The UE Cannot Access the Cells Due to the Optical Module

In the early stage of network deployment in country P, 10 sites are deployed. The customer chooses the first three deployed sites for the test. The UE can access only one cell and fails to access other eight cells. According to the traced result on the OMT, the UE can receive the eNodeB signals. Therefore, the customer considers that this problem occurs on the entire network.

Handling Process

Possible causes:

1. Faults on the wireless network: BBUs and RRUs are faulty. Or the parameters (UE parameters, eNodeB parameters, and EPC parameters) are incorrectly set.

2. Transmission faults: Route configurations are incorrect and transmission faults occur.

3. EPC faults: Parameters used in connecting the wireless network are incorrectly set, and HSS registration parameters are incorrectly configured and NE parameters on the EPC are incorrect.
Problem analysis:

1. In a field commercial site, the UE can receive the MIB and SIB information sent by the eNodeB. Meanwhile, the UE can camp on the cells. Check the UE parameters, eNodeB parameters, and S1 status.
The result shows that they are normal. Therefore, the problem is not caused by improper radio parameter settings or transmission faults.

2. According to the messages on the OMT, the UE sends the MM_ATTACH_REQ&RRC_CONN_REQ message but does not receive the RRC connections setup message sent by the eNodeB. Therefore, the RRC connection is not set up. The problem occurs on the radio network side.
Check the modules of BBUs and RRUs.
The modules are normal. Therefore, the hardware may be faulty.

3. The UE cannot access the other eight cells. The following figure lists the result of observing the OMT key event message.

Solution