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

Current work is on MLSE and SD Decoding etc. MLSE is currently not 100% working, the scalings are maybe off?!
2025-08-11 07:42:04 +02:00
parent 09d9e5011c
commit 5dbc48abc0
37 changed files with 1506 additions and 570 deletions
--- a/Functions/Metrics/calc_gmi_bitwise.m
+++ b/Functions/Metrics/calc_gmi_bitwise.m
@@ -0,0 +1,94 @@
+function [GMI,NGMI] = calc_gmi_bitwise(test_signal,reference_signal,options)
+%  https://cioffi-group.stanford.edu/doc/book/AppendixG.pdf
+
+arguments(Input)
+    test_signal;
+    reference_signal;
+    options.skip_front = 0;
+    options.skip_end = 0;
+    options.returnErrorLocation = 0;
+end
+
+options.skip_end = abs(options.skip_end);
+options.skip_front = abs(options.skip_front);
+
+assert((options.skip_end+options.skip_front)<length(test_signal),"You can not skip more bits than overall length of data! Set skip_front or skip_end to lower value or check data_in");
+
+if isa(reference_signal,'Signal')
+    reference_signal = reference_signal.signal;
+end
+
+if isa(test_signal,'Signal')
+    test_signal = test_signal.signal;
+end
+
+% TRIM
+[test_signal,reference_signal]=trimseq(test_signal,reference_signal,options.skip_front,options.skip_end);
+
+% CALC AIR
+%%% new implementation of AIR
+% Precompute
+N       = length(test_signal);
+M       = numel(unique(reference_signal));
+nBits   = log2(M);
+levels  = PAMmapper(M,0).levels / PAMmapper(M,0).scaling;
+grayBits= PAMmapper(M,0).showBitMapping;
+priors  = ones(1,M)/M;
+
+noise   = test_signal-reference_signal;
+sigma2  = var(noise);
+
+% Allocate
+LLR     = zeros(N, nBits);
+rxBits  = zeros(N, nBits);
+
+for n = 1:N
+    y       = test_signal(n);
+    ll_table= -((y - levels).^2)/(2*sigma2) + log(priors);  % M×1
+
+    % Per‐bit LLR
+    for b = 1:nBits
+        idx0 = grayBits(:,b)==0;
+        idx1 = grayBits(:,b)==1;
+        L0   = logsumexp(ll_table(idx0));
+        L1   = logsumexp(ll_table(idx1));
+        LLR(n,b) = L1 - L0;
+    end
+end
+
+tx_bits = PAMmapper(M,0,"eth_style",0).demap(reference_signal);
+
+% Compute GMI (bit‐wise MI averaged over all symbols)
+MI_bits = zeros(1,nBits);
+for b = 1:nBits
+    r0 = LLR(tx_bits(:,b)==0,b);
+    r1 = LLR(tx_bits(:,b)==1,b);
+    I0 = mean( log2(1 + exp(r0)) );
+    I1 = mean( log2(1 + exp( -r1)) );
+    MI_bits(b) = 1 - 0.5*(I0 + I1);
+end
+
+GMI = sum(MI_bits);            % in bits per symbol
+NGMI = GMI / nBits;        % normalized per bit
+
+% Auxiliary nested helper for numerically stable log-sum-exp
+    function s = logsumexp(a)
+        % LOGSUMEXP   Compute log(sum(exp(a))) in a numerically stable way
+        m = max(a);
+        s = m + log(sum(exp(a - m)));
+    end
+
+
+    function [data_,reference_]=trimseq(data,reference,skipstart,skip_end)
+
+        data_  =  data(skipstart+1:end-skip_end,:);
+
+        delta_bits = length(reference) - length(data);
+
+        skip_end = delta_bits + skip_end;
+
+        reference_ = reference(skipstart+1:end-skip_end,:);
+
+    end
+
+end