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Convolutional codes, Linear block codes

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lifegood

lifegood

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Channel Coding

Hi everyone,

I know that there are a couple of channel coding methods (e.g Convolutional codes, Linear block codes) in coding theory.

I was told that, in general, larger generator matrix (in term of size of n,k) produces better performance.

Can someone please explain this? Many thanks.
 

Re: Channel Coding

C=1/2*log(1+SNR)

Above channel capacity formula was given by Shannon and he told that this capacity is achieved with infinite length random codes.

Therefore to achieve capacity,your code should be as close to infinity as possible and same with its randomness.

All of the coding persons tried to achieve this and LDPC and Turbo are one which are close to Shannon.
 
Re: Channel Coding

Hi,

Can you urwelcome explain in more details . So that we can get your point.

thanks in advance
 

Re: Channel Coding

take a (n,k) binary code. Of the 2^n possible combinations, only 2^k are valid codewords. So bigger the n, the further spread out your codewords can be, in the set of all 2^n possibilities. And the more dissimilar your codewords are, the better your error correction performance will be. So increasing n increases the coding gain (of course, code has to be good). Does this explain?

Downside of course is that your rate goes down very badly. You end up sending more redundnat info that real data.
- b
 
Re: Channel Coding

The essence of channel coding is to introduce redundancy to the information bits, and this is achieved, indeed, by averaging out the uncertainty of the channel (e.g., fading or AWGN). Now it is obvious that to get a better averaging result, we need more lengthy code.

This applies to all kind of channel coding techniques.
 

Re: Channel Coding

HI ...

JUST RY OUT THIS BOOK ... ITS TOO GOOD IN TERMS OF THESE CODINGS AND U WILL GET THE BASICS OF THE CHANNEL CODING TOO ....

" DIGITAL COMMUNICATION " by BERNERD SKLAR

ITS FAR TOO GOOD IN THESE ... JUST STUDY FROM THERE ...
 

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