/** Decodes the PDSCH from the received symbols
*/
int srslte_pdsch_decode(srslte_pdsch_t *q,
srslte_pdsch_cfg_t *cfg, srslte_softbuffer_rx_t *softbuffers[SRSLTE_MAX_CODEWORDS],
cf_t *sf_symbols[SRSLTE_MAX_PORTS], cf_t *ce[SRSLTE_MAX_PORTS][SRSLTE_MAX_PORTS],
float noise_estimate, uint16_t rnti, uint8_t *data[SRSLTE_MAX_CODEWORDS],
bool acks[SRSLTE_MAX_CODEWORDS])
{
/* Set pointers for layermapping & precoding */
uint32_t i;
cf_t *x[SRSLTE_MAX_LAYERS];
if (q != NULL &&
sf_symbols != NULL &&
data != NULL &&
cfg != NULL)
{
uint32_t nof_tb = SRSLTE_RA_DL_GRANT_NOF_TB(&cfg->grant);
INFO("Decoding PDSCH SF: %d, RNTI: 0x%x, NofSymbols: %d, C_prb=%d, mimo_type=%s, nof_layers=%d, nof_tb=%d\n",
cfg->sf_idx, rnti, cfg->nbits[0].nof_re, cfg->grant.nof_prb, srslte_mod_string(cfg->grant.mcs->mod), cfg->nof_layers, nof_tb);
// Extract Symbols and Channel Estimates
for (int j=0;j<q->nof_rx_antennas;j++) {
int n = srslte_pdsch_get(q, sf_symbols[j], q->symbols[j], &cfg->grant, cfg->nbits[0].lstart, cfg->sf_idx);
if (n != cfg->nbits[0].nof_re) {
fprintf(stderr, "Error expecting %d symbols but got %d\n", cfg->nbits[0].nof_re, n);
return SRSLTE_ERROR;
}
for (i = 0; i < q->cell.nof_ports; i++) {
n = srslte_pdsch_get(q, ce[i][j], q->ce[i][j], &cfg->grant, cfg->nbits[0].lstart, cfg->sf_idx);
if (n != cfg->nbits[0].nof_re) {
fprintf(stderr, "Error expecting %d symbols but got %d\n", cfg->nbits[0].nof_re, n);
return SRSLTE_ERROR;
}
}
}
// Prepare layers
int nof_symbols [SRSLTE_MAX_CODEWORDS];
nof_symbols[0] = cfg->nbits[0].nof_re * nof_tb / cfg->nof_layers;
nof_symbols[1] = cfg->nbits[1].nof_re * nof_tb / cfg->nof_layers;
if (cfg->nof_layers == nof_tb) {
/* Skip layer demap */
for (i = 0; i < cfg->nof_layers; i++) {
x[i] = q->d[i];
}
} else {
/* number of layers equals number of ports */
for (i = 0; i < cfg->nof_layers; i++) {
x[i] = q->x[i];
}
memset(&x[cfg->nof_layers], 0, sizeof(cf_t*) * (SRSLTE_MAX_LAYERS - cfg->nof_layers));
}
float pdsch_scaling = 1.0f;
if (q->rho_a != 0.0f) {
pdsch_scaling = q->rho_a;
}
// Pre-decoder
if (srslte_predecoding_type(q->symbols, q->ce, x, q->nof_rx_antennas, q->cell.nof_ports, cfg->nof_layers,
cfg->codebook_idx, cfg->nbits[0].nof_re, cfg->mimo_type, pdsch_scaling, noise_estimate)<0) {
DEBUG("Error predecoding\n");
return SRSLTE_ERROR;
}
// Layer demapping only if necessary
if (cfg->nof_layers != nof_tb) {
srslte_layerdemap_type(x, q->d, cfg->nof_layers, nof_tb,
nof_symbols[0], nof_symbols, cfg->mimo_type);
}
/* Codeword decoding: Implementation of 3GPP 36.212 Table 5.3.3.1.5-1 and Table 5.3.3.1.5-2 */
uint32_t cw_idx = (nof_tb == SRSLTE_MAX_TB && cfg->tb_cw_swap) ? 1 : 0;
