Priority-Based Grant-Free Uplink Parts for Selective Retransmission
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing grant-free uplink transmissions, particularly in determining appropriate back-off values and redundancy versions for successful data retransmissions.
Innovation Solution
A wireless transmit/receive unit (WTRU) employs a priority-based approach for grant-free transmissions, where a first part of the transmission includes high-priority acknowledgement information and a second part includes channel quality information, with separate back-off value ranges for successful and retransmission attempts, and uses different redundancy versions for multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single back-off value range is used for all grant-free transmissions, then the system is simple to operate, but retransmission reliability is reduced due to collision probability
Solution Approach 1:
The patent divides the back-off value selection into two distinct segments: a first back-off value range for initial grant-free transmissions and a second back-off value range for retransmissions. This segmentation allows the system to optimize collision avoidance for retransmissions using a larger second range while maintaining simplicity for initial transmissions with the smaller first range, thereby improving retransmission reliability without excessive complexity.
Solution Approach 2:
The patent implements dynamic adaptation by switching between different back-off value ranges based on transmission status. The WTRU dynamically selects from the first range for initial transmissions and from the second range for retransmissions, allowing the system to adapt its collision avoidance strategy according to the specific transmission context and improve overall reliability.
2Speed
If grant-free resources are frequently available, then transmission speed increases, but resource collision probability increases
Solution Approach 1:
The patent applies preliminary action by having the WTRU select and prepare a back-off value from the appropriate range before attempting transmission. For retransmissions, the WTRU preliminarily determines to use the second back-off value range, which is configured to reduce collision probability, thereby preparing the system in advance to handle the increased collision risk associated with frequent grant-free resource availability.
3Reliability
If high-priority information is always retransmitted, then reliability of critical data improves, but resource efficiency decreases due to unnecessary retransmissions
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different parts of the grant-free transmission. The first part containing acknowledgement information is handled with higher priority and more aggressive retransmission using the first back-off range, while the second part containing channel quality information uses the second back-off range. This localized differentiation ensures critical data reliability while optimizing resource efficiency for less critical information.
Data Source
AI summary
A wireless transmit receive unit (WTRU) may send a grant free transmission comprising a first and a second part, each of which may be associated with a priority. The first part's priority may be higher than the second part's priority. The WTRU may select a first back of value from a first range of back off values. The WTRU may determine whether the grant free transmission was successful. If the grant free transmission was not successful, the WTRU may send a retransmission of the grant free transmission, which may include the first part and may not include the second part. The retransmission may select a second back off value from a second range of back off values, which may be a larger than the first range of back off values. The second back off value may indicate the number of grant free resource to skip prior to sending the retransmission.