modulating prs

openair1/PHY/NR_TRANSPORT/nr_prs.c

-//int nr_generate_prs(){}
+/*
+ * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The OpenAirInterface Software Alliance licenses this file to You under
+ * the OAI Public License, Version 1.1  (the "License"); you may not use this file
+ * except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.openairinterface.org/?page_id=698
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *-------------------------------------------------------------------------------
+ * For more information about the OpenAirInterface (OAI) Software Alliance:
+ *      contact@openairinterface.org
+ */
+
+/*! \file PHY/NR_TRANSPORT/nr_pbch.c
+* \brief Top-level routines for generating the PBCH/BCH physical/transport channel V15.1 03/2018
+* \author Guy De Souza
+* \thanks Special Thanks to Son Dang for helpful contributions and testing
+* \date 2018
+* \version 0.1
+* \company Eurecom
+* \email: desouza@eurecom.fr
+* \note
+* \warning
+*/
+
+#include "PHY/defs_gNB.h"
+#include "PHY/NR_TRANSPORT/nr_transport_proto.h"
+#include "PHY/LTE_REFSIG/lte_refsig.h"
+#include "PHY/sse_intrin.h"
+
+//#define DEBUG_PBCH
+//#define DEBUG_PBCH_ENCODING
+//#define DEBUG_PBCH_DMRS
+
+extern short nr_qpsk_mod_table[8];
+
+const uint8_t nr_pbch_payload_interleaving_pattern[32] = {16, 23, 18, 17, 8, 30, 10, 6, 24, 7, 0, 5, 3, 2, 1, 4,
+                                                    9, 11, 12, 13, 14, 15, 19, 20, 21, 22, 25, 26, 27, 28, 29, 31
+                                                   };
 
 int nr_generate_pbch_dmrs(uint32_t *gold_pbch_dmrs,
                           int32_t *txdataF,
@@ -94,3 +140,295 @@ int nr_generate_pbch_dmrs(uint32_t *gold_pbch_dmrs,
 #endif
   return 0;
 }
+
+static void nr_pbch_scrambling(NR_gNB_PBCH *pbch,
+                        uint32_t Nid,
+                        uint8_t nushift,
+                        uint16_t M,
+                        uint16_t length,
+                        uint8_t encoded,
+                        uint32_t unscrambling_mask) {
+  uint8_t reset, offset;
+  uint32_t x1, x2, s=0;
+  uint32_t *pbch_e = pbch->pbch_e;
+  reset = 1;
+  // x1 is set in lte_gold_generic
+  x2 = Nid;
+
+  // The Gold sequence is shifted by nushift* M, so we skip (nushift*M /32) double words
+  for (int i=0; i<(uint16_t)ceil(((float)nushift*M)/32); i++) {
+    s = lte_gold_generic(&x1, &x2, reset);
+    reset = 0;
+  }
+
+  // Scrambling is now done with offset (nushift*M)%32
+  offset = (nushift*M)&0x1f;
+#ifdef DEBUG_PBCH_ENCODING
+  printf("Scrambling params: nushift %d M %d length %d encoded %d offset %d\n", nushift, M, length, encoded, offset);
+#endif
+#ifdef DEBUG_PBCH_ENCODING
+  printf("s: %04x\t", s);
+#endif
+  int k = 0;
+
+  if (!encoded) {
+    /// 1st Scrambling
+    for (int i = 0; i < length; ++i) {
+      if ((unscrambling_mask>>i)&1)
+        pbch->pbch_a_prime ^= ((pbch->pbch_a_interleaved>>i)&1)<<i;
