/** Converts the MIB message to symbols mapped to SLOT #1 ready for transmission
*/
void pbch_encode(pbch_t *q, pbch_mib_t *mib,
cf_t *slot1_symbols[MAX_PORTS_CTRL], int nof_ports) {
int i;
int nof_bits = 2 * q->nof_symbols;
assert(nof_ports <= MAX_PORTS_CTRL);
/* Set pointers for layermapping & precoding */
cf_t *x[MAX_LAYERS];
/* number of layers equals number of ports */
for (i = 0; i < nof_ports; i++) {
x[i] = q->pbch_x[i];
}
memset(&x[nof_ports], 0, sizeof(cf_t*) * (MAX_LAYERS - nof_ports));
if (q->frame_idx == 0) {
/* pack MIB */
pbch_mib_pack(mib, q->data);
/* encode & modulate */
crc_attach(&q->crc, q->data, 24);
crc_set_mask(q->data, nof_ports);
convcoder_encode(&q->encoder, q->data, q->data_enc, 40);
rm_conv_tx(q->data_enc, 120, q->pbch_rm_b, 4 * nof_bits);
}
scrambling_b_offset(&q->seq_pbch, &q->pbch_rm_b[q->frame_idx * nof_bits],
q->frame_idx * nof_bits, nof_bits);
mod_modulate(&q->mod, &q->pbch_rm_b[q->frame_idx * nof_bits], q->pbch_d,
nof_bits);
/* layer mapping & precoding */
if (nof_ports > 1) {
layermap_diversity(q->pbch_d, x, nof_ports, q->nof_symbols);
precoding_diversity(x, q->pbch_symbols, nof_ports,
q->nof_symbols / nof_ports);
} else {
memcpy(q->pbch_symbols[0], q->pbch_d, q->nof_symbols * sizeof(cf_t));
}
/* mapping to resource elements */
for (i = 0; i < nof_ports; i++) {
pbch_put(q->pbch_symbols[i], slot1_symbols[i], q->nof_prb, q->cp,
q->cell_id);
}
q->frame_idx++;
if (q->frame_idx == 4) {
q->frame_idx = 0;
}
}
/** Converts the MIB message to symbols mapped to SLOT #1 ready for transmission
*/
int pbch_encode(pbch_t *q, pbch_mib_t *mib, cf_t *slot1_symbols[MAX_PORTS]) {
int i;
int nof_bits;
cf_t *x[MAX_LAYERS];
if (q != NULL &&
mib != NULL)
{
for (i=0;i<q->cell.nof_ports;i++) {
if (slot1_symbols[i] == NULL) {
return LIBLTE_ERROR_INVALID_INPUTS;
}
}
/* Set pointers for layermapping & precoding */
nof_bits = 2 * q->nof_symbols;
/* number of layers equals number of ports */
for (i = 0; i < q->cell.nof_ports; i++) {
x[i] = q->pbch_x[i];
}
memset(&x[q->cell.nof_ports], 0, sizeof(cf_t*) * (MAX_LAYERS - q->cell.nof_ports));
if (q->frame_idx == 0) {
/* pack MIB */
pbch_mib_pack(mib, q->data);
/* encode & modulate */
crc_attach(&q->crc, q->data, 24);
crc_set_mask(q->data, q->cell.nof_ports);
convcoder_encode(&q->encoder, q->data, q->data_enc, 40);
rm_conv_tx(q->data_enc, 120, q->pbch_rm_b, 4 * nof_bits);
}
scrambling_b_offset(&q->seq_pbch, &q->pbch_rm_b[q->frame_idx * nof_bits],
q->frame_idx * nof_bits, nof_bits);
mod_modulate(&q->mod, &q->pbch_rm_b[q->frame_idx * nof_bits], q->pbch_d,
nof_bits);
/* layer mapping & precoding */
if (q->cell.nof_ports > 1) {
layermap_diversity(q->pbch_d, x, q->cell.nof_ports, q->nof_symbols);
precoding_diversity(x, q->pbch_symbols, q->cell.nof_ports,
q->nof_symbols / q->cell.nof_ports);
} else {
memcpy(q->pbch_symbols[0], q->pbch_d, q->nof_symbols * sizeof(cf_t));
}
/* mapping to resource elements */
for (i = 0; i < q->cell.nof_ports; i++) {
pbch_put(q->pbch_symbols[i], slot1_symbols[i], q->cell);
}
q->frame_idx++;
if (q->frame_idx == 4) {
q->frame_idx = 0;
}
return LIBLTE_SUCCESS;
} else {
return LIBLTE_ERROR_INVALID_INPUTS;
}
}
int main(int argc, char **argv) {
viterbi_t dec;
convcoder_t cod;
modem_table_t modem;
demod_soft_t demod;
int frame_cnt;
float *llr;
char *data_tx, *data_rx, *symbols;
cf_t *iq;
int i;
parse_args(argc,argv);
if (!seed) {
seed = time(NULL);
}
srand(seed);
int coded_length = 3 * (frame_length + ((tail_biting)?0:6));
printf("Convolutional Code 1/3 K=7 Test\n");
printf(" Frame length: %d\n", frame_length);
printf(" Codeword length: %d\n", coded_length);
printf(" Tail bitting: %s\n", tail_biting?"yes":"no");
printf(" EbNo: %.2f\n", ebno_db);
data_tx = malloc(frame_length * sizeof(char));
if (!data_tx) {
perror("malloc");
exit(-1);
}
data_rx = malloc(frame_length * sizeof(char));
if (!data_rx) {
perror("malloc");
exit(-1);
}
symbols = malloc(coded_length * sizeof(char));
if (!symbols) {
perror("malloc");
exit(-1);
}
llr = malloc(coded_length * sizeof(float));
if (!llr) {
perror("malloc");
exit(-1);
}
iq = malloc(coded_length * sizeof(cf_t));
if (!iq) {
perror("malloc");
exit(-1);
}
cod.K = 7;
cod.R = 3;
cod.tail_biting = tail_biting;
cod.framelength = frame_length;
cod.poly[0] = 0x6D;
cod.poly[1] = 0x4F;
cod.poly[2] = 0x57;
float var = sqrt(pow(10,-ebno_db/10));
modem_table_init(&modem);
modem_table_std(&modem, LTE_QPSK, true);
demod_soft_init(&demod);
demod_soft_table_set(&demod, &modem);
demod_soft_alg_set(&demod, APPROX);
demod_soft_sigma_set(&demod, var);
viterbi_init(&dec, viterbi_37, cod.poly, frame_length, tail_biting);
/* read all file or nof_frames */
frame_cnt = 0;
unsigned int errors=0;
while (frame_cnt < nof_slots) {
/* generate data_tx */
for (i=0;i<frame_length;i++) {
data_tx[i] = message[i];
}
convcoder_encode(&cod, data_tx, symbols);
bit_fprint(stdout, symbols, 120);
mod_modulate(&modem, symbols, iq, coded_length);
if (ebno_db < 100.0) {
ch_awgn(iq, iq, var, coded_length/2);
}
demod_soft_demodulate(&demod, iq, llr, coded_length/2);
viterbi_decode(&dec, llr, data_rx);
errors += bit_diff(data_tx, data_rx, frame_length);
frame_cnt++;
}
printf("BER:\t%g\t%u errors\n", (float) errors/(frame_cnt*frame_length), errors);
viterbi_free(&dec);
free(data_tx);
free(symbols);
free(iq);
free(llr);
free(data_rx);
printf("Done\n");
exit(0);
}