New MPI mitigation schemes // Duobinary // Start of FTN schemes

This commit is contained in:
Silas Oettinghaus
2024-09-06 08:10:04 +02:00
parent bb228ae2bd
commit 03bfd70470
30 changed files with 1598 additions and 560 deletions

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classdef EQ
%EQ Summary of this class goes here
% Detailed explanation goes here
properties
Ne %Number of feed forward coefficients (1st, 2nd and 3rd order)
Nb %Number of decision feedback coefficients (1st, 2nd and 3rd order)
K %Number of samples per symbol
delay %Delay of incoming signal
training_length %Number of training symbols
training_loops %Number of loops through sequence for training mode
ideal_dfe %Error free DFE decisions
DB_aim %Aim at duobinary output sequence
M %Order of the PAM constellation (only relevant in case of DB aim)
FFEmu %mu parameter for FFE part in training mode (0 means normalized LMS)
DFEmu % mu parameter for DFE part in training mode
dd_loops % Number of loops through sequence for DD mode
DDmu % mu parameters for DD mode (individual value for each order)
DCmu % mu parameter for the dc tap
l1act %Activate/deactive l1 regularization
rho %Parameter for speed of coeff shrinking
epsilon %Reciprocal value of the magnitude of the coeff to converge to zero (1st,2nd,3rd order)
thres %Theshold for neglecting coefficienties (1st,2nd,3rd order)
static_act %Activate/deactive static coefficient reduction
mode2nd %0: no reduction | 1: polynomial | 2: restricted to interval
len_2nd %length of the interval (only for 2nd order mode = 2)
mode3rd %0: no reduction | 1: polynomial | 2: restricted to interval
len_3rd %length of the interval (only for 3rd order mode = 3/4)
plottrain
plotfinal
load_decisions
save_taps
%during simulation
k0
b
b2
b3
e
e2
e3
coeff_number
constellation_in
error_log
end
methods
function obj = EQ(options)
%EQ Construct an instance of this class
% Detailed explanation goes here
arguments(Input)
options.Ne = [10 0 0] %Number of feed forward coefficients (1st, 2nd and 3rd order)
options.Nb = [10 0 0]%Number of decision feedback coefficients (1st, 2nd and 3rd order)
options.K = 1 %Number of samples per symbol
options.delay = 0 %Delay of incoming signal
options.training_length = 1024 %Number of training symbols
options.training_loops = 1 %Number of loops through sequence for training mode
options.ideal_dfe = 0 %Error free DFE decisions
options.DB_aim %Aim at duobinary output sequence
options.M = 1 %Order of the PAM constellation (only relevant in case of DB aim)
options.FFEmu = 0 %mu parameter for FFE part in training mode (0 means normalized LMS)
options.DFEmu = 0.005 % mu parameter for DFE part in training mode
options.dd_loops = 1% Number of loops through sequence for DD mode
options.DDmu = [0.0004 0.0004 0.0004 0.0004 ] % mu parameters for DD mode (individual value for each order)
options.DCmu = 0.005 % mu parameter for the dc tap
options.l1act = 0 %Activate/deactive l1 regularization
options.rho = 5e-4%Parameter for speed of coeff shrinking
options.epsilon = [10 100 1000] %Reciprocal value of the magnitude of the coeff to converge to zero (1st,2nd,3rd order)
options.thres = [5e-3 4e-3 5e-4]%Theshold for neglecting coefficienties (1st,2nd,3rd order)
options.static_act = 0 %Activate/deactive static coefficient reduction
options.mode2nd = 1%0: no reduction | 1: polynomial | 2: restricted to interval
options.len_2nd = 1 %length of the interval (only for 2nd order mode = 2)
options.mode3rd = 1%0: no reduction | 1: polynomial | 2: restricted to interval
options.len_3rd = 1%length of the interval (only for 3rd order mode = 3/4)
options.plottrain = 0
options.plotfinal = 0
options.load_decisions = 0
options.save_taps = 0
end
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
end
function [signalclass_out,error_log] = process(obj,signalclass_in, reference_signalclass_in)
% actual processing of the signal (steps 1. - 3.)
[signalclass_in.signal,error_log] = obj.process_(signalclass_in.signal', reference_signalclass_in.signal');
signalclass_in.signal = signalclass_in.signal';
% append to logbook
lbdesc = ['EQ '];
signalclass_in = signalclass_in.logbookentry(lbdesc);
% write to output
signalclass_out = signalclass_in;
end
function [yout,error_log] = process_(obj,data_in,ref_in)
%METHOD1 Summary of this method goes here
% Detailed explanation goes here
if obj.DB_aim
ref_DB = zeros(size(ref_in));
for k = 1:length(ref_in)
if k == 1
ref_DB(k) = ref_in(k);
else
ref_DB(k) = ref_in(k) + ref_in(k-1);
end
end
ref_in = ref_DB;
end
ref = [zeros(1,obj.Nb(1)-1) ref_in zeros(1,obj.Nb(1))];
if isreal(ref)
cplx = 0;
else
cplx = 1;
end
if obj.static_act
obj.mode2nd = obj.mode2nd + 1;
obj.mode3rd = obj.mode3rd + 1;
else
obj.mode2nd = 1;
obj.mode3rd = 1;
end
if obj.mode2nd == 1
N2 = (obj.Ne(2)*(obj.Ne(2)+1))/2; % Number of coefficients for second order
elseif obj.mode2nd == 2
N2 = obj.Ne(2);
elseif obj.mode2nd == 3
N2 = (obj.len_2nd+1)*(2*obj.Ne(2)-obj.len_2nd)/2;
elseif obj.mode2nd == 4
N2 = (ceil(obj.Ne(2)/2)+1)*(2*obj.Ne(2)-ceil(obj.Ne(2)/2))/2;
end
if obj.mode3rd == 1
if cplx
N3 = obj.Ne(3)^2*(obj.Ne(3)+1)/2;
else
N3 = obj.Ne(3)*(obj.Ne(3)+1)*(obj.Ne(3)+2)/6; % Number of coefficients for third order
end
elseif obj.mode3rd == 2
N3 = obj.Ne(3);
elseif obj.mode3rd == 3
N3 = obj.Ne(3)^2;
elseif obj.mode3rd == 4
N3 = round(1/6*(obj.len_3rd+1)*(obj.len_3rd+2)*(3*obj.Ne(3)-2*obj.len_3rd));
elseif obj.mode3rd == 5
N3 = 2*obj.Ne(3)*obj.len_3rd-obj.len_3rd*(obj.len_3rd+1)+obj.Ne(3);
end
Nb2 = (obj.Nb(2)*(obj.Nb(2)+1))/2;
Nb3 = obj.Nb(3)*(obj.Nb(3)+1)*(obj.Nb(3)+2)/6;
data_in = data_in/sqrt(mean(abs(data_in).^2)); % power normalization of input sequence
if obj.FFEmu == 0
norm_fac2 = sqrt(mean(abs(data_in.^2).^2)); % power normalization for second and third order terms
norm_fac3 = sqrt(mean(abs(data_in.^3).^2)); % (not necessary, but seems to be more stable if applied --> same as different mu values for linear and nl terms)
else
norm_fac2 = 1;
norm_fac3 = 1;
end
norm_fac_DFE2 = sqrt(mean(abs(ref_in.^2).^2)); % same for DFE input (reference)
norm_fac_DFE3 = sqrt(mean(abs(ref_in.^3).^2));
data = [zeros(1,floor(obj.Ne(1)/2)) data_in zeros(1,obj.Ne(1))];
delta_2 = round((obj.Ne(1)-obj.Ne(2))/2);
delta_3 = round((obj.Ne(1)-obj.Ne(3))/2);
delta_DFE2 = 1;%round((obj.Nb-obj.Nb(2))/2);
delta_DFE3 = 1;%round((obj.Nb-obj.Nb(3))/2);
% calculate the indices for the combination of second and third order symbols
% - done in advance because it's the same for each iteration, so time
% can be saved
[ind_mat_2nd,ind_mat_3rd] = obj.calc_ind(obj.Ne(2),N2,obj.Ne(3),N3,obj.mode2nd,obj.mode3rd,obj.len_2nd,obj.len_3rd,cplx);
[ind_mat_DFE_2nd,ind_mat_DFE_3rd] = obj.calc_DFE_ind(obj.Nb(2),Nb2,obj.Nb(3),Nb3);
if obj.l1act
epsilon_ = diag([ones(1,obj.Ne(1))*obj.epsilon(1) ones(1,N2)*obj.epsilon(2) ones(1,N3)*obj.epsilon(3)]);
end
obj.k0 = obj.delay; % input delay compared to training sequence
error_log = [];
if 1 % obj.active
%% Calculation of the filter coefficients in training based LMS mode
e_ = zeros(obj.Ne(1)+N2+N3,1); % initialization of filter coefficients
b_ = zeros(obj.Nb(1)+Nb2+Nb3,1);
e_dc = mean(data_in); % initilaization of the dc tap with the mean value of the whole data
for trainloops = 1:obj.training_loops
cnt = 1;
m = obj.k0+1; % starting symbol index at the delay compared to the training sequence
% n => index in rx data sequence
%Step From: Oversampling(=2) * Startdelay + 1
%Step Width: Oversampling(=2)
%Step To: Oversampling(=2) * Training Length
for n = obj.K*obj.k0+1:obj.K:obj.K*obj.training_length
% m => index in reference sequence
m = m+1;
%
%dc_ = mean(data(obj.Ne(1)+n+(obj.K-1):-1:n+obj.K).');
% cut symbols from rx data sequence
X_1 = data(obj.Ne(1)+n+(obj.K-1):-1:n+obj.K).';
[X_2,X_3] = obj.calc_nl_vecs(X_1,ind_mat_2nd,ind_mat_3rd,norm_fac2,norm_fac3,delta_2,delta_3,cplx);
input_vec = [X_1;X_2;X_3];
% cut symbols from desired data sequence (correct symbols in training mode)
D_1 = ref(obj.Nb(1)-obj.k0+m-2:-1:m-obj.k0-1).';
[D_2,D_3] = obj.calc_nl_vecs(D_1,ind_mat_DFE_2nd,ind_mat_DFE_3rd,norm_fac_DFE2,norm_fac_DFE3,delta_DFE2,delta_DFE3,cplx);
reference_vec = [D_1;D_2;D_3];
e_ffe = e_.'*input_vec;
e_dfe = b_.'*reference_vec;
error = e_dc + e_ffe - e_dfe - ref_in(m-obj.k0);
%error = e_dc + e_.'*input_vec - b_.'*reference_vec - ref_in(m-obj.k0);
if real(obj.FFEmu)
if obj.l1act
sgn_e = e_;
sgn_e(e_~=0) = e_(e_~=0)./abs(e_(e_~=0));
e_ = e_ - obj.rho*sgn_e./(1+epsilon_*abs(e_)) - error*input_vec*obj.FFEmu;
else
e_ = e_ - error*conj(input_vec)*obj.FFEmu; %classic LMS gradient decay
end
else
if obj.l1act
sgn_e = e_;
sgn_e(e_~=0) = e_(e_~=0)./abs(e_(e_~=0));
e_ = e_ - obj.rho*sgn_e./(1+epsilon_*abs(e_)) - error*input_vec/(input_vec.'*input_vec);
else
e_ = e_ - error*input_vec/(input_vec.'*input_vec);
end
end
e_dc = e_dc - obj.DCmu*error;
obj.error_log.e_ffe(cnt,trainloops) = e_ffe;
obj.error_log.e_dfe(cnt,trainloops) = e_dfe;
obj.error_log.e_(cnt,trainloops) = error;
cnt = cnt+1;
if obj.Nb(1) > 0
b_ = b_ + obj.DFEmu*error*reference_vec; % Seems like normalized DFE has worse performance
end
% figure(111);stem((e_),'Markersize',2);ylim([-1 1]);title('FFE Filter Taps');
%
% figure(222);
% stem(input_vec);ylim([-3 3]);
% hold on;
% stem(reference_vec);ylim([-3 3]);
% yline(error,'LineWidth',2); title('Input Vector');
% hold off
end
end
%%
% Plot the intermediate coefficients after training mode
obj.b = b_(1:obj.Nb(1));
obj.b2 = b_(obj.Nb(1)+1:obj.Nb(1)+Nb2);
obj.b3 = b_(obj.Nb(1)+Nb2+1:end);
obj.e = e_(1:obj.Ne(1));
obj.e2 = e_(obj.Ne(1)+1:obj.Ne(1)+N2);
obj.e3 = e_(obj.Ne(1)+N2+1:end);
if obj.plottrain
figure(8052)
sgtitle('Training Coeff')
subplot(2,3,1); stem((obj.e),'Markersize',2);
title('FFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,2); stem(obj.e2,'Markersize',2);
title('FFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,3); stem(obj.e3,'Markersize',2);
title('FFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,4);stem(obj.b,'Markersize',2);
title('DFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,5);stem(obj.b2,'Markersize',2);
title('DFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,6);stem(obj.b3,'Markersize',2);
title('DFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
%set(gcf,'Position',[200 500 700 400])
end
if obj.l1act
neg_lin = find(abs(obj.e) < obj.thres(1));
neg_2nd = find(abs(obj.e2) < obj.thres(2));
neg_3rd = find(abs(obj.e3) < obj.thres(3));
neg = [neg_lin;neg_2nd+obj.Ne(1);neg_3rd+obj.Ne(1)+N2]; % indices of the neglected coefficients
rel_lin = find(abs(obj.e) >= obj.thres(1));
rel_2nd = find(abs(obj.e2) >= obj.thres(2));
rel_3rd = find(abs(obj.e3) >= obj.thres(3));
obj.coeff_number = length(rel_lin)+2*length(rel_2nd)+3*length(rel_3rd);
rel = [rel_lin;rel_2nd+obj.Ne(1);rel_3rd+obj.Ne(1)+N2]; % indices of the relevant coefficients
e_(neg) = 0;
ind_mat_2nd(neg_2nd,:) = [];
ind_mat_3rd(neg_3rd,:) = [];
end
%% decision directed mode
if ~obj.DB_aim
constellation_in_ = unique(ref_in); % getting the symbol constellation from reference data
else
if obj.M == 2
constellation_in_ = [-3 -2 -1 0 1 2 3]/sqrt(5)*2;
elseif obj.M == 2.5
constellation_in_ = [-5 -4 -3 -2 -1 0 1 2 3 4 5]/sqrt(10)*2;
elseif obj.M == 3
constellation_in_ = [-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7]/sqrt(21)*2;
