Tuesday, 22 September 2015

LTE FDD Network Planning & Optimization System-RAB setup success ratio is 0%

1 Background

B project customer feedback, under a certain eNodeB, UE can receive LTE signal, but UE is unable to access, RRC success setup ratio is normal, but the e-RAB success setup ratio is 0%,
 Networking Environment

1.1 Check the eNodeB

1) Step1: First check the site alarms, it is no alarms;
2) Step2: Check the status of the site in dynamic query tools, eNodeB state is normal;
3) Step3: query eNodeB version: v3.10.10 P31, version is normal;
4) Step4: query the transmit power of RRU RRU has power, it is normal
 Problem Cause Analysis

1.1 Open the signaling trace tool, and call customer let UE always attempt to attach LTE network, failure signal is below

Main failures are “initial context setup failure”.
Customer change the mobile phone, the result is the same, and not once was a success, success rate index statistics for RRC is normal, e - RAB the success rate of 0%.



1.1 e – RAB setup failures from OMC statistical

 e – RAB setup failures from OMC statistical are below two kinds:
Number of Initial SAE Bearers Setup Failures due to ENB Admission Failure
Number of Initial SAE Bearers Setup Failures due to Other Reason
Statistical results
 Summary and Notes

1.1 Check the configuration

query OMC configuration, found that OMC is configured with two operators, the MNC of second operator is wrong; And in Service Map table "service and DSCP mapping" mapping the second operator records, lead to negotiate error with EPC, delete the second operator records, and "service and DSCP mapping" mapping the first operator records, synchronous data, the problem is solved

Budi Prasetyo

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