limiting prach search space to number of prachs set in sib2

lib/include/srslte/phy/phch/prach.h

@@ -93,7 +93,7 @@ typedef struct SRSLTE_API {
   uint32_t deadzone;
   float    peak_values[65];
   uint32_t peak_offsets[65];
-
+  uint32_t            num_ra_preambles;
   srslte_tdd_config_t tdd_config;
   uint32_t            current_prach_idx;
 
@@ -114,6 +114,7 @@ typedef struct {
   uint32_t            root_seq_idx;
   uint32_t            zero_corr_zone;
   uint32_t            freq_offset;
+  uint32_t            num_ra_preambles;
   bool                hs_flag;
   srslte_tdd_config_t tdd_config;
 } srslte_prach_cfg_t;

lib/src/phy/phch/prach.c

@@ -52,7 +52,8 @@ int srslte_prach_set_cell_(srslte_prach_t*      p,
                            uint32_t             root_seq_index,
                            bool                 high_speed_flag,
                            uint32_t             zero_corr_zone_config,
-                           srslte_tdd_config_t* tdd_config);
+                           srslte_tdd_config_t* tdd_config,
+                           uint32_t             num_ra_preambles);
 
 uint32_t srslte_prach_get_preamble_format(uint32_t config_idx)
 {
@@ -334,7 +335,8 @@ int srslte_prach_set_cfg(srslte_prach_t* p, srslte_prach_cfg_t* cfg, uint32_t no
                                 cfg->root_seq_idx,
                                 cfg->hs_flag,
                                 cfg->zero_corr_zone,
-                                &cfg->tdd_config);
+                                &cfg->tdd_config,
+                                cfg->num_ra_preambles);
 }
 
 int srslte_prach_init(srslte_prach_t* p, uint32_t max_N_ifft_ul)
@@ -402,7 +404,8 @@ int srslte_prach_set_cell_(srslte_prach_t*      p,
                            uint32_t             root_seq_index,
                            bool                 high_speed_flag,
                            uint32_t             zero_corr_zone_config,
-                           srslte_tdd_config_t* tdd_config)
+                           srslte_tdd_config_t* tdd_config,
+                           uint32_t             num_ra_preambles)
 {
   int ret = SRSLTE_ERROR;
   if (p != NULL && N_ifft_ul < 2049 && config_idx < 64 && root_seq_index < MAX_ROOTS) {
@@ -418,6 +421,7 @@ int srslte_prach_set_cell_(srslte_prach_t*      p,
     p->hs                    = high_speed_flag;
     p->zczc                  = zero_corr_zone_config;
     p->detect_factor         = PRACH_DETECT_FACTOR;
+    p->num_ra_preambles      = num_ra_preambles;
     if (tdd_config) {
       p->tdd_config = *tdd_config;
     }
@@ -463,7 +467,10 @@ int srslte_prach_set_cell_(srslte_prach_t*      p,
     // Generate our 64 sequences
     p->N_roots = 0;
     srslte_prach_gen_seqs(p);
-
+    // Ensure num_ra_preambles is valid, if not assign default value
+    if (p->num_ra_preambles < 4 || p->num_ra_preambles > 64) {
+      p->num_ra_preambles = p->N_roots;
+    }
     // Generate sequence FFTs
     for (int i = 0; i < N_SEQS; i++) {
       srslte_dft_run(&p->zc_fft, p->seqs[i], p->dft_seqs[i]);
@@ -597,7 +604,7 @@ int srslte_prach_detect_offset(srslte_prach_t* p,
 
     memcpy(p->prach_bins, &p->signal_fft[begin], p->N_zc * sizeof(cf_t));
 
-    for (int i = 0; i < p->N_roots; i++) {
+    for (int i = 0; i < p->num_ra_preambles; i++) {
       cf_t* root_spec = p->dft_seqs[p->root_seqs_idx[i]];
 
       srslte_vec_prod_conj_ccc(p->prach_bins, root_spec, p->corr_spec, p->N_zc);

