Random Access Contention Resolution Timer Adjustment in Wireless Terminals
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Solution Overview
Problem
In non-terrestrial networks, the increased round-trip time between terminal devices and network devices leads to unnecessary PDCCH monitoring by terminal devices, resulting in frequent random access initiations and increased random access delay due to premature expiration of the random access contention resolution timer.
Innovation Solution
The random access contention resolution timer is adjusted by introducing a time offset for its start time, allowing the terminal device to reconsider contention resolution success based on the reception status of Msg4 after Msg3 retransmission, rather than immediately failing upon timer expiration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a time offset is introduced for the start time of the random access contention resolution timer in NTN systems to avoid unnecessary PDCCH monitoring, then the terminal device can reduce unnecessary monitoring, but the timer may expire prematurely before retransmission, causing false contention resolution failure determination
Solution Approach 1:
The patent applies dynamics by making the timer restartable rather than fixed. When a PDCCH for Msg3 retransmission is detected, the timer is restarted, allowing it to adapt to the extended timing requirements of NTN systems with large RTT. This dynamic adjustment prevents premature expiration while maintaining the benefit of reduced monitoring.
Solution Approach 2:
The patent implements feedback by having the terminal device monitor PDCCH for Msg3 retransmission and use this feedback to restart the timer. This feedback mechanism ensures the timer reflects actual communication status, preventing false failure determinations while maintaining energy efficiency.
2Adaptability or versatility
If the random access contention resolution timer is restarted based on Msg3 retransmission, then the timer can accommodate large RTT in NTN systems, but the timer may still expire before the retransmission is complete, causing premature failure determination
Solution Approach 1:
The patent applies preliminary action by having the terminal device prepare for timer restart in advance. When PDCCH for retransmission is detected, the timer is restarted before the retransmission actually occurs, ensuring the timer is already positioned to cover the extended timing requirements without causing premature expiration.
Solution Approach 2:
The patent ensures continuity of useful action by making the timer restart continuously as long as retransmission is needed. This continuous adjustment maintains the timer's alignment with actual communication needs, preventing both premature expiration and unnecessary delay.
3Ease of operation
If the terminal device immediately determines contention resolution failure upon timer expiration, then the decision process is simple and fast, but in NTN systems with large RTT, this causes frequent false failures and increased random access delay
Solution Approach 1:
The patent transforms the static failure determination into a dynamic process. Instead of immediate failure upon expiration, the system now considers whether the timer was restarted due to detected PDCCH for retransmission. This dynamic evaluation maintains simplicity while significantly improving reliability in NTN systems.
Solution Approach 2:
The patent changes the parameter of timer behavior from fixed to restartable. By modifying how the timer operates (adding restart capability based on PDCCH detection), the system can accommodate large RTT while maintaining a relatively simple determination process that checks both timer expiration and restart status.
Data Source
AI summary
Disclosed are a wireless communication method and a terminal device. The method includes: in a case that a random access contention resolution timer expires and a physical downlink control channel PDCCH for scheduling retransmission of a message Msg3 is not received before the random access contention resolution timer expires, considering, by a terminal device, that contention resolution does not succeed; and/or, in a case that the random access contention resolution timer expires and the PDCCH for scheduling the retransmission of the Msg3 is received before the random access contention resolution timer expires, skipping, by the terminal device, considering that contention resolution fails.