Grant-Free UL Transmission HARQ Buffer Management
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Solution Overview
Problem
In grant-free UL transmission, HARQ control issues lead to delayed or failed data transmission due to occupied HARQ buffers, preventing user equipment from promptly transmitting data even when retransmission control is necessary.
Innovation Solution
User equipment is configured with a configuration information management unit to retain information about divided resources associated with retransmission control processes, allowing it to select and use a resource with an empty buffer for data transmission, thereby facilitating prompt data transmission during retransmission control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If grant-free UL transmission is implemented to enable prompt data transmission, then transmission latency is reduced, but HARQ buffer occupation prevents successful transmission when buffers are occupied
Solution Approach 1:
The grant-free UL resources are divided into multiple divided resources, and HARQ processes are segmented to correspond with these divided resources. This segmentation allows the system to manage HARQ buffers more efficiently by associating each divided resource with specific HARQ process buffers, enabling prompt transmission when buffers are available while maintaining reliability through proper buffer management.
Solution Approach 2:
HARQ process IDs are preliminarily associated with divided resources before transmission occurs. This preliminary association enables the user equipment to determine in advance which HARQ process buffers correspond to available grant-free resources, allowing prompt transmission decisions to be made without waiting for buffer status checks during the transmission moment.
2Reliability
If HARQ control is performed with sequential buffer management, then retransmission reliability is maintained, but transmission efficiency decreases due to buffer occupation delays
Solution Approach 1:
The HARQ control mechanism is segmented by associating different HARQ process IDs with different divided resources. This segmentation allows parallel management of multiple HARQ processes, where each process can independently manage its buffer status and transmission timing, thereby maintaining reliability through structured control while improving overall transmission efficiency through parallel operations.
3Speed
If grant-free resources are allocated without UL grant permission, then transmission speed increases, but resource coordination complexity increases
Solution Approach 1:
The association between HARQ process IDs and divided resources is preliminarily configured and stored in the user equipment. This preliminary configuration eliminates the need for real-time resource coordination during transmission, as the equipment can autonomously determine which HARQ buffers correspond to available grant-free resources based on pre-stored association information, thereby maintaining high transmission speed while reducing coordination complexity.
Data Source
AI summary
User equipment in a radio communication system is provided. The user equipment includes a configuration information management unit configured to retain configuration information in relation to a plurality of divided resources that are capable of transmitting data without receiving data transmission permission from a communication device that is different from the user equipment, the plurality of divided resources each being associated with retransmission control processes, and a transmitter configured to select, from the plurality of divided resources, a divided resource that is associated with a given retransmission control process whose retransmission control buffer is empty, so as to transmit data by using the divided resource.