group_hopping.c

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/*! \file PHY/LTE_TRANSPORT/group_hopping.c
* \brief Top-level routines for group/sequence hopping and nPRS sequence generationg for DRS and PUCCH from 36-211, V8.6 2009-03
* \author R. Knopp
* \date 2011
* \version 0.1
* \company Eurecom
* \email: knopp@eurecom.fr
* \note
* \warning
*/
#include "PHY/defs.h"

//#define DEBUG_GROUPHOP 1

void generate_grouphop(LTE_DL_FRAME_PARMS *frame_parms)
{

  uint8_t ns;
  uint8_t reset=1;
  uint32_t x1, x2, s=0;
  // This is from Section 5.5.1.3
  uint32_t fss_pusch = frame_parms->Nid_cell + frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.groupAssignmentPUSCH;

  x2 = frame_parms->Nid_cell/30;
#ifdef DEBUG_GROUPHOP
  printf("[PHY] GroupHop:");
#endif

  for (ns=0; ns<20; ns++) {
    if (frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.groupHoppingEnabled == 0)
      frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.grouphop[ns] = fss_pusch%30;
    else {
      if ((ns&3) == 0) {
        s = lte_gold_generic(&x1,&x2,reset);
        reset = 0;
      }

      frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.grouphop[ns] = (((uint8_t*)&s)[ns&3]+fss_pusch)%30;
    }

#ifdef DEBUG_GROUPHOP
    printf("%d.",frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.grouphop[ns]);
#endif
  }

#ifdef DEBUG_GROUPHOP
  printf("\n");
#endif
}

void generate_seqhop(LTE_DL_FRAME_PARMS *frame_parms)
{

  uint8_t ns,reset=1;
  uint32_t x1, x2, s=0;
  // This is from Section 5.5.1.3
  uint32_t fss_pusch = frame_parms->Nid_cell + frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.groupAssignmentPUSCH;

  x2 = (32*(frame_parms->Nid_cell/30) + fss_pusch)%30;

  s = lte_gold_generic(&x1,&x2,reset);
#ifdef DEBUG_GROUPHOP
  printf("[PHY] SeqHop:");
#endif

  for (ns=0; ns<20; ns++) {
    if ((frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.groupHoppingEnabled == 0) &&
        (frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.sequenceHoppingEnabled == 1))
      frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.seqhop[ns] = (s>>(ns&0x1f))&1;
    else
      frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.seqhop[ns] = 0;

#ifdef DEBUG_GROUPHOP
    printf("%d.",frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.seqhop[ns]);
#endif
  }

#ifdef DEBUG_GROUPHOP
  printf("\n");
#endif
}

void generate_nPRS(LTE_DL_FRAME_PARMS *frame_parms)
{

  uint16_t n=0;
  uint8_t reset=1;
  uint32_t x1, x2, s=0;
  // This is from Section 5.5.1.3
  uint8_t Nsymb_UL = (frame_parms->Ncp_UL == NORMAL) ? 7 : 6;
  uint16_t next = 0;
  uint8_t ns=0;

  uint32_t fss_pusch = frame_parms->Nid_cell + frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.groupAssignmentPUSCH;

  x2 = (32*(uint32_t)(frame_parms->Nid_cell/30)) + fss_pusch;
#ifdef DEBUG_GROUPHOP
  printf("[PHY] nPRS:");
#endif

  for (n=0; n<(20*Nsymb_UL); n++) { //loop over total number of bytes to generate
    if ((n&3) == 0) {
      s = lte_gold_generic(&x1,&x2,reset);
      reset = 0;
      //      printf("n %d : s (%d,%d,%d,%d)\n",n,((uint8_t*)&s)[0],((uint8_t*)&s)[1],((uint8_t*)&s)[2],((uint8_t*)&s)[3]);
    }

    if (n == next) {
      frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.nPRS[ns] = ((uint8_t*)&s)[next&3];
#ifdef DEBUG_GROUPHOP
      printf("%d.",frame_parms->pusch_config_common.ul_ReferenceSignalsPUSCH.nPRS[ns]);
#endif
      ns++;
      next+=Nsymb_UL;
    }
  }

#ifdef DEBUG_GROUPHOP
  printf("\n");
#endif
}

void init_ul_hopping(LTE_DL_FRAME_PARMS *frame_parms)
{

  generate_grouphop(frame_parms);
  generate_seqhop(frame_parms);
  generate_nPRS(frame_parms);
}