srsRAN_4G/srslte/lib/mimo/layermap.c

/**
 *
 * \section COPYRIGHT
 *
 * Copyright 2013-2015 Software Radio Systems Limited
 *
 * \section LICENSE
 *
 * This file is part of the srsLTE library.
 *
 * srsLTE is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * srsLTE is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * A copy of the GNU Affero General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */


#include <stdio.h>
#include <assert.h>
#include <string.h>

#include "srslte/common/phy_common.h"
#include "srslte/mimo/layermap.h"



int srslte_layermap_single(cf_t *d, cf_t *x, int nof_symbols) {
  memcpy(x, d, sizeof(cf_t) * nof_symbols);
  return nof_symbols;
}

int srslte_layermap_diversity(cf_t *d, cf_t *x[SRSLTE_MAX_LAYERS], int nof_layers, int nof_symbols) {
  int i, j;
  for (i=0;i<nof_symbols/nof_layers;i++) {
    for (j=0;j<nof_layers;j++) {
      x[j][i] = d[nof_layers*i+j];
    }
  }
  return i;
}

int srslte_layermap_multiplex(cf_t *d[SRSLTE_MAX_CODEWORDS], cf_t *x[SRSLTE_MAX_LAYERS], int nof_cw, int nof_layers,
    int nof_symbols[SRSLTE_MAX_CODEWORDS]) {
  if (nof_cw == 1) {
    return srslte_layermap_diversity(d[0], x, nof_layers, nof_symbols[0]);
  } else {
    int n[2];
    n[0] = nof_layers / nof_cw;
    n[1] = nof_layers - n[0];
    if (nof_symbols[0] / n[0] == nof_symbols[1] / n[1]) {

      srslte_layermap_diversity(d[0], x,     n[0], nof_symbols[0]);
      srslte_layermap_diversity(d[1], &x[n[0]], n[1], nof_symbols[1]);
      return nof_symbols[0] / n[0];

    } else {
      fprintf(stderr, "Number of symbols in codewords 0 and 1 is not consistent (%d, %d)\n",
          nof_symbols[0], nof_symbols[1]);
      return -1;
    }
  }
  return 0;
}

/* Layer mapping generates the vector of layer-mapped symbols "x" based on the vector of data symbols "d"
 * Based on 36.211 6.3.3
 * Returns the number of symbols per layer (M_symb^layer in the specs)
 */
int srslte_layermap_type(cf_t *d[SRSLTE_MAX_CODEWORDS], cf_t *x[SRSLTE_MAX_LAYERS], int nof_cw, int nof_layers,
    int nof_symbols[SRSLTE_MAX_CODEWORDS], srslte_mimo_type_t type) {

  if (nof_cw > SRSLTE_MAX_CODEWORDS) {
    fprintf(stderr, "Maximum number of codewords is %d (nof_cw=%d)\n", SRSLTE_MAX_CODEWORDS, nof_cw);
    return -1;
  }
  if (nof_layers > SRSLTE_MAX_LAYERS) {
    fprintf(stderr, "Maximum number of layers is %d (nof_layers=%d)\n", SRSLTE_MAX_LAYERS, nof_layers);
    return -1;
  }
  if (nof_layers < nof_cw) {
    fprintf(stderr, "Number of codewords must be lower or equal than number of layers\n");
    return -1;
  }

  switch(type) {
  case SRSLTE_MIMO_TYPE_SINGLE_ANTENNA:
    if (nof_cw == 1 && nof_layers == 1) {
      return srslte_layermap_single(x[0], d[0], nof_symbols[0]);
    } else {
      fprintf(stderr, "Number of codewords and layers must be 1 for transmission on single antenna ports\n");
      return -1;
    }
    break;
  case SRSLTE_MIMO_TYPE_TX_DIVERSITY:
    if (nof_cw == 1) {
      if (nof_layers == 2 || nof_layers == 4) {
        return srslte_layermap_diversity(d[0], x, nof_layers, nof_symbols[0]);
      } else {
        fprintf(stderr, "Number of layers must be 2 or 4 for transmit diversity\n");
        return -1;
      }
    } else {
      fprintf(stderr, "Number of codewords must be 1 for transmit diversity\n");
      return -1;
    }
    break;
  case SRSLTE_MIMO_TYPE_SPATIAL_MULTIPLEX:
    return srslte_layermap_multiplex(d, x, nof_cw, nof_layers, nof_symbols);
    break;
  }
  return 0;
}









