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Dynamic PDCCH aggregation level

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The aggregation level search order for PDCCH candidates is modified:
 - the search starts from desired_agg_level_index, which is a value from 0 to 4
   proportial to pdcch_cl_adjust.
 - pdcch_cl_adjust is a value between 0 and 1 that indicates PDCCH channel quality
   by averaging HARQ DTX rate. A value of 0 means perfect channel, a value o 1 means
   impaired channel.
This commit is contained in:
Bartosz Podrygajlo
2025-02-13 10:57:14 +01:00
parent ff58b5e169
commit 16f028dba5
10 changed files with 102 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files
doc/MAC/mac-usage.md
+22
View File
@@ -38,6 +38,28 @@ The actual scheduler implementation can be found in functions `pf_dl()` and
[`gNB_scheduler_ulsch.c`](../../openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c)
(for UL), respectively.
## PDDCH aggregation level
PDCCH aggregation level is selected using closed loop controller, where DL HARQ
feedback is the controller feedback signal. It is used to increment `pdcch_cl_adjust`
variable if no feedback is detected and decrement the variable when feedback is detected.
`pdcch_cl_adjust` is later mapped PDCCH aggregation level range.
The value of `pdcch_cl_adjust` is clamped to range <0,1>, the increment value is 0.05 while
the decrement value is 0.01.
### Examples:
#### Example 1:
Say we have 90% PDCCH success rate at aggregation level 1, `pdcch_cl_adjust` will stay at 0
for most of the time. 2 consecutive PDCCH failures will not result in increasing the aggregation
level (because (0.05 + 0.05) * 4 = 0.4 which is closer to 0 than to 1). If PDCCH fails 3 times
in a row the aggregation level will change to 2 and hopefully back to 1 once more PDDCH successes
happen.
### Example 2
Say we have 0% PDCCH success rate (radio link failure scenario) but `pdcch_cl_adjust` is 0 indicating
perfect PDCCH channel. it would take ~18 PDCCH failures to reach maximum aggregation level.
# Periodic output and interpretation
The scheduler periodically outputs statistics that can help you judge the radio
openair1/PHY/NR_TRANSPORT/nr_dci.c
+3 -2
View File
@@ -99,7 +99,7 @@ static void nr_generate_dci(PHY_VARS_gNB *gNB,
if (dci_pdu->RNTI != 0xFFFF)
LOG_D(NR_PHY_DCI,
"DL_DCI : rb_offset %d, nb_rb %d, DMRS length per symbol %d\t DCI encoded length %d (precoder_granularity %d, "
"reg_mapping %d), Scrambling_Id %d, ScramblingRNTI %x, PayloadSizeBits %d\n",
"reg_mapping %d), Scrambling_Id %d, ScramblingRNTI %x, PayloadSizeBits %d AggregationLevel %d\n",
rb_offset,
n_rb,
dmrs_length,
@@ -108,7 +108,8 @@ static void nr_generate_dci(PHY_VARS_gNB *gNB,
pdcch_pdu_rel15->CceRegMappingType,
dci_pdu->ScramblingId,
dci_pdu->ScramblingRNTI,
dci_pdu->PayloadSizeBits);
dci_pdu->PayloadSizeBits,
dci_pdu->AggregationLevel);
dmrs_length += rb_offset*6; // To accommodate more DMRS symbols in case of rb offset
