EN-DC Secondary Node Addition Procedure

EN-DC (E-UTRAN New Radio - Dual Connectivity) secondary node addition refers to the process of adding a 5G NR (New Radio) cell as a secondary node to a connected LTE (Long-Term Evolution) cell, which serves as the primary node.

This dual connectivity setup enables the User Equipment (UE) :iphone: to simultaneously connect to both 4G and 5G networks, allowing for more efficient use of network resources and improved overall performance.
The process of EN-DC secondary node addition involves the following steps:

  1. Measurement Configuration :straight_ruler::

The primary LTE cell configures the UE to measure the signal strength and quality of nearby 5G NR cells. The UE then reports these measurements back to the network.

Example: Your 5G-capable smartphone :iphone: measures the signal strength of nearby 5G NR cells :satellite: while still connected to the 4G network.

  1. Secondary Node Addition Decision :brain::

Based on the measurement reports, the LTE cell decides whether to add a 5G NR cell as a secondary node. Factors such as signal strength, network load, and user requirements are considered.

Example: The network determines that adding a 5G NR cell :signal_strength: will improve your smartphone’s :iphone: performance and decides to establish a secondary node.

  1. RRC Reconfiguration :arrows_counterclockwise::

The primary LTE cell sends an RRC (Radio Resource Control) Reconfiguration message to the UE, instructing it to configure and establish a connection with the selected 5G NR cell.

Example: Your smartphone :iphone: receives instructions from the LTE network to establish a connection with the 5G NR cell :satellite:.

  1. Dual Connectivity Setup :gear::

The UE establishes a connection with the 5G NR cell as a secondary node while maintaining its connection with the LTE cell as the primary node.

Example: Your smartphone :iphone: successfully connects to both the 4G LTE and 5G NR cells, enabling seamless use of resources from both networks.

By leveraging EN-DC secondary node addition, users can enjoy faster data speeds :rocket:, lower latency, and enhanced connectivity, as their devices can access resources from both 4G and 5G networks simultaneously.

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