+      else {
+        if (((k+offset)&0x1f)==0) {
+          s = lte_gold_generic(&x1, &x2, reset);
+          reset = 0;
+        }
+
+        pbch->pbch_a_prime ^= (((pbch->pbch_a_interleaved>>i)&1) ^ ((s>>((k+offset)&0x1f))&1))<<i;
+        k++;                  /// k increase only when payload bit is not special bit
+      }
+    }
+  } else {
+    /// 2nd Scrambling
+    for (int i = 0; i < length; ++i) {
+      if (((i+offset)&0x1f)==0) {
+        s = lte_gold_generic(&x1, &x2, reset);
+        reset = 0;
+      }
+
+      pbch_e[i>>5] ^= (((s>>((i+offset)&0x1f))&1)<<(i&0x1f));
+    }
+  }
+}
+
+
+void nr_init_pbch_interleaver(uint8_t *interleaver) {
+  uint8_t j_sfn=0, j_hrf=10, j_ssb=11, j_other=14;
+  memset((void *)interleaver,0, NR_POLAR_PBCH_PAYLOAD_BITS);
+
+  for (uint8_t i=0; i<NR_POLAR_PBCH_PAYLOAD_BITS; i++)
+    if (!i) // choice bit:1
+      *(interleaver+i) = *(nr_pbch_payload_interleaving_pattern+j_other++);
+    else if (i<7) //Sfn bits:6
+      *(interleaver+i) = *(nr_pbch_payload_interleaving_pattern+j_sfn++);
+    else if (i<24) // other:17
+      *(interleaver+i) = *(nr_pbch_payload_interleaving_pattern+j_other++);
+    else if (i<28) // Sfn:4
+      *(interleaver+i) = *(nr_pbch_payload_interleaving_pattern+j_sfn++);
+    else if (i==28) // Hrf bit:1
+      *(interleaver+i) = *(nr_pbch_payload_interleaving_pattern+j_hrf);
+    else // Ssb bits:3
+      *(interleaver+i) = *(nr_pbch_payload_interleaving_pattern+j_ssb++);
+}
+
+int nr_generate_pbch(NR_gNB_PBCH *pbch,
+		     nfapi_nr_dl_tti_ssb_pdu *ssb_pdu,
+                     uint8_t *interleaver,
+                     int32_t *txdataF,
+                     int16_t amp,
+                     uint8_t ssb_start_symbol,
+                     uint8_t n_hf,
+                     int sfn,
+                     nfapi_nr_config_request_scf_t *config,
+                     NR_DL_FRAME_PARMS *frame_parms) {
+  int k,l,m;
+  //int16_t a;
+  int16_t mod_pbch_e[NR_POLAR_PBCH_E];
+  uint8_t idx=0;
+  uint16_t M;
+  uint8_t nushift;
+  uint32_t unscrambling_mask;
+  uint64_t a_reversed=0;
+  LOG_D(PHY, "PBCH generation started\n");
+  ///Payload generation
+  memset((void *)pbch, 0, sizeof(NR_gNB_PBCH));
+  pbch->pbch_a=0;
+  uint8_t ssb_index = ssb_pdu->ssb_pdu_rel15.SsbBlockIndex;
+  uint8_t *pbch_pdu = (uint8_t*)&ssb_pdu->ssb_pdu_rel15.bchPayload;
+  uint8_t Lmax = frame_parms->Lmax;
+  for (int i=0; i<NR_PBCH_PDU_BITS; i++)
+    pbch->pbch_a |= ((pbch_pdu[i>>3]>>(7-(i&7)))&1)<<i;
+
+  #ifdef DEBUG_PBCH_ENCODING
+  for (int i=0; i<3; i++)
+    printf("pbch_pdu[%d]: 0x%02x\n", i, pbch_pdu[i]);
+
+  printf("PBCH payload = 0x%08x\n",pbch->pbch_a);
+  #endif
+
+  // Extra byte generation
+  for (int i=0; i<4; i++)
+    pbch->pbch_a |= ((sfn>>(3-i))&1)<<(24+i); // resp. 4th, 3rd, 2nd ans 1st lsb of sfn
+
+  pbch->pbch_a |= n_hf<<28; // half frame index bit
+
+  if (Lmax == 64)
+    for (int i=0; i<3; i++)
