tx_value = rand(1,1);
tx_index = quantise_value(tx_value, 0, 1, Nlevels);
tx_bits = dec2bin(tx_index, Nbits) - '0';
- tx_symbols = (-1 + 2*tx_bits) .* amps;
+ tx_symbols = (-1 + 2*tx_bits) .* amps;
% AWGN noise and phase/freq offset channel simulation
% 0.5 factor ensures var(noise) == variance , i.e. splits power between Re & Im
endfunction
-% gray codes with specified number of data an dparity bits. Soft
+% gray codes with specified number of data and parity bits. Soft
% decision decoding. Didn't really work out.
function valid_codewords = fuzzy_code_create(ndata,nparity)
bad_distance = 0;
for i=1:Nvalid
for k=i+1:Nvalid
- distance = sum(bitxor(valid_codewords(i,:), valid_codewords(k,:)))
+ distance = sum(bitxor(valid_codewords(i,:), valid_codewords(k,:)));
if distance < 2
bad_distance++;
end
tx_codeword = codewords(value+1,:);
endfunction
-function value = fuzzy_code_decode(codewords, rx_symbols)
+function [value, best_codeword] = fuzzy_code_decode(codewords, rx_symbols)
max_corr = 0;
value = 0;
[rows,cols] = size(codewords);
if (corr > max_corr)
max_corr = corr;
value = i-1;
+ best_codeword = codewords(i,:);
end
end
endfunction
-function set_codewords = fuzzy_code_create(ndata, nparity)
- Nbits = ndata + nparity;
- Nvalid = 2 .^ ndata;
- M = 2 .^ Nbits;
-
- codewords = dec2bin(0:(M-1), Nbits) - '0';
-
- set_codewords(1,:) = codewords(1,:);
-
- for i=1:Nvalid-1
-
- % measure distance from current set to all codewords
-
- for m=1:i
- printf("%d: ", m);
- for k=1:length(codewords);
- d(m,k) = sum(bitxor(set_codewords(m,:), codewords(k,:)));
- printf("%d ", d(m,k));
- end
- printf("\n");
- end
-
- % choose new codeword for set that has maximum distance from current set
-
- dmax = 0; best_cw = 1;
- for k=1:length(codewords);
- dmin = min(d(:,k));
- if dmin > dmax
- dmax = dmin;
- best_cw = k;
- end
- end
-
- printf("[%d %d]\n", dmax, best_cw);
- set_codewords(i+1,:) = codewords(best_cw,:)
- end
-
-endfunction
-
function sim_out = test_fuzzy_code(Ebvec, Ndata, Nparity, Ntrials)
Nbits = Ndata + Nparity;
variance = 1/EbNo;
- Terrs = 0; Tbits = 0;
+ Terrs = 0; Terrs_coded = 0; Tbits = 0;
+ Nsingle = Nsingle_corrected = 0;
qsignal = qnoise = 0;
for nn = 1:Ntrials
noise = sqrt(variance*0.5)*(randn(1,Nsymb) + j*randn(1,Nsymb));
rx_symbols = tx_symbols + noise;
- rx_index = fuzzy_code_decode(codewords, rx_symbols);
- rx_value = unquantise_value(rx_index, 0, 1, Nlevels);
+ % uncoded BER
+ rx_bits = rx_symbols > 0;
+ error_positions = xor(rx_bits(1:Ndata), tx_codeword(1:Ndata));
+ Nerrs = sum(error_positions);
+ Terrs += Nerrs;
+ Tbits += Ndata;
+
+ % decode and determine QSNR
+
+ [rx_index, rx_codeword] = fuzzy_code_decode(codewords, rx_symbols);
+ rx_value = unquantise_value(rx_index, 0, 1, Nlevels);
qsignal += tx_value*tx_value;
qnoise += (tx_value - rx_value) .^ 2;
sim_out.qnoise_log(ne,nn) = tx_value - rx_value;
+
+ % coded BER
+
+ error_positions = xor(rx_codeword(1:Ndata), tx_codeword(1:Ndata));
+ Nerrs_coded = sum(error_positions);
+ if Nerrs == 1
+ Nsingle++;
+ if Nerrs_coded == 0
+ Nsingle_corrected++;
+ end
+ end
+ Terrs_coded += Nerrs_coded;
+
end
+ sim_out.BERvec(ne) = Terrs/Tbits;
+ sim_out.BERvec_coded(ne) = Terrs_coded/Tbits;
+ sim_out.Nsingle(ne) = Nsingle;
