Active Set Management for DC-HSUPA Handover
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in handover processes between DC-HSUPA-capable and non-DC-HSUPA-capable nodes, leading to potential dropped calls due to rapid signal quality degradation during handovers.
Innovation Solution
Implementing either a legacy serving cell change procedure or an enhanced serving cell change procedure, where signaling from the network to user equipment includes information to enable the removal or adjustment of Active Sets during handovers from a cell with two uplink carriers to one with a single uplink carrier, specifically addressing the transition from a DC-HSUPA-capable node to a non-DC-HSUPA-capable node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a UE maintains two Active Sets when moving from a DC-HSUPA-capable cell to a non-DC-HSUPA-capable cell, then the UE can preserve dual-carrier operation benefits, but the handover process becomes complex and may cause dropped calls due to rapid signal quality degradation
Solution Approach 1:
The network node provides pre-configured information about the target cell's capability (DC-HSUPA or non-DC-HSUPA) before the handover occurs. This allows the UE to prepare the appropriate Active Set configuration in advance, avoiding complexity during the actual handover execution. The UE knows beforehand whether to maintain one or two Active Sets, enabling smoother transitions.
Solution Approach 2:
The system dynamically adjusts the Active Set configuration based on the handover scenario. When moving to a non-DC-HSUPA-capable cell, the UE dynamically removes the secondary Active Set. This dynamic adaptation allows the system to optimize performance for each specific handover case rather than maintaining a fixed complex configuration.
2Reliability
If the UE removes the secondary Active Set during handover to a non-DC-HSUPA-capable cell, then the handover succeeds more reliably, but the UE loses the ability to quickly resume dual-carrier operation
Solution Approach 1:
The network node provides pre-configured information about the target cell's capability before the handover occurs. This allows the UE to prepare the appropriate Active Set configuration in advance, avoiding complexity during the actual handover execution. The UE knows beforehand whether to maintain one or two Active Sets, enabling smoother transitions.
Solution Approach 2:
The network node provides feedback information about the target cell's DC-HSUPA capability to the UE during the handover preparation phase. This feedback mechanism enables the UE to make informed decisions about Active Set management, balancing reliability during handover with the ability to quickly resume dual-carrier operation when conditions permit.
3Ease of operation
If the network provides detailed capability information during handover signaling, then the UE can make informed Active Set decisions, but the signaling overhead increases
Solution Approach 1:
The network node provides capability information selectively and locally relevant to the handover scenario. Rather than transmitting complete cell configuration data, the network provides specific bits indicating DC-HSUPA capability status. This localized information approach gives the UE exactly what it needs for Active Set decisions without unnecessary signaling overhead.
Solution Approach 2:
The handover signaling uses parameter changes in existing messages to convey capability information. Instead of adding new signaling messages or fields, the network modifies existing parameters (such as adding a capability indicator bit to existing RRC messages) to encode the DC-HSUPA capability status. This efficient parameter utilization minimizes signaling overhead while providing sufficient information for UE decision-making.
Data Source
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AI summary
A system and method enable handover from a DC-HSUPA-capable node in a cellular wireless network to a non-DC-HSUPA-capable node. According to various aspects of the present disclosure, a handover may implement a legacy serving cell change procedure or an enhanced serving cell change procedure. In either case, signaling from the network to user equipment includes information to enable the user equipment to change or remove an Active Set when undergoing a handover from a cell with two uplink carriers and accordingly two Active Sets, to a cell with one uplink carrier and accordingly one Active Set.