This example shows the BER performance improvement for QPSK modulation when using log-likelihood ratio (LLR) instead of hard-decision demodulation in a convolutionally coded communication link.

The LTE Symbol Demodulator block demodulates complex data symbols to data bits or log likelihood ratios (LLR) values based on the modulation types supported by LTE standard TS 36.211 [1].

Convert transmit data to soft bits. Fillers in the transmit data do not have log likelihood ratio (LLR) soft bits.

The implementation of the belief propagation algorithm is based on the decoding algorithm presented by Gallager [2]. In each iteration, the key components of the algorithm are updated based on these equations: At the end of each iteration, ) contains the updated estimate of the LLR value for transmitted bit .

The NR Symbol Demodulator block demodulates complex data symbols to data bits or log likelihood ratios (LLR) values based on the modulation types supported by 5G New Radio (NR) standard TS 38.211 [1].

This model shows the improvement in BER performance when using log-likelihood ratio (LLR) instead of hard decision demodulation in a convolutionally coded communication link. For a MATLAB® version of this example, see Log-Likelihood Ratio (LLR) Demodulation.

The DVB-S2 Symbol Demodulator block demodulates complex data symbol to log-likelihood ratio (LLR) values or data bits based on the modulation types supported by the Digital Video Broadcast Satellite Second Generation (DVB-S2) standard [1].

LLRNet uses a neural network to estimate the exact LLR values given the baseband complex received symbol for a given SNR value. A shallow network with a small number of hidden layers has the potential to estimate the exact LLR values at a …

Nov 2, 2020 · in matlab. the function qamdemod does have the llr calculation feature. but that is just the simplest llr calculation . what if the channel h is not 1

Mar 9, 2011 · llr = calc_llr (llr_demod_obj,r,noise_var); % calculate llr values # New: Noise_var don't have to be a scalar value, but may be a vector of the same length as vector r.