Signal Processing Stack Exchange
Signal Processing Stack Exchange

Questions tagged [channelcoding]

Questions related to channel coding, forward error correction, code performance calculations, and decoding algorithms. Typical code examples are Hamming codes, cyclic codes, BCH, Reed-Solomon, turbo codes, and LDPC.

In telecommunication, information theory, and coding theory, forward error correction (FEC) or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels. The central idea is the sender encodes the message in a redundant way by using an error-correcting code (ECC). (From Wikipedia.)

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Viterbi decoder on a bit stream where the preamble is also coded

I hope this is not off-topic for this site. In my problem, Viterbi decoder is used for decoding convolutional-coded (rate = 1/2, constraint length = 7) messages. A message is 250 bits where the first 8 bits are 1/3 of a preamble. There are several…
groove
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Code rate in IEEE 802.11b (DSSS)

I would like to know what code rates for forward error correction the physical layer of IEEE 802.11b uses for the different supported data rates. So far I didn't find any source for that. Actually in the literature I found on 802.11b and DSSS code…
Enzo
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Hamming code exercise

I'm preparing for my exams I stumbled across this exercise. Now I can't seem to figure it out. Anybody can help me ? The exercise: For the 8bit data word: 00111001 the check bits are: 0111. Now if the word is read from the memory and the check bits…
Olivier_s_j
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Effect of altering FEC k/n versus symbol rate on BER performance

Let's say I hypothetically have a forward error correction (FEC) code with coding rate $k/n= 1/2$. Let's say it is given for now that for a fixed signal-to-noise ratio (SNR) in an additive white Gaussian noise (AWGN) channel, this hypothetical FEC…
Robert L.
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Generate Minimum distance codes

I am trying to generate a set of linear block codewords of length n and have minimum hamming distance dmin. I understand Hamming codes but they are not flexible with n. One possible way I can think of is brute force search. But when trying to code…
PSK
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Viterbi Decoder - Symbol Alignment

With a 1/2-rate convolutional encoder, $n$ bits are encoded into $2n$ symbols. Assume we have a long encoded stream such as $[... s_0, s_1, s_2, s_3, s_4, s_5, s_6, s_7, s_8, s_9, ..., s_{100}, ...]$. I want to extract a small portion from the…
groove
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code construction process in polar coding

Arikan in his paper (arXiv link or IEEE link) about polar coding, explains how you can force the channel to polarize by applying a linear transformation (the generator matrix). He calls this a split and combine process, where he creates synthetic…
p.storm
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In block codes (channel coding), in practice how is the message length ($k$) fixed?

In block codes (channel coding), in practice, how is the message length ($k$) fixed? If $k$ is large, the practical implementation of it requires huge memory if look up table approach is adopted. What is the disadvantage with short $k$'s? Code…
Seetha Rama Raju Sanapala
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What are the possible forms of generator matrix of a systematic linear block code?

My text book, Communication systems by Simon Haykin says Block codes in which the message bits are transmitted in unaltered form are called systematic codes. I am not getting what it means. A diagram is given below the statement in which parity…
Lelouch Yagami
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Chosing the right type of convolution code for a M-QAM transmitter

Coming from my previous question (link to this here). Given the following transmitter design, with these parameters, bit rate of 55 Mbps maximum bandwidth of 17 MHz code rate : 1/2 minimum SNR to design for 10dB maximum SNR to design for…
albusSimba
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Why are the minimum distances of a code and its interleaved code equal?

I know this is probably a very trivial question, but I am completely stuck. Let $C$ be a linear $[n,k,d]$ Code. Then the interleaving of depth $t$ is the Code $C(t)=\{(c_{11}, \dots, c_{t1}, \dots, c_{1n}, \dots, c_{tn}) \mid (c_{i1}, \dots, c_{in})…
convergence
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Is there better than hamming code for correcting errors

As known, hamming code can be represented by (7,4) where data are 4 bits, and 3 bits for parity, and (15,11) where 11 bits are data and 4 bits for parity. It can correct up to one bit, or detect two bits without correcting. Parity bits will cause…
New_student
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Inter-symbol energy coding

I have scoured my entire library and I can't find where I read about a method of using symbol energy intentionally smeared across multiple bit times in such a way that the symbols can be recovered correctly. Can someone point to any of the classic…
RMack
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What is special about the theorem that over GF(2), $f^2(X) = f(X^2)$?

What is special about the theorem that over GF(2), $f^2(X) = f(X^2)$? There is a some 10-line proof for the same in "page no.42, Shu Lin, Daniel J. Costello-Error Control Coding (2nd Edition)-Prentice Hall (2004)" I think the fact is more general…
Seetha Rama Raju Sanapala
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In cyclic codes, a code vector can be obtained from another by simple circular shift. Why then the other method?

In cyclic codes, a code vector can be obtained from another by simple circular shift. Why then the other method is taught that is a bit round about? Take the code polynomial. Multiply it by the polynomial with power equal to the circular shift…
Seetha Rama Raju Sanapala
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