DC

Dual Connectivity

Radio Access Network

Introduced in Rel-12

Architecture allowing UE to connect to two base stations simultaneously for increased throughput.

Description

Dual Connectivity (DC) enables a UE to utilize radio resources provided by two distinct schedulers located in two eNodeBs (Master eNB and Secondary eNB) connected via non-ideal backhaul.

Unlike Carrier Aggregation which requires ideal backhaul, DC is designed for scenarios where the backhaul between nodes has higher latency. The Master eNB (MeNB) handles the control plane while both nodes contribute to user plane throughput.

DC is particularly useful in heterogeneous networks combining macro cells with small cells.

Purpose & Motivation

Dual Connectivity was introduced to:

- Increase user throughput by using resources from multiple nodes - Improve mobility robustness (anchor at macro, capacity from small cell) - Enable efficient small cell deployments with non-ideal backhaul - Provide load balancing between network layers

Key Features

  • Master eNB (MeNB) and Secondary eNB (SeNB)
  • Split bearer architecture
  • Non-ideal backhaul tolerance
  • Independent PDCP for MCG and SCG
  • Synchronized and asynchronous operation

Evolution Across Releases

Rel-12Initial

Initial DC architecture with Master and Secondary eNB

EN-DC (E-UTRA-NR Dual Connectivity) for 5G NSA deployment

NE-DC (NR-E-UTRA DC) with NR as master, NR-NR DC

Defining Specifications

SpecificationTitle
E-UTRAN Overall Description
Study on Small Cell Enhancements
Multi-connectivity