Cross-Cell Random Access Handover With Timing Advance Feedback
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Solution Overview
Problem
Existing wireless communication systems face challenges in mobility management, particularly in handovers between cells, with L3-based methods exhibiting long delays, high signaling overhead, and significant interruptions, which are not optimized for diverse application scenarios.
Innovation Solution
A method and device utilizing L1/L2-based mobility enhancement techniques, including the use of PDCCH signals for triggering and responding with feedback information blocks to determine timing advance values, ensuring synchronized handovers across cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If L3-based serving cell change is used, then mobility management is achieved, but handover delay increases and signaling overhead increases
Solution Approach 1:
The network pre-configures multiple candidate target cells and their corresponding timing advance values to the UE before handover is needed. When handover is triggered, the UE can immediately switch to a pre-evaluated target cell with pre-known timing parameters, eliminating the need for real-time timing advance negotiation and reducing handover delay
Solution Approach 2:
The handover process is segmented into independent phases: candidate cell evaluation, target cell selection, and actual handover execution. The MAC-CE feedback mechanism segments the timing advance confirmation process, allowing the network to validate timing advance values independently without blocking the overall handover procedure
2Reliability
If L3-based serving cell change is used, then mobility management is achieved, but signaling overhead increases
Solution Approach 1:
The timing advance value confirmation process is extracted from the main RRC handover signaling flow and handled separately through MAC-CE feedback. This separates critical timing parameters from general handover control signaling, reducing the information burden on RRC messages and optimizing signaling efficiency
Solution Approach 2:
The network sends timing advance values as pre-calculated reference data to the UE through MAC-CE messages, copying the essential timing parameters needed for handover without requiring extensive negotiation. This reduces signaling overhead by transmitting only the critical copied parameters rather than full negotiation sequences
3Reliability
If L3-based serving cell change is used, then mobility management is achieved, but interruption time increases
Solution Approach 1:
The UE performs L1/L2 measurements and evaluates candidate target cells in advance, identifying suitable handover targets before actual handover execution. This preliminary evaluation ensures that when handover is triggered, the UE can immediately switch to a pre-validated target cell, minimizing service interruption time
Solution Approach 2:
The MAC-CE feedback mechanism provides real-time confirmation of timing advance value validity, allowing the network to quickly verify handover parameters and trigger handover execution without prolonged negotiation. This feedback loop reduces the decision-making time and accelerates the handover process, minimizing interruption
4Speed
If L1/L2-based mobility enhancement is used, then handover speed increases, but timing advance coordination complexity increases
Solution Approach 1:
The MAC-CE message serves as an intermediary mechanism between the network and UE for timing advance value confirmation. This intermediary layer simplifies the coordination by providing a standardized, dedicated feedback channel that automatically handles timing parameter validation, reducing the complexity of direct L1/L2 timing coordination
Solution Approach 2:
The network autonomously calculates and determines the appropriate timing advance values for candidate target cells based on its own measurements and UE location information. This self-service approach eliminates the need for complex bidirectional negotiation, allowing the network to unilaterally configure timing parameters and reduce coordination complexity
Data Source
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AI summary
The present application discloses a method and device used in a node for wireless communication. A node receives a first PDCCH; the node transmits a first signal, wherein the first PDCCH is used for triggering the transmission of the first signal, and the first signal carries a random access preamble sequence; the node receives a second PDCCH, wherein the second PDCCH is used for responding to the first signal; and the node transmits a first feedback information block; the first signal is associated with a first cell, and the first cell is a cell other than a cell to which the first PDCCH belongs; the second PDCCH is used for determining a target information block, the target information block is used for determining a timing advance value for the first cell, and the first feedback information block is used for indicating whether the target information block is valid. The present application improves handover performance.