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gNB: adjust the dl_max_mcs based on the reported SSB-SINR

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This commit is contained in:
Thomas Schlichter
2025-09-09 11:17:33 +02:00
parent 2b2e9563ff
commit a9a9dfe297
3 changed files with 38 additions and 1 deletions
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openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_primitives.c
+32
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@@ -248,6 +248,38 @@ uint16_t get_pm_index(const gNB_MAC_INST *nrmac,
}
}
// look-up table for AMC. Based on BLER vs SNR curves from the nr_dlsim simulation
// command line: nr_dlsim -n 10000 -m 0 -R 25 -b 25 -e MCS -s START_SNR -t 99.99
// SNR Thresholds for MCS=[0,...,28]; START_SNR=chosen values with a resolution of 0.2dB to maintain a BLER of 10^-3
static const int SINRx10_MCS_mapping[29] = {
-10, -4, 6, 16, 24, 34, 42, 50, 56, 62, // 0..9
86, 92, 98, 104, 112, 118, 124, 140, 146, 154, // 10..19
162, 170, 178, 186, 194, 202, 212, 220, 245 // 20..28
};
int get_mcs_from_SINRx10(int mcs_table, int SINRx10, int Nl)
{
if (mcs_table != 0) {
LOG_E(MAC, "mcs_table = %d, but get_mcs_from_SINRx10() only supports MCS table 0 (TS 38.214 - Table 5.1.3.1-1)\n", mcs_table);
return 28;
}
int MIMO_SNRx10 = 0;
if (Nl == 2)
MIMO_SNRx10 = 40;
else if (Nl == 4)
MIMO_SNRx10 = 70;
for (int i = 28; i >= 0; i--) {
if (SINRx10 >= SINRx10_MCS_mapping[i] + MIMO_SNRx10)
return i;
}
LOG_W(MAC, "SINR (%d.%d dB) too low, no MCS possible to achieve BLER of 10^-3\n", SINRx10 / 10, SINRx10 % 10);
return 0;
}
uint8_t get_mcs_from_cqi(int mcs_table, int cqi_table, int cqi_idx)
{
if (cqi_idx <= 0) {
openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_uci.c
+5 -1
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@@ -539,7 +539,11 @@ static void evaluate_sinr_report(gNB_MAC_INST *nrmac,
stats->cumul_sinrx10 += sinr_report->SINRx10[0];
stats->num_sinr_meas++;
LOG_D(MAC, "Reported SSB-SINR = %d.%d\n", sinr_report->SINRx10[0] / 10, sinr_report->SINRx10[0] % 10);
const int mcs_table = UE->current_DL_BWP.mcsTableIdx;
const int nrOfLayers = get_dl_nrOfLayers(sched_ctrl, UE->current_DL_BWP.dci_format);
sched_ctrl->dl_max_mcs = get_mcs_from_SINRx10(mcs_table, sinr_report->SINRx10[0], nrOfLayers);
LOG_D(MAC, "Reported SSB-SINR = %d.%d, dl_max_mcs %d\n", sinr_report->SINRx10[0] / 10, sinr_report->SINRx10[0] % 10, sched_ctrl->dl_max_mcs);
}
static void evaluate_rsrp_report(gNB_MAC_INST *nrmac,
openair2/LAYER2/NR_MAC_gNB/mac_proto.h
+1
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@@ -403,6 +403,7 @@ uint16_t get_pm_index(const gNB_MAC_INST *nrmac,
int layers,
int xp_pdsch_antenna_ports);
int get_mcs_from_SINRx10(int mcs_table, int SINRx10, int Nl);
uint8_t get_mcs_from_cqi(int mcs_table, int cqi_table, int cqi_idx);
uint8_t get_dl_nrOfLayers(const NR_UE_sched_ctrl_t *sched_ctrl, const nr_dci_format_t dci_format);