nacc_fsm: Add support for NACC with UTRAN and E-UTRAN cells
The NACC procedure in OsmoPCU currently only supports NACC with GERAN
cells. When an UTRAN or E-UTRAN cell is proposed in the
PacketCellChangeNotification, then the FSM is immediately terminated,
meaning that the NACC procedure can not commence.
When the NACC procedure is carried out for UTRAN or E-UTRAN cells, the
PCU will not send any system information to the UE. Instead it
immediately sends a PacketCellChangeContinue message. This also means
that we do not carry out any RAN Information Requests in the background.
This patch adds logic to detect if the proprosed cell is an UTRAN or
E-UTRAN cell and the adds a new transition to the FSM so that a short
route to NACC_ST_TX_CELL_CHG_CONTINUE can be taken.
Related: OS#6044
Change-Id: I96280f0ec5955ed3cb17641bf4118496c929bdac
diff --git a/src/nacc_fsm.c b/src/nacc_fsm.c
index c513423..6ccfee9 100644
--- a/src/nacc_fsm.c
+++ b/src/nacc_fsm.c
@@ -191,7 +191,7 @@
uint8_t tfi_is_dl = tbf_direction(tbf) == GPRS_RLCMAC_DL_TBF;
uint8_t tfi = tbf_tfi(tbf);
uint8_t container_id = 0;
- write_packet_cell_change_continue(mac_control_block, 1, rrbp, tfi_is_dl, tfi, true,
+ write_packet_cell_change_continue(mac_control_block, 1, rrbp, tfi_is_dl, tfi, ctx->neigh_key_present,
ctx->neigh_key.tgt_arfcn, ctx->neigh_key.tgt_bsic, container_id);
LOGP(DNACC, LOGL_DEBUG, "+++++++++++++++++++++++++ TX : Packet Cell Change Continue +++++++++++++++++++++++++\n");
rc = encode_gsm_rlcmac_downlink(&bv, mac_control_block);
@@ -270,19 +270,90 @@
return 0;
}
-static int fill_neigh_key_from_bts_pkt_cell_chg_not(struct neigh_cache_entry_key *neigh_key,
+static int fill_neigh_key_from_bts_pkt_cell_chg_not(struct nacc_fsm_ctx *ctx,
const struct gprs_rlcmac_bts *bts,
const Packet_Cell_Change_Notification_t *notif)
{
+ const Target_Cell_GSM_Notif_t *notif_gsm;
+ const Target_Cell_3G_Notif_t *notif_3g;
+ const Target_Cell_4G_Notif_t *notif_4g;
+
+ memset(&ctx->neigh_key, 0, sizeof(ctx->neigh_key));
+ ctx->neigh_key_present = false;
+
switch (notif->Target_Cell.UnionType) {
- case 0: /* GSM */
- neigh_key->local_lac = bts->cgi_ps.rai.lac.lac;
- neigh_key->local_ci = bts->cgi_ps.cell_identity;
- neigh_key->tgt_arfcn = notif->Target_Cell.u.Target_Cell_GSM_Notif.ARFCN;
- neigh_key->tgt_bsic = notif->Target_Cell.u.Target_Cell_GSM_Notif.BSIC;
+ case 0: /* GSM */
+ notif_gsm = ¬if->Target_Cell.u.Target_Cell_GSM_Notif;
+ LOGPFSML(ctx->fi, LOGL_NOTICE, "TargetCell: RAT=GSM, ARFCN=%u, BSIC=%u\n",
+ notif_gsm->ARFCN, notif_gsm->BSIC);
+
+ ctx->neigh_key.local_lac = bts->cgi_ps.rai.lac.lac;
+ ctx->neigh_key.local_ci = bts->cgi_ps.cell_identity;
+ ctx->neigh_key.tgt_arfcn = notif_gsm->ARFCN;
+ ctx->neigh_key.tgt_bsic = notif_gsm->BSIC;
+ ctx->neigh_key_present = true;
return 0;
default:
- return -ENOTSUP;
