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.

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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 ...
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80 views

Update rule in Soft Output Viterbi Algorithm (SOVA) -Hagenauer rule

Soft output of SOVA, suggested by Hagenauer http://www.cse.lehigh.edu/~jingli/teach/S2003turbo/notes/SOVA.pdf , says in 2.2.2 "The Soft-Output Viterbi Algorithm" that $L_{j}^{\verb|^|}:= f(L_{j}^{\...
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32 views

Degrees of freedom in coding (for a communication channel)

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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56 views

Is MMSE equalizer necessary?

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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16 views

Convolutional coding that payload length does not change

This is the question about Sigfox radio specification. The stack: Specifically, in Section 3.10 of the specification, we have a convolutional coding (after CRC) with three possible polynominals. I ...
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30 views

convolutional coding with higher order QAM

I've implemented a simple 1/2 rate convolutional code and a viterbi decoder algorithm. I followed the most-common type of convolutional coding implementation I could find by googling: 1 input bit gets ...
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101 views

Convolutional FEC decoding - is it necessary to know where a decoding block begins and ends with convolutional codes?

I understand that the difference between convolutional and block-based FEC is that convolutional codes can be used in a continuous stream – however every implementation I saw still uses blocks. So I ...
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702 views

Generating LDPC codes of arbitrary sizes in MATLAB

I am having problems generating LDPC codes of arbitrary sizes in MATLAB primarily because MATLAB insists on the parity check matrix that is input into its ldpcenc ...
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684 views

Is there any formula for coding gain of Turbo code?

I want to compare throughput under different MCS( modulation and coding scheme). We know Shannon capacity $C = B \log(1+SNR)$ can be used to calculate throughput by SNR. However, there is no MCS ...
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1answer
152 views

Is it possible to generate Hamming code with minimum distance $d$ which can correct more than 1 bit error?

In literature, all I am seeing is Hamming code with minimum Hamming distance $3$. Theoretically a Hamming code with minimum distance d can detect $d-1$ errors and can correct $(d-1)/2$ error. So ...
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5 views

LDPC for channel coding

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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15 views

Bad performance of Trellis-Code for low SNR

I have computed the BER-curves for a trellis code with different block lengths in Matlab (using bertool). For small values of $E_b/N_0$, the bit error rate is even worse than without any channel ...
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18 views

Channel coding simulation

I’m new to channel coding, and I’m trying to learn about channel coding in general, and iterative turbo coding in particular. I was trying to play with some simulink examples while reading to get a ...
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32 views

Doubts about Huffman and Shannon - Fano Coding

I was reading these slides about Source Coding and I have the following questions: 1) Let's consider this part: Can you explain me step by step the reasons of a, b, c? Which is the general rule to ...
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30 views

Trellis Termination (zero termination) scheme for RSC encoder

I am currently try to implement a simple RSC encoder in Matlab. As far as I know, this type of channel coding scheme require to reach an all-zero state in the encoder memory element(shift register). ...
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39 views

How to recover 2*Zc systematic bits punctured in LDPC?

In 5G NR LDPC encoder 2Zc systematic bits are punctured at the transmitter end. At the receiver end, it is able to recover all bits excluding the punctured bits at the transmitter end. As the ...
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41 views

How to detect missing bit position in a bit-stream?

I'm trying to establish a one-way communication and facing problem in the receiver end because of some missing bits. For example, if the sender sends 100 bits the receiver received 95/96 bit. Now the ...
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35 views

Convolutional Code: choosing a trellis and puncture pattern for code 2/3

I'm working on convolutional coding in which I'm using generator polynomials as {13, 15} with puncture pattern of {1 1 0 1} for code rate 2/3. I don't get expected BER trend. If I use puncture ...
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1answer
58 views

rate 1/128 channel code for 5 bits of information

I need to construct channel code for 5 bits of information for a wireless channel. Possible code rate could be as low as 1/128 (very reliable). At decoder I assume to use channel LLRs as decoder input ...
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1answer
71 views

Error detection and correction algorithms for Wireless Body Area Networks

I am working on transmitting ECG signals over wireless body area network based on IEEE 802.15.4 standard. To reduce the BER and increase the signal reconstruction quality, I think that I need to ...
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1answer
41 views

Adaptive Predictive Coding: Transmit signal AND prediction coefficients

I'm not well versed in the literature so please forgive/inform me if my terminology is wrong: I have a bounded real-valued, discrete-time signal $x_n \in \mathbb [0, 1]$, and I want to (lossily) ...
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38 views

Applying BCJR equalization for LDPC encoded information

I want to apply BCJR decoder for LDPC encoded information. How can I change the BCJR originally for convolutional codes for this purpose?
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2answers
122 views

Alamouti Scheme. MISO. STBC for real constellation

I have a real orthogonal design for codeword... $$ \begin{bmatrix} s1 & s2 \\ -s2 & s1 \end{bmatrix} $$ $$ s=\begin{bmatrix} s1\\ s2 \end{bmatrix} $$ $$ Y^T=\sqrt{\frac{P}{Mt}} h^T ...
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57 views

Viterbi equalization of Fibonacci coding

I'm working a Viterbi equalizer for a BPSK signal which uses Fibonacci coding. In the more theoretical descriptions of the Viterbi algorithm I've read, there's a term for the probability of a ...
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170 views

Convolving a signal with the impulse response of the channel

For a complex signal x to be transmitted over a channel with complex impulse response h, x will be convolved with h. What will the mathematical operation done in the reveiver to cancel the effect of h?...
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1answer
118 views

resilient codes to phase shift

I need to define an encoding to beacon IDs. The codes are going to be periodic but in the receiver side I can have phase shifts so I' wondering the best way to decode: - 8 bits code groups that ...
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1answer
2k views

Recursive systematic convolutional code (RSC) realization in MATLAB

How can I implement $\rm RSC(2,1,2)$ in MATLAB? Can I use convenc function to build RSC? The convenc function has 2 arguments: ...
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1answer
677 views

Limitations of Arithmetic coding?

I have been working on an assignment for university in which I have to compress an 80K message consisting of only two symbols, 'a' and 'b', having probability values of 0.6 and 0.4. I have ...
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1answer
128 views

Berlekamp–Massey algorithm verification

I'm implementing Berlekamp–Massey algorithm for BCH codes, but I have some troubles with it: I don't realize how to verify this algorithm. Is there any methods to prove, that code works correctly or ...
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138 views

How to write cyclic codes?

I am studying cyclic codes. From what I understood of it, a cyclic code is a special kind of linear code with the property that any codeword cyclic shift is also a codeword. Generally, we start with ...