Dual-Active Protocol Stack Handover for Wireless Terminals
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Solution Overview
Problem
Current handover procedures in wireless communication systems experience data interruption due to the break-before-make approach, which increases terminal and operation complexity, as they require simultaneous data processing from both source and target cells using multiple protocol layers.
Innovation Solution
A method that maintains connection with the source cell until handover to the target cell is complete, allowing data transmission and reception with both cells, and includes configuration messages for adding candidate PCells, performing random access, and switching between cells to minimize interruption time and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If DAPS handover scheme is used to maintain connection with source cell during handover, then data interruption time is reduced, but terminal complexity and handover operation complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring the target cell before handover execution. The network side prepares the target cell's resources, configuration parameters, and connection settings in advance, so that when handover is triggered, the terminal can quickly establish connection without complex real-time configuration. This reduces both interruption time and operational complexity.
Solution Approach 2:
The patent uses the network side (core network or serving base station) as an intermediary to coordinate the handover process. The network manages the dual-active protocol stack, coordinates resource allocation between source and target cells, and handles the switching logic. This intermediary approach simplifies terminal complexity by centralizing the coordination function in the network.
2Loss of time
If DAPS handover scheme is used to maintain connection with source cell during handover, then data interruption time is reduced, but handover operation complexity increases
Solution Approach 1:
The network side performs preliminary actions by pre-establishing the target cell's connection parameters, resource allocations, and protocol stack configurations before handover is needed. This preparation eliminates complex real-time decision-making during handover execution, reducing operational complexity while maintaining continuous data transmission.
Solution Approach 2:
The network acts as an intermediary that manages the complexity of maintaining dual connections and coordinating protocol stack operations. By centralizing the handover coordination in the network, the terminal's operational complexity is reduced, as it only needs to execute predefined switching instructions rather than managing complex coordination logic.
3Device complexity
If break-before-make handover approach is used, then handover procedure is simple, but data interruption occurs during handover
Solution Approach 1:
The patent implements continuity of useful action by maintaining the data transmission path during handover through the dual-active protocol stack. The terminal simultaneously maintains connections with both source and target cells, allowing data to flow continuously without interruption. This is achieved by preparing the target cell in advance and switching data paths seamlessly during handover execution.
Data Source
AI summary
A handover method of a first terminal in a wireless communication system may comprise: transmitting a first measurement report message to a first cell that is a primary cell (PCell); receiving, from the first cell, one or more first configuration messages for one or more target cells determined according to the first measurement report message; adding each of the one or more target cells as a candidate PCell based on the one or more first configuration messages; and performing data transmission and reception with at least one cell among the first cell and the one or more candidate PCells.