New MPI mitigation schemes // Duobinary // Start of FTN schemes
This commit is contained in:
Silas Oettinghaus
406
Classes/01_transmit/ChannelFreqResp.m
Normal file
406
Classes/01_transmit/ChannelFreqResp.m
Normal file
@@ -0,0 +1,406 @@
|
||||
classdef ChannelFreqResp < handle
|
||||
% Linear pre-compensation of Channel effects. This module has two modes:
|
||||
|
||||
% A) In acquire mode it sends a real OFDM singal with all subcarriers assigned in
|
||||
% order to acquire later the system's frequency response after the
|
||||
% signal passed the system...
|
||||
% ChannelFreqResp.SendOFDM
|
||||
|
||||
% B) In the "not acquire" mode it loads the frequency response generated by the freq_res module,
|
||||
% calculates the inverse frequency response with the right length matched
|
||||
% with the signal length and distorts the signal before tranmission
|
||||
% give channel indices for measure mode
|
||||
|
||||
%TYPICAL FLOW:
|
||||
|
||||
% referencesignal = ChannelFreqResp.buildOFDM()
|
||||
|
||||
% referencesignal -> SYSTEM -> measuredsignal
|
||||
|
||||
% ChannelFreqResp.estimate(measuredsignal)
|
||||
|
||||
properties(Access=public)
|
||||
Nacq
|
||||
Navg
|
||||
Ncp
|
||||
|
||||
f_ref %fs of transmitted dmt sig
|
||||
f_observe %fs of the observed signal
|
||||
|
||||
symlen
|
||||
seqlen
|
||||
|
||||
refsig
|
||||
H
|
||||
H_all
|
||||
H_apply
|
||||
|
||||
Nfft
|
||||
df
|
||||
faxis
|
||||
end
|
||||
|
||||
methods (Access=public)
|
||||
|
||||
function obj = ChannelFreqResp(options)
|
||||
%NAME Construct an instance of this class
|
||||
% Detailed explanation goes here
|
||||
|
||||
arguments
|
||||
options.Nacq = 4096;
|
||||
options.Navg = 30;
|
||||
options.Ncp = 100;
|
||||
options.f_ref;
|
||||
options.f_observe;
|
||||
end
|
||||
|
||||
%
|
||||
fn = fieldnames(options);
|
||||
for n = 1:numel(fn)
|
||||
try
|
||||
obj.(fn{n}) = options.(fn{n});
|
||||
end
|
||||
end
|
||||
|
||||
obj.Nfft = 2*obj.Nacq + 1 ;
|
||||
obj.df = obj.f_ref/obj.Nfft ; % calculate frequency grid
|
||||
obj.faxis = (0:obj.Nfft-1)*obj.df ;
|
||||
|
||||
end
|
||||
|
||||
function output = buildOFDM(obj)
|
||||
% generate OFDM or DMT signal that is send over the channel
|
||||
|
||||
obj.symlen = (obj.Nacq*2+obj.Ncp+1);
|
||||
|
||||
obj.seqlen = obj.symlen*obj.Navg;
|
||||
|
||||
obj.refsig = obj.genRNDDMT(15)';
|
||||
|
||||
obj.refsig = Informationsignal(obj.refsig,"fs",obj.f_ref);
|
||||
|
||||
output = obj.refsig;
|
||||
|
||||
end
|
||||
|
||||
function output = estimate(obj, data_in, options)
|
||||
arguments
|
||||
obj
|
||||
data_in
|
||||
options.save logical = false
|
||||
options.savePath = "";
|
||||
options.fileName = "";
|
||||
end
|
||||
% use the transmitted DMT and the received DMT to get the transfer function
|
||||
|
||||
obj.Nfft = 2*obj.Nacq + 1 ;
|
||||
|
||||
%resample from fadc to fdac (fdac => fs of reference signal)
