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Enable PDCP re-establishment for SRB1/SRB2 based on bitmap in createSRBlist

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This is necessary because the function was re-establishing PDCP only for SRB2
however according to specs 3GPP TS 38.331 RadioBearerConfig, PDCP shall be
re-established for SRB1 and/or SRB2 whenever the security key used for the
radio bearer changes, with some exceptions for SRB1 (i.e. when resuming
an RRC connection, or at the first reconfiguration after RRC connection
reestablishment in NR, do not re-establish PDCP for SRB1).

* the input param "reestablish" is converted into a bitmap to indicate
  whether PDCP should be re-established for the SRB1 and/or SRB2.
* For convenience the bitmap is 0-based, with index 1 corresponding to SRB1,
  index 2 to SRB2.

This commit is keeping the legacy re-establishment, that is re-establishment
of PCDP for SRB2 only.
This commit is contained in:
Guido Casati
2025-06-09 20:43:41 +02:00
parent a937eaec23
commit d18830f359
2 changed files with 26 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files
openair2/RRC/NR/nr_rrc_proto.h
+3
View File
@@ -40,6 +40,9 @@
#include "NR_RRCReconfiguration.h"
#include "RRC/NR/MESSAGES/asn1_msg.h"
#define SRB1 1
#define SRB2 2
void rrc_add_nsa_user(gNB_RRC_INST *rrc, x2ap_ENDC_sgnb_addition_req_t *m, sctp_assoc_t assoc_id);
void rrc_add_nsa_user_resp(gNB_RRC_INST *rrc, gNB_RRC_UE_t *UE, const f1ap_ue_context_setup_t *resp);
void rrc_release_nsa_user(gNB_RRC_INST *rrc, rrc_gNB_ue_context_t *ue_context);
openair2/RRC/NR/rrc_gNB.c
+23 -13
View File
@@ -270,12 +270,17 @@ unsigned int rrc_gNB_get_next_transaction_identifier(module_id_t gnb_mod_idP)
return tmp;
}
/**
* @brief Create srb-ToAddModList for RRCSetup and RRCReconfiguration messages
*/
static NR_SRB_ToAddModList_t *createSRBlist(gNB_RRC_UE_t *ue, bool reestablish)
/** @brief Create srb-ToAddModList for RRCSetup and RRCReconfiguration messages
* @param reestablish bitmap to indicates whether PDCP should be re-established
* for the SRB1 and/or SRB2. For convenience the bitmap is 0-based, with index 1
* corresponding to SRB1, index 2 to SRB2. 3GPP TS 38.331 RadioBearerConfig
* specifies that PDCP shall be re-established whenever the security key used
* for the radio bearer changes, with some expections for SRB1 (i.e. when resuming
* an RRC connection, or at the first reconfiguration after RRC connection
* reestablishment in NR, do not re-establish PDCP) */
static NR_SRB_ToAddModList_t *createSRBlist(gNB_RRC_UE_t *ue, uint8_t reestablish)
{
if (!ue->Srb[1].Active) {
if (!ue->Srb[SRB1].Active) {
LOG_E(NR_RRC, "Call SRB list while SRB1 doesn't exist\n");
return NULL;
}
@@ -284,9 +289,11 @@ static NR_SRB_ToAddModList_t *createSRBlist(gNB_RRC_UE_t *ue, bool reestablish)
if (ue->Srb[i].Active) {
asn1cSequenceAdd(list->list, NR_SRB_ToAddMod_t, srb);
srb->srb_Identity = i;
/* Set reestablishPDCP only for SRB2 */
if (reestablish && i == 2) {
