Sequential ACK Policy for Multi-User Wireless Response Ordering
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Solution Overview
Problem
Conventional systems face inefficiencies in organizing response Transmit Opportunities (TXOPs) from multiple receivers in Multi-User (MU) wireless communications, as the transmitting Access Point (AP) lacks knowledge of optimal response slot length due to unknown uplink rates and data amounts, leading to conservative estimates and wasted time slots.
Innovation Solution
Implementing a Sequential ACK acknowledgment policy, where stations determine their response position based on their order within a group identified by a group identifier, allowing for efficient ordering of acknowledgments within a multi-user transmission sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the AP provides a specified time slot for responses after downlink transmission, then stations can send acknowledgments, but the time slot length is either too long (conservative estimate) or too short (insufficient for all stations), leading to wasted time slots
Solution Approach 1:
The response opportunity is segmented into multiple individual response positions, one for each station in the multi-user group. Each station is assigned a specific response position based on its order in the group, rather than using a single collective time slot. This segmentation allows each station to transmit its acknowledgment at its designated position without waiting for others, eliminating the waste of time when some stations have already sent their acknowledgments while the slot continues.
Solution Approach 2:
The AP determines and signals the response position for each station in advance, before the actual acknowledgment transmission occurs. By pre-assigning response positions based on the station order in the group and signaling this information in the downlink transmission, stations know exactly when to send their acknowledgments without needing to wait or estimate, thus optimizing the use of response time.
2Loss of time
If the AP specifies the response time slot, then stations can send acknowledgments, but the AP does not know the optimal length because uplink rate and data amount are unknown
Solution Approach 1:
The AP performs preliminary determination of response positions based on station order in the group before transmission. By pre-calculating and signaling the response position for each station in advance, the system eliminates the need for the AP to know the optimal slot length in advance, as each station independently transmits at its predetermined position.
Solution Approach 2:
Each station independently determines its own response position based on its order in the group and the Sequential ACK policy, then transmits its acknowledgment at that position without requiring coordination or information from other stations about their data amounts or rates. This self-service approach allows each station to optimize its transmission independently.
3Loss of time
If conventional time slot allocation is used, then all stations can send acknowledgments, but time slots are wasted when stations do not receive or cannot send in the allocated slot
Solution Approach 1:
The response opportunity is divided into discrete response positions assigned to individual stations based on their order in the group. This segmentation ensures that each station has a dedicated transmission opportunity, eliminating the waste that occurs in conventional systems when some stations fail to utilize the allocated time slot while others are still transmitting.
Solution Approach 2:
The system dynamically adapts to each station's needs by allowing stations to transmit at their specific response positions regardless of what other stations do. If a station cannot transmit at its designated position, that time is not wasted because other stations can still transmit at their own positions, making the overall system more resilient and efficient.
Data Source
AI summary
Techniques are provided for sending an acknowledgment from a station to an access point in response to a multi-user transmission, which may include receiving a multi-user transmission addressed to a multi-user group including the station, determining a response position of the station in a sequence of responses based on an order of the station in the group, and sending the acknowledgment in the determined response position. Techniques are also provided for ordering acknowledgments from a group of stations addressed in a multi-user transmission from an access point, which may include selecting a group identifier to identify the group of stations to receive the multi-user transmission, configuring a header portion of the multi-user transmission to indicate a Sequential ACK acknowledgment policy for station responses based on an order of the stations in the group, and transmitting the multi-user transmission to the group.