NR UE: add NTN specific parameter cellSpecificKoffset_r17 and use it for UL scheduling

According to the RRC specification, cellSpecificKoffset is:
Scheduling offset used for the timing relationships that are modified for NTN (see TS 38.213 [13]).
The unit of the field K_offset is number of slots for a given subcarrier spacing of 15 kHz.
If the field is absent UE assumes value 0

This parameter `cellSpecificKoffset_r17` can be set via UE command line parameter `--ntn-koffset`.

executables/nr-uesoftmodem.h

@@ -12,6 +12,7 @@
 #define  CONFIG_HLP_DLSCH_PARA             "number of threads for dlsch processing 0 for no parallelization\n"
 #define  CONFIG_HLP_OFFSET_DIV             "Divisor for computing OFDM symbol offset in Rx chain (num samples in CP/<the value>). Default value is 8. To set the sample offset to 0, set this value ~ 10e6\n"
 #define  CONFIG_HLP_MAX_LDPC_ITERATIONS    "Maximum LDPC decoder iterations\n"
+#define  CONFIG_HLP_NTN_KOFFSET            "NTN cellSpecificKoffset-r17 (number of slots for a given subcarrier spacing of 15 kHz)\n"
 
 /***************************************************************************************************************************************/
 /* command line options definitions, CMDLINE_XXXX_DESC macros are used to initialize paramdef_t arrays which are then used as argument
@@ -63,7 +64,8 @@
   {"chest-time",                   CONFIG_HLP_CHESTTIME,       0,               .iptr=&(nrUE_params.chest_time),             .defintval=0,      TYPE_INT,      0}, \
   {"ue-timing-correction-disable", CONFIG_HLP_DISABLETIMECORR, PARAMFLAG_BOOL,  .iptr=&(nrUE_params.no_timing_correction),   .defintval=0,      TYPE_INT,      0}, \
   {"SLC",                          CONFIG_HLP_SLF,             0,               .u64ptr=&(sidelink_frequency[0][0]),         .defuintval=2600000000,TYPE_UINT64,0}, \
-  {"num-ues",                      NULL,                       0,               .iptr=&(NB_UE_INST),                         .defuintval=1,         TYPE_INT,0},   \
+  {"num-ues",                      NULL,                       0,               .iptr=&(NB_UE_INST),                         .defuintval=1,     TYPE_INT,      0}, \
+  {"ntn-koffset",                  CONFIG_HLP_NTN_KOFFSET,     0,               .uptr=&(nrUE_params.ntn_koffset),            .defuintval=0,     TYPE_UINT,     0}, \
 }
 // clang-format on
 
@@ -84,6 +86,7 @@ typedef struct {
   int            N_RB_DL;
   int            ssb_start_subcarrier;
   int ldpc_offload_flag;
+  unsigned int   ntn_koffset;
 } nrUE_params_t;
 extern uint64_t get_nrUE_optmask(void);
 extern uint64_t set_nrUE_optmask(uint64_t bitmask);

openair2/LAYER2/NR_MAC_COMMON/nr_mac.h

@@ -597,6 +597,7 @@ typedef struct {
   int n_ul_bwp;
   int dl_bw_tbslbrm;
   int ul_bw_tbslbrm;
+  NR_NTN_Config_r17_t *ntn_Config_r17;
 } NR_UE_ServingCell_Info_t;
 
 typedef enum {

openair2/LAYER2/NR_MAC_UE/config_ue.c

@@ -409,6 +409,13 @@ static void config_common_ue(NR_UE_MAC_INST_t *mac,
       // prach_fd_occasion->num_unused_root_sequences = ???
     }
   }
+
+  // NTN Config
+  if (scc->ext2) {
+    UPDATE_IE(mac->sc_info.ntn_Config_r17, scc->ext2->ntn_Config_r17, NR_NTN_Config_r17_t);
+  } else {
+    asn1cFreeStruc(asn_DEF_NR_NTN_Config_r17, mac->sc_info.ntn_Config_r17);
+  }
 }
 
 void release_common_ss_cset(NR_BWP_PDCCH_t *pdcch)
@@ -1585,6 +1592,17 @@ void nr_rrc_mac_config_req_sib1(module_id_t module_id,
   mac->phy_config_request_sent = true;
 }
 
