Multi-Link Roaming With Distributed Block Acknowledgment
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Solution Overview
Problem
Existing multi-link device (MLD) architectures face challenges in seamless roaming due to the inefficiency of centralized frame aggregation and block acknowledgment functions across non-collocated access points, leading to delayed acknowledgments and potential service disruptions, especially when client devices operate on multiple RF links.
Innovation Solution
A decentralized architecture is implemented with an Upper Service Access Point (U-SAP) and Lower Service Access Points (L-SAPs) to split logical functions, enabling localized per-Traffic Identifier (TID) frame aggregation and block acknowledgment operations, eliminating transport hops and ensuring timely acknowledgments across non-collocated APs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If centralized frame aggregation and block acknowledgment functions are implemented across non-collocated access points, then multi-link device capacity is increased, but acknowledgment delay increases and service disruptions occur
Solution Approach 1:
The patent segments the centralized frame aggregation and block acknowledgment functions into distributed components at each non-collocated access point. Each AP independently performs frame aggregation and block acknowledgment for its associated links, eliminating the need for centralized processing across multiple APs. This segmentation resolves the contradiction by maintaining multi-link capacity while reducing acknowledgment delay through localized processing.
Solution Approach 2:
The patent extracts the frame aggregation and block acknowledgment functions from the centralized controller and relocates them to the individual non-collocated access points. By taking out these critical functions from the centralized path, the system eliminates transport hops that cause acknowledgment delays while preserving the multi-link device architecture's capacity benefits.
2Productivity
If centralized frame aggregation is used across non-collocated access points, then resource utilization is improved, but service disruptions occur during roaming
Solution Approach 1:
The patent segments the frame aggregation function so that each non-collocated access point independently performs aggregation for its local links rather than relying on centralized processing. This segmentation ensures that during roaming events, each AP can maintain service continuity independently without being affected by centralized controller bottlenecks or failures, thus improving reliability while preserving resource utilization efficiency.
Solution Approach 2:
The patent enables each non-collocated access point to perform frame aggregation and block acknowledgment autonomously without requiring centralized coordination. This self-service capability allows APs to handle roaming events independently, maintaining service continuity and reliability while efficiently utilizing local resources.
3Loss of time
If transport hops are reduced for frame aggregation, then acknowledgment timing is improved, but architectural complexity increases
Solution Approach 1:
The patent extracts the frame aggregation and block acknowledgment functions from the centralized controller and places them at the individual access points. This extraction eliminates multiple transport hops between the centralized controller and APs, improving acknowledgment timing. While this distributes complexity to individual APs, each AP handles only its local links, making the overall architecture more manageable than centralized processing across multiple APs.
Data Source
AI summary
Seamless client roaming for Multi-Link Device (MLD) clients may be provided. First, a Traffic Identifier (TID)-to-link map may be established by an Upper Service Access Point (U-SAP) of a multi-AP MLD entity that assigns subsets of TIDs to at least two links of the entity. For example, a client device logically associates with the U-SAP, while the client device physically connects to a first and second AP of the entity on a respective first and second link, where the first and second AP include first and second Lower Service Access Points (L-SAPs) and are non-collocated. Next, using the map, data received at the U-SAP is directed over one of the two links for transmission to the client device. Further, frame aggregation and block acknowledgment functions may be performed by one of the first or second L-SAP based on whether data transmission is over the first or second link.