Sunday, 4 October 2015

LTE FDD Network Planning & Optimization System-Wrong PRACH Parameter setting cause UE can not access LTE network

 Problem Cause Analysis
 

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 the transmit power of RRU RRU has power, it is normal
4) )Open the signaling trace tool, and call customer let UE always attempt to attach LTE network, but l no any signal report to the whole cell.
 Solution
 

1.1 Parameters check, and found problems PRACH access parameter Settings

PRACH access parameters in the Starting RB number of random access preamble set to 91, as follows:
 
Starting RB number of random access preamble 91 is for 20M FDD cell, but the issue eNodeB is 10M FDD cell.
So change “Starting RB number of random access preamble” from 91 into 41Data synchronization,  retest and find everything recover.
 
 Summary and Notes
 
Starting RB number of random access preamble 91 is for 20M FDD cell, but the issue eNodeB is 10M FDD cell.
So change “Starting RB number of random access preamble” from 91 into 41Data synchronization,  retest and find everything recover.

Budi Prasetyo

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