/* Precalculate the PDSCH scramble sequences for a given RNTI. This function takes a while
* to execute, so shall be called once the final C-RNTI has been allocated for the session.
*/
int srslte_pdsch_set_rnti(srslte_pdsch_t *q, uint16_t rnti) {
uint32_t rnti_idx = q->is_ue?0:rnti;
if (!q->users[rnti_idx] || q->is_ue) {
if (!q->users[rnti_idx]) {
q->users[rnti_idx] = calloc(1, sizeof(srslte_pdsch_user_t));
if(!q->users[rnti_idx]) {
perror("calloc");
return -1;
}
}
for (int i = 0; i < SRSLTE_NSUBFRAMES_X_FRAME; i++) {
for (int j = 0; j < SRSLTE_MAX_CODEWORDS; j++) {
if (srslte_sequence_pdsch(&q->users[rnti_idx]->seq[j][i], rnti, j, 2 * i, q->cell.id,
q->max_re * srslte_mod_bits_x_symbol(SRSLTE_MOD_64QAM)))
{
fprintf(stderr, "Error initializing PDSCH scrambling sequence\n");
srslte_pdsch_free_rnti(q, rnti);
return SRSLTE_ERROR;
}
}
}
q->ue_rnti = rnti;
q->users[rnti_idx]->cell_id = q->cell.id;
q->users[rnti_idx]->sequence_generated = true;
} else {
fprintf(stderr, "Error generating PDSCH sequence: rnti=0x%x already generated\n", rnti);
}
return SRSLTE_SUCCESS;
}
int init_sequence(srslte_sequence_t *seq, char *name) {
if (!strcmp(name, "PBCH")) {
return srslte_sequence_pbch(seq, cp, cell_id);
} else if (!strcmp(name, "PDSCH")) {
return srslte_sequence_pdsch(seq, 1234, 0, 0, cell_id, nof_bits);
} else {
fprintf(stderr, "Unsupported sequence name %s\n", name);
return -1;
}
}
/* Precalculate the PDSCH scramble sequences for a given RNTI. This function takes a while
* to execute, so shall be called once the final C-RNTI has been allocated for the session.
*/
int srslte_pdsch_set_rnti(srslte_pdsch_t *q, uint16_t rnti) {
uint32_t i;
for (i = 0; i < SRSLTE_NSUBFRAMES_X_FRAME; i++) {
if (srslte_sequence_pdsch(&q->seq[i], rnti, 0, 2 * i, q->cell.id,
q->max_re * srslte_mod_bits_x_symbol(SRSLTE_MOD_64QAM))) {
return SRSLTE_ERROR;
}
}
q->rnti_is_set = true;
q->rnti = rnti;
return SRSLTE_SUCCESS;
}
static srslte_sequence_t *get_user_sequence(srslte_pdsch_t *q, uint16_t rnti,
uint32_t codeword_idx, uint32_t sf_idx, uint32_t len)
{
uint32_t rnti_idx = q->is_ue?0:rnti;
// The scrambling sequence is pregenerated for all RNTIs in the eNodeB but only for C-RNTI in the UE
if (q->users[rnti_idx] && q->users[rnti_idx]->sequence_generated &&
q->users[rnti_idx]->cell_id == q->cell.id &&
q->ue_rnti == rnti &&
((rnti >= SRSLTE_CRNTI_START && rnti < SRSLTE_CRNTI_END) || !q->is_ue))
{
return &q->users[rnti_idx]->seq[codeword_idx][sf_idx];
} else {
srslte_sequence_pdsch(&q->tmp_seq, rnti, codeword_idx, 2 * sf_idx, q->cell.id, len);
return &q->tmp_seq;
}
}
/** Converts the PDSCH data bits to symbols mapped to the slot ready for transmission