lib/src/phy/phch/test/prach_test.c

@@ -36,7 +36,7 @@ uint32_t nof_prb        = 50;
 uint32_t config_idx       = 3;
 uint32_t root_seq_idx     = 0;
 uint32_t zero_corr_zone   = 15;
-
+uint32_t num_ra_preambles = 0; // use default
 void usage(char* prog)
 {
   printf("Usage: %s\n", prog);
@@ -87,6 +87,7 @@ int main(int argc, char** argv)
   prach_cfg.freq_offset      = 0;
   prach_cfg.root_seq_idx     = root_seq_idx;
   prach_cfg.zero_corr_zone   = zero_corr_zone;
+  prach_cfg.num_ra_preambles = num_ra_preambles;
 
   if (srslte_prach_init(&prach, srslte_symbol_sz(nof_prb))) {
     return -1;

lib/src/phy/phch/test/prach_test_multi.c

@@ -37,6 +37,7 @@ uint32_t preamble_format = 0;
 uint32_t root_seq_idx     = 0;
 uint32_t zero_corr_zone   = 1;
 uint32_t n_seqs           = 64;
+uint32_t num_ra_preambles = 0; // use default
 
 void usage(char* prog)
 {
@@ -94,6 +95,7 @@ int main(int argc, char** argv)
   prach_cfg.freq_offset      = 0;
   prach_cfg.root_seq_idx     = root_seq_idx;
   prach_cfg.zero_corr_zone   = zero_corr_zone;
+  prach_cfg.num_ra_preambles = num_ra_preambles;
 
   if (srslte_prach_init(&prach, srslte_symbol_sz(nof_prb))) {
     return -1;

lib/src/phy/phch/test/prach_test_usrp.c

@@ -40,6 +40,7 @@ uint32_t frequency_offset = 0;
 uint32_t zero_corr_zone   = 11;
 float    timeadv          = 0;
 uint32_t nof_frames       = 20;
+uint32_t num_ra_preambles = 0; // use default
 
 float uhd_rx_gain = 40, uhd_tx_gain = 60, uhd_freq = 2.4e9;
 char* uhd_args        = "";
@@ -135,6 +136,7 @@ int main(int argc, char** argv)
   prach_cfg.freq_offset      = 0;
   prach_cfg.root_seq_idx     = root_seq_idx;
   prach_cfg.zero_corr_zone   = zero_corr_zone;
+  prach_cfg.num_ra_preambles = num_ra_preambles;
 
   if (srslte_prach_init(&prach, srslte_symbol_sz(nof_prb))) {
     return -1;

srsenb/hdr/phy/phy_interfaces.h

@@ -37,6 +37,7 @@ struct phy_cell_cfg_t {
   double        dl_freq_hz;
   double        ul_freq_hz;
   uint32_t      root_seq_idx;
+  uint32_t      num_ra_preambles;
 };
 
 typedef std::vector<phy_cell_cfg_t> phy_cell_cfg_list_t;

srsenb/src/enb_cfg_parser.cc

@@ -916,6 +916,8 @@ int set_derived_args(all_args_t* args_, rrc_cfg_t* rrc_cfg_, phy_cfg_t* phy_cfg_
     phy_cell_cfg.cell_id        = cfg.cell_id;
     phy_cell_cfg.root_seq_idx   = cfg.root_seq_idx;
     phy_cell_cfg.rf_port        = cfg.rf_port;
+    phy_cell_cfg.num_ra_preambles =
+        rrc_cfg_->sibs[1].sib2().rr_cfg_common.rach_cfg_common.preamb_info.nof_ra_preambs.to_number();
 
     if (cfg.dl_freq_hz > 0) {
       phy_cell_cfg.dl_freq_hz = cfg.dl_freq_hz;

srsenb/src/phy/phy.cc

@@ -67,7 +67,7 @@ void phy::parse_common_config(const phy_cfg_t& cfg)
   prach_cfg.root_seq_idx     = cfg.prach_cnfg.root_seq_idx;
   prach_cfg.zero_corr_zone   = cfg.prach_cnfg.prach_cfg_info.zero_correlation_zone_cfg;
   prach_cfg.freq_offset      = cfg.prach_cnfg.prach_cfg_info.prach_freq_offset;
-
+  prach_cfg.num_ra_preambles = cfg.phy_cell_cfg.at(0).num_ra_preambles;
   // DMRS
   workers_common.dmrs_pusch_cfg.cyclic_shift        = cfg.pusch_cnfg.ul_ref_sigs_pusch.cyclic_shift;
   workers_common.dmrs_pusch_cfg.delta_ss            = cfg.pusch_cnfg.ul_ref_sigs_pusch.group_assign_pusch;