From ab6d7afd09b02963ba345c983acef44acfdf8322 Mon Sep 17 00:00:00 2001
From: Roberto Louro Magueta <rmagueta@allbesmart.pt>
Date: Mon, 9 May 2022 15:54:20 +0100
Subject: [PATCH] Compute the SNR per RB using the SRS
---
openair1/PHY/INIT/nr_init.c | 2 +
.../NR_ESTIMATION/nr_ul_channel_estimation.c | 37 ++++++++++++++-----
openair1/PHY/NR_ESTIMATION/nr_ul_estimation.h | 4 +-
openair1/PHY/defs_nr_common.h | 2 +
openair1/SCHED_NR/phy_procedures_nr_gNB.c | 4 +-
5 files changed, 38 insertions(+), 11 deletions(-)
diff --git a/openair1/PHY/INIT/nr_init.c b/openair1/PHY/INIT/nr_init.c
index 64bbdfa4878..21ebcc14059 100644
--- a/openair1/PHY/INIT/nr_init.c
+++ b/openair1/PHY/INIT/nr_init.c
@@ -618,8 +618,10 @@ int phy_init_nr_gNB(PHY_VARS_gNB *gNB,
gNB->nr_srs_info[id] = (nr_srs_info_t *)malloc16_clear(sizeof(nr_srs_info_t));
gNB->nr_srs_info[id]->sc_list = (uint16_t *) malloc16_clear(6*fp->N_RB_UL*sizeof(uint16_t));
gNB->nr_srs_info[id]->srs_generated_signal = (int32_t*)malloc16_clear(fp->ofdm_symbol_size*MAX_NUM_NR_SRS_SYMBOLS*sizeof(int32_t));
+ gNB->nr_srs_info[id]->signal_power = (uint32_t*)malloc16_clear(sizeof(uint32_t));
gNB->nr_srs_info[id]->noise_power_per_rb = (uint32_t*)malloc16_clear(fp->N_RB_UL*sizeof(uint32_t));
gNB->nr_srs_info[id]->noise_power = (uint32_t*)malloc16_clear(sizeof(uint32_t));
+ gNB->nr_srs_info[id]->snr_per_rb = (int8_t*)malloc16_clear(fp->N_RB_UL*sizeof(int8_t));
gNB->nr_srs_info[id]->srs_received_signal = (int32_t **)malloc16(Prx*sizeof(int32_t*));
gNB->nr_srs_info[id]->srs_ls_estimated_channel = (int32_t **)malloc16(Prx*sizeof(int32_t*));
gNB->nr_srs_info[id]->srs_estimated_channel_freq = (int32_t **)malloc16(Prx*sizeof(int32_t*));
diff --git a/openair1/PHY/NR_ESTIMATION/nr_ul_channel_estimation.c b/openair1/PHY/NR_ESTIMATION/nr_ul_channel_estimation.c
index ffdf07860dd..8db33e3e185 100644
--- a/openair1/PHY/NR_ESTIMATION/nr_ul_channel_estimation.c
+++ b/openair1/PHY/NR_ESTIMATION/nr_ul_channel_estimation.c
@@ -1079,9 +1079,9 @@ void nr_pusch_ptrs_processing(PHY_VARS_gNB *gNB,
}//Antenna loop
}
-uint32_t calc_power(uint16_t *x, uint32_t size) {
- uint64_t sum_x = 0;
- uint64_t sum_x2 = 0;
+uint32_t calc_power(const int16_t *x, uint32_t size) {
+ int64_t sum_x = 0;
+ int64_t sum_x2 = 0;
for(int k = 0; k<size; k++) {
sum_x = sum_x + x[k];
sum_x2 = sum_x2 + x[k]*x[k];
@@ -1099,8 +1099,10 @@ int nr_srs_channel_estimation(PHY_VARS_gNB *gNB,
int32_t **srs_estimated_channel_freq,
int32_t **srs_estimated_channel_time,
int32_t **srs_estimated_channel_time_shifted,
+ uint32_t *signal_power,
uint32_t *noise_power_per_rb,
- uint32_t *noise_power) {
+ uint32_t *noise_power,
+ int8_t *snr_per_rb) {
if(nr_srs_info->sc_list_length == 0) {
LOG_E(NR_PHY, "(%d.%d) nr_srs_info was not generated yet!\n", frame, slot);
@@ -1110,8 +1112,10 @@ int nr_srs_channel_estimation(PHY_VARS_gNB *gNB,
