Objectives After completing this learning element, the participant should be able to: • Explain basic alarms and alarm handling with Flexi Multiradio LTE BTS • Apply basic troubleshooting
Information sources in fault situations Use at least the following information sources when carrying out troubleshooting: Faults Faults are the primary source of information in most situations where troubleshooting is needed. Faults are printed out on the fault printer and/or other devices that you have specified for the network element. For instructions, see Checking BTS faults (NOLS). For fault descriptions, see Flexi Multiradio BTS Faults document (NOLS). BTS documentation You can find the latest information in the updated BTS documentation and Technical Notes. Access to the web pages is confined and information is delivered via your local Nokia Siemens Networks representative. Multiradio BTS LTE documentation is delivered via PIC (Product Information Center). The latest SW related documentation, such as List of Generic Faults and Release Note, can be found on the Multiradio BTS Technical Support web pages.
BTS log files Snapshot files are useful for troubleshooting purposes and must be attached when Resolve case is raised to Tier 3 level. Logs can be fetched locally or remotely with BTS Site Manager. For instructions, see BTS Site Manager Online Help(NOLS).
LOS Alarm LOS alarm is the root cause. X2AP and S1AP alarms are just the consequences in this case as physical interface is disconnected on which all applications (X2AP, S1AP,..) should run. Prerequisite for S1AP and X2AP setup is SCTP association which is in this case also not established. Therefore ‚Transport layer connection failure‘ is raised.
eNB is in „BTS configured“ state as S1AP link is down (no connection to MME) 10
S1 Interface failure If S1 interface failure is raised than SCTP association is established between eNB and MME (eNB and MME exchange SCTP heartbeats) but S1 setup request was not successful and S1AP is down.
Transport layer connection failure in X2 interface
Source: SCTP link for X2 interface. The transport path (SCTP) for connection to an adjacent BTS has broken. The reason for this can be an unplugged cable to the adjacent BTS. No transport path available to pursue operation on the faulty connection with the adjacent BTS.
Two iOMSs can be configured in eNB (Primary and Secondary). No alarm is raised in BTS Site Manager in case eNB is disconnected from iOMS. However, the link from NetAct to eNB (through iOMS) is broken.
GTP-U Path Failure alarm – continued Check GTP-U path configuration and IP address of the SGW in the Commissioning Wizard. If GTP-U supervision is set to the value different than zero supervision is switched on.
SGW IP address set GTPU object is not affecting user plane traffic. 25
VSWR alarm voltage standing wave ratio ; VSWR Ratio of maximum to minimum voltage in the standing wave pattern that appears along a transmission line. It is used as a measure of impedance mismatch between the transmission line and its load.
Alarms: „Radio resources switched off“ and „TX failure in MIMO“ are consequences of the VSWR alarm. 26
