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- improved TX

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- added TX windowing
- added RX

git-svn-id: http://moon:8086/svn/matlab/trunk@3 801c6759-fa7c-4059-a304-17956f83a07c
This commit is contained in:
jens
2014-07-26 18:34:33 +00:00
parent d5d5df21f9
commit 2a04c6b44c
3 changed files with 371 additions and 73 deletions
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ofdm/ofdm_rx.m
+126
View File
@@ -0,0 +1,126 @@
% function ofdm_sync(x, nsym, ngrd)
% Example: ofdm_sync(x, 1152, 128)
function ofdm_rx(x, offset, nsym_soll, ngrd)
% Init
fa = 48000;
fc = fa/4;
F1 = 750;
F2 = 2250;
F3 = 3000;
close all;
do_evaluate = 1;
alpha = 0.05;
x = real(x);
% Detection
display('Sync detection');
nsym_ist = nsym_soll;
xi = zeros(ngrd, 1);
range_max = 24;
range_min = 4;
range_forget = 0.5;
range = range_max;
err = 0;
k = 0;
kk = 1;
remain = length(x);
progress_ival = 1;
progress_last = -1;
nfft = nsym_soll-ngrd
bin_c = fix(nfft*fc/fa)+1
bin_f1 = fix(nfft*(fc+F1)/fa)+1
bin_f2 = fix(nfft*(fc+F2)/fa)+1
bin_f3 = fix(nfft*(fc+F3)/fa)+1
k_fft = 3/sqrt(nfft);
phi_c_last = 0;
phi_f1_last = 0;
phi_f2_last = 0;
phi_f3_last = 0;
while remain > 2*nsym_ist,
xsym = x(offset+k*nsym_ist+1:offset+k*nsym_ist+nsym_ist+range);
[xcor, imax, jmax, xi] = xcc(xsym, nsym_ist, ngrd, -range, range, -range, range, xi);
remain = remain - (length(offset+k*nsym_ist+1:offset+k*nsym_ist+nsym_ist+range));
err = -imax + jmax;
offset = offset + imax;
nsym_ist = max(round(nsym_ist + err), ngrd)
sl_offset(kk) = offset;
sl_err(kk) = err;
sl_nsym_ist(kk) = nsym_ist;
range = min(max(fix(range + abs(err) - range_forget), range_min), range_max);
progress = round(100*(length(x)-remain)/length(x));
if (progress ~= progress_last)
progress_last = progress_last + progress_ival;
progress = progress
end;
if (do_evaluate == 1)
X0 = k_fft*fft(xsym(1:nsym_ist-ngrd), nfft);
phi_c(kk) = (1-alpha)*phi_c_last + alpha*angle(X0(bin_c));
phi_f1(kk) = (1-alpha)*phi_f1_last + alpha*angle(X0(bin_f1));
phi_f2(kk) = (1-alpha)*phi_f2_last + alpha*angle(X0(bin_f2));
phi_f3(kk) = (1-alpha)*phi_f3_last + alpha*angle(X0(bin_f3));
phi_c_last = phi_c(kk);
phi_f1_last = phi_f1(kk);
phi_f2_last = phi_f2(kk);
phi_f3_last = phi_f3(kk);
%pause;
end;
k = k + 1;
kk = kk + 1;
end;
% Result
display('Results:');
offset_stddev = sqrt(var(sl_offset))
err_mean = mean(sl_err)
nsym_ist_mean = mean(nsym_ist)
% Diagrams
figure;
plot(1:length(sl_offset), sl_offset); title('offset'); legend('offset'); grid;
figure;
subplot(2,1,1)
plot(1:length(sl_err), sl_err); title('error'); legend('error'); grid;
subplot(2,1,2)
plot(1:length(sl_nsym_ist), sl_nsym_ist, 1:length(sl_nsym_ist), nsym_soll*ones(size(sl_nsym_ist))); title('Tracking'); legend('nsym_{ist}', 'nsym_{soll}'); grid;
figure
plot(1:length(phi_c), phi_c, 1:length(phi_f1), phi_f1, 1:length(phi_f2), phi_f2, 1:length(phi_f3), phi_f3); grid; legend('phi_{c}', 'phi_{f1}', 'phi_{f2}', 'phi_{f3}'); title('Phase');
% custom function
% Correlation
