Add PAMmapper bit mapping and Gray penalty visualization

Classes/01_transmit/PAMmapper.m

@@ -504,9 +504,118 @@ classdef PAMmapper
 
         end
 
-        function bitmap = showBitMapping(obj)
+        function [ax, mapping_table] = plotBitMapping(obj)
+            [constellation, bitmap] = obj.getConstellationBitMapping();
+            constellation = constellation .* obj.get_scaling;
+            bit_labels = string(cellstr(char(bitmap + '0')));
 
-            bitmap = obj.demap((obj.levels ./ obj.scaling)');
+            if obj.M == 6
+                [~, order] = sortrows([-constellation(:,2), constellation(:,1)]);
+                constellation = constellation(order, :);
+                bit_labels = bit_labels(order);
+
+                mapping_table = table(constellation(:,1), constellation(:,2), bit_labels, ...
+                    'VariableNames', {'symbol_1', 'symbol_2', 'bits'});
+
+                fig = figure("Name", sprintf("PAM-%d Bit Mapping", obj.M));
+                ax = axes(fig);
+                scatter(ax, constellation(:,1), constellation(:,2), 60, "filled");
+                hold(ax, "on");
+                grid(ax, "on");
+                box(ax, "on");
+
+                x_step = min(diff(unique(constellation(:,1))));
+                y_step = min(diff(unique(constellation(:,2))));
+                text(ax, constellation(:,1), constellation(:,2) + 0.18*y_step, bit_labels, ...
+                    "HorizontalAlignment", "center", "FontName", "Consolas");
+
+                xlabel(ax, "Symbol 1");
+                ylabel(ax, "Symbol 2");
+                title(ax, sprintf("PAM-%d Mapping", obj.M));
+                axis(ax, "equal");
+                xticks(ax, unique(constellation(:,1)));
+                yticks(ax, unique(constellation(:,2)));
+                xlim(ax, [min(constellation(:,1)) - 0.8*x_step, max(constellation(:,1)) + 1.4*x_step]);
+                ylim(ax, [min(constellation(:,2)) - 0.6*y_step, max(constellation(:,2)) + 0.9*y_step]);
+            else
+                constellation = constellation(:);
+                mapping_table = table(constellation, bit_labels, ...
+                    'VariableNames', {'symbol', 'bits'});
+
+                fig = figure("Name", sprintf("PAM-%d Bit Mapping", obj.M));
+                ax = axes(fig);
+                scatter(ax, constellation, zeros(size(constellation)), 60, "filled");
+                hold(ax, "on");
+                grid(ax, "on");
+                box(ax, "on");
+                text(ax, constellation, 0.08*ones(size(constellation)), bit_labels, ...
+                    "HorizontalAlignment", "center", "FontName", "Consolas");
+
+                xlabel(ax, "Symbol");
+                title(ax, sprintf("PAM-%d Mapping", obj.M));
+                yticks(ax, []);
+                ylim(ax, [-0.2 0.2]);
+                xticks(ax, constellation);
+                if numel(constellation) > 1
+                    x_step = min(diff(unique(constellation)));
+                else
+                    x_step = 1;
+                end
+                xlim(ax, [min(constellation) - 0.8*x_step, max(constellation) + 0.8*x_step]);
+            end
+
+            if nargout == 0
+                disp(mapping_table);
+            end
+        end
+
+        function bitmap = showBitMapping(obj)
+            [~, bitmap] = obj.getConstellationBitMapping();
+
+        end
+
+        function [Gp, details] = graypenalty(obj)
+            [constellation, bit_labels] = obj.getConstellationBitMapping();
+
+            num_points = size(constellation, 1);
+            dist2 = inf(num_points);
+
+            for idx = 1:num_points
+                delta = constellation - constellation(idx, :);
+                dist2(idx, :) = sum(delta.^2, 2).';
+            end
+
+            dist2(1:num_points+1:end) = inf;
+            min_dist2 = min(dist2(:));
+            is_neighbor = abs(dist2 - min_dist2) < 1e-12;
+
+            hamming_dist = zeros(num_points);
+            for idx = 1:num_points
+                hamming_dist(idx, :) = sum(bit_labels ~= bit_labels(idx, :), 2).';
+            end
+
+            Gp = sum(hamming_dist(is_neighbor)) / nnz(is_neighbor);
+
+            if nargout > 1
+                details = struct( ...
+                    "constellation", constellation, ...
+                    "bit_labels", bit_labels, ...
+                    "neighbor_mask", is_neighbor, ...
+                    "nearest_distance", sqrt(min_dist2));
+            end
+
+        end
+
+        function [constellation, bitmap] = getConstellationBitMapping(obj)
+
+            if obj.M == 6
+                constellation = obj.thresholds ./ obj.scaling;
+                bitmap = obj.demap(reshape(constellation.', [], 1));
+                bitmap = reshape(bitmap, 5, []).';
+            else
+                constellation = (obj.levels ./ obj.scaling)';
+                bitmap = obj.demap(constellation);
+            end
 