+void nr_rrc_mac_config_req_sib19_r17(module_id_t module_id,
+                                     NR_SIB19_r17_t *sib19_r17)
+{
+  NR_UE_MAC_INST_t *mac = get_mac_inst(module_id);
+
+  // ntn-Config-r17
+  UPDATE_IE(mac->sc_info.ntn_Config_r17, sib19_r17->ntn_Config_r17, NR_NTN_Config_r17_t);
+
+  // TODO handle other SIB19 elements
+}
+
 static void handle_reconfiguration_with_sync(NR_UE_MAC_INST_t *mac,
                                              int cc_idP,
                                              const NR_ReconfigurationWithSync_t *reconfigurationWithSync)

openair2/LAYER2/NR_MAC_UE/mac_proto.h

@@ -90,6 +90,9 @@ void nr_rrc_mac_config_req_sib1(module_id_t module_id,
                                 NR_SI_SchedulingInfo_t *si_SchedulingInfo,
                                 NR_ServingCellConfigCommonSIB_t *scc);
 
+void nr_rrc_mac_config_req_sib19_r17(module_id_t module_id,
+                                     NR_SIB19_r17_t *sib19_r17);
+
 void nr_rrc_mac_config_req_reset(module_id_t module_id, NR_UE_MAC_reset_cause_t cause);
 
 /**\brief initialization NR UE MAC instance(s)*/
@@ -196,7 +199,7 @@ void set_harq_status(NR_UE_MAC_INST_t *mac,
                      uint8_t pucch_id,
                      uint8_t harq_id,
                      int8_t delta_pucch,
-                     uint8_t data_toul_fb,
+                     uint16_t data_toul_fb,
                      uint8_t dai,
                      int n_CCE,
                      int N_CCE,

openair2/LAYER2/NR_MAC_UE/main_ue_nr.c

@@ -35,7 +35,7 @@
 #include "radio/COMMON/common_lib.h"
 //#undef MALLOC
 #include "assertions.h"
-#include "executables/softmodem-common.h"
+#include "executables/nr-uesoftmodem.h"
 #include "nr_rlc/nr_rlc_oai_api.h"
 #include "RRC/NR_UE/rrc_proto.h"
 #include <pthread.h>
@@ -84,6 +84,21 @@ void nr_ue_init_mac(NR_UE_MAC_INST_t *mac)
     memset(&mac->scheduling_info.sr_info[i], 0, sizeof(mac->scheduling_info.sr_info[i]));
 
   mac->pucch_power_control_initialized = false;
+
+  // Fake SIB19 reception for NTN
+  // TODO: remove this and implement the actual SIB19 reception instead!
+  if (get_nrUE_params()->ntn_koffset) {
+    NR_SIB19_r17_t *sib19_r17 = calloc(1, sizeof(*sib19_r17));
+    sib19_r17->ntn_Config_r17 = calloc(1, sizeof(*sib19_r17->ntn_Config_r17));
+
+    // NTN cellSpecificKoffset-r17
+    if (get_nrUE_params()->ntn_koffset) {
+      asn1cCallocOne(sib19_r17->ntn_Config_r17->cellSpecificKoffset_r17, get_nrUE_params()->ntn_koffset);
+    }
+
+    nr_rrc_mac_config_req_sib19_r17(mac->ue_id, sib19_r17);
+    asn1cFreeStruc(asn_DEF_NR_SIB19_r17, sib19_r17);
+  }
 }
 
