Terminal Fallback from Two-Step to Four-Step Random Access
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Solution Overview
Problem
The two-step random access procedure in wireless communication systems often fails to establish connections due to unfavorable wireless environments, leading to delayed connection establishment and increased time requirements, as the radio resources and transmission parameters are not dynamically allocated, causing the base station to fail in receiving the message A, resulting in repeated attempts until the environment improves.
Innovation Solution
Implementing a fallback mechanism where the terminal apparatus transitions from a two-step random access procedure to a four-step random access procedure when a predetermined number of unsuccessful attempts or elapsed time exceeds a threshold, allowing for dynamic allocation of resources and improved connection establishment by switching to four-step RACH when two-step RACH is unconducive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If two-step random access procedure is used, then connection establishment time is reduced, but connection reliability deteriorates when wireless environment is unfavorable
Solution Approach 1:
The patent implements dynamic switching between two-step RACH and four-step RACH based on real-time wireless environment assessment. The terminal apparatus evaluates channel conditions and randomly selects between the two procedures, allowing the system to adapt dynamically to changing network conditions and maintain both speed and reliability.
Solution Approach 2:
The patent changes the random access procedure parameter from fixed two-step to variable selection between two-step and four-step procedures. By introducing randomness and environmental-based selection, the system can adjust the procedure type according to current wireless conditions, resolving the contradiction between speed and reliability.
2Loss of time
If two-step random access procedure is used, then random access time is reduced, but adaptability to wireless environment deteriorates
Solution Approach 1:
The system dynamically adapts the random access procedure based on real-time wireless environment assessment. The terminal apparatus evaluates channel conditions and selects between two-step and four-step RACH procedures, enabling the system to adjust to varying network conditions while maintaining fast access times.
Solution Approach 2:
The patent introduces variability in the random access procedure selection by allowing the terminal to choose between different procedure types based on environmental conditions. This parameter change enables the system to maintain both speed and adaptability to different wireless scenarios.
3Device complexity
If fixed radio resources are allocated for two-step RACH, then procedure simplicity is maintained, but connection establishment reliability decreases in unfavorable conditions
Solution Approach 1:
The patent introduces dynamic procedure selection where the terminal apparatus evaluates wireless conditions and randomly selects between two-step and four-step RACH procedures. This dynamic approach maintains simplicity in favorable conditions while providing enhanced reliability in unfavorable conditions through automatic procedure switching.
Solution Approach 2:
The terminal apparatus performs preliminary evaluation of wireless environment conditions before initiating the random access procedure. By assessing channel conditions in advance and selecting the appropriate procedure type beforehand, the system prepares for potential reliability issues and mitigates them through proactive procedure selection.
Data Source
AI summary
A terminal apparatus, which executes a two-step random access procedure or a four-step random access procedure to establish a connection with a base station apparatus, executes control such that, in a case where a first message of the two-step random access procedure including a preamble and predetermined information for connection establishment is transmitted and a number of unsuccessful attempts to receive the first message by the base station apparatus exceeds a predetermined number, the terminal apparatus transmits a second message to be transmitted from the terminal apparatus to the base station apparatus in the four-step random access procedure.