NR_DL_FRAME_PARMS *frame_parms = &gNB->frame_parms;
int32_t **srs_ls_estimated_channel = nr_srs_info->srs_ls_estimated_channel;
- uint16_t noise_real[frame_parms->nb_antennas_rx*nr_srs_info->sc_list_length];
- uint16_t noise_imag[frame_parms->nb_antennas_rx*nr_srs_info->sc_list_length];
+ int16_t ch_real[frame_parms->nb_antennas_rx*nr_srs_info->sc_list_length];
+ int16_t ch_imag[frame_parms->nb_antennas_rx*nr_srs_info->sc_list_length];
+ int16_t noise_real[frame_parms->nb_antennas_rx*nr_srs_info->sc_list_length];
+ int16_t noise_imag[frame_parms->nb_antennas_rx*nr_srs_info->sc_list_length];
int16_t ls_estimated[2];
@@ -1199,8 +1203,10 @@ int nr_srs_channel_estimation(PHY_VARS_gNB *gNB,
// Compute noise
for(int sc_idx = 0; sc_idx < nr_srs_info->sc_list_length; sc_idx++) {
- noise_real[ant*nr_srs_info->sc_list_length + sc_idx] = abs((int16_t)((srs_ls_estimated_channel[ant][nr_srs_info->sc_list[sc_idx]]-srs_estimated_channel_freq[ant][nr_srs_info->sc_list[sc_idx]]) & 0xFFFF));
- noise_imag[ant*nr_srs_info->sc_list_length + sc_idx] = abs((int16_t)(((srs_ls_estimated_channel[ant][nr_srs_info->sc_list[sc_idx]]-srs_estimated_channel_freq[ant][nr_srs_info->sc_list[sc_idx]]) >> 16) & 0xFFFF));
+ ch_real[ant*nr_srs_info->sc_list_length + sc_idx] = (int16_t)(srs_estimated_channel_freq[ant][nr_srs_info->sc_list[sc_idx]] & 0xFFFF);
+ ch_imag[ant*nr_srs_info->sc_list_length + sc_idx] = (int16_t)((srs_estimated_channel_freq[ant][nr_srs_info->sc_list[sc_idx]] >> 16) & 0xFFFF);
+ noise_real[ant*nr_srs_info->sc_list_length + sc_idx] = abs((int16_t)(srs_ls_estimated_channel[ant][nr_srs_info->sc_list[sc_idx]] & 0xFFFF) - ch_real[ant*nr_srs_info->sc_list_length + sc_idx]);
+ noise_imag[ant*nr_srs_info->sc_list_length + sc_idx] = abs((int16_t)((srs_ls_estimated_channel[ant][nr_srs_info->sc_list[sc_idx]] >> 16) & 0xFFFF) - ch_imag[ant*nr_srs_info->sc_list_length + sc_idx]);
}
// Convert to time domain
@@ -1217,8 +1223,20 @@ int nr_srs_channel_estimation(PHY_VARS_gNB *gNB,
(gNB->frame_parms.ofdm_symbol_size>>1)*sizeof(int32_t));
}
+ // Compute signal power
+ *signal_power = calc_power(ch_real,frame_parms->nb_antennas_rx*nr_srs_info->sc_list_length)
+ + calc_power(ch_imag,frame_parms->nb_antennas_rx*nr_srs_info->sc_list_length);
+
+#ifdef SRS_DEBUG
+ LOG_I(NR_PHY,"signal_power = %u\n", *signal_power);
+#endif
+
// Compute noise power
+ uint8_t signal_power_bits = log2_approx(*signal_power);
+ uint8_t factor_bits = signal_power_bits < 32 ? 32 - signal_power_bits : 0; // 32 due to input of dB_fixed(uint32_t x)
+ int32_t factor_dB = dB_fixed(1<<factor_bits);
+
uint64_t subcarrier_offset = frame_parms->first_carrier_offset + srs_pdu->bwp_start*12;
uint8_t srs_symbols_per_rb = srs_pdu->comb_size == 0 ? 6 : 3;
uint8_t n_noise_estimates = frame_parms->nb_antennas_rx*srs_symbols_per_rb;
