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Ensure noise power is non-zero

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Prior to this commit, noise power estimation could be zero because of a
call to clearArray() in gNB_I0_measurements(). This is problematic, as
this can lead to a noise power of 0 if all symbols in a RB are used,
which in turn leads to a spike in SNR.

To avoid this, use an intermediate array to store noise power, and only
update n0_subband_power if not all RBs are used (i.e., we can detect
noise power). Further, use an exponential moving average to smoothen
noise estimation.

Fixes: fb4235fd50 ("changes in PUCCH0 SNR measurement, testing for
    PUCCH power control")
This commit is contained in:
Robert Schmidt
2026-02-04 18:36:08 +01:00
parent 9cb79027e4
commit b533127553
1 changed files with 20 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files
openair1/PHY/NR_ESTIMATION/nr_measurements_gNB.c
+20 -16
View File
@@ -144,19 +144,8 @@ void gNB_I0_measurements(PHY_VARS_gNB *gNB, int slot, int first_symb, int num_sy
PHY_MEASUREMENTS_gNB *measurements = &gNB->measurements;
int nb_symb[275]={0};
allocCast2D(n0_subband_power,
unsigned int,
gNB->measurements.n0_subband_power,
frame_parms->nb_antennas_rx,
frame_parms->N_RB_UL,
false);
clearArray(gNB->measurements.n0_subband_power, unsigned int);
allocCast2D(n0_subband_power_dB,
unsigned int,
gNB->measurements.n0_subband_power_dB,
frame_parms->nb_antennas_rx,
frame_parms->N_RB_UL,
false);
unsigned int tmp_n0_subband[frame_parms->nb_antennas_rx][frame_parms->N_RB_UL];
memset(tmp_n0_subband, 0, sizeof(tmp_n0_subband));
// TODO modify the measurements to take into account concurrent beams
for (int s = first_symb; s < first_symb + num_symb; s++) {
@@ -176,7 +165,8 @@ void gNB_I0_measurements(PHY_VARS_gNB *gNB, int slot, int first_symb, int num_sy
} else {
signal_energy = signal_energy_nodc(ul_ch, 12);
}
n0_subband_power[aarx][rb] += signal_energy;
// noise power per antenna/RB, symbols summed up
tmp_n0_subband[aarx][rb] += signal_energy;
LOG_D(NR_PHY,"slot %d symbol %d RB %d aarx %d n0_subband_power %d\n", slot, s, rb, aarx, signal_energy);
} //antenna
}
@@ -185,14 +175,28 @@ void gNB_I0_measurements(PHY_VARS_gNB *gNB, int slot, int first_symb, int num_sy
int nb_rb=0;
int64_t n0_subband_tot=0;
int32_t n0_subband_tot_perANT[frame_parms->nb_antennas_rx];
memset(n0_subband_tot_perANT, 0, sizeof(n0_subband_tot_perANT));
allocCast2D(n0_subband_power,
unsigned int,
gNB->measurements.n0_subband_power,
frame_parms->nb_antennas_rx,
frame_parms->N_RB_UL,
false);
allocCast2D(n0_subband_power_dB,
unsigned int,
gNB->measurements.n0_subband_power_dB,
frame_parms->nb_antennas_rx,
frame_parms->N_RB_UL,
false);
for (int rb = 0 ; rb<frame_parms->N_RB_UL;rb++) {
int32_t n0_subband_tot_perPRB=0;
if (nb_symb[rb] > 0) {
for (int aarx=0;aarx<frame_parms->nb_antennas_rx;aarx++) {
n0_subband_power[aarx][rb] /= nb_symb[rb];
tmp_n0_subband[aarx][rb] /= nb_symb[rb];
// apply exponential moving average to smooth noise measurements
n0_subband_power[aarx][rb] = 0.9 * n0_subband_power[aarx][rb] + 0.1 * tmp_n0_subband[aarx][rb];
n0_subband_power_dB[aarx][rb] = dB_fixed(n0_subband_power[aarx][rb]);
n0_subband_tot_perPRB += n0_subband_power[aarx][rb];
n0_subband_tot_perANT[aarx] += n0_subband_power[aarx][rb];