for (uint32_t tb_idx = 0; tb_idx < SRSLTE_MAX_TB; tb_idx++) {
/* Decode only if transport block is enabled and the default ACK is not true */
if (cfg->grant.tb_en[tb_idx]) {
if (!acks[tb_idx]) {
int ret = srslte_pdsch_codeword_decode(q, cfg, softbuffers[tb_idx], rnti, data[tb_idx], cw_idx, tb_idx, &acks[tb_idx]);
/* Check if there has been any execution error */
if (ret) {
return ret;
}
}
cw_idx = (cw_idx + 1) % SRSLTE_MAX_CODEWORDS;
}
}
pdsch_decode_debug(q, cfg, sf_symbols, ce);
return SRSLTE_SUCCESS;
} else {
return SRSLTE_ERROR_INVALID_INPUTS;
}
}
int main(int argc, char **argv) {
int i, j;
float mse;
cf_t *x[SRSLTE_MAX_LAYERS], *r[SRSLTE_MAX_PORTS], *y[SRSLTE_MAX_PORTS], *h[SRSLTE_MAX_PORTS],
*xr[SRSLTE_MAX_LAYERS];
srslte_mimo_type_t type;
srslte_precoding_t precoding;
parse_args(argc, argv);
if (nof_ports > SRSLTE_MAX_PORTS || nof_layers > SRSLTE_MAX_LAYERS) {
fprintf(stderr, "Invalid number of layers or ports\n");
exit(-1);
}
if (srslte_str2mimotype(mimo_type_name, &type)) {
fprintf(stderr, "Invalid MIMO type %s\n", mimo_type_name);
exit(-1);
}
for (i = 0; i < nof_layers; i++) {
x[i] = srslte_vec_malloc(sizeof(cf_t) * nof_symbols);
if (!x[i]) {
perror("srslte_vec_malloc");
exit(-1);
}
xr[i] = srslte_vec_malloc(sizeof(cf_t) * nof_symbols);
if (!xr[i]) {
perror("srslte_vec_malloc");
exit(-1);
}
}
for (i = 0; i < nof_ports; i++) {
y[i] = srslte_vec_malloc(sizeof(cf_t) * nof_symbols * nof_layers);
// TODO: The number of symbols per port is different in spatial multiplexing.
if (!y[i]) {
perror("srslte_vec_malloc");
exit(-1);
}
h[i] = srslte_vec_malloc(sizeof(cf_t) * nof_symbols * nof_layers);
if (!h[i]) {
perror("srslte_vec_malloc");
exit(-1);
}
}
/* only 1 receiver antenna supported now */
r[0] = srslte_vec_malloc(sizeof(cf_t) * nof_symbols * nof_layers);
if (!r[0]) {
perror("srslte_vec_malloc");
exit(-1);
}
/* generate random data */
for (i = 0; i < nof_layers; i++) {
for (j = 0; j < nof_symbols; j++) {
x[i][j] = (2*(rand()%2)-1+(2*(rand()%2)-1)*_Complex_I)/sqrt(2);
}
}
if (srslte_precoding_init(&precoding, nof_symbols * nof_layers)) {
fprintf(stderr, "Error initializing precoding\n");
exit(-1);
}
/* precoding */
if (srslte_precoding_type(&precoding, x, y, nof_layers, nof_ports, nof_symbols, type) < 0) {
fprintf(stderr, "Error layer mapper encoder\n");
exit(-1);
}
/* generate channel */
for (i = 0; i < nof_ports; i++) {
for (j = 0; j < nof_symbols; j++) {
h[i][nof_layers*j] = (float) rand()/RAND_MAX+((float) rand()/RAND_MAX)*_Complex_I;
// assume the channel is time-invariant in nlayer consecutive symbols
for (int k=0;k<nof_layers;k++) {
h[i][nof_layers*j+k] = h[i][nof_layers*j];
}
}
}
/* pass signal through channel
