int main(int argc, char **argv) {
uint32_t cfi;
float cfi_corr;
int n;
if (argc < 3) {
usage(argv[0]);
exit(-1);
}
parse_args(argc,argv);
if (base_init()) {
fprintf(stderr, "Error initializing receiver\n");
exit(-1);
}
n = srslte_filesource_read(&fsrc, input_buffer, flen);
srslte_ofdm_rx_sf(&fft, input_buffer, fft_buffer);
if (fmatlab) {
fprintf(fmatlab, "infft=");
srslte_vec_fprint_c(fmatlab, input_buffer, flen);
fprintf(fmatlab, ";\n");
fprintf(fmatlab, "outfft=");
srslte_vec_sc_prod_cfc(fft_buffer, 1000.0, fft_buffer, SRSLTE_CP_NSYMB(cell.cp) * cell.nof_prb * SRSLTE_NRE);
srslte_vec_fprint_c(fmatlab, fft_buffer, SRSLTE_CP_NSYMB(cell.cp) * cell.nof_prb * SRSLTE_NRE);
fprintf(fmatlab, ";\n");
srslte_vec_sc_prod_cfc(fft_buffer, 0.001, fft_buffer, SRSLTE_CP_NSYMB(cell.cp) * cell.nof_prb * SRSLTE_NRE);
}
/* Get channel estimates for each port */
srslte_chest_dl_estimate(&chest, fft_buffer, ce, 0);
INFO("Decoding PCFICH\n", 0);
n = srslte_pcfich_decode(&pcfich, fft_buffer, ce, srslte_chest_dl_get_noise_estimate(&chest), 0, &cfi, &cfi_corr);
printf("cfi: %d, distance: %f\n", cfi, cfi_corr);
base_free();
if (n < 0) {
fprintf(stderr, "Error decoding PCFICH\n");
exit(-1);
} else if (n == 0) {
printf("Could not decode PCFICH\n");
exit(-1);
} else {
if (cfi_corr > 2.8 && cfi == 1) {
exit(0);
} else {
exit(-1);
}
}
}
/** Encodes ACK/NACK bits, modulates and inserts into resource.
* The parameter ack is an array of srslte_phich_ngroups() pointers to buffers of nof_sequences uint8_ts
*/
int srslte_phich_encode(srslte_phich_t *q, uint8_t ack, uint32_t ngroup, uint32_t nseq, uint32_t subframe,
cf_t *slot_symbols[SRSLTE_MAX_PORTS]) {
int i;
if (q == NULL || slot_symbols == NULL) {
return SRSLTE_ERROR_INVALID_INPUTS;
}
if (subframe >= SRSLTE_NSUBFRAMES_X_FRAME) {
fprintf(stderr, "Invalid nslot %d\n", subframe);
return SRSLTE_ERROR_INVALID_INPUTS;
}
if (SRSLTE_CP_ISEXT(q->cell.cp)) {
if (nseq >= SRSLTE_PHICH_EXT_NSEQUENCES) {
fprintf(stderr, "Invalid nseq %d\n", nseq);
return SRSLTE_ERROR_INVALID_INPUTS;
}
} else {
if (nseq >= SRSLTE_PHICH_NORM_NSEQUENCES) {
fprintf(stderr, "Invalid nseq %d\n", nseq);
return SRSLTE_ERROR_INVALID_INPUTS;
}
}
if (ngroup >= srslte_regs_phich_ngroups(q->regs)) {
fprintf(stderr, "Invalid ngroup %d\n", ngroup);
return SRSLTE_ERROR_INVALID_INPUTS;
}
/* Set pointers for layermapping & precoding */
cf_t *x[SRSLTE_MAX_LAYERS];
cf_t *symbols_precoding[SRSLTE_MAX_PORTS];
/* number of layers equals number of ports */
for (i = 0; i < q->cell.nof_ports; i++) {
x[i] = q->x[i];
}
for (i = 0; i < SRSLTE_MAX_PORTS; i++) {
symbols_precoding[i] = q->symbols[i];
}
/* encode ACK/NACK bit */
srslte_phich_ack_encode(ack, q->data);
srslte_mod_modulate(&q->mod, q->data, q->z, SRSLTE_PHICH_NBITS);
