From 8cf8a44e8e01cfde9ae3e46df93b49390dbfbbfb Mon Sep 17 00:00:00 2001
From: Guido Casati <hello@guidocasati.com>
Date: Thu, 25 Apr 2024 22:49:56 +0200
Subject: [PATCH] Handle division by 0 assert gracefully in average channel
level calculation
* nb_re_pdsch is directly linked to nb_rb_pdsch, if the latter is 0 the
former is also 0
* compute average channel level only when number of RE for PDSCH is not 0
the average channel level will be set to 0 otherwise
* Added a log message to handle this special case, which is consequence
of other issues in the RX chain
* with this commit, the inconsistency in the RX chain will be handled
in later in nr_ue_pdsch_procedures with a demodulation failure
other minor changes:
* Improved clarity by using NR_NB_SC_PER_RB instead of hard-coded value 12 in nb of RBs calculation
* cleaned up unused variable and outdated comments
---
.../NR_UE_TRANSPORT/nr_dlsch_demodulation.c | 41 ++++++++++---------
1 file changed, 22 insertions(+), 19 deletions(-)
diff --git a/openair1/PHY/NR_UE_TRANSPORT/nr_dlsch_demodulation.c b/openair1/PHY/NR_UE_TRANSPORT/nr_dlsch_demodulation.c
index 67527b295fa..671764db170 100644
--- a/openair1/PHY/NR_UE_TRANSPORT/nr_dlsch_demodulation.c
+++ b/openair1/PHY/NR_UE_TRANSPORT/nr_dlsch_demodulation.c
@@ -213,12 +213,10 @@ static void nr_dlsch_channel_compensation(uint32_t rx_size_symbol,
*/
static void nr_dlsch_channel_level(uint32_t rx_size_symbol,
int32_t dl_ch_estimates_ext[][rx_size_symbol],
- NR_DL_FRAME_PARMS *frame_parms,
+ uint8_t n_rx,
uint8_t n_tx,
int32_t avg[MAX_ANT][MAX_ANT],
- uint8_t symbol,
- uint32_t len,
- unsigned short nb_rb);
+ uint32_t len);
void nr_dlsch_scale_channel(uint32_t rx_size_symbol,
int32_t dl_ch_estimates_ext[][rx_size_symbol],
@@ -441,8 +439,11 @@ int nr_rx_pdsch(PHY_VARS_NR_UE *ue,
if (meas_enabled)
start_meas(&meas);
if (first_symbol_flag) {
- int32_t avg[MAX_ANT][MAX_ANT];
- nr_dlsch_channel_level(rx_size_symbol, dl_ch_estimates_ext, frame_parms, nl, avg, symbol, nb_re_pdsch, nb_rb_pdsch);
+ int32_t avg[MAX_ANT][MAX_ANT] = {};
+ if (nb_re_pdsch)
+ nr_dlsch_channel_level(rx_size_symbol, dl_ch_estimates_ext, frame_parms->nb_antennas_rx, nl, avg, nb_re_pdsch);
+ else
+ LOG_E(NR_PHY, "Average channel level is 0: nb_rb_pdsch = %d, nb_re_pdsch = %d\n", nb_rb_pdsch, nb_re_pdsch);
int avgs = 0;
int32_t median[MAX_ANT][MAX_ANT];
for (int aatx = 0; aatx < nl; aatx++)
@@ -1001,33 +1002,35 @@ void nr_dlsch_scale_channel(uint32_t rx_size_symbol,
}
-//compute average channel_level on each (TX,RX) antenna pair
+/** @brief This function computes the average channel level over all allocated RBs
+ * and antennas (TX/RX) in order to compute output shift for compensated signal
+ @param rx_size_symbol
+ @param dl_ch_estimates_ext Channel estimates in allocated RBs
+ @param n_rx number of antennas in RX
+ @param n_tx number of antennas in TX
+ @param avg Pointer to average signal strength
+ @param len Number of allocated PDSCH REs
+*/
void nr_dlsch_channel_level(uint32_t rx_size_symbol,
int32_t dl_ch_estimates_ext[][rx_size_symbol],
- NR_DL_FRAME_PARMS *frame_parms,
+ uint8_t n_rx,
uint8_t n_tx,
int32_t avg[MAX_ANT][MAX_ANT],
- uint8_t symbol,
- uint32_t len,
- unsigned short nb_rb)
+ uint32_t len)
{
simde__m128i *dl_ch128, avg128D;
-
//nb_rb*nre = y * 2^x
int16_t x = factor2(len);
- //x = (x>4) ? 4 : x;
int16_t y = (len)>>x;
- //printf("len = %d = %d * 2^(%d)\n",len,y,x);
- uint32_t nb_rb_0 = len/12 + ((len%12)?1:0);
-
- AssertFatal(y!=0,"Cannot divide by zero: in function %s of file %s\n", __func__, __FILE__);
+ LOG_D(NR_PHY, "%s: %d = %d * 2^(%d)\n", __func__, len, y, x);
+ uint32_t nb_rb_0 = len / NR_NB_SC_PER_RB + ((len % NR_NB_SC_PER_RB) ? 1 : 0);
for (int aatx = 0; aatx < n_tx; aatx++) {
- for (int aarx = 0; aarx < frame_parms->nb_antennas_rx; aarx++) {
+ for (int aarx = 0; aarx < n_rx; aarx++) {
//clear average level
avg128D = simde_mm_setzero_si128();
- dl_ch128 = (simde__m128i *)dl_ch_estimates_ext[(aatx * frame_parms->nb_antennas_rx) + aarx];
+ dl_ch128 = (simde__m128i *)dl_ch_estimates_ext[(aatx * n_rx) + aarx];
for (int rb = 0; rb < nb_rb_0; rb++) {
avg128D = simde_mm_add_epi32(avg128D,simde_mm_srai_epi32(simde_mm_madd_epi16(dl_ch128[0],dl_ch128[0]),x));
--
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