function [ccm, imax, jmax, xo] = xcc(x, Ns, Ng, i_low, i_high, j_low, j_high, xi)
Nu = Ns - Ng;
off = length(xi);
xo = x(length(x)-off+1:length(x));
xs = [xi' x']';
ccm = 0;
imax = 0;
jmax = 0;
for i_off=i_low:i_high,
ii = off+i_off+1:off+Ng+i_off;
xm_i = mean(xs(ii));
xi = xs(ii)-xm_i;
var_i = var(xi);
for j_off=j_low:j_high,
jj = off+Nu+j_off+1:off+Nu+Ng+j_off;
xm_j = mean(xs(jj));
xj = xs(jj) - xm_j;
var_j = var(xj);
cc = sum(xi.*xj)./sqrt(var_i*var_j);
if (cc > ccm)
imax = i_off;
jmax = j_off;
ccm = cc;
end;
end;
end;
ofdm/ofdm_tx.m
+235 -73
View File
@@ -1,9 +1,9 @@
% function ofdm_tx(N_data)
function yv = ofdm_tx(N_data)
% function ofdm_tx(N_frames)
function [yv xv] = ofdm_tx(N_frames)
j = sqrt(-1);
WORK_BANDPASS = 1;
do_evaluate = 0;
WITH_DATA = 0;
WITH_FREQ_REF = 1;
WITH_TIME_REF = 1;
% Params
fa = 48000;
@@ -12,25 +12,81 @@ F1 = 750;
F2 = 2250;
F3 = 3000;
N_Carrier = 226;
M_qam = 64;
N_lp = 301;
TSym = 21.3330E-3
TGrd = 5.333E-3
TFrm = TSym+TGrd
NGrd = round(TGrd*fa)
NSym = round(TSym*fa)
NFrm = round(TFrm*fa)
N_fft = NSym
SPEC_OCC_4k5 = 1;
SPEC_OCC_5k0 = 2;
SPEC_OCC_9k0 = 3;
SPEC_OCC_10k = 4;
SPEC_OCC_18k = 5;
SPEC_OCC_20k = 6;
bin_c = fix(N_fft*fc/fa)+1;
bin_f1 = fix(N_fft*(fc+F1)/fa)+1;
bin_f2 = fix(N_fft*(fc+F2)/fa)+1;
bin_f3 = fix(N_fft*(fc+F3)/fa)+1;
DRM_MODE_A = 1;
DRM_MODE_B = 2;
DRM_MODE_C = 3;
DRM_MODE_D = 4;
DRM_MODE_E = 5;
ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_4k5) = struct('kmin', 2, 'kmax', 102);
ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_5k0) = struct('kmin', 2, 'kmax', 114);
ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_9k0) = struct('kmin', -102, 'kmax', 102);
ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_10k) = struct('kmin', -114, 'kmax', 114);
ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_18k) = struct('kmin', - 98, 'kmax', 314);
ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_20k) = struct('kmin', -110, 'kmax', 350);
ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_4k5) = struct('kmin', 1, 'kmax', 91);
ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_5k0) = struct('kmin', 1, 'kmax', 103);
ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_9k0) = struct('kmin', - 91, 'kmax', 91);
ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_10k) = struct('kmin', -103, 'kmax', 103);
ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_18k) = struct('kmin', - 87, 'kmax', 279);
ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_20k) = struct('kmin', - 99, 'kmax', 311);
ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_4k5) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_5k0) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_9k0) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_10k) = struct('kmin', - 69, 'kmax', 69);
ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_18k) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_20k) = struct('kmin', - 67, 'kmax', 213);
ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_4k5) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_5k0) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_9k0) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_10k) = struct('kmin', - 44, 'kmax', 44);
ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_18k) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_20k) = struct('kmin', - 43, 'kmax', 135);
ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_4k5) = struct('kmin', -106, 'kmax', 106);
ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_5k0) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_9k0) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_10k) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_18k) = struct('kmin', 0, 'kmax', 0);
ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_20k) = struct('kmin', 0, 'kmax', 0);
ofdm_params_drm(DRM_MODE_A) = struct('nu', 288, 'ng', 32, 'nspf', 15);
ofdm_params_drm(DRM_MODE_B) = struct('nu', 256, 'ng', 64, 'nspf', 15);
ofdm_params_drm(DRM_MODE_C) = struct('nu', 176, 'ng', 64, 'nspf', 20);
ofdm_params_drm(DRM_MODE_D) = struct('nu', 112, 'ng', 88, 'nspf', 24);
ofdm_params_drm(DRM_MODE_E) = struct('nu', 27, 'ng', 3, 'nspf', 40);
ofdm_params = ofdm_params_drm(DRM_MODE_B)
ofdm_spec_occ = ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_10k)
N_Carrier = 226;
M_qam = 4;
N_lp = 301;
T = 4/fa;
Tu = ofdm_params.nu * T
Tg = ofdm_params.ng * T
Ts = Tu+Tg
Ng = round(Tg*fa)
Nu = round(Tu*fa)
Ns = round(Ts*fa)
N_fft = Nu
SubCarrierspacing_HZ = fa/N_fft
% TX window
[txwin Nt] = txwin_eval(Nu, Ng, 0.05);
% Source
qlut = qamtable(M_qam);
s = round(M_qam*rand(N_data,1)+0.5);
% Band pass for transmission
f_lp = N_Carrier*fa/N_fft
@@ -39,64 +95,50 @@ hbp = hbp/sum(hbp.^2).*Hanning(N_lp)';
hlp = sinc((-(N_lp-1)/2:(N_lp-1)/2)*f_lp/fa);
hlp = hlp/sum(hlp.^2).*Hanning(N_lp)';
t = 1;
if (WORK_BANDPASS == 1)
bin_range = N_fft/4-N_Carrier/2:N_fft/4+N_Carrier/2;
else
bin_range = 1:N_Carrier;
end;
k_fft = 2*sqrt(N_fft);
xv = [];
xt = zeros(1, Nt);
N_bins = length(bin_range);
for k=1:N_data/N_bins,
% DC
X = zeros(N_fft,1);
X(1) = 0;
for m=1:N_bins,
% Data
X(bin_range(m)) = qlut(s(t));
t = t + 1;
end;
% Additional carrier
if (WORK_BANDPASS == 1)
X(bin_c) = 1.0;
X(bin_f1) = 1.0 + j*1.0;
X(bin_f2) = 1.0 - j*1.0;
X(bin_f3) = -1.0 + j*1.0;
end;
% Make conj. symmetric in F => real in T
X(N_fft:-1:N_fft/2+1) = conj(X(2:N_fft/2+1));
% Modulate
x = ifft(X);
xgrd = x(NSym-NGrd+1:NSym);
xt = [xgrd' x']';
xv((k-1)*(NFrm)+1:k*(NFrm)) = xt;
for k=1:N_frames
for s=0:ofdm_params.nspf-1,
if (do_evaluate == 1)
xf = fft(xt(NGrd+1:NSym+NGrd), N_fft);
plot(xf, '+'); grid;
pause;
end;
X = zeros(N_fft,1);
% Data
if WITH_DATA == 1
data_i = c2i(N_fft, ofdm_spec_occ.kmin:1:ofdm_spec_occ.kmax);
X(data_i) = 0.20*qlut(round(M_qam*rand(1, length(data_i))+0.5));
end;
% X(78) = 0.20*qlut(round(M_qam*rand(1, 1)+0.5));
if WITH_FREQ_REF == 1
[ref_i ref_p ref_a] = getRefFreq(N_fft, DRM_MODE_B, s);
X(ref_i) = 0.20*ref_a.*exp(-2*pi*i*ref_p/1024);
end;
if (s==0) & (WITH_TIME_REF == 1)
[ref_i ref_p ref_a] = getRefTime(N_fft, DRM_MODE_B);
X(ref_i) = 0.20*ref_a.*exp(-2*pi*i*ref_p/1024);
end;
% X(1) = 0.2;
% Modulate
