changing the prototypes of the ldpc encoder functions to harmonize more with standard

adding ldpctest encoder, decoder and ldpctest to CMakeLists.txt
activating the TCL LDPC decoder in the LDPC testbench but only works for largest blocksize 8448 for now.

cmake_targets/CMakeLists.txt

@@ -1147,7 +1147,13 @@ set(PHY_POLARSRC
 )
 set(PHY_TURBOIF
   ${OPENAIR1_DIR}/PHY/CODING/coding_load.c
-)
+  )
+set(PHY_LDPCSRC
+  ${OPENAIR1_DIR}/PHY/CODING/nrLDPC_decoder/nrLDPC_decoder.c
+  ${OPENAIR1_DIR}/PHY/CODING/nrLDPC_encoder/ldpc_encoder.c
+  ${OPENAIR1_DIR}/PHY/CODING/nrLDPC_encoder/ldpc_encoder2.c
+  ${OPENAIR1_DIR}/PHY/CODING/nrLDPC_encoder/ldpc_generate_coefficient.c
+  )
 
 add_library(coding MODULE ${PHY_TURBOSRC} )
 
@@ -1300,6 +1306,7 @@ set(PHY_SRC_UE
   ${OPENAIR1_DIR}/PHY/TOOLS/time_meas.c
   ${OPENAIR1_DIR}/PHY/TOOLS/lut.c
   ${PHY_POLARSRC}
+  ${PHY_LDPCSRC}
   )
 
   set(PHY_NR_UE_SRC
@@ -1337,6 +1344,7 @@ set(PHY_SRC_UE
   ${OPENAIR1_DIR}/PHY/TOOLS/lut.c
   ${OPENAIR1_DIR}/PHY/INIT/nr_init_ue.c
   ${PHY_POLARSRC}
+  ${PHY_LDPCSRC}
   )
 
 
@@ -2541,6 +2549,9 @@ target_link_libraries (dlsim_tm4
 add_executable(polartest ${OPENAIR1_DIR}/PHY/CODING/TESTBENCH/polartest.c)
 target_link_libraries(polartest m SIMU PHY PHY_NR -lm ${ATLAS_LIBRARIES})
 
+add_executable(ldpctest  ${OPENAIR1_DIR}/PHY/CODING/TESTBENCH/ldpctest.c)
+target_link_libraries(ldpctest m SIMU PHY PHY_NR ${ATLAS_LIBRARIES})
+
 foreach(myExe dlsim dlsim_tm7 ulsim pbchsim scansim mbmssim pdcchsim pucchsim prachsim syncsim)
 
   add_executable(${myExe}

openair1/PHY/CODING/TESTBENCH/ldpctest.c

@@ -25,8 +25,18 @@
 #include <string.h>
 
 #include "SIMULATION/TOOLS/sim.h"
+#include "PHY/CODING/nrLDPC_encoder/defs.h"
+#include "PHY/CODING/nrLDPC_decoder/nrLDPC_decoder.h"
 
+#define MAX_NUM_DLSCH_SEGMENTS 16
 
+#ifndef malloc16
+#  ifdef __AVX2__
+#    define malloc16(x) memalign(32,x)
+#  else
+#    define malloc16(x) memalign(16,x)
+#  endif
+#endif
 
 // 4-bit quantizer
 char quantize4bit(double D,double x)
@@ -62,11 +72,11 @@ char quantize(double D,double x,unsigned char B)
 #define MAX_BLOCK_LENGTH 8448
 
 int test_ldpc(short No_iteration,
-              int nom_rate,
-              int denom_rate,
+              //int nom_rate,
+              //int denom_rate,
               double SNR,
               unsigned char qbits,
-              short block_length,
+              unsigned short block_length,
               unsigned int ntrials,
               unsigned int *errors,
               unsigned int *crc_misses)
@@ -85,15 +95,16 @@ int test_ldpc(short No_iteration,
   double *modulated_input;
   char *channel_output_fixed;
   unsigned int i,j,trial=0;
-  short BG,Zc,Kb,nrows,ncols;
-  int no_punctured_columns,removed_bit;
+  short BG,Zc,Kb;
+  //short nrows,ncols;
+  //int no_punctured_columns,removed_bit;
   int i1;
   //Table of possible lifting sizes
   short lift_size[51]= {2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,18,20,22,24,26,28,30,32,36,40,44,48,52,56,60,64,72,80,88,96,104,112,120,128,144,160,176,192,208,224,240,256,288,320,352,384};
   int n_segments=8;
 
   t_nrLDPC_dec_params decParams;
-  int n_iter;
+  //int n_iter;
 
