TXOP Preemption for Low Latency Wi-Fi Devices
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Solution Overview
Problem
Current Wi-Fi networks face challenges in reducing latency for low latency applications, especially when channels are occupied by long TXOP data transmissions, leading to increased delays and unreliable communications, which are critical gaps in existing Wi-Fi standards like 802.11be and targets for the next generation Wi-Fi standard, 802.11uhr (Wi-Fi 8).
Innovation Solution
The enhanced Low Latency (LL) system addresses this by segmenting large Physical Protocol Data Units (PPDUs) into smaller units with timed gaps and allowing preemption requests during these gaps, using a concise control frame for channel access, enabling efficient data transmission and minimizing collisions in crowded environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If long TXOP data transmissions occupy the wireless channel, then high throughput is achieved, but latency increases and low latency applications suffer from increased delays
Solution Approach 1:
The patent segments the TXOP into smaller time intervals by introducing TXOP preemption mechanisms. The access point can preempt ongoing long TXOP transmissions to allow low latency devices to access the channel, effectively dividing the continuous transmission opportunity into manageable segments that balance throughput and latency requirements
Solution Approach 2:
The patent introduces dynamic TXOP adjustment where the access point can modify the transmission opportunity duration based on real-time conditions. By dynamically preempting long TXOPs when low latency devices need access, the system adapts the TXOP length to minimize latency while maintaining overall throughput efficiency
2Loss of time
If TXOP preemption is implemented for low latency devices, then latency is reduced, but channel access complexity increases
Solution Approach 1:
The patent implements preliminary actions by having low latency devices send preemption requests before they need to transmit. The access point evaluates these requests in advance and makes preemptive decisions before the actual data transmission begins, simplifying the real-time control complexity by performing the decision-making process beforehand
Solution Approach 2:
The access point acts as an intermediary between long TXOP transmissions and low latency device requests. It mediates the channel access by evaluating preemption requests and coordinating between ongoing transmissions and new low latency traffic, centralizing the complexity control in the access point rather than requiring complex peer-to-peer coordination
3Adaptability or versatility
If unregistered low latency devices are allowed to send preemption requests, then device accessibility is improved, but collision probability increases
Solution Approach 1:
The patent implements periodic action by allowing unregistered devices to send preemption requests at specific intervals during the TXOP. Instead of continuous contention, devices can request preemption at designated times, creating a rhythmic access pattern that reduces collisions while maintaining accessibility for both registered and unregistered low latency devices
Data Source
AI summary
This disclosure describes systems, methods, and devices related to enhanced low latency (LL). A device may establish time gaps between consecutive physical layer (PHY) convergence protocol data units (PPDUs) to optimize preemption opportunities for low latency (LL) transmission by one or more station devices (STAs). The device may identify a preemption request (PR) frame received from at least one of the one or more STAs including unregistered STAs only or including both unregistered and registered STAs during a time gap, indicating an intent to transmit LL packets when preemption is permitted. The device may determine a preemptability of a current transmit opportunity (TXOP). The device may cause to send a preemption indication in a PPDU preceding the time gap.