# Difference between sticky channel Poisson-repeat channel

I don't quite understand the difference between a sticky channel and Poisson-repeat channel. A sticky channel allows duplications of symbols sent over the channel, then the block structure at the sender and receiver will be the same (Taken from "A Survey of Results for Deletion Channels and Related Synchronization Channels" by Professor Michael Metzenmacher). But I don't understand what is meant by block structure. Is it just referring to the structure the packet, such as the overhead, the payload, etc? A Poisson-repeat channel is defined as: the sender sends a sequence of n bits, and the channel independently replaces each bit with a number of copies (or repeats) that has a discrete Poisson distribution with mean 1. Taken from this blog. But it seems as if the two channels are the same. What exactly is the distinction?

• I don't understand the part of your question about "block structure". Can you provide more infornation or link a source? – MBaz Aug 2 '16 at 21:22
• I have provided the publication from which I derived my definition. Sorry for having not included it before-hand. – Christian Aug 3 '16 at 6:28
• I've updated my answer after taking a quick look at the paper. Note that the block structure it refers to is related to the code words, which are affected differently when there are deletions (in repeat-Poisson) than where deletions are forbidden (in sticky channels). – MBaz Aug 3 '16 at 22:46

The Poisson-repeat channel is a binary channel where each transmitted bit is repeated at the channel output anywhere from $0$ to $\infty$ times. The repetition distribution is Poisson.
A "sticky channel" is a repeat channel where deletions are forbidden; that is, every transmitted bit is repeated from $1$ to $\infty$ times at the channel output, according to some specified distribution.