   *errors=0;
   *crc_misses=0;
@@ -107,7 +118,9 @@ int test_ldpc(short No_iteration,
   modulated_input = (double *)malloc(sizeof(double) * 68*384);
   channel_output  = (double *)malloc(sizeof(double) * 68*384);
   channel_output_fixed  = (char *)malloc16(sizeof(char) * 68*384);
-  estimated_output = (unsigned char*) malloc16(sizeof(unsigned char) * block_length/8);
+  estimated_output = (unsigned char*) malloc16(sizeof(unsigned char) * block_length);
+
+  memset(channel_output_fixed,0,sizeof(char) * 68*384);
 
   reset_meas(&time);
   reset_meas(&time_optim);
@@ -124,18 +137,18 @@ int test_ldpc(short No_iteration,
   }
 
   //determine number of bits in codeword
-  //if (block_length>3840)
+  if ((block_length>3840) && (block_length <= MAX_BLOCK_LENGTH))
   {
     BG=1;
     Kb = 22;
-    nrows=46; //parity check bits
-    ncols=22; //info bits
+    //nrows=46; //parity check bits
+    //ncols=22; //info bits
   }
-  /*else if (block_length<=3840)
+  else if (block_length<=3840) 
   {
     BG=2;
-    nrows=42; //parity check bits
-    ncols=10; // info bits
+    //nrows=42; //parity check bits
+    //ncols=10; // info bits
 
     if (block_length>640)
       Kb = 10;
@@ -145,11 +158,14 @@ int test_ldpc(short No_iteration,
       Kb = 8;
     else
       Kb = 6;
-      }*/
-
+  }
+  else {
+    printf("block_length %d not supported\n",block_length);
+    exit(-1);
+  }
+  
   //find minimum value in all sets of lifting size
   Zc=0;
-
   for (i1=0; i1 < 51; i1++)
   {
     if (lift_size[i1] >= (double) block_length/Kb)
@@ -161,11 +177,11 @@ int test_ldpc(short No_iteration,
   }
 
   printf("ldpc_test: block_length %d, BG %d, Zc %d, Kb %d\n",block_length,BG, Zc, Kb);
-  no_punctured_columns=(int)((nrows-2)*Zc+block_length-block_length*(1/((float)nom_rate/(float)denom_rate)))/Zc;
+  //no_punctured_columns=(int)((nrows-2)*Zc+block_length-block_length*(1/((float)nom_rate/(float)denom_rate)))/Zc;
   //  printf("puncture:%d\n",no_punctured_columns);
-  removed_bit=(nrows-no_punctured_columns-2) * Zc+block_length-(int)(block_length/((float)nom_rate/(float)denom_rate));
+  //removed_bit=(nrows-no_punctured_columns-2) * Zc+block_length-(int)(block_length/((float)nom_rate/(float)denom_rate));
   if (ntrials==0)
-    ldpc_encoder_orig(test_input[0],channel_input[0], block_length, nom_rate, denom_rate, 1);
+    ldpc_encoder_orig(test_input[0],channel_input[0], block_length, BG, 1);
   
   for (trial=0; trial < ntrials; trial++)
   {
@@ -173,20 +189,20 @@ int test_ldpc(short No_iteration,
     //// encoder
     start_meas(&time);
     for(j=0;j<n_segments;j++) {
-      ldpc_encoder_orig(test_input[j], channel_input[j],block_length,nom_rate,denom_rate,0);
+      ldpc_encoder_orig(test_input[j], channel_input[j],block_length,BG,0);
     }
     stop_meas(&time);
 
     start_meas(&time_optim);
-    ldpc_encoder_optim_8seg(test_input,channel_input_optim,block_length,nom_rate,denom_rate,n_segments,&tinput,&tprep,&tparity,&toutput);
+    ldpc_encoder_optim_8seg(test_input,channel_input_optim,block_length,BG,n_segments,&tinput,&tprep,&tparity,&toutput);
     /*for(j=0;j<n_segments;j++) {
-      ldpc_encoder_optim(test_input[j],channel_input_optim[j],block_length,nom_rate,denom_rate,&tinput,&tprep,&tparity,&toutput);
+      ldpc_encoder_optim(test_input[j],channel_input_optim[j],block_length,BG,&tinput,&tprep,&tparity,&toutput);
       }*/
     stop_meas(&time_optim);
     
