Use MeasurementTimingConfiguration to look up SSB ARFCN when needed
MeasTimingConfig may not come with F1 Setup Request: some DUs send it with the DU configuration update. Handle this gracefully by checking for MTC before using it.
This commit is contained in:
Robert Schmidt
+16
-80
@@ -186,79 +186,12 @@ static int get_ssb_scs(const f1ap_served_cell_info_t *cell_info)
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return cell_info->mode == F1AP_MODE_TDD ? cell_info->tdd.tbw.scs : cell_info->fdd.dl_tbw.scs;
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}
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static int get_dl_arfcn(const f1ap_served_cell_info_t *cell_info)
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static int get_ssb_arfcn(const nr_rrc_du_container_t *du)
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{
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return cell_info->mode == F1AP_MODE_TDD ? cell_info->tdd.freqinfo.arfcn : cell_info->fdd.dl_freqinfo.arfcn;
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}
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static int get_dl_bw(const f1ap_served_cell_info_t *cell_info)
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{
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return cell_info->mode == F1AP_MODE_TDD ? cell_info->tdd.tbw.nrb : cell_info->fdd.dl_tbw.nrb;
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}
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static int get_ssb_arfcn(const f1ap_served_cell_info_t *cell_info, const NR_MIB_t *mib, const NR_SIB1_t *sib1)
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{
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DevAssert(cell_info != NULL && sib1 != NULL && mib != NULL);
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const NR_FrequencyInfoDL_SIB_t *freq_info = &sib1->servingCellConfigCommon->downlinkConfigCommon.frequencyInfoDL;
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AssertFatal(freq_info->scs_SpecificCarrierList.list.count == 1,
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"cannot handle more than one carrier, but has %d\n",
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freq_info->scs_SpecificCarrierList.list.count);
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AssertFatal(freq_info->scs_SpecificCarrierList.list.array[0]->offsetToCarrier == 0,
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"cannot handle offsetToCarrier != 0, but is %ld\n",
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freq_info->scs_SpecificCarrierList.list.array[0]->offsetToCarrier);
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long offsetToPointA = freq_info->offsetToPointA;
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long kssb = mib->ssb_SubcarrierOffset;
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uint32_t dl_arfcn = get_dl_arfcn(cell_info);
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int scs = get_ssb_scs(cell_info);
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int band = get_dl_band(cell_info);
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uint64_t freqpointa = from_nrarfcn(band, scs, dl_arfcn);
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uint64_t freqssb = 0;
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// 3GPP TS 38.211 sections 7.4.3.1 and 4.4.4.2
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// for FR1 offsetToPointA and k_SSB are expressed in terms of 15 kHz SCS
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// for FR2 offsetToPointA is expressed in terms of 60 kHz SCS and k_SSB expressed in terms of the subcarrier spacing provided
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// by the higher-layer parameter subCarrierSpacingCommon
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// FR1 includes frequency bands from 410 MHz (ARFCN 82000) to 7125 MHz (ARFCN 875000)
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// FR2 includes frequency bands from 24.25 GHz (ARFCN 2016667) to 71.0 GHz (ARFCN 2795832)
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if (dl_arfcn >= 82000 && dl_arfcn < 875000)
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freqssb = freqpointa + 15000 * (offsetToPointA * 12 + kssb) + 10ll * 12 * (1 << scs) * 15000;
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else if (dl_arfcn >= 2016667 && dl_arfcn < 2795832)
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freqssb = freqpointa + 60000 * offsetToPointA * 12 + (1 << scs) * 15000 * (kssb + 10ll * 12);
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else
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AssertFatal(false, "Invalid absoluteFrequencyPointA: %u\n", dl_arfcn);
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int band_size_hz = get_supported_bw_mhz(band > 256 ? FR2 : FR1, scs, get_dl_bw(cell_info)) * 1000 * 1000;
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uint32_t ssb_arfcn = to_nrarfcn(band, freqssb, scs, band_size_hz);
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LOG_D(NR_RRC,
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"freqpointa %ld Hz/%d offsetToPointA %ld kssb %ld scs %d band %d band_size_hz %d freqssb %ld Hz/%d\n",
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freqpointa,
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dl_arfcn,
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offsetToPointA,
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kssb,
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scs,
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band,
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band_size_hz,
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freqssb,
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ssb_arfcn);
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if (RC.nrmac) {
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// debugging: let's test this is the correct ARFCN
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// in the CU, we have no access to the SSB ARFCN and therefore need to
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// compute it ourselves. If we are running in monolithic, though, we have
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// access to the MAC structures and hence can read and compare to the
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// original SSB ARFCN. If the below creates problems, it can safely be
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// taken out (but the reestablishment will likely not work).
