WLAN PPDU Preemption Signaling for Ultra-Low Latency
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Solution Overview
Problem
Current WLAN standards, such as IEEE 802.11, fail to meet the ultra-low latency requirements of applications like augmented reality, virtual reality, and industrial IoT, necessitating a new low-latency mechanism without altering the physical layer frame structure.
Innovation Solution
Implementing a communication method that includes a first station generating a PPDU with fields indicating preemption capabilities, such as 'Preemption Allowed', 'Preemption Initiator', and 'Preemption PPDU Number', to prioritize low-latency data transmission and manage preemption operations within the existing frame structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a new low-latency mechanism is introduced to meet ultra-low latency requirements, then latency is reduced, but device complexity increases
Solution Approach 1:
The preemption mechanism is nested within the existing IEEE 802.11 MAC layer framework. The patent introduces preemption fields (Preemption Allowed, Preemption Initiator, Preemption PPDU Number) that are embedded in existing frame structures, allowing the new functionality to be contained within the existing system architecture rather than requiring a complete redesign, thus limiting the increase in device complexity while achieving ultra-low latency
Solution Approach 2:
The patent implements preliminary actions by setting preemption indication fields in advance within the frame structure. The Preemption Allowed field is set before transmission to indicate whether preemption can occur, and the Preemption Initiator field identifies which station is allowed to preempt. This preliminary configuration enables rapid preemption execution when needed without requiring complex real-time decision-making logic, reducing latency while keeping device complexity manageable
2Loss of time
If preemption fields are added to the frame structure, then low-latency transmission is enabled, but frame structure complexity increases
Solution Approach 1:
The patent applies local quality by adding preemption-related fields only to specific frame types that require low-latency transmission, rather than modifying all frame structures. The Preemption Allowed, Preemption Initiator, and Preemption PPDU Number fields are selectively included in frames where preemption is needed, maintaining simplicity in frames where preemption is not applicable while enabling low-latency transmission where required
3Productivity
If preemption operation is allowed, then low-latency service transmission is improved, but collision probability increases
Solution Approach 1:
The patent implements feedback mechanisms through the Preemption PPDU Number field, which indicates the number of PPDUs that have been preempted or will be preempted. This feedback information allows stations to track preemption occurrences and adjust their transmission behavior accordingly, helping to reduce collision probability by providing visibility into the preemption state of the medium while maintaining high productivity for low-latency services
Data Source
AI summary
The method includes: A first station generates a first physical layer protocol data unit PPDU, where the first station includes an access point supporting preemption or a non-access point station supporting preemption, the first PPDU includes any one or more of a first field, a second field, and a third field, the first field indicates whether a preemption operation is allowed to be performed after sending of the first PPDU is completed, the second field indicates a type of a station that is allowed to perform a preemption operation after sending of the first PPDU is completed, and the third field indicates a number of PPDUs that are sent after sending of the first PPDU is completed and on which a preemption operation is allowed to be performed; and the first station sends the first PPDU.