Partial Handover for Continuous Data Transmission in Wireless Systems
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Solution Overview
Problem
Existing handover procedures in LTE systems disrupt data transmission, as they require resetting and re-establishing MAC, PDCP, and RLC entities, which prevents communication with the source cell during the Make-Before-Break handover process, leading to potential data loss and service interruptions.
Innovation Solution
A method and apparatus for performing a partial handover in LTE systems, where the UE continues to exchange data with the source cell until specific conditions are met, allowing for delayed RRC procedures such as PDCP, RLC re-establishment, and security key derivation, enabling seamless transition to the target cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional handover procedure is used, then handover from source cell to target cell is completed, but data transmission is interrupted and service continuity is lost
Solution Approach 1:
The UE performs RACH procedure and establishes connection with target cell before releasing connection with source cell. This preliminary establishment of target cell connection ensures that data transmission can continue seamlessly once source cell connection is released, eliminating service interruption.
Solution Approach 2:
The handover procedure maintains data transmission continuity by keeping source cell connection active during target cell connection establishment. The UE continues to exchange data with source cell until target cell connection is fully established, ensuring no break in data transmission service.
2Productivity
If connection with source cell is released early during handover, then resources are freed up, but data transmission is disrupted
Solution Approach 1:
The UE completes RACH procedure and connection establishment with target cell before releasing source cell connection. This preliminary action ensures target cell is ready to immediately take over data transmission, allowing source cell resources to be efficiently released only when necessary.
Solution Approach 2:
The handover procedure dynamically adjusts the timing of source cell connection release based on target cell connection establishment status. The source cell connection is maintained as long as target cell connection is not yet ready, and is released only when target cell can immediately assume data transmission responsibilities.
Data Source
AI summary
For continuous data transmission during a handover procedure, Make-Before-Break handover may be introduced, which maintains source evolved NodeB (eNB) connection after reception of radio resource control (RRC) message for handover. In order to reduce ambiguity of Make-Before-Break handover, the present invention provides receiving a handover command from a network, after receiving the handover command from the network, keeping exchanging data with a source cell, stopping exchanging data with the source cell when a condition is met, and after stopping exchanging data with the source cell, starting exchanging data with a target cell.