Radio Base Station UL CLTD Control Removal During Soft Handover
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Solution Overview
Problem
In radio communications networks, during soft handover scenarios, the ineffective usage of radio resources leads to reduced performance due to the lack of signaling between the old and new control cells in Uplink Closed Loop Transmit Diversity (UL CLTD) configurations, resulting in continued resource allocation by the old control cell even after the UE is instructed to listen to the new control cell.
Innovation Solution
A mechanism is introduced where a radio network controller sends a 'UL CLTD removal' indicator to the old radio base station, allowing it to cease its control operations, thereby enabling the efficient transfer of control to the new cell and optimizing radio resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the old control cell continues to allocate radio resources during soft handover, then the UE can maintain connection diversity, but radio resources are wasted and network performance is reduced
Solution Approach 1:
The RNC sends a removal indication to the old control cell before the handover is complete, allowing the old cell to pre-release its radio resources. This preliminary action ensures that resources are freed in advance, eliminating waste while the UE maintains connection diversity through the new control cell until handover completion.
Solution Approach 2:
The system implements feedback signaling where the RNC monitors handover status and sends removal indications to the old control cell based on this feedback. This feedback mechanism ensures that the old cell continues allocating resources only when necessary for connection diversity, and releases them promptly when the new control cell takes over, optimizing resource utilization.
2Productivity
If signaling is implemented between RNC and old control cell to remove UL CLTD control, then radio resource efficiency is improved, but system complexity increases
Solution Approach 1:
The removal indication signaling is integrated into the existing RNC-NBAP interface framework, allowing the same signaling infrastructure to serve multiple functions: handover coordination, resource management, and UL CLTD control. This multi-functionality approach improves radio resource efficiency without requiring separate dedicated signaling paths, thus limiting the increase in system complexity.
Solution Approach 2:
The system changes the state parameter of UL CLTD control by sending a removal indication that transitions the old control cell from an active control state to an inactive state. This parameter change approach simplifies the signaling complexity by using state transitions rather than complex continuous coordination, improving resource efficiency through clear state management.
Data Source
AI summary
Embodiments herein relate to a method in a radio base station for handling Uplink Closed Loop Transmit Diversity, UL CLTD. The radio base station is configured to control UL CLTD of a user equipment (10) served by the radio base station. The radio base station receives from a radio network controller (15) an indication indicating a change in the UL CLTD. The radio base station then removes UL CLTD related operation for the user equipment based on the received indication.