Tuesday, 6 October 2015

LTE FDD Network Planning & Optimization System-wrong core network configuration led to a LTE site can’t be resided

 Incident Description (Incident Phenomena)
A field, there is a LTE site which belongs to island. When the DT engineer arrived the site, prepared to SSV test, the terminal could’t receive the LTE singal. After setted as the freedom mode, the terminal selected 3G network. If locked LTE mode, the terminal would show no singal.  
 Networking Environment
 Problem Cause Analysis
Firstly we checked the test terminal. Before, we tested other LTE sites with this terminal, the service was ok. So the test terminal is normal.
Then we checked the LTE site status from EMS.There showed no alarm about the site,and the power,RSSI,VSWR ,all were normal from diagnostic test. The configuration of this site is the same with others.
Since all the existing sites are belong to island, distributed in different citys, the individual site problem is needed to analyse by signaling from UDT and test software.
 Solution
UDT signaling analysis,

Every release command was sent out by S1 port from core network, the reason belonged to normal release, then the enode released UE, led access failure.
TEMS signaling analysis,


After MME let UE feedback EMS information, UE sent back the EMS information response including APN set as internet.mtn.ug,then the core network rejected. We confirmed that the APN setting was correct, other normal sites used the same APN setting.  
From the above troubleshooting, wo excluded the wireless side and APN setting problem. The problem was needed to troubleshooting by core network engineer, analysed the reason the core network rejected.  
After the core network engineer troubleshot, found some wrong configuration with this site in core network side, corrected, the LTE singal problem was solved.

Budi Prasetyo

About Budi Prasetyo

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