Low Latency Preemption Using Null Tones in Wi-Fi
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Solution Overview
Problem
Current IEEE 802.11 networks face challenges in supporting low-latency applications during high throughput transmissions, as they struggle to reconcile long TXOPs for high throughput traffic with the need for reduced latency, leading to reduced channel efficiency and increased latency for low-latency applications.
Innovation Solution
The implementation of a low latency preemption system using null tones or dedicated resource units (RUs) for suspend request feedback, allowing for preemptive transmission opportunities during high throughput traffic, enabling efficient low-latency data transmission without significantly impacting high throughput performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If long TXOPs are used for high throughput traffic, then channel efficiency is improved, but latency increases for low-latency applications
Solution Approach 1:
The patent segments the transmission opportunity (TXOP) into multiple smaller transmission units by introducing suspension points where low-latency traffic can be inserted. This allows the high throughput traffic to be divided into segments separated by low-latency transmission opportunities, thereby maintaining channel efficiency while reducing latency for time-sensitive applications.
Solution Approach 2:
The patent establishes predetermined suspension points and feedback mechanisms in advance during the TXOP structure design. These pre-planned interruption points allow low-latency traffic to be accommodated without ad-hoc negotiations, enabling preliminary preparation for latency-critical transmissions while maintaining overall channel efficiency.
2Loss of time
If TXOP limit is reduced to reduce latency, then low-latency application performance is improved, but overall channel efficiency decreases
Solution Approach 1:
The patent implements dynamic TXOP management where the transmission opportunity structure can be flexibly adjusted based on traffic conditions. The system can dynamically insert suspension points and extend TXOPs when low-latency traffic is absent, while providing guaranteed interruption points when needed, thereby adapting to varying latency requirements without permanently limiting channel efficiency.
Solution Approach 2:
The patent creates a multi-functional TXOP structure that can serve both high throughput applications and low-latency applications within the same transmission framework. The same TXOP mechanism supports bulk data transfers while also providing guaranteed latency performance through suspension points, making the system universally applicable to diverse traffic types without sacrificing overall efficiency.
3Loss of time
If preemption opportunities are added for low-latency traffic, then latency is reduced, but system complexity increases
Solution Approach 1:
The patent introduces a feedback mechanism as an intermediary between the transmitter and receiver that manages preemption requests. This feedback channel carries suspension requests and acknowledgments, allowing low-latency traffic to be accommodated through a standardized mediation process rather than requiring complex direct negotiation between multiple devices, thereby reducing overall system complexity.
Solution Approach 2:
The patent implements a feedback-based preemption control system where the receiver acknowledges suspension requests and the transmitter confirms resumption points. This feedback mechanism provides structured communication for preemption management, reducing the need for complex signaling protocols and simplifying the preemption process through clear request-acknowledge-confirm exchanges.
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AI summary
This disclosure describes systems, methods, and devices related to low latency preemption. A device may establish time gaps between consecutive physical layer (PHY) convergence protocol data units (PPDUs) to facilitate preemption opportunity for low latency (LL) transmission. The device may detect a suspend/resource request (SR) transmitted over predefined null tones, wherein the SR is received from a station device (STA). The device may determine if a current transmit opportunity (TXOP) is preemptable and communicate this status through a control frame. The device may set a suspend request (SR) feedback report support subfield within an ultra high reliability (UHR) capabilities element based on a capability to support the SR feedback report.