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openairinterface5g/openair1/PHY/NR_TRANSPORT/nr_pbch.c
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/*
* 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/sse_intrin.h"
#include "executables/softmodem-common.h"
#include "openair1/PHY/NR_REFSIG/nr_refsig_common.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,
c16_t *txdataF,
int16_t amp,
uint8_t ssb_start_symbol,
nfapi_nr_config_request_scf_t *config,
NR_DL_FRAME_PARMS *frame_parms) {
int k,l;
//int16_t a;
int16_t mod_dmrs[NR_PBCH_DMRS_LENGTH<<1];
uint8_t idx=0;
uint8_t nushift = config->cell_config.phy_cell_id.value &3;
LOG_D(PHY, "PBCH DMRS mapping started at symbol %d shift %d\n", ssb_start_symbol+1, nushift);
/// QPSK modulation
for (int m=0; m<NR_PBCH_DMRS_LENGTH; m++) {
idx = (((gold_pbch_dmrs[(m<<1)>>5])>>((m<<1)&0x1f))&3);
mod_dmrs[m<<1] = nr_qpsk_mod_table[idx<<1];
mod_dmrs[(m<<1)+1] = nr_qpsk_mod_table[(idx<<1) + 1];
#ifdef DEBUG_PBCH_DMRS
printf("m %d idx %d gold seq %u b0-b1 %d-%d mod_dmrs %d %d\n", m, idx, gold_pbch_dmrs[(m<<1)>>5], (((gold_pbch_dmrs[(m<<1)>>5])>>((m<<1)&0x1f))&1),
(((gold_pbch_dmrs[((m<<1)+1)>>5])>>(((m<<1)+1)&0x1f))&1), mod_dmrs[(m<<1)], mod_dmrs[(m<<1)+1]);
#endif
}
/// Resource mapping
// PBCH DMRS are mapped within the SSB block on every fourth subcarrier starting from nushift of symbols 1, 2, 3
///symbol 1 [0+nushift:4:236+nushift] -- 60 mod symbols
k = frame_parms->first_carrier_offset + frame_parms->ssb_start_subcarrier + nushift;
l = ssb_start_symbol + 1;
for (int m = 0; m < 60; m++) {
#ifdef DEBUG_PBCH_DMRS
printf("m %d at k %d of l %d\n", m, k, l);
#endif
((int16_t *)txdataF)[(l*frame_parms->ofdm_symbol_size + k)<<1] = (amp * mod_dmrs[m<<1]) >> 15;
((int16_t *)txdataF)[((l*frame_parms->ofdm_symbol_size + k)<<1) + 1] = (amp * mod_dmrs[(m<<1) + 1]) >> 15;
#ifdef DEBUG_PBCH_DMRS
printf("(%d,%d)\n",
((int16_t *)txdataF)[(l*frame_parms->ofdm_symbol_size + k)<<1],
((int16_t *)txdataF)[((l*frame_parms->ofdm_symbol_size + k)<<1)+1]);
#endif
k+=4;
if (k >= frame_parms->ofdm_symbol_size)
k-=frame_parms->ofdm_symbol_size;
}
///symbol 2 [0+u:4:44+nushift ; 192+nu:4:236+nushift] -- 24 mod symbols
k = frame_parms->first_carrier_offset + frame_parms->ssb_start_subcarrier + nushift;
l++;
for (int m = 60; m < 84; m++) {
#ifdef DEBUG_PBCH_DMRS
printf("m %d at k %d of l %d\n", m, k, l);
#endif
((int16_t *)txdataF)[(l*frame_parms->ofdm_symbol_size + k)<<1] = (amp * mod_dmrs[m<<1]) >> 15;
((int16_t *)txdataF)[((l*frame_parms->ofdm_symbol_size + k)<<1) + 1] = (amp * mod_dmrs[(m<<1) + 1]) >> 15;
#ifdef DEBUG_PBCH_DMRS
printf("(%d,%d)\n",
((int16_t *)txdataF)[(l*frame_parms->ofdm_symbol_size + k)<<1],
((int16_t *)txdataF)[((l*frame_parms->ofdm_symbol_size + k)<<1)+1]);
#endif
k+=(m==71)?148:4; // Jump from 44+nu to 192+nu
if (k >= frame_parms->ofdm_symbol_size)
k-=frame_parms->ofdm_symbol_size;
}
///symbol 3 [0+nushift:4:236+nushift] -- 60 mod symbols
k = frame_parms->first_carrier_offset + frame_parms->ssb_start_subcarrier + nushift;
l++;
for (int m = 84; m < NR_PBCH_DMRS_LENGTH; m++) {
#ifdef DEBUG_PBCH_DMRS
printf("m %d at k %d of l %d\n", m, k, l);
#endif
((int16_t *)txdataF)[(l*frame_parms->ofdm_symbol_size + k)<<1] = (amp * mod_dmrs[m<<1]) >> 15;
((int16_t *)txdataF)[((l*frame_parms->ofdm_symbol_size + k)<<1) + 1] = (amp * mod_dmrs[(m<<1) + 1]) >> 15;
#ifdef DEBUG_PBCH_DMRS
printf("(%d,%d)\n",
((int16_t *)txdataF)[(l*frame_parms->ofdm_symbol_size + k)<<1],
((int16_t *)txdataF)[((l*frame_parms->ofdm_symbol_size + k)<<1)+1]);
#endif
k+=4;
if (k >= frame_parms->ofdm_symbol_size)
k-=frame_parms->ofdm_symbol_size;
}
#ifdef DEBUG_PBCH_DMRS
write_output("txdataF_pbch_dmrs.m", "txdataF_pbch_dmrs", txdataF[0], frame_parms->samples_per_frame_wCP>>1, 1, 1);
#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)
{
uint32_t *pbch_e = pbch->pbch_e;
// x1 is set in lte_gold_generic
const int len = (nushift * M + 31) / 32 + (length + 31) / 32;
uint32_t *s = gold_cache(Nid, len);
// The Gold sequence is shifted by nushift* M, so we skip (nushift*M /32) double words
int goldIdx = (nushift * M + 31) / 32 - 1;
// Scrambling is now done with offset (nushift*M)%32
uint8_t 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)
goldIdx++;
pbch->pbch_a_prime ^= (((pbch->pbch_a_interleaved >> i) & 1) ^ ((s[goldIdx] >> ((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)
goldIdx++;
pbch_e[i >> 5] ^= (((s[goldIdx] >> ((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(nfapi_nr_dl_tti_ssb_pdu *ssb_pdu,
uint8_t *interleaver,
c16_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;
LOG_D(PHY, "PBCH generation started\n");
///Payload generation
NR_gNB_PBCH m_pbch;
NR_gNB_PBCH *pbch = &m_pbch;
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;
// NSA to signal no coreset0
const int ssb_sc_offset = get_softmodem_params()->sa ? config->ssb_table.ssb_subcarrier_offset.value : 31;
#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 |= (uint32_t)((ssb_index >> (5 - i)) & 1) << (29 + i); // resp. 6th, 5th and 4th bits of ssb_index
else
pbch->pbch_a |= ((ssb_sc_offset >> 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
uint64_t a_reversed = reverse_bits((uint64_t)pbch->pbch_a_prime, NR_POLAR_PBCH_PAYLOAD_BITS);
/// CRC, coding and rate matching
polar_encoder_fast (&a_reversed, (void*)pbch->pbch_e, 0, 0,
NR_POLAR_PBCH_MESSAGE_TYPE, NR_POLAR_PBCH_PAYLOAD_BITS, NR_POLAR_PBCH_AGGREGATION_LEVEL);
#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;
}
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