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The BER in the Optical Path of the OptiX Metro 1000 Equipment Becomes Large Transiently Due to the Interference from the GPRS Services of the Movable Ring Monitoring Equipment on Sites

Publication Date:  2012-07-25 Views:  43 Downloads:  0
Issue Description
In the telecommunications room of a mobile carrier, after the air-conditioners of sites are turned on, the services are transiently interrupted on the OptiX Metro 1000 equipment on certain sites. In addition, ROOF, R_LOF, and SYN_BAD alarms are transiently reported and the optical board transiently reports the large RS BER. The transient interruption interval is about 20 minutes, that is, the interval of turning on and turning off the air-conditioners. The fault disappears after the customer removes the sampling lines equipped with air-conditioners.  
Alarm Information
ROOF
R_LOF
SYN_BAD 

 
Handling Process
1. Observe Huawei SDH equipment and the movable ring monitoring equipment. They are installed closely. Re-connect the sampling lines equipped with air-conditioners. Turn on and turn off the air-conditioners repeatedly. The services on these sites are interrupted transiently.
2. Shut down the movable ring monitoring equipment. Then, the services on these sites are restored to normal. After that, start the movable ring monitoring equipment and power off the GPRS wireless transmission module on the movable ring monitoring equipment. The equipment runs properly. Therefore, you can preliminarily infer that the OptiX Metro 1000 equipment may be affected by the GPRS wireless transmission module.
3. After powering off the movable ring monitoring equipment, use different mobile stations (MSs) to move to the OptiX Metro 1000 equipment and perform GPRS network access. The services on these sites are interrupted transiently. Therefore, it is confirmed that the OptiX Metro 1000 equipment is affected by GPRS signals.
4. It is suspected that the interference from GPRS signals is too strong because the movable ring monitoring equipment is installed right over the OptiX Metro 1000 equipment. Move the movable ring monitoring equipment to the position 15 cm higher than the original position and re-connect the transformer and the GPRS wireless transmission module. All are normal no matter whether the air-conditioners are turned on or off.
5. Test certain sites installed with the PDH transmission equipment of other manufacturers. The GPRS also causes transient service interruption.
6. For the sites with the similar phenomenon, adjust the installation position of the movable ring monitoring equipment of company X. Then, the fault is rectified. The field experience shows that the distance between the movable ring monitoring equipment and the transmission equipment must be at least over 20 cm. If conditions permit, the transmission equipment and the movable ring monitoring system should be installed in different network cabinets. 

 
Root Cause
The movable ring monitoring system of company X uses the wireless transmission mode to form a network. Interference is caused to the OptiX Metro 1000 equipment when the wireless transmission module (GPRS) transmits and receives signals. 

 
Suggestions
1 The GPRS wireless transmission module in the movable ring monitoring system of company X directly communicates with a site. Once the power supply, access control, air-conditioner, or other ambient equipment in the telecommunications room is faulty, the GPRS wireless transmission module actively sends monitoring data such as alarms to the site and the site sends the monitoring data to the movable ring monitoring NMS in the MN center. In this case, the launched power of the GPRS wireless transmission module increases and may affect the normal running of the transmission equipment.
2  Suppose that the movable ring monitoring system provided by Jiaxun and the OptiX Metro 1000 equipment are installed in the same network cabinet. If the large RS BER is transiently reported and the movable ring monitoring system provided by Jiaxun reports substantive alarm data, you are first advised to shut down the movable ring monitoring system of company X to check whether the monitoring system is affected by external interference. When the movable ring monitoring system and the OptiX Metro 1000 equipment are installed in the same network cabinet in the existing network, you are advised to adjust their installation distance to decrease interference strength.
3  The test on the existing network shows that the OptiX Metro 1000 V3 equipment has a weaker capability against GPRS interference from the MS than the OptiX Metro 1000 V2 equipment. During field maintenance, you are advised to avoid using an MS to start a conversation when being close to the transmission equipment, especially for the GPRS services. Otherwise, transmission bit errors are caused. 
 

END