Uplink Synchronization Without RAR in Random Access Completion
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Solution Overview
Problem
Existing technologies lack a method for a terminal device to determine the completion of a random access process when a Random Access Response (RAR) is not required.
Innovation Solution
A method and apparatus for uplink synchronization that allows a terminal device to determine the completion of a random access process based on predefined conditions, such as transmission of a preamble using specific information, including timers and network indications, to establish UL synchronization with a candidate cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal device waits for RAR to determine random access completion, then the reliability of completion determination is improved, but the time loss increases and communication efficiency decreases
Solution Approach 1:
The patent extracts the essential completion determination function from the RAR-dependent process. By defining completion based on preamble transmission conditions (first condition) rather than RAR reception, the solution removes the time-consuming RAR waiting step while maintaining reliable completion determination through alternative criteria.
Solution Approach 2:
The patent applies preliminary action by establishing completion criteria before the random access process executes. The first condition (related to preamble transmission using first information) is predefined, allowing the terminal to determine completion proactively without passively waiting for RAR, thus reducing time loss while maintaining reliability.
2Reliability
If the terminal device uses traditional RAR-based completion determination, then the reliability is maintained, but the communication efficiency and productivity are reduced
Solution Approach 1:
The patent extracts the completion determination function from the RAR-based workflow. By using preamble transmission conditions (first condition) as the completion criterion, the solution eliminates the inefficient RAR waiting step while maintaining reliable completion determination, thereby improving communication efficiency and productivity.
Solution Approach 2:
The patent changes the parameter used for completion determination from RAR reception status to preamble transmission status. This parameter change fundamentally alters the completion determination mechanism, enabling faster and more efficient communication while maintaining reliability through the first condition's predefined criteria.
3Loss of time
If the terminal device implements L1/L2-triggered mobility without RAR-based completion determination, then the latency is reduced, but the complexity of completion determination increases
Solution Approach 1:
The patent applies preliminary action by predefining the first condition (related to preamble transmission using first information) before the random access process executes. This predefined completion criterion simplifies the determination logic during L1/L2-triggered mobility, reducing latency while avoiding increased complexity through clear, advance-established rules.
Solution Approach 2:
The patent extracts the completion determination function from the complex RAR-based process. By using the first condition (preamble transmission status) as the completion criterion, the solution simplifies the determination logic for L1/L2-triggered mobility, reducing latency without introducing complexity, as the criterion is straightforward and pre-established.
Data Source
AI summary
Provided in the embodiments of the application is an uplink synchronization method, the method includes that: when a first condition is met, it is determined that a first random access process is completed, wherein the first random access process is used for establishing uplink synchronization between a terminal device and a first candidate cell, and the first condition is related to indicating that an underlying layer of the terminal device uses a first information transmission preamble.