else
constellation_in_ = unique(ref_in);
end
end
obj.constellation_in = constellation_in_;
if obj.l1act
coeff = [e_(rel);b_]; % combine FFE and DFE coefficient vectors for DD mode
else
coeff = [e_;b_];
end
for dd_loop = 1:obj.dd_loops
cnt = 1;
m = 0;
output_vec = zeros(1,floor(length(data_in)/obj.K)); % initilaization of the output vector
dd_DFE = zeros(obj.Nb(1),1);
D_2 = zeros(Nb2,1);
D_3 = zeros(Nb3,1);
if all(obj.DDmu == obj.DDmu(1))
mu_mat = obj.DDmu(1);
else
if obj.l1act
mu_mat = diag([ones(1,length(rel_lin))*obj.DDmu(1) ones(1,length(rel_2nd))*obj.DDmu(2) ones(1,length(rel_3rd))*obj.DDmu(3) ones(1,obj.Nb)*obj.DDmu(4)]);
else
mu_mat = diag([ones(1,obj.Ne(1))*obj.DDmu(1) ones(1,N2)*obj.DDmu(2) ones(1,N3)*obj.DDmu(3) ones(1,obj.Nb(1)+Nb2+Nb3)*obj.DDmu(4)]);
end
end
if obj.load_decisions
pathn = evalin('base','modeldir');
temp = load([pathn, 'MLSE_out', '.mat']) ;
%eval(['dd_out_vals = temp.', 'a', ';']) ;
dd_out_vals=temp.a;
dd_out = zeros(size(data_in));
dd_out(1:2:length(data_in)) = dd_out_vals;
else
dd_out = zeros(size(data_in));
end
for k = 1:obj.K:length(data_in)
m=m+1; % Symbol index
X_1 = data(obj.Ne(1)+k-1:-1:k).';
[X_2,X_3] = obj.calc_nl_vecs(X_1,ind_mat_2nd,ind_mat_3rd,norm_fac2,norm_fac3,delta_2,delta_3,cplx);
if obj.l1act
input_vec = [X_1(rel_lin);X_2;X_3;-dd_DFE;-D_2;-D_3];
else
input_vec = [X_1;X_2;X_3;-dd_DFE;-D_2;-D_3];
end
output_vec(m) = e_dc + input_vec.'*coeff;
if ~obj.load_decisions
[~,dd_idx] = min(abs(output_vec(m) - constellation_in_)); % decision for closest constellation point
dd_out(k) = constellation_in_(dd_idx);
end
if obj.Nb(1) > 0
dd_DFE(2:end) = dd_DFE(1:end-1);
dd_DFE(1) = dd_out(k);
if obj.ideal_dfe && m > obj.k0
dd_DFE(1) = ref_in(m-obj.k0);
end
[D_2,D_3] = obj.calc_nl_vecs(dd_DFE,ind_mat_DFE_2nd,ind_mat_DFE_3rd,norm_fac_DFE2,norm_fac_DFE3,delta_DFE2,delta_DFE3,cplx);
end
% if dd_loop ~= 21
error = output_vec(m) - dd_out(k);
% else
% error = 0;
% end
coeff = coeff - mu_mat*error*conj(input_vec);
% e_save(:,save_ind) = coeff;
% save_ind = save_ind+1;
if 1%mu_mat ~= 0
e_dc = e_dc - obj.DCmu*error;
error_log(cnt,dd_loop) = e_dc;
cnt = cnt+1;
end
end
end
%figure(2023);plot(error_log(:,1))
% shifting the output sequence by k0 symbols
yout = (circshift(output_vec.',-(obj.k0))).'; %(circshift(dd_out.',-(obj.k0))).';
e_ = coeff(1:end-obj.Nb(1)-Nb2-Nb3);
b_ = coeff(end-obj.Nb(1)-Nb2-Nb3+1:end);
if obj.l1act
obj.e = e_(1:length(rel_lin));
obj.e2 = e_(length(rel_lin)+1:length(rel_lin)+length(rel_2nd));
obj.e3 = e_(length(rel_lin)+length(rel_2nd)+1:end);
else
obj.e = e_(1:obj.Ne(1));
obj.e2 = e_(obj.Ne(1)+1:obj.Ne(1)+N2);
obj.e3 = e_(obj.Ne(1)+N2+1:end);
end
obj.b = b_(1:obj.Nb(1));
obj.b2 = b_(obj.Nb(1)+1:obj.Nb(1)+Nb2);
obj.b3 = b_(obj.Nb(1)+Nb2+1:end);
% plot the final coefficients after DD mode
if obj.plotfinal
figure(8054)
if obj.l1act
sgtitle('Final Coeff')
subplot(2,3,1); stem(rel_lin,obj.e,'Markersize',2);
title('FFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,2); stem(rel_2nd,obj.e2,'Markersize',2);
title('FFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,3); stem(rel_3rd,obj.e3,'Markersize',2);
title('FFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,4);stem(obj.b,'Markersize',2);
title('DFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,5);stem(obj.b2,'Markersize',2);
title('DFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,6);stem(obj.b3,'Markersize',2);
title('DFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
else
sgtitle('Final Coeff')
subplot(2,3,1); stem(obj.e/max(e_),'Markersize',2);
title('FFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,2); stem(obj.e2,'Markersize',2);
title('FFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,3); stem(obj.e3,'Markersize',2);
title('FFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,4);stem(obj.b,'Markersize',2);
title('DFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,5);stem(obj.b2,'Markersize',2);
title('DFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,6);stem(obj.b3,'Markersize',2);
title('DFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
end
set(gcf,'Position',[1000 500 700 400])
end
% save frequency response to the work space
if obj.save_taps
% save the FFE coefficients to the work space
% pathn = evalin('base','modeldir');
% eval([obj.field_ffe, ' = obj.e ;']) ;
% eval([obj.field_dfe, ' = b ;']) ;
% eval(['save(''', pathn, '\',obj.filen,''', ''', obj.field_ffe,''', ''',obj.field_dfe,''') ;']) ;
save("coefficients",obj.e, obj.b);
end
else
yout = data_in;
end
end
function [X_2,X_3] = calc_nl_vecs(obj,X_1,ind_mat_2,ind_mat_3,norm_fac2,norm_fac3,delta_2,delta_3,cplx)
% calculation of the vectors containing all combinations of input symbols
% of second and third order based on the linear symbols
if ind_mat_2(1) > 0
input_vec_se = X_1(delta_2:end)/norm_fac2;%(K*(k0-1):end)
X_2 = input_vec_se(ind_mat_2(:,1)).*input_vec_se(ind_mat_2(:,2));
else
X_2 = [];
end
if ind_mat_3(1) > 0
if cplx
input_vec_th = X_1(delta_3:end)/norm_fac3;
X_3 = input_vec_th(ind_mat_3(:,1)).*input_vec_th(ind_mat_3(:,2)).*conj(input_vec_th(ind_mat_3(:,3)));
else
input_vec_th = X_1(delta_3:end)/norm_fac3;
X_3 = input_vec_th(ind_mat_3(:,1)).*input_vec_th(ind_mat_3(:,2)).*input_vec_th(ind_mat_3(:,3));
end
else
X_3 = [];
end
end
function [ind_mat_2nd,ind_mat_3rd] = calc_ind(obj,Ne2,N2,Ne3,N3,mode2nd,mode3rd,len_2nd,len_3rd,cplx)
if Ne2 > 0
ind_mat_2nd = NaN(N2,2);
count=1;
if mode2nd == 1
for t = 1:Ne2
for u = t:Ne2
ind_mat_2nd(count,:) = [t u];
count = count + 1 ;
end
end
elseif mode2nd == 2
for t = 1:Ne2
ind_mat_2nd(t,:) = [t t];
end
elseif mode2nd == 3
for t = 1:Ne2
for u = t:Ne2
if u-t<=len_2nd
ind_mat_2nd(count,:) = [t u];
count = count + 1 ;
end
end
end
elseif mode2nd == 4
for t = 1:Ne2
for u = t:Ne2
if u-t<=ceil(Ne2/2)
ind_mat_2nd(count,:) = [t u];
count = count + 1 ;
end
end
end
end
else
ind_mat_2nd = 0;
end
if Ne3 > 0
ind_mat_3rd = NaN(N3,3);
count=1;
if mode3rd == 1
if cplx
for t = 1:Ne3
for u = t:Ne3
for v = 1:Ne3
ind_mat_3rd(count,:) = [t u v];
count = count + 1 ;
end
end
end
else
for t = 1:Ne3
for u = t:Ne3
for v = u:Ne3
ind_mat_3rd(count,:) = [t u v];
count = count + 1 ;
end
end
end
end
elseif mode3rd == 2
for t = 1:Ne3
ind_mat_3rd(t,:) = [t t t];
end
elseif mode3rd == 3
for t = 1:Ne3
for u = t:Ne3
ind_mat_3rd(count,:) = [t t u];
if t ~= u
count = count + 1;
ind_mat_3rd(count,:) = [t u u];
end
count = count + 1;
end
end
elseif mode3rd == 4
for t = 1:Ne3
for u = t:Ne3
for v = u:Ne3
if u-t<=len_3rd && v-t<=len_3rd
ind_mat_3rd(count,:) = [t u v];
count = count + 1 ;
end
end
end
end
elseif mode3rd == 5
for t = 1:Ne3
for u = t:Ne3
if u-t<=len_3rd
ind_mat_3rd(count,:) = [t t u];
if t ~= u
count = count + 1;
ind_mat_3rd(count,:) = [t u u];
end
count = count + 1;
end
end
end
ind_mat_3rd2 = NaN(N3,3);
count = 1;
% for t = 1:Ne3
% ind_mat_3rd2(count,:) = [t t t];
% count = count + 1;
% end
for t = 1:Ne3
% ind_mat_3rd2(count,:) = [t t t];
% count = count + 1;
for u = t:min(Ne3,t+len_3rd)
for v = unique([t u])
ind_mat_3rd2(count,:) = [t v u];
count = count + 1;
% ind_mat_3rd2(count,:) = [t u u];
% count = count + 1;
end
end
end
end
else
ind_mat_3rd = 0;
end
end
function [ind_mat_2nd,ind_mat_3rd] = calc_DFE_ind(obj,Ne2,N2,Ne3,N3)
if Ne2 > 0
ind_mat_2nd = NaN(N2,2);
count=1;
for t = 1:Ne2
for u = t:Ne2
ind_mat_2nd(count,:) = [t u];
count = count + 1 ;
end
end
else
ind_mat_2nd = 0;
end
if Ne3 > 0
ind_mat_3rd = NaN(N3,3);
count=1;
for t = 1:Ne3
for u = t:Ne3
for v = u:Ne3
ind_mat_3rd(count,:) = [t u v];
count = count + 1 ;
end
end
end
else
ind_mat_3rd = 0;
end
end
end
end

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@@ -0,0 +1,727 @@
classdef EQ_copy
%EQ Summary of this class goes here
% Detailed explanation goes here
properties
Ne %Number of feed forward coefficients (1st, 2nd and 3rd order)
Nb %Number of decision feedback coefficients (1st, 2nd and 3rd order)
K %Number of samples per symbol
delay %Delay of incoming signal
training_length %Number of training symbols
training_loops %Number of loops through sequence for training mode
ideal_dfe %Error free DFE decisions
DB_aim %Aim at duobinary output sequence
M %Order of the PAM constellation (only relevant in case of DB aim)
FFEmu %mu parameter for FFE part in training mode (0 means normalized LMS)
DFEmu % mu parameter for DFE part in training mode
dd_loops % Number of loops through sequence for DD mode
DDmu % mu parameters for DD mode (individual value for each order)
DCmu % mu parameter for the dc tap
l1act %Activate/deactive l1 regularization
rho %Parameter for speed of coeff shrinking
epsilon %Reciprocal value of the magnitude of the coeff to converge to zero (1st,2nd,3rd order)
thres %Theshold for neglecting coefficienties (1st,2nd,3rd order)
static_act %Activate/deactive static coefficient reduction
mode2nd %0: no reduction | 1: polynomial | 2: restricted to interval
len_2nd %length of the interval (only for 2nd order mode = 2)
mode3rd %0: no reduction | 1: polynomial | 2: restricted to interval
len_3rd %length of the interval (only for 3rd order mode = 3/4)
plottrain
plotfinal
load_decisions
save_taps
%during simulation
k0
b
b2
b3
e
e2
e3
coeff_number
constellation_in
end
methods
function obj = EQ_copy(options)
%EQ Construct an instance of this class
% Detailed explanation goes here
arguments(Input)
options.Ne = [10 0 0] %Number of feed forward coefficients (1st, 2nd and 3rd order)
options.Nb = [10 0 0]%Number of decision feedback coefficients (1st, 2nd and 3rd order)
options.K = 1 %Number of samples per symbol
options.delay = 0 %Delay of incoming signal
options.training_length = 1024 %Number of training symbols
options.training_loops = 1 %Number of loops through sequence for training mode
options.ideal_dfe = 0 %Error free DFE decisions
options.DB_aim %Aim at duobinary output sequence
options.M = 1 %Order of the PAM constellation (only relevant in case of DB aim)
options.FFEmu = 0 %mu parameter for FFE part in training mode (0 means normalized LMS)
options.DFEmu = 0.005 % mu parameter for DFE part in training mode
options.dd_loops = 1% Number of loops through sequence for DD mode
options.DDmu = [0.0004 0.0004 0.0004 0.0004 ] % mu parameters for DD mode (individual value for each order)
options.DCmu = 0.005 % mu parameter for the dc tap
options.l1act = 0 %Activate/deactive l1 regularization
options.rho = 5e-4%Parameter for speed of coeff shrinking
options.epsilon = [10 100 1000] %Reciprocal value of the magnitude of the coeff to converge to zero (1st,2nd,3rd order)
options.thres = [5e-3 4e-3 5e-4]%Theshold for neglecting coefficienties (1st,2nd,3rd order)
options.static_act = 0 %Activate/deactive static coefficient reduction
options.mode2nd = 1%0: no reduction | 1: polynomial | 2: restricted to interval
options.len_2nd = 1 %length of the interval (only for 2nd order mode = 2)
options.mode3rd = 1%0: no reduction | 1: polynomial | 2: restricted to interval
options.len_3rd = 1%length of the interval (only for 3rd order mode = 3/4)
options.plottrain = 0
options.plotfinal = 0
options.load_decisions = 0
options.save_taps = 0
end
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
end
function [signalclass_out,error_log] = process(obj,signalclass_in, reference_signalclass_in)
% actual processing of the signal (steps 1. - 3.)