/// DMRS QPSK modulation
openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_RA.c
+5 -3
View File
@@ -874,7 +874,8 @@ static void nr_generate_Msg3_retransmission(module_id_t module_idP,
ss,
coreset,
&ra->sched_pdcch,
true);
true,
0);
if (CCEIndex < 0) {
LOG_E(NR_MAC, "UE %04x cannot find free CCE!\n", ra->rnti);
return;
@@ -1484,7 +1485,7 @@ static void nr_generate_Msg2(module_id_t module_idP,
}
uint8_t aggregation_level;
int CCEIndex = get_cce_index(nr_mac, CC_id, slotP, 0, &aggregation_level, beam.idx, ss, coreset, &ra->sched_pdcch, true);
int CCEIndex = get_cce_index(nr_mac, CC_id, slotP, 0, &aggregation_level, beam.idx, ss, coreset, &ra->sched_pdcch, true, 0);
if (CCEIndex < 0) {
LOG_W(NR_MAC, "UE %04x: %d.%d cannot find free CCE for Msg2!\n", ra->rnti, frameP, slotP);
@@ -2006,7 +2007,8 @@ static void nr_generate_Msg4_MsgB(module_id_t module_idP,
ss,
coreset,
&ra->sched_pdcch,
true);
true,
0);
if (CCEIndex < 0) {
LOG_E(NR_MAC, "Cannot find free CCE for RA RNTI 0x%04x!\n", ra->rnti);
openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_dlsch.c
+4 -2
View File
@@ -553,7 +553,8 @@ static bool allocate_dl_retransmission(module_id_t module_id,
sched_ctrl->search_space,
sched_ctrl->coreset,
&sched_ctrl->sched_pdcch,
false);
false,
sched_ctrl->pdcch_cl_adjust);
if (CCEIndex<0) {
LOG_D(NR_MAC, "[UE %04x][%4d.%2d] could not find free CCE for DL DCI retransmission\n", UE->rnti, frame, slot);
return false;
@@ -817,7 +818,8 @@ static void pf_dl(module_id_t module_id,
sched_ctrl->search_space,
sched_ctrl->coreset,
&sched_ctrl->sched_pdcch,
false);
false,
sched_ctrl->pdcch_cl_adjust);
if (CCEIndex < 0) {
LOG_D(NR_MAC, "[UE %04x][%4d.%2d] could not find free CCE for DL DCI\n", rnti, frame, slot);
reset_beam_status(&mac->beam_info,
openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_phytest.c
+4 -2
View File
@@ -148,7 +148,8 @@ void nr_preprocessor_phytest(module_id_t module_id, frame_t frame, sub_frame_t s
sched_ctrl->search_space,
sched_ctrl->coreset,
&sched_ctrl->sched_pdcch,
false);
false,
0);
AssertFatal(CCEIndex >= 0, "Could not find CCE for UE %04x\n", UE->rnti);
NR_sched_pdsch_t *sched_pdsch = &sched_ctrl->sched_pdsch;
@@ -312,7 +313,8 @@ bool nr_ul_preprocessor_phytest(module_id_t module_id, frame_t frame, sub_frame_
sched_ctrl->search_space,
sched_ctrl->coreset,
&sched_ctrl->sched_pdcch,
false);
false,
0);
if (CCEIndex < 0) {
LOG_E(MAC, "%s(): CCE list not empty, couldn't schedule PUSCH\n", __func__);
return false;
openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_primitives.c
+41 -6
View File
@@ -119,6 +119,9 @@ static const uint16_t cqi_table3[16][2] = {{0, 0},
{6, 6660},
{6, 7720}};
static void determine_aggregation_level_search_order(int agg_level_search_order[NUM_PDCCH_AGG_LEVELS],
float pdcch_cl_adjust);
uint8_t get_dl_nrOfLayers(const NR_UE_sched_ctrl_t *sched_ctrl,
const nr_dci_format_t dci_format) {
@@ -550,15 +553,18 @@ int get_cce_index(const gNB_MAC_INST *nrmac,
