Hybrid Beamforming is the most practical and effective choice for dense urban environments with high user mobility. It combines the advantages of analog beamforming (for coarse beam steering to handle rapid user movement and multipath) with digital beamforming (for fine-grained, user-specific precoding to mitigate interference). Pure Digital Beamforming is often too computationally complex and expensive for massive MIMO in this scenario, while fixed or purely analog beams lack the agility and precision needed.

A PLMN (Public Land Mobile Network) ID mismatch is a common cause for SCTP association failures even when IP connectivity is fine. The gNodeB and AMF must be configured with matching PLMN values (MCC and MNC) for the N2 interface establishment to succeed. Restarting nodes is not a systematic approach, VLAN issues would typically affect IP connectivity (already verified), and adjusting timers is unlikely to resolve a fundamental configuration mismatch.

Intermittent high UL packet loss with good signal strength strongly points to an uplink synchronization issue. If the UE’s Timing Advance is incorrect or it loses UL sync, its transmissions will arrive at the gNodeB at the wrong time, causing collisions and packet loss. This directly impacts delay-sensitive services like VoNR. While other options are valid checks, the TA and UL sync status are the most direct technical parameters related to the observed symptom.

Radio Resource Partitioning is the fundamental RAN mechanism for true isolation. It allows the gNodeB to allocate guaranteed minimum amounts of resource blocks (e.g., PRBs, slots) to a specific network slice, preventing one slice (like bursty eMBB) from starving another (like Massive IoT). NSSAI is for identification, QoS Flow management handles priority within a slice, and DECOR is a core network function. Effective slicing in the RAN hinges on enforceable resource partitioning.

In NSA (EN-DC), traffic steering between the LTE anchor (MeNB) and the 5G NR booster (SgNB) is primarily governed by QoS Flow mapping. The core network assigns a specific 5QI to each flow (e.g., low-latency 5QI for gaming, high-throughput 5QI for downloads). The RAN uses this to decide which bearer (LTE only, NR only, or split) to map the flow to. Split Bearer is a bearer type that enables this, but the decision logic is driven by the 5QI. Load balancing and coverage events are not granular enough for application-aware steering.

If UEs can initiate RRC Setup but fail during the radio resource configuration phase, it often indicates a problem with the fundamental system information they are using. An error in SIB1 scheduling means the UE cannot correctly receive other critical SIBs (like SIB2 which contains common radio resource config), leading to this specific failure. NR-ARFCN mismatch would prevent initial synchronization. Beamforming weights and PRACH root sequences are more related to initial access before RRC Setup.

In 5G TDD networks, a critical requirement is that all neighboring cells must use the same UL/DL pattern (or a subset thereof) at the same time. If not synchronized, one cell’s downlink transmission can cause severe interference to another cell’s uplink reception (cross-link interference). This is a network-wide planning parameter, not a per-cell or per-UE optimization. While SSB alignment is important, the primary driver for uniform configuration is interference coordination.

Beamforming (especially with massive MIMO) focuses energy to extend the effective reach of the C-Band downlink. However, the uplink is often the limiting factor due to lower UE transmit power. Supplementary Uplink (SUL) addresses this by pairing the C-Band downlink with an uplink on a lower frequency band (e.g., 1.8 GHz), which has better propagation and coverage. This combination is a key strategy for practical C-Band deployment. The other options improve capacity or efficiency but do not directly solve the fundamental coverage challenge.

The NG Setup procedure is specifically the initialization and configuration exchange between the gNodeB (RAN) and the Access and Mobility Management Function (AMF) in the 5G core. This procedure occurs over the N2 interface. Therefore, N2 interface signaling logs (capturing the NGAP protocol messages) will contain the direct success/failure responses and the specific cause codes (e.g., transport resource unavailable, unknown PLMN) needed for root cause analysis.

Hybrid Beamforming is the most practical and effective choice for dense urban environments with high user mobility. It combines the advantages of analog beamforming (for coarse beam steering to handle rapid user movement and multipath) with digital beamforming (for fine-grained, user-specific precoding to mitigate interference). Pure Digital Beamforming is often too computationally complex and expensive for massive MIMO in this scenario, while fixed or purely analog beams lack the agility and precision needed.0