[signalclass_in.signal,error_log] = obj.process_(signalclass_in.signal', reference_signalclass_in.signal');
signalclass_in.signal = signalclass_in.signal';
% append to logbook
lbdesc = ['EQ '];
signalclass_in = signalclass_in.logbookentry(lbdesc);
% write to output
signalclass_out = signalclass_in;
end
function [yout,error_log] = process_(obj,data_in,ref_in)
%METHOD1 Summary of this method goes here
% Detailed explanation goes here
if obj.DB_aim
ref_DB = zeros(size(ref_in));
for k = 1:length(ref_in)
if k == 1
ref_DB(k) = ref_in(k);
else
ref_DB(k) = ref_in(k) + ref_in(k-1);
end
end
ref_in = ref_DB;
end
ref = [zeros(1,obj.Nb(1)-1) ref_in zeros(1,obj.Nb(1))];
if isreal(ref)
cplx = 0;
else
cplx = 1;
end
if obj.static_act
obj.mode2nd = obj.mode2nd + 1;
obj.mode3rd = obj.mode3rd + 1;
else
obj.mode2nd = 1;
obj.mode3rd = 1;
end
if obj.mode2nd == 1
N2 = (obj.Ne(2)*(obj.Ne(2)+1))/2; % Number of coefficients for second order
elseif obj.mode2nd == 2
N2 = obj.Ne(2);
elseif obj.mode2nd == 3
N2 = (obj.len_2nd+1)*(2*obj.Ne(2)-obj.len_2nd)/2;
elseif obj.mode2nd == 4
N2 = (ceil(obj.Ne(2)/2)+1)*(2*obj.Ne(2)-ceil(obj.Ne(2)/2))/2;
end
if obj.mode3rd == 1
if cplx
N3 = obj.Ne(3)^2*(obj.Ne(3)+1)/2;
else
N3 = obj.Ne(3)*(obj.Ne(3)+1)*(obj.Ne(3)+2)/6; % Number of coefficients for third order
end
elseif obj.mode3rd == 2
N3 = obj.Ne(3);
elseif obj.mode3rd == 3
N3 = obj.Ne(3)^2;
elseif obj.mode3rd == 4
N3 = round(1/6*(obj.len_3rd+1)*(obj.len_3rd+2)*(3*obj.Ne(3)-2*obj.len_3rd));
elseif obj.mode3rd == 5
N3 = 2*obj.Ne(3)*obj.len_3rd-obj.len_3rd*(obj.len_3rd+1)+obj.Ne(3);
end
Nb2 = (obj.Nb(2)*(obj.Nb(2)+1))/2;
Nb3 = obj.Nb(3)*(obj.Nb(3)+1)*(obj.Nb(3)+2)/6;
data_in = data_in/sqrt(mean(abs(data_in).^2)); % power normalization of input sequence
if obj.FFEmu == 0
norm_fac2 = sqrt(mean(abs(data_in.^2).^2)); % power normalization for second and third order terms
norm_fac3 = sqrt(mean(abs(data_in.^3).^2)); % (not necessary, but seems to be more stable if applied --> same as different mu values for linear and nl terms)
else
norm_fac2 = 1;
norm_fac3 = 1;
end
norm_fac_DFE2 = sqrt(mean(abs(ref_in.^2).^2)); % same for DFE input (reference)
norm_fac_DFE3 = sqrt(mean(abs(ref_in.^3).^2));
data = [zeros(1,floor(obj.Ne(1)/2)) data_in zeros(1,obj.Ne(1))];
delta_2 = round((obj.Ne(1)-obj.Ne(2))/2);
delta_3 = round((obj.Ne(1)-obj.Ne(3))/2);
delta_DFE2 = 1;%round((obj.Nb-obj.Nb(2))/2);
delta_DFE3 = 1;%round((obj.Nb-obj.Nb(3))/2);
% calculate the indices for the combination of second and third order symbols
% - done in advance because it's the same for each iteration, so time
% can be saved
[ind_mat_2nd,ind_mat_3rd] = obj.calc_ind(obj.Ne(2),N2,obj.Ne(3),N3,obj.mode2nd,obj.mode3rd,obj.len_2nd,obj.len_3rd,cplx);
[ind_mat_DFE_2nd,ind_mat_DFE_3rd] = obj.calc_DFE_ind(obj.Nb(2),Nb2,obj.Nb(3),Nb3);
if obj.l1act
epsilon_ = diag([ones(1,obj.Ne(1))*obj.epsilon(1) ones(1,N2)*obj.epsilon(2) ones(1,N3)*obj.epsilon(3)]);
end
obj.k0 = obj.delay; % input delay compared to training sequence
error_log = [];
if 1 % obj.active
%% Calculation of the filter coefficients in training based LMS mode
e_ = zeros(obj.Ne(1)+N2+N3,1); % initialization of filter coefficients
b_ = zeros(obj.Nb(1)+Nb2+Nb3,1);
e_dc = mean(data_in); % initilaization of the dc tap with the mean value of the whole data
for trainloops = 1:obj.training_loops
cnt = 1;
m = obj.k0+1; % starting symbol index at the delay compared to the training sequence
% n => index in rx data sequence
%Step From: Oversampling(=2) * Startdelay + 1
%Step Width: Oversampling(=2)
%Step To: Oversampling(=2) * Training Length
for n = obj.K*obj.k0+1:obj.K:obj.K*obj.training_length
% m => index in reference sequence
m = m+1;
%
%dc_ = mean(data(obj.Ne(1)+n+(obj.K-1):-1:n+obj.K).');
% cut symbols from rx data sequence
X_1 = data(obj.Ne(1)+n+(obj.K-1):-1:n+obj.K).';
[X_2,X_3] = obj.calc_nl_vecs(X_1,ind_mat_2nd,ind_mat_3rd,norm_fac2,norm_fac3,delta_2,delta_3,cplx);
input_vec = [X_1;X_2;X_3];
% cut symbols from desired data sequence (correct symbols in training mode)
D_1 = ref(obj.Nb(1)-obj.k0+m-2:-1:m-obj.k0-1).';
[D_2,D_3] = obj.calc_nl_vecs(D_1,ind_mat_DFE_2nd,ind_mat_DFE_3rd,norm_fac_DFE2,norm_fac_DFE3,delta_DFE2,delta_DFE3,cplx);
reference_vec = [D_1;D_2;D_3];
e_ffe = e_.'*input_vec;
e_dfe = b_.'*reference_vec;
error = e_dc + e_ffe - e_dfe - ref_in(m-obj.k0);
%error = e_dc + e_.'*input_vec - b_.'*reference_vec - ref_in(m-obj.k0);
if real(obj.FFEmu)
if obj.l1act
sgn_e = e_;
sgn_e(e_~=0) = e_(e_~=0)./abs(e_(e_~=0));
e_ = e_ - obj.rho*sgn_e./(1+epsilon_*abs(e_)) - error*input_vec*obj.FFEmu;
else
e_ = e_ - error*conj(input_vec)*obj.FFEmu; %classic LMS gradient decay
end
else
if obj.l1act
sgn_e = e_;
sgn_e(e_~=0) = e_(e_~=0)./abs(e_(e_~=0));
e_ = e_ - obj.rho*sgn_e./(1+epsilon_*abs(e_)) - error*input_vec/(input_vec.'*input_vec);
else
e_ = e_ - error*input_vec/(input_vec.'*input_vec);
end
end
e_dc = e_dc - obj.DCmu*error;
error_log(cnt,trainloops) = error;
cnt = cnt+1;
if obj.Nb(1) > 0
b_ = b_ + obj.DFEmu*error*reference_vec; % Seems like normalized DFE has worse performance
end
% figure(111);stem((e_),'Markersize',2);ylim([-1 1]);title('FFE Filter Taps');
%
% figure(222);
% stem(input_vec);ylim([-3 3]);
% hold on;
% stem(reference_vec);ylim([-3 3]);
% yline(error,'LineWidth',2); title('Input Vector');
% hold off
end
end
%%
% Plot the intermediate coefficients after training mode
obj.b = b_(1:obj.Nb(1));
obj.b2 = b_(obj.Nb(1)+1:obj.Nb(1)+Nb2);
obj.b3 = b_(obj.Nb(1)+Nb2+1:end);
obj.e = e_(1:obj.Ne(1));
obj.e2 = e_(obj.Ne(1)+1:obj.Ne(1)+N2);
obj.e3 = e_(obj.Ne(1)+N2+1:end);
if obj.plottrain
figure(8052)
sgtitle('Training Coeff')
subplot(2,3,1); stem((obj.e),'Markersize',2);
title('FFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,2); stem(obj.e2,'Markersize',2);
title('FFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,3); stem(obj.e3,'Markersize',2);
title('FFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,4);stem(obj.b,'Markersize',2);
title('DFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,5);stem(obj.b2,'Markersize',2);
title('DFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,6);stem(obj.b3,'Markersize',2);
title('DFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
%set(gcf,'Position',[200 500 700 400])
end
if obj.l1act
neg_lin = find(abs(obj.e) < obj.thres(1));
neg_2nd = find(abs(obj.e2) < obj.thres(2));
neg_3rd = find(abs(obj.e3) < obj.thres(3));
neg = [neg_lin;neg_2nd+obj.Ne(1);neg_3rd+obj.Ne(1)+N2]; % indices of the neglected coefficients
rel_lin = find(abs(obj.e) >= obj.thres(1));
rel_2nd = find(abs(obj.e2) >= obj.thres(2));
rel_3rd = find(abs(obj.e3) >= obj.thres(3));
obj.coeff_number = length(rel_lin)+2*length(rel_2nd)+3*length(rel_3rd);
rel = [rel_lin;rel_2nd+obj.Ne(1);rel_3rd+obj.Ne(1)+N2]; % indices of the relevant coefficients
e_(neg) = 0;
ind_mat_2nd(neg_2nd,:) = [];
ind_mat_3rd(neg_3rd,:) = [];
end
%% decision directed mode
if ~obj.DB_aim
constellation_in_ = unique(ref_in); % getting the symbol constellation from reference data
else
if obj.M == 2
constellation_in_ = [-3 -2 -1 0 1 2 3]/sqrt(5)*2;
elseif obj.M == 2.5
constellation_in_ = [-5 -4 -3 -2 -1 0 1 2 3 4 5]/sqrt(10)*2;
elseif obj.M == 3
constellation_in_ = [-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7]/sqrt(21)*2;
else
constellation_in_ = unique(ref_in);
end
end
obj.constellation_in = constellation_in_;
if obj.l1act
coeff = [e_(rel);b_]; % combine FFE and DFE coefficient vectors for DD mode
else
coeff = [e_;b_];
end
for dd_loop = 1:obj.dd_loops
cnt = obj.training_length+1;
m = 0;
output_vec = zeros(1,floor(length(data_in)/obj.K)); % initilaization of the output vector
dd_DFE = zeros(obj.Nb(1),1);
D_2 = zeros(Nb2,1);
D_3 = zeros(Nb3,1);
if all(obj.DDmu == obj.DDmu(1))
mu_mat = obj.DDmu(1);
else
if obj.l1act
mu_mat = diag([ones(1,length(rel_lin))*obj.DDmu(1) ones(1,length(rel_2nd))*obj.DDmu(2) ones(1,length(rel_3rd))*obj.DDmu(3) ones(1,obj.Nb)*obj.DDmu(4)]);
else
mu_mat = diag([ones(1,obj.Ne(1))*obj.DDmu(1) ones(1,N2)*obj.DDmu(2) ones(1,N3)*obj.DDmu(3) ones(1,obj.Nb(1)+Nb2+Nb3)*obj.DDmu(4)]);
end
end
if obj.load_decisions
pathn = evalin('base','modeldir');
temp = load([pathn, 'MLSE_out', '.mat']) ;
%eval(['dd_out_vals = temp.', 'a', ';']) ;
dd_out_vals=temp.a;
dd_out = zeros(size(data_in));
dd_out(1:2:length(data_in)) = dd_out_vals;
else
dd_out = zeros(size(data_in));
end
for k = 1:obj.K:length(data_in)
m=m+1; % Symbol index
X_1 = data(obj.Ne(1)+k-1:-1:k).';
[X_2,X_3] = obj.calc_nl_vecs(X_1,ind_mat_2nd,ind_mat_3rd,norm_fac2,norm_fac3,delta_2,delta_3,cplx);
if obj.l1act
input_vec = [X_1(rel_lin);X_2;X_3;-dd_DFE;-D_2;-D_3];
else
input_vec = [X_1;X_2;X_3;-dd_DFE;-D_2;-D_3];
end
output_vec(m) = e_dc + input_vec.'*coeff;
if ~obj.load_decisions
[~,dd_idx] = min(abs(output_vec(m) - constellation_in_)); % decision for closest constellation point
dd_out(k) = constellation_in_(dd_idx);
end
if obj.Nb(1) > 0
dd_DFE(2:end) = dd_DFE(1:end-1);
dd_DFE(1) = dd_out(k);
if obj.ideal_dfe && m > obj.k0
dd_DFE(1) = ref_in(m-obj.k0);
end
[D_2,D_3] = obj.calc_nl_vecs(dd_DFE,ind_mat_DFE_2nd,ind_mat_DFE_3rd,norm_fac_DFE2,norm_fac_DFE3,delta_DFE2,delta_DFE3,cplx);
end
% if dd_loop ~= 21
error = output_vec(m) - dd_out(k);
% else
% error = 0;
% end
coeff = coeff - mu_mat*error*conj(input_vec);
% e_save(:,save_ind) = coeff;
% save_ind = save_ind+1;
if mu_mat ~= 0
e_dc = e_dc - obj.DCmu*error;
error_log(cnt,dd_loop) = error;
cnt = cnt+1;
end
end
end
%figure(2023);plot(error_log(:,1))
% shifting the output sequence by k0 symbols
yout = (circshift(output_vec.',-(obj.k0))).'; %(circshift(dd_out.',-(obj.k0))).';
e_ = coeff(1:end-obj.Nb(1)-Nb2-Nb3);
b_ = coeff(end-obj.Nb(1)-Nb2-Nb3+1:end);
if obj.l1act
obj.e = e_(1:length(rel_lin));
obj.e2 = e_(length(rel_lin)+1:length(rel_lin)+length(rel_2nd));
obj.e3 = e_(length(rel_lin)+length(rel_2nd)+1:end);
else
obj.e = e_(1:obj.Ne(1));
obj.e2 = e_(obj.Ne(1)+1:obj.Ne(1)+N2);
obj.e3 = e_(obj.Ne(1)+N2+1:end);
end
obj.b = b_(1:obj.Nb(1));
obj.b2 = b_(obj.Nb(1)+1:obj.Nb(1)+Nb2);
obj.b3 = b_(obj.Nb(1)+Nb2+1:end);
% plot the final coefficients after DD mode
if obj.plotfinal
figure(8054)
if obj.l1act
sgtitle('Final Coeff')
subplot(2,3,1); stem(rel_lin,obj.e,'Markersize',2);
title('FFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,2); stem(rel_2nd,obj.e2,'Markersize',2);
title('FFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,3); stem(rel_3rd,obj.e3,'Markersize',2);
title('FFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,4);stem(obj.b,'Markersize',2);
title('DFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,5);stem(obj.b2,'Markersize',2);
title('DFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,6);stem(obj.b3,'Markersize',2);
title('DFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
else
sgtitle('Final Coeff')
subplot(2,3,1); stem(obj.e/max(e_),'Markersize',2);
title('FFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,2); stem(obj.e2,'Markersize',2);
title('FFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,3); stem(obj.e3,'Markersize',2);
title('FFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,4);stem(obj.b,'Markersize',2);
title('DFE coeff linear')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,5);stem(obj.b2,'Markersize',2);
title('DFE coeff nl 2nd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
subplot(2,3,6);stem(obj.b3,'Markersize',2);
title('DFE coeff nl 3rd')
xlabel('coefficient index'); ylabel('value'); set(gca,'Fontsize',12)
end
set(gcf,'Position',[1000 500 700 400])
end
% save frequency response to the work space
if obj.save_taps
% save the FFE coefficients to the work space
% pathn = evalin('base','modeldir');
% eval([obj.field_ffe, ' = obj.e ;']) ;
% eval([obj.field_dfe, ' = b ;']) ;
% eval(['save(''', pathn, '\',obj.filen,''', ''', obj.field_ffe,''', ''',obj.field_dfe,''') ;']) ;
save("coefficients",obj.e, obj.b);
end
else
yout = data_in;
end
end
function [X_2,X_3] = calc_nl_vecs(obj,X_1,ind_mat_2,ind_mat_3,norm_fac2,norm_fac3,delta_2,delta_3,cplx)
% calculation of the vectors containing all combinations of input symbols
% of second and third order based on the linear symbols
if ind_mat_2(1) > 0
input_vec_se = X_1(delta_2:end)/norm_fac2;%(K*(k0-1):end)
X_2 = input_vec_se(ind_mat_2(:,1)).*input_vec_se(ind_mat_2(:,2));
else
X_2 = [];
end
if ind_mat_3(1) > 0
if cplx
input_vec_th = X_1(delta_3:end)/norm_fac3;
X_3 = input_vec_th(ind_mat_3(:,1)).*input_vec_th(ind_mat_3(:,2)).*conj(input_vec_th(ind_mat_3(:,3)));
else
input_vec_th = X_1(delta_3:end)/norm_fac3;
X_3 = input_vec_th(ind_mat_3(:,1)).*input_vec_th(ind_mat_3(:,2)).*input_vec_th(ind_mat_3(:,3));
end
else
X_3 = [];
end
end
function [ind_mat_2nd,ind_mat_3rd] = calc_ind(obj,Ne2,N2,Ne3,N3,mode2nd,mode3rd,len_2nd,len_3rd,cplx)
if Ne2 > 0
ind_mat_2nd = NaN(N2,2);
count=1;
if mode2nd == 1
for t = 1:Ne2
for u = t:Ne2
ind_mat_2nd(count,:) = [t u];
count = count + 1 ;
end
end
elseif mode2nd == 2
for t = 1:Ne2
ind_mat_2nd(t,:) = [t t];
end
elseif mode2nd == 3
for t = 1:Ne2
for u = t:Ne2
if u-t<=len_2nd
ind_mat_2nd(count,:) = [t u];
count = count + 1 ;
end
end
end
elseif mode2nd == 4
for t = 1:Ne2
for u = t:Ne2
if u-t<=ceil(Ne2/2)
ind_mat_2nd(count,:) = [t u];
count = count + 1 ;
end
end
end
end
else
ind_mat_2nd = 0;
end
if Ne3 > 0
ind_mat_3rd = NaN(N3,3);
count=1;
if mode3rd == 1
if cplx
for t = 1:Ne3
for u = t:Ne3
for v = 1:Ne3
ind_mat_3rd(count,:) = [t u v];
count = count + 1 ;
end
end
end
else
for t = 1:Ne3
for u = t:Ne3
for v = u:Ne3
ind_mat_3rd(count,:) = [t u v];
count = count + 1 ;
end
end
end
end
elseif mode3rd == 2
for t = 1:Ne3
ind_mat_3rd(t,:) = [t t t];
end
elseif mode3rd == 3
for t = 1:Ne3
for u = t:Ne3
ind_mat_3rd(count,:) = [t t u];
if t ~= u
count = count + 1;
ind_mat_3rd(count,:) = [t u u];
end
count = count + 1;
end
end
elseif mode3rd == 4
for t = 1:Ne3
for u = t:Ne3
for v = u:Ne3
if u-t<=len_3rd && v-t<=len_3rd
ind_mat_3rd(count,:) = [t u v];
count = count + 1 ;
end
end
end
end
elseif mode3rd == 5
for t = 1:Ne3
for u = t:Ne3
if u-t<=len_3rd
ind_mat_3rd(count,:) = [t t u];
if t ~= u
count = count + 1;
ind_mat_3rd(count,:) = [t u u];
end
count = count + 1;
end
end
end
ind_mat_3rd2 = NaN(N3,3);
count = 1;
% for t = 1:Ne3
% ind_mat_3rd2(count,:) = [t t t];
% count = count + 1;
% end
for t = 1:Ne3
% ind_mat_3rd2(count,:) = [t t t];
% count = count + 1;
for u = t:min(Ne3,t+len_3rd)
for v = unique([t u])
ind_mat_3rd2(count,:) = [t v u];
count = count + 1;
% ind_mat_3rd2(count,:) = [t u u];
% count = count + 1;
end
end
end
end
else
ind_mat_3rd = 0;
end
end
function [ind_mat_2nd,ind_mat_3rd] = calc_DFE_ind(obj,Ne2,N2,Ne3,N3)
if Ne2 > 0
ind_mat_2nd = NaN(N2,2);
count=1;
for t = 1:Ne2
for u = t:Ne2
ind_mat_2nd(count,:) = [t u];
count = count + 1 ;
end
end
else
ind_mat_2nd = 0;
end
if Ne3 > 0
ind_mat_3rd = NaN(N3,3);
count=1;
for t = 1:Ne3
for u = t:Ne3
for v = u:Ne3
ind_mat_3rd(count,:) = [t u v];
count = count + 1 ;
end
end
end
else
ind_mat_3rd = 0;
end
end
end
end

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classdef EQ_silas < handle
%EQ_SILAS FFE and DFE Equalizer Playground
properties
% Important Signals
x_in %Input Sequence to be equalized
x_length
x_norm
d %reference signal
d_norm
d_constellation %constellation points of the reference
y_out %equalizer output signal
d_out %decision output
% FFE coefficients always named with "e"
Ne
Ce %memory length FFE
Ie1 %Indice Combination of 1nd order FFE
Ie2 %Indice Combination of 2nd order FFE
Ie3 %Indice Combination of 3nd order FFE
e %coefficients for FFE
% DFE coefficients always named with "b"
Nb
Cb %memory length DFE
Ib1 %Indice Combination of 1nd order DFE
Ib2 %Indice Combination of 2nd order DFE
Ib3 %Indice Combination of 3nd order DFE
b %coefficients for DFE
error
e_ffe
e_dfe
e_dc
% coefficients
mu_dc_train
mu_ffe_train
mu_dfe_train
mu_dc_dd
mu_ffe_dd
mu_dfe_dd
mu_combined_dd % [1st order FFE, 2nd order FFE, 3rd order FFE, all orders DFE]
delay
trainlength
sps
trainloops
ddloops
eq_parallelization_blocklength % block lengt of EQ (until now, only the dc subtraction is affected by this)
eq_updatelatency % time in symbols until the calculated updates reach the signal again (until now, only the dc subtraction is affected by this)
eq_avg_blocklength
end
methods
function obj = EQ_silas(options)
%EQ_SILAS Construct an instance of this class
arguments(Input)
options.Ne = [50 5 0] %Number of FFE coefficients (1st, 2nd and 3rd order)
options.Nb = [30 5 3] %Number of DFE coefficients (1st, 2nd and 3rd order)
options.trainloops = 2;
options.trainlength = 4096;
options.ddloops = 2;
options.delay = 0;
options.sps = 2;
options.mu_dc_train = 0.01;
options.mu_ffe_train = 0.005;
options.mu_dfe_train = 0.005;
options.mu_dc_dd = 0.01;
options.mu_ffe_dd = [0.0004 0.0005 0.0006];
options.mu_dfe_dd = 0.0005;
options.eq_parallelization_blocklength = 1;
options.eq_updatelatency = 1;
options.eq_avg_blocklength = 0;
end
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
% Generate helpful vectors and initialize the filters with
% correct length:
obj.Ce = obj.calcVNLEMemoryLength(obj.Ne);
[obj.Ie2,obj.Ie3] = obj.calcIndiceVectors(obj.Ne);
obj.e = zeros(sum(obj.Ce),1);
obj.Cb = obj.calcVNLEMemoryLength(obj.Nb);
[obj.Ib2,obj.Ib3] = obj.calcIndiceVectors(obj.Nb);
obj.b = zeros(sum(obj.Cb),1);
end
function [signalclass_out,symbols_out] = process(obj,signalclass_in, reference_signalclass_in)
% actual processing of the signal (steps 1. - 3.)
