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Questions tagged [ldpc]

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What is the role of the low density in LDPC coding?

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 ...
Rokai's user avatar
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Matlab LDPC Decoder: Normal-Min-Sum

I am trying to implement the Min-Sum Decoder for LDPC in Matlab. To check if I do it correctly, I am comparing the output with the min-sum decoder of Matlab. For Matlab's functions I set the ...
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Unable to decode LDPC using Belief Propagation algorithm

I'm writing a MATLAB code to decode LDPC codes using the BP algorithm. I'm trying this with a (7,4) code. I tried the message-passing algorithm between variable and check nodes. L_r is the check to ...
Milli_Wizard369's user avatar
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How to design an optimal LLR Quantization of LLR for LDPC Decoding under AWGN channel using BPSK(Known quantization boundaries)?

Recently I met an optimazition problem, i.e., finding an optimal quantizer which maps floating point LLRs to integers of range $-11,\ldots +11$, where the quantizer boundaries have been calculated out....
Milin's user avatar
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how to use simulators to compute the energy consumption

If I use a open source simulator (OAI 5GNR ULSIM/DLSIM) for realizing a wireless uplink transmission channel and transmits a LDPC coded data. My question is how to use it to compute the energy ...
Anamika's user avatar
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How to use an LDPC encoder implemented in C in MATLAB and which (open source) encoder is most energy-efficient?

I am looking for an open source LDPC encoder available online as I just have to use it for encoding raw bits to LDPC-encoded data to estimate the energy consumption. Which is the best encoder from the ...
Anamika's user avatar
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Energy consumption per bit (in joules) in a LDPC encoder

Can we frame a mathematical model based on the clock frequency (CPU cycles), to compute the energy consumption per bit for a LDPC encoder?
Anamika's user avatar
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Comparing communication systems with different modulation orders and code rates

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 ...
tuna's user avatar
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Generate 5G compliant parity check matrix and save it to .alist file

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 ...
JonPC's user avatar
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How to correctly accept Polar/LDPC encoded bits with PSK modulation?

I have implemented a packet reception and transmission scheme using QPSK. Next I decided to add Polar/LDPC encoding. As a result, nothing is written to the received file. I think the thing is that I'm ...
Ice Cool's user avatar
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Matlab LDPC Decoder Problem with LLRs

I am trying to implement the Belief Propagation (Sum-product algorithm) to decode LDPC codes in Matlab. I have implemented the equations correctly and did a comparison between my implementation and ...
Cooltafel's user avatar
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Non Gaussian noise in communication system

I took some signal from the real hardware. I have an amplifier which provides non linearity in my resulting signal. Suppose, I have an algorithm which iteratively suppress this nonlinear effects and ...
asd's user avatar
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1 answer
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Is there an optimal way to quantize log-likelihood ratios of an AWGN channel?

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{...
austin's user avatar
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1 answer
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Verifying LDPC matrices in CCSDS blue book

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 ...
austin's user avatar
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Setting Parity Check Matrix for LDPC channel coding

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 ...
Fatima_Ali's user avatar
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Column operations in LDPC generator matrix

I'm trying to produce a generator matrix from a starting low density parity check matrix. There are lots of references on the topic (including this Signal Processing Stack Overflow answer here). They ...
Eric C.'s user avatar
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