Macro-Assisted Multi-Connectivity for 5G mmWave Handover Reliability
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Solution Overview
Problem
The existing LTE Dual Connectivity architecture is not optimized for 5G mmWave small cells, leading to reliability issues and service degradation due to beamforming limitations, directional coverage, and high handover failure rates, especially at cell edges, where 5G demands uniform UE service experience.
Innovation Solution
A novel Macro-assisted Multi-Connectivity (MC) scheme that extends the LTE Dual Connectivity architecture with a multi-way packet data convergence protocol (PDCP) bearer split based on channel quality and resource availability, enabling make-before-break mobility by allowing simultaneous data transmission with multiple base stations, thereby enhancing mobility management and bandwidth aggregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LTE Dual Connectivity architecture is used for 5G mmWave small cells, then network integration is achieved, but reliability deteriorates due to beamforming limitations and directional coverage
Solution Approach 1:
The patent segments the connectivity architecture into multiple independent paths: a primary mmWave small cell connection for high-speed data and a secondary macro cell connection for reliable control signaling. This segmentation allows each connection type to fulfill its strengths while mitigating the weaknesses of the other, resolving the contradiction between network integration adaptability and connection reliability.
Solution Approach 2:
The patent applies local quality by assigning different functional roles to different network nodes: mmWave small cells provide high-capacity data transmission in specific localized areas, while macro cells provide omnidirectional coverage and reliable control signaling across broader areas. This localized functional differentiation resolves the contradiction by optimizing each node for its specific purpose.
2Productivity
If beamforming is used in mmWave small cells, then data rate is improved, but handover failure rate increases due to directional coverage limitations
Solution Approach 1:
The patent implements preliminary action through make-before-break handover: the UE establishes a new connection with the target small cell before releasing the connection with the current small cell. The macro cell connection is maintained throughout the handover process as a safety net, ensuring that control signaling continuity is preserved even during the transition, thus preventing handover failures.
Solution Approach 2:
The macro cell connection serves as an intermediary during handover transitions between mmWave small cells. When beamforming causes link disruption or handover failure, the macro cell provides an alternative communication path that bridges the gap, allowing the UE to maintain connectivity and complete the handover process without failure.
3Device complexity
If control channel is anchored solely to master eNB in DuCo, then network control is simplified, but service degradation occurs at cell edges due to signal weakness
Solution Approach 1:
The patent applies local quality by allowing flexible control channel anchoring: for UEs at cell edges or experiencing poor conditions from the master eNB, the control channel can be anchored to a secondary eNB instead. This localized adaptation of control channel location resolves the contradiction by maintaining simple overall control architecture while providing enhanced service quality for specific UEs at cell edges through alternative anchoring points.
Data Source
AI summary
A novel Macro-assisted Multi-Connectivity (MC) mobility scheme for UEs traversing clusters of (mmWave) small cells (small-BS or SBS) under the coverage of the same 5G or LTE Macro-cell (macro-BS or MBS) is proposed. It keeps the same Control/User split scheme and C-Plane anchor at MBS, same as in LTE Dual Connectivity (DuCo or DC), yet extending DuCo with a multi-connectivity split bearer user plane. For example, MBS adopts a multi-way packet data convergence protocol (PDCP) bearer split based on routing weighted by channel quality, SBS's resource availability, etc. with or without inter-BS flow control. Utilizing the MC user plane, a macro-assisted make-before-break MC mobility can be enabled.