|
||||
data_in = data_in.resample("fs_out",obj.f_ref);
|
||||
|
||||
%est from dmt
|
||||
obj.H_all = obj.estHfromDMT(data_in.signal,obj.refsig.signal);
|
||||
|
||||
obj.H = mean(obj.H_all,1);
|
||||
|
||||
output = obj.H;
|
||||
|
||||
if options.save
|
||||
obj.save('fileName',options.fileName,'savePath',options.savePath);
|
||||
end
|
||||
|
||||
end
|
||||
|
||||
function Target = precomp(obj,Target,options)
|
||||
% apply the freq response
|
||||
arguments
|
||||
obj
|
||||
Target
|
||||
options.fileName = ''
|
||||
options.loadPath = ''
|
||||
options.maxampdb
|
||||
end
|
||||
|
||||
if isempty(obj.H)
|
||||
obj.load("fileName",options.fileName,"loadPath",options.loadPath);
|
||||
end
|
||||
|
||||
H_inv = 1./obj.H;
|
||||
|
||||
nH = find(~isnan(H_inv),1,'last'); %last value that is not nan
|
||||
H_inv(nH:end)=H_inv(nH); %replace everything after first NaN with the last non-NaN value
|
||||
|
||||
fstarget = Target.fs;
|
||||
|
||||
% Build new frequencie axis (with current fs)
|
||||
fnew = linspace(0,fstarget/2,length(Target)/2+1);
|
||||
fnew = fnew(2:end-1);
|
||||
|
||||
% Old frequency axis (should be much coarser)
|
||||
idx_old = find((obj.faxis > 0) .* (obj.faxis < fstarget/2)); %positions of all Frequencies smaller than fs/2
|
||||
int_fold = obj.faxis(idx_old); %old frequencies from 0 to fs/2
|
||||
|
||||
idx_new = find(fnew <= int_fold(end)); %positions of all Frequencies smaller than fs/2
|
||||
int_fnew = fnew(idx_new);%new frequencies from 0 to fs/2
|
||||
|
||||
% interpolate the frequency response that had a coarse frequency resolution (e.g. 256 bins) to the current frequency resolution (e.g. 21843 bins)
|
||||
iH = interp1(int_fold, real(H_inv(idx_old)) ,fnew, 'linear') + 1i*interp1(int_fold, imag(H_inv(idx_old)) ,fnew, 'linear');
|
||||
|
||||
% set all NaN values to the fist/ last non-NaN value
|
||||
nH = find(~isnan(iH),1,'first');
|
||||
iH(1:nH)=iH(nH);
|
||||
nH = find(~isnan(iH),1,'last');
|
||||
iH(nH:end) =iH(nH);
|
||||
|
||||
%smoothing takes time and sometimes the result looks odd,
|
||||
%however the performance is most of the time better
|
||||
smoothing = 1;
|
||||
if smoothing
|
||||
iH = smooth(fnew,iH,0.1,'loess')';
|
||||
end
|
||||
|
||||
% multiply the complex frequency responce with the phase
|
||||
% angle (-pi,pi) at lowest frequency
|
||||
iH = iH.*exp(-1j*angle(iH(1))); % to be checked (<- not from silas, so what needs to be checked?)
|
||||
|
||||
% Phase difference between lowest and hiughest frequency
|
||||
% component -> but what is this for? dPhase is not used...
|
||||
noncausal = 0;
|
||||
if noncausal
|
||||
dPhase = angle(iH(end))-angle(iH(1));
|
||||
end
|
||||
|
||||
% normalize complex freq. resp. by magnitude at the first
|
||||
% five frequencies -> should be the vaue at f=0=DC component?
|
||||
iH = iH./mean(abs(iH(1:100))); %why 1:5??
