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Many changes here and there. I lost track... :-(

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Current work is on MLSE and SD Decoding etc. MLSE is currently not 100% working, the scalings are maybe off?!
This commit is contained in:
Silas Oettinghaus
2025-08-11 07:42:04 +02:00
parent 09d9e5011c
commit 5dbc48abc0
37 changed files with 1506 additions and 570 deletions
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32
Functions/Metrics/calc_ngmi.m
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@@ -1,5 +1,5 @@
function [GMI,NGMI] = calc_ngmi(test_signal,reference_signal,options)
% Silas implementation of (N)GMI calculation according to: J. Cho, L. Schmalen, und P. J. Winzer,
% Silas implementation of (N)GMI calculation according to: J. Cho, L. Schmalen, und P. J. Winzer,
% „Normalized Generalized Mutual Information as a Forward Error Correction Threshold for Probabilistically Shaped QAM“,
% in 2017 European Conference on Optical Communication (ECOC), Sep. 2017, doi: 10.1109/ECOC.2017.8345872.
@@ -38,7 +38,7 @@ end
assert(length(test_signal) == length(reference_signal),"Sequence length does not match");
%%% implemented according to [1] J. Cho, L. Schmalen, und P. J. Winzer,
%%% implemented according to [1] J. Cho, L. Schmalen, und P. J. Winzer,
% „Normalized Generalized Mutual Information as a Forward Error Correction Threshold for Probabilistically Shaped QAM“,
% in 2017 European Conference on Optical Communication (ECOC), Sep. 2017, S. 1–3. doi: 10.1109/ECOC.2017.8345872.
@@ -62,7 +62,7 @@ end
m = log2(M); %bits per symbol
entries = sum(~isnan(received_sd),2)';
P_X = entries./N;
P_X = ones(1,M)/M;%entries./N;
% Parameters
symbols = constellation'; % PAM-4 symbols
@@ -75,18 +75,20 @@ end
% Entropy term
H_X = -sum(P_X .* log2(P_X)); % Entropy of input distribution
% GMI computation
noise_impact_term = 0;
for k = 1:N
y_k = test_signal(k); % Current received sample
[~, closest_symbol_idx] = min(abs(symbols - y_k)); % Closest symbol index
closest_symbol = symbols(closest_symbol_idx); % Closest symbol
tx_bits = PAMmapper(M,0,"eth_style",0).demap(reference_signal);
for i = 1:m
% GMI computation
bit_llr_sum = 0;
for k = 1:N %loop over signal
y_k = test_signal(k); % Current received sample
% [~, closest_symbol_idx] = min(abs(symbols - y_k)); % Closest symbol index
for i = 1:m %loop over bit position
% Extract i-th bit for each symbol
bit_mask = gray_bits(:, i); % Binary column for i-th bit of all symbols
matching_symbols = symbols(bit_mask == gray_bits(closest_symbol_idx, i));
% matching_symbols = symbols(bit_mask == gray_bits(closest_symbol_idx, i)); %old, based on decision that mihht be wrong
matching_symbols = symbols(bit_mask == tx_bits(k,i)); %new, based on tx bits
% Numerator: Sum over x in x_{b_{k, i}}
numerator = sum(q_Y_given_X(y_k, matching_symbols) .* P_X(ismember(symbols, matching_symbols)));
@@ -95,15 +97,15 @@ end
denominator = sum(q_Y_given_X(y_k, symbols) .* P_X);
% Logarithmic contribution
noise_impact_term = noise_impact_term + log2(numerator / denominator);
bit_llr_sum = bit_llr_sum + log2(numerator / denominator);
end
end
% Normalize the noise impact term by N
noise_impact_term = noise_impact_term / N;
bit_llr_sum = bit_llr_sum / N;
% GMI
GMI = H_X + noise_impact_term;
GMI = H_X + bit_llr_sum;
NGMI = GMI / m;
end