DEBUG("data: ", 0);
if (SRSLTE_VERBOSE_ISDEBUG())
srslte_vec_fprint_c(stdout, q->z, SRSLTE_PHICH_NBITS);
/* Spread with w */
if (SRSLTE_CP_ISEXT(q->cell.cp)) {
for (i = 0; i < SRSLTE_PHICH_EXT_MSYMB; i++) {
q->d[i] = w_ext[nseq][i % SRSLTE_PHICH_EXT_NSF]
* q->z[i / SRSLTE_PHICH_EXT_NSF];
}
} else {
for (i = 0; i < SRSLTE_PHICH_NORM_MSYMB; i++) {
q->d[i] = w_normal[nseq][i % SRSLTE_PHICH_NORM_NSF]
* q->z[i / SRSLTE_PHICH_NORM_NSF];
}
}
DEBUG("d: ", 0);
if (SRSLTE_VERBOSE_ISDEBUG())
srslte_vec_fprint_c(stdout, q->d, SRSLTE_PHICH_EXT_MSYMB);
srslte_scrambling_c(&q->seq[subframe], q->d);
/* align to REG */
if (SRSLTE_CP_ISEXT(q->cell.cp)) {
if (ngroup % 2) {
for (i = 0; i < SRSLTE_PHICH_EXT_MSYMB / 2; i++) {
q->d0[4 * i + 0] = 0;
q->d0[4 * i + 1] = 0;
q->d0[4 * i + 2] = q->d[2 * i];
q->d0[4 * i + 3] = q->d[2 * i + 1];
}
} else {
for (i = 0; i < SRSLTE_PHICH_EXT_MSYMB / 2; i++) {
q->d0[4 * i + 0] = q->d[2 * i];
q->d0[4 * i + 1] = q->d[2 * i + 1];
q->d0[4 * i + 2] = 0;
q->d0[4 * i + 3] = 0;
}
}
} else {
memcpy(q->d0, q->d, SRSLTE_PHICH_MAX_NSYMB * sizeof(cf_t));
}
DEBUG("d0: ", 0);
if (SRSLTE_VERBOSE_ISDEBUG())
srslte_vec_fprint_c(stdout, q->d0, SRSLTE_PHICH_MAX_NSYMB);
/* layer mapping & precoding */
if (q->cell.nof_ports > 1) {
srslte_layermap_diversity(q->d0, x, q->cell.nof_ports, SRSLTE_PHICH_MAX_NSYMB);
srslte_precoding_diversity(&q->precoding, x, symbols_precoding, q->cell.nof_ports,
SRSLTE_PHICH_MAX_NSYMB / q->cell.nof_ports);
/**FIXME: According to 6.9.2, Precoding for 4 tx ports is different! */
} else {
memcpy(q->symbols[0], q->d0, SRSLTE_PHICH_MAX_NSYMB * sizeof(cf_t));
}
/* mapping to resource elements */
for (i = 0; i < q->cell.nof_ports; i++) {
if (srslte_regs_phich_add(q->regs, q->symbols[i], ngroup, slot_symbols[i])
< 0) {
fprintf(stderr, "Error putting PCHICH resource elements\n");
return SRSLTE_ERROR;
}
}
return SRSLTE_SUCCESS;
}
/* Decodes the phich channel and saves the CFI in the cfi pointer.
*
* Returns 1 if successfully decoded the CFI, 0 if not and -1 on error
*/
int srslte_phich_decode(srslte_phich_t *q, cf_t *slot_symbols, cf_t *ce[SRSLTE_MAX_PORTS], float noise_estimate,
uint32_t ngroup, uint32_t nseq, uint32_t subframe, uint8_t *ack, float *distance) {
/* Set pointers for layermapping & precoding */
int i, j;
cf_t *x[SRSLTE_MAX_LAYERS];
cf_t *ce_precoding[SRSLTE_MAX_PORTS];
if (q == NULL || slot_symbols == NULL) {
return SRSLTE_ERROR_INVALID_INPUTS;
}
if (subframe >= SRSLTE_NSUBFRAMES_X_FRAME) {
fprintf(stderr, "Invalid nslot %d\n", subframe);
return SRSLTE_ERROR_INVALID_INPUTS;
}
if (SRSLTE_CP_ISEXT(q->cell.cp)) {
if (nseq >= SRSLTE_PHICH_EXT_NSEQUENCES) {
fprintf(stderr, "Invalid nseq %d\n", nseq);
return SRSLTE_ERROR_INVALID_INPUTS;
}
} else {