|
||||
|
||||
% set maximum amplification
|
||||
% set als values higher than hmax to hmax and keep the
|
||||
% phase information by multiplication with respective
|
||||
% corresponding phase angles
|
||||
maxamp_lin = 10^(options.maxampdb/20);
|
||||
|
||||
iH(abs(iH)>maxamp_lin) = maxamp_lin.*exp(1j*angle(iH(abs(iH)>maxamp_lin)));
|
||||
|
||||
% it could be helpful to clip at linear 1 (=to keep comp from attenuating the signal)
|
||||
% iH(abs(iH)<1) = 1.*exp(1j*angle(iH(abs(iH)<1)));
|
||||
|
||||
if 0
|
||||
figure(7);hold on;plot(fnew,20*log10(abs(iH)))
|
||||
end
|
||||
H_inv = [iH(1) iH fliplr(conj(iH)) conj(iH(1))];
|
||||
|
||||
obj.H_apply = H_inv;
|
||||
|
||||
Target.signal = real((ifft( ( fft(real( Target.signal )) .* H_inv' ) )));
|
||||
|
||||
|
||||
end
|
||||
|
||||
function plot(obj)
|
||||
|
||||
figure(55551);
|
||||
clf;
|
||||
|
||||
Havg = obj.H;
|
||||
|
||||
%1)
|
||||
subplot(4,1,1);hold all;box on;title('Magnitude Freq. Response');
|
||||
plot(obj.faxis/1e9, 20*log10(abs(obj.H_all)),'linewidth',0.1,'LineStyle','-','Color','#808080') ;
|
||||
xlim([0.2 .5*max(obj.faxis)*1e-9]);
|
||||
plot(obj.faxis/1e9, 20*log10(abs(Havg)),'LineWidth',2);
|
||||
grid on;
|
||||
|
||||
%2)
|
||||
subplot(4,1,2); hold all; box on; title('Phase Freq. Response');
|
||||
plot(obj.faxis/1e9, (angle(obj.H_all)),'linewidth',0.1,'LineStyle','-','Color','#808080') ;
|
||||
plot(obj.faxis/1e9, (angle(Havg)),'LineWidth',2) ;
|
||||
xlim([0.2 .5*max(obj.faxis)*1e-9]);
|
||||
grid on;
|
||||
|
||||
%normalize / remove attenuation
|
||||
Havg = Havg./mean(Havg(2:10));
|
||||
|
||||
%3)
|
||||
subplot(4,1,3); hold all; box on; title('Inverse Magnitude Freq. Response');
|
||||
plot(obj.faxis/1e9, 20*log10(abs(1./Havg)),"LineWidth",2,"Color",[0.3467 0.5360 0.6907]) ;
|
||||
xlim([0.2 .5*max(obj.faxis)*1e-9]); grid on;
|
||||
ylim([-1 15]);
|
||||
hold on;
|
||||
yline(3,'LineWidth',2,'LineStyle','--');
|
||||
|
||||
%4)
|
||||
subplot(4,1,4); hold all; box on; title('Inverse Phase Freq. Response');
|
||||
plot(obj.faxis/1e9, (angle(1./Havg)),"LineWidth",2,"Color",[0.3467 0.5360 0.6907]) ;
|
||||
xlim([0.2 .5*max(obj.faxis)*1e-9]); grid on;
|
||||
|
||||
|
||||
end
|
||||
|
||||
function save(obj,options)
|
||||
arguments
|
||||
obj
|
||||
options.fileName = ''
|
||||
options.savePath = ''
|
||||
end
|
||||
|
||||
% Check if the fileName was provided
|
||||
if isempty(char(options.fileName))
|
||||
% If no file name is provided, prompt the user to enter a file name
|
||||
[options.fileName, filePath] = uiputfile('*.mat', 'Save As');
|
||||
|
||||
% If the user cancels the dialog, fileName and filePath will be 0
|
||||
if isequal(options.fileName, 0) || isequal(filePath, 0)
|
||||
disp('Save operation cancelled.');
|
||||
return;
|
||||
end
|
||||
|
||||
% Update the savePath with the directory chosen by the user
|
||||
options.savePath = filePath;
|
||||
end
|
||||
|
||||
% Check if the savePath was provided
|
||||
if isempty(char(options.savePath))
|
||||
% If no path is provided, open a UI window to select the path
|
||||
options.savePath = uigetdir('', 'Select a folder to save the file');
|
||||
|
||||
% If the user cancels the dialog, savePath will be 0
|
||||
if options.savePath == 0
|
||||
disp('Save operation cancelled.');
|
||||
return;
|
||||
end
|
||||
else
|
||||
% If a path is provided, validate it
|
||||
if ~isfolder(options.savePath)
|
||||
error('The specified path does not exist.');
|
||||
end
|
||||
end
|
||||
|
||||
% Construct the full file path
|
||||
fullFileName = fullfile(options.savePath, options.fileName);
|
||||
|
||||
% Save the data to the specified file
|
||||
save(fullFileName, 'obj');
|
||||
fprintf('Frequency response information successfully saved to %s\n', fullFileName);
|
||||
|
||||
end
|
||||
|
||||
function data = load(obj, options)
|
||||
% Function to load data from a specified file and path.
