Adaptive HARQ Timing Relaxation for Wireless Latency
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Solution Overview
Problem
Current wireless network technologies face challenges in achieving the stringent 3 ms processing latency required for full throughput, especially in scenarios involving multiple network nodes, due to tight HARQ timing constraints, which can limit centralized processing and multipoint transmission/reception.
Innovation Solution
A method for dynamically selecting HARQ relaxation techniques based on estimated latency-related transmission parameters, such as cell load and channel quality, to relax HARQ timing constraints, allowing for adaptable HARQ retransmission round-trip times by disabling retransmissions, skipping sub-frames, or alternating between transport blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fixed HARQ timing constraints are enforced (4TTI feedback delay), then spectral efficiency is improved through full TTI utilization, but network processing latency cannot exceed 3 ms which limits centralized processing and multipoint transmission
Solution Approach 1:
The patent applies dynamics by making the HARQ round-trip time configurable rather than fixed. The network node can dynamically adjust the HARQ RTT parameter based on processing capabilities and scenario requirements, allowing the system to adapt between strict timing (for spectral efficiency) and relaxed timing (for centralized processing). This is implemented through RRC signaling that configures different HARQ RTT values for different uplink subframes or scenarios.
Solution Approach 2:
The patent changes the timing parameter of HARQ operations by introducing configurable HARQ round-trip time values. Instead of the fixed 4TTI feedback delay, the system can now use different HARQ RTT parameters (e.g., 4TTI, 5TTI, 6TTI, or longer) configured via RRC signaling. This parameter change enables centralized processing and multipoint transmission while maintaining spectral efficiency through optimized timing configurations.
2Reliability
If HARQ retransmissions are performed frequently to maintain reliability, then transmission robustness is improved, but processing delay increases which affects latency-sensitive applications
Solution Approach 1:
The patent implements periodic action through configured HARQ retransmission opportunities. Instead of continuous or ad-hoc retransmissions, the system schedules retransmissions at periodic intervals defined by the HARQ RTT parameter. This allows the network to balance reliability (through scheduled retransmissions) and latency (by controlling the periodic interval), particularly benefiting latency-sensitive applications like URLLC.
3Speed
If strict 3 ms processing latency is enforced to achieve full throughput, then network responsiveness is improved, but device complexity increases to meet tight timing constraints
Solution Approach 1:
The patent reduces device complexity by changing the timing parameter from strict 3 ms to configurable longer durations. The network node can set HARQ RTT parameters that provide sufficient processing time for devices, reducing the complexity of meeting tight timing constraints while maintaining network responsiveness through optimized configurations for different service types.
Data Source
AI summary
The present disclosure is directed to a method and apparatus for controlling a Hybrid Automatic Repeat Request, HARQ, retransmission round-trip time for transmission in a wireless network. The method comprises to estimate (S41) one or more latency related transmission parameters and to select (S43) one or more of a plurality of predefined HARQ relaxation techniques based on the estimated one or more latency related transmission parameters. Transmission is scheduled (S44) using the selected one or more HARQ relaxation technique.