Saturday, February 16, 2013

Subscriber Tracing in lte network

Subscriber Tracing in lte

Subscriber Tracing provides detailed information at the call level for the UE(user).

This is done in the lte network elements(MME,SGW,PGW) to measure the performance of network elements as well as the quality of services given to the user while using lte network.

Subscriber is also traced on demand of the user itself if it is not getting the good or appropriate quality of services from the lte network.

Operator can also trace some of the random users to check the quality of network.

Purpose of Subscriber Tracing in lte network:

-         Optimize the lte network performance.

-         Upon user demand if it is not getting the good quality of services from the network.

Operator applies the tracing on lte network elements for the specific users based on any one of the information provided by user i.e. IMSI or IMEI or MSISDN.


How Subscriber Tracing Works:


Two types of Subscriber Tracing can be done in network.

1.      Management based.

2.      Signaling based.

In management based tracing operator configure User id type (imsi(0) or imei(1) or msisdn(2)) and User id value (imsi value) on the lte node(pgw,sgw,mme) from which operator wants the traces for user.

Example: UE type – IMSI, UE value – 1234566778899, Node – PGW.

Now when the UE tries to attach with the lte network all the traces sent to TCE(external entity) by PGW.

Traces contains all the details related to the user like apn, plmn, imsi, rat type, qos parameters, user location etc.


In Signalling based tracing operator modify the configuration data in HSS with subscriber tracing enabled for the particular UE. Whenever UE attaches with the network, HSS sends Subscriber tracing enabled in the Subscription data in message Update Location answer and then MME forwards subscriber tracing parameter in Create Session request to SGW and then to PGW. Upon receving this parameter all the nodes starts tracing of that user and send all the trace records to TCE (Trace Collection entity).


Configuration for Signaling based Subscriber Tracing.

In HSS –

1.      Trace depth – Low, medium, high. (At what detailed level traces required).

2.      Nodes – SGW, MME, PGW. (On which of the node tracing is required).

3.      Interfaces – S5,S8,S11,Gx,Gn etc. (On which interface tracing is required).

4.      TCE Address – Ip address of TCE.  (Which ip address node should send traces).

Configuration for Management based Subscriber Tracing.


1.      Trace Depth – Low, medium, high.

2.      Type of Traces – XML , Syslog.

3.      TCE Address – Ip address of TCE.


Note: In operator based tracing two types of tracing is possible XML, Syslog.

but in Signaling based only xml tracing is possible.