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Handle UE context setup resp for HO: trigger reconfiguration on source

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In this commit, handle the reception of a UE context setup response, in
the case of handover. In that case, store the gNB-DU UE ID and C-RNTI of
the UE at the target DU, and trigger a reconfiguration towards the UE at
the source DU via the callback.

To ensure that the CU-UP's PDCP is SN-aligned with the UE, use
cuup_notify_reestablishment() to reset the bearers with PDCP
reestablishment, which has already been implemented in the last commit.

Co-authored-by: batuhanduyuler <batuhan.duyuler@firecell.io>
Co-authored-by: rmagueta <rmagueta@allbesmart.pt>
This commit is contained in:
Robert Schmidt
2024-10-25 20:10:26 +02:00
co-authored by batuhanduyuler rmagueta
parent 7b163f1688
commit 0e20c4c257
2 changed files with 96 additions and 2 deletions
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openair2/RRC/NR/rrc_gNB.c
+21 -1
View File
@@ -1864,7 +1864,27 @@ static void rrc_CU_process_ue_context_setup_response(MessageDef *msg_p, instance
cuup_notify_reestablishment(rrc, UE);
}
rrc_gNB_generate_dedicatedRRCReconfiguration(rrc, UE);
if (UE->ho_context == NULL) {
rrc_gNB_generate_dedicatedRRCReconfiguration(rrc, UE);
} else {
// case of handover
// handling of "target CU" information
DevAssert(UE->ho_context->target != NULL);
DevAssert(resp->crnti != NULL);
UE->ho_context->target->du_ue_id = resp->gNB_DU_ue_id;
UE->ho_context->target->new_rnti = *resp->crnti;
uint8_t xid = rrc_gNB_get_next_transaction_identifier(0);
UE->xids[xid] = RRC_DEDICATED_RECONF;
uint8_t buffer[NR_RRC_BUF_SIZE] = {0};
int size = rrc_gNB_encode_RRCReconfiguration(rrc, UE, xid, NULL, buffer, sizeof(buffer), true);
DevAssert(size > 0 && size <= sizeof(buffer));
// TODO N2 38.413 sec 9.3.1.21: admitted PDU sessions (in UE), Target to
// Source Transparent Container (9.3.1.21) which encodes the RRC
// reconfiguration above
UE->ho_context->target->ho_req_ack(rrc, UE, buffer, size);
}
}
static void rrc_CU_process_ue_context_release_request(MessageDef *msg_p)
openair2/RRC/NR/rrc_gNB_mobility.c
+75 -1
View File
@@ -31,6 +31,11 @@
#include "rrc_gNB_UE_context.h"
#include "openair2/F1AP/f1ap_ids.h"
#include "MESSAGES/asn1_msg.h"
#include "nr_pdcp/nr_pdcp_oai_api.h"
#include "openair3/SECU/key_nas_deriver.h"
/* declared in rrc_gNB.c: should be cleaned up through helper function? useful? */
extern mui_t rrc_gNB_mui;
typedef enum { HO_CTX_BOTH, HO_CTX_SOURCE, HO_CTX_TARGET } ho_ctx_type_t;
static nr_handover_context_t *alloc_ho_ctx(ho_ctx_type_t type)
@@ -198,6 +203,75 @@ void nr_rrc_trigger_n2_ho(gNB_RRC_INST *rrc, int nr_cgi, uint8_t *ho_prep_info,
}
*/
typedef struct deliver_ue_ctxt_modification_data_t {
gNB_RRC_INST *rrc;
f1ap_ue_context_modif_req_t *modification_req;
sctp_assoc_t assoc_id;
} deliver_ue_ctxt_modification_data_t;
static void rrc_deliver_ue_ctxt_modif_req(void *deliver_pdu_data, ue_id_t ue_id, int srb_id, char *buf, int size, int sdu_id)
{
DevAssert(deliver_pdu_data != NULL);
deliver_ue_ctxt_modification_data_t *data = deliver_pdu_data;