     if (ntrials==1)    
       for (j=0;j<n_segments;j++)
-	for (i = 0; i < block_length+(nrows-no_punctured_columns) * Zc - removed_bit; i++)
+	for (i = 0; i < 3*block_length; i++)
 	  if (channel_input[j][i]!=channel_input_optim[j][i]) {
 	    printf("differ in seg %d pos %d (%d,%d)\n",j,i,channel_input[j][i],channel_input_optim[j][i]);
 	    return (-1);
@@ -198,10 +214,7 @@ int test_ldpc(short No_iteration,
     //printf("channel_input[%d]=%d\n",i,channel_input[i]);
     //printf("%d ",channel_input[i]);
 
-    //if ((BG==2) && (Zc==128||Zc==256))
-    if (0)
-    {
-      for (i = 2*Zc; i < (Kb+nrows-no_punctured_columns) * Zc-removed_bit; i++)
+      for (i = 2*Zc; i < 3*block_length; i++)
       {
 #ifdef DEBUG_CODER
         if ((i&0xf)==0)
@@ -209,7 +222,7 @@ int test_ldpc(short No_iteration,
 #endif
 
         if (channel_input[0][i-2*Zc]==0)
-          modulated_input[i]=1/sqrt(2);  //QPSK
+          modulated_input[i]=1/sqrt(2);  //BPSK
         else
           modulated_input[i]=-1/sqrt(2);
 
@@ -218,16 +231,12 @@ int test_ldpc(short No_iteration,
 	//printf("llr[%d]=%d\n",i,channel_output_fixed[i]);
       }
 
-      //for (i=(Kb+nrows) * Zc-5;i<(Kb+nrows) * Zc;i++)
-      //{
-      //  printf("channel_input[%d]=%d\n",i,channel_input[i]);
-      //printf("%lf %d\n",channel_output[i], channel_output_fixed[i]);
-      //printf("v[%d]=%lf\n",i,modulated_input[i]);}
-#ifdef DEBUG_CODER
-      printf("\n");
-      exit(-1);
-#endif
-
+      /*
+	the LDPC decoder supports several rates and the input has to be adapted accordingly (by padding with zeros to the next lower supported rate). Moreover, the first 2*Z LLRs are zero (since they are punctured and not transmitted) then you have the LLRs corresponding to the systematic bits. After that come the filler bits, the encoder uses 0 for the filler bits hence for the decoder you need to put 127 (max LLR for bit 0) at their place. Then come the LLRs corresponding to the punctured bits followed by zeros to pad for the supported decoder rate.
+      */
+      for (i=0;i<2*Zc;i++) 
+	channel_output_fixed[i] = 0;
+      
       decParams.BG=BG;
       decParams.Z=Zc;
       decParams.R=13;
@@ -236,9 +245,9 @@ int test_ldpc(short No_iteration,
 
       // decode the sequence
       // decoder supports BG2, Z=128 & 256
-      //esimated_output=ldpc_decoder(channel_output_fixed, block_length, No_iteration, (double)((float)nom_rate/(float)denom_rate));
+      //estimated_output=ldpc_decoder(channel_output_fixed, block_length, No_iteration, (double)((float)nom_rate/(float)denom_rate));
 
-      nrLDPC_decoder(&decParams, channel_output_fixed, estimated_output, NULL);
+      nrLDPC_decoder(&decParams, (int8_t*) channel_output_fixed, (int8_t*) estimated_output, NULL);
 
       //for (i=(Kb+nrows) * Zc-5;i<(Kb+nrows) * Zc;i++)
       //  printf("esimated_output[%d]=%d\n",i,esimated_output[i]);
@@ -248,15 +257,12 @@ int test_ldpc(short No_iteration,
       {
         if (estimated_output[i] != test_input[0][i])
         {
-	  //printf("error pos %d (%d, %d)\n",i,estimated_output[i],test_input[i]);
+	  printf("error pos %d (%d, %d)\n",i,estimated_output[i],test_input[0][i]);
           *errors = (*errors) + 1;
           break;
         }
       }
 