+      pbch->pbch_a |= ((ssb_index>>(5-i))&1)<<(29+i); // resp. 6th, 5th and 4th bits of ssb_index
+  else
+    pbch->pbch_a |= ((config->ssb_table.ssb_subcarrier_offset.value>>4)&1)<<29; //MSB of k_SSB (bit index 4)
+
+  LOG_D(PHY,"After extra byte: pbch_a = 0x%08x\n",pbch->pbch_a);
+
+  // Payload interleaving
+
+  for (int i=0; i<NR_POLAR_PBCH_PAYLOAD_BITS; i++) {
+    pbch->pbch_a_interleaved |= ((pbch->pbch_a>>i)&1)<<(*(interleaver+i));
+#ifdef DEBUG_PBCH_ENCODING
+    printf("i %d out 0x%08x ilv %d (in>>i)&1) %d\n", i, pbch->pbch_a_interleaved, *(interleaver+i), (pbch->pbch_a>>i)&1);
+#endif
+  }
+
+#ifdef DEBUG_PBCH_ENCODING
+  printf("Interleaving:\n");
+  printf("pbch_a_interleaved: 0x%08x\n", pbch->pbch_a_interleaved);
+#endif
+  // Scrambling
+  unscrambling_mask = (Lmax ==64)? 0x100006D:0x1000041;
+  M = (Lmax == 64)? (NR_POLAR_PBCH_PAYLOAD_BITS - 6) : (NR_POLAR_PBCH_PAYLOAD_BITS - 3);
+  nushift = (((sfn>>2)&1)<<1) ^ ((sfn>>1)&1);
+  pbch->pbch_a_prime = 0;
+  nr_pbch_scrambling(pbch, (uint32_t)config->cell_config.phy_cell_id.value, nushift, M, NR_POLAR_PBCH_PAYLOAD_BITS, 0, unscrambling_mask);
+#ifdef DEBUG_PBCH_ENCODING
+  printf("Payload scrambling: nushift %d M %d sfn3 %d sfn2 %d\n", nushift, M, (sfn>>2)&1, (sfn>>1)&1);
+  printf("pbch_a_prime: 0x%08x\n", pbch->pbch_a_prime);
+#endif
+
+  // Encoder reversal
+  for (int i=0; i<NR_POLAR_PBCH_PAYLOAD_BITS; i++)
+    a_reversed |= (((uint64_t)pbch->pbch_a_prime>>i)&1)<<(31-i);
+
+  /// CRC, coding and rate matching
+  polar_encoder_fast (&a_reversed, (void*)pbch->pbch_e, 0, 0,
+                      nr_polar_params( NR_POLAR_PBCH_MESSAGE_TYPE, NR_POLAR_PBCH_PAYLOAD_BITS, NR_POLAR_PBCH_AGGREGATION_LEVEL,0,NULL)
+                     );
+#ifdef DEBUG_PBCH_ENCODING
+  printf("Channel coding:\n");
+
+  for (int i=0; i<NR_POLAR_PBCH_E_DWORD; i++)
+    printf("pbch_e[%d]: 0x%08x\t", i, pbch->pbch_e[i]);
+
+  printf("\n");
+#endif
+  /// Scrambling
+  M =  NR_POLAR_PBCH_E;
+  nushift = (Lmax==4)? ssb_index&3 : ssb_index&7;
+  nr_pbch_scrambling(pbch, (uint32_t)config->cell_config.phy_cell_id.value, nushift, M, NR_POLAR_PBCH_E, 1, 0);
+#ifdef DEBUG_PBCH_ENCODING
+  printf("Scrambling:\n");
+
+  for (int i=0; i<NR_POLAR_PBCH_E_DWORD; i++)
+    printf("pbch_e[%d]: 0x%08x\t", i, pbch->pbch_e[i]);
+
+  printf("\n");
+#endif
+
+  /// QPSK modulation
+  for (int i=0; i<NR_POLAR_PBCH_E>>1; i++) {
+    idx = ((pbch->pbch_e[(i<<1)>>5]>>((i<<1)&0x1f))&3);
+    mod_pbch_e[i<<1] = nr_qpsk_mod_table[idx<<1];
+    mod_pbch_e[(i<<1)+1] = nr_qpsk_mod_table[(idx<<1)+1];
+#ifdef DEBUG_PBCH
+    printf("i %d idx %d  mod_pbch %d %d\n", i, idx, mod_pbch_e[2*i], mod_pbch_e[2*i+1]);
+#endif
+  }
+
+  /// Resource mapping
+  nushift = config->cell_config.phy_cell_id.value &3;
+  // PBCH modulated symbols are mapped  within the SSB block on symbols 1, 2, 3 excluding the subcarriers used for the PBCH DMRS
+  ///symbol 1  [0:239] -- 180 mod symbols
