TRX faulty on the RRU after commissioning

Publication Date:  2016-02-29 Views:  780 Downloads:  0
Issue Description

After commissioning  the DBS3900 cell, all the boards and status of the board (RRU and GTMU) show running and active, but when you check on the alarms the cell is out of service and it does not transmit signal, cannot make calls

Alarm Information

On the management alarm console this alarm will appear cell out of service and when you move the cursor close to RRU, TRX status show faulty and channel status is faulty.

Handling Process

Steps to take in solving the fault:

1. Verify if the software version of the BBU is the same as the one for RRU.
2. Check TRX channels if they are in IDLE/DEDICATED mode
3. Reset RRU and BBU - (Can reset on site or remotely mostly preffered on site hard reset)

Root Cause

GSMR uses E1 solution to integrate BSC and DBS, for redundacy purpose 2 ports per site, when the E1 ports configured are crossed around with the physical connection, the port appear to be visible on the BSC but it cannot transfer any data hence it reflect the cell out of service.

Solution

Change the E1 port configuration on the U2000 according to the physical installation, reset the site and wait for 15 minutes while the BSC is mapping the physical and the logical port. when alarm clears and TRX appear normal perform the following test

1. check if TRX is either in one of the two state idle/dedicated
2. on site engineer can receive signal
3. on site engineer can make calls according to their categories.

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