const NR_SearchSpace_t *ss,
const NR_ControlResourceSet_t *coreset,
NR_sched_pdcch_t *sched_pdcch,
bool is_common)
bool is_common,
float pdcch_cl_adjust)
{
const uint32_t Y = is_common ? 0 : get_Y(ss, slot, rnti);
uint8_t nr_of_candidates;
for (int i = 0; i < 5; i++) {
// for now taking the lowest value among the available aggregation levels
find_aggregation_candidates(aggregation_level, &nr_of_candidates, ss, 1 << i);
if(nr_of_candidates > 0)
int agg_level_search_order[NUM_PDCCH_AGG_LEVELS];
determine_aggregation_level_search_order(agg_level_search_order, pdcch_cl_adjust);
for (int i = 0; i < NUM_PDCCH_AGG_LEVELS; i++) {
find_aggregation_candidates(aggregation_level, &nr_of_candidates, ss, 1 << agg_level_search_order[i]);
if (nr_of_candidates > 0)
break;
}
int CCEIndex = find_pdcch_candidate(nrmac, CC_id, *aggregation_level, nr_of_candidates, beam_idx, sched_pdcch, coreset, Y);
@@ -2516,6 +2522,7 @@ NR_UE_info_t *add_new_nr_ue(gNB_MAC_INST *nr_mac, rnti_t rntiP, NR_CellGroupConf
sched_ctrl->ta_update = 31;
sched_ctrl->sched_srs.frame = -1;
sched_ctrl->sched_srs.slot = -1;
sched_ctrl->pdcch_cl_adjust = 0;
// initialize LCID structure
seq_arr_init(&sched_ctrl->lc_config, sizeof(nr_lc_config_t));
@@ -3524,3 +3531,31 @@ bool nr_mac_get_new_rnti(NR_UEs_t *UEs, const NR_RA_t *ra_base, int ra_count, rn
} while (loop < 100 && (exist_connected_ue || exist_in_pending_ra_ue));
return loop < 100; // nothing found: loop count 100
}
/// @brief Orders PDCCH aggregation levels so that we first check desired aggregation level according to
/// pdcch_cl_adjust
/// @param agg_level_search_order in/out 5-element array of aggregation levels from 0 to 4
/// @param pdcch_cl_adjust value from 0 to 1 indication channel impariments (0 - good channel, 1 - bad channel)
static void determine_aggregation_level_search_order(int agg_level_search_order[NUM_PDCCH_AGG_LEVELS], float pdcch_cl_adjust)
{
int desired_agg_level_index = round(4 * pdcch_cl_adjust);
int agg_level_search_index = 0;
for (int i = desired_agg_level_index; i < NUM_PDCCH_AGG_LEVELS; i++) {
agg_level_search_order[agg_level_search_index++] = i;
}
for (int i = desired_agg_level_index - 1; i >= 0; i--) {
agg_level_search_order[agg_level_search_index++] = i;
}
}
/// @brief Update PDCCH closed loop adjust for UE depending on detection of feedback.
/// @param sched_ctrl UE scheduling control info
/// @param feedback_not_detected Whether feedback (PUSCH or HARQ) was detected
void nr_mac_update_pdcch_closed_loop_adjust(NR_UE_sched_ctrl_t *sched_ctrl, bool feedback_not_detected)
{
if (feedback_not_detected) {
sched_ctrl->pdcch_cl_adjust = min(1, sched_ctrl->pdcch_cl_adjust + 0.05);
} else {
sched_ctrl->pdcch_cl_adjust = max(0, sched_ctrl->pdcch_cl_adjust - 0.01);
}
}
openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_uci.c
+1
View File
@@ -787,6 +787,7 @@ void handle_nr_uci_pucch_0_1(module_id_t mod_id,
const int8_t pid = sched_ctrl->feedback_dl_harq.head;
