Multi-Link WLAN Backoff Synchronization for Fair Channel Access
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Solution Overview
Problem
Single-link (SL) entities face a disadvantage in channel contention when deployed alongside multi-link (ML) entities in a WLAN, affecting their proper communication due to higher channel acquisition probabilities.
Innovation Solution
Implementing a backoff procedure only on the primary link of an ML entity, ensuring that channel access is synchronized across all links, and adjusting transmission strategies based on link availability to equalize channel contention probabilities with SL entities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an ML entity performs channel access on multiple links simultaneously with backoff counters on each link, then the ML entity can acquire channels more quickly and improve throughput, but the SL entity is at a disadvantage in channel contention and cannot communicate properly
Solution Approach 1:
The patent segments the backoff mechanism by placing backoff counters only on the primary link rather than on all links. This segmentation allows the ML entity to maintain fairness with SL entities on the primary link while still benefiting from multi-link operation. The primary link acts as the contention point where fairness is ensured, while secondary links can be accessed when available without compromising SL entity fairness.
Solution Approach 2:
Instead of having the ML entity compete on all links (which gives it an advantage), the patent inverts the approach by having the ML entity compete only on the primary link using the same backoff mechanism as SL entities. This inversion ensures that SL entities are not disadvantaged, while the ML entity can still utilize multiple links for throughput improvement by accessing secondary links when they become available.
2Productivity
If an ML entity uses multiple frequency bands for data transmission, then the bandwidth increases and throughput is significantly improved, but the complexity of channel access and synchronization across links increases
Solution Approach 1:
The patent merges the channel access control for multiple links into a single backoff counter on the primary link. Instead of managing independent backoff counters on each link (which would increase complexity), the ML entity uses one backoff counter that controls access to the primary link, and from there can access secondary links. This merging simplifies the channel access management while still enabling multi-link operation for improved throughput.
Solution Approach 2:
The primary link serves multiple functions: it acts as the contention point for channel access (like a traditional single-link system), it coordinates access to secondary links, and it maintains fairness with SL entities. This multi-functionality of the primary link reduces the overall system complexity while enabling the ML entity to operate on multiple frequency bands for improved throughput.
Data Source
AI summary
A ML entity performs a backoff procedure of the primary link based on the backoff counter of the primary link; and when a count value of the backoff counter is 0, the ML entity sends a first PPDU on each first link in K first links, where the K first links include the primary link and K−1 first nonprimary links, and the first nonprimary link is in an idle state in a first inter-frame space before a time point at which the count value of the backoff counter decreases to 0.