ahead of time by looking at what stars are "behind" the satellite.