Layer 2 Mobility via Dual PDCCH Orders
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Solution Overview
Problem
Current mobile communication systems face challenges in achieving seamless layer 2 mobility with minimal interruption time, especially when a user equipment (UE) transitions between cells in 5G communication systems.
Innovation Solution
The proposed solution involves a method where a UE transmits UECapabilityInformation to a base station, receives a RRCReconfiguration message, and performs layer 2 mobility by transmitting a preamble to the base station based on a PDCCH order, allowing for UE-specific search space configuration and mobility group management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If L3 measurements and RRC signalling triggered Reconfiguration with Sync are used for serving cell change, then complete L2 and L1 resets are performed ensuring reliable cell transition, but latency and interruption time increase significantly
Solution Approach 1:
The patent segments the mobility procedure into two distinct types: Type 1 PDCCH order for beam-level switching within a cell without L2 reset, and Type 2 PDCCH order for cell-level switching with L2 reset. This segmentation allows the system to choose the appropriate granularity of reset based on the specific mobility scenario, reducing unnecessary interruption time while maintaining reliability when needed.
Solution Approach 2:
The patent introduces dynamic mobility mechanisms where the UE can switch between different PDCCH orders and mobility types based on current radio conditions and network configuration. The system dynamically adjusts the level of reset (L1 only vs L1+L2) based on whether the UE is performing beam switching or cell reselection, optimizing the balance between reliability and interruption time.
2Speed
If beamforming and massive MIMO are used to increase propagation distance in 5G mmW systems, then signal coverage is improved, but system complexity increases
Solution Approach 1:
The patent segments the beam management complexity by introducing separate PDCCH order types: Type 1 for beam switching (lower complexity) and Type 2 for cell reselection (higher complexity). This allows the system to handle beamforming operations at a finer granularity, managing complexity by treating beam-level and cell-level operations separately rather than as a monolithic complex system.
Solution Approach 2:
The patent applies partial action by implementing L1-only resets for beam switching scenarios where full L2 reset is not necessary. This partial reset approach reduces the complexity overhead while maintaining sufficient signal coverage through beamforming, avoiding the excessive complexity of complete L2/L1 resets for every beam switch.
3Loss of time
If UE specific search space configuration and mobility group management are implemented for layer 2 mobility, then interruption time is reduced, but configuration complexity increases
Solution Approach 1:
The patent segments the search space configuration into UE-specific search spaces for Type 1 PDCCH order monitoring and common search spaces for Type 2 PDCCH order monitoring. This segmentation allows the UE to monitor different search spaces based on the mobility type, reducing interruption time by having pre-configured monitoring resources ready, while managing configuration complexity through structured organization of search space parameters.
Solution Approach 2:
The patent implements preliminary action by pre-configuring UE-specific search spaces and mobility group identifiers before mobility events occur. The RRCReconfiguration message预先 configures the UE with Type1-PDCCH-OrderSearchSpace and Type2-PDCCH-OrderSearchSpace, so that when mobility is needed, the UE can immediately switch to the appropriate search space without configuration delays, reducing interruption time.
Data Source
AI summary
A method and apparatus for layer 2 mobility is provided. Method for lower layer mobility includes transmitting the UECapabilityInformation to the base station, receiving a RRCReconfigruation from the base station, receiving a PDCCH order from the base station and transmitting a preamble to the base station based on the PDCCH order. The RRCReconfiguration includes a UE specific search space configuration information for type1 PDCCH order monitoring and a first RNTI for type1 PDCCH order monitoring and common search space identifier for type2 PDCCH order monitoring and a second RNTI for type2 PDCCH order monitoring. The RRCReconfiguration includes one or more inner RRCReconfiguration and associated mobility group identifier.