Sidelink HARQ-ACK Configuration for Latency and Reliability Trade-offs
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing sidelink transmissions in congested situations, particularly in determining whether to enable or disable Hybrid Automatic Repeat Request (HARQ) acknowledgments (ACK) for sidelink control information and data, which affects the reliability and latency of sidelink communications.
Innovation Solution
The proposed solution involves configuring sidelink transmissions to ensure that either all sidelink data and control elements use the same enabling or disabling HARQ-ACK behavior within a single transport block, allowing for consistent HARQ-ACK management and reducing unnecessary retransmissions by indicating HARQ-ACK behavior based on pre-configuration or content-specific considerations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ-ACK is enabled for all sidelink transmissions, then reliability is improved, but latency increases due to unnecessary retransmissions
Solution Approach 1:
The patent applies local quality by enabling HARQ-ACK selectively for specific sidelink transmissions rather than uniformly for all transmissions. The network device configures different HARQ-ACK behaviors for different sidelink logical channels or transmission types based on their specific reliability requirements, allowing high-reliability traffic to use HARQ-ACK while low-reliability traffic skips it to reduce latency.
Solution Approach 2:
The patent implements dynamics by making the HARQ-ACK configuration flexible and adaptable. The network device can dynamically adjust whether HARQ-ACK is enabled or disabled for sidelink transmissions based on current network conditions, traffic types, and reliability requirements. This dynamic configuration allows the system to optimize between reliability and latency in real-time.
2Adaptability or versatility
If HARQ-ACK behavior is configured per sidelink logical channel, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the sidelink communication into multiple logical channels, each with its own HARQ-ACK configuration. Instead of managing one complex global configuration, the system segments the configuration management into channel-specific settings, making it easier to handle different traffic types with different reliability requirements independently.
Solution Approach 2:
The patent implements universality by creating a standardized configuration mechanism that can be applied across multiple sidelink logical channels. The network device uses a universal configuration approach where the same set of rules and parameters can be replicated and applied to different channels, reducing the overall complexity compared to customizing each channel individually.
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AI summary
A method and apparatus are disclosed from the perspective of a first device for performing sidelink communication. In one embodiment, the first device includes a MAC CE in a MAC PDU, wherein if the MAC PDU comprises the MAC CE without data, SL HARQ feedback is disabled for the MAC PDU (1005). The first device further includes sidelink data associated with a first sidelink logical channel in the MAC PDU, wherein the first sidelink logical channel is configured to enable sidelink HARQ feedback (1010). The first device also sets or indicates enable SL HARQ feedback for the MAC PDU in a SCI, wherein the SCI schedules a sidelink transmission delivering the MAC PDU (1015). Furthermore, the first device transmits the SCI and performs the sidelink transmission to a second device (1020).