/* Based on the bitmap, set reestablishPDCP for SRB1 and SRB2 */
if ((i == SRB1 || i == SRB2) && (reestablish & (1 << i))) {
asn1cCallocOne(srb->reestablishPDCP, NR_SRB_ToAddMod__reestablishPDCP_true);
} else {
DevAssert(!(reestablish & (1 << i)));
}
}
return list;
@@ -558,7 +565,7 @@ void free_RRCReconfiguration_params(nr_rrc_reconfig_param_t params)
/** @brief Prepare the instance of RRCReconfigurationParams to be pass to RRC encoding */
static nr_rrc_reconfig_param_t get_RRCReconfiguration_params(gNB_RRC_INST *rrc,
gNB_RRC_UE_t *UE,
bool srb_reestablish,
uint8_t srb_reest_bitmap,
bool drb_reestablish)
{
uint8_t xid = rrc_gNB_get_next_transaction_identifier(rrc->module_id);
@@ -620,8 +627,9 @@ static nr_rrc_reconfig_param_t get_RRCReconfiguration_params(gNB_RRC_INST *rrc,
UE->measConfig = measconfig;
// Re-establish PDCP for SRB2 only
NR_SRB_ToAddModList_t *SRBs = createSRBlist(UE, srb_reestablish);
NR_SRB_ToAddModList_t *SRBs = createSRBlist(UE, srb_reest_bitmap);
NR_DRB_ToAddModList_t *DRBs = createDRBlist(UE, drb_reestablish);
nr_rrc_reconfig_param_t params = {.cell_group_config = UE->masterCellGroup,
.transaction_id = xid,
.drb_config_list = DRBs,
@@ -662,7 +670,7 @@ static byte_array_t rrc_gNB_encode_RRCReconfiguration(gNB_RRC_INST *rrc, gNB_RRC
static void rrc_gNB_generate_dedicatedRRCReconfiguration(gNB_RRC_INST *rrc, gNB_RRC_UE_t *ue_p)
{
/* do not re-establish PDCP for any bearer */
nr_rrc_reconfig_param_t params = get_RRCReconfiguration_params(rrc, ue_p, false, false);
nr_rrc_reconfig_param_t params = get_RRCReconfiguration_params(rrc, ue_p, 0, false);
ue_p->xids[params.transaction_id] = RRC_PDUSESSION_ESTABLISH;
byte_array_t msg = rrc_gNB_encode_RRCReconfiguration(rrc, ue_p, params);
if (msg.len <= 0) {
@@ -1043,8 +1051,10 @@ static void rrc_gNB_process_RRCReestablishmentComplete(gNB_RRC_INST *rrc, gNB_RR
/* PDCP Reestablishment of DRBs according to 5.3.5.6.5 of 3GPP TS 38.331 (over E1) */
cuup_notify_reestablishment(rrc, ue_p);
/* Create srb-ToAddModList */
NR_SRB_ToAddModList_t *SRBs = createSRBlist(ue_p, true);
/* Create srb-ToAddModList, 3GPP TS 38.331 RadioBearerConfig:
* do not re-establish PDCP for SRB1, when resuming an RRC connection,
* or at the first reconfiguration after RRC connection reestablishment in NR */
NR_SRB_ToAddModList_t *SRBs = createSRBlist(ue_p, 1 << SRB2); // Re-establish PDCP for SRB2 only
/* Create drb-ToAddModList */
NR_DRB_ToAddModList_t *DRBs = createDRBlist(ue_p, true);
@@ -2153,7 +2163,7 @@ static void rrc_CU_process_ue_context_setup_response(MessageDef *msg_p, instance
* used for the radio bearer changes, with some expections for SRB1 (i.e. when resuming
* an RRC connection, or at the first reconfiguration after RRC connection reestablishment
* in NR, do not re-establish PDCP */
nr_rrc_reconfig_param_t params = get_RRCReconfiguration_params(rrc, UE, true, true);
nr_rrc_reconfig_param_t params = get_RRCReconfiguration_params(rrc, UE, (1 << SRB2), true);
params.transaction_id = xid;
byte_array_t msg = rrc_gNB_encode_RRCReconfiguration(rrc, UE, params);