Subject: Re: IP checksum

From: [email-masked]
Date: Wed, 18 Aug 1999 14:33:16 -0400

>From: Bora Akyol <[email-masked]>
>
>Moreover, on wireless links, since the link quality is constantly
>changing (Fading, etc), it is very difficult to optimize the amount
>of FEC overhead vs data to be sent. On links where the RTT is short,
>ARQ based procedures can be more affective and efficient than FECs.
>[...]

Peter Steenkiste and I have observed a short-RTT link which
experiences error situations in which nearly every packet has
significant errors (we have observed a packet corruption rate of
94% in one situation).  ARQ, unless it includes energy combining,
is not effective in this situation, but simple adaptive FEC is very
useful, allowing an otherwise unusable link to perform acceptably.

http://www.cs.cmu.edu/afs/cs/project/cmcl/archive/Darwin-papers/98monet.ps
is an evaluation of various error control policies, including ARQ,
based on bit-level error traces of NCR WaveLAN.

Dave Eckhardt