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Procedures for Contention Resolution

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This commit is contained in:
francescomani
2025-03-12 10:21:27 +01:00
parent cc154da549
commit e958822a73
4 changed files with 40 additions and 79 deletions
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openair2/LAYER2/NR_MAC_UE/mac_proto.h
+2 -5
View File
@@ -300,12 +300,9 @@ void configure_csi_resource_mapping(fapi_nr_dl_config_csirs_pdu_rel15_t *csirs_c
*/
void nr_ue_msg3_scheduler(NR_UE_MAC_INST_t *mac, frame_t current_frame, slot_t current_slot, uint8_t Msg3_tda_id);
void nr_ue_contention_resolution(NR_UE_MAC_INST_t *mac, int cc_id, frame_t frame, int slot, NR_PRACH_RESOURCES_t *prach_resources);
void nr_ra_failed(NR_UE_MAC_INST_t *mac, uint8_t CC_id, NR_PRACH_RESOURCES_t *prach_resources, frame_t frame, int slot);
void nr_ra_contention_resolution_failed(RA_config_t *ra);
void nr_ra_succeeded(NR_UE_MAC_INST_t *mac, const uint8_t gNB_index, const frame_t frame, const int slot);
void nr_ra_backoff_setting(RA_config_t *ra);
void nr_get_RA_window(NR_UE_MAC_INST_t *mac);
/*@mac pointer to MAC instance
openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c
+28 -65
View File
@@ -1174,8 +1174,6 @@ void nr_get_Msg3_MsgA_PUSCH_payload(NR_UE_MAC_INST_t *mac, uint8_t *buf, int TBS
void nr_ue_manage_ra_procedure(NR_UE_MAC_INST_t *mac, int CC_id, frame_t frame, uint8_t gNB_id, int nr_slot_tx)
{
RA_config_t *ra = &mac->ra;
NR_PRACH_RESOURCES_t *prach_resources = &ra->prach_resources;
if (ra->ra_state == nrRA_UE_IDLE) {
bool init_success = init_RA(mac, frame);
if (!init_success)
@@ -1199,30 +1197,6 @@ void nr_ue_manage_ra_procedure(NR_UE_MAC_INST_t *mac, int CC_id, frame_t frame,
ra_resource_selection(mac);
}
}
if (nr_timer_is_active(&ra->contention_resolution_timer)) {
nr_ue_contention_resolution(mac, CC_id, frame, nr_slot_tx, prach_resources);
}
}
////////////////////////////////////////////////////////////////////////////
/////////* Random Access Contention Resolution (5.1.35 TS 38.321) */////////
////////////////////////////////////////////////////////////////////////////
// Handling contention resolution timer
// WIP todo:
// - beam failure recovery
// - RA completed
void nr_ue_contention_resolution(NR_UE_MAC_INST_t *mac, int cc_id, frame_t frame, int slot, NR_PRACH_RESOURCES_t *prach_resources)
{
RA_config_t *ra = &mac->ra;
if (nr_timer_expired(&ra->contention_resolution_timer)) {
ra->t_crnti = 0;
nr_timer_stop(&ra->contention_resolution_timer);
// Signal PHY to quit RA procedure
LOG_E(MAC, "[UE %d] 4-Step CBRA: Contention resolution timer has expired, RA procedure has failed...\n", mac->ue_id);
nr_ra_failed(mac, cc_id, prach_resources, frame, slot);
}
}
// Handlig successful RA completion @ MAC layer
@@ -1250,7 +1224,6 @@ void nr_ra_succeeded(NR_UE_MAC_INST_t *mac, const uint8_t gNB_index, const frame
mac->ue_id,
frame,
slot);
nr_timer_stop(&ra->contention_resolution_timer);
mac->crnti = ra->t_crnti;
ra->t_crnti = 0;
LOG_D(MAC, "[UE %d][%d.%d] CBRA: cleared contention resolution timer...\n", mac->ue_id, frame, slot);
@@ -1264,6 +1237,33 @@ void nr_ra_succeeded(NR_UE_MAC_INST_t *mac, const uint8_t gNB_index, const frame
nr_mac_rrc_ra_ind(mac->ue_id, frame, true);
}
void nr_ra_backoff_setting(RA_config_t *ra)
{
// select a random backoff time according to a uniform distribution
// between 0 and the PREAMBLE_BACKOFF
uint32_t seed = (unsigned int)(rdtsc_oai() & ~0);
uint32_t random_backoff = ra->RA_backoff_limit ? rand_r(&seed) % ra->RA_backoff_limit : 0; // in slots
nr_timer_setup(&ra->RA_backoff_timer, random_backoff, 1);
nr_timer_start(&ra->RA_backoff_timer);
}
void nr_ra_contention_resolution_failed(RA_config_t *ra)
{
// discard the TEMPORARY_C-RNTI
ra->t_crnti = 0;
// flush MSG3 buffer
free_and_zero(ra->Msg3_buffer);
NR_PRACH_RESOURCES_t *prach_resources = &ra->prach_resources;
prach_resources->preamble_tx_counter++;
if (prach_resources->preamble_tx_counter == ra->preambleTransMax + 1) {