|
||||
arguments
|
||||
obj
|
||||
options.fileName = ''
|
||||
options.loadPath = ''
|
||||
end
|
||||
|
||||
% Check if the fileName was provided
|
||||
if isempty(char(options.fileName))
|
||||
% If no file name is provided, open a UI window to select the file
|
||||
[options.fileName, options.loadPath] = uigetfile('*.mat', 'Select a file to load');
|
||||
|
||||
% If the user cancels the dialog, fileName and loadPath will be 0
|
||||
if isequal(options.fileName, 0) || isequal(options.loadPath, 0)
|
||||
disp('Load operation cancelled.');
|
||||
data = [];
|
||||
return;
|
||||
end
|
||||
end
|
||||
|
||||
% If loadPath is not provided or empty, use the current folder
|
||||
if isempty(char(options.loadPath))
|
||||
options.loadPath = pwd;
|
||||
else
|
||||
% Validate the path if provided
|
||||
if ~isfolder(options.loadPath)
|
||||
error('The specified path does not exist.');
|
||||
end
|
||||
end
|
||||
|
||||
% Construct the full file path
|
||||
fullFileName = fullfile(options.loadPath, options.fileName);
|
||||
|
||||
% Check if the file exists
|
||||
if ~isfile(fullFileName)
|
||||
fullFileName = fullfile(options.loadPath, [char(options.fileName),'.mat']);
|
||||
if ~isfile(fullFileName)
|
||||
error('The specified file does not exist.');
|
||||
end
|
||||
end
|
||||
|
||||
% Load the data from the specified file
|
||||
loadedData = load(fullFileName);
|
||||
|
||||
% Replace whole obj here.. is this save or unsave?!
|
||||
fn = fieldnames(loadedData.obj);
|
||||
for n = 1:numel(fn)
|
||||
try
|
||||
obj.(fn{n}) = loadedData.obj.(fn{n});
|
||||
end
|
||||
end
|
||||
|
||||
fprintf('Frequency response information successfully loaded from %s\n', fullFileName);
|
||||
end
|
||||
|
||||
end
|
||||
|
||||
methods (Access=private)
|
||||
% Cant be seen from outside! So put all your functions here that can/
|
||||
% shall not be called from outside
|
||||
|
||||
function rOFDM = genRNDDMT(obj,randkey)
|
||||
|
||||
rOFDM = NaN(1,(2*obj.Nacq+obj.Ncp+1)*obj.Navg);
|
||||
|
||||
s = RandStream('mt19937ar','Seed',randkey,'NormalTransform','Polar');
|
||||
|
||||
ref = 2 * round(rand(s,obj.Nacq, obj.Navg)) - 1 ; % Navg Random BPSK sequences
|
||||
|
||||
ofdm = [ones(1, obj.Navg) ; ref ; conj(ref(end:-1:1,:)) ] ; % DMT
|
||||
|
||||
ofdm = ifft(ofdm) ; % Navg real OFDM sequences
|
||||
|
||||
ofdm = [ofdm(end-obj.Ncp+1 : end, :) ; ofdm] ; % Add cyclic prefix
|
||||
|
||||
rOFDM = reshape(ofdm, 1, size(ofdm,1)*size(ofdm,2)) ;
|
||||
|
||||
rOFDM = rOFDM./max(abs(rOFDM(:)));
|
||||
|
||||
end
|
||||
|
||||
function [rH] = estHfromDMT(obj, data_in, ref_in)
|
||||
|
||||
%! Dont (circ)shift the signal here as this would remove the phase information!
