Flexible TTI Scheduling With Split ACK Timing for Low-Latency HARQ
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Solution Overview
Problem
Existing wireless communication networks face challenges in achieving low latency and efficient data transmission due to limitations in TDD switching and acknowledgment processes, particularly in self-contained subframes.
Innovation Solution
The method involves receiving and transmitting data units in separate transmission time intervals within a subframe, with separate acknowledgments in the uplink control region, allowing for faster processing and reduced latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If data units are transmitted in separate TTIs within a subframe, then processing time is increased and latency is reduced, but the radio interface may become bottlenecked
Solution Approach 1:
The subframe is divided into multiple TTIs (Transmission Time Intervals), with each TTI carrying a specific data unit. This segmentation allows independent processing and acknowledgment of each data unit, enabling the system to reduce latency for individual units while maintaining overall throughput through parallel transmission across multiple TTIs within the same subframe.
2Speed
If separate acknowledgments are provided for each data unit in the uplink control region, then HARQ retransmission speed is improved, but the uplink control region capacity is consumed
Solution Approach 1:
The uplink control region is segmented to provide separate acknowledgment channels for different data units. Each data unit transmitted in a specific TTI receives a dedicated acknowledgment signal in the uplink control region, enabling independent HARQ processing and rapid retransmission decisions without interfering with other data units' control signals.
Solution Approach 2:
The acknowledgment signals are prepared and transmitted in advance within the uplink control region before the next data transmission cycle begins. This preliminary acknowledgment action allows the receiver to immediately prepare for potential retransmissions, reducing the overall HARQ round-trip time and enabling faster retransmission operations.
3Adaptability or versatility
If self-contained subframes are used for TDD switching, then time division duplexing flexibility is improved, but latency for individual data units increases
Solution Approach 1:
The self-contained subframe is segmented into multiple TTIs, each capable of independent data transmission and acknowledgment. This segmentation allows the system to maintain the flexibility of TDD switching at the subframe level while reducing latency at the data unit level by enabling parallel processing and immediate acknowledgment within the same subframe, rather than waiting for the entire subframe to complete.
Data Source
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AI summary
A method for wireless communication is described. The method comprises receiving, within a subframe, a downlink control region scheduling at least a first data unit to be received in a slot, wherein the subframe comprises at least two transmission time intervals, TTIs, and wherein each slot comprises the downlink control region, a data region, and an uplink control region; receiving the first data unit in a first TTI of the data region; receiving a second data unit in a second TTI of the data region; separately acknowledging receipt of the first and second data units, wherein the first data unit is acknowledged in the uplink control region of the slot; and transmitting acknowledgements/negative acknowledgements, ACKs, NACKs, for the first and second data units in different slots. Further, a corresponding apparatus and computer program are described.