RiskofSolution:Non-Risk Operation
【ProblemDescription】
call drop public from EP680/EP720/EP820 to public.
【Problem Analysis】
1.EP720 EP820 call public,customer feedback abnormal,call drop
2.collect handset onekey logs
3.collect eapp onekey logs
4.find all UE is moving , located in a weak coverage area
5.The customer wants to find out the hardware differences of the EP720 through comparison tests.
【Root cause】
customer network issue,signal not ok
【Solution Description】
1.According to the terminal logs, the signal quality is poor when each service fails, which cannot meet the normal communication standard. It is recommended that the network signal be optimized onsite.
2.According to the onsite test result,10 exceptions are recorded, including 682, 680, and 720 exceptions for three times. The problem reproduction probability shows that no differences existbetween terminals of different models.
3.If you want to compare the differences between terminals, you are advised to select a fixed location and use three types of terminals to make calls for a certain number of times. In this way,the call drop rate is meaningful.
（1）2:36 PM ~2:44 PM Voice call failed due to network error /Call Drop
The cause is that the re-establishment is triggered on the 14.41 720 side when the number of uplink data packet retransmissions reaches the maximum. The cell IDis 158,
The downstream CSG did not record the information at that time, but the downstream signal quality was poor.
（2）2:53 PM~2:55 PM
According to the CSG, the down link signal quality is poor and the call quality cannot been sured.
（3）2:55 PM~3:06 PM
The call service is not detected, and the signal quality is poor.
（4）3:07 PM to 3:07 PM: The call fails to beset up. The gateway user rings for 30s and then automatically releases the call.
The last 682 call to a public network number was made around 13.56, and the signal quality was also poor.
（5）3:07 PM EP720(2099945) to Public
The UE is disconnected from the network after re-establishment, and the signal quality is poor.
