HARQ Subpacket Rate Adaptation for Bundled Acknowledgments
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Solution Overview
Problem
In wireless communication networks, particularly over TDD channels, bundled HARQ acknowledgments can lead to unnecessary retransmissions of properly received HARQ subpackets due to asymmetric time slots, resulting in inefficiency.
Innovation Solution
The RAN adjusts transmission rates based on signal quality and acknowledgment bundling, transmitting HARQ subpackets at a lower rate in slots with bundled acknowledgments to reduce retransmissions, while maintaining nominal rates in slots without bundling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bundled HARQ acknowledgments are used to accommodate asymmetric time slots in TDD channels, then the reverse-direction time slot constraint is satisfied, but unnecessary retransmissions occur because all subpackets in a bundle must be retransmitted when one is not properly received
Solution Approach 1:
The patent segments the HARQ acknowledgment process by introducing individual acknowledgment bits for each subpacket within a bundle. Instead of a single bundled acknowledgment, each subpacket receives its own acknowledgment bit, allowing independent tracking of reception status. This segmentation enables selective retransmission of only failed subpackets rather than requiring retransmission of all subpackets in the bundle, thereby resolving the contradiction between accommodating asymmetric time slots and avoiding unnecessary retransmissions.
2Productivity
If HARQ subpackets are transmitted at nominal transmission rate in all data slots, then data throughput is maximized, but packet error rate increases in slots subject to bundled acknowledgments
Solution Approach 1:
The patent dynamically adjusts the transmission rate of HARQ subpackets based on the acknowledgment bundling configuration. In data slots subject to bundled acknowledgments, the transmission rate is reduced to ensure more reliable packet reception, while nominal transmission rate is maintained in slots without bundling. This dynamic rate adaptation allows the system to optimize between throughput and reliability depending on the specific time slot configuration, resolving the contradiction between maximizing data throughput and minimizing packet error rate.
Data Source
AI summary
It may be determined that a HARQ transmission schedule from a RAN to a WCD includes HARQ acknowledgment bundling. An indication of signal quality as measured by the WCD may be received by the RAN. The indicated signal quality may be associated with a first transmission rate. The RAN may determine a first set of one or more data slots of the HARQ transmission schedule for which the WCD bundles HARQ acknowledgments. In response to this determination, one or more HARQ subpackets may be transmitted to the WCD in the first set of one or more data slots. The one or more HARQ subpackets may be transmitted at a second transmission rate that is less than the first transmission rate.