HARQ Buffer MAC PDU Retrieval for De-Prioritized Uplink Grants
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Solution Overview
Problem
The existing 5G New Radio (NR) communication system requires improved methods for transmitting Medium Access Control (MAC) Protocol Data Units (PDUs) using the Hybrid Automatic Repeat reQuest (HARQ) mechanism, particularly in cases of uplink grant prioritization and overlapping physical channels.
Innovation Solution
A method and device for transmitting MAC PDUs that involve identifying a HARQ process associated with an uplink grant and obtaining a MAC PDU from a HARQ buffer based on specific conditions, including prioritization and overlapping of physical uplink shared channels, and instructing a retransmission when necessary, with a HARQ entity managing the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a HARQ mechanism is applied in 5G NR system with priority-based prioritization for configured grants, then data transmission reliability is improved through autonomous retransmissions, but device complexity increases due to additional conditions for obtaining MAC PDUs from HARQ buffer
Solution Approach 1:
The system performs preliminary actions by maintaining MAC PDUs in the HARQ buffer before they are needed for retransmission. When a configured grant is de-prioritized or PUSCH durations overlap, the MAC PDU is already prepared in the buffer, enabling autonomous retransmission without requiring complex real-time decisions at the moment of transmission failure.
Solution Approach 2:
The HARQ entity autonomously determines whether to obtain a MAC PDU from the HARQ buffer based on pre-defined conditions (de-prioritized configured grants, overlapping PUSCH durations). This self-service mechanism allows the system to handle retransmissions automatically without external intervention, improving reliability while managing complexity through rule-based automation.
2Productivity
If autonomous retransmissions are enabled for de-prioritized configured grants, then productivity is improved through efficient resource utilization, but loss of time increases due to additional processing conditions for MAC PDU retrieval
Solution Approach 1:
MAC PDUs are pre-obtained and stored in the HARQ buffer before retransmission is needed. This preliminary action eliminates the need for time-consuming MAC PDU generation at the moment of retransmission, allowing the system to quickly react to de-prioritized grants or overlapping PUSCH durations while maintaining efficient resource utilization.
3Reliability
If MAC PDU is obtained from HARQ buffer for overlapping PUSCH durations, then reliability is improved through successful retransmission handling, but device complexity increases due to overlapping duration detection and management
Solution Approach 1:
The system implements a feedback mechanism where the HARQ entity monitors PUSCH duration overlaps and triggers appropriate actions (obtaining MAC PDU from buffer, delivering to HARQ process). This feedback loop ensures reliable handling of overlapping transmissions while managing complexity through structured monitoring and response protocols.
Solution Approach 2:
The HARQ entity autonomously detects overlapping PUSCH durations and self-manages the retransmission process by retrieving MAC PDUs from the buffer. This self-service approach handles overlapping transmission scenarios reliably without requiring external coordination, maintaining transmission success rates while containing complexity within the HARQ entity.
Data Source
AI summary
A method and device for transmitting a medium access control (MAC) protocol data unit (PDU) is provided. The method includes: identifying, by a hybrid automatic repeat request (HARQ) entity, for an uplink grant, a HARQ process associated with the uplink grant; and obtaining, by the HARQ entity, a MAC PDU to transmit from a HARQ buffer of the identified HARQ process when a particular condition(s) is satisfied. The condition may be that a MAC entity of the HARQ entity is configured with priority based prioritization, the uplink grant is a configured grant, and a previous uplink grant for the HARQ process was de-prioritized and the MAC PDU had already been obtained for the HARQ process.