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rfsimulator: enable and correct NTN LEO doppler simulation

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This commit is contained in:
Thomas Schlichter
2025-04-10 13:56:20 +00:00
parent 18469302d8
commit d6585f3750
4 changed files with 93 additions and 36 deletions
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radio/rfsimulator/apply_channelmod.c
+75 -35
View File
@@ -50,6 +50,8 @@ void rxAddInput(const c16_t *input_sig,
uint32_t CirSize,
bool add_noise)
{
static uint64_t last_TS = 0;
if ((channelDesc->sat_height > 0) && (channelDesc->enable_dynamic_delay || channelDesc->enable_dynamic_Doppler)) { // model for transparent satellite on circular orbit
/* assumptions:
- The Earth is spherical, the ground station is static, and that the Earth does not rotate.
@@ -82,42 +84,76 @@ void rxAddInput(const c16_t *input_sig,
const double pos_ue_y = 0;
const double pos_ue_z = radius_earth;
const double dir_sat_ue_x = pos_ue_x - pos_sat_x;
const double dir_sat_ue_y = pos_ue_y - pos_sat_y;
const double dir_sat_ue_z = pos_ue_z - pos_sat_z;
const double dist_sat_ue = sqrt(dir_sat_ue_x * dir_sat_ue_x + dir_sat_ue_y * dir_sat_ue_y + dir_sat_ue_z * dir_sat_ue_z);
const double vel_sat_ue = (vel_sat_x * dir_sat_ue_x + vel_sat_y * dir_sat_ue_y + vel_sat_z * dir_sat_ue_z) / dist_sat_ue;
double dist_gnb_sat = 0;
double vel_gnb_sat = 0;
if (channelDesc->modelid == SAT_LEO_TRANS) {
const double pos_gnb_x = 0;
const double pos_gnb_y = 0;
const double pos_gnb_z = radius_earth;
const double dir_gnb_sat_x = pos_sat_x - pos_gnb_x;
const double dir_gnb_sat_y = pos_sat_y - pos_gnb_y;
const double dir_gnb_sat_z = pos_sat_z - pos_gnb_z;
dist_gnb_sat = sqrt(dir_gnb_sat_x * dir_gnb_sat_x + dir_gnb_sat_y * dir_gnb_sat_y + dir_gnb_sat_z * dir_gnb_sat_z);
vel_gnb_sat = (vel_sat_x * dir_gnb_sat_x + vel_sat_y * dir_gnb_sat_y + vel_sat_z * dir_gnb_sat_z) / dist_gnb_sat;
}
const double c = 299792458; // m/s
const double prop_delay = (dist_gnb_sat + dist_sat_ue) / c;
if (channelDesc->enable_dynamic_delay)
channelDesc->channel_offset = prop_delay * channelDesc->sampling_rate;
const double f_Doppler_shift_sat_ue = (vel_sat_ue / (c - vel_sat_ue)) * channelDesc->center_freq;
const double f_Doppler_shift_gnb_sat = (-vel_gnb_sat / c) * channelDesc->center_freq;
if (channelDesc->enable_dynamic_Doppler)
channelDesc->Doppler_phase_inc = 2 * M_PI * (f_Doppler_shift_gnb_sat + f_Doppler_shift_sat_ue) / channelDesc->sampling_rate;
if (channelDesc->is_uplink) {
const double dir_ue_sat_x = pos_sat_x - pos_ue_x;
const double dir_ue_sat_y = pos_sat_y - pos_ue_y;
const double dir_ue_sat_z = pos_sat_z - pos_ue_z;
static uint64_t last_TS = 0;
if(TS - last_TS >= channelDesc->sampling_rate) {
last_TS = TS;
LOG_I(HW, "Satellite orbit: time %f s, Doppler: gNB->SAT %f kHz, SAT->UE %f kHz, Delay %f ms\n", t, f_Doppler_shift_gnb_sat / 1000, f_Doppler_shift_sat_ue / 1000, prop_delay * 1000);
const double dist_ue_sat = sqrt(dir_ue_sat_x * dir_ue_sat_x + dir_ue_sat_y * dir_ue_sat_y + dir_ue_sat_z * dir_ue_sat_z);
const double vel_ue_sat = (vel_sat_x * dir_ue_sat_x + vel_sat_y * dir_ue_sat_y + vel_sat_z * dir_ue_sat_z) / dist_ue_sat;
double dist_sat_gnb = 0;
if (channelDesc->modelid == SAT_LEO_TRANS) {
const double pos_gnb_x = 0;
const double pos_gnb_y = 0;
const double pos_gnb_z = radius_earth;
const double dir_sat_gnb_x = pos_gnb_x - pos_sat_x;
const double dir_sat_gnb_y = pos_gnb_y - pos_sat_y;
const double dir_sat_gnb_z = pos_gnb_z - pos_sat_z;
dist_sat_gnb = sqrt(dir_sat_gnb_x * dir_sat_gnb_x + dir_sat_gnb_y * dir_sat_gnb_y + dir_sat_gnb_z * dir_sat_gnb_z);
}
const double prop_delay = (dist_ue_sat + dist_sat_gnb) / c;
if (channelDesc->enable_dynamic_delay)
channelDesc->channel_offset = prop_delay * channelDesc->sampling_rate;
const double f_Doppler_shift_ue_sat = (-vel_ue_sat / c) * channelDesc->center_freq;
if (channelDesc->enable_dynamic_Doppler)
channelDesc->Doppler_phase_inc = 2 * M_PI * f_Doppler_shift_ue_sat / channelDesc->sampling_rate;
