CDMA (2)

Here is an improvement of the previous code. To simulate bit stream, I add a function to generate random number generator for each node.

#include <stdio.h>
#include <stdlib.h>

#define NUMBER_OF_SEQUENCES     8
#define IS_ORTHOGONAL           0
#define IS_NOT_ORTHOGONAL       -1
#define N_NODES                 4

typedef struct {
int chip[NUMBER_OF_SEQUENCES];
} ChipSeq;


void PrintChipSeq(ChipSeq *X);

int Add(ChipSeq *X, ChipSeq* Y, ChipSeq *R)
{
int i;
for (i=0; ichip[i] = X->chip[i] + Y->chip[i];
}
return 0;
}


int DotProduct(ChipSeq *X, ChipSeq *Y, ChipSeq *Res)
{
ChipSeq temp;
int i;

if (!X || !Y)
    return -1;

for(i=0; ichip[i] = X->chip[i] * Y->chip[i];
return 0;
}

void InitChip(ChipSeq *A, int initVal)
{
int i;

for(i=0; ichip[i] = initVal;
}


int CheckOrthogonality(ChipSeq *X, ChipSeq *Y)
{
int i;
int sum = 0;

for (i=0; ichip[i] * Y->chip[i];

if (sum/NUMBER_OF_SEQUENCES == 0)
    return IS_ORTHOGONAL;  // it is orthogonal
else
    return IS_NOT_ORTHOGONAL;
}


int RecoverBit(ChipSeq *S, ChipSeq *SenderSeq)
{
int i;
int sum=0;

for(i=0; ichip[i] * SenderSeq->chip[i];

return (sum/NUMBER_OF_SEQUENCES <= 0 ? 0 : 1); }   int Negative(ChipSeq *A, ChipSeq *Comp) {     int i;                          for(i=0; ichip[i] = -(A->chip[i]);
}


void PrintChipSeq(ChipSeq *X)
{
int i;

printf("[ ");
for (i=0; ichip[i]);
printf("]");
}

void CopySeq(ChipSeq* src, ChipSeq* dest)
{
if (src && dest)
    memcpy(dest, src, sizeof(ChipSeq));
}


void ConvertToBipolar(ChipSeq *A, ChipSeq *Bip)
{
int i;

for(i=0; ichip[i] == 1)
        Bip->chip[i] = 1;
    if (A->chip[i] == 0)
        Bip->chip[i] = -1;
}
}


void Send(int n, int bit[], ChipSeq node[], ChipSeq *S)
{
   ChipSeq bp[N_NODES], temp;
   int i,j;

   if (n>N_NODES) return;
   for(i=0; i      if (bit[i]==1)
          CopySeq(&node[i], &bp[i]);
      else
          Negative(&node[i], &bp[i]);
      }
      memset(S, 0, sizeof(ChipSeq));
      for(i=0; i          Add(S, &bp[i], S);
   }
}


int GenerateRandom(void)
{
 return random() % 2;
}


int main(int argc, char *argv[])
{
 int i,j;
 ChipSeq node[4] = { {{0, 0, 0, 1, 1, 0, 1, 1}},
         {{0, 0, 1, 0, 1, 1, 1, 0}},
      {{0, 1, 0, 1, 1, 1, 0, 0}},
      {{0, 1, 0, 0, 0, 0, 1, 0}}
     }; 
 ChipSeq temp, b[N_NODES], s;
 int bit[N_NODES];
 time_t t;

 for(i=0; i  printf("Node[%u] = ", i);
  PrintChipSeq(&node[i]);   
  printf("\n");
  ConvertToBipolar(&node[i], &b[i]);
  printf("Bipolar(node[%u]) = ", i);
  PrintChipSeq(&b[i]);
  printf("\n");
 }

 for (i=0; i  for(j=i+1; j   if (CheckOrthogonality(&b[i], &b[j])==IS_ORTHOGONAL)
    printf("Node[%u] & node[%u] is orthogonal\n", i, j);
   else {
    printf("Node[%u] & node[%u] is NOT orthogonal\n", i, j);
    exit(0);
   }
  }
 }

 time(&t);  
 srandom(t);
 for (i=0; i<100; i++) {
  bit[0] = GenerateRandom();
  bit[1] = GenerateRandom();
  bit[2] = GenerateRandom();
  bit[3] = GenerateRandom();
  printf("Send: A=%u B=%u C=%u D=%u\n", bit[0], bit[1], bit[2], bit[3]);
  Send(N_NODES, bit, b, &s);
  printf("S = !A + !B + !C + !D = ");
  PrintChipSeq(&s);
  printf("\n"); 
 
  printf("Recover bit from A: S*A\n");
  printf("Bit sent from A was: %d\n", RecoverBit(&s, &b[0]));
  printf("\n");

  printf("Recover bit from B: S*B\n");
  printf("Bit sent from B was: %d\n", RecoverBit(&s, &b[1]));
  printf("\n");

  printf("Recover bit from C: S*C\n");
  printf("Bit sent from C was: %d\n", RecoverBit(&s, &b[2]));
  printf("\n");

  printf("Recover bit from D: S*D\n");
  printf("Bit sent from D was: %d\n", RecoverBit(&s, &b[3]));
  printf("\n");
 }
}