 void nr_ue_mac_default_configs(NR_UE_MAC_INST_t *mac)
@@ -246,6 +261,7 @@ void release_mac_configuration(NR_UE_MAC_INST_t *mac,
   asn1cFreeStruc(asn_DEF_NR_PUSCH_CodeBlockGroupTransmission, sc->pusch_CGB_Transmission);
   asn1cFreeStruc(asn_DEF_NR_CSI_MeasConfig, sc->csi_MeasConfig);
   asn1cFreeStruc(asn_DEF_NR_CSI_AperiodicTriggerStateList, sc->aperiodicTriggerStateList);
+  asn1cFreeStruc(asn_DEF_NR_NTN_Config_r17, sc->ntn_Config_r17);
   free(sc->xOverhead_PDSCH);
   free(sc->nrofHARQ_ProcessesForPDSCH);
   free(sc->rateMatching_PUSCH);

openair2/LAYER2/NR_MAC_UE/nr_ue_procedures.c

@@ -148,6 +148,13 @@ static nr_dci_format_t nr_extract_dci_info(NR_UE_MAC_INST_t *mac,
                                            const uint8_t *dci_pdu,
                                            const int slot);
 
+static int get_NTN_UE_Koffset(NR_NTN_Config_r17_t *ntn_Config_r17, int scs)
+{
+  if (ntn_Config_r17 && ntn_Config_r17->cellSpecificKoffset_r17)
+    return *ntn_Config_r17->cellSpecificKoffset_r17 << scs;
+  return 0;
+}
+
 int get_rnti_type(const NR_UE_MAC_INST_t *mac, const uint16_t rnti)
 {
   const RA_config_t *ra = &mac->ra;
@@ -492,7 +499,8 @@ static int nr_ue_process_dci_ul_00(NR_UE_MAC_INST_t *mac,
 
   frame_t frame_tx;
   int slot_tx;
-  if (-1 == nr_ue_pusch_scheduler(mac, 0, frame, slot, &frame_tx, &slot_tx, tda_info.k2)) {
+  const int ntn_ue_koffset = get_NTN_UE_Koffset(mac->sc_info.ntn_Config_r17, mac->current_UL_BWP->scs);
+  if (-1 == nr_ue_pusch_scheduler(mac, 0, frame, slot, &frame_tx, &slot_tx, tda_info.k2 + ntn_ue_koffset)) {
     LOG_E(MAC, "Cannot schedule PUSCH\n");
     return -1;
   }
@@ -589,7 +597,8 @@ static int nr_ue_process_dci_ul_01(NR_UE_MAC_INST_t *mac,
     tda_info.k2 = csi_K2;
   }
 
-  if (-1 == nr_ue_pusch_scheduler(mac, 0, frame, slot, &frame_tx, &slot_tx, tda_info.k2)) {
+  const int ntn_ue_koffset = get_NTN_UE_Koffset(mac->sc_info.ntn_Config_r17, mac->current_UL_BWP->scs);
+  if (-1 == nr_ue_pusch_scheduler(mac, 0, frame, slot, &frame_tx, &slot_tx, tda_info.k2 + ntn_ue_koffset)) {
     LOG_E(MAC, "Cannot schedule PUSCH\n");
     return -1;
   }
@@ -903,10 +912,15 @@ static int nr_ue_process_dci_dl_10(NR_UE_MAC_INST_t *mac,
     return -1;
   }
 