         end
 

Functions/EQ_structures/dsp_scope_signal.m

@@ -97,7 +97,7 @@ function output = dsp_scope_signal(Scpe_sig_raw, Symbols, Tx_bits, options)
 
             ffe_results = ffe(eq_dfe, M, Scpe_sig, Symbols, Tx_bits, ...
                 "precode_mode", duob_mode, ...
-                'showAnalysis', showAnalysis, ...
+                'showAnalysis', options.debug_plots, ...
                 "postFFE", [], ...
                 "eth_style_symbol_mapping", 0);
 
@@ -111,7 +111,7 @@ function output = dsp_scope_signal(Scpe_sig_raw, Symbols, Tx_bits, options)
 
             dfe_results = ffe(eq_dfe, M, Scpe_sig, Symbols, Tx_bits, ...
                 "precode_mode", duob_mode, ...
-                'showAnalysis', showAnalysis, ...
+                'showAnalysis', options.debug_plots, ...
                 "postFFE", [], ...
                 "eth_style_symbol_mapping", 0);
 

Functions/EQ_structures/ffe.m

@@ -180,6 +180,8 @@ function displayAnalysis(eq_noise, eq_signal_sd, rx_signal, eq_, tx_symbols, M,
         legend on
     end
 
+    show2Dconstellation(eq_signal_sd, tx_symbols,"displayname",'Visualization of symbol correlation','fignum',340);
+
     % try
     %     figure(240); hold on; plot(pow2db(movmean(eq_.debug_struct.error_tr',100)));ylim([-30,3]);title('error training');
     % 
@@ -188,6 +190,6 @@ function displayAnalysis(eq_noise, eq_signal_sd, rx_signal, eq_, tx_symbols, M,
     %     figure(242); hold on; plot(pow2db(movmean(eq_.debug_struct.update',1000)));title('update step dd');
     % end
 
-    eq_signal_sd.eye(eq_signal_sd.fs,M,"displayname",'Eye','fignum',105);
+    % eq_signal_sd.eye(eq_signal_sd.fs,M,"displayname",'Eye','fignum',105);
 
 end

Functions/EQ_visuals/show2Dconstellation.m

@@ -30,7 +30,7 @@ end
 rx_symbols = eq_signal; %./ rms(eq_signal);
 correct_symbols = ref_symbols;
 
-col = cbrewer2('Paired',numel(unique(correct_symbols))*2);
+col = cbrewer2('Paired',numel(unique(correct_symbols))*3);
 ccnt = -1;
 
 levels = unique(correct_symbols);

Theory/Mapping_Coding/Gray_penalty.m

@@ -0,0 +1,11 @@
+function [Gp, details] = Gray_penalty(use_eth_mapping)
+%GRAY_PENALTY Average bit errors per nearest-neighbor PAM-6 symbol error.
+
+if nargin < 1
+    use_eth_mapping = 1;
+end
+
+mapper = PAMmapper(6, 0, "eth_style", use_eth_mapping);
+mapper.plotBitMapping();
+[Gp, details] = mapper.graypenalty();
+end

