5 ms·
Reed-Solomon coding is an old fella. Whenever you have a link which is unreliable and you can't afford to retransmit packets on the link when errors are introdu
by jlouis 18y ago
Reed-Solomon coding is an old fella. Whenever you have a link which is unreliable and you can't afford to retransmit packets on the link when errors are introduced, RS is your friend. Mobile phones are among the prime users of this.
If I remember correctly, the PAR/PAR2 formats used on usenet is using RS-encoding as well.
An alternative would be to plot the file in N-dimensional space and define a set of vectors to pinpoint it. When you have enough vectors you have the precise pinpoint. Additional vectors gives the error-correction capability. Some microsoft guys played with this idea for Bittorrent-like networks a while back. But there is a disadvantage in the time it takes to decode the data, and it probably doesn't help the swarm that much :/
Another interesting viewpoint: We might need RS-encoding on the local harddisks soon (implemented in hardware or software), as it would circument the bit-error rate problem with those disks.
- newt0311 18y agoWhat I am wondering about is how much faster TCP could be with RS for recovery instead of the current resend-packet technique.
- jws 18y agoI would guess it would be slower and you would break the internet. You would have to introduce enough redundancy to cope with the worst tolerable loss rate which would increase the number of bits to transmit. Worse, it is the noticing of dropped packets that tells TCP to slow down and decongest a link. If enough senders fail to decongest then packet loss on the congested links skyrockets wasting bandwidth elsewhere and doing silly things like favoring the sender with the biggest pipe.
- wmf 18y agoObviously you can't just eliminate congestion control, and the coding rate should be adaptive to reduce overhead. At least one startup has gone broke on this idea already, but maybe it's possible to do it right.
- whalliburton 18y agohttp://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_correction http://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_corr...
- wmf 18y agoHard disks already use error correction, but you can add more if the uncorrectable error rate isn't low enough for you.