-    }
-    /*else if (trial==0)
-      printf("decoder is not supported\n");*/
   }
 
   for(j=0;j<MAX_NUM_DLSCH_SEGMENTS;j++) {
@@ -284,8 +290,8 @@ int main(int argc, char *argv[])
   short block_length=576; // decoder supports length: 1201 -> 1280, 2401 -> 2560
   short No_iteration=25;
   //double rate=0.333;
-  int nom_rate=1;
-  int denom_rate=3;
+  //int nom_rate=1;
+  //int denom_rate=3;
   double SNR0=-2.0,SNR,SNR_lin;
   unsigned char qbits=4;
   unsigned int decoded_errors[100]; // initiate the size of matrix equivalent to size of SNR
@@ -295,21 +301,13 @@ int main(int argc, char *argv[])
 
   randominit(0);
 
-  while ((c = getopt (argc, argv, "q:r:s:l:n:d:")) != -1)
+  while ((c = getopt (argc, argv, "q:s:l:n:h")) != -1)
     switch (c)
     {
       case 'q':
         qbits = atoi(optarg);
         break;
 
-      case 'r':
-        nom_rate = atoi(optarg);
-        break;
-
-      case 'd':
-        denom_rate = atoi(optarg);
-        break;
-
       case 'l':
         block_length = atoi(optarg);
         break;
@@ -323,21 +321,25 @@ int main(int argc, char *argv[])
         break;
 
       default:
-        abort ();
+      case 'h':
+	printf("usage ldpctest -h -l blocklength -n n_trials -s SNR\n");
+        exit(0);
     }
 
-  printf("the decoder supports BG2, Kb=10, Z=128 & 256\n");
-  printf(" range of blocklength: 1201 -> 1280, 2401 -> 2560\n");
+  //printf("the decoder supports BG2, Kb=10, Z=128 & 256\n");
+  //printf(" range of blocklength: 1201 -> 1280, 2401 -> 2560\n");
+  //printf("rate: %d/%d\n",nom_rate,denom_rate);
   printf("block length %d: \n", block_length);
-  printf("rate: %d/%d\n",nom_rate,denom_rate);
+  printf("n_trials %d: \n", n_trials);
+  printf("SNR0 %f: \n", SNR0);
 
   //for (block_length=8;block_length<=MAX_BLOCK_LENGTH;block_length+=8)
   for (SNR=SNR0;SNR<SNR0+1.0;SNR+=1.0)
   {
     SNR_lin = pow(10,SNR/10);
     decoded_errors[i]=test_ldpc(No_iteration,
-                                nom_rate,
-                                denom_rate,
+                                //nom_rate,
+                                //denom_rate,
                                 SNR_lin,   // noise standard deviation
                                 qbits,
                                 block_length,   // block length bytes

openair1/PHY/CODING/nrLDPC_encoder/defs.h

@@ -31,6 +31,18 @@
 
 #include "PHY/TOOLS/time_meas.h"
 
+/*ldpc_encoder.c*/
+int encode_parity_check_part_orig(unsigned char *c,unsigned char *d, short BG,short Zc,short Kb,short block_length);
+
+/*ldpc_encoder2.c*/
+void encode_parity_check_part_optim(uint8_t *c,uint8_t *d, short BG,short Zc,short Kb);
+int ldpc_encoder_optim(unsigned char *test_input,unsigned char *channel_input,short block_length,short BG,time_stats_t *tinput,time_stats_t *tprep,time_stats_t *tparity,time_stats_t *toutput);
+int ldpc_encoder_optim_8seg(unsigned char **test_input,unsigned char **channel_input,short block_length,short BG,int n_segments,time_stats_t *tinput,time_stats_t *tprep,time_stats_t *tparity,time_stats_t *toutput);
+
+/*ldpc_generate_coefficient.c*/
+int ldpc_encoder_orig(unsigned char *test_input,unsigned char *channel_input,short block_length,short BG,unsigned char gen_code);
+
+/*
 int encode_parity_check_part(unsigned char *c,unsigned char *d, short BG,short Zc,short Kb);
 int encode_parity_check_part_orig(unsigned char *c,unsigned char *d, short BG,short Zc,short Kb,short block_length);
 int ldpc_encoder(unsigned char *test_input,unsigned char *channel_input,short block_length, double rate);
@@ -38,4 +50,4 @@ int ldpc_encoder_orig(unsigned char *test_input,unsigned char *channel_input,sho
 int ldpc_encoder_multi_segment(unsigned char **test_input,unsigned char **channel_input,short block_length,double rate,uint8_t n_segments);
 int ldpc_encoder_optim(unsigned char *test_input,unsigned char *channel_input,short block_length,int nom_rate,int denom_rate,time_stats_t *tinput,time_stats_t *tprep,time_stats_t *tparity,time_stats_t *toutput);
 int ldpc_encoder_optim_8seg(unsigned char **test_input,unsigned char **channel_input,short block_length,int nom_rate,int denom_rate,int n_segments,time_stats_t *tinput,time_stats_t *tprep,time_stats_t *tparity,time_stats_t *toutput);
-
+*/