*/
int srslte_pdsch_encode_rnti(srslte_pdsch_t *q,
srslte_pdsch_cfg_t *cfg, srslte_softbuffer_tx_t *softbuffer,
uint8_t *data, uint16_t rnti, cf_t *sf_symbols[SRSLTE_MAX_PORTS])
{
int i;
/* Set pointers for layermapping & precoding */
cf_t *x[SRSLTE_MAX_LAYERS];
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
data != NULL &&
cfg != NULL)
{
for (i=0; i<q->cell.nof_ports; i++) {
if (sf_symbols[i] == NULL) {
return SRSLTE_ERROR_INVALID_INPUTS;
}
}
if (cfg->grant.mcs.tbs == 0) {
return SRSLTE_ERROR_INVALID_INPUTS;
}
if (cfg->nbits.nof_re > q->max_re) {
fprintf(stderr,
"Error too many RE per subframe (%d). PDSCH configured for %d RE (%d PRB)\n",
cfg->nbits.nof_re, q->max_re, q->cell.nof_prb);
return SRSLTE_ERROR_INVALID_INPUTS;
}
INFO("Encoding PDSCH SF: %d, Mod %s, NofBits: %d, NofSymbols: %d, NofBitsE: %d, rv_idx: %d\n",
cfg->sf_idx, srslte_mod_string(cfg->grant.mcs.mod), cfg->grant.mcs.tbs,
cfg->nbits.nof_re, cfg->nbits.nof_bits, cfg->rv);
/* number of layers equals number of ports */
for (i = 0; i < q->cell.nof_ports; i++) {
x[i] = q->x[i];
}
memset(&x[q->cell.nof_ports], 0, sizeof(cf_t*) * (SRSLTE_MAX_LAYERS - q->cell.nof_ports));
if (srslte_dlsch_encode(&q->dl_sch, cfg, softbuffer, data, q->e)) {
fprintf(stderr, "Error encoding TB\n");
return SRSLTE_ERROR;
}
if (rnti != q->rnti) {
srslte_sequence_t seq;
if (srslte_sequence_pdsch(&seq, rnti, 0, 2 * cfg->sf_idx, q->cell.id, cfg->nbits.nof_bits)) {
return SRSLTE_ERROR;
}
srslte_scrambling_bytes_offset(&seq, (uint8_t*) q->e, 0, cfg->nbits.nof_bits);
srslte_sequence_free(&seq);
} else {
srslte_scrambling_bytes_offset(&q->seq[cfg->sf_idx], (uint8_t*) q->e, 0, cfg->nbits.nof_bits);
}
srslte_mod_modulate_bytes(&q->mod[cfg->grant.mcs.mod], (uint8_t*) q->e, q->d, cfg->nbits.nof_bits);
/* TODO: only diversity supported */
if (q->cell.nof_ports > 1) {
srslte_layermap_diversity(q->d, x, q->cell.nof_ports, cfg->nbits.nof_re);
srslte_precoding_diversity(&q->precoding, x, q->symbols, q->cell.nof_ports,
cfg->nbits.nof_re / q->cell.nof_ports);
} else {
memcpy(q->symbols[0], q->d, cfg->nbits.nof_re * sizeof(cf_t));
}
/* mapping to resource elements */
for (i = 0; i < q->cell.nof_ports; i++) {
srslte_pdsch_put(q, q->symbols[i], sf_symbols[i], &cfg->grant, cfg->nbits.lstart, cfg->sf_idx);
}
ret = SRSLTE_SUCCESS;
}
return ret;
}
/** Decodes the PDSCH from the received symbols
*/
int srslte_pdsch_decode_rnti(srslte_pdsch_t *q,
srslte_pdsch_cfg_t *cfg, srslte_softbuffer_rx_t *softbuffer,
cf_t *sf_symbols, cf_t *ce[SRSLTE_MAX_PORTS], float noise_estimate,
uint16_t rnti, uint8_t *data)
{
/* Set pointers for layermapping & precoding */
uint32_t i, n;