(we are in the frequency domain so it's a multiplication) */
/* there's only one receiver antenna, signals from different transmitter
* ports are simply combined at the receiver
*/
for (j = 0; j < nof_symbols * nof_layers; j++) {
r[0][j] = 0;
for (i = 0; i < nof_ports; i++) {
r[0][j] += y[i][j] * h[i][j];
}
}
/* predecoding / equalization */
struct timeval t[3];
gettimeofday(&t[1], NULL);
if (srslte_predecoding_type(&precoding, r[0], h, xr, nof_ports, nof_layers,
nof_symbols * nof_layers, type, 0) < 0) {
fprintf(stderr, "Error layer mapper encoder\n");
exit(-1);
}
gettimeofday(&t[2], NULL);
get_time_interval(t);
printf("Execution Time: %d us\n", t[0].tv_usec);
/* check errors */
mse = 0;
for (i = 0; i < nof_layers; i++) {
for (j = 0; j < nof_symbols; j++) {
mse += cabsf(xr[i][j] - x[i][j]);
}
}
printf("MSE: %f\n", mse/ nof_layers / nof_symbols );
if (mse / nof_layers / nof_symbols > MSE_THRESHOLD) {
exit(-1);
}
for (i = 0; i < nof_layers; i++) {
free(x[i]);
free(xr[i]);
}
for (i = 0; i < nof_ports; i++) {
free(y[i]);
free(h[i]);
}
free(r[0]);
srslte_precoding_free(&precoding);
printf("Ok\n");
exit(0);
}
int main(int argc, char **argv) {
int i, j, k, nof_errors = 0, ret = SRSLTE_SUCCESS;
float mse;
cf_t *x[SRSLTE_MAX_LAYERS], *r[SRSLTE_MAX_PORTS], *y[SRSLTE_MAX_PORTS], *h[SRSLTE_MAX_PORTS][SRSLTE_MAX_PORTS],
*xr[SRSLTE_MAX_LAYERS];
srslte_mimo_type_t type;
parse_args(argc, argv);
/* Check input ranges */
if (nof_tx_ports > SRSLTE_MAX_PORTS || nof_rx_ports > SRSLTE_MAX_PORTS || nof_layers > SRSLTE_MAX_LAYERS) {
fprintf(stderr, "Invalid number of layers or ports\n");
exit(-1);
}
/* Parse MIMO Type */
if (srslte_str2mimotype(mimo_type_name, &type)) {
fprintf(stderr, "Invalid MIMO type %s\n", mimo_type_name);
exit(-1);
}
/* Check scenario conditions are OK */
switch (type) {
case SRSLTE_MIMO_TYPE_TX_DIVERSITY:
nof_re = nof_layers*nof_symbols;
break;
case SRSLTE_MIMO_TYPE_SPATIAL_MULTIPLEX:
nof_re = nof_symbols;
break;
case SRSLTE_MIMO_TYPE_CDD:
nof_re = nof_symbols*nof_tx_ports/nof_layers;
if (nof_rx_ports != 2 || nof_tx_ports != 2) {
fprintf(stderr, "CDD nof_tx_ports=%d nof_rx_ports=%d is not currently supported\n", nof_tx_ports, nof_rx_ports);
exit(-1);
}
break;
default:
nof_re = nof_symbols*nof_layers;
}
/* Allocate x and xr (received symbols) in memory for each layer */
for (i = 0; i < nof_layers; i++) {
/* Source data */
x[i] = srslte_vec_malloc(sizeof(cf_t) * nof_symbols);
if (!x[i]) {
perror("srslte_vec_malloc");
exit(-1);
}
/* Sink data */
xr[i] = srslte_vec_malloc(sizeof(cf_t) * nof_symbols);
if (!xr[i]) {
perror("srslte_vec_malloc");
exit(-1);
}
}
/* Allocate y in memory for tx each port */
