Deadline-Based HARQ Retransmission for Timely Uplink Packets
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in managing packet delay budgets for uplink transmissions, leading to resource waste due to obsolete packet transmissions and retransmissions, particularly in high-reliability and low-latency applications like extended reality (XR) traffic, where packets not received within a defined deadline become obsolete.
Innovation Solution
Configuring a packet delay budget for logical channels at the user equipment (UE) based on the generation of data, allowing the UE to skip transmissions and retransmissions after the deadline is exceeded, thereby optimizing resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE continues retransmission procedures for uplink messages beyond the packet delay budget, then the reliability of packet delivery is improved, but resource waste increases due to obsolete packet transmissions
Solution Approach 1:
The UE performs preliminary checking of the packet delay budget before each retransmission. The packet delay budget timer is started when the first uplink message is transmitted, and the UE checks whether the current time exceeds the packet delay budget before transmitting retransmission messages. This preliminary action prevents wasteful retransmissions of obsolete packets while maintaining reliable delivery within the valid time window.
2Reliability
If the UE transmits all scheduled uplink message instances, then the completeness of data transmission is improved, but the time efficiency deteriorates due to delayed resource allocation
Solution Approach 1:
The retransmission procedure is made dynamic by continuously monitoring the packet delay budget timer. The UE dynamically adjusts the retransmission behavior based on the remaining time budget - transmitting retransmission messages when time permits and stopping when the budget is exhausted. This dynamic approach optimizes both transmission completeness and time efficiency by adapting to real-time deadline constraints.
3Speed
If the UE monitors for retransmission opportunities throughout the packet delay budget period, then the responsiveness to transmission opportunities is improved, but the device complexity increases due to continuous monitoring requirements
Solution Approach 1:
Instead of continuous monitoring, the UE performs periodic checks at specific retransmission opportunities defined by the network scheduler. The UE monitors for downlink assignments indicating retransmission opportunities and checks the packet delay budget at these discrete moments. This periodic monitoring approach maintains responsiveness to transmission opportunities while significantly reducing device complexity compared to continuous monitoring.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive control signaling identifying a packet delay budget for a logical channel for a UE. The UE may transmit one or more instances of an uplink message associated with the same hybrid automatic repeat request (HARQ) process identification, where the transmission of the first instance of the one or more instances of the uplink message is associated with the start of the packet delay budget for the logical channel. The one or more instances may be associated with a retransmission procedure for the uplink message. The UE may end the retransmission procedure associated with the uplink message based on the elapsed buffering time of the uplink message exceeding the packet delay budget.