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const NR_ServingCellConfigCommon_t *scc = RC.nrmac[0]->common_channels[0].ServingCellConfigCommon;
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uint32_t scc_ssb_arfcn = *scc->downlinkConfigCommon->frequencyInfoDL->absoluteFrequencySSB;
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AssertFatal(ssb_arfcn == scc_ssb_arfcn,
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"mismatch of SCC SSB ARFCN original %u vs. computed %u! Note: you can remove this Assert, the gNB might run but UE "
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"connection instable\n",
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scc_ssb_arfcn,
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ssb_arfcn);
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}
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return ssb_arfcn;
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DevAssert(du != NULL && du->mtc != NULL);
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/* format has been verified when accepting MeasurementTimingConfiguration */
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NR_MeasTimingList_t *mtlist = du->mtc->criticalExtensions.choice.c1->choice.measTimingConf->measTiming;
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return mtlist->list.array[0]->frequencyAndTiming->carrierFreq;
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}
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///---------------------------------------------------------------------------------------------------------------///
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@@ -582,13 +515,8 @@ static void rrc_gNB_generate_defaultRRCReconfiguration(const protocol_ctxt_t *co
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f1ap_served_cell_info_t *cell_info = &du->setup_req->cell[0].info;
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int scs = get_ssb_scs(cell_info);
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int band = get_dl_band(cell_info);
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NR_MeasConfig_t *measconfig = NULL;
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if (du->mib != NULL && du->sib1 != NULL) {
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/* we cannot calculate the default measurement config without MIB&SIB1, as
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* we don't know the DU's SSB ARFCN */
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uint32_t ssb_arfcn = get_ssb_arfcn(cell_info, du->mib, du->sib1);
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measconfig = get_defaultMeasConfig(ssb_arfcn, band, scs);
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}
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uint32_t ssb_arfcn = get_ssb_arfcn(du);
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NR_MeasConfig_t *measconfig = get_defaultMeasConfig(ssb_arfcn, band, scs);
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NR_SRB_ToAddModList_t *SRBs = createSRBlist(ue_p, false);
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NR_DRB_ToAddModList_t *DRBs = createDRBlist(ue_p, false);
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@@ -996,7 +924,7 @@ static void rrc_gNB_generate_RRCReestablishment(rrc_gNB_ue_context_t *ue_context
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uint8_t xid = rrc_gNB_get_next_transaction_identifier(module_id);
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ue_p->xids[xid] = RRC_REESTABLISH;
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const f1ap_served_cell_info_t *cell_info = &du->setup_req->cell[0].info;
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uint32_t ssb_arfcn = get_ssb_arfcn(cell_info, du->mib, du->sib1);
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uint32_t ssb_arfcn = get_ssb_arfcn(du);
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int size = do_RRCReestablishment(ue_context_pP, buffer, RRC_BUF_SIZE, xid, cell_info->nr_pci, ssb_arfcn);
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LOG_I(NR_RRC, "[RAPROC] UE %04x Logical Channel DL-DCCH, Generating NR_RRCReestablishment (bytes %d)\n", ue_p->rnti, size);
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@@ -1286,6 +1214,14 @@ static void rrc_handle_RRCReestablishmentRequest(gNB_RRC_INST *rrc,
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goto fallback_rrc_setup;
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}
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if (du->mtc == NULL) {
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// some UEs don't send MeasurementTimingConfiguration, so we don't know the
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// SSB ARFCN and can't do reestablishment. handle it gracefully by doing
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// RRC setup procedure instead
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LOG_E(NR_RRC, "no MeasurementTimingConfiguration for this cell, cannot perform reestablishment\n");
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goto fallback_rrc_setup;
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}
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/* TODO: start timer in ITTI and drop UE if it does not come back */
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// update with new RNTI, and update secondary UE association
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@@ -166,14 +166,10 @@ void rrc_gNB_process_f1_setup_req(f1ap_setup_req_t *req, sctp_assoc_t assoc_id)
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}
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}
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// MTC is mandatory, but some DUs don't send it in the F1 Setup Request, so
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// "tolerate" this behavior, despite it being mandatory
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NR_MeasurementTimingConfiguration_t *mtc =
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extract_mtc(cell_info->measurement_timing_config, cell_info->measurement_timing_config_len);
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if (!mtc) {
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LOG_W(RRC, "cannot decode MeasurementTimingConfiguration of DU ID %ld, rejecting\n", req->gNB_DU_id);
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f1ap_setup_failure_t fail = {.cause = F1AP_CauseProtocol_semantic_error};
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rrc->mac_rrc.f1_setup_failure(assoc_id, &fail);
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return;
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}
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const f1ap_gnb_du_system_info_t *sys_info = req->cell[0].sys_info;
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NR_MIB_t *mib = NULL;
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