Beispiel #1
0
/* Computes channel estimates for each reference in a slot and port.
 * Saves the nof_prb * 12 * nof_symbols channel estimates in the array ce
 */
void chest_ce_slot_port(chest_t *q, cf_t *input, cf_t *ce, int nslot, int port_id) {
	int i, j;
	cf_t x[2], y[MAX_NSYMB];

	assert(nslot >= 0 && nslot < NSLOTS_X_FRAME);
	assert(port_id >= 0 && port_id < q->nof_ports);
	assert(q->refsignal[port_id][nslot].nsymbols <= 2);

	refsignal_t *r = &q->refsignal[port_id][nslot];

	INFO("Estimating channel using %d reference signals\n", r->nof_refs);

	for (i=0;i<r->nof_refs;i++) {
		chest_ce_ref(q, input, nslot, port_id, i);
	}

	/* interpolate the symbols with references
	 * in the freq domain */
	for (i=0;i<r->nsymbols;i++) {
		interp_linear_offset(&r->ch_est[i * r->nof_refs/2],
				&ce[r->symbols_ref[i] * q->nof_prb * RE_X_RB], RE_X_RB/2,
				r->nof_refs/2, r->voffset, RE_X_RB/2-r->voffset);

	}
	/* now interpolate in the time domain */
	for (i=0;i<q->nof_prb * RE_X_RB; i++) {
		for (j=0;j<r->nsymbols;j++) {
			x[j] = ce[r->symbols_ref[j] * q->nof_prb * RE_X_RB + i];
		}
		interp_linear_offset(x, y, r->symbols_ref[1]-r->symbols_ref[0],
				2, r->symbols_ref[0], 3);
		for (j=0;j<q->nof_symbols;j++) {
			ce[j * q->nof_prb * RE_X_RB + i] = y[j];
		}
	}
}
Beispiel #2
0
/* Computes channel estimates for each reference in a slot and port.
 * Saves the nof_prb * 12 * nof_symbols channel estimates in the array ce
 */
int chest_ce_slot_port(chest_t *q, cf_t *input, cf_t *ce, uint32_t nslot, uint32_t port_id) {
  uint32_t i, j;
  cf_t x[2], y[MAX_NSYMB];

  int ret = LIBLTE_ERROR_INVALID_INPUTS;
  
  if (q         != NULL            &&
      input     != NULL            &&
      nslot     <  NSLOTS_X_FRAME  &&
      port_id   <  q->nof_ports) 
  {
    if (q->refsignal[port_id][nslot].nsymbols <= 2) {
      refsignal_t *r = &q->refsignal[port_id][nslot];

      DEBUG("Estimating channel slot=%d port=%d using %d reference signals\n",
          nslot, port_id, r->nof_refs);

      for (i=0;i<r->nof_refs;i++) {
        chest_ce_ref(q, input, nslot, port_id, i);
      }

      /* interpolate the symbols with references
      * in the freq domain */
      for (i=0;i<r->nsymbols;i++) {
#ifdef VOLK_INTERP
        interp_run_offset(&q->interp_freq[port_id], 
                          &r->ch_est[i * r->nof_refs/2], &ce[r->symbols_ref[i] * q->nof_re], 
                          r->voffset, RE_X_RB/2-r->voffset);
#else
        interp_linear_offset(&r->ch_est[i * r->nof_refs/2],
            &ce[r->symbols_ref[i] * q->nof_re], RE_X_RB/2,
            r->nof_refs/2, r->voffset, RE_X_RB/2-r->voffset);
#endif
      }
      /* now interpolate in the time domain */
      for (i=0;i<q->nof_re; i++) {
        if (r->nsymbols > 1) {
          for (j=0;j<r->nsymbols;j++) {
            x[j] = ce[r->symbols_ref[j] * q->nof_re + i];
          }
#ifdef VOLK_INTERP
          interp_run_offset(&q->interp_time[port_id], x, y, 
                            r->symbols_ref[0], 3);
#else
          interp_linear_offset(x, y, r->symbols_ref[1]-r->symbols_ref[0],
              2, r->symbols_ref[0], 3);
#endif
        } else {
          for (j=0;j<MAX_NSYMB;j++) {
            y[j] = ce[r->symbols_ref[0] * q->nof_re + i];
          }
        }       
        for (j=0;j<q->nof_symbols;j++) {
          ce[j * q->nof_re + i] = y[j];
        }
      }
      ret = LIBLTE_SUCCESS;
    }
  }
  return ret;
}
Beispiel #3
0
/* Performs 1st order linear interpolation */
void interp_linear(cf_t *input, cf_t *output, int M, int len) {
	interp_linear_offset(input, output, M, len, 0, 0);
}