WLAN Latency-Sensitive Traffic Transmission via TXOP Preemption
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Solution Overview
Problem
Current wireless local area network (WLAN) technologies face delays in transmitting latency-sensitive traffic due to existing protocols that require latency-sensitive traffic to wait for the completion of non-latency-sensitive traffic transmissions, leading to critical delays.
Innovation Solution
Implementing a method where a WLAN device schedules low-latency traffic stream windows and pre-empts the transmission opportunity (TXOP) of another device if overlap occurs, allowing for immediate transmission of low-latency traffic during the preempted TXOP, utilizing stream classification services and quality of service characteristics to prioritize and manage low-latency traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If existing WLAN protocols require latency-sensitive traffic to wait for completion of non-latency-sensitive traffic transmissions, then transmission order is maintained and protocol simplicity is preserved, but transmission delay increases significantly
Solution Approach 1:
The patent establishes TXOP preemption rights and schedules LL traffic stream windows in advance before actual transmission needs arise. The AP pre-configures when it can preempt non-AP STA TXOPs and when LL traffic is expected, allowing immediate transmission when both conditions align without ad-hoc protocol negotiations.
Solution Approach 2:
The patent segments the transmission medium into dedicated LL traffic stream windows within the TXOP structure. By dividing the TXOP into segments where preemption is allowed and where it is not, and by creating separate scheduling tracks for LL and non-LL traffic, the system reduces waiting time while maintaining overall protocol structure.
2Speed
If TXOP preemption is implemented to allow immediate LL traffic transmission, then transmission latency is reduced, but network scheduling complexity increases
Solution Approach 1:
The patent implements periodic LL traffic stream windows at predetermined intervals within the TXOP structure. This periodic scheduling allows the AP to anticipate when LL traffic will arrive and pre-configures preemption rights in advance, enabling high-speed transmission without requiring complex real-time scheduling decisions.
Solution Approach 2:
The patent makes the TXOP structure dynamic by allowing the AP to adjust the allocation of LL traffic stream windows and preemption rights based on traffic conditions. The system can dynamically enable or disable preemption for specific TWT SPs and adjust the frequency and timing of LL traffic windows to match actual network needs.
3Loss of time
If LL traffic is prioritized over TWT scheduled transmissions, then LL traffic latency is reduced, but TWT service reliability may be compromised
Solution Approach 1:
The patent applies different quality characteristics to different parts of the TXOP structure. Specific time windows are designated with high priority for LL traffic where preemption is enabled, while other portions maintain standard TWT scheduling guarantees. This localized differentiation allows LL traffic to receive expedited handling without compromising the overall reliability of TWT services.
Solution Approach 2:
The patent changes scheduling parameters dynamically based on traffic type. When LL traffic is detected during a scheduled TWT SP, the system modifies the scheduling parameters for that specific window to allow preemption, while other TWT SPs continue with their original parameters. This selective parameter adjustment maintains TWT reliability while enabling LL traffic priority when needed.
Data Source
AI summary
One example discloses a method of latency-sensitive traffic transmission for communications between a first WLAN (wireless local area network) device and a second WLAN device, including: scheduling, by the first WLAN device a set of low latency (LL) traffic stream windows with the second WLAN device; having LL traffic for transmission during at least one of the LL traffic stream windows; pre-empting, by the first WLAN device, a TXOP (transmission opportunity) of the second WLAN device if the at least one of the LL traffic stream windows overlaps with the second WLAN device's TXOP; and transmitting, by the first WLAN device, the LL traffic during the TXOP of the second WLAN device that was pre-empted.