+ sim_out.Nsingle_corrected(ne) = Nsingle_corrected;
+
sim_out.QSNRvec(ne) = 10*log10(qsignal/qnoise);
- printf("EbNo (dB): %3.2f QSNR (dB): %3.2f\n", EbNodB, sim_out.QSNRvec(ne));
+ printf("EbNo (dB): %3.2f Terrs: %6d BER %1.4f Terrs_coded: %6d BER_coded %1.4f QSNR (dB): %3.2f",
+ EbNodB, Terrs, Terrs/Tbits, Terrs_coded, Terrs_coded/Tbits, sim_out.QSNRvec(ne));
+ printf(" Nsingle: %d Nsingle_corrected: %d corrected: %3.1f\n", Nsingle, Nsingle_corrected, Nsingle_corrected*100/Nsingle);
end
endfunction
function compare_baseline_fuzzy
- Ebvec = 0:7;
- Ntrials = 1000;
- Nbits = 3; Nparity = 1;
+ Ebvec = 0:3;
+ Ntrials = 5000;
+ Nbits = 4; Nparity = 1;
- baseline = test_baseline_uncoded(Ebvec, Nbits, Ntrials);
+ baseline = test_baseline_uncoded(Ebvec, Nbits, Ntrials, 0, 0);
fuzzy = test_fuzzy_code(Ebvec, Nbits, Nparity, Ntrials);
figure(1);
hist(fuzzy.qnoise_log(4,:),50);
figure(4)
- plot(baseline.qnoise_log(1,1:250),'b;baseline;')
- hold on;
- plot(fuzzy.qnoise_log(1,1:250),'r;fuzzy;')
- hold off;
+ subplot(211)
+ plot(baseline.qnoise_log(4,1:250),'b;baseline;')
+ subplot(212)
+ plot(fuzzy.qnoise_log(4,1:250),'r;fuzzy;')
endfunction
% compare baseline and variable power schemes and make plots
baseline = test_baseline_uncoded(Ebvec, Nbits, Ntrials, 0, 0);
amps = [2 1.5 1.0 0.5 0.5];
av_pwr = (amps*amps')/length(amps);
- amps_norm = amps/sqrt(av_pwr)
+ amps_norm = amps/sqrt(av_pwr);
varpower = test_varpower(Ebvec, Nbits, Ntrials, amps_norm, 0);
figure(1);
function generate_varpower_error_files(EbNo, start_bit, end_bit, amps, error_file_name)
Fs = 25; % number of samples per second
- Nsec = 15; % seconds to simulate
+ Nsec = 3; % seconds to simulate
Ntrials = Fs*Nsec;
Nbits = end_bit - start_bit + 1;
bits_per_frame = 52;
varpower_errors = [];
for i=1:Ntrials
error_positions = varpower.error_log(Nbits*(i-1)+1:Nbits*i);
+
+ if 0
+ % reset single errors to tes effect of ideal single bit error correcting code
+ for i=1:7
+ st = 4*(i-1)+1
+ en = 4*i
+ if sum(error_positions(st:en)) == 1
+ error_positions(st:en) = 0;
+ end
+ end
+ for i=1:2
+ st = 7*4+3*(i-1)+1
+ en = 7*4+3*i
+ if sum(error_positions(st:en)) == 1
+ error_positions(st:en) = 0;
+ end
+ end
+ st = 7*4+3*2+1
+ en = 7*4+3*2+2
+ if sum(error_positions(st:en)) == 1
+ error_positions(st:en) = 0;
+ end
+ end
+
num_errors(i) = sum(error_positions);
varpower_errors = [varpower_errors zeros(1,start_bit-1) error_positions ...
zeros(1, bits_per_frame_rounded - Nbits - (start_bit-1))];
more off;
-generate_varpower_error_files(0, 17, 52, ones(1,36), "lsp_baseline_errors_0dB.bin")
-amps = [8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 8 4 2 8 4];
-generate_varpower_error_files(0, 17, 52, amps, "lsp_varpower_errors_0dB.bin")
+%generate_varpower_error_files(0, 17, 52, ones(1,36), "lsp_baseline_errors_0dB.bin")
+%amps = [1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1 1 ];
+%generate_varpower_error_files(0, 17, 52, amps, "lsp_varpower_errors_0dB.bin")
%compare_natural_nbit_plot
%compare_natural_gray_plot
%compare_baseline_varpower_plot
%compare_baseline_varpower_error_files
-%compare_baseline_fuzzy
+compare_baseline_fuzzy
%fuzzy_code_create(3,1)
projects / freetel-svn-tracking.git / commitdiff