Explanation Of Bss Alarms 1x2o5r

Explanation of BSS Alarms.  1. BSC LAPD communication Link Broken. This indicated that the problem is in the BSC end. I.e. E1 port is loose / Port Problem. This cannot be attributed to Transmission path Problem.  2. Site Abis control link broken The LAPD(OML) communication between the BSC and the BTS is broken. The likely scenario would be Transmission/ Power problem. It indicates that the Link between the BSC and BTS is completely broken and the site will only be restored after the link is established. In extreme cases, we will get the same alarm due to hardware failure, but the site will not be restored automatically. O&M Engineer need to attend and replace the Hardware.  Detailed information of abnormal Abis PM counters with link identification 

For example, Site Name=xxx, E1 port=yyy

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BER=xxx% (for 15 min, for 1 day, for 1 week, for 1 month)

The threshold for BER is in between ~ 10-6 to 10-3. This alarm will be generated if the E1 is having alarms exceeding threshold in a period of 15 Minutes. If the BER ceases in next 15 Minutes, then this Active Alarm will be cleared.  Meaning and counting criteria of PM counters related to Abis interface 

For example, BER counter is based on 3GPP TR.xxx.xxx (or proprietary)

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Counting meaning: bit error rate: ~ 10-6 to 10-3

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Unit: count, ratio in % rate, etc.: every 15 Minutes the performance report is extracted

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Counting criteria: counter increases when error rate is more than 10: Complete isolation will result in “Site Abis control link broken” Alarm.

In any BTS the threshold is between ~ 10-6 to 10-3 .However we do not have any technical documents from ZTE to understand the BTS sensitivity. In any conventional BTS, the sensitivity exceeding the threshold will result in Site fluctuation and eventually isolation of site.  Abnormal threshold values 

For example, when counter >> xx, call will be dropped

The customer will experience call drop between ~ 10-6 to 10-3 and eventual isolation after 10-3

Observations:

Going forward Transmission logs must be required to analyze the correct reason for site Fluctuation. In every provability the below mentioned Alarms will be appear in the Transmission MUX .

Loss of signal (LOS): During complete isolation of site.

Alarm Indication Signal (AIS): This is in response to LOS, Indicating error condition in the Link.

Remote Alarms Indication (RAI): Problem with remote NE. It is in response to LOS.