Layer 3 (L3) Issues in LTE and Troubleshooting?

 

Step 1: Physical Layer (L1) - Check Signal Quality

• Use LTE_PHY_Connected_Mode_Intra_Freq_Meas to check:
• RSRP (Should be > -100 dBm)
• RSRQ (Should be > -10 dB)
• SINR (Should be > 5 dB)
• Action: If weak signal, move to a better location, retry connection.

Step 2: Synchronization Layer - Verify PCI & Timing

• Use LTE_PHY_Synchronization_Results to check:
• PSS/SSS Decoding
• MIB Decoding
• SIB1 Reception
• Action: If PSS/SSS fails, check PCI in LTE_RRC_Cell_Selection.

Step 3: RRC Layer - Analyse Connection Setup

• Use LTE_RRC_OTA: RRCConnectionRequest
• If missing RRC Connection Setup, check LTE_RRC_OTA: RRCConnectionReject
• Action: If rejected due to congestion, retry in a different cell.

Step 4: NAS Layer - Debug Authentication & Attach Issues

• Use LTE_NAS_EMM: Attach Request
• If rejected, check Attach Reject Cause
• Action: If authentication fails, check LTE_NAS_EMM: Authentication Reject.

 Step 5: ESM Layer - Debug PDN & Bearer Setup Issues

• Use LTE_NAS_ESM: PDN Connectivity Request
• If rejected, verify APN in PDN Connectivity Reject
• Action: Update APN settings, retry attach.