openair1/PHY/CODING/nrLDPC_encoder/ldpc_encoder2.c

@@ -198,10 +198,10 @@ void encode_parity_check_part_optim(uint8_t *c,uint8_t *d, short BG,short Zc,sho
 }
 
 
-int ldpc_encoder_optim(unsigned char *test_input,unsigned char *channel_input,short block_length,int nom_rate,int denom_rate,time_stats_t *tinput,time_stats_t *tprep,time_stats_t *tparity,time_stats_t *toutput)
+int ldpc_encoder_optim(unsigned char *test_input,unsigned char *channel_input,short block_length,short BG,time_stats_t *tinput,time_stats_t *tprep,time_stats_t *tparity,time_stats_t *toutput)
 {
 
-  short BG,Zc,Kb,nrows,ncols;
+  short Kb,Zc,nrows,ncols;
   int i,i1;
   int no_punctured_columns,removed_bit;
 
@@ -211,16 +211,14 @@ int ldpc_encoder_optim(unsigned char *test_input,unsigned char *channel_input,sh
   int simd_size;
 
   //determine number of bits in codeword
-  //if (block_length>3840)
+  if (BG==1)
     {
-      BG=1;
       Kb = 22;
       nrows=46; //parity check bits
       ncols=22; //info bits
     }
-    /*else if (block_length<=3840)
+    else if (BG==2)
     {
-      BG=2;
       nrows=42; //parity check bits
       ncols=10; // info bits
       
@@ -232,7 +230,7 @@ int ldpc_encoder_optim(unsigned char *test_input,unsigned char *channel_input,sh
       Kb = 8;
     else
       Kb = 6;
-      }*/
+    }
 
   //find minimum value in all sets of lifting size
   Zc=0;
@@ -315,10 +313,10 @@ int ldpc_encoder_optim(unsigned char *test_input,unsigned char *channel_input,sh
   return 0;
 }
 
-int ldpc_encoder_optim_8seg(unsigned char **test_input,unsigned char **channel_input,short block_length,int nom_rate,int denom_rate,int n_segments,time_stats_t *tinput,time_stats_t *tprep,time_stats_t *tparity,time_stats_t *toutput)
+int ldpc_encoder_optim_8seg(unsigned char **test_input,unsigned char **channel_input,short block_length,short BG,int n_segments,time_stats_t *tinput,time_stats_t *tprep,time_stats_t *tparity,time_stats_t *toutput)
 {
 
-  short BG,Zc,Kb,nrows,ncols;
+  short Kb,Zc,nrows,ncols;
   int i,i1,j;
   int no_punctured_columns,removed_bit;
   //Table of possible lifting sizes
@@ -345,16 +343,14 @@ int ldpc_encoder_optim_8seg(unsigned char **test_input,unsigned char **channel_i
   AssertFatal(n_segments>0&&n_segments<=8,"0 < n_segments %d <= 8\n",n_segments);
 
   //determine number of bits in codeword
-  //if (block_length>3840)
+  if (BG==1)
     {
-      BG=1;
       Kb = 22;
       nrows=46; //parity check bits
       ncols=22; //info bits
     }
-    /*else if (block_length<=3840)
+    else if (BG==2)
     {
-      BG=2;
       nrows=42; //parity check bits
       ncols=10; // info bits
       
@@ -366,7 +362,7 @@ int ldpc_encoder_optim_8seg(unsigned char **test_input,unsigned char **channel_i
       Kb = 8;
     else
       Kb = 6;
-      }*/
+    }
 
