 
Summary: A Linear Time ErasureResilient Code
With Nearly Optimal Recovery
Noga Alon
Michael Luby
Abstract
We develop an efficient scheme that produces an encoding of a
given message such that the message can be decoded from any por
tion of the encoding that is approximately equal to the length of the
message. More precisely, an (n, c, , r)erasureresilient code consists
of an encoding algorithm and a decoding algorithm with the following
properties. The encoding algorithm produces a set of bit packets of
total length cn from an nbit message. The decoding algorithm is able
to recover the message from any set of packets whose total length is
r, i.e., from any set of r/ packets. We describe erasureresilient codes
where both the encoding and decoding algorithms run in linear time
and where r is only slightly larger than n.
1 Introduction
Most existing and proposed networks are packet based, where a packet is
fixed length indivisible unit of information that either arrives intact upon
transmission or is completely lost. This model accurately reflects properties
