maki/openairinterface5g
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

fixing "making SFN dependent on GPS time"

Browse Source 
in fact it syncs the USRP time to GPS time when available and then derives the SFN from the USRP time.
This commit is contained in:
Florian Kaltenberger
2022-12-27 11:49:47 +01:00
committed by Florian Kaltenberger
parent 1a0c0cd1c9
commit 00c36d7b40
1 changed files with 14 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files
executables/nr-ru.c
+14 -4
View File
@@ -622,6 +622,7 @@ void *emulatedRF_thread(void *param) {
void rx_rf(RU_t *ru,int *frame,int *slot) {
RU_proc_t *proc = &ru->proc;
NR_DL_FRAME_PARMS *fp = ru->nr_frame_parms;
openair0_config_t *cfg = &ru->openair0_cfg;
void *rxp[ru->nb_rx];
unsigned int rxs;
int i;
@@ -659,8 +660,8 @@ void rx_rf(RU_t *ru,int *frame,int *slot) {
if (rxs != samples_per_slot) LOG_E(PHY, "rx_rf: Asked for %d samples, got %d from USRP\n",samples_per_slot,rxs);
if (proc->first_rx == 1) {
ru->ts_offset = proc->timestamp_rx;
proc->timestamp_rx = 0;
//ru->ts_offset = proc->timestamp_rx;
//proc->timestamp_rx = 0;
} else {
samples_per_slot_prev = fp->get_samples_per_slot((*slot-1)%fp->slots_per_frame,fp);
@@ -671,13 +672,22 @@ void rx_rf(RU_t *ru,int *frame,int *slot) {
}
}
//compute system frame number (SFN) according to O-RAN-WG4-CUS.0-v02.00 (using alpha=beta=0)
// this assumes that the USRP has been synchronized to the GPS time
// OAI uses timestamps in sample time stored in int64_t, but it will fit in double precision for many years to come.
double gps_sec = ((double) ts)/cfg->sample_rate;
//proc->frame_rx = ((int64_t) (gps_sec/0.01)) & 1023;
// in fact the following line is the same as long as the timestamp_rx is synchronized to GPS.
proc->frame_rx = (proc->timestamp_rx / (fp->samples_per_subframe*10))&1023;
proc->tti_rx = fp->get_slot_from_timestamp(proc->timestamp_rx,fp);
// synchronize first reception to frame 0 subframe 0
LOG_D(PHY,"RU %d/%d TS %llu , frame %d, slot %d.%d / %d\n",
LOG_D(PHY,"RU %d/%d TS %ld, GPS %f, SR %f, frame %d, slot %d.%d / %d\n",
ru->idx,
0,
(unsigned long long int)(proc->timestamp_rx+ru->ts_offset),
ts, //(unsigned long long int)(proc->timestamp_rx+ru->ts_offset),
gps_sec,
cfg->sample_rate,
proc->frame_rx,proc->tti_rx,proc->tti_tx,fp->slots_per_frame);
// dump VCD output for first RU in list