% 1 normalize RMS
signalclass_in = signalclass_in.normalize("mode","rms");
% Process the EQ optimization
obj.process_(signalclass_in.signal', reference_signalclass_in.signal');
signalclass_in.signal = obj.y_out';
%change sampling frequency of outgoing signal
signalclass_in.fs = reference_signalclass_in.fs;
% append to logbook
lbdesc = ['EQ von Silas ist gelaufen '];
signalclass_in = signalclass_in.logbookentry(lbdesc);
symbols_out = signalclass_in;
symbols_out.signal = obj.d_out;
% write to output
signalclass_out = signalclass_in;
end
function process_(obj,x_in,d_in)
% 1) prepare signals
obj.e_dc = mean(x_in);
% 1.1) Input Signal
obj.x_in = [zeros(1,floor(obj.Ne(1)/2)) x_in zeros(1,obj.Ne(1))];
obj.x_length = length(x_in);
obj.x_norm = obj.calcPowerNormalization(x_in);
% 1.2 Reference Signal // Constellation
obj.d = [zeros(1,obj.Nb(1)-1) d_in zeros(1,obj.Nb(1))];
obj.d_constellation = unique(d_in);
obj.d_norm = obj.calcPowerNormalization(d_in);
% 1.3 Training
obj.trainingMode();
% 1.4 Decision Directed Mode
obj.decisionDirectedMode();
end
%% Adaptive Equalization Modes
function trainingMode(obj)
dc_block = ones(obj.eq_parallelization_blocklength,1);
for tloop = 1:obj.trainloops
m = 1+obj.delay;
dc_cnt = 0;
for n = obj.sps*obj.delay+1:obj.sps:obj.sps*obj.trainlength
m = m+1;
dc_cnt = dc_cnt+1;
%get Sigal input vectors with correct length for VNLE
x_in_block = obj.x_in(obj.Ne(1)+n+(obj.sps-1):-1:n+obj.sps).';
x_in_vnle_format = obj.calcVNLENonlinVecs(x_in_block,obj.Ie2,obj.Ie3,obj.Ne,obj.x_norm);
%get Reference input vectors with correct length for VNLE
d_block = obj.d(obj.Nb(1)-obj.delay+m-2:-1:m-obj.delay-1).';
d_vnle_format = obj.calcVNLENonlinVecs(d_block,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
obj.e_ffe = obj.e.' * x_in_vnle_format;
obj.e_dfe = obj.b.' * d_vnle_format;
% Calculate the Error
obj.error = obj.e_dc + obj.e_ffe - obj.e_dfe - obj.d(obj.Nb(1)-1+m-obj.delay);
if obj.mu_ffe_train ~= 0
%update FFE coefficients with LMS
obj.e = obj.e - obj.error*conj(x_in_vnle_format)*obj.mu_ffe_train;
else
%update FFE coefficients with NLMS
obj.e = obj.e - obj.error*x_in_vnle_format/(x_in_vnle_format.'*x_in_vnle_format);
end
%update DFE coefficients with LMS
obj.b = obj.b + obj.mu_dfe_train*obj.error*d_vnle_format;
%update DC error
dc_block(dc_cnt) = obj.error .* obj.mu_dc_train;
if dc_cnt == obj.eq_parallelization_blocklength
obj.e_dc = obj.e_dc - mean(dc_block(dc_cnt));
dc_cnt = 0;
end
end
end
end
function decisionDirectedMode(obj)
%start the dd mode with coefficients from training
coeff = [obj.e;obj.b];
obj.e_dc = ones(obj.eq_updatelatency,1).*obj.e_dc;
dc_block = ones(obj.eq_parallelization_blocklength,1);
for ddloop = 1:obj.ddloops
m = 0;
dc_cnt = 0;
mu_mat = diag([ones(1,obj.Ce(1))*obj.mu_ffe_dd(1)... %1st order ffe
ones(1,obj.Ce(2))*obj.mu_ffe_dd(2)... %2nd order ffe
ones(1,obj.Ce(3))*obj.mu_ffe_dd(3)... %3rd order ffe
ones(1,sum(obj.Cb))*obj.mu_dfe_dd]); %all order dfe
y = zeros(1,floor(obj.x_length/obj.sps));
d_feedback = zeros(obj.Cb(1),1);
d_vnle = obj.calcVNLENonlinVecs(d_feedback,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
d_hat = NaN(length(obj.d),numel(obj.d_constellation));
lvl_err_1 = NaN(length(obj.d),numel(obj.d_constellation));
lvl_err_2 = NaN(length(obj.d),numel(obj.d_constellation));
subtracted_error =NaN(length(obj.d),numel(obj.d_constellation));
y_1= NaN(length(obj.d),numel(obj.d_constellation));
y_2= NaN(length(obj.d),numel(obj.d_constellation));
lvl_err_mov = NaN(obj.eq_avg_blocklength,numel(obj.d_constellation));
m_reg = 0;
for k = 1:obj.sps:obj.x_length
dc_cnt = dc_cnt+1;
m=m+1;
%get Sigal input vectors with correct length for VNLE
x = obj.x_in(obj.Ne(1)+k-1:-1:k).';
%bring this signal to "special" VNLE format
x_vnle = obj.calcVNLENonlinVecs(x,obj.Ie2,obj.Ie3,obj.Ne,obj.x_norm);
%combine FFE with DFE to one vector (cursor between the two sequences)
x_d = [x_vnle;-d_vnle];
%Apply filter
y(m) = x_d.'* coeff;
%Decision 1
[~,symbol_idx] = min(abs(y(m) - obj.d_constellation)); % decision for closest constellation point
d_hat(m,symbol_idx) = obj.d_constellation(symbol_idx);
y_1(m,symbol_idx) = y(m); % after 1st iteration
%1st Error between FFE & DFE filtered signal and Decision
obj.error(m) = y(m) - d_hat(m,symbol_idx);
% lvl_err_1(m,symbol_idx) = y(m) - obj.d(m+1);
%
% %write current error to buffer
% lvl_err_mov(:,symbol_idx) = circshift(lvl_err_mov(:,symbol_idx),1);
% lvl_err_mov(1,symbol_idx) = obj.error(m);
%
% %Subtract a weighted error from y -> then Decision 2
% err = mean(lvl_err_mov(:,symbol_idx),'omitnan');
%
% y(m) = y(m)-(obj.mu_dc_dd(symbol_idx)*err);
%
% subtracted_error(m,symbol_idx) = obj.mu_dc_dd(symbol_idx)*mean(lvl_err_mov(:,symbol_idx),'omitnan');
%
% y_2(m,symbol_idx) = y(m);
%
% [~,symbol_idx] = min(abs(y(m) - obj.d_constellation)); % decision 2 for closest constellation point
%
% d_hat(m,symbol_idx) = obj.d_constellation(symbol_idx);
%
% obj.error(m) = y(m) - d_hat(m,symbol_idx);
%
% lvl_err_2(m,symbol_idx) = y(m) - obj.d(m+1);
%Update FFE and DFE coefficients
coeff = coeff - (mu_mat * (obj.error(m) * conj(x_d)));
% Append new decision to decision feedback
if obj.Nb(1) > 0
%shift up one index
d_feedback(2:end) = d_feedback(1:end-1);
%replace 1st index with current estimation
d_feedback(1) = d_hat(m,symbol_idx);
%build memorylike VNLE version
d_vnle = obj.calcVNLENonlinVecs(d_feedback,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
end
end
end
%%
obj.y_out = (circshift( y.' ,-(obj.delay))).';
obj.d_out = d_hat(1:2:end);
% evm1 = mean(lvl_err_1,'omitnan');
%
% evm2 = mean(lvl_err_2,'omitnan');
%
% figure(112)
% stem(evm1,'LineStyle','--','Marker','square','LineWidth',1);
% hold on;
% stem(evm2,'LineStyle',':','Marker','v','LineWidth',1);
% figure(14)
% scatter(1:length(lvl_err_1),subtracted_error,1,'.')
%
% lvl_err___ = lvl_err_true(~isnan(lvl_err_true));
% %lvl_err___ = lvl_err___-mean(lvl_err___);
% coeffs = arburg(lvl_err___,1000);
% fs_in = 92e9;
% [h,w] = freqz(1,coeffs,length(lvl_err___),"whole",fs_in);
% h = fftshift(h./max(abs(h)));
% freq_vec = linspace(-fs_in/2,fs_in/2,length(h));
% figure(111)
% hold on
% plot(freq_vec.*1e-9,20*log10(h),'DisplayName','burg');
%
% spectrum_plot(y,92e9);
%
% d = 2^nextpow2(length(y)/16);
%
% figure(1111)
% hold on
% pwelch(y,hamming(d),d/2,d,92e9,"centered","power");
end
%% Functions needed During Adaption
function x_in_vnle_format = calcVNLENonlinVecs(~,x_in_block,I_2,I_3,N_,norm_)
% These are the second and third order input signal products of the VNLE EQ
% h1 x_in(k-n1) + h2 x_in(k-n1)*x_in(k-n2) + h3 x_in(k-n1)*x_in(k-n2)*x_in(k-n3)
l1=length(x_in_block);
l2=length(I_2);
l3=length(I_3);
final_length = l1+l2+l3;
x_in_vnle_format = zeros(final_length,1);
idx = l1;
x_in_vnle_format(1:idx) = x_in_block;
if N_(2) > 0
delta_2 = round((N_(1)-N_(2)) / 2);
input_vec_se = x_in_block(delta_2:end) / norm_(2); %TODO normalization step
% Extract columns from I_2
col1 = input_vec_se(I_2(:,1));
col2 = input_vec_se(I_2(:,2));
x2 = col1 .* col2;
x_in_vnle_format(idx+1:idx+l2) = x2;
end
if N_(3) > 0
delta_3 = round((N_(1)-N_(3))/2);
input_vec_th = x_in_block(delta_3:end) / norm_(3);
% Extract columns from I_3
col1 = input_vec_th(I_3(:,1));
col2 = input_vec_th(I_3(:,2));
col3 = input_vec_th(I_3(:,3));
% Perform matrix multiplication
x3 = col1 .* col2 .* col3;
idx = idx+l2;
x_in_vnle_format(idx+1:idx+l3) = x3;
end
end
%% Functions needed for Preparation
function [C] = calcVNLEMemoryLength(~,N)
%calculates the memory length of VNLE
C = zeros(size(N));
for o = 1:numel(N)
switch o
case 1
C(o) = N(o);
case 2
C(o) = N(o)*(N(o)+1) / 2;
case 3
C(o) = N(o)*(N(o)+1)*(N(o)+2) / 6;
end
end
end
function [indvec2nd, indvec3rd] = calcIndiceVectors(~,N)
% Init vectors of 2nd and 3rd order coefficient indices ->
% yield combination with
for order = 2:numel(N)
n = N(order);
v = 1:n; % Ursprünglicher Vektor
row = 1;
% Schleifen zur Generierung des Indize Vektors
switch order
case 2
indvec2nd = zeros(n*(n+1)/2, order);
for i = 1:n
for j = i:n
indvec2nd(row, :) = [v(i) v(j)];
row = row + 1;
end
end
case 3
indvec3rd = zeros(n*(n+1)*(n+2)/6, 3);
for i = 1:n
for j = i:n
for k = j:n
indvec3rd(row, :) = [v(i) v(j) v(k)];
row = row + 1;
end
end
end
end
end
end
function powerNorm = calcPowerNormalization(~,v)
powerNorm(1) = sqrt(mean(abs(v ).^2));
powerNorm(2) = sqrt(mean(abs(v.^2).^2));
powerNorm(3) = sqrt(mean(abs(v.^3).^2));
end
end
end

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@@ -0,0 +1,456 @@
classdef EQ_silas_ofc < handle
%EQ_SILAS FFE and DFE Equalizer Playground
properties
% Important Signals
x_in %Input Sequence to be equalized
x_length
x_norm
d %reference signal
d_norm
d_constellation %constellation points of the reference
y_out %equalizer output signal
% FFE coefficients always named with "e"
Ne
Ce %memory length FFE
Ie1 %Indice Combination of 1nd order FFE
Ie2 %Indice Combination of 2nd order FFE
Ie3 %Indice Combination of 3nd order FFE
e %coefficients for FFE
% DFE coefficients always named with "b"
Nb
Cb %memory length DFE
Ib1 %Indice Combination of 1nd order DFE
Ib2 %Indice Combination of 2nd order DFE
Ib3 %Indice Combination of 3nd order DFE
b %coefficients for DFE
error
e_ffe
e_dfe
e_dc
% coefficients
mu_dc_train
mu_ffe_train
mu_dfe_train
mu_dc_dd
mu_ffe_dd
mu_dfe_dd
mu_combined_dd % [1st order FFE, 2nd order FFE, 3rd order FFE, all orders DFE]
delay
trainlength
sps
trainloops
ddloops
eq_parallelization_blocklength % block lengt of EQ (until now, only the dc subtraction is affected by this)
eq_updatelatency % time in symbols until the calculated updates reach the signal again (until now, only the dc subtraction is affected by this)
eq_avg_blocklength
end
methods
function obj = EQ_silas_ofc(options)
%EQ_SILAS Construct an instance of this class
arguments(Input)
options.Ne = [50 5 0] %Number of FFE coefficients (1st, 2nd and 3rd order)
options.Nb = [30 5 3] %Number of DFE coefficients (1st, 2nd and 3rd order)
options.trainloops = 2;
options.trainlength = 4096;
options.ddloops = 2;
options.delay = 0;
options.sps = 2;
options.mu_dc_train = 0.01;
options.mu_ffe_train = 0.005;
options.mu_dfe_train = 0.005;
options.mu_dc_dd = 0.01;
options.mu_ffe_dd = [0.0004 0.0005 0.0006];
options.mu_dfe_dd = 0.0005;
options.eq_parallelization_blocklength = 1;
options.eq_updatelatency = 1;
options.eq_avg_blocklength = 0;
end
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
% Generate helpful vectors and initialize the filters with
% correct length:
obj.Ce = obj.calcVNLEMemoryLength(obj.Ne);
[obj.Ie2,obj.Ie3] = obj.calcIndiceVectors(obj.Ne);
obj.e = zeros(sum(obj.Ce),1);
obj.Cb = obj.calcVNLEMemoryLength(obj.Nb);
[obj.Ib2,obj.Ib3] = obj.calcIndiceVectors(obj.Nb);
obj.b = zeros(sum(obj.Cb),1);
end
function [signalclass_out] = process(obj,signalclass_in, reference_signalclass_in)
% actual processing of the signal (steps 1. - 3.)