int srslte_layerdemap_single(cf_t *x, cf_t *d, int nof_symbols) {
  memcpy(d, x, sizeof(cf_t) * nof_symbols);
  return nof_symbols;
}
int srslte_layerdemap_diversity(cf_t *x[SRSLTE_MAX_LAYERS], cf_t *d, int nof_layers, int nof_layer_symbols) {
  int i, j;
  for (i=0;i<nof_layer_symbols;i++) {
    for (j=0;j<nof_layers;j++) {
      d[nof_layers*i+j] = x[j][i];
    }
  }
  return nof_layer_symbols * nof_layers;
}

int srslte_layerdemap_multiplex(cf_t *x[SRSLTE_MAX_LAYERS], cf_t *d[SRSLTE_MAX_CODEWORDS], int nof_layers, int nof_cw,
    int nof_layer_symbols, int nof_symbols[SRSLTE_MAX_CODEWORDS]) {
  if (nof_cw == 1) {
    return srslte_layerdemap_diversity(x, d[0], nof_layers, nof_layer_symbols);
  } else {
    int n[2];
    n[0] = nof_layers / nof_cw;
    n[1] = nof_layers - n[0];
    nof_symbols[0] = n[0] * nof_layer_symbols;
    nof_symbols[1] = n[1] * nof_layer_symbols;

    nof_symbols[0] = srslte_layerdemap_diversity(x,      d[0], n[0], nof_layer_symbols);
    nof_symbols[1] = srslte_layerdemap_diversity(&x[n[0]], d[1], n[1], nof_layer_symbols);
  }
  return 0;
}

/* Generates the vector of data symbols "d" based on the vector of layer-mapped symbols "x"
 * Based on 36.211 6.3.3
 * Returns 0 on ok and saves the number of symbols per codeword (M_symb^(q) in the specs) in
 * nof_symbols. Returns -1 on error
 */
int srslte_layerdemap_type(cf_t *x[SRSLTE_MAX_LAYERS], cf_t *d[SRSLTE_MAX_CODEWORDS], int nof_layers, int nof_cw,
    int nof_layer_symbols, int nof_symbols[SRSLTE_MAX_CODEWORDS], srslte_mimo_type_t type) {

  if (nof_cw > SRSLTE_MAX_CODEWORDS) {
    fprintf(stderr, "Maximum number of codewords is %d (nof_cw=%d)\n", SRSLTE_MAX_CODEWORDS, nof_cw);
    return -1;
  }
  if (nof_layers > SRSLTE_MAX_LAYERS) {
    fprintf(stderr, "Maximum number of layers is %d (nof_layers=%d)\n", SRSLTE_MAX_LAYERS, nof_layers);
    return -1;
  }
  if (nof_layers < nof_cw) {
    fprintf(stderr, "Number of codewords must be lower or equal than number of layers\n");
    return -1;
  }

  switch(type) {
  case SRSLTE_MIMO_TYPE_SINGLE_ANTENNA:
    if (nof_cw == 1 && nof_layers == 1) {
      nof_symbols[0] = srslte_layerdemap_single(x[0], d[0], nof_layer_symbols);
      nof_symbols[1] = 0;
    } else {
      fprintf(stderr, "Number of codewords and layers must be 1 for transmission on single antenna ports\n");
      return -1;
    }
    break;
  case SRSLTE_MIMO_TYPE_TX_DIVERSITY:
    if (nof_cw == 1) {
      if (nof_layers == 2 || nof_layers == 4) {
        nof_symbols[0] = srslte_layerdemap_diversity(x, d[0], nof_layers, nof_layer_symbols);
        nof_symbols[1] = 0;
      } else {
        fprintf(stderr, "Number of layers must be 2 or 4 for transmit diversity\n");
        return -1;
      }
    } else {
      fprintf(stderr, "Number of codewords must be 1 for transmit diversity\n");
      return -1;
    }
    break;
  case SRSLTE_MIMO_TYPE_SPATIAL_MULTIPLEX:
    return srslte_layerdemap_multiplex(x, d, nof_layers, nof_cw, nof_layer_symbols, nof_symbols);
    break;
  }
  return 0;
}