NR UE: add NTN specific parameter ta-Common and use it for initial timing advance, RA_contention_resolution_timer and RA_window_cnt

The value for this parameter can be set via UE command line parameter `--ntn-ta-common` in milliseconds.

executables/nr-ue.c

@@ -149,6 +149,7 @@ void init_nr_ue_vars(PHY_VARS_NR_UE *ue,
   ue->if_inst     = nr_ue_if_module_init(UE_id);
   ue->dci_thres   = 0;
   ue->target_Nid_cell = -1;
+  ue->timing_advance = ue->frame_parms.samples_per_subframe * get_nrUE_params()->ntn_ta_common;
 
   // initialize all signal buffers
   init_nr_ue_signal(ue, nb_connected_gNB);

executables/nr-uesoftmodem.h

@@ -13,6 +13,7 @@
 #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"
+#define  CONFIG_HLP_NTN_TA_COMMON          "NTN ta-Common, but given in ms\n"
 
 /***************************************************************************************************************************************/
 /* command line options definitions, CMDLINE_XXXX_DESC macros are used to initialize paramdef_t arrays which are then used as argument
@@ -66,6 +67,7 @@
   {"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}, \
   {"ntn-koffset",                  CONFIG_HLP_NTN_KOFFSET,     0,               .uptr=&(nrUE_params.ntn_koffset),            .defuintval=0,     TYPE_UINT,     0}, \
+  {"ntn-ta-common",                CONFIG_HLP_NTN_TA_COMMON,   0,               .dblptr=&(nrUE_params.ntn_ta_common),        .defdblval=0.0,    TYPE_DOUBLE,   0}, \
 }
 // clang-format on
 
@@ -87,6 +89,7 @@ typedef struct {
   int            ssb_start_subcarrier;
   int ldpc_offload_flag;
   unsigned int   ntn_koffset;
+  double         ntn_ta_common;
 } nrUE_params_t;
 extern uint64_t get_nrUE_optmask(void);
 extern uint64_t set_nrUE_optmask(uint64_t bitmask);