Hello Everyone
It is my Pleasure to share with You how to troubleshoot a specific Transmission Synchronization Fault Alarm includes below addresses
1- Classification and definition Common of Transmission Synchronization Faults
2- A Specific Transmission Synchronization Faults Alarm
v Fault Description alarm
v Root Causes of Alarm
v Troubleshooting Procedure
3- How to test the Clock quality
4- How to check status of the Clock
A) Reference clock source fault : the Fault occurs due to
· An external reference clock source loss,
· An external reference clock source unavailability due to unacceptable quality,
· An excessive phase or frequency deviation between the local oscillator
· An external reference clock source.
B) IP clock link fault : the Fault occurs when
· An IP clock link between the eNodeB and the clock server malfunctions.
C) System clock unlocked : the Fault occurs when
· A phase-locked loop in a board is unlocked.
D) Base station synchronization frame number error:
This error occurs when a synchronization frame number provided to a board is incorrect.
For example, an abrupt change of the frame number occurs when the pulse per second
(PPS)
Signals provided by the GPS are abnormal.
E) Time synchronization failure : the failure occurs when
The eNodeB fails to synchronize with the time synchronization server (for example, the NTP server).
2 A Specific Transmission Synchronization Faults Alarm
1. Fault Description alarm: the alarm appears when the external reference clocks for eNodeBs include GPS, synchronous Ethernet, IP-based clock, BITS, E1/T1, and TOD clocks and any exception in a reference clock will cause the eNodeB to be incapable of locking the reference clock.
2. Root Causes of Alarm : the alarm appears due to below reasons
A. The clock synchronization mode is not set to a specified mode.
B. The clock source is incorrectly added.
C. The clock working mode is incorrectly set for the eNodeB.
D. The external reference clock source is abnormal. For example, there is excessive Frequency offset.
E. The clock source is incorrectly selected, which leads to a clock lock failure
3. Troubleshooting Procedure :
1. Check the clock configuration for the eNodeB.
§ Check whether the clock synchronization mode is set to a specified mode.
§ Check whether the mode is set to the required one, for example, frequency synchronization or time synchronization. If the configuration is incorrect, change the mode to the required one.
§ Check whether the clock sources are correctly added.
§ Check whether the working mode of the clock is correctly set.
Notice: If the eNodeB needs to lock an external clock source, set the clock works in AUTO or MANUAL Mode
· * AUTO indicates that the system automatically selects a clock source based on the priority and availability of the clock sources.
* MANUAL indicates that a clock source must be specified by the user.
2. Check whether the external clock resources of the eNodeB work properly.
To check the status of an external clock source.
-. Run the DSP CLKSRC command which provide two fields in the command output:
@ License Authorized: it indicates that the clock source can be used.
-. Run the DSP LICINFO command to check whether the eNodeB synchronization function is enabled,
And all of the Allocated, Config, and Actual Used fields of the Enhanced Synchronization control item should = 1 to becomes enable
@ Clock Source State: it indicates to Link available Status of Reference Clock
-. Run the Command DSP IPCLKLINK, DSP SYNCETH, or DSP TOD to check The link availability.
@ on-IP clock : means that
The physical connection between the reference clock and the eNodeB is normal, and the eNodeB can properly receive clock signals sent by the reference clock.
@ IP clock : means that
The route from the eNodeB to the IP clock server is correct, and the eNodeB can properly receive clock signals sent by the IP clock server.
3. Check whether the physical connection and communication are normal between the eNodeB and the clock source.
-. Run the Command DSP GPS to check the number number of satellites must be greater than or equal to 4
4. Check whether the eNodeB can properly receive clock signals.
For a non-IP clock, clock signals are generated at the physical layer,
Therefore you can check only on the equipment that sends the clock signals They Are correctly sent
For an IP clock, you can check whether clock packets are correctly received by performing A Tracing task on the OSS or by analyzing packet headers on the nearest transmission equipment.
5. Check the eNodeB correctly selects a clock source.
- Run the Command SET CLKSRC to set reference Clock in Manual or Auto Mode Manually And Works properly
- Run the Command DSP CLKMODE to set reference clock in Manual Mode or Auto Mode Automatically and Works normally
6. Check the eNodeB correctly locks an external clock source.
- Run the DSP CLKSTAT command and ensure that the fields in the command output:
@ Current Clock Source: The clock source to be traced by the eNodeB.
@ Current Clock Source State: The value should be Normal.
@ PLL Status: The initial value should be fast tracking, and then Locked.
@ Clock Synchronization Mode: the configured clock synchronization mode of the eNodeB.
3- How to test the Clock quality : We can perform test for Clock Quality as follows
a) Run the Command STP CLKTST to stop clock quality test or Start
b) Run Command DSP CLKTST to check the clock quality test result
4- How to check status of the Clock: The clock status can be checked by running the DSP CLKSTAT command that provide below Values.
1) Current Clock Source indicates an unknown clock source.
2) Current Clock Source State indicates that the clock source is abnormal.
3) PLL Status indicates that the PLL status is abnormal.
4) Clock Synchronization Mode indicates that the clock synchronization mode is not set to a specified mode.
Thank you All for your understanding and Provide Feedback
Together everyone acheives More
Walid Nawar - PDAC -MVE
