[Sis-csi] Text for Transport Layer Section

[Lloyd Wood]

At Tuesday 2006-04-25 14:57 -0700, Scott Burleigh wrote:
>CFDP is designed to run over a deep-space radio link, where the laws 
>of physics pretty much assure that if bits arrive at all they arrive 
>in the order in which they were transmitted.

Modern coding theory and interleaving to ensure robustness to 
interference (FEC, LDPC, turbo codes, even interleaved concatenated 
codes) pretty much ensures that that claimed in-order delivery of 
bits does not, in fact, actually happen. Ever. While still obeying 
the laws of physics.

How the modem can still present you with an in-order serial stream by 
hiding this encoding and interleaving from you is one of the nice 
things that makes e.g. the HDLC serial stream abstraction possible. 
It's a nice layering outcome.

L.

<http://www.ee.surrey.ac.uk/Personal/L.Wood><L.Wood at surrey.ac.uk>