projects/IMDD_base_system/imdd_it.m

@@ -17,30 +17,42 @@ if 1
     
     uloops              = struct;
     uloops.precomp      = [0];
-    uloops.bitrate      = [300].*1e9; %[300,330,360,390,420,450,480] [224,336,360,390,420,448] for MPI
+    uloops.fsym = 180e9;
+    % uloops.bitrate = 100e9;
     % uloops.laser_wavelength = [1293,1297.5,1302,1306.5,1310,1313.4,1318,1322.7,1327.4];
-    uloops.laser_wavelength = [1293];
+    uloops.laser_wavelength = [1310];
-    uloops.M            = [4];
+    uloops.M            = [6];
     uloops.link_length  = 1;
     % uloops.link_length  = [0:2:10]; % 1,2,3,5,6,8,10
-    uloops.channel_alpha = [0.5];
+    uloops.channel_alpha = [0.8];
     uloops.duob_mode = db_mode.no_db;
     uloops.decoding_mode = "memoryless";
-    uloops.channel_mode = "awgn_alphad";
+    uloops.channel_mode = "awgn_alphad"; %awgn_alphad
-    uloops.channel_snr_dB = [20:-2:0];
+    uloops.channel_snr_dB = [20];
+    uloops.rop = -6;
     
     wh = DataStorage(uloops);
     wh.addStorage("ber");
     
-    wh = submit_handle(@imdd_model,wh,"parallel",1);
+    wh = submit_handle(@imdd_model,wh,"parallel",0);
     
 end
 
 %%
 figure
 hold on
+if isfield(uloops, 'fsym') && isfield(uloops, 'bitrate')
+    error('Define only one of uloops.fsym or uloops.bitrate.');
+elseif isfield(uloops, 'fsym')
+    rateLookup = uloops.fsym;
+elseif isfield(uloops, 'bitrate')
+    rateLookup = uloops.bitrate;
+else
+    error('Define either uloops.fsym or uloops.bitrate.');
+end
+
 for alpha = uloops.channel_alpha
-    a=wh.getStoValue('ber',0, [300].*1e9 , 1293, 4, uloops.link_length,alpha,uloops.duob_mode,uloops.decoding_mode,uloops.channel_mode,uloops.channel_snr_dB);
+    a=wh.getStoValue('ber',0, rateLookup, uloops.laser_wavelength, uloops.M, uloops.link_length,alpha,uloops.duob_mode,uloops.decoding_mode,uloops.channel_mode,uloops.channel_snr_dB);
     gmi_ffe = cellfun(@(x) x.ffe_results.metrics.GMI, a);
     alpha_ffe = cellfun(@(x) x.ffe_results.metrics.Alpha, a);
 

projects/IMDD_base_system/imdd_model.m

@@ -12,11 +12,12 @@ end
 %%% Run parameters
 % TX
 M               = 4;
-fsym            = 180e9;
+fsym            = 150e9;
+bitrate         = [];
 
-apply_pulsef    = 1;
+apply_pulsef    = 0;
-fdac            = 256e9;
+fdac            = 4*fsym;%256e9;
-fadc            = 256e9;
+fadc            = 4*fsym;%256e9;
 random_key      = 1;
 
 rcalpha         = 0.05;
@@ -28,7 +29,7 @@ vbias           = -vbias_rel*u_pi;
 
 laser_wavelength    = 1293;
 laser_linewidth     = 0;
-tx_bw_nyquist   = 0.8;
+tx_bw_nyquist   = 0.65;
 
 % Channel
 link_length     = 1;
@@ -38,7 +39,7 @@ channel_alpha = 0;
 channel_delay_symbols = 1;
 
 % RX
-rop = -8;
+rop = 2;
 rx_bw_nyquist = 0.8;
 
 vnle_order1 = 50;
@@ -68,7 +69,7 @@ dfe_ = sum(dfe_order)>0;
 
 duob_mode = db_mode.no_db;
 decoding_mode = [];
-bitrate = fsym * log2(M);
+providedFields = string.empty;
 
