ozgun.harmanci

2005-04-08 08:16:50 UTC

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Hi everybody, I hope this is right place to as this question.Raw Message

[No. Coding theory and cryptography are very

different subjects. But it's a serious question

and perhaps our contributors can help you anyway.

So I'm letting it through. -- Moderator (ggr)]

I am

trying to implement encoder and decoder for Mckay and Luby's tornado

codes in c/c++, I will use them in a school project based on optimizing

a network traffic for multicast real time data transmission. We assume

that error probability is negligible and loss rate is high. I have

understood basically how tornado codes work however I think there are

not really any programming resource on them. I dont want to write whole

code from scratch by myself based on my simple pathetic understanding,

I thought it will be easier to see some working code and modify it. So

do you know of any programming resources on tornado codes? (or

generally any code about digital fountain codes)

Secondly while building the graph for encoding a source (again for

tornado codes) we have to choose degree distribution based on soliton

distribution and then after assigning degrees to right nodes on graph,

we create (degree) many connections to left nodes randomly. Is that

correct until this point? Is there anything I miss?

Suppose I have created graph and everything, how do you think I should

send encoded data to decoder? I mean in tornado codes there are really

not discrete codewords I mean we can speak of rate of code but it is

based on whole encoding ratio of data, right? I think rate is defined

as:

rate = (encoded data size) / (pure data size)

So how should I segment encoded data to send it to decoder?

Thirdly how do encoder and decoder agree on degree distributions, I

have read that this data is also sent with node packets from encoder

however if that is lost then whole graph will be messed up, right?

thanx in advance.