cf_t *x[SRSLTE_MAX_LAYERS];
if (q != NULL &&
sf_symbols != NULL &&
data != NULL &&
cfg != NULL)
{
INFO("Decoding PDSCH SF: %d, RNTI: 0x%x, Mod %s, TBS: %d, NofSymbols: %d, NofBitsE: %d, rv_idx: %d, C_prb=%d\n",
cfg->sf_idx, rnti, srslte_mod_string(cfg->grant.mcs.mod), cfg->grant.mcs.tbs, cfg->nbits.nof_re,
cfg->nbits.nof_bits, cfg->rv, cfg->grant.nof_prb);
/* number of layers equals number of ports */
for (i = 0; i < q->cell.nof_ports; i++) {
x[i] = q->x[i];
}
memset(&x[q->cell.nof_ports], 0, sizeof(cf_t*) * (SRSLTE_MAX_LAYERS - q->cell.nof_ports));
/* extract symbols */
n = srslte_pdsch_get(q, sf_symbols, q->symbols[0], &cfg->grant, cfg->nbits.lstart, cfg->sf_idx);
if (n != cfg->nbits.nof_re) {
fprintf(stderr, "Error expecting %d symbols but got %d\n", cfg->nbits.nof_re, n);
return SRSLTE_ERROR;
}
/* extract channel estimates */
for (i = 0; i < q->cell.nof_ports; i++) {
n = srslte_pdsch_get(q, ce[i], q->ce[i], &cfg->grant, cfg->nbits.lstart, cfg->sf_idx);
if (n != cfg->nbits.nof_re) {
fprintf(stderr, "Error expecting %d symbols but got %d\n", cfg->nbits.nof_re, n);
return SRSLTE_ERROR;
}
}
/* TODO: only diversity is supported */
if (q->cell.nof_ports == 1) {
/* no need for layer demapping */
srslte_predecoding_single(q->symbols[0], q->ce[0], q->d, cfg->nbits.nof_re, noise_estimate);
} else {
srslte_predecoding_diversity(&q->precoding, q->symbols[0], q->ce, x, q->cell.nof_ports,
cfg->nbits.nof_re, noise_estimate);
srslte_layerdemap_diversity(x, q->d, q->cell.nof_ports,
cfg->nbits.nof_re / q->cell.nof_ports);
}
if (SRSLTE_VERBOSE_ISDEBUG()) {
DEBUG("SAVED FILE pdsch_symbols.dat: symbols after equalization\n",0);
srslte_vec_save_file("pdsch_symbols.dat", q->d, cfg->nbits.nof_re*sizeof(cf_t));
}
/* demodulate symbols
* The MAX-log-MAP algorithm used in turbo decoding is unsensitive to SNR estimation,
* thus we don't need tot set it in the LLRs normalization
*/
srslte_demod_soft_demodulate_s(cfg->grant.mcs.mod, q->d, q->e, cfg->nbits.nof_re);
/* descramble */
if (rnti != q->rnti) {
srslte_sequence_t seq;
if (srslte_sequence_pdsch(&seq, rnti, 0, 2 * cfg->sf_idx, q->cell.id, cfg->nbits.nof_bits)) {
return SRSLTE_ERROR;
}
srslte_scrambling_s_offset(&seq, q->e, 0, cfg->nbits.nof_bits);
srslte_sequence_free(&seq);
} else {
srslte_scrambling_s_offset(&q->seq[cfg->sf_idx], q->e, 0, cfg->nbits.nof_bits);
}
if (SRSLTE_VERBOSE_ISDEBUG()) {
DEBUG("SAVED FILE llr.dat: LLR estimates after demodulation and descrambling\n",0);
srslte_vec_save_file("llr.dat", q->e, cfg->nbits.nof_bits*sizeof(int16_t));
}
return srslte_dlsch_decode(&q->dl_sch, cfg, softbuffer, q->e, data);
} else {
return SRSLTE_ERROR_INVALID_INPUTS;
}
}
