L1/L2 Cell Mobility Signaling Without Random Access
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Solution Overview
Problem
Current methods for cell change or addition in telecommunication networks involve layer 3 (L3) measurements and radio resource control (RRC) signaling, leading to longer latency, higher overhead, and longer interruption times due to complete layer 2 (L2) and layer 1 (L1) resets during mobility changes.
Innovation Solution
Implementing lower-layer signaling (L1/L2) to enable data transmission on a target cell while skipping the random access procedure, allowing for the determination of a timing advance value to facilitate seamless cell changes or additions without the need for a random access procedure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If L3 measurements and RRC signaling are used for cell change, then reliability is improved, but latency and interruption time increase
Solution Approach 1:
The patent segments the mobility procedure into two parts: L1/L2 rapid execution for physical cell change, and L3 RRC signaling for configuration confirmation. This allows the time-critical cell switch to occur rapidly at lower layers while higher layers catch up, resolving the contradiction between reliability (L3 confirmation) and latency (L1/L2 speed).
Solution Approach 2:
The patent performs preliminary L1/L2 cell change actions before L3 RRC signaling completes. The terminal device switches cells at L1/L2 level first, then waits for L3 confirmation, enabling mobility to start immediately rather than waiting for complete L3 procedure, thus reducing latency while maintaining reliability through subsequent L3 confirmation.
2Reliability
If complete L2 and L1 resets are performed during cell change, then reliability is improved, but overhead and interruption time increase
Solution Approach 1:
The patent extracts the essential cell switching function from the complete L1/L2 reset procedure. Instead of performing full resets, the invention applies timing advance values and uplink configuration from the target cell to enable direct cell switch, removing unnecessary reset operations that contribute to overhead and complexity.
Solution Approach 2:
The patent changes the parameters of the cell change procedure by using timing advance values and uplink configurations directly from the target cell without complete resets. This parameter-based approach reduces signaling overhead while maintaining the necessary reliability for cell change operations.
3Measurement precision
If random access procedure is performed for cell change, then timing synchronization is improved, but latency and interruption time increase
Solution Approach 1:
The patent performs preliminary timing synchronization by applying timing advance values from the target cell before data transmission begins. This preliminary timing alignment eliminates the need for a complete random access procedure, achieving both timing synchronization and reduced latency.
Solution Approach 2:
The patent skips the complete random access procedure by directly applying timing advance values and uplink configurations. This skipping of unnecessary steps achieves timing synchronization through alternative means while dramatically reducing the latency and interruption time associated with full random access.
Data Source
AI summary
Embodiments of the present disclosure relate to methods, devices and computer readable media for communication. A terminal device receives, from a first network device, a lower-layer signaling indicating that a data transmission is to be enabled on a cell of a second network device. If a random access procedure is determined to be skipped for the data transmission, the terminal device determines a timing advance value for a timing advance group that comprises the cell, and enables the data transmission based on the timing advance value. In this way, latency for a L1/L2 based mobility procedure may be reduced.