Candidate Cell Random Access for Low-Delay L1/L2 Mobility
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Solution Overview
Problem
Existing random access procedures in wireless communication networks, particularly during L1/L2 inter-cell mobility, result in prolonged delays and increased overhead due to layer 3 reconfigurations, leading to longer interruptions during serving cell changes.
Innovation Solution
A mechanism for acquiring timing advance (TA) of candidate cells using PDCCH ordered RACH, allowing completion determination of random access procedures on candidate cells through transmission of preambles, PDCCH transmissions, or reception of random access responses, thereby enabling L1/L2 mobility with reduced delays and overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If layer 3 reconfiguration is used for serving cell changes, then mobility management is achieved, but delays and overhead are prolonged
Solution Approach 1:
The patent applies preliminary action by performing random access procedures on candidate cells before the actual serving cell switch occurs. The terminal acquires timing advance information and completes random access on candidate cells in advance, so that when the serving cell change is triggered, the transition can happen immediately without waiting for layer 3 reconfiguration, thus reducing mobility delays
Solution Approach 2:
The patent segments the mobility management process into two parts: (1) preliminary random access and timing advance acquisition on candidate cells, and (2) actual serving cell switching. This segmentation allows the time-consuming random access procedure to be decoupled from the critical serving cell change operation, reducing the impact on service continuity
2Reliability
If layer 3 reconfiguration is performed for serving cell changes, then cell switching is completed, but overhead and interruption times are increased
Solution Approach 1:
The terminal performs preliminary random access procedures and acquires timing advance information for candidate cells before the serving cell change is actually triggered. This preliminary preparation eliminates the need for complex layer 3 reconfiguration procedures during the actual cell switch, reducing both overhead signaling and interruption time
Solution Approach 2:
The terminal autonomously manages timing advance information for candidate cells through self-service random access procedures. By maintaining its own timing advance records for candidate cells, the terminal reduces dependency on network-controlled layer 3 reconfiguration, thereby reducing signaling overhead and simplifying the cell switching process
Data Source
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AI summary
Embodiments of this disclosure provide a random access method and apparatus. The method includes: when a terminal equipment transmits a random access preamble on a candidate cell, and/or when the terminal equipment receives a PDCCH transmission in a search space or a control resource set (coreset) related to the candidate cell, determining that a random access procedure on the candidate cell is completed; or, when the terminal equipment receives a random access response, determining that a random access procedure on the candidate cell is completed.