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Questions tagged [channelcoding]

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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.

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I have a BCH decoder which solve KES equation using RiBM algorithm, the RiBM Code in matlab is follows: ...
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recently I'm working on the Shortened Reed-Solomon code, the original codes was written by Miroslav Marinkovic, which is good source for me, in the decoder part, the author use the following code to ...
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I'm working on RS Enc&Dec, for decoder, I use Reformulated inversionless Berlekamp-Massey (RiBM) algorithm to obtain $\Lambda$ and $\Omega$. However, the original RiBM needs $2t$ iterations (here, ...
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I'm interested in understanding the prevalence of single-bit shift errors—situations where a bit moves to an adjacent position without any insertion or deletion of bits—in practical systems. For ...
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I have written a basic Viterbi decoder in MATLAB (for decoding convolutional codes), which currently assumes an unlimited traceback length. That works fine, but practical (hardware) implementations ...
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Which one is the correct shanon capacity law equation? Or : Thank you for helping, High schooler
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Why does the density of 1 in LDPC codes need to be low? How do decoding algorithms take advantage of such low density? What about we applying the same LDPC iterative decoding to any other parity check ...
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I was reading about digital transmission, there are many steps namely Analog to Digital conversion Source coding Channel coding Line coding Pulse shaping Modulation Multiple access techniques Out of ...
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I propose an end-to-end communication method in my research. The key part of the method is not the channel coding and modulation but we use them anyway. I am using 1/3 rate Turbo codes with QPSK and ...
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Could you please tell me what would be the benefit of using Raw BER (or uncoded BER) in comparison to BER? Thanks
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Recently I meet the following question: Let $X\in {\mu_1,\mu_2,\cdots,\mu_m}$, $Y \in {R_1,R_2,\cdots,R_n}$, where $\mu_i, i = 1,2,\cdots,m$ is means of $m$ gauss probablity density function, $Y$ is ...
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I am trying to think of a way in which the base station (BS) can send say 100 bits of feedback to devices in my cell. My confusion is what is a good way to send this feedback bits. This is during the ...
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My aim is to try out the 5G LDPC codes by using the aff3ct library. This library needs the parity check matrix loaded from a .alist or a .gc file to create the LDPC encoder. I've been looking how to ...
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I'm trying to understand "interleaving" from a theoretical point of view. This paper claimed that by sufficient long interleaving, the channel can be treated as memoryless. Does this holds ...
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According to the Reed-Solomon Wikipage, the RS code can correct up to $\lfloor\frac{t}{2}\rfloor$. While I was playing around with Reed-Solomon FEC (github repo), I noticed that sometimes the RS(544, ...
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How we can prove that the t-error-correcting Reed-Solomon code with symbols from $GF(2^m)$ generated by $$g(X)=(X+\alpha)(X+\alpha^2)...(X+\alpha^{2t})$$ has minimum distance exactly $2t+1$ where $\...
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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 ...
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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 ...
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I am tasked in an assignement to select an appropriate rate 1/2 convolution code for a QAM modulated transmitter with the following setup, However, from my understanding of codes and modulation they ...
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I am seeking to understand, exactly, how to calculate a soft MLL output from a received BPSK signal, and what information is needed. I would like to implement turbo coding in my system, but the ...
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I have been doing a matlab simulation of a VLC (visible light communication) system that uses OOK for the modulator. I have to explain the basic knowledge behing the simulation and I´m having lots of ...
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I'm trying to understand the $\\E_b/N_o$ concept and how different coding rates affect it. I've read a bunch of topics, specifically this and this, but I'm still missing something to have a clear ...
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I have to implement a paper where the author in the simulation section has only mentioned the free distance and states(constraint length) of the convolutional code. I have searched the 3GPP ...
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Keep coming across the term channel knowledge (specifically in the transmitter) in a reading for class but can't really grasp the idea and don't see a clear cut definition. From what I understand it ...
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Given is an analogue source $x$ equally distributed in the interval $[-1;+2]$. By means of a mapping, the signal $Y$ is calculated according to $Y = (X - 1)^3$ is generated. Sketch the $PDF$ of the ...