if(TS - last_TS >= channelDesc->sampling_rate) {
last_TS = TS;
LOG_D(HW, "Satellite orbit: time %f s, Position = (%f, %f, %f), Velocity = (%f, %f, %f)\n", t, pos_sat_x, pos_sat_y, pos_sat_z, vel_sat_x, vel_sat_y, vel_sat_z);
LOG_D(HW, "Uplink delay %f ms, Doppler shift UE->SAT %f kHz\n", prop_delay * 1000, f_Doppler_shift_ue_sat / 1000);
}
} else {
const double dir_sat_ue_x = pos_ue_x - pos_sat_x;
const double dir_sat_ue_y = pos_ue_y - pos_sat_y;
const double dir_sat_ue_z = pos_ue_z - pos_sat_z;
const double dist_sat_ue = sqrt(dir_sat_ue_x * dir_sat_ue_x + dir_sat_ue_y * dir_sat_ue_y + dir_sat_ue_z * dir_sat_ue_z);
const double vel_sat_ue = (vel_sat_x * dir_sat_ue_x + vel_sat_y * dir_sat_ue_y + vel_sat_z * dir_sat_ue_z) / dist_sat_ue;
double dist_gnb_sat = 0;
if (channelDesc->modelid == SAT_LEO_TRANS) {
const double pos_gnb_x = 0;
const double pos_gnb_y = 0;
const double pos_gnb_z = radius_earth;
const double dir_gnb_sat_x = pos_sat_x - pos_gnb_x;
const double dir_gnb_sat_y = pos_sat_y - pos_gnb_y;
const double dir_gnb_sat_z = pos_sat_z - pos_gnb_z;
dist_gnb_sat = sqrt(dir_gnb_sat_x * dir_gnb_sat_x + dir_gnb_sat_y * dir_gnb_sat_y + dir_gnb_sat_z * dir_gnb_sat_z);
}
const double prop_delay = (dist_gnb_sat + dist_sat_ue) / c;
if (channelDesc->enable_dynamic_delay)
channelDesc->channel_offset = prop_delay * channelDesc->sampling_rate;
const double f_Doppler_shift_sat_ue = (vel_sat_ue / (c - vel_sat_ue)) * channelDesc->center_freq;
if (channelDesc->enable_dynamic_Doppler)
channelDesc->Doppler_phase_inc = 2 * M_PI * f_Doppler_shift_sat_ue / channelDesc->sampling_rate;
if(TS - last_TS >= channelDesc->sampling_rate) {
last_TS = TS;
LOG_D(HW, "Satellite orbit: time %f s, Position = (%f, %f, %f), Velocity = (%f, %f, %f)\n", t, pos_sat_x, pos_sat_y, pos_sat_z, vel_sat_x, vel_sat_y, vel_sat_z);
LOG_D(HW, "Downlink delay %f ms, Doppler shift SAT->UE %f kHz\n", prop_delay * 1000, f_Doppler_shift_sat_ue / 1000);
}
}
}
@@ -131,6 +167,8 @@ void rxAddInput(const c16_t *input_sig,
const double noise_per_sample = add_noise ? pow(10,channelDesc->noise_power_dB/10.0) * 256 : 0;
const uint64_t dd = channelDesc->channel_offset;
const int nbTx=channelDesc->nb_tx;
double Doppler_phase_cur = channelDesc->Doppler_phase_cur[rxAnt];
Doppler_phase_cur -= 2 * M_PI * round(Doppler_phase_cur / (2 * M_PI));
for (int i=0; i<nbSamples; i++) {
cf_t *out_ptr = after_channel_sig + i;
@@ -161,10 +199,10 @@ void rxAddInput(const c16_t *input_sig,
#else
double complex in = rx_tmp.r + rx_tmp.i * I;
#endif
double complex out = in * cexp(channelDesc->Doppler_phase_cur[rxAnt] * I);
double complex out = in * cexp(Doppler_phase_cur * I);
rx_tmp.r = creal(out);
rx_tmp.i = cimag(out);
channelDesc->Doppler_phase_cur[rxAnt] += channelDesc->Doppler_phase_inc;
Doppler_phase_cur += channelDesc->Doppler_phase_inc;
}
out_ptr->r += rx_tmp.r * pathLossLinear + noise_per_sample * gaussZiggurat(0.0, 1.0);
@@ -172,6 +210,8 @@ void rxAddInput(const c16_t *input_sig,
out_ptr++;
}
channelDesc->Doppler_phase_cur[rxAnt] = Doppler_phase_cur;
if ( (TS*nbTx)%CirSize+nbSamples <= CirSize )
// Cast to a wrong type for compatibility !
LOG_D(HW,"Input power %f, output power: %f, channel path loss %f, noise coeff: %f \n",
radio/rfsimulator/simulator.c
+2
View File
@@ -274,6 +274,7 @@ static int allocCirBuf(rfsimulator_state_t *bridge, int sock)
}
set_channeldesc_owner(ptr->channel_model, RFSIMU_MODULEID);
set_channeldesc_direction(ptr->channel_model, bridge->role == SIMU_ROLE_SERVER);
random_channel(ptr->channel_model,false);
LOG_I(HW, "Random channel %s in rfsimulator activated\n", modelname);
}
@@ -467,6 +468,7 @@ static int rfsimu_setchanmod_cmd(char *buff, int debug, telnet_printfunc_t prnt,
t->chan_pathloss,
0); // noise_power
set_channeldesc_owner(newmodel, RFSIMU_MODULEID);
set_channeldesc_direction(newmodel, t->role == SIMU_ROLE_SERVER);
set_channeldesc_name(newmodel,modelname);
random_channel(newmodel,false);
channel_desc_t *oldmodel=b->channel_model;