+ switch (notif->Target_Cell.u.Target_Other_RAT_Notif.UnionType) {
+ case 0: /* UTRAN */
+ notif_3g = ¬if->Target_Cell.u.Target_Other_RAT_Notif.u.Target_Cell_3G_Notif;
+ if (notif_3g->Exist_FDD_Description) {
+ LOGPFSML(ctx->fi, LOGL_NOTICE,
+ "TargetCell: RAT=UTRAN, FDD-ARFCN=%u => no system information provided.\n",
+ notif_3g->FDD_Target_Cell_Notif.FDD_ARFCN);
+ } else if (notif_3g->Exist_TDD_Description) {
+ LOGPFSML(ctx->fi, LOGL_NOTICE,
+ "TargetCell: RAT=UTRAN, TDD-ARFCN=%u => no system information provided.\n",
+ notif_3g->TDD_Target_Cell.TDD_ARFCN);
+ }
+ return 0;
+ default:
+ switch (notif->Target_Cell.u.Target_Other_RAT_Notif.u.Target_Other_RAT_2_Notif.UnionType) {
+ case 0: /* E-UTRAN (and older RAT) */
+ notif_4g =
+ ¬if->Target_Cell.u.Target_Other_RAT_Notif.u.Target_Other_RAT_2_Notif.u.Target_Cell_4G_Notif;
+ notif_3g = ¬if_4g->Target_Cell_3G_Notif;
+ if (notif_4g->Exist_Arfcn) {
+ LOGPFSML(ctx->fi, LOGL_NOTICE, "TargetCell: RAT=GSM, ARFCN=%u, BSIC=%u\n",
+ notif_4g->Arfcn, notif_4g->bsic);
+ ctx->neigh_key.local_lac = bts->cgi_ps.rai.lac.lac;
+ ctx->neigh_key.local_ci = bts->cgi_ps.cell_identity;
+ ctx->neigh_key.tgt_arfcn = notif_4g->Arfcn;
+ ctx->neigh_key.tgt_bsic = notif_4g->bsic;
+ ctx->neigh_key_present = true;
+ return 0;
+ }
+ if (notif_4g->Exist_3G_Target_Cell) {
+ if (notif_3g->Exist_FDD_Description) {
+ LOGPFSML(ctx->fi, LOGL_NOTICE,
+ "TargetCell: RAT=UTRAN, FDD-ARFCN=%u => no system information provided.\n",
+ notif_3g->FDD_Target_Cell_Notif.FDD_ARFCN);
+ } else if (notif_3g->Exist_TDD_Description) {
+ LOGPFSML(ctx->fi, LOGL_NOTICE,
+ "TargetCell: RAT=UTRAN, TDD-ARFCN=%u => no system information provided.\n",
+ notif_3g->TDD_Target_Cell.TDD_ARFCN);
+ }
+ return 0;
+ }
+ if (notif_4g->Exist_Eutran_Target_Cell) {
+ LOGPFSML(ctx->fi, LOGL_NOTICE,
+ "TargetCell: RAT=E-UTRAN, EARFCN=%u, CI=%u => no system information provided.\n",
+ notif_4g->Target_EUTRAN_Cell.EARFCN,
+ notif_4g->Target_EUTRAN_Cell.Physical_Layer_Cell_Identity);
+ return 0;
+ }
+
+ /* TODO: do something meaningful with an Eutran_Ccn_Measurement_Report, in case it is
+ * provided. */
+
+ LOGPFSML(ctx->fi, LOGL_NOTICE, "TargetCell: (none, invalid)\n");
+ return -EINVAL;
+ default:
+ LOGPFSML(ctx->fi, LOGL_NOTICE,
+ "TargetCell: RAT=CSG-UTRAN|CSG-EUTRAN, (not supported)\n");
+ return -ENOTSUP; /* TODO: Add support */
+ }
+ }
}
}
@@ -316,14 +387,23 @@
{
struct gprs_rlcmac_bts *bts = ctx->ms->bts;
struct neigh_cache_entry_key neigh_key;
+ int rc;
- if (fill_neigh_key_from_bts_pkt_cell_chg_not(&neigh_key, bts, notif) < 0) {
- LOGPFSML(ctx->fi, LOGL_NOTICE, "TargetCell type=0x%x not supported\n",
- notif->Target_Cell.UnionType);
+ rc = fill_neigh_key_from_bts_pkt_cell_chg_not(ctx, bts, notif);
+ if (rc < 0) {
+ /* (see comment below) */
if (ctx->fi->state != NACC_ST_TX_CELL_CHG_CONTINUE)
