5G NR NSA Network Access Issues and Possible Root Cause

5G NR NSA (New Radio Non-Standalone) refers to the deployment of 5G radio access technology alongside an existing LTE (Long-Term Evolution) network. In this mode, the 5G network relies on the LTE network for certain functions, such as the core network. Network access issues in 5G NR NSA can arise from various factors, and identifying the root cause involves understanding the complex interplay of different components. Here's a technical explanation of potential network access issues and their possible root causes:

1. Initial Access Failures:
   • Root Cause: One common issue is the failure of user devices to establish an initial connection with the 5G NR cell.
   • Possible Causes:
     • Synchronization Issues: Devices may have difficulty synchronizing with the 5G NR cell, leading to failures in the initial access procedure.
     • Cell Selection Problems: Devices may struggle to select the appropriate 5G NR cell for connection, possibly due to interference or incorrect cell configuration.
2. Handover Failures:
   • Root Cause: Handover failures occur when a user device attempts to switch from LTE to 5G NR or vice versa during ongoing communication.
   • Possible Causes:
     • Interference: High interference levels in the radio environment can impact the success of handovers between LTE and 5G NR.
     • Inadequate Measurement Reporting: Improper reporting of signal measurements by the device can lead to incorrect handover decisions.
3. Random Access Issues:
   • Root Cause: Random access problems occur during the procedure where a device tries to access the network for various reasons, such as initiating a new connection or re-establishing a lost connection.
   • Possible Causes:
     • Contention: Increased contention due to a high number of devices attempting random access simultaneously can result in collisions and access failures.
     • Incorrect Parameters: Misconfigurations in random access parameters can lead to unsuccessful access attempts.
4. Radio Resource Control (RRC) Connection Failures:
   • Root Cause: Failures in establishing or maintaining the RRC connection between the user device and the network.
   • Possible Causes:
     • Congestion: Network congestion can prevent the establishment of the RRC connection.
     • Protocol Mismatch: Incompatibility or misconfiguration of RRC protocols between the device and the network.
5. Core Network Issues:
   • Root Cause: Problems within the core network, especially in the interaction between the LTE and 5G components.
   • Possible Causes:
     • Inadequate Interworking: Incompatibility or insufficient interworking between LTE and 5G core networks.
     • Core Network Failures: Failures in the core network elements responsible for supporting 5G NR NSA deployments.