Trigger-Based Acknowledgement for MU PPDU Collision Avoidance
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Solution Overview
Problem
In multi-user (MU) transmission environments, existing WLAN systems face challenges in efficiently acknowledging physical layer (PHY) Protocol Data Units (PPDUs) due to potential collisions when multiple stations transmit acknowledgements using the same resources.
Innovation Solution
The implementation of a trigger-based immediate acknowledgement mechanism, where stations that successfully decode trigger information for an uplink MU transmission transmit acknowledgement frames in an MU manner, while stations that fail to decode the trigger information refrain from transmitting acknowledgement frames until after the UL MU transmission has finished.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple stations transmit acknowledgements using the same transmission resource, then the acknowledgement process is simplified, but collision occurs among acknowledgement frames
Solution Approach 1:
The patent segments the transmission resources by introducing trigger frames that allocate specific resources to different stations. Instead of all stations using the same resource simultaneously, the AP divides the uplink transmission opportunities into separate resources through trigger frame scheduling, allowing multiple stations to transmit acknowledgements without collision.
Solution Approach 2:
The patent applies preliminary action by having the AP send trigger frames before the actual acknowledgement transmission. These trigger frames pre-allocate transmission resources and provide uplink scheduling information to stations, enabling them to transmit acknowledgements at predetermined times without collision.
2Loss of time
If stations transmit immediate acknowledgements, then the response time is reduced, but collision risk increases when multiple stations use the same resource
Solution Approach 1:
The patent uses trigger frames to pre-schedule immediate acknowledgement transmissions. The trigger frame contains uplink scheduling information that tells each station when to transmit its acknowledgement immediately, but at different predetermined times, thus maintaining low delay while avoiding collision through pre-planned resource allocation.
Solution Approach 2:
The patent introduces dynamic resource allocation through trigger frames that can adaptively assign transmission resources based on current network conditions and station requirements. This allows the system to maintain flexibility for immediate acknowledgements while dynamically preventing collisions through real-time resource management.
3Productivity
If all stations are allowed to transmit acknowledgements simultaneously, then the acknowledgement process is efficient, but interference and collision occur
Solution Approach 1:
The patent segments the simultaneous transmission opportunity into multiple time-scheduled transmission slots through trigger frames. Each station is assigned a specific resource within the uplink transmission opportunity, maintaining high throughput by allowing parallel transmissions while preventing collision through resource division.
Solution Approach 2:
The trigger frame acts as an intermediary that coordinates between the AP and multiple stations. It carries uplink scheduling information that mediates the transmission timing and resources, enabling efficient simultaneous acknowledgements while preventing harmful collisions through centralized coordination.
Data Source
AI summary
A network device to function as an Access Point (AP) in a Wireless Local Area Network (WLAN) is provided. The AP is configured to acknowledge a data frame transmitted by a station (STA) in an uplink multi-user physical layer protocol data unit (UL MU PPDU). The AP includes one or more memories, a physical layer (PHY) processor, and a media access controller (MAC) processor. Each processor is coupled to the one or more memories, and is configured to receive the UL MU PPDU, decode an acknowledge (ACK) policy field within a data field of the UL MU PPDU, and determine whether an acknowledgement (ACK) policy indicated in the data field signals an implicit block acknowledgement (BlockAck) request. Responsive to a determination that the ACK policy indication signals an implicit acknowledgement policy, the AP is configured to transmit an ACK or BlockAck frame to the STA in either a single user (SU) or a multi user (MU) manner.