for (i = 0; i < nof_tx_ports; i++) {
y[i] = srslte_vec_malloc(sizeof(cf_t) * nof_re);
if (!y[i]) {
perror("srslte_vec_malloc");
exit(-1);
}
}
/* Allocate h in memory for each cross channel and layer */
for (i = 0; i < nof_tx_ports; i++) {
for (j = 0; j < nof_rx_ports; j++) {
h[i][j] = srslte_vec_malloc(sizeof(cf_t) * nof_re);
if (!h[i][j]) {
perror("srslte_vec_malloc");
exit(-1);
}
}
}
/* Allocate r */
for (i = 0; i < nof_rx_ports; i++) {
r[i] = srslte_vec_malloc(sizeof(cf_t) * nof_re);
if (!r[i]) {
perror("srslte_vec_malloc");
exit(-1);
}
}
/* Generate source random data */
for (i = 0; i < nof_layers; i++) {
for (j = 0; j < nof_symbols; j++) {
x[i][j] = (2 * (rand() % 2) - 1 + (2 * (rand() % 2) - 1) * _Complex_I) / sqrt(2);
}
}
/* Execute Precoding (Tx) */
if (srslte_precoding_type(x, y, nof_layers, nof_tx_ports, codebook_idx, nof_symbols, scaling, type) < 0) {
fprintf(stderr, "Error layer mapper encoder\n");
exit(-1);
}
/* generate channel */
populate_channel(type, h);
/* pass signal through channel
(we are in the frequency domain so it's a multiplication) */
for (i = 0; i < nof_rx_ports; i++) {
for (k = 0; k < nof_re; k++) {
r[i][k] = (cf_t) (0.0 + 0.0 * _Complex_I);
for (j = 0; j < nof_tx_ports; j++) {
r[i][k] += y[j][k] * h[j][i][k];
}
}
}
awgn(r, (uint32_t) nof_re, snr_db);
/* If CDD or Spatial muliplex choose decoder */
if (strncmp(decoder_type_name, "zf", 16) == 0) {
srslte_predecoding_set_mimo_decoder(SRSLTE_MIMO_DECODER_ZF);
} else if (strncmp(decoder_type_name, "mmse", 16) == 0) {
srslte_predecoding_set_mimo_decoder(SRSLTE_MIMO_DECODER_MMSE);
} else {
ret = SRSLTE_ERROR;
goto quit;
}
/* predecoding / equalization */
struct timeval t[3];
gettimeofday(&t[1], NULL);
srslte_predecoding_type(r, h, xr, NULL, nof_rx_ports, nof_tx_ports, nof_layers,
codebook_idx, nof_re, type, scaling, powf(10, -snr_db / 10));
gettimeofday(&t[2], NULL);
get_time_interval(t);
/* check errors */
mse = 0;
for (i = 0; i < nof_layers; i++) {
for (j = 0; j < nof_symbols; j++) {
mse += cabsf(xr[i][j] - x[i][j]);
if ((crealf(xr[i][j]) > 0) != (crealf(x[i][j]) > 0)) {
nof_errors ++;
}
if ((cimagf(xr[i][j]) > 0) != (cimagf(x[i][j]) > 0)) {
nof_errors ++;
}
}
}
printf("SNR: %5.1fdB;\tExecution time: %5ldus;\tMSE: %.6f;\tBER: %.6f\n", snr_db, t[0].tv_usec,
mse / nof_layers / nof_symbols, (float) nof_errors / (4.0f * nof_re));
if (mse / nof_layers / nof_symbols > MSE_THRESHOLD) {
ret = SRSLTE_ERROR;
}
quit:
/* Free all data */
for (i = 0; i < nof_layers; i++) {
free(x[i]);
free(xr[i]);
}
for (i = 0; i < nof_rx_ports; i++) {
free(r[i]);
}
for (i = 0; i < nof_rx_ports; i++) {
for (j = 0; j < nof_tx_ports; j++) {
free(h[j][i]);
}
}
exit(ret);
}