% 1 normalize RMS
signalclass_in = signalclass_in.normalize("mode","rms");
% Process the EQ optimization
obj.process_(signalclass_in.signal', reference_signalclass_in.signal');
signalclass_in.signal = obj.y_out';
% append to logbook
lbdesc = ['EQ von Silas ist gelaufen '];
signalclass_in = signalclass_in.logbookentry(lbdesc);
% write to output
signalclass_out = signalclass_in;
end
function process_(obj,x_in,d_in)
% 1) prepare signals
obj.e_dc = mean(x_in);
% 1.1) Input Signal
obj.x_in = [zeros(1,floor(obj.Ne(1)/2)) x_in zeros(1,obj.Ne(1))];
obj.x_length = length(x_in);
obj.x_norm = obj.calcPowerNormalization(x_in);
% 1.2 Reference Signal // Constellation
obj.d = [zeros(1,obj.Nb(1)-1) d_in zeros(1,obj.Nb(1))];
obj.d_constellation = unique(d_in);
obj.d_norm = obj.calcPowerNormalization(d_in);
% 1.3 Training
obj.trainingMode();
% 1.4 Decision Directed Mode
obj.decisionDirectedMode();
end
%% Adaptive Equalization Modes
function trainingMode(obj)
dc_block = ones(obj.eq_parallelization_blocklength,1);
for tloop = 1:obj.trainloops
m = 1+obj.delay;
dc_cnt = 0;
for n = obj.sps*obj.delay+1:obj.sps:obj.sps*obj.trainlength
m = m+1;
dc_cnt = dc_cnt+1;
%get Sigal input vectors with correct length for VNLE
x_in_block = obj.x_in(obj.Ne(1)+n+(obj.sps-1):-1:n+obj.sps).';
x_in_vnle_format = obj.calcVNLENonlinVecs(x_in_block,obj.Ie2,obj.Ie3,obj.Ne,obj.x_norm);
%get Reference input vectors with correct length for VNLE
d_block = obj.d(obj.Nb(1)-obj.delay+m-2:-1:m-obj.delay-1).';
d_vnle_format = obj.calcVNLENonlinVecs(d_block,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
obj.e_ffe = obj.e.' * x_in_vnle_format;
obj.e_dfe = obj.b.' * d_vnle_format;
% Calculate the Error
obj.error = obj.e_dc + obj.e_ffe - obj.e_dfe - obj.d(obj.Nb(1)-1+m-obj.delay);
if obj.mu_ffe_train ~= 0
%update FFE coefficients with LMS
obj.e = obj.e - obj.error*conj(x_in_vnle_format)*obj.mu_ffe_train;
else
%update FFE coefficients with NLMS
obj.e = obj.e - obj.error*x_in_vnle_format/(x_in_vnle_format.'*x_in_vnle_format);
end
%update DFE coefficients with LMS
obj.b = obj.b + obj.mu_dfe_train*obj.error*d_vnle_format;
%update DC error
dc_block(dc_cnt) = obj.error .* obj.mu_dc_train;
if dc_cnt == obj.eq_parallelization_blocklength
obj.e_dc = obj.e_dc - mean(dc_block(dc_cnt));
dc_cnt = 0;
end
end
end
end
function decisionDirectedMode(obj)
%start the dd mode with coefficients from training
coeff = [obj.e;obj.b];
obj.e_dc = ones(obj.eq_updatelatency,1).*obj.e_dc;
dc_block = ones(obj.eq_parallelization_blocklength,1);
lvl_err_true = NaN(length(obj.d),numel(obj.d_constellation));
for ddloop = 1:obj.ddloops
m = 0;
dc_cnt = 0;
mu_mat = diag([ones(1,obj.Ce(1))*obj.mu_ffe_dd(1)... %1st order ffe
ones(1,obj.Ce(2))*obj.mu_ffe_dd(2)... %2nd order ffe
ones(1,obj.Ce(3))*obj.mu_ffe_dd(3)... %3rd order ffe
ones(1,sum(obj.Cb))*obj.mu_dfe_dd]); %all order dfe
mu_ffe = [ones(1,obj.Ce(1))*obj.mu_ffe_dd(1)... %1st order ffe
ones(1,obj.Ce(2))*obj.mu_ffe_dd(2)... %2nd order ffe
ones(1,obj.Ce(3))*obj.mu_ffe_dd(3)];
mu_dfe = ones(1,sum(obj.Cb))*obj.mu_dfe_dd;
y = zeros(1,floor(obj.x_length/obj.sps));
d_feedback = zeros(obj.Cb(1),1);
d_vnle = obj.calcVNLENonlinVecs(d_feedback,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
d_hat = zeros(obj.x_length,1);
m_reg = 0;
if obj.eq_avg_blocklength > 0
averaging_window = zeros(obj.eq_avg_blocklength,1);
end
for k = 1:obj.sps:obj.x_length
dc_cnt = dc_cnt+1;
m=m+1;
%get Sigal input vectors with correct length for VNLE
x = obj.x_in(obj.Ne(1)+k-1:-1:k).';
%
if obj.eq_avg_blocklength > 0 %% Das läuft gut mit 400er Fenster!!
averaging_window = circshift(averaging_window,obj.sps);
averaging_window(1:obj.sps,1) = x(1:obj.sps);
avg_(k) = mean(averaging_window);
x = x-avg_(k);
end
%bring this signal to "special" VNLE format
x_vnle = obj.calcVNLENonlinVecs(x,obj.Ie2,obj.Ie3,obj.Ne,obj.x_norm);
%combine FFE with DFE to one vector (cursor between the two sequences)
x_d = [x_vnle;-d_vnle];
%Apply filter
%y(m) = (m_reg(end)*dc_cnt + obj.e_dc(end)) + x_d.'* coeff;
if obj.mu_dc_dd > 0
y(m) = obj.e_dc(end) + x_d.'* coeff;
else
y(m) = x_d.'* coeff;
end
% if obj.eq_avg_blocklength > 0 %% Das läuft nicht gut!!
% averaging_window = circshift(averaging_window,obj.sps);
% averaging_window(1:obj.sps,1) = y(m);
% avg_(m) = mean(averaging_window);
% y(m) = y(m)-avg_(m);
% end
%Decision
[~,symbol_idx] = min(abs(y(m) - obj.d_constellation)); % decision for closest constellation point
d_hat(k) = obj.d_constellation(symbol_idx);
%Error between FFE & DFE filtered signal and Decision
obj.error(k) = y(m) - d_hat(k);
lvl_err_true(m,symbol_idx) = y(m) - obj.d(m+1);
% if obj.eq_avg_blocklength > 0 %% Das läuft nicht gut!!
% averaging_window = circshift(averaging_window,obj.sps);
% averaging_window(1:obj.sps,1) = y(m);
% avg_(m) = mean(averaging_window);
% y(m) = y(m)-avg_(m);
% end
%Update FFE and DFE coefficients
coeff = coeff - mu_mat*obj.error(k) * conj(x_d);
%Update DC error
dc_block(dc_cnt) = obj.error(k) ;
if dc_cnt == obj.eq_parallelization_blocklength
if obj.eq_updatelatency > 1
obj.e_dc = circshift(obj.e_dc,1);
% m_reg(end+1) = ((1:obj.eq_parallelization_blocklength)' \ (cumsum(dc_block)));
%
% obj.e_dc(1) = obj.e_dc(2) - sign(m_reg(end)) .* (sum(dc_block).* m_reg(end) .* obj.mu_dc_dd);
obj.e_dc(1) = obj.e_dc(2) - sum(dc_block) .* obj.mu_dc_dd;
else
%m_reg(end+1) = ((1:obj.eq_parallelization_blocklength)' \ (cumsum(dc_block)));
% obj.e_dc = obj.e_dc - sign(m_reg(end)) .* (sum(dc_block).* m_reg(end) .* obj.mu_dc_dd);
obj.e_dc = obj.e_dc - sum(dc_block) .* obj.mu_dc_dd;
end
dc_cnt = 0;
end
% Append new decision to decision feedback
if obj.Nb(1) > 0
%shift up one index
d_feedback(2:end) = d_feedback(1:end-1);
%replace 1st index with current estimation
d_feedback(1) = d_hat(k);
%build memorylike VNLE version
d_vnle = obj.calcVNLENonlinVecs(d_feedback,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
end
end
end
obj.y_out = (circshift( y.' ,-(obj.delay))).';
end
%% Functions needed During Adaption
function x_in_vnle_format = calcVNLENonlinVecs(~,x_in_block,I_2,I_3,N_,norm_)
% These are the second and third order input signal products of the VNLE EQ
% h1 x_in(k-n1) + h2 x_in(k-n1)*x_in(k-n2) + h3 x_in(k-n1)*x_in(k-n2)*x_in(k-n3)
x1 = x_in_block;
x2 = [];
x3 = [];
if N_(2) > 0
delta_2 = round((N_(1)-N_(2))/2);
input_vec_se = x_in_block(delta_2:end)/norm_(2); %TODO normalization step
x2 = input_vec_se(I_2(:,1)).*input_vec_se(I_2(:,2));
end
if N_(3) > 0
delta_3 = round((N_(1)-N_(3))/2);
input_vec_th = x_in_block(delta_3:end)/norm_(3);
x3 = input_vec_th(I_3(:,1)).*input_vec_th(I_3(:,2)).*input_vec_th(I_3(:,3));
end
x_in_vnle_format = [x1;x2;x3];
end
%% Functions needed for Preparation
function [C] = calcVNLEMemoryLength(~,N)
%calculates the memory length of VNLE
C = zeros(size(N));
for o = 1:numel(N)
switch o
case 1
C(o) = N(o);
case 2
C(o) = N(o)*(N(o)+1) / 2;
case 3
C(o) = N(o)*(N(o)+1)*(N(o)+2) / 6;
end
end
end
function [indvec2nd, indvec3rd] = calcIndiceVectors(~,N)
% Init vectors of 2nd and 3rd order coefficient indices ->
% yield combination with
for order = 2:numel(N)
n = N(order);
v = 1:n; % Ursprünglicher Vektor
row = 1;
% Schleifen zur Generierung des Indize Vektors
switch order
case 2
indvec2nd = zeros(n*(n+1)/2, order);
for i = 1:n
for j = i:n
indvec2nd(row, :) = [v(i) v(j)];
row = row + 1;
end
end
case 3
indvec3rd = zeros(n*(n+1)*(n+2)/6, 3);
for i = 1:n
for j = i:n
for k = j:n
indvec3rd(row, :) = [v(i) v(j) v(k)];
row = row + 1;
end
end
end
end
end
end
function powerNorm = calcPowerNormalization(~,v)
powerNorm(1) = sqrt(mean(abs(v ).^2));
powerNorm(2) = sqrt(mean(abs(v.^2).^2));
powerNorm(3) = sqrt(mean(abs(v.^3).^2));
end
end
end

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classdef EQ_silas_plain < handle
%EQ_SILAS FFE and DFE Equalizer Playground
properties
% Important Signals
x_in %Input Sequence to be equalized
x_length
x_norm
d %reference signal
d_norm
d_constellation %constellation points of the reference
y_out %equalizer output signal
% FFE coefficients always named with "e"
Ne
Ce %memory length FFE
Ie1 %Indice Combination of 1nd order FFE
Ie2 %Indice Combination of 2nd order FFE
Ie3 %Indice Combination of 3nd order FFE
e %coefficients for FFE
% DFE coefficients always named with "b"
Nb
Cb %memory length DFE
Ib1 %Indice Combination of 1nd order DFE
Ib2 %Indice Combination of 2nd order DFE
Ib3 %Indice Combination of 3nd order DFE
b %coefficients for DFE
error
e_ffe
e_dfe
e_dc
error_log
mu_dc_train
mu_ffe_train
mu_dfe_train
mu_dc_dd
mu_combined_dd
delay
trainlength
sps
trainloops
ddloops
end
methods
function obj = EQ_silas_plain(options)
%EQ_SILAS Construct an instance of this class
arguments(Input)
options.Ne = [50 5 0] %Number of FFE coefficients (1st, 2nd and 3rd order)
options.Nb = [30 5 3] %Number of DFE coefficients (1st, 2nd and 3rd order)
options.trainloops = 2;
options.trainlength = 4096;
options.ddloops = 2;
options.delay = 0;
options.sps = 2;
options.mu_dc_train = 0.01;
options.mu_ffe_train = 0.005;
options.mu_dfe_train = 0.005;
options.mu_dc_dd = 0.01;
options.mu_combined_dd = [0.0004 0.0005 0.0006 0.0007 ];
end
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
% Generate helpful vectors and initialize the filters with
% correct length:
obj.Ce = obj.calcVNLEMemoryLength(obj.Ne);
[obj.Ie2,obj.Ie3] = obj.calcIndiceVectors(obj.Ne);
obj.e = zeros(sum(obj.Ce),1);
obj.Cb = obj.calcVNLEMemoryLength(obj.Nb);
[obj.Ib2,obj.Ib3] = obj.calcIndiceVectors(obj.Nb);
obj.b = zeros(sum(obj.Cb),1);
end
function [signalclass_out,error_log] = process(obj,signalclass_in, reference_signalclass_in)
assert(signalclass_in.fs / reference_signalclass_in.fs == obj.sps)
% actual processing of the signal (steps 1. - 3.)