// TODO indicate a Random Access problem to upper layers
} else {
// TODO handle msgA-TransMax (go back to 4-step if the threshold is reached)
// starting backoff time
nr_ra_backoff_setting(ra);
}
}
void nr_rar_not_successful(NR_UE_MAC_INST_t *mac)
{
LOG_W(MAC, "[UE %d] RAR reception failed\n", mac->ue_id);
@@ -1284,44 +1284,7 @@ void nr_rar_not_successful(NR_UE_MAC_INST_t *mac)
}
}
if (!ra_completed) {
// select a random backoff time according to a uniform distribution
// between 0 and the PREAMBLE_BACKOFF
uint32_t seed = (unsigned int)(rdtsc_oai() & ~0);
uint32_t random_backoff = rand_r(&seed) % ra->RA_backoff_limit; // in slots
nr_timer_setup(&ra->RA_backoff_timer, random_backoff, 1);
nr_timer_start(&ra->RA_backoff_timer);
}
}
// Handling failure of RA procedure @ MAC layer
// according to section 5 of 3GPP TS 38.321 version 16.2.1 Release 16
// todo:
// - complete handling of received contention-based RA preamble
void nr_ra_failed(NR_UE_MAC_INST_t *mac, uint8_t CC_id, NR_PRACH_RESOURCES_t *prach_resources, frame_t frame, int slot)
{
RA_config_t *ra = &mac->ra;
ra->ra_PreambleIndex = -1;
ra->ra_state = nrRA_UE_IDLE;
prach_resources->preamble_tx_counter++;
// when the Contention Resolution is considered not successful
// stop timeAlignmentTimer
nr_timer_stop(&mac->time_alignment_timer);
if (prach_resources->preamble_tx_counter == ra->preambleTransMax + 1) {
LOG_D(NR_MAC,
"[UE %d][%d.%d] Maximum number of RACH attempts (%d) reached, selecting backoff time...\n",
mac->ue_id,
frame,
slot,
ra->preambleTransMax);
prach_resources->preamble_tx_counter = 1;
prach_resources->preamble_power_ramping_step += 2; // 2 dB increment
prach_resources->ra_preamble_rx_target_power = get_ra_preamble_rx_target_power(ra, mac->current_UL_BWP->scs);
nr_ra_backoff_setting(ra);
}
}
openair2/LAYER2/NR_MAC_UE/nr_ue_procedures.c
+7 -8
View File
@@ -3501,9 +3501,7 @@ static int nr_ue_validate_successrar(uint8_t *pduP,
nr_timer_stop(&ra->response_window_timer);
nr_ra_succeeded(mac, gNB_index, frameP, slot);
} else if (!ra_success) {
// nr_ra_failed(mac, CC_id, &ra->prach_resources, frameP, slot);
ra->ra_state = nrRA_UE_IDLE;
ra->RA_active = 0;
nr_ra_backoff_setting(ra);
}
}
} else { // RAPID
@@ -3706,7 +3704,8 @@ void nr_ue_process_mac_pdu(NR_UE_MAC_INST_t *mac, nr_downlink_indication_t *dl_i
mac_len = 6;
if (ra->ra_state == nrRA_WAIT_CONTENTION_RESOLUTION) {
LOG_I(MAC, "[UE %d]Frame %d Contention resolution identity: 0x%02x%02x%02x%02x%02x%02x Terminating RA procedure\n",
LOG_D(NR_MAC,
"[UE %d]Frame %d Contention resolution identity: 0x%02x%02x%02x%02x%02x%02x Terminating RA procedure\n",
mac->ue_id,
frameP,
pduP[1],
@@ -3716,15 +3715,15 @@ void nr_ue_process_mac_pdu(NR_UE_MAC_INST_t *mac, nr_downlink_indication_t *dl_i
pduP[5],
pduP[6]);
nr_timer_stop(&ra->contention_resolution_timer);
bool ra_success = check_ra_contention_resolution(&pduP[1], ra->cont_res_id);
if (ra->RA_active && ra_success) {
nr_ra_succeeded(mac, gNB_index, frameP, slot);
} else if (!ra_success) {
// TODO: Handle failure of RA procedure @ MAC layer
// nr_ra_failed(module_idP, CC_id, prach_resources, frameP, slot); // prach_resources is a PHY structure
ra->ra_state = nrRA_UE_IDLE;
ra->RA_active = false;
// consider this Contention Resolution not successful and discard the successfully decoded MAC PDU
nr_ra_contention_resolution_failed(ra);
return;
}
}
break;
openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c
+3 -1
View File
@@ -192,7 +192,9 @@ void update_mac_timers(NR_UE_MAC_INST_t *mac)
bool alignment_timer_expired = nr_timer_tick(&mac->time_alignment_timer);
if (alignment_timer_expired)
handle_time_alignment_timer_expired(mac);
nr_timer_tick(&mac->ra.contention_resolution_timer);
bool contention_resolution_expired = nr_timer_tick(&mac->ra.contention_resolution_timer);
if (contention_resolution_expired)
nr_ra_contention_resolution_failed(&mac->ra);
for (int j = 0; j < NR_MAX_SR_ID; j++)
nr_timer_tick(&mac->scheduling_info.sr_info[j].prohibitTimer);
nr_timer_tick(&mac->scheduling_info.sr_DelayTimer);