+  k = frame_parms->first_carrier_offset + frame_parms->ssb_start_subcarrier;
+  l = ssb_start_symbol + 1;
+  m = 0;
+
+  for (int ssb_sc_idx = 0; ssb_sc_idx < 240; ssb_sc_idx++) {
+    if ((ssb_sc_idx&3) == nushift) {  //skip DMRS
+      k++;
+      continue;
+    } else {
+#ifdef DEBUG_PBCH
+      printf("m %d ssb_sc_idx %d at k %d of l %d\n", m, ssb_sc_idx, k, l);
+#endif
+      ((int16_t *)txdataF)[(l*frame_parms->ofdm_symbol_size + k)<<1]       = (amp * mod_pbch_e[m<<1]) >> 15;
+      ((int16_t *)txdataF)[((l*frame_parms->ofdm_symbol_size + k)<<1) + 1] = (amp * mod_pbch_e[(m<<1) + 1]) >> 15;
+      k++;
+      m++;
+    }
+
+    if (k >= frame_parms->ofdm_symbol_size)
+      k-=frame_parms->ofdm_symbol_size;
+  }
+
+  ///symbol 2  [0:47 ; 192:239] -- 72 mod symbols
+  k = frame_parms->first_carrier_offset + frame_parms->ssb_start_subcarrier;
+  l++;
+  m=180;
+
+  for (int ssb_sc_idx = 0; ssb_sc_idx < 48; ssb_sc_idx++) {
+    if ((ssb_sc_idx&3) == nushift) {
+      k++;
+      continue;
+    } else {
+#ifdef DEBUG_PBCH
+      printf("m %d ssb_sc_idx %d at k %d of l %d\n", m, ssb_sc_idx, k, l);
+#endif
+      ((int16_t *)txdataF)[(l*frame_parms->ofdm_symbol_size + k)<<1]       = (amp * mod_pbch_e[m<<1]) >> 15;
+      ((int16_t *)txdataF)[((l*frame_parms->ofdm_symbol_size + k)<<1) + 1] = (amp * mod_pbch_e[(m<<1) + 1]) >> 15;
+      k++;
+      m++;
+    }
+
+    if (k >= frame_parms->ofdm_symbol_size)
+      k-=frame_parms->ofdm_symbol_size;
+  }
+
+  k += 144;
+
+  if (k >= frame_parms->ofdm_symbol_size)
+    k-=frame_parms->ofdm_symbol_size;
+
+  m=216;
+
+  for (int ssb_sc_idx = 192; ssb_sc_idx < 240; ssb_sc_idx++) {
+    if ((ssb_sc_idx&3) == nushift) {
+      k++;
+      continue;
+    } else {
+#ifdef DEBUG_PBCH
+      printf("m %d ssb_sc_idx %d at k %d of l %d\n", m, ssb_sc_idx, k, l);
+#endif
+      ((int16_t *)txdataF)[(l*frame_parms->ofdm_symbol_size + k)<<1]       = (amp * mod_pbch_e[m<<1]) >> 15;
+      ((int16_t *)txdataF)[((l*frame_parms->ofdm_symbol_size + k)<<1) + 1] = (amp * mod_pbch_e[(m<<1) + 1]) >> 15;
+      k++;
+      m++;
+    }
+
+    if (k >= frame_parms->ofdm_symbol_size)
+      k-=frame_parms->ofdm_symbol_size;
+  }
+
+  ///symbol 3  [0:239] -- 180 mod symbols
+  k = frame_parms->first_carrier_offset + frame_parms->ssb_start_subcarrier;
+  l++;
+  m=252;
+
+  for (int ssb_sc_idx = 0; ssb_sc_idx < 240; ssb_sc_idx++) {
+    if ((ssb_sc_idx&3) == nushift) {
+      k++;
+      continue;
+    } else {
+#ifdef DEBUG_PBCH
+      printf("m %d ssb_sc_idx %d at k %d of l %d\n", m, ssb_sc_idx, k, l);
+#endif
+      ((int16_t *)txdataF)[(l*frame_parms->ofdm_symbol_size + k)<<1]       = (amp * mod_pbch_e[m<<1]) >> 15;
+      ((int16_t *)txdataF)[((l*frame_parms->ofdm_symbol_size + k)<<1) + 1] = (amp * mod_pbch_e[(m<<1) + 1]) >> 15;
+      k++;
+      m++;
+    }
+
+
+    if (k >= frame_parms->ofdm_symbol_size)
+      k-=frame_parms->ofdm_symbol_size;
+  }
+
+
+  return 0;
+}