+  /* PDSCH_TO_HARQ_FEEDBACK_TIME_IND */
+  // according to TS 38.213 9.2.3
+  const int ntn_ue_koffset = get_NTN_UE_Koffset(mac->sc_info.ntn_Config_r17, dlsch_pdu->SubcarrierSpacing);
+  const uint16_t feedback_ti = 1 + dci->pdsch_to_harq_feedback_timing_indicator.val + ntn_ue_koffset;
+
   if (rnti_type != TYPE_RA_RNTI_ && rnti_type != TYPE_SI_RNTI_) {
-    AssertFatal(1 + dci->pdsch_to_harq_feedback_timing_indicator.val > DURATION_RX_TO_TX,
+    AssertFatal(feedback_ti > DURATION_RX_TO_TX,
                 "PDSCH to HARQ feedback time (%d) needs to be higher than DURATION_RX_TO_TX (%d).\n",
-                1 + dci->pdsch_to_harq_feedback_timing_indicator.val,
+                feedback_ti,
                 DURATION_RX_TO_TX);
     // set the harq status at MAC for feedback
     const int tpc[] = {-1, 0, 1, 3};
@@ -914,7 +928,7 @@ static int nr_ue_process_dci_dl_10(NR_UE_MAC_INST_t *mac,
                     dci->pucch_resource_indicator,
                     dci->harq_pid,
                     tpc[dci->tpc],
-                    1 + dci->pdsch_to_harq_feedback_timing_indicator.val,
+                    feedback_ti,
                     dci->dai[0].val,
                     dci_ind->n_CCE,
                     dci_ind->N_CCE,
@@ -948,9 +962,9 @@ static int nr_ue_process_dci_dl_10(NR_UE_MAC_INST_t *mac,
         dlsch_pdu->scaling_factor_S,
         dci->tpc,
         dci->pucch_resource_indicator,
-        1 + dci->pdsch_to_harq_feedback_timing_indicator.val);
+        feedback_ti);
 
-  dlsch_pdu->k1_feedback = 1 + dci->pdsch_to_harq_feedback_timing_indicator.val;
+  dlsch_pdu->k1_feedback = feedback_ti;
 
   LOG_D(MAC, "(nr_ue_procedures.c) pdu_type=%d\n\n", dl_conf_req->pdu_type);
 
@@ -1239,7 +1253,8 @@ static int nr_ue_process_dci_dl_11(NR_UE_MAC_INST_t *mac,
 
   /* PDSCH_TO_HARQ_FEEDBACK_TIME_IND */
   // according to TS 38.213 Table 9.2.3-1
-  uint8_t feedback_ti = pucch_Config->dl_DataToUL_ACK->list.array[dci->pdsch_to_harq_feedback_timing_indicator.val][0];
+  const int ntn_ue_koffset = get_NTN_UE_Koffset(mac->sc_info.ntn_Config_r17, dlsch_pdu->SubcarrierSpacing);
+  const uint16_t feedback_ti = pucch_Config->dl_DataToUL_ACK->list.array[dci->pdsch_to_harq_feedback_timing_indicator.val][0] + ntn_ue_koffset;
 