 %%% change specific parameter if given in varargin
 % Parse optional input arguments
@@ -76,28 +77,38 @@ if ~isempty(varargin)
     var_s = varargin{1};
     if isstruct(var_s)
         fields = fieldnames(var_s);
+        providedFields = string(fields);
         for i = 1:numel(fields)
-            if isnumeric(fields{i})
+            fieldName = fields{i};
-                eval([fields{i}, ' = ',  num2str( var_s.(fields{i}) ), ';']);
+            if ~isvarname(fieldName)
-                fprintf("%s <-- %.2f \n", fields{i}, var_s.(fields{i}));
+                error('Invalid parameter name "%s".', fieldName);
-            else
-                eval([fields{i}, ' = ',  'var_s.(fields{',num2str(i),'})' , ';']);
             end
-            
+            eval([fieldName, ' = var_s.(fieldName);']);
         end
     else
         error('Optional variables should be passed as a struct.');
     end
 end
 
+hasFsym = any(providedFields == "fsym");
+hasBitrate = any(providedFields == "bitrate");
 
-fsym_ = floor( bitrate*1e-9./log2(M) ).*1e9;
+if M == 6
-
+    bitsPerSymbol = 2.5;
-if fsym_ ~= fsym
+else
-    fsym = fsym_;
+    bitsPerSymbol = log2(M);
-    % fprintf('Adapted symbolrate to %d GBd, to match provided bitrate of %d GBit/s using PAM %d \n',fsym.*1e-9,bitrate.*1e-9, M);
+    if abs(bitsPerSymbol - round(bitsPerSymbol)) > 1e-12
+        error('Unsupported PAM order M=%d. Only powers of two and PAM-6 are supported.', M);
+    end
 end
 
+if hasFsym && hasBitrate
+    error('either bitrate or symbolrate!')
+elseif hasBitrate
+    fsym = bitrate / bitsPerSymbol;
+else
+    bitrate = fsym * bitsPerSymbol;
+end
 
 f_nyquist       = fsym/2;
 
@@ -114,7 +125,6 @@ Pform       = Pulseformer("fsym",fsym,"fdac",4*fsym,"pulse","rc","pulselength",1
 
 Digi_sig.spectrum("displayname",'Digi Spectrum','fignum',10,'normalizeTo0dB',1);
 
-
 channel_mode = lower(string(channel_mode));
 
 switch channel_mode
@@ -122,7 +132,7 @@ switch channel_mode
 
         %%%%% AWG
         % El_sig = M8199A("kover",kover).process(Digi_sig);
-        El_sig = AWG("fdac",fdac,"f_cutoff",fsym,"lpf_active",0,"kover",kover,"bit_resolution",12,"upsampling_method","samplehold","precomp_sinc_rolloff",1).process(Digi_sig);
+        El_sig = AWG("fdac",fdac,"f_cutoff",fsym,"lpf_active",1,"kover",kover,"bit_resolution",12,"upsampling_method","samplehold","precomp_sinc_rolloff",0).process(Digi_sig);
         % El_sig.spectrum("displayname",'Digi Spectrum','fignum',100,'normalizeTo0dB',0);
         % El_sig = El_sig.setPower(0,"dBm");
 
@@ -199,7 +209,6 @@ dspParameters.use_vnle_mlse = 1;
 dspParameters.use_dbtgt = 0;
 dspParameters.use_dbenc = 0;
 dspParameters.use_ml_mlse = 0;
-dspParameters.showAnalysis = 0;
 dspParameters.pf_ncoeffs = pf_ncoeffs;
 dspParameters.ffe_order_ffe = [50, 0, 0];
 dspParameters.ffe_order_dfe = [50, 0, 0];
@@ -217,7 +226,7 @@ scopeOutput = dsp_scope_signal(Rx_sig, Symbols, Tx_bits, ...
     "parameters", dspParameters, ...
     "preprocess_mode", "auto", ...
     "tx_pulseformer", txPulseformer, ...
-    "debug_plots", false);
+    "debug_plots", true);
 
 output = struct();
 output.ffe_results = scopeOutput.ffe_package;
@@ -230,3 +239,4 @@ output.mlmlse_results = scopeOutput.mlmlse_package;
 
 disp('- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ')
 fprintf('\n')
+end