Merge remote-tracking branch 'origin/define_c' into integration_2026_w03 (!3826)

Define speed of light

Common definition for speed of light constant, instead of multiple local
definitions

common/platform_constants.h

@@ -100,4 +100,5 @@
 // SDAP
 #define MAX_QOS_FLOWS 64
 
+#define SPEED_OF_LIGHT 299792458 // in m/s
 #endif /* __PLATFORM_CONSTANTS_H__ */

openair1/PHY/NR_UE_TRANSPORT/nr_ntn_l1.c

@@ -48,8 +48,6 @@ void fix_ntn_epoch_hfn(PHY_VARS_NR_UE *UE, int hfn, int frame)
   LOG_I(PHY, "setting epoch_hfn = %d\n", *epoch_hfn);
 }
 
-#define SPEED_OF_LIGHT 299792458
-
 // calculate TA and Doppler based on the NTN-Config, if abs_subframe_tx < 0 then apply only Doppler
 void apply_ntn_timing_advance_and_doppler(PHY_VARS_NR_UE *UE, const NR_DL_FRAME_PARMS *fp, int abs_subframe_tx)
 {

openair1/SIMULATION/TOOLS/random_channel.c

@@ -462,8 +462,7 @@ void get_cexp_doppler(struct complexd *cexp_doppler, channel_desc_t *chan_desc,
   // TS 38.104 - Table G.3-1
   uint16_t Dmin = 2;
   uint16_t Ds = 300;
-  double c = 299792458;
-  double v = chan_desc->max_Doppler * (c / (double)chan_desc->center_freq);
+  double v = chan_desc->max_Doppler * ((double) SPEED_OF_LIGHT / (double)chan_desc->center_freq);
 
 #ifdef DOPPLER_DEBUG
   printf("v = %f\n", v);

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_RA.c

@@ -1542,8 +1542,7 @@ static void nr_generate_Msg2(module_id_t module_idP,
   float T_c_ns = 0.509;
   int numerology = ul_bwp->scs;
   float rtt_ns = T_c_ns * 16 * 64 / (1 << numerology) * ra->timing_offset;
-  float speed_of_light_in_meters_per_second = 299792458.0f;
-  float distance_in_meters = speed_of_light_in_meters_per_second * rtt_ns / 1000 / 1000 / 1000 / 2;
+  float distance_in_meters = (float) SPEED_OF_LIGHT * rtt_ns / 1000 / 1000 / 1000 / 2;
   LOG_A(NR_MAC,
         "UE %04x: %d.%d Generating RA-Msg2 DCI, RA RNTI 0x%x, state %d, preamble_index(RAPID) %d, "
         "timing_offset = %d (estimated distance %.1f [m])\n",

radio/rfsimulator/apply_channelmod.c

@@ -65,7 +65,7 @@ void update_channel_model(channel_desc_t *channelDesc, uint64_t TS)
     const double pos_ue_y = 0;
     const double pos_ue_z = radius_earth;
 
-    const double c = 299792458; // m/s
+    const double c = (double) SPEED_OF_LIGHT;
 
     if (channelDesc->is_uplink) {
       const double dir_ue_sat_x = pos_sat_x - pos_ue_x;

radio/rfsimulator/simulator.cpp

@@ -713,7 +713,7 @@ static int rfsimu_setdistance_cmd(char *buff, int debug, telnet_printfunc_t prnt
 
   rfsimulator_state_t *t = (rfsimulator_state_t *)arg;
   const double sample_rate = t->sample_rate;
-  const double c = 299792458; /* 3e8 */
+  const double c = (double) SPEED_OF_LIGHT;
 
   const uint64_t new_offset = (double)distance * sample_rate / c;
   const double new_distance = (double)new_offset * c / sample_rate;
@@ -749,7 +749,7 @@ static int rfsimu_getdistance_cmd(char *buff, int debug, telnet_printfunc_t prnt
 
   rfsimulator_state_t *t = (rfsimulator_state_t *)arg;
   const double sample_rate = t->sample_rate;
-  const double c = 299792458; /* 3e8 */
+  const double c = (double) SPEED_OF_LIGHT;
 
   for (int i = 0; i < MAX_FD_RFSIMU; i++) {
     buffer_t *b = &t->buf[i];