CDMA

I developed this simulation just for fun and only in a few minutes:

#include
#include

#define NUMBER_OF_SEQUENCES 8
#define IS_ORTHOGONAL 0
#define IS_NOT_ORTHOGONAL -1



typedef struct {
int chip[NUMBER_OF_SEQUENCES];
} ChipSeq;


int Add(ChipSeq *X, ChipSeq* Y, ChipSeq *R)
{
int i;

for (i=0; ichip[i] = X->chip[i] + Y->chip[i];

return 0;
}


int DotProduct(ChipSeq *X, ChipSeq *Y, ChipSeq *Res)
{
ChipSeq temp;
int i;

if (!X || !Y)
return -1;

for(i=0; ichip[i] = X->chip[i] * Y->chip[i];
return 0;
}

void InitChip(ChipSeq *A, int initVal)
{
int i;

for(i=0; ichip[i] = initVal;
}


int CheckOrthogonality(ChipSeq *X, ChipSeq *Y)
{
int i;
int sum = 0;

for (i=0; ichip[i] * Y->chip[i];

if (sum/NUMBER_OF_SEQUENCES == 0)
return IS_ORTHOGONAL; // it is orthogonal
else
return IS_NOT_ORTHOGONAL;
}


int RecoverBit(ChipSeq *S, ChipSeq *SenderSeq)
{
int i;
int sum=0;

for(i=0; ichip[i] * SenderSeq->chip[i];

return sum/NUMBER_OF_SEQUENCES;
}


int Negative(ChipSeq *A, ChipSeq *Comp)
{
int i;
for(i=0; ichip[i] = -(A->chip[i]);
}


void PrintChipSeq(ChipSeq *X)
{
int i;

printf("[ ");
for (i=0; ichip[i]);
printf("]");
}

void CopySeq(ChipSeq* src, ChipSeq* dest)
{
memcpy(&dest, &src, sizeof(ChipSeq));
}


void ConvertToBipolar(ChipSeq *A, ChipSeq *Bip)
{
int i;

for(i=0; ichip[i] == 1)
Bip->chip[i] = 1;
if (A->chip[i] == 0)
Bip->chip[i] = -1;
}
}


int main(int argc, char *argv[])
{
ChipSeq A = { {0, 0, 0, 1, 1, 0, 1, 1}};
ChipSeq B = { {0, 0, 1, 0, 1, 1, 1, 0}};
ChipSeq C = { {0, 1, 0, 1, 1, 1, 0, 0}};
ChipSeq D = { {0, 1, 0, 0, 0, 0, 1, 0}};
ChipSeq temp, ba, bb, bc, bd, ca, cb, cc, cd, sum;

printf("A = ");
PrintChipSeq(&A);
printf("\n");
ConvertToBipolar(&A, &ba);
printf("Bipolar(A) = ");
PrintChipSeq(&ba);
printf("\n");

printf("B = ");
PrintChipSeq(&B);
printf("\n");
ConvertToBipolar(&B, &bb);

printf("C = ");
PrintChipSeq(&C);
printf("\n");
ConvertToBipolar(&C, &bc);

printf("D = ");
PrintChipSeq(&D);
printf("\n");
ConvertToBipolar(&C, &bd);

// A + B + C sends 0 bits
Negative(&ba, &ca);
printf("!A = "); PrintChipSeq(&ca); printf("\n");
Negative(&bb, &cb);
printf("!B = "); PrintChipSeq(&cb); printf("\n");
Negative(&bc, &cc);
printf("!C = "); PrintChipSeq(&cc); printf("\n");

// now add
Add(&ca, &cb, &temp);

Add(&temp, &cc, ∑);
printf("S = !A + !B + !C = ");
PrintChipSeq(∑);
printf("\n");

printf("Recover bit from A: S*A\n");
printf("Bit sent from A was: %d\n", RecoverBit(∑, &A));
printf("\n");

printf("Recover bit from B: S*B\n");
printf("Bit sent from B was: %d\n", RecoverBit(∑, &B));
printf("\n");

printf("Recover bit from C: S*C\n");
printf("Bit sent from C was: %d\n", RecoverBit(∑, &C));
printf("\n");

}

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