% 1 normalize RMS
signalclass_in = signalclass_in.normalize("mode","rms");
% Process the EQ optimization
obj.process_(signalclass_in.signal', reference_signalclass_in.signal');
signalclass_in.signal = obj.y_out';
%change sampling frequency of outgoing signal
signalclass_in.fs = reference_signalclass_in.fs;
% append to logbook
lbdesc = ['EQ von Silas ist gelaufen '];
signalclass_in = signalclass_in.logbookentry(lbdesc);
% write to output
signalclass_out = signalclass_in;
end
function process_(obj,x_in,d_in)
% 1) prepare signals
obj.e_dc = mean(x_in);
% 1.1) Input Signal
obj.x_in = [zeros(1,floor(obj.Ne(1)/2)) x_in zeros(1,obj.Ne(1))];
obj.x_length = length(x_in);
obj.x_norm = obj.calcPowerNormalization(x_in);
% 1.2 Reference Signal // Constellation
obj.d = [zeros(1,obj.Nb(1)-1) d_in zeros(1,obj.Nb(1))];
obj.d_constellation = unique(d_in);
obj.d_norm = obj.calcPowerNormalization(d_in);
% 1.3 Training
obj.trainingMode();
% 1.4 Decision Directed Mode
obj.decisionDirectedMode();
end
%% Adaptive Equalization Modes
function trainingMode(obj)
for tloop = 1:obj.trainloops
m = 1+obj.delay;
cnt = 1;
for n = obj.sps*obj.delay+1:obj.sps:obj.sps*obj.trainlength
m = m+1;
%get Sigal input vectors with correct length for VNLE
x_in_block = obj.x_in(obj.Ne(1)+n+(obj.sps-1):-1:n+obj.sps).';
x_in_vnle_format = obj.calcVNLENonlinVecs(x_in_block,obj.Ie2,obj.Ie3,obj.Ne,obj.x_norm);
%get Reference input vectors with correct length for VNLE
d_block = obj.d(obj.Nb(1)-obj.delay+m-2:-1:m-obj.delay-1).';
d_vnle_format = obj.calcVNLENonlinVecs(d_block,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
% Calculate the Error
obj.e_ffe = obj.e.' * x_in_vnle_format;
obj.e_dfe = obj.b.' * d_vnle_format;
obj.error = obj.e_dc + obj.e_ffe - obj.e_dfe - obj.d(obj.Nb(1)-1+m-obj.delay);
obj.error_log(tloop,cnt) = obj.error;
%update FFE coefficients with LMS
obj.e = obj.e - obj.error*conj(x_in_vnle_format)*obj.mu_ffe_train;
%update DFE coefficients with LMS
obj.b = obj.b + obj.mu_dfe_train*obj.error*d_vnle_format;
%update DC error
obj.e_dc = obj.e_dc - obj.error .* obj.mu_dc_train;
cnt = cnt+1;
end
end
end
function decisionDirectedMode(obj)
%start the dd mode with coefficients from training
coeff = [obj.e;obj.b];
for ddloop = 1:obj.ddloops
m = 0;
if all(obj.mu_combined_dd == obj.mu_combined_dd(1))
mu_mat = obj.mu_combined_dd(1);
else
mu_mat = diag([ones(1,obj.Ce(1))*obj.mu_combined_dd(1)... %1st order ffe
ones(1,obj.Ce(2))*obj.mu_combined_dd(2)... %2nd order ffe
ones(1,obj.Ce(3))*obj.mu_combined_dd(3)... %3rd order ffe
ones(1,sum(obj.Cb))*obj.mu_combined_dd(4)]); %all order dfe
end
y = zeros(1,floor(obj.x_length/obj.sps));
d_feedback = zeros(obj.Cb(1),1);
d_vnle = obj.calcVNLENonlinVecs(d_feedback,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
d_hat = zeros(obj.x_length,1);
for k = 1:obj.sps:obj.x_length
m=m+1;
%get Sigal input vectors with correct length for VNLE
x = obj.x_in(obj.Ne(1)+k-1:-1:k).';
x_vnle = obj.calcVNLENonlinVecs(x,obj.Ie2,obj.Ie3,obj.Ne,obj.x_norm);
%combine FFE with DFE to one vector (cursor between the two sequences)
x_d = [x_vnle;-d_vnle];
%Apply filter
y(m) = obj.e_dc + x_d.'* coeff;
%Decision
[~,symbol_idx] = min(abs(y(m) - obj.d_constellation)); % decision for closest constellation point
d_hat(k) = obj.d_constellation(symbol_idx);
%Error between FFE & DFE filtered signal and Decision
obj.error = y(m) - d_hat(k);
%Update coefficients (both FFE and DFE)
coeff = coeff - (mu_mat * (obj.error * conj(x_d)));
if 1 %mu_mat ~= 0
obj.e_dc = obj.e_dc - obj.mu_dc_dd * obj.error;
end
% Append new decision to decision feedback
if obj.Nb(1) > 0
%shift up one index
d_feedback(2:end) = d_feedback(1:end-1);
%replace 1st index with current estimation
d_feedback(1) = d_hat(k);
%build memorylike VNLE version
d_vnle = obj.calcVNLENonlinVecs(d_feedback,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
end
end
end
obj.y_out = (circshift( y.' ,-(obj.delay))).';
end
%% Functions needed During Adaption
function x_in_vnle_format = calcVNLENonlinVecs(~,x_in_block,I_2,I_3,N_,norm_)
% These are the second and third order input signal products of the VNLE EQ
% h1 x_in(k-n1) + h2 x_in(k-n1)*x_in(k-n2) + h3 x_in(k-n1)*x_in(k-n2)*x_in(k-n3)
l1=length(x_in_block);
l2=length(I_2);
l3=length(I_3);
final_length = l1+l2+l3;
x_in_vnle_format = zeros(final_length,1);
idx = l1;
x_in_vnle_format(1:idx) = x_in_block;
if N_(2) > 0
delta_2 = round((N_(1)-N_(2)) / 2);
input_vec_se = x_in_block(delta_2:end) / norm_(2); %TODO normalization step
% Extract columns from I_2
col1 = input_vec_se(I_2(:,1));
col2 = input_vec_se(I_2(:,2));
x2 = col1 .* col2;
x_in_vnle_format(idx+1:idx+l2) = x2;
end
if N_(3) > 0
delta_3 = round((N_(1)-N_(3))/2);
input_vec_th = x_in_block(delta_3:end) / norm_(3);
% Extract columns from I_3
col1 = input_vec_th(I_3(:,1));
col2 = input_vec_th(I_3(:,2));
col3 = input_vec_th(I_3(:,3));
% Perform matrix multiplication
x3 = col1 .* col2 .* col3;
idx = idx+l2;
x_in_vnle_format(idx+1:idx+l3) = x3;
end
end
%% Functions needed for Preparation
function [C] = calcVNLEMemoryLength(~,N)
%calculates the memory length of VNLE
C = zeros(size(N));
for o = 1:numel(N)
switch o
case 1
C(o) = N(o);
case 2
C(o) = N(o)*(N(o)+1) / 2;
case 3
C(o) = N(o)*(N(o)+1)*(N(o)+2) / 6;
end
end
end
function [indvec2nd, indvec3rd] = calcIndiceVectors(~,N)
% Init vectors of 2nd and 3rd order coefficient indices ->
% yield combination with
for order = 2:numel(N)
n = N(order);
v = 1:n; % Ursprünglicher Vektor
row = 1;
% Schleifen zur Generierung des Indize Vektors
switch order
case 2
indvec2nd = zeros(n*(n+1)/2, order);
for i = 1:n
for j = i:n
indvec2nd(row, :) = [v(i) v(j)];
row = row + 1;
end
end
case 3
indvec3rd = zeros(n*(n+1)*(n+2)/6, 3);
for i = 1:n
for j = i:n
for k = j:n
indvec3rd(row, :) = [v(i) v(j) v(k)];
row = row + 1;
end
end
end
end
end
end
function powerNorm = calcPowerNormalization(~,v)
powerNorm(1) = sqrt(mean(abs(v ).^2));
powerNorm(2) = sqrt(mean(abs(v.^2).^2));
powerNorm(3) = sqrt(mean(abs(v.^3).^2));
end
end
end

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classdef EQ_silas_sliding_window_dc_removal < handle
%EQ_SILAS FFE and DFE Equalizer Playground
properties
% Important Signals
x_in %Input Sequence to be equalized
x_length
x_norm
d %reference signal
d_norm
d_constellation %constellation points of the reference
y_out %equalizer output signal
% FFE coefficients always named with "e"
Ne
Ce %memory length FFE
Ie1 %Indice Combination of 1nd order FFE
Ie2 %Indice Combination of 2nd order FFE
Ie3 %Indice Combination of 3nd order FFE
e %coefficients for FFE
% DFE coefficients always named with "b"
Nb
Cb %memory length DFE
Ib1 %Indice Combination of 1nd order DFE
Ib2 %Indice Combination of 2nd order DFE
Ib3 %Indice Combination of 3nd order DFE
b %coefficients for DFE
error
e_ffe
e_dfe
e_dc
% coefficients
mu_dc_train
mu_ffe_train
mu_dfe_train
mu_dc_dd
mu_ffe_dd
mu_dfe_dd
mu_combined_dd % [1st order FFE, 2nd order FFE, 3rd order FFE, all orders DFE]
delay
trainlength
sps
trainloops
ddloops
eq_blocklength % block lengt of EQ (until now, only the dc subtraction is affected by this)
eq_updatelatency % time in symbols until the calculated updates reach the signal again (until now, only the dc subtraction is affected by this)
end
methods
function obj = EQ_silas_sliding_window_dc_removal(options)
%EQ_SILAS Construct an instance of this class
arguments(Input)
options.Ne = [50 5 0] %Number of FFE coefficients (1st, 2nd and 3rd order)
options.Nb = [30 5 3] %Number of DFE coefficients (1st, 2nd and 3rd order)
options.trainloops = 2;
options.trainlength = 4096;
options.ddloops = 2;
options.delay = 0;
options.sps = 2;
options.mu_dc_train = 0.01;
options.mu_ffe_train = 0.005;
options.mu_dfe_train = 0.005;
options.mu_dc_dd = 0.01;
options.mu_ffe_dd = [0.0004 0.0005 0.0006];
options.mu_dfe_dd = 0.0005;
options.eq_blocklength = 1;
options.eq_updatelatency = 1;
end
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
% Generate helpful vectors and initialize the filters with
% correct length:
obj.Ce = obj.calcVNLEMemoryLength(obj.Ne);
[obj.Ie2,obj.Ie3] = obj.calcIndiceVectors(obj.Ne);
obj.e = zeros(sum(obj.Ce),1);
obj.Cb = obj.calcVNLEMemoryLength(obj.Nb);
[obj.Ib2,obj.Ib3] = obj.calcIndiceVectors(obj.Nb);
obj.b = zeros(sum(obj.Cb),1);
end
function [signalclass_out] = process(obj,signalclass_in, reference_signalclass_in)
% actual processing of the signal (steps 1. - 3.)
% 1 normalize RMS
signalclass_in = signalclass_in.normalize("mode","rms");
% Process the EQ optimization
obj.process_(signalclass_in.signal', reference_signalclass_in.signal');
signalclass_in.signal = obj.y_out';
% append to logbook
lbdesc = ['EQ von Silas ist gelaufen '];
signalclass_in = signalclass_in.logbookentry(lbdesc);
% write to output
signalclass_out = signalclass_in;
end
function process_(obj,x_in,d_in)
% 1) prepare signals
obj.e_dc = mean(x_in);
% 1.1) Input Signal
obj.x_in = [zeros(1,floor(obj.Ne(1)/2)) x_in zeros(1,obj.Ne(1))];
obj.x_length = length(x_in);
obj.x_norm = obj.calcPowerNormalization(x_in);
% 1.2 Reference Signal // Constellation
obj.d = [zeros(1,obj.Nb(1)-1) d_in zeros(1,obj.Nb(1))];
obj.d_constellation = unique(d_in);
obj.d_norm = obj.calcPowerNormalization(d_in);
% 1.3 Training
obj.trainingMode();
% 1.4 Decision Directed Mode
obj.decisionDirectedMode();
end
%% Adaptive Equalization Modes
function trainingMode(obj)
dc_avg_block = zeros(obj.eq_blocklength,1);
for tloop = 1:obj.trainloops
m = 1+obj.delay;
for n = obj.sps*obj.delay+1:obj.sps:obj.sps*obj.trainlength
m = m+1;
%get Sigal input vectors with correct length for VNLE
x_in_block = obj.x_in(obj.Ne(1)+n+(obj.sps-1):-1:n+obj.sps).';
x_in_vnle_format = obj.calcVNLENonlinVecs(x_in_block,obj.Ie2,obj.Ie3,obj.Ne,obj.x_norm);
%get Reference input vectors with correct length for VNLE
d_block = obj.d(obj.Nb(1)-obj.delay+m-2:-1:m-obj.delay-1).';
d_vnle_format = obj.calcVNLENonlinVecs(d_block,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
obj.e_ffe = obj.e.' * x_in_vnle_format;
dc_avg_block = circshift(dc_avg_block,1);
dc_avg_block(1) = obj.e_ffe;
if n > obj.eq_blocklength * obj.sps
obj.e_dc = obj.e_ffe - mean(dc_avg_block).* obj.mu_dc_train;
else
obj.e_dc = 0;
end
obj.e_dfe = obj.b.' * d_vnle_format;
% Calculate the Error
obj.error = obj.e_ffe - obj.e_dfe - obj.d(obj.Nb(1)-1+m-obj.delay);
if obj.mu_ffe_train ~= 0
%update FFE coefficients with LMS
obj.e = obj.e - obj.error*conj(x_in_vnle_format)*obj.mu_ffe_train;
else
%update FFE coefficients with NLMS
obj.e = obj.e - obj.error*x_in_vnle_format/(x_in_vnle_format.'*x_in_vnle_format);
end
%update DFE coefficients with LMS
obj.b = obj.b + obj.mu_dfe_train*obj.error*d_vnle_format;
end
end
end
function decisionDirectedMode(obj)
%start the dd mode with coefficients from training
coeff = [obj.e;obj.b];
for ddloop = 1:obj.ddloops
dc_avg_block = zeros(obj.eq_blocklength,1);
m = 0;
dc_cnt = 0;
mu_mat = diag([ones(1,obj.Ce(1))*obj.mu_ffe_dd(1)... %1st order ffe
ones(1,obj.Ce(2))*obj.mu_ffe_dd(2)... %2nd order ffe
ones(1,obj.Ce(3))*obj.mu_ffe_dd(3)... %3rd order ffe
ones(1,sum(obj.Cb))*obj.mu_dfe_dd]); %all order dfe
mu_ffe = [ones(1,obj.Ce(1))*obj.mu_ffe_dd(1)... %1st order ffe
ones(1,obj.Ce(2))*obj.mu_ffe_dd(2)... %2nd order ffe
ones(1,obj.Ce(3))*obj.mu_ffe_dd(3)];
mu_dfe = ones(1,sum(obj.Cb))*obj.mu_dfe_dd;
y = zeros(1,floor(obj.x_length/obj.sps));
y_= zeros(1,floor(obj.x_length/obj.sps));
d_feedback = zeros(obj.Cb(1),1);
d_vnle = obj.calcVNLENonlinVecs(d_feedback,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
d_hat = zeros(obj.x_length,1);
for k = 1:obj.sps:obj.x_length
dc_cnt = dc_cnt+1;
m=m+1;
%get Sigal input vectors with correct length for VNLE
x = obj.x_in(obj.Ne(1)+k-1:-1:k).';
x_vnle = obj.calcVNLENonlinVecs(x,obj.Ie2,obj.Ie3,obj.Ne,obj.x_norm);
%combine FFE with DFE to one vector (cursor between the two sequences)
x_d = [x_vnle;-d_vnle];
%Apply filter
y_(m) = x_d.'* coeff ;
y(m) = y_(m) - obj.e_dc(end) ;
dc_avg_block = circshift(dc_avg_block,1);
dc_avg_block(1) = y(m);
obj.e_dc(m) = (y(m) - mean(dc_avg_block)) .* obj.mu_dc_dd;
%Decision
[~,symbol_idx] = min(abs(y(m) - obj.d_constellation)); % decision for closest constellation point
d_hat(k) = obj.d_constellation(symbol_idx);
%Error between FFE & DFE filtered signal and Decision
obj.error = y(m) - d_hat(k);
%Update coefficients (both FFE and DFE)
% obj.e = obj.e - obj.error * mu_ffe * conj(x_vnle);
% obj.b = obj.b + obj.error * mu_dfe * conj(d_vnle);
% coeff = [obj.e;obj.b];
coeff = coeff - mu_mat*obj.error*conj(x_d);
% Append new decision to decision feedback
if obj.Nb(1) > 0
%shift up one index
d_feedback(2:end) = d_feedback(1:end-1);
%replace 1st index with current estimation
d_feedback(1) = d_hat(k);
%build memorylike VNLE version
d_vnle = obj.calcVNLENonlinVecs(d_feedback,obj.Ib2,obj.Ib3,obj.Nb,obj.d_norm);
end
end
end
obj.y_out = (circshift( y.' ,-(obj.delay))).';
end
%% Functions needed During Adaption
function x_in_vnle_format = calcVNLENonlinVecs(~,x_in_block,I_2,I_3,N_,norm_)
% These are the second and third order input signal products of the VNLE EQ
% h1 x_in(k-n1) + h2 x_in(k-n1)*x_in(k-n2) + h3 x_in(k-n1)*x_in(k-n2)*x_in(k-n3)
l1=length(x_in_block);
l2=length(I_2);
l3=length(I_3);
final_length = l1+l2+l3;
x_in_vnle_format = zeros(final_length,1);
idx = l1;
x_in_vnle_format(1:idx) = x_in_block;
if N_(2) > 0
delta_2 = round((N_(1)-N_(2)) / 2);
input_vec_se = x_in_block(delta_2:end) / norm_(2); %TODO normalization step
% Extract columns from I_2
col1 = input_vec_se(I_2(:,1));
col2 = input_vec_se(I_2(:,2));
x2 = col1 .* col2;
x_in_vnle_format(idx+1:idx+l2) = x2;
end
if N_(3) > 0
delta_3 = round((N_(1)-N_(3))/2);
input_vec_th = x_in_block(delta_3:end) / norm_(3);
% Extract columns from I_3
col1 = input_vec_th(I_3(:,1));
col2 = input_vec_th(I_3(:,2));
col3 = input_vec_th(I_3(:,3));
% Perform matrix multiplication
x3 = col1 .* col2 .* col3;
idx = idx+l2;
x_in_vnle_format(idx+1:idx+l3) = x3;
end
end
%% Functions needed for Preparation
function [C] = calcVNLEMemoryLength(~,N)
%calculates the memory length of VNLE
C = zeros(size(N));
for o = 1:numel(N)
switch o
case 1
C(o) = N(o);
case 2
C(o) = N(o)*(N(o)+1) / 2;
case 3
C(o) = N(o)*(N(o)+1)*(N(o)+2) / 6;
end
end
end
function [indvec2nd, indvec3rd] = calcIndiceVectors(~,N)
% Init vectors of 2nd and 3rd order coefficient indices ->
% yield combination with
for order = 2:numel(N)
n = N(order);
v = 1:n; % Ursprünglicher Vektor
row = 1;
% Schleifen zur Generierung des Indize Vektors
switch order
case 2
indvec2nd = zeros(n*(n+1)/2, order);
for i = 1:n
for j = i:n
indvec2nd(row, :) = [v(i) v(j)];
row = row + 1;
end
end
case 3
indvec3rd = zeros(n*(n+1)*(n+2)/6, 3);
for i = 1:n
for j = i:n
for k = j:n
indvec3rd(row, :) = [v(i) v(j) v(k)];
row = row + 1;
end
end
end
end
end
end
function powerNorm = calcPowerNormalization(~,v)
powerNorm(1) = sqrt(mean(abs(v ).^2));
powerNorm(2) = sqrt(mean(abs(v.^2).^2));
powerNorm(3) = sqrt(mean(abs(v.^3).^2));
end
end
end

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classdef FFE < handle
% Implementation of plain and simple FFE.