remove_front_nr_list(&sched_ctrl->feedback_dl_harq);
LOG_D(NR_MAC,"%4d.%2d bit %d pid %d ack/nack %d\n",frame, slot, harq_bit,pid,harq_value);
nr_mac_update_pdcch_closed_loop_adjust(sched_ctrl, harq_confidence != 0);
handle_dl_harq(UE, pid, harq_value == 0 && harq_confidence == 0, nrmac->dl_bler.harq_round_max);
if (!UE->Msg4_MsgB_ACKed && harq_value == 0 && harq_confidence == 0)
UE->Msg4_MsgB_ACKed = true;
openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c
+6 -3
View File
@@ -1742,7 +1742,8 @@ static bool allocate_ul_retransmission(gNB_MAC_INST *nrmac,
sched_ctrl->search_space,
sched_ctrl->coreset,
&sched_ctrl->sched_pdcch,
false);
false,
sched_ctrl->pdcch_cl_adjust);
if (CCEIndex<0) {
LOG_D(NR_MAC, "[UE %04x][%4d.%2d] no free CCE for retransmission UL DCI UE\n", UE->rnti, frame, slot);
return false;
@@ -1926,7 +1927,8 @@ static void pf_ul(module_id_t module_id,
sched_ctrl->search_space,
sched_ctrl->coreset,
&sched_ctrl->sched_pdcch,
false);
false,
sched_ctrl->pdcch_cl_adjust);
if (CCEIndex < 0) {
LOG_D(NR_MAC, "[UE %04x][%4d.%2d] no free CCE for UL DCI (BSR 0)\n", UE->rnti, frame, slot);
reset_beam_status(&nrmac->beam_info, sched_frame, sched_slot, UE->UE_beam_index, n, beam.new_beam);
@@ -2073,7 +2075,8 @@ static void pf_ul(module_id_t module_id,
sched_ctrl->search_space,
sched_ctrl->coreset,
&sched_ctrl->sched_pdcch,
false);
false,
sched_ctrl->pdcch_cl_adjust);
if (CCEIndex < 0) {
reset_beam_status(&nrmac->beam_info, frame, slot, iterator->UE->UE_beam_index, n_dl, dci_beam.new_beam);
openair2/LAYER2/NR_MAC_gNB/mac_proto.h
+3 -1
View File
@@ -433,7 +433,8 @@ int get_cce_index(const gNB_MAC_INST *nrmac,
const NR_SearchSpace_t *ss,
const NR_ControlResourceSet_t *coreset,
NR_sched_pdcch_t *sched_pdcch,
bool is_common);
bool is_common,
float pdcch_cl_adjust);
bool nr_find_nb_rb(uint16_t Qm,
uint16_t R,
@@ -493,5 +494,6 @@ bool nr_mac_add_lcid(NR_UE_sched_ctrl_t *sched_ctrl, const nr_lc_config_t *c);
bool nr_mac_remove_lcid(NR_UE_sched_ctrl_t *sched_ctrl, long lcid);
bool nr_mac_get_new_rnti(NR_UEs_t *UEs, const NR_RA_t *ra_base, int ra_count, rnti_t *rnti);
void nr_mac_update_pdcch_closed_loop_adjust(NR_UE_sched_ctrl_t *sched_ctrl, bool feedback_not_detected);
#endif /*__LAYER2_NR_MAC_PROTO_H__*/
openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h
+13
View File
@@ -125,6 +125,15 @@ typedef enum {
nrRA_WAIT_Msg4_MsgB_ACK,
} RA_gNB_state_t;
typedef enum {
PDCCH_AGG_LEVEL1 = 0,
PDCCH_AGG_LEVEL2,
PDCCH_AGG_LEVEL4,
PDCCH_AGG_LEVEL8,
PDCCH_AGG_LEVEL16,
NUM_PDCCH_AGG_LEVELS
} Pdcch_Aggregation_Level_t;
static const char *const nrra_text[] =
{"IDLE", "Msg2", "WAIT_MsgA_PUSCH", "WAIT_Msg3", "Msg3_retransmission", "Msg3_dcch_dtch", "Msg4", "MsgB", "WAIT_Msg4_ACK"};
@@ -675,6 +684,10 @@ typedef struct {
/// per-LC configuration
seq_arr_t lc_config;
// pdcch closed loop adjust for PDCCH aggregation level, range <0, 1>
// 0 - good channel, 1 - bad channel
float pdcch_cl_adjust;
} NR_UE_sched_ctrl_t;
typedef struct {