Wi-Fi Trigger Frame Scheduling for Deterministic Priority Access
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Solution Overview
Problem
Existing wireless communication protocols, such as conventional Wi-Fi, struggle to provide deterministic performance in industrial environments due to unpredictable access delays and lack of support for converged networks with both periodic and aperiodic traffic types, failing to meet the requirements of industrial automation applications.
Innovation Solution
A priority-based deterministic channel access method using OFDMA-based Wi-Fi with extended trigger frames that allocate resource units based on priority identifiers, combining TDMA and Strict Priority scheduling to manage periodic, aperiodic, and best-effort traffic, ensuring worst-case latency bounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional Wi-Fi contention-based mechanisms are used, then network flexibility and ease of operation are improved, but deterministic performance and reliability deteriorate due to unpredictable access delays
Solution Approach 1:
The patent segments the wireless network into two distinct access mechanisms: contention-based access for best-effort traffic and scheduled access for time-critical traffic. This segmentation allows each traffic type to use the most appropriate access method, with time-critical traffic guaranteed deterministic access through scheduled resource allocation while best-effort traffic maintains flexibility through contention-based access.
Solution Approach 2:
The patent changes the access parameter from purely contention-based to a hybrid mechanism where scheduled transmissions use predetermined time slots and resource units. This parameter change transforms the access behavior from random contention to deterministic scheduling, ensuring predictable latency for time-critical applications.
2Reliability
If wired deterministic protocols are used, then deterministic performance and reliability are improved, but device complexity and installation cost increase
Solution Approach 1:
The patent substitutes the mechanical wired connection system with a wireless system that implements deterministic scheduling. By replacing physical cable connections with wireless OFDMA transmissions and scheduled resource allocation, the patent achieves deterministic performance without the installation complexity and physical constraints of wired networks.
Solution Approach 2:
The patent makes the wireless access point universal by enabling it to handle multiple traffic types (time-critical, periodic, and best-effort) through a single hybrid access mechanism. This multi-functionality allows the wireless network to replace multiple specialized networks (wired deterministic, wireless best-effort) with a single converged infrastructure.
3Loss of time
If resource allocation is prioritized for periodic traffic, then latency for periodic traffic is reduced, but bandwidth availability for aperiodic traffic deteriorates
Solution Approach 1:
The patent implements dynamic resource allocation where the access point adjusts resource unit allocation based on real-time traffic conditions. For periodic traffic, dedicated resource units are allocated to ensure latency requirements are met, while aperiodic traffic utilizes remaining bandwidth and contention-based access mechanisms to optimize overall network utilization.
Solution Approach 2:
The patent applies partial scheduling action where only the minimum necessary resources are reserved for periodic traffic to meet latency requirements, leaving excess bandwidth available for aperiodic traffic. This partial allocation ensures deterministic performance for time-critical applications while maximizing overall network efficiency.
Data Source
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AI summary
The present embodiments relate to a method and access point for providing a priority-based deterministic channel access in a wireless local area network. According to the invention, trigger frames or scheduled trigger frames, in particular trigger frames as used in OFDMA-based Wi-Fi are used to enable time sensitive behavior by combining a schedule of temporally ordered transmission opportunities for transmitting the data with a - strict or non-strict - priority scheduling to further improve the performance of aperiodic traffic in Wi-Fi. The present invention advantageously provides resource allocation mechanism guaranteeing worst-case latency bounds in a converged industrial network environment. The resource allocation or resource scheduling advantageously guarantees that specific devices are allocated with enough resources to transmit traffic according to their strict timing requirements while considering periodic and aperiodic deterministic traffic.