Handover Interruption Reduction via Dual-Active Uplink
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Solution Overview
Problem
Legacy handover operations in LTE systems experience interruptions due to the need for user equipment (UE) to drop connections from source cells and re-establish them with target cells, leading to potential bottlenecks in AGC, timing, beamforming, and numerology compatibility issues during simultaneous communication with multiple cells.
Innovation Solution
Implementing a per-UE capability indicator to determine if a UE can support simultaneous transmission/reception with multiple cells, using Boolean variables and separate information elements to assess intra-frequency, inter-frequency, intra-band, and inter-band communications, as well as FR1 and FR2 capabilities, to reduce handover interruption times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE drops connection from source cell and re-establishes with target cell during handover, then handover can be completed, but interruption time increases and connectivity is degraded
Solution Approach 1:
The network configures the UE with uplink synchronization parameters and timing advance values for the target cell before the handover is executed. This preliminary configuration allows the UE to immediately establish uplink communication with the target cell without interruption, as the synchronization information is already available prior to the handover command.
Solution Approach 2:
The patent enables continuous data transmission during handover by maintaining the UE's connection state and configuring dual-active uplink resources. The UE can simultaneously transmit data to both source and target cells or switch seamlessly without breaking the data flow, ensuring continuous useful action during the handover process.
2Loss of time
If UE simultaneously communicates with multiple cells during handover, then interruption time is reduced, but device complexity and resource requirements increase
Solution Approach 1:
The patent segments the simultaneous communication capability into separate configurable parameters for different frequency bands and cell types. The network can selectively enable dual-active uplink for specific frequency combinations and cell configurations, reducing the overall complexity burden on the UE while maintaining the benefit where needed.
Solution Approach 2:
The patent applies dual-active uplink configuration locally to specific UE capabilities and network scenarios rather than requiring all UEs to support full simultaneous multi-cell communication. The network assesses individual UE capabilities and configures appropriate handover parameters, allowing complex functionality only where required.
3Productivity
If UE supports simultaneous transmission/reception with different cells, then handover performance is improved, but AGC, timing, and beamforming bottlenecks increase
Solution Approach 1:
The network provides AGC gain values, timing advance parameters, and beamforming configuration information to the UE before the handover is executed. This preliminary provision of signal processing parameters eliminates the need for complex real-time adjustments during simultaneous communication, reducing the processing bottleneck while maintaining high handover speed.
4Measurement precision
If separate capability indicators are used for intra-frequency, inter-frequency, intra-band, and inter-band communications, then capability assessment precision is improved, but message overhead and processing complexity increase
Solution Approach 1:
The capability indication is segmented into separate Boolean variables for different frequency and band scenarios (intra-frequency, inter-frequency, intra-band, inter-band). This segmentation allows precise capability assessment for each scenario while enabling the network to request only the relevant capability indicators needed for the specific handover situation, reducing unnecessary overhead.
Solution Approach 2:
The patent creates a universal capability indication framework where a single set of structured messages can convey multiple capability aspects simultaneously. The same message structure serves multiple purposes by encoding different capability dimensions, reducing the need for separate dedicated messages for each capability type.
Data Source
AI summary
Methods, systems, and storage media described herein may have the complexity to support simultaneous communications (e.g., transmission/reception to/from) with two or more cells. Therefore, before configuring a handover, the network needs to know if these methods, systems, and storage media can support simultaneous communication with multiple cells or not. Among other things, these methods, systems, and storage media can reduce the interruption time during handovers for when these methods, systems, and storage media are capable of such simultaneous communication.