   AssertFatal(feedback_ti > DURATION_RX_TO_TX,
               "PDSCH to HARQ feedback time (%d) needs to be higher than DURATION_RX_TO_TX (%d). Min feedback time set in config "
@@ -1436,7 +1451,7 @@ void set_harq_status(NR_UE_MAC_INST_t *mac,
                      uint8_t pucch_id,
                      uint8_t harq_id,
                      int8_t delta_pucch,
-                     uint8_t data_toul_fb,
+                     uint16_t data_toul_fb,
                      uint8_t dai,
                      int n_CCE,
                      int N_CCE,
@@ -1457,7 +1472,7 @@ void set_harq_status(NR_UE_MAC_INST_t *mac,
   current_harq->ul_frame = frame;
   current_harq->ul_slot = slot + data_toul_fb;
   if (current_harq->ul_slot >= slots_per_frame) {
-    current_harq->ul_frame = (frame + 1) % 1024;
+    current_harq->ul_frame = (frame + current_harq->ul_slot / slots_per_frame) % MAX_FRAME_NUMBER;
     current_harq->ul_slot %= slots_per_frame;
   }
   // counter DAI in DCI ranges from 0 to 3
@@ -3544,9 +3559,13 @@ void nr_ue_process_mac_pdu(NR_UE_MAC_INST_t *mac, nr_downlink_indication_t *dl_i
         NR_UL_TIME_ALIGNMENT_t *ul_time_alignment = &mac->ul_time_alignment;
         ul_time_alignment->tag_id = tag;
         ul_time_alignment->ta_command = ta;
-        ul_time_alignment->frame = frameP;
-        ul_time_alignment->slot = slot;
         ul_time_alignment->ta_apply = adjustment_ta;
+
+        const int ntn_ue_koffset = get_NTN_UE_Koffset(mac->sc_info.ntn_Config_r17, mac->current_UL_BWP->scs);
+        const int n_slots_frame = nr_slots_per_frame[mac->current_UL_BWP->scs];
+        ul_time_alignment->frame = (frameP + (slot + ntn_ue_koffset) / n_slots_frame) % MAX_FRAME_NUMBER;
+        ul_time_alignment->slot = (slot + ntn_ue_koffset) % n_slots_frame;
+
         /*
         #ifdef DEBUG_HEADER_PARSING
         LOG_D(MAC, "[UE] CE %d : UE Timing Advance : %d\n", i, pduP[1]);
@@ -4023,9 +4042,12 @@ static void nr_ue_process_rar(NR_UE_MAC_INST_t *mac, nr_downlink_indication_t *d
       LOG_E(MAC, "Cannot schedule Msg3. Something wrong in TDA information\n");
       return;
     }
-    ret = nr_ue_pusch_scheduler(mac, is_Msg3, frame, slot, &frame_tx, &slot_tx, tda_info.k2);
-    ul_time_alignment->frame = frame_tx;
-    ul_time_alignment->slot = slot_tx;
+    const int ntn_ue_koffset = get_NTN_UE_Koffset(mac->sc_info.ntn_Config_r17, mac->current_UL_BWP->scs);
+    ret = nr_ue_pusch_scheduler(mac, is_Msg3, frame, slot, &frame_tx, &slot_tx, tda_info.k2 + ntn_ue_koffset);
+
+    const int n_slots_frame = nr_slots_per_frame[current_UL_BWP->scs];
+    ul_time_alignment->frame = (frame_tx + (slot_tx + ntn_ue_koffset) / n_slots_frame) % MAX_FRAME_NUMBER;
+    ul_time_alignment->slot = (slot_tx + ntn_ue_koffset) % n_slots_frame;
 
     if (ret != -1) {
       uint16_t rnti = mac->crnti;

openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c

@@ -1112,7 +1112,7 @@ void nr_ue_aperiodic_srs_scheduling(NR_UE_MAC_INST_t *mac, long resource_trigger
     LOG_E(NR_MAC, "Slot for scheduling aperiodic SRS %d is not an UL slot\n", sched_slot);
     return;
   }
-  int sched_frame = frame + (slot + slot_offset >= n_slots_frame) % 1024;
+  int sched_frame = frame + (slot + slot_offset / n_slots_frame) % MAX_FRAME_NUMBER;
   fapi_nr_ul_config_request_pdu_t *pdu = lockGet_ul_config(mac, sched_frame, sched_slot, FAPI_NR_UL_CONFIG_TYPE_SRS);
   if (!pdu)
     return;
@@ -1571,11 +1571,7 @@ int nr_ue_pusch_scheduler(const NR_UE_MAC_INST_t *mac,
                 DURATION_RX_TO_TX);
 
     *slot_tx = (current_slot + k2 + delta) % nr_slots_per_frame[mu];
-    if (current_slot + k2 + delta >= nr_slots_per_frame[mu]){
-      *frame_tx = (current_frame + 1) % 1024;
-    } else {
-      *frame_tx = current_frame;
-    }
+    *frame_tx = (current_frame + (current_slot + k2 + delta) / nr_slots_per_frame[mu]) % MAX_FRAME_NUMBER;
 
   } else {
 
@@ -1593,7 +1589,7 @@ int nr_ue_pusch_scheduler(const NR_UE_MAC_INST_t *mac,
 
     // Calculate TX slot and frame
     *slot_tx = (current_slot + k2) % nr_slots_per_frame[mu];
-    *frame_tx = ((current_slot + k2) > (nr_slots_per_frame[mu]-1)) ? (current_frame + 1) % 1024 : current_frame;
+    *frame_tx = (current_frame + (current_slot + k2) / nr_slots_per_frame[mu]) % MAX_FRAME_NUMBER;
 
   }