% 1) Training mode (stable performance when you use NLMS)
% 2) Decision directed mode
% Eq = FFE("epochs_tr",5,"epochs_dd",5,"len_tr",4096*2,"mu_dd",1e-4,"mu_tr",0,"order",25,"sps",2,"decide",0);
properties
sps % usually 2
order
e
error
len_tr
mu_tr
epochs_tr
mu_dd
epochs_dd
constellation
decide
end
methods
function obj = FFE(options)
arguments(Input)
options.sps = 2;
options.order = 15;
options.len_tr = 4096;
options.mu_tr = 0;
options.epochs_tr = 5;
options.mu_dd = 1e-5;
options.epochs_dd = 5;
options.decide = false;
end
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
obj.e = zeros(obj.order,1);
obj.error = 0;
end
function [X] = process(obj, X, D)
% actual processing of the signal (steps 1. - 3.)
% 1 normalize RMS
X = X.normalize("mode","rms");
obj.constellation = unique(D.signal);
% Training Mode
training = 1;
showviz = 0;
obj.equalize(X.signal, D.signal,obj.mu_tr,obj.epochs_tr,obj.len_tr,training,showviz);
% Decision Directed Mode
N = X.length;
training = 0;
showviz = 0;
[signal,decision]=obj.equalize(X.signal, D.signal,obj.mu_dd,obj.epochs_dd,N,training,showviz);
% Output Signal
if obj.decide
X.signal = decision;
else
X.signal = signal;
end
X.fs = D.fs; %change sampling frequency of outgoing signal from fdac e.g. 2 sps to symbol spaced = fsym
lbdesc = [num2str(obj.order),' tap FFE'];
X = X.logbookentry(lbdesc); % append to logbook
end
function [y,d_hat] = equalize(obj,x,d,mio,epochs,N,training,showviz)
arguments
obj
x
d
mio
epochs
N
training
showviz
end
x = [zeros(floor(obj.order/2),1); x; zeros(obj.order,1)];
if showviz
f = figure(111);
subplot(2,2,1:2);
hold on
a = scatter(1:numel(x),x,1,'.');
a2 = scatter(1,1,1,'.');
a3 = scatter(1,1,2,'.');
a4 = xline(1);
ylim([-3 3])
xlim([0 length(x)]);
% subplot(2,2,3)
% dplot = x(1:1+500);
% b = scatter(1:numel(dplot),dplot,5,'x');
% xline(1)
% xline(obj.order)
% ylim([-3 3])
% xlim([0 500]);
subplot(2,2,3:4)
c = stem(obj.e);
ylim([-1 1])
drawnow
end
for epoch = 1 : epochs
symbol = 0;
for sample = 1 : obj.sps : N
symbol = symbol+1;
U = x(obj.order+sample-1:-1:sample);
y(symbol,1) = obj.e.' * U; % Calculating output of LMS __ * |
if training
d_hat(symbol,1) = d(symbol);
else
[~,symbol_idx] = min(abs(y(symbol) - obj.constellation)); % decision for closest constellation point
d_hat(symbol,1) = obj.constellation(symbol_idx);
end
err(symbol) = y(symbol) - d_hat(symbol); % Instantaneous error
true_err(symbol) = y(symbol) - d(symbol); % Instantaneous error
if mio ~= 0
obj.e = obj.e - (mio * err(symbol) * U) ; % Weight update rule of LMS
else
normalizationfactor = (U.' * U);
obj.e = obj.e - err(symbol) * U / normalizationfactor; % Weight update rule of NLMS
end
if mod(sample,100) == 1 && showviz
a2.XData = 1:2*numel(y);
a2.YData = repelem(y, 2);
a3.XData = 1:2*numel(d_hat);
a3.YData = repelem(d_hat, 2);
a4.Value = sample;
% b.YData = x(symbol:symbol+500);
c.YData = obj.e;
drawnow;
end
obj.error(epoch,symbol) = err(symbol) * err(symbol)'; % Instantaneous square error
end
end
end
end
end

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classdef FFE_DCremoval < handle
% Implementation of plain and simple FFE.
% 1) Training mode (stable performance when you use NLMS)
% 2) Decision directed mode
% Eq = FFE("epochs_tr",5,"epochs_dd",5,"len_tr",4096*2,"mu_dd",1e-4,"mu_tr",0,"order",25,"sps",2,"decide",0);
properties
sps % usually 2
order
e
error
len_tr
mu_tr
epochs_tr
mu_dd
epochs_dd
mu_dc
dc_buffer_len
constellation
decide
end
methods
function obj = FFE_DCremoval(options)
arguments(Input)
options.sps = 2;
options.order = 15;
options.len_tr = 4096;
options.mu_tr = 0;
options.epochs_tr = 5;
options.mu_dd = 1e-5;
options.epochs_dd = 5;
options.mu_dc = 0.05;
options.dc_buffer_len = 1;
options.decide = false;
end
assert(options.dc_buffer_len>0);
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
obj.e = zeros(obj.order,1);
obj.error = 0;
end
function [X] = process(obj, X, D)
% actual processing of the signal (steps 1. - 3.)
% 1 normalize RMS
X = X.normalize("mode","rms");
obj.constellation = unique(D.signal);
% Training Mode
training = 1;
obj.equalize(X.signal, D.signal,obj.mu_tr,obj.epochs_tr,obj.len_tr,training);
% Decision Directed Mode
N = X.length;
training = 0;
[signal,decision]=obj.equalize(X.signal, D.signal,obj.mu_dd,obj.epochs_dd,N,training);
% Output Signal
if obj.decide
X.signal = decision;
else
X.signal = signal;
end
X.fs = D.fs; %change sampling frequency of outgoing signal from fdac e.g. 2 sps to symbol spaced = fsym
lbdesc = [num2str(obj.order),' tap FFE'];
X = X.logbookentry(lbdesc); % append to logbook
end
function [y,d_hat] = equalize(obj,x,d,mio,epochs,N,training)
arguments
obj
x
d
mio
epochs
N
training
end
x = [zeros(floor(obj.order/2),1); x; zeros(obj.order,1)];
err = 0;
e_dc_buffer = NaN(obj.dc_buffer_len,1);
e_dc_est = 0;
for epoch = 1 : epochs
symbol = 0;
for sample = 1 : obj.sps : N
symbol = symbol+1;
U = x(obj.order+sample-1:-1:sample);
y(symbol,1) = e_dc_est + obj.e.' * U; % Calculating output of LMS __ * |
if training
d_hat(symbol,1) = d(symbol);
else
[~,symbol_idx] = min(abs(y(symbol) - obj.constellation)); % decision for closest constellation point
d_hat(symbol,1) = obj.constellation(symbol_idx);
end
err(symbol) = y(symbol) - d_hat(symbol); % Instantaneous error
if mio ~= 0
obj.e = obj.e - (mio * err(symbol) * U) ; % Weight update rule of LMS
else
normalizationfactor = (U.' * U);
obj.e = obj.e - err(symbol) * U / normalizationfactor; % Weight update rule of NLMS
end
%Update the dc estimation every n-th symbol. This is a
%trivial implementation of parallel EQ´s where the
%errors are not apparent in every step. See Silas OFC
%2023 "MPI mitigation adaptive DC removal
if mod(symbol,length(e_dc_buffer)) == 0
e_dc_buffer(1) = e_dc_est - obj.mu_dc * err(symbol);
e_dc_buffer = circshift(e_dc_buffer,1);
e_dc_est = mean(e_dc_buffer,"omitnan");
else
e_dc_buffer(1) = e_dc_est - obj.mu_dc * err(symbol);
e_dc_buffer = circshift(e_dc_buffer,1);
end
obj.error(epoch,symbol) = err(symbol) * err(symbol)'; % Instantaneous square error
end
end
end
end
end

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classdef FFE_DFE < handle
% Implementation of plain and simple FFE.
% 1) Training mode (stable performance when you use NLMS)
% 2) Decision directed mode
% Eq = FFE_DFE("epochs_tr",5,"epochs_dd",5,"len_tr",4096*2,"ffe_mu_dd",1e-4,"dfe_mu_dd",5e-4,"ffe_mu_tr",0,"dfe_mu_tr",0,"ffe_order",21,"dfe_order",0,"sps",2,"decide",1);
properties
sps % usually 2
ffe_order
dfe_order
e
b
error
len_tr
ffe_mu_tr
dfe_mu_tr
epochs_tr
ffe_mu_dd
dfe_mu_dd
epochs_dd
constellation
decide
end
methods
function obj = FFE_DFE(options)
arguments(Input)
options.sps = 2;
options.ffe_order = 15;
options.dfe_order = 2;
options.len_tr = 4096;
options.ffe_mu_tr = 0;
options.dfe_mu_tr = 0;
options.epochs_tr = 5;
options.ffe_mu_dd = 1e-5;
options.dfe_mu_dd = 1e-5;
options.epochs_dd = 5;
options.decide = false;
end
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
obj.e = zeros(obj.ffe_order,1);
obj.b = zeros(obj.dfe_order,1);
obj.error = 0;
end
function [X] = process(obj, X, D)
% actual processing of the signal (steps 1. - 3.)
% 1 normalize RMS
X = X.normalize("mode","rms");
obj.constellation = unique(D.signal);
% Training Mode
training = 1;
showviz = 0;
obj.equalize(X.signal, D.signal,obj.ffe_mu_tr,obj.dfe_mu_tr,obj.epochs_tr,obj.len_tr,training,showviz);
% Decision Directed Mode
N = X.length;
training = 0;
showviz = 0;
[signal,decision]=obj.equalize(X.signal, D.signal,obj.ffe_mu_dd,obj.dfe_mu_dd,obj.epochs_dd,N,training,showviz);
% Output Signal
if obj.decide
X.signal = decision;
else
X.signal = signal;
end
X.fs = D.fs; %change sampling frequency of outgoing signal from fdac e.g. 2 sps to symbol spaced = fsym
lbdesc = [num2str(obj.ffe_order),' tap FFE'];
X = X.logbookentry(lbdesc); % append to logbook
end
function [y,d_hat] = equalize(obj,x,d,ffe_mu,dfe_mu,epochs,N,training,showviz)
arguments
obj
x
d
ffe_mu
dfe_mu
epochs
N
training
showviz
end
mu = diag([ones(1,obj.ffe_order(1))*ffe_mu(1) ...
ones(1,obj.dfe_order(1))*dfe_mu(1) ]);
x = [zeros(floor(obj.ffe_order/2),1); x; zeros(obj.ffe_order,1)];
%d = [zeros(obj.dfe_order-1,1); d; zeros(obj.dfe_order,1)];
d_ = zeros(obj.dfe_order(1),1);
coeff = [obj.e;obj.b];
if showviz
f = figure(111);
subplot(2,2,1:2);
hold on
a = scatter(1:numel(x),x,1,'.');
a2 = scatter(1,1,1,'.');
a3 = scatter(1,1,2,'.');
a4 = xline(1);
ylim([-3 3])
xlim([0 length(x)]);
subplot(2,2,3:4)
c = stem(obj.e);
ylim([-1 1])
drawnow
end
for epoch = 1 : epochs
symbol = 0;
for sample = 1 : obj.sps : N
symbol = symbol+1;
x_ = x(obj.ffe_order+sample-1:-1:sample);
v = [x_;d_];
y(symbol,1) = coeff.' * v; % Calculating output of LMS __ * |
if training
d_hat(symbol,1) = d(symbol);
else
[~,symbol_idx] = min(abs(y(symbol) - obj.constellation)); % decision for closest constellation point
d_hat(symbol,1) = obj.constellation(symbol_idx);
end
err(symbol) = y(symbol) - d_hat(symbol); % Instantaneous error
if ~all(mu == 0,'all') %not all mu values are zero
coeff = coeff - (mu * err(symbol) * v) ; % Weight update rule of LMS
else
normalizationfactor = (v.' * v);
coeff = coeff - err(symbol) * v / normalizationfactor; % Weight update rule of NLMS
end
% Append new decision to decision feedback
if obj.dfe_order(1) > 0
%shift up one index
d_(2:end) = d_(1:end-1);
%replace 1st index with current estimation
d_(1) = d_hat(symbol);
end
if mod(sample,100) == 1 && showviz
a2.XData = 1:2*numel(y);
a2.YData = repelem(y, 2);
a3.XData = 1:2*numel(d_hat);
a3.YData = repelem(d_hat, 2);
a4.Value = sample;
c.YData = obj.e;
drawnow;
end
obj.error(epoch,symbol) = err(symbol) * err(symbol)'; % Instantaneous square error
end
end
obj.e = coeff(1:obj.ffe_order);
obj.b = coeff(obj.ffe_order+1:end);
end
end
end

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classdef FFE_FFDCAVG < handle
% Implementation of plain and simple FFE.
