Uplink Virtual Queues for Trigger-Based Channel Access
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Solution Overview
Problem
In wireless local area networks (WLANs), contention-based channel access methods often lead to inefficiencies due to unpredictable interference, resulting in reduced communication performance and increased contention among devices, especially when timely trigger frames are not sent, forcing devices to resort to single-user transmission.
Innovation Solution
An access point creates uplink virtual queues based on buffer status reports from devices, initiating backoff counters to transmit trigger frames when a predefined count is reached, ensuring timely and fair channel access, and prioritizing channel access through increased backoff counters during cascaded operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If trigger-based access is used to reduce contention and improve communication performance, then communication performance is improved, but the access point must send trigger frames in a timely manner which becomes difficult under congestion
Solution Approach 1:
The patent applies preliminary action by having electronic devices submit uplink data to the access point before the actual transmission time. The access point receives and buffers uplink data from multiple devices in advance, then sends trigger frames to coordinate simultaneous transmissions. This advance preparation ensures that when trigger frames are sent, the data is already ready for immediate transmission, eliminating delays caused by real-time data preparation and ensuring timely trigger frame delivery even under congestion.
2Device complexity
If fully distributed channel access is used, then access point complexity is reduced and deployment is simpler, but unpredictable interference increases and coordination becomes challenging
Solution Approach 1:
The patent applies the intermediary principle by introducing a trigger frame mechanism as a mediator between the access point and electronic devices. The access point sends trigger frames that contain coordination information to multiple devices, enabling them to transmit simultaneously without collision. This intermediary signal resolves the coordination challenge of distributed access while keeping the access point relatively simple, as it only needs to send trigger frames rather than manage complex real-time arbitration.
3Productivity
If multiple electronic devices transmit simultaneously using multi-user transmission, then contention is reduced, but resource allocation coordination becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the uplink transmission resources into separate resource units, each assigned to a specific electronic device. The trigger frame contains resource allocation information that segments the available bandwidth and time resources among multiple devices. This segmentation approach enables simultaneous transmissions while simplifying resource allocation coordination, as each device knows its specific resource unit and transmits independently without needing complex inter-device coordination.
Data Source
AI summary
An access point may receive, from a set of electronic devices, one or more buffer status reports that indicate that at least a subset of the electronic devices have uplink data associated with one or more access categories. In response, the access point may create a group of uplink virtual queues for one or more electronic devices in the subset based on the one or more buffer status reports, where a given uplink virtual queue corresponds to a particular access category and a given electronic device. The access point may start one or more backoff counters with a one-to-one correspondence to uplink virtual queues in the group of uplink virtual queues. When a backoff counter for the given uplink virtual queue reaches zero, the access point may transmit a trigger frame to an electronic device in the subset that corresponds to the given uplink virtual queue.