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# 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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### Notes or books to quickly get started on the basics of signal processing or wireless communication

I'll soon start working in signal processing, specially wireless communication systems. Hence I'd like to get a quick understanding of MIMO and related systems, for example, the topics like: 1) where ...
18 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 ...
2k views

### Capacity of cascade binary symmetric channels

Let's imagine that we have interconnected in cascade $L$ binary symmetric channels each with the same transition probability $p(y|x) \in \{p, q=1-p\}$, where the output of each BSC is connected to the ...
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### Nyquist noiseless channel capacity; how can bit-rate be two times the bandwidth?

I'm confused by the Nyquist channel capacity formula. How can channel maximum capacity approach double the bandwidth. $C = 2\times BW \times log_{2}(L)$ bits/sec The way it was explained to me ...
19 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). ...
64 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 ...
50 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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### 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 ...
106 views

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### 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 ...
125 views

### GNU Radio | Async FEC encoder/decoder loopback | Issue during decoding?

I have implemented a loopback flowgraph intending to perform the following: FEC encode (repetition code) an input stream in16_2.dat Store the encoded stream as <...
107 views

### Getting the bitstream of an unknown RF signal

I am trying to get the bitstream of a signal sent over 433MHz. I have installed SDR# (I'm on Windows), connected my NESDR SMART, and I identified the signal here: I can see there is only one peak ...
81 views

### Can we break the Shannon capacity? [duplicate]

I have a friend working in wireless communications research. He told me that we can transmit more than one symbol in a given slot using one frequency (of course we can decode them at the receiver). ...
22 views

### Parity Check matrix from degree and check nodes polynoms, LDPC codes

I'm trying to simulate LDPC codes which were optimized for the BEC channel. I generated the degree and check nodes polynomials according to chapter 3.15 in "Modern Coding Theory" by Richardson and ...
19 views

### Punctured Turbo Code Decoding: Convergence Issue

I have been trying to create a basic BCJR decoder for a rate (1/2) punctured turbo code. The puncturing is simple, the encoder alternatively selects between the parity bits generated by the two ...
23 views

### Two inputs channel capacity

Assume that we have an AWGN channel with two inputs (A,B) and the o/p is written as Y = A + g B + Z where Z is an independent Gaussian noise with zero mean and unit variance and g is a constant ...
54 views

### 5G NR base matrix

The 5G NR specs for channel code are found here: https://www.etsi.org/deliver/etsi_ts/138200_138299/138212/15.02.00_60/ts_138212v150200p.pdf Starting on page 21 there is base matrix for the LDPC code ...
17 views

### operations valid for predicting new codewords for a Linear block code having linear encoder mapping

I want to know which operations are valid for predicting/finding a new codeword from a set of known codewords for a linear block code having linear encoder mapping, for eg.: Consider a linear ...
14 views

### Calculating the Channel state information for localization

I want to build a localization system using 4G LTE for a project. Intuitively, I can get the position measuring the time a signal leaves the Base Station to the User Equipment. Knowing that these ...
111 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 ...
37 views

### Sampling vs repetition code

I'm working on a multiuser wireless system simulation and have run into something regarding sampling rates. From everything I've known for a matched filter receiver, the correlation step is performed ...
127 views

### 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 ...
42 views

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### Can we break the Shannon capacity?

I have a friend working in wireless communications research. He told me that we can transmit more than one symbol in a given slot using one frequency (of course we can decode them at the receiver). ...
31 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?
83 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 ...
88 views

### Unambiguously detecting (not correcting) between $t+1$ and $2t$ errors in a Reed-Solomon message

I know that Reed-Solomon codes of the form $(N,N-2t)$ can correct up to $t$ errors, and detect up to $2t$ errors, but I've only seen the correction procedure: Berlekamp-Massey or Euclidean to get the ...
104 views

### Viterbi Algorithm - Selecting survivor paths which both contain the same Hamming distance

To my (limited) knowledge, when determining which survivor path to choose to produce an error-corrected output of a binary Viterbi decoder, the path with the smallest Hamming distance is the most ...
88 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 ...