sequence.cpp

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#include <itpp/comm/sequence.h>
#include <itpp/base/converters.h>
#include <itpp/base/math/log_exp.h>


namespace itpp
{

LFSR::LFSR(const bvec &connections)
{
  set_connections(connections);
}

LFSR::LFSR(const ivec &connections)
{
  set_connections(connections);
}

void LFSR::set_connections(const bvec &connections)
{
  int N = connections.size() - 1;
  memory.set_size(N, true); // Should this be true???
  Connections = connections.right(N);
}

void LFSR::set_connections(const ivec &connections)
{
  bvec temp = oct2bin(connections);
  int N = temp.size() - 1;
  memory.set_size(N, true); // Should this be true???
  Connections = temp.right(N);
}

void LFSR::set_state(const bvec &state)
{
  it_assert(state.length() == memory.size(), "LFSR::set_state(): dimension mismatch");
  memory = state;
}

void LFSR::set_state(const ivec &state)
{
  bvec temp = oct2bin(state, 1);
  it_assert(temp.length() >= memory.size(), "LFSR::set_state(): dimension mismatch");
  memory = temp.right(memory.size());
}

bvec LFSR::shift(int no_shifts)
{
  it_assert(no_shifts > 0, "LFSR::shift(): shift must be positive");
  bvec temp(no_shifts);
  for (int i = 0;i < no_shifts;i++) {
    temp(i) = shift();
  }
  return temp;
}

//--------------------------- class Gold -------------------------
Gold::Gold(int degree)
{
  bvec mseq1_connections, mseq2_connections;
  switch (degree) {
  case 5:
    mseq1_connections = bvec("1 0 1 0 0 1");
    mseq2_connections = bvec("1 0 1 1 1 1");
    break;
  case 7:
    mseq1_connections = bvec("1 0 0 1 0 0 0 1");
    mseq2_connections = bvec("1 1 1 1 0 0 0 1");
    break;
  case 8:
    mseq1_connections = bvec("1 1 1 0 0 1 1 1 1");
    mseq2_connections = bvec("1 1 0 0 0 0 1 1 1");
    break;
  case 9:
    mseq1_connections = bvec("1 0 0 0 1 0 0 0 0 1");
    mseq2_connections = bvec("1 0 0 1 1 0 1 0 0 1");
    break;
  default:
    it_error("This degree of Gold sequence is not available");
  }
  mseq1.set_connections(mseq1_connections);
  mseq2.set_connections(mseq2_connections);
  N = pow2i(mseq1.get_length()) - 1;
}

Gold::Gold(const bvec &mseq1_connections, const bvec &mseq2_connections)
{
  it_assert(mseq1_connections.size() == mseq2_connections.size(), "Gold::Gold(): dimension mismatch");
  mseq1.set_connections(mseq1_connections);
  mseq2.set_connections(mseq2_connections);
  N = pow2i(mseq1.get_length()) - 1;
}

Gold::Gold(const ivec &mseq1_connections, const ivec &mseq2_connections)
{
  mseq1.set_connections(mseq1_connections);
  mseq2.set_connections(mseq2_connections);
  it_assert(mseq1.get_length() == mseq1.get_length(), "Gold::Gold(): dimension mismatch");
  N = pow2i(mseq1.get_length()) - 1;
}

void Gold::set_state(const bvec &state1, const bvec &state2)
{
  mseq1.set_state(state1);
  mseq2.set_state(state2);
}

void Gold::set_state(const ivec &state1, const ivec &state2)
{
  mseq1.set_state(state1);
  mseq2.set_state(state2);
}

bvec Gold::shift(int no_shifts)
{
  it_assert(no_shifts > 0, "Gold::shift(): shift must be positive");
  bvec temp(no_shifts);
  for (int i = 0;i < no_shifts;i++) {
    temp(i) = shift();
  }
  return temp;
}

bmat Gold::get_family(void)
{
  bmat codes(N + 2, N);
  bvec temp = dec2bin(mseq1.get_length(), 1);
  set_state(temp, temp);

  // The two m-seq.
  codes.set_row(0, mseq1.shift(N));
  codes.set_row(1, mseq2.shift(N));
  // The sum of mseq1 and all time shifts of mseq2
  for (int i = 0;i < N;i++) {
    codes.set_row(i + 2, codes.get_row(0) + concat((codes.get_row(1)).right(i), (codes.get_row(1)).left(N - i)));
  }
  return codes;
}

smat wcdma_spreading_codes(int SF)
{
  it_assert((SF == 1) || (SF == 2) || (SF == 4) || (SF == 8) || (SF == 16) || (SF == 32) || (SF == 64) || (SF == 128) || (SF == 256) || (SF == 512),
            "wcdma_spreading_codes: SF must equal 1, 2, 4, 8, 16, 32, 64, 128, 256, or 512");
  smat codes(SF, SF);
  if (SF == 1) {
    codes(0, 0) = short(1);
  }
  else {
    int i;
    smat prev_codes(SF / 2, SF / 2);
    prev_codes = wcdma_spreading_codes(SF / 2);
    for (i = 0; i < SF / 2; i++) {
      codes.set_row(2*i, concat(prev_codes.get_row(i), prev_codes.get_row(i)));
      codes.set_row(2*i + 1, concat(prev_codes.get_row(i), (-prev_codes.get_row(i))));
    }
  }
  return codes;
}

} // namespace itpp