nacc_fsm_state_chg(ctx->fi, NACC_ST_TX_CELL_CHG_CONTINUE);
return;
+ } else if (!ctx->neigh_key_present) {
+ /* In case no neighbour key information is present, (This would be the case for UTRAN or EUTRAN cells)
+ * then we will not provide any system information. Instead we will send the PacketCellChangeContinue
+ * message immediately. This also applies in the case of re-transmissions. See also: 3GPP TS 48.018,
+ * section 8c.6.1. */
+ nacc_fsm_state_chg(ctx->fi, NACC_ST_TX_CELL_CHG_CONTINUE);
+ return;
}
+
/* If tgt cell changed, restart resolving it */
if (!neigh_cache_entry_key_eq(&ctx->neigh_key, &neigh_key)) {
ctx->neigh_key = neigh_key;
@@ -341,17 +421,21 @@
struct nacc_fsm_ctx *ctx = (struct nacc_fsm_ctx *)fi->priv;
struct gprs_rlcmac_bts *bts = ctx->ms->bts;
Packet_Cell_Change_Notification_t *notif;
+ int rc;
switch (event) {
case NACC_EV_RX_CELL_CHG_NOTIFICATION:
notif = (Packet_Cell_Change_Notification_t *)data;
- if (fill_neigh_key_from_bts_pkt_cell_chg_not(&ctx->neigh_key, bts, notif) < 0) {
- LOGPFSML(fi, LOGL_NOTICE, "TargetCell type=0x%x not supported\n",
- notif->Target_Cell.UnionType);
+ rc = fill_neigh_key_from_bts_pkt_cell_chg_not(ctx, bts, notif);
+ if (rc < 0)
osmo_fsm_inst_term(fi, OSMO_FSM_TERM_ERROR, NULL);
- } else {
+ else if (!ctx->neigh_key_present) {
+ /* In case no neighbour key information is present, (This would be the case for UTRAN or EUTRAN
+ * cells) then we will not provide any system information. Instead we will send the
+ * PacketCellChangeContinue message immediately. See also: 3GPP TS 48.018, section 8c.6.1. */
+ nacc_fsm_state_chg(fi, NACC_ST_TX_CELL_CHG_CONTINUE);
+ } else
nacc_fsm_state_chg(fi, NACC_ST_WAIT_RESOLVE_RAC_CI);
- }
break;
default:
OSMO_ASSERT(0);
@@ -382,7 +466,6 @@
}
/* CGI-PS not in cache, resolve it using BSC Neighbor Resolution CTRL interface */
-
LOGPFSML(fi, LOGL_DEBUG, "No CGI-PS found in cache, resolving " NEIGH_CACHE_ENTRY_KEY_FMT "...\n",
NEIGH_CACHE_ENTRY_KEY_ARGS(&ctx->neigh_key));
@@ -622,7 +705,8 @@
.in_event_mask =
X(NACC_EV_RX_CELL_CHG_NOTIFICATION),
.out_state_mask =
- X(NACC_ST_WAIT_RESOLVE_RAC_CI),
+ X(NACC_ST_WAIT_RESOLVE_RAC_CI) |
+ X(NACC_ST_TX_CELL_CHG_CONTINUE),
.name = "INITIAL",
.action = st_initial,
},
diff --git a/src/nacc_fsm.h b/src/nacc_fsm.h
index ec6db2e..cab62af 100644
--- a/src/nacc_fsm.h
+++ b/src/nacc_fsm.h
@@ -47,6 +47,7 @@
struct osmo_fsm_inst *fi;
struct GprsMs* ms; /* back pointer */
struct neigh_cache_entry_key neigh_key; /* target cell info from MS */
+ bool neigh_key_present; /* target cell info from MS is present */
struct osmo_cell_global_id_ps cgi_ps; /* target cell info resolved from req_{arfcn+bsic} */
struct si_cache_value si_info; /* SI info resolved from SGSN, to be sent to MS */
size_t si_info_bytes_sent; /* How many bytes out of si_info->si_len were already sent to MS */