if (nseq >= SRSLTE_PHICH_NORM_NSEQUENCES) {
fprintf(stderr, "Invalid nseq %d\n", nseq);
return SRSLTE_ERROR_INVALID_INPUTS;
}
}
if (ngroup >= srslte_regs_phich_ngroups(q->regs)) {
fprintf(stderr, "Invalid ngroup %d\n", ngroup);
return SRSLTE_ERROR_INVALID_INPUTS;
}
DEBUG("Decoding PHICH Ngroup: %d, Nseq: %d\n", ngroup, nseq);
/* number of layers equals number of ports */
for (i = 0; i < SRSLTE_MAX_PORTS; i++) {
x[i] = q->x[i];
}
for (i = 0; i < SRSLTE_MAX_PORTS; i++) {
ce_precoding[i] = q->ce[i];
}
/* extract symbols */
if (SRSLTE_PHICH_MAX_NSYMB
!= srslte_regs_phich_get(q->regs, slot_symbols, q->symbols[0], ngroup)) {
fprintf(stderr, "There was an error getting the phich symbols\n");
return SRSLTE_ERROR;
}
/* extract channel estimates */
for (i = 0; i < q->cell.nof_ports; i++) {
if (SRSLTE_PHICH_MAX_NSYMB != srslte_regs_phich_get(q->regs, ce[i], q->ce[i], ngroup)) {
fprintf(stderr, "There was an error getting the phich symbols\n");
return SRSLTE_ERROR;
}
}
/* in control channels, 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->d0, SRSLTE_PHICH_MAX_NSYMB, noise_estimate);
} else {
srslte_predecoding_diversity(&q->precoding, q->symbols[0], ce_precoding, x,
q->cell.nof_ports, SRSLTE_PHICH_MAX_NSYMB, noise_estimate);
srslte_layerdemap_diversity(x, q->d0, q->cell.nof_ports,
SRSLTE_PHICH_MAX_NSYMB / q->cell.nof_ports);
}
DEBUG("Recv!!: \n", 0);
DEBUG("d0: ", 0);
if (SRSLTE_VERBOSE_ISDEBUG())
srslte_vec_fprint_c(stdout, q->d0, SRSLTE_PHICH_MAX_NSYMB);
if (SRSLTE_CP_ISEXT(q->cell.cp)) {
if (ngroup % 2) {
for (i = 0; i < SRSLTE_PHICH_EXT_MSYMB / 2; i++) {
q->d[2 * i + 0] = q->d0[4 * i + 2];
q->d[2 * i + 1] = q->d0[4 * i + 3];
}
} else {
for (i = 0; i < SRSLTE_PHICH_EXT_MSYMB / 2; i++) {
q->d[2 * i + 0] = q->d0[4 * i];
q->d[2 * i + 1] = q->d0[4 * i + 1];
}
}
} else {
memcpy(q->d, q->d0, SRSLTE_PHICH_MAX_NSYMB * sizeof(cf_t));
}
DEBUG("d: ", 0);
if (SRSLTE_VERBOSE_ISDEBUG())
srslte_vec_fprint_c(stdout, q->d, SRSLTE_PHICH_EXT_MSYMB);
srslte_scrambling_c(&q->seq[subframe], q->d);
/* De-spreading */
if (SRSLTE_CP_ISEXT(q->cell.cp)) {
for (i = 0; i < SRSLTE_PHICH_NBITS; i++) {
q->z[i] = 0;
for (j = 0; j < SRSLTE_PHICH_EXT_NSF; j++) {
q->z[i] += conjf(w_ext[nseq][j])
* q->d[i * SRSLTE_PHICH_EXT_NSF + j] / SRSLTE_PHICH_EXT_NSF;
}
}
} else {
for (i = 0; i < SRSLTE_PHICH_NBITS; i++) {
q->z[i] = 0;
for (j = 0; j < SRSLTE_PHICH_NORM_NSF; j++) {
q->z[i] += conjf(w_normal[nseq][j])
* q->d[i * SRSLTE_PHICH_NORM_NSF + j] / SRSLTE_PHICH_NORM_NSF;
}
}
}
DEBUG("z: ", 0);
if (SRSLTE_VERBOSE_ISDEBUG())
srslte_vec_fprint_c(stdout, q->z, SRSLTE_PHICH_NBITS);
srslte_demod_soft_demodulate(SRSLTE_MOD_BPSK, q->z, q->data_rx, SRSLTE_PHICH_NBITS);
if (ack) {
*ack = srslte_phich_ack_decode(q->data_rx, distance);
}
return SRSLTE_SUCCESS;
}