data->modification_req->rrc_container = (uint8_t*)buf;
data->modification_req->rrc_container_length = size;
data->rrc->mac_rrc.ue_context_modification_request(data->assoc_id, data->modification_req);
}
static void rrc_gNB_trigger_reconfiguration_for_handover(gNB_RRC_INST *rrc, gNB_RRC_UE_t *ue, uint8_t *rrc_reconf, int rrc_reconf_len)
{
f1_ue_data_t ue_data = cu_get_f1_ue_data(ue->rrc_ue_id);
TransmActionInd_t transmission_action_indicator = TransmActionInd_STOP;
RETURN_IF_INVALID_ASSOC_ID(ue_data.du_assoc_id);
f1ap_ue_context_modif_req_t ue_context_modif_req = {
.gNB_CU_ue_id = ue->rrc_ue_id,
.gNB_DU_ue_id = ue_data.secondary_ue,
.plmn.mcc = rrc->configuration.mcc[0],
.plmn.mnc = rrc->configuration.mnc[0],
.plmn.mnc_digit_length = rrc->configuration.mnc_digit_length[0],
.nr_cellid = rrc->nr_cellid, // TODO target cell ID
.servCellId = 0, // TODO: correct value?
.ReconfigComplOutcome = RRCreconf_success,
.transm_action_ind = &transmission_action_indicator,
};
deliver_ue_ctxt_modification_data_t data = {.rrc = rrc,
.modification_req = &ue_context_modif_req,
.assoc_id = ue_data.du_assoc_id};
int srb_id = 1;
nr_pdcp_data_req_srb(ue->rrc_ue_id,
srb_id,
rrc_gNB_mui++,
rrc_reconf_len,
(unsigned char *const)rrc_reconf,
rrc_deliver_ue_ctxt_modif_req,
&data);
}
static void nr_rrc_f1_ho_acknowledge(gNB_RRC_INST *rrc, gNB_RRC_UE_t *UE, uint8_t *rrc_reconf_buf, uint32_t rrc_reconf_len)
{
// N2/Xn HO: fill with UE caps, as-context, rrc reconf, send to source CU
// also, fill the UE->rnti from the new one (in F1 case, happens after
// confirmation of ue ctxt modif
// F1 HO: handling of "source CU" information
DevAssert(UE->ho_context->source != NULL);
rrc_gNB_trigger_reconfiguration_for_handover(rrc, UE, rrc_reconf_buf, rrc_reconf_len);
LOG_A(NR_RRC, "HO acknowledged: Send reconfiguration for UE %u/RNTI %04x...\n", UE->rrc_ue_id, UE->rnti);
/* Re-establish SRB2 according to clause 5.3.5.6.3 of 3GPP TS 38.331
* (SRB1 is re-established with RRCReestablishment message)
*/
int srb_id = 2;
if (UE->Srb[srb_id].Active) {
nr_pdcp_entity_security_keys_and_algos_t security_parameters;
/* Derive the keys from kgnb */
nr_derive_key(RRC_ENC_ALG, UE->ciphering_algorithm, UE->kgnb, security_parameters.ciphering_key);
nr_derive_key(RRC_INT_ALG, UE->integrity_algorithm, UE->kgnb, security_parameters.integrity_key);
security_parameters.integrity_algorithm = UE->integrity_algorithm;
security_parameters.ciphering_algorithm = UE->ciphering_algorithm;
nr_pdcp_reestablishment(UE->rrc_ue_id, srb_id, true, &security_parameters);
}
}
void nr_rrc_trigger_f1_ho(gNB_RRC_INST *rrc, gNB_RRC_UE_t *ue, nr_rrc_du_container_t *source_du, nr_rrc_du_container_t *target_du)
{
DevAssert(rrc != NULL);
@@ -212,7 +286,7 @@ void nr_rrc_trigger_f1_ho(gNB_RRC_INST *rrc, gNB_RRC_UE_t *ue, nr_rrc_du_contain
// here: target Cell is preselected, target CU has access to UE information
// and therefore also the PDU sessions. Orig RRC reconfiguration should be in
// handover preparation information
ho_req_ack_t ack = NULL;
ho_req_ack_t ack = nr_rrc_f1_ho_acknowledge;
ho_success_t success = NULL;
ho_cancel_t cancel = NULL;
nr_initiate_handover(rrc, ue, source_du, target_du, buf, size, ack, success, cancel);