@@ -1247,6 +1265,7 @@ int nr_srs_channel_estimation(PHY_VARS_gNB *gNB,
if (count_estimates == n_noise_estimates) {
noise_power_per_rb[rb] = sum_re2/n_noise_estimates - (sum_re/n_noise_estimates)*(sum_re/n_noise_estimates) +
sum_im2/n_noise_estimates - (sum_im/n_noise_estimates)*(sum_im/n_noise_estimates);
+ snr_per_rb[rb] = dB_fixed((int32_t)((*signal_power<<factor_bits)/noise_power_per_rb[rb])) - factor_dB;
count_estimates = 0;
sum_re = 0;
sum_re2 = 0;
@@ -1254,7 +1273,7 @@ int nr_srs_channel_estimation(PHY_VARS_gNB *gNB,
sum_im2 = 0;
#ifdef SRS_DEBUG
- LOG_I(NR_PHY,"noise_power_per_rb[%i] = %i\n", rb, noise_power_per_rb[rb]);
+ LOG_I(NR_PHY,"noise_power_per_rb[%i] = %i, snr_per_rb[%i] = %i dB\n", rb, noise_power_per_rb[rb], rb, snr_per_rb[rb]);
#endif
}
diff --git a/openair1/PHY/NR_ESTIMATION/nr_ul_estimation.h b/openair1/PHY/NR_ESTIMATION/nr_ul_estimation.h
index 9c7d67b25d6..f7ac055dcc0 100644
--- a/openair1/PHY/NR_ESTIMATION/nr_ul_estimation.h
+++ b/openair1/PHY/NR_ESTIMATION/nr_ul_estimation.h
@@ -73,6 +73,8 @@ int nr_srs_channel_estimation(PHY_VARS_gNB *gNB,
int32_t **srs_estimated_channel_freq,
int32_t **srs_estimated_channel_time,
int32_t **srs_estimated_channel_time_shifted,
+ uint32_t *signal_power,
uint32_t *noise_power_per_rb,
- uint32_t *noise_power);
+ uint32_t *noise_power,
+ int8_t *snr_per_rb);
#endif
diff --git a/openair1/PHY/defs_nr_common.h b/openair1/PHY/defs_nr_common.h
index 80842eef386..4109b138317 100644
--- a/openair1/PHY/defs_nr_common.h
+++ b/openair1/PHY/defs_nr_common.h
@@ -244,8 +244,10 @@ typedef struct {
int32_t **srs_estimated_channel_freq;
int32_t **srs_estimated_channel_time;
int32_t **srs_estimated_channel_time_shifted;
+ uint32_t *signal_power;
uint32_t *noise_power_per_rb;
uint32_t *noise_power;
+ int8_t *snr_per_rb;
} nr_srs_info_t;
typedef struct NR_DL_FRAME_PARMS NR_DL_FRAME_PARMS;
diff --git a/openair1/SCHED_NR/phy_procedures_nr_gNB.c b/openair1/SCHED_NR/phy_procedures_nr_gNB.c
index aa75cc64ef3..b342b87fa80 100644
--- a/openair1/SCHED_NR/phy_procedures_nr_gNB.c
+++ b/openair1/SCHED_NR/phy_procedures_nr_gNB.c
@@ -834,8 +834,10 @@ int phy_procedures_gNB_uespec_RX(PHY_VARS_gNB *gNB, int frame_rx, int slot_rx) {
gNB->nr_srs_info[i]->srs_estimated_channel_freq,
gNB->nr_srs_info[i]->srs_estimated_channel_time,
gNB->nr_srs_info[i]->srs_estimated_channel_time_shifted,
+ gNB->nr_srs_info[i]->signal_power,
gNB->nr_srs_info[i]->noise_power_per_rb,
- gNB->nr_srs_info[i]->noise_power);
+ gNB->nr_srs_info[i]->noise_power,
+ gNB->nr_srs_info[i]->snr_per_rb);
T(T_GNB_PHY_UL_FREQ_CHANNEL_ESTIMATE, T_INT(0), T_INT(srs_pdu->rnti), T_INT(frame_rx), T_INT(0), T_INT(0),
T_BUFFER(gNB->nr_srs_info[i]->srs_estimated_channel_freq[0], gNB->frame_parms.ofdm_symbol_size*sizeof(int32_t)));
--
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