Many changes for 400G DSP

Minimal Example
...

projects/IMDD_base_system/parameters.m

@@ -0,0 +1,46 @@
+% TX 
+    M               = 4;
+    fsym            = 180e9;
+    f_nyquist       = fsym/2;
+    apply_pulsef    = 0;
+    fdac            = 2*fsym;%256e9;
+    fadc            = 2*fsym;%256e9;
+    fdac            = 256e9;
+    fadc            = 256e9;
+    random_key      = 1;
+    db_precode      = 0;
+    emulate_precode = 0;
+    discard_precode = 0;
+    db_encode       = 0;
+    % duob_mode       = db_mode.db_emulate;
+    emulate_db = 1;
+    rcalpha         = 0.05;
+    kover           = 16;
+    vbias_rel       = 0.5;
+    u_pi            = 2.9;
+    vbias           = -vbias_rel*u_pi;
+    laser_wavelength    = 1310;
+    laser_linewidth     = 0;
+    tx_bw_nyquist   = 1.5;
+
+% Channel
+    link_length     = 1;
+
+% RX
+    rop = -8;
+    rx_bw_nyquist = 0.7;
+
+% EQ
+    eq_mode = equalizer_structure.vnle_pf_mlse;
+    ffe_order=[50,0,0];
+    vnle_order=[50,7,7];
+    dfe_order = [2 0 0];
+
+    len_tr = 4096*2;
+    mu_ffe = [0.0004 0.0004 0.0004];
+    mu_dfe = 0.0004;
+    mu_dc = 0.00;
+
+    dfe_ = sum(dfe_order)>0;
+
+