From e958822a73092efef723c774161e17fcd86a5e4d Mon Sep 17 00:00:00 2001
From: francescomani <email@francescomani.it>
Date: Wed, 4 Dec 2024 18:21:27 +0100
Subject: [PATCH] Procedures for Contention Resolution
---
openair2/LAYER2/NR_MAC_UE/mac_proto.h | 7 +-
openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c | 93 ++++++--------------
openair2/LAYER2/NR_MAC_UE/nr_ue_procedures.c | 15 ++--
openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c | 4 +-
4 files changed, 40 insertions(+), 79 deletions(-)
diff --git a/openair2/LAYER2/NR_MAC_UE/mac_proto.h b/openair2/LAYER2/NR_MAC_UE/mac_proto.h
index 2157a6c1c83..c494d477f5e 100644
--- a/openair2/LAYER2/NR_MAC_UE/mac_proto.h
+++ b/openair2/LAYER2/NR_MAC_UE/mac_proto.h
@@ -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
diff --git a/openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c b/openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c
index 02afecec814..f198f4f17a2 100644
--- a/openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c
+++ b/openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c
@@ -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);
}
}
diff --git a/openair2/LAYER2/NR_MAC_UE/nr_ue_procedures.c b/openair2/LAYER2/NR_MAC_UE/nr_ue_procedures.c
index a77067395f7..8d42075c48e 100644
--- a/openair2/LAYER2/NR_MAC_UE/nr_ue_procedures.c
+++ b/openair2/LAYER2/NR_MAC_UE/nr_ue_procedures.c
@@ -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;
diff --git a/openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c b/openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c
index a5f129e3129..c7a6d99c332 100644
--- a/openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c
+++ b/openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c
@@ -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);
--
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