% 1) Training mode (stable performance when you use NLMS)
% 2) Decision directed mode
% Eq = FFE("epochs_tr",5,"epochs_dd",5,"len_tr",4096*2,"mu_dd",1e-4,"mu_tr",0,"order",25,"sps",2,"decide",0);
properties
sps % usually 2
order
e
error
len_tr
mu_tr
epochs_tr
mu_dd
epochs_dd
mu_buff
constellation
decide
end
methods
function obj = FFE_FFDCAVG(options)
arguments(Input)
options.sps = 2;
options.order = 15;
options.len_tr = 4096;
options.mu_tr = 0;
options.epochs_tr = 5;
options.mu_dd = 1e-5;
options.epochs_dd = 5;
options.mu_buff = 0;
options.decide = false;
end
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
obj.e = zeros(obj.order,1);
obj.error = 0;
end
function [X] = process(obj, X, D)
% actual processing of the signal (steps 1. - 3.)
% 1 normalize RMS
X = X.normalize("mode","rms");
obj.constellation = unique(D.signal);
% Training Mode
training = 1;
showviz = 0;
obj.equalize(X.signal, D.signal,obj.mu_tr,obj.epochs_tr,obj.len_tr,training,showviz);
% Decision Directed Mode
N = X.length;
training = 0;
showviz = 0;
[signal,decision]=obj.equalize(X.signal, D.signal,obj.mu_dd,obj.epochs_dd,N,training,showviz);
% Output Signal
if obj.decide
X.signal = decision;
else
X.signal = signal;
end
X.fs = D.fs; %change sampling frequency of outgoing signal from fdac e.g. 2 sps to symbol spaced = fsym
lbdesc = [num2str(obj.order),' tap FFE'];
X = X.logbookentry(lbdesc); % append to logbook
end
function [y,d_hat] = equalize(obj,x,d,mio,epochs,N,training,showviz)
arguments
obj
x
d
mio
epochs
N
training
showviz
end
x = [zeros(floor(obj.order/2),1); x; zeros(obj.order,1)];
if showviz
f = figure(111);
subplot(2,2,1:2);
hold on
a = scatter(1:numel(x),x,1,'.');
a2 = scatter(1,1,1,'.');
a3 = scatter(1,1,2,'.');
a4 = xline(1);
ylim([-3 3])
xlim([0 length(x)]);
% subplot(2,2,3)
% dplot = x(1:1+500);
% b = scatter(1:numel(dplot),dplot,5,'x');
% xline(1)
% xline(obj.order)
% ylim([-3 3])
% xlim([0 500]);
subplot(2,2,3:4)
c = stem(obj.e);
ylim([-1 1])
drawnow
end
for epoch = 1 : epochs
symbol = 0;
err_buffer = zeros(numel(obj.constellation),112);
dc_err = zeros(numel(obj.constellation),1);
dc_sto = NaN(numel(obj.constellation),N);
for sample = 1 : obj.sps : N
symbol = symbol+1;
U = x(obj.order+sample-1:-1:sample);
y(symbol,1) = obj.e.' * U; % Calculating output of LMS __ * |
if training
[~,symbol_idx] = min(abs(d(symbol) - obj.constellation)); % decision for closest constellation point
d_hat(symbol,1) = d(symbol);
else
always_correct_decision = 0;
if always_correct_decision
[~,symbol_idx] = min(abs(d(symbol) - obj.constellation)); % decision for closest constellation point
else
[~,symbol_idx] = min(abs(y(symbol) - obj.constellation)); % decision for closest constellation point
end
d_hat(symbol,1) = obj.constellation(symbol_idx);
end
err(symbol) = y(symbol) - d_hat(symbol); % Instantaneous error
if 1
%use buffer for dc-error
err_buffer(symbol_idx,1) = err(symbol);
err_buffer(symbol_idx,:) = circshift(err_buffer(symbol_idx,:),1);
dc_sto(symbol_idx,symbol) = obj.mu_buff*mean(err_buffer(symbol_idx,:));
y(symbol) = y(symbol) - obj.mu_buff * mean(err_buffer(symbol_idx,:));
else
%or use 1+alpha*D as adaptive error
dc_err(symbol_idx) = dc_err(symbol_idx) + obj.mu_buff * err(symbol);
dc_sto(symbol_idx,symbol) = dc_err(symbol_idx);
y(symbol) = y(symbol) - dc_err(symbol_idx);
end
if training
[~,symbol_idx] = min(abs(d(symbol) - obj.constellation)); % decision for closest constellation point
d_hat(symbol,1) = d(symbol);
else
[~,symbol_idx] = min(abs(y(symbol) - obj.constellation)); % decision for closest constellation point
d_hat(symbol,1) = obj.constellation(symbol_idx);
end
err(symbol) = y(symbol) - d_hat(symbol); % Instantaneous error
if mio ~= 0
obj.e = obj.e - (mio * err(symbol) * U) ; % Weight update rule of LMS
else
normalizationfactor = (U.' * U);
obj.e = obj.e - err(symbol) * U / normalizationfactor; % Weight update rule of NLMS
end
if mod(sample,100) == 1 && showviz
a2.XData = 1:2*numel(y);
a2.YData = repelem(y, 2);
a3.XData = 1:2*numel(d_hat);
a3.YData = repelem(d_hat, 2);
a4.Value = sample;
% b.YData = x(symbol:symbol+500);
c.YData = obj.e;
drawnow;
end
obj.error(epoch,symbol) = err(symbol) * err(symbol)'; % Instantaneous square error
end
end
end
end
end

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classdef FFE_adaptive_decision < handle
% Implementation of plain and simple FFE.
% 1) Training mode (stable performance when you use NLMS)
% 2) Decision directed mode
% Eq = FFE("epochs_tr",5,"epochs_dd",5,"len_tr",4096*2,"mu_dd",1e-4,"mu_tr",0,"order",25,"sps",2,"decide",0);
properties
sps % usually 2
order
e
error
len_tr
mu_tr
epochs_tr
mu_dd
epochs_dd
buffer_length
constellation
decide
end
methods
function obj = FFE_adaptive_decision(options)
arguments(Input)
options.sps = 2;
options.order = 15;
options.len_tr = 4096;
options.mu_tr = 0;
options.epochs_tr = 5;
options.mu_dd = 1e-5;
options.epochs_dd = 5;
options.buffer_length = 100;
options.decide = false;
end
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
obj.e = zeros(obj.order,1);
obj.error = 0;
end
function [X] = process(obj, X, D)
% actual processing of the signal (steps 1. - 3.)
% 1 normalize RMS
X = X.normalize("mode","rms");
obj.constellation = unique(D.signal);
% Training Mode
training = 1;
showviz = 0;
obj.equalize(X.signal, D.signal,obj.mu_tr,obj.epochs_tr,obj.len_tr,training,showviz);
% Decision Directed Mode
N = X.length;
training = 0;
showviz = 0;
[signal,decision]=obj.equalize(X.signal, D.signal,obj.mu_dd,obj.epochs_dd,N,training,showviz);
% Output Signal
if obj.decide
X.signal = decision;
else
X.signal = signal;
end
X.fs = D.fs; %change sampling frequency of outgoing signal from fdac e.g. 2 sps to symbol spaced = fsym
lbdesc = [num2str(obj.order),' tap FFE'];
X = X.logbookentry(lbdesc); % append to logbook
end
function [y,d_hat] = equalize(obj,x,d,mio,epochs,N,training,showviz)
arguments
obj
x
d
mio
epochs
N
training
showviz
end
x = [zeros(floor(obj.order/2),1); x; zeros(obj.order,1)];
for epoch = 1 : epochs
symbol = 0;
% y_buffer = zeros(numel(obj.constellation),500);
y_buffer = repmat(obj.constellation,1,obj.buffer_length);
for sample = 1 : obj.sps : N
symbol = symbol+1;
U = x(obj.order+sample-1:-1:sample);
y(symbol,1) = obj.e.' * U; % Calculating output of LMS __ * |
if training
[~,symbol_idx] = min(abs(d(symbol) - obj.constellation)); % decision for closest constellation point
d_hat(symbol,1) = d(symbol);
else
y_buffer(y_buffer==0) = NaN;
adap_constellation = mean(y_buffer,2,"omitnan");
[~,symbol_idx] = min(abs(y(symbol) - adap_constellation)); % decision for closest constellation point
d_hat(symbol,1) = obj.constellation(symbol_idx);
end
y_buffer(symbol_idx,1) = y(symbol);
y_buffer(symbol_idx,:) = circshift(y_buffer(symbol_idx,:),1);
err(symbol) = y(symbol) - d_hat(symbol); % Instantaneous error
if mio ~= 0
obj.e = obj.e - (mio * err(symbol) * U) ; % Weight update rule of LMS
else
normalizationfactor = (U.' * U);
obj.e = obj.e - err(symbol) * U / normalizationfactor; % Weight update rule of NLMS
end
obj.error(epoch,symbol) = err(symbol) * err(symbol)'; % Instantaneous square error
end
end
end
end
end

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classdef VNLE < handle
% Implementation of plain and simple FFE.
% 1) Training mode (stable performance when you use NLMS)
% 2) Decision directed mode
% Eq = VNLE("epochs_tr",5,"epochs_dd",5,"len_tr",4096*2,"mu_dd",[0.0004 0.0005 0.0006],"mu_tr",0,"order",[25,2,2],"sps",2,"decide",1);
% Somehow it is not possible to use only 1 nonlinear order
properties
sps % usually 2
order
e
error
len_tr
mu_tr
epochs_tr
mu_dd
epochs_dd
constellation
decide
x_norm
ce
ie2
ie3
end
methods
function obj = VNLE(options)
arguments(Input)
options.sps = 2;
options.order = [15,2,2];
options.len_tr = 4096;
options.mu_tr = 0;
options.epochs_tr = 5;
options.mu_dd = 1e-5;
options.epochs_dd = 5;
options.decide = false;
end
fn = fieldnames(options);
for n = 1:numel(fn)
obj.(fn{n}) = options.(fn{n});
end
obj.error = 0;
end
function [X] = process(obj, X, D)
% actual processing of the signal (steps 1. - 3.)
% 1 normalize RMS
X = X.normalize("mode","rms");
obj.constellation = unique(D.signal);
obj.x_norm = obj.calcPowerNormalization(X.signal);
obj.ce = obj.calcVNLEMemoryLength(obj.order);
[obj.ie2,obj.ie3] = obj.calcIndiceVectors(obj.order);
obj.e = zeros( sum(obj.ce) ,1);
% Training Mode
training = 1;
showviz = 0;
obj.equalize(X.signal, D.signal,obj.mu_tr,obj.epochs_tr,obj.len_tr,training,showviz);
% Decision Directed Mode
N = X.length;
training = 0;
showviz = 0;
[signal,decision]=obj.equalize(X.signal, D.signal,obj.mu_dd,obj.epochs_dd,N,training,showviz);
% Output Signal
if obj.decide
X.signal = decision;
else
X.signal = signal;
end
X.fs = D.fs; %change sampling frequency of outgoing signal from fdac e.g. 2 sps to symbol spaced = fsym
lbdesc = [num2str(obj.order),' tap FFE'];
X = X.logbookentry(lbdesc); % append to logbook
end
function [y,d_hat] = equalize(obj,x,d,mu,epochs,N,training,showviz)
arguments
obj
x
d
mu
epochs
N
training
showviz
end
if all(mu == mu(1))
% mu = mu(1);
mu = diag(ones(1,sum(obj.ce))*mu(1));
else
mu = diag([ones(1,obj.ce(1))*mu(1) ...
ones(1,obj.ce(2))*mu(2) ...
ones(1,obj.ce(3))*mu(3) ]);
end
x = [zeros(floor(obj.order(1)/2),1); x; zeros(obj.order(1),1)];
if showviz
f = figure(111);
subplot(2,2,1:2);
hold on
a = scatter(1:numel(x),x,1,'.');
a2 = scatter(1,1,1,'.');
a3 = scatter(1,1,2,'.');
a4 = xline(1);
ylim([-3 3])
xlim([0 length(x)]);
subplot(2,2,3:4)
c = stem(obj.e);
ylim([-1 1])
drawnow
end
for epoch = 1 : epochs
symbol = 0;
for sample = 1 : obj.sps : N
symbol = symbol+1;
% x_in = x(obj.order(1)+sample+(obj.sps-1):-1:sample+obj.sps);
x_in = x(obj.order(1)+sample-1:-1:sample);
x_in = obj.calcVNLENonlinVecs(x_in,obj.ie2,obj.ie3,obj.order,obj.x_norm);
y(symbol,1) = obj.e.' * x_in; % Calculating output of LMS __ * |
if training
err(symbol) = y(symbol) - d(symbol); % Instantaneous error
else
[~,symbol_idx] = min(abs(y(symbol) - obj.constellation)); % decision for closest constellation point
d_hat(symbol,1) = obj.constellation(symbol_idx);
err(symbol) = y(symbol) - d_hat(symbol); % Instantaneous error
end
if ~all(mu==0,'all') %mu has not only zeros
obj.e = obj.e - (mu * err(symbol) * x_in) ; % Weight update rule of LMS
else
normalizationfactor = (x_in.' * x_in);
obj.e = obj.e - err(symbol) * x_in / normalizationfactor; % Weight update rule of NLMS
end
if mod(sample,100) == 1 && showviz
a2.XData = 1:2*numel(y);
a2.YData = repelem(y, 2);
a3.XData = 1:2*numel(d_hat);
a3.YData = repelem(d_hat, 2);
a4.Value = sample;
% b.YData = x(symbol:symbol+500);
c.YData = obj.e;
drawnow;
end
obj.error(epoch,symbol) = err(symbol) * err(symbol)'; % Instantaneous square error
end
end
end
%% Functions needed During Adaption
function x_in_vnle_format = calcVNLENonlinVecs(~,x_in_block,I_2,I_3,N_,norm_)
% These are the second and third order input signal products of the VNLE EQ
% h1 x_in(k-n1) + h2 x_in(k-n1)*x_in(k-n2) + h3 x_in(k-n1)*x_in(k-n2)*x_in(k-n3)
l1=length(x_in_block);
l2=length(I_2);
l3=length(I_3);
final_length = l1+l2+l3;
x_in_vnle_format = zeros(final_length,1);
idx = l1;
x_in_vnle_format(1:idx) = x_in_block;
if N_(2) > 0
delta_2 = round((N_(1)-N_(2)) / 2);
input_vec_se = x_in_block(delta_2:end) / norm_(2); %TODO normalization step
% Extract columns from I_2
col1 = input_vec_se(I_2(:,1));
col2 = input_vec_se(I_2(:,2));
x2 = col1 .* col2;
x_in_vnle_format(idx+1:idx+l2) = x2;
end
if N_(3) > 0
delta_3 = round((N_(1)-N_(3))/2);
input_vec_th = x_in_block(delta_3:end) / norm_(3);
% Extract columns from I_3
col1 = input_vec_th(I_3(:,1));
col2 = input_vec_th(I_3(:,2));
col3 = input_vec_th(I_3(:,3));
% Perform matrix multiplication
x3 = col1 .* col2 .* col3;
idx = idx+l2;
x_in_vnle_format(idx+1:idx+l3) = x3;
end
end
%% Functions needed for Preparation
function [C] = calcVNLEMemoryLength(~,N)
%calculates the memory length of VNLE
C = zeros(size(N));
for o = 1:numel(N)
switch o
case 1
C(o) = N(o);
case 2
C(o) = N(o)*(N(o)+1) / 2;
case 3
C(o) = N(o)*(N(o)+1)*(N(o)+2) / 6;
end
end
end
function [indvec2nd, indvec3rd] = calcIndiceVectors(~,N)
% Init vectors of 2nd and 3rd order coefficient indices ->
% yield combination with
indvec2nd=[];
indvec3rd=[];
for o = 2:numel(N)
n = N(o);
v = 1:n; % Ursprünglicher Vektor
row = 1;
% Schleifen zur Generierung des Indize Vektors
switch o
case 2
indvec2nd = zeros(n*(n+1)/2, o);
for i = 1:n
for j = i:n
indvec2nd(row, :) = [v(i) v(j)];
row = row + 1;
end
end
case 3
indvec3rd = zeros(n*(n+1)*(n+2)/6, 3);
for i = 1:n
for j = i:n
for k = j:n
indvec3rd(row, :) = [v(i) v(j) v(k)];
row = row + 1;
end
end
end
end
end
end
function powerNorm = calcPowerNormalization(~,v)
powerNorm(1) = sqrt(mean(abs(v ).^2));
powerNorm(2) = sqrt(mean(abs(v.^2).^2));
powerNorm(3) = sqrt(mean(abs(v.^3).^2));
end
end
end