   //find minimum value in all sets of lifting size
   Zc=0;

openair1/PHY/CODING/nrLDPC_encoder/ldpc_generate_coefficient.c

@@ -361,13 +361,13 @@ short *choose_generator_matrix(short BG,short Zc)
   return Gen_shift_values;
 }
 
-int ldpc_encoder_orig(unsigned char *test_input,unsigned char *channel_input,short block_length,int nom_rate,int denom_rate,unsigned char gen_code)
+int ldpc_encoder_orig(unsigned char *test_input,unsigned char *channel_input,short block_length,short BG,unsigned char gen_code)
 {
   unsigned char c[22*384]; //padded input, unpacked, max size
   unsigned char d[68*384]; //coded output, unpacked, max size
   unsigned char channel_temp,temp;
   short *Gen_shift_values, *no_shift_values, *pointer_shift_values;
-  short BG,Zc,Kb,nrows,ncols;
+  short Zc,Kb,nrows,ncols;
   int i,i1,i2,i3,i4,i5,temp_prime,var;
   int no_punctured_columns,removed_bit;
   //Table of possible lifting sizes
@@ -378,16 +378,14 @@ int ldpc_encoder_orig(unsigned char *test_input,unsigned char *channel_input,sho
   int indlist2[1000];
 
   //determine number of bits in codeword
-  //if (block_length>3840)
+  if (BG==1)
   {
-    BG=1;
     Kb = 22;
     nrows=46; //parity check bits
     ncols=22; //info bits
   }
-  /*else if (block_length<=3840)
+  else if (BG==2)
   {
-    BG=2;
     nrows=42;  //parity check bits
     ncols=10;  // info bits
 
@@ -399,7 +397,7 @@ int ldpc_encoder_orig(unsigned char *test_input,unsigned char *channel_input,sho
       Kb = 8;
     else
       Kb = 6;
-      }*/
+  }
 
   //find minimum value in all sets of lifting size
   Zc=0;
@@ -417,6 +415,8 @@ int ldpc_encoder_orig(unsigned char *test_input,unsigned char *channel_input,sho
     return(-1);
   }
 
+  int K = ncols*Zc;
+
   Gen_shift_values=choose_generator_matrix(BG,Zc);
   if (Gen_shift_values==NULL) {
     printf("ldpc_encoder_orig: could not find generator matrix\n");
@@ -438,9 +438,15 @@ int ldpc_encoder_orig(unsigned char *test_input,unsigned char *channel_input,sho
   }
   
   no_punctured_columns=(int)((nrows-2)*Zc+block_length-block_length*3)/Zc;
+  //nrows - no_punctured_columns = 2 +2*block_length/Zc
   removed_bit=(nrows-no_punctured_columns-2) * Zc+block_length-(block_length*3);
+  // ((nrows-no_punctured_columns) * Zc-removed_bit) =
+  // 2Zc + 2*block_length
   //printf("%d\n",no_punctured_columns);
   //printf("%d\n",removed_bit);
+  //printf("%d\n",nrows-no_punctured_columns);
+  //printf("%d\n",((nrows-no_punctured_columns) * Zc-removed_bit));
+  
   // unpack input
   memset(c,0,sizeof(unsigned char) * ncols * Zc);
   memset(d,0,sizeof(unsigned char) * nrows * Zc);
@@ -608,8 +614,8 @@ int ldpc_encoder_orig(unsigned char *test_input,unsigned char *channel_input,sho
   }
 
   // information part and puncture columns
-  memcpy(&channel_input[0], &c[2*Zc], (block_length-2*Zc)*sizeof(unsigned char));
-  memcpy(&channel_input[block_length-2*Zc], &d[0], ((nrows-no_punctured_columns) * Zc-removed_bit)*sizeof(unsigned char));
+  memcpy(&channel_input[0], &c[2*Zc], (block_length-2*Zc)*sizeof(unsigned char)); //systematic bits
+  memcpy(&channel_input[block_length-2*Zc], &d[0], ((nrows-no_punctured_columns) * Zc-removed_bit)*sizeof(unsigned char)); //systematic bits 2Zc + 2*block_length 
   //memcpy(channel_input,c,Kb*Zc*sizeof(unsigned char));
   return 0;
 }