xu = k_fft*ifft(X, N_fft)';
xs = [xu(Nu-Ng+1:Nu) xu xu(1:Nt)] .* txwin;
xs(1:Nt) = xs(1:Nt) + xt(1:Nt);
xt = xs(Ng+Nu+1:Ng+Nu+Nt);
xv = [xv xs(1:Ng+Nu)];
end;
end;
k_fft = 0.3333*sqrt(N_fft);
% Modulate on carrier
yc = 0.5*exp(-i*2*pi.*(0:length(xv)-1)*fc/fa) .* filter(hlp,1,xv);
yv = real(yc) + imag(yc);
% Pulse shape
if (WORK_BANDPASS == 1)
yv = real(filter(hbp,1,k_fft*xv));
% yv = k_fft*xv;
else
yc = cos(2*pi*(0:length(xv)-1)*fc/fa);
yF1 = 1.0/N_fft*cos(2*pi*(0:length(xv)-1)*F1/fa);
yF2 = 1.0/N_fft*cos(2*pi*(0:length(xv)-1)*F2/fa);
yF3 = 1.0/N_fft*cos(2*pi*(0:length(xv)-1)*F3/fa);
yv = yc.*(0.025 + filter(hlp,1,k_fft*xv) + yF1 + yF2 + yF3);
end;
xv = xv';
yv = yv';
% Output
close all;
@@ -104,4 +146,124 @@ close all;
figure;
freqz(hlp);
wavwrite(yv,fa,16,'yv.wav')
wavwrite(0.9*yv,fa,16,'yv.wav')
wavwrite(0.9*[real(xv) imag(xv)],fa,16,'xv.wav')
function index = c2i(N_fft, carriers)
ri = [];
ri = [ri find(carriers == 0)];
carriers(ri) = [];
index = mod(carriers, 1024) + 1;
function [ref_i ref_p ref_a] = getRefFreq(N_fft, drmMode, s)
ref_A_c = [18 54 72];
ref_A_p = [205 836 215];
ref_A_a = sqrt(2)*ones(1,3);
ref_B_c = [16 48 64];
ref_B_p = [331 651 555];
ref_B_a = sqrt(2)*ones(1,3);
ref_C_c = [11 33 44];
ref_C_p = [214 392 242];
ref_C_a = sqrt(2)*ones(1,3);
ref_D_c = [ 7 21 28];
ref_D_p = [788 1014 332];
ref_D_a = sqrt(2)*ones(1,3);
ref_E_c = [];
ref_E_p = [];
ref_E_a = [];
switch drmMode
case 1
ref_i = c2i(N_fft, ref_A_c);
ref_p = ref_A_p;
ref_a = ref_A_a;
case 2
ref_i = c2i(N_fft, ref_B_c);
ref_p = ref_B_p;
ref_a = ref_B_a;
case 3
ref_i = c2i(N_fft, ref_C_c);
ref_p = ref_C_p;
ref_a = ref_C_a;
case 4
ref_i = c2i(N_fft, ref_D_c);
ref_p = ref_D_p;
ref_a = ref_D_a;
case 5
ref_i = c2i(N_fft, ref_E_c);
ref_p = ref_E_p;
ref_a = ref_E_a;
end;
function [ref_i ref_p ref_a] = getRefTime(N_fft, drmMode)
ref_B_c = [14 18 20 24 26 32 36 42 44 49 50 54 56 62 66 68];
ref_B_p = [304 108 620 192 704 44 432 588 844 651 651 460 460 944 940 428];
ref_B_a = sqrt(2)*ones(1,16);
switch drmMode
case 1
ref_i = [];
ref_p = [];
ref_a = [];
case 2
ref_i = c2i(N_fft, ref_B_c);
ref_p = ref_B_p;
ref_a = ref_B_a;
case 3
ref_i = [];
ref_p = [];
ref_a = [];
case 4
ref_i = [];
ref_p = [];
ref_a = [];
case 5
ref_i = [];
ref_p = [];
ref_a = [];
end;
function [ref_i ref_p ref_a] = getRefGain(N_fft, spec_occ, drmMode, s)
switch drmMode
case 1
ref_c = [];
ref_p = [];
ref_a = [];
case 2
ref_c = 1 + 2*mod(s,3)+6*(spec_occ.kmin:1:spec_occ.kmax);
ref_i = c2i(N_fft, ref_c);
ref_p = ref_B_p;
ref_a = sqrt(2)*ones(1,length(ref_i));
case 3
ref_c = [];
ref_p = [];
ref_a = [];
case 4
ref_c = [];
ref_p = [];
ref_a = [];
case 5
ref_c = [];
ref_p = [];
ref_a = [];
end;
ofdm/txwin_eval.m
+10
View File
@@ -0,0 +1,10 @@
function [p Nt] = txwin_eval(Nu, Ng, Alpha)
Nfft = Nu; % FFT size
CP = Ng; % Nb. samples in Cyclic Prefix
%Alpha = 1/32; % RX Alpha
Nt = 2*round(Nfft*Alpha/2); % Nb. samples in taper region
p = 1/2*(1+cos(pi*[-Nt+1/2:Nt-1/2]/Nt)); % Raised-Cosine in TD
p = [p(1:Nt), ones(1,Nfft+CP-Nt), p(Nt+1:2*Nt)]; % Add ones in middle