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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 ...
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I have a question about the decoding of convolutional codes with the MAP (BCJR) algorithm. Let $\mathbf{u}$ denote the uncoded bits and $\mathbf{v}$ is the coded bits. Here is the point! Let $\mathbf{...
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I am working with the 5G NR polar code and have implemented the CRC-Aided Successive Cancellation List decoder based on this paper (Tal et al. 2012). As my decoder is only used to decode a limited ...
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Okay, everyone here knows that my thing was audio and that I have never gotten paid to do anything regarding communications systems. So, while I know a thing or two about DSP and even a little about ...
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This time, I have been reading a lot about how LoRa works and how it is able to achieve such long ranges in non-LOS propagation channels. However, a simple doubt arises regarding the way they ...
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This question may be interpreted as a second part of this other question. Basically, if we encode our data using Huffman's encoding and we want to introduce some FEC afterwards, unless we use a ...
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In this figure from Fundamentals of Digital Communications by Madhow , pp 328 there is a comparison of a rate 1/3 turbo code with the shannon limit for rate 1/3 BPSK: Trying to understand the limit ...
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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_{...
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I am new to this site, which I joined with the aim of finding someone to help me with a little doubt. I am trying to design a system that must be able to work at extremely low (the lower, the better, ...
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My understanding is that given an AWGN channel and BPSK modulation, an LDPC decoder that uses message passing takes as input log-likelihood ratios $L$ of the following form by Bayes' rule: $$ L=\frac{...
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My understanding is that LDPC is a linear block code such that its generator matrix $\mathbf{G}$ and parity check matrix $\mathbf{H}$ satisfy $\mathbf{GH}^T=0$. I am using the CCSDS blue book here as ...
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Suppose the original code is a 2-bit binary coding with 3 possible alphabet. \begin{align} a&\rightarrow 00\\ b&\rightarrow 10\\ c&\rightarrow 11 \end{align} Is that $\operatorname{Hamming}...
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We send the data in bytes to the RS Encoder block. The RS Encoder block encodes the data with the Reed Solomon (255,223) code. It waits for 223 bytes and after this encode them to make a codeword of ...
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I am studying the channel coding theory. The channel coder adds redundant information to the input signal, that helps a decoder to reconstruct the signal. BUT: Can encoder help to eliminate effects ...
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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 ...
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We are usually asked about the full system bit rate. However, we use channel encoding in practical systems, for example conventional coding with rate $(1/3)$. My question is about the full system bit ...
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I am trying to understand the algorithms of channel coding. Regarding the conventional channel which is, for me, the easiest one to implement, I have a question regarding the output of its decoder. ...
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I am trying to implement the LDPC code for OFDM system, where I input data should be binary of length $1024$ and the output coded data of length $2048$ (means of rate 1/2). As known in Matlab ...
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I am working on OFDM over harsh channel, so the channel coding is an essential thing for achieving a reliable communication. According to my reading, LDPC is almost the best channel coding we can use ...
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I am new to encoding in audios and i have searched for ulaw and alaw and found there is conversion from audio to this encoding CCITT alaw/ulaw and as i have known alaw/ulaw belongs to ITUT group not ...
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I was reading on my lecture slides about how to achieve diversity (i.e. transmit more copies of the same message in order to avoid its corruption; this technique may be realized by repeating the ...
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Generally, when using channel encoding followed by interleaving, that process should be performed before the modulator and the system structure should be like that : For me, I only use the ...
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pretty much new here. This question comes from an Online course quiz which i have already completed but cant seem to get a good sleep over, just because i cant figure it out. Below is the question ...
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I am trying to implement a digital communication system as a learning exercise. For error correction, I am using two concatenated codes (RS and convolutional). However, I read that, in order to reduce ...
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For observation $y$, channel coefficient $h$ and gaussian noise $w \sim \mathcal{CN}(0,\sigma^2)$, $$y = hx + w \tag{1}$$ Note that for OFDM system, (1) is assumed channel input-ouput equation on ...
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