Slotted Random Access for Low Latency Wireless Preemption
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Solution Overview
Problem
In wireless networks using IEEE 802.11 standards, the inter-PPDU preemption technique can lead to collisions when multiple devices attempt to transmit low latency data during the same interframe space interval, resulting in degraded performance and increased latency.
Innovation Solution
The implementation of a slotted random access technique and a frequency resource random access technique to reduce the probability of collisions. These techniques involve dividing the interframe space into slots or subchannels, allowing devices to randomly select a time slot or subchannel for low latency data transmission, thereby introducing randomness and reducing contention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If inter-PPDU preemption technique is used to allow preemptions during TXOP, then low latency transmission capability is improved, but collision probability increases when multiple devices compete for transmission opportunities
Solution Approach 1:
The interframe space interval is divided into multiple discrete time slots, creating a segmented time structure. Each device selects a specific slot for its preemption attempt, transforming the continuous competition into discrete, non-overlapping opportunities. This segmentation directly reduces collision probability while preserving low latency transmission capability.
Solution Approach 2:
The system dynamically assigns time slots to different devices based on their preemption requests and the current TXOP holder's transmission schedule. The slot assignment adapts to varying transmission conditions and device priorities, creating a dynamic allocation mechanism that optimizes both latency performance and collision avoidance.
2Productivity
If TXOP holder transmits large PPDU continuously, then throughput is improved, but low latency data from other devices is delayed
Solution Approach 1:
The large PPDU transmission is segmented into multiple smaller PPDUs separated by interframe space intervals. This segmentation creates natural interruption points where other devices can attempt preemptions, allowing the TXOP holder to maintain high throughput through continuous transmission while enabling low latency data from other devices to be transmitted when they have urgent data to send.
Solution Approach 2:
The TXOP holder transmits PPDUs in a periodic manner with regular interframe space intervals between transmissions. This periodic action pattern creates predictable transmission rhythms that allow other devices to plan their preemption attempts during these intervals, balancing continuous throughput with low latency requirements.
Data Source
AI summary
An embodiment is method performed by a first wireless device to transmit low latency data using a slotted random access technique. The method includes detecting an end of a fragmented physical layer protocol data unit (PPDU) transmission made by a second wireless device, randomly selecting a slot from a plurality of slots forming a slot window that is to follow a short interframe space (SIFS) interval after the end of the fragmented PPDU transmission, and attempting to transmit low latency data during the randomly selected slot.