|
||||
%tested with a butterworth filter this exactly reconstructs the
|
||||
%phase and the magnitude. However, the option is here
|
||||
estimatephase = 1;
|
||||
|
||||
if ~estimatephase
|
||||
% 0. cross-correlate the received signal with its reference to extract the periods
|
||||
corr = abs(ifft( fft(data_in(1:length(ref_in))).* conj(fft(ref_in)) )) ;
|
||||
|
||||
% find max
|
||||
[~, peak] = max(corr) ;
|
||||
peak=max(1,peak-1);
|
||||
|
||||
data_in = circshift(data_in,-peak) ;
|
||||
%Y = data_in(peak:peak+(Nfft+obj.Ncp)*obj.Navg-1) ;
|
||||
end
|
||||
|
||||
% 1. Reshape signal to a matrix to support noise averaging
|
||||
Nfft = 2*obj.Nacq + 1 ;
|
||||
|
||||
Y = reshape(data_in, Nfft+obj.Ncp, obj.Navg).' ;
|
||||
|
||||
X = reshape(ref_in, Nfft + obj.Ncp, obj.Navg).' ;
|
||||
|
||||
% 2. Remove cyclic prefix and apply FFT transformation
|
||||
Y = fft(Y(:, obj.Ncp+1 : obj.Ncp + Nfft), [], 2) ;
|
||||
X = fft(X(:, obj.Ncp+1 : obj.Ncp + Nfft), [], 2) ;
|
||||
|
||||
% 4. Caclulate the frequency response using H = Y/X
|
||||
rH = Y./X ;
|
||||
|
||||
end
|
||||
|
||||
end
|
||||
end
|
||||
@@ -24,7 +24,9 @@ classdef PAMmapper
|
||||
|
||||
if isa(signal_in,'Signal')
|
||||
signal_in.signal = obj.map_(signal_in.signal);
|
||||
signal_in = signal_in.normalize("mode","rms");
|
||||
|
||||
% signal_in = signal_in.normalize("mode","rms");
|
||||
|
||||
signal_in = signal_in.logbookentry();
|
||||
out = signal_in;
|
||||
else
|
||||
@@ -42,7 +44,7 @@ classdef PAMmapper
|
||||
function pam_sig = map_(obj,bitpattern)
|
||||
|
||||
switch obj.M
|
||||
case 1
|
||||
case 2
|
||||
% 2-ASK: BPSK / OOK
|
||||
pam_sig=bitpattern(:,1);
|
||||
|
||||
@@ -87,6 +89,7 @@ classdef PAMmapper
|
||||
end
|
||||
|
||||
pam_sig = pam_sig/sqrt(21);
|
||||
|
||||
case 16
|
||||
% 16-ASK:
|
||||
x1 = bitpattern(:,1);
|
||||
|
||||
@@ -9,6 +9,8 @@ classdef PAMsource
|
||||
fsym
|
||||
randkey
|
||||
|
||||
db_precode
|
||||
|
||||
mrds_code
|
||||
mrds_blocklength
|
||||
|
||||
@@ -33,6 +35,8 @@ classdef PAMsource
|
||||
options.fsym = 112e9;
|
||||
options.randkey = 0;
|
||||
|
||||
options.db_precode = 0;
|
||||
|
||||
options.mrds_code = 0;
|
||||
options.mrds_blocklength = 512;
|
||||
|
||||
@@ -90,6 +94,11 @@ classdef PAMsource
|
||||
|
||||
symbols = PAMmapper(obj.M,0).map(bits);
|
||||
symbols.fs = obj.fsym;
|
||||
|
||||
if obj.db_precode
|
||||
symbols = Duobinary().precode(symbols);
|
||||
symbols = Duobinary().encode(symbols);
|
||||
end
|
||||
|
||||
if obj.mrds_code
|
||||
symbols = MRDS_coding("blocklength",obj.mrds_blocklength).encode(symbols);
|
||||
|
||||
Reference in New Issue
Block a user