Active Set Update Message for HS-DSCH Cell Change
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Solution Overview
Problem
Current handover mechanisms for mobile radio devices, specifically during High Speed Downlink Shared Channel (HS-DSCH) cell changes, require separate Radio Bearer Control procedures, leading to performance degradation and potential connection breaks due to sequential execution of Active Set Update and Radio Bearer Control procedures.
Innovation Solution
Incorporating HS-DSCH information into the Active Set Update message to enable a combined Active Set Update and Serving HS-DSCH cell change procedure, thereby avoiding the need for a separate Radio Bearer Control procedure and reducing transmission breaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate Radio Bearer Control procedure is performed before Active Set Update, then HS-DSCH information is properly updated, but transmission delay increases and connection reliability deteriorates
Solution Approach 1:
The patent combines the Active Set Update procedure and the Serving HS-DSCH cell change procedure into a single unified procedure. The RNC sends both the active set update message and the serving HS-DSCH cell change message simultaneously to the UE, eliminating the sequential execution delay and ensuring both procedures complete together, thus improving connection reliability without increasing transmission delay.
2Speed
If Active Set Update is performed first, then handover speed improves, but HS-DSCH transmission continuity deteriorates due to long break
Solution Approach 1:
The patent merges the Active Set Update and Serving HS-DSCH cell change into one simultaneous operation. The RNC prepares the new serving HS-DSCH cell and sends the combined update message to the UE in one step, allowing the UE to switch cells without interrupting HS-DSCH transmission, thus maintaining both fast handover speed and continuous transmission.
Solution Approach 2:
The RNC performs preliminary preparation of the new serving HS-DSCH cell before triggering the combined update. The target cell is pre-configured and ready to immediately take over HS-DSCH transmission when the UE receives the combined update message, ensuring no transmission break occurs during the handover.
3Device complexity
If separate procedures are used for Active Set Update and Serving HS-DSCH cell change, then procedure clarity is maintained, but signaling overhead increases and process complexity increases
Solution Approach 1:
The patent combines two separate RRC messages (Active Set Update message and Serving HS-DSCH cell change message) into a single unified message transmitted from the RNC to the UE. This reduces the number of signaling exchanges, lowers overhead, and simplifies the overall procedure while maintaining all necessary information for both updates.
Data Source
AI summary
Because the current RRC: ACTIVE SET UPDATE message presently used in soft handover does not contain HS-DSCH related information, which could be utilized for a Serving HS-DSCH cell change, a separate Radio Bearer Control procedure is needed between the UE (10) and the RNC (20) for carrying out the Serving HS-DSCH cell change. Should HS-DSCH related information—applicable to Serving HS-DSCH cell change—be added to the RRC: ACTIVE SET UPDATE message (32), an unnecessary Radio Bearer Control procedure is avoided, and the drawbacks of the current method are overcome.