Multi-AP HARQ Packet Combining for WLAN Reliability
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Solution Overview
Problem
Current wireless communication protocols, such as 802.11, face challenges in adapting to new use cases and improving performance in multi-access point (AP) environments, particularly in managing hybrid automatic repeat request (HARQ) transmissions effectively across multiple stations (STAs).
Innovation Solution
The implementation of multi-AP HARQ transmission methods, where a station (STA) monitors a channel, receives packets from multiple APs, determines if they are part of a multi-AP HARQ transmission, combines packets, and sends acknowledgments based on a timer and acknowledgment policy, while APs transmit and receive feedback responses to manage resource units for uplink transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-AP HARQ transmission is implemented, then reliability of data transmission is improved, but device complexity increases
Solution Approach 1:
The patent segments the HARQ process into distinct phases: initial transmission phase, feedback collection phase, and retransmission phase. Each access point operates independently in its segment, managing its own transmission and feedback collection, which reduces the complexity burden on individual devices while maintaining overall system reliability through coordinated operation across multiple APs.
Solution Approach 2:
The patent introduces a coordinator entity that acts as an intermediary to manage the multi-AP HARQ process. This coordinator receives feedback from multiple APs, makes centralized decisions about retransmission strategies, and coordinates resource allocation. By introducing this intermediary layer, the complexity is centralized rather than distributed across all devices, improving reliability while managing overall system complexity.
2Reliability
If packets are combined from multiple APs, then decoding success rate is improved, but loss of time increases
Solution Approach 1:
The patent implements preliminary actions by having access points prepare and buffer packets in advance before combination is needed. STAs also prepare to receive and combine packets by pre-configuring their combining algorithms and buffers. This preliminary preparation reduces the actual combination time when retransmission occurs, improving decoding success rate while minimizing time loss.
Solution Approach 2:
The patent maintains continuity of useful action by overlapping the packet combination process with other STA operations. While combining packets from multiple APs, the STA continues other processing tasks. Additionally, the feedback mechanism is designed to trigger retransmission decisions continuously rather than in discrete batches, keeping the system in a state of productive operation throughout the HARQ process.
3Productivity
If H-ARQ feedback response trigger messages are transmitted, then acknowledgment efficiency is improved, but use of energy increases
Solution Approach 1:
The patent implements periodic action by transmitting H-ARQ feedback response trigger messages at regular intervals rather than continuously. The system collects feedback from STAs periodically and batches retransmission decisions. This periodic approach maintains acknowledgment efficiency by ensuring timely feedback while significantly reducing energy consumption compared to continuous feedback transmission.
Solution Approach 2:
The patent uses feedback mechanisms where STAs indicate their decoding status, and the coordinator uses this feedback to make intelligent decisions about when to trigger retransmissions. Rather than transmitting trigger messages unconditionally, the system only triggers feedback responses when actually needed based on STA performance, improving acknowledgment efficiency while reducing unnecessary energy expenditure on feedback transmissions.
Data Source
AI summary
Methods and apparatus for multi-hybrid automatic repeat request (HARQ) transmission are provided. An access point (AP) may transmit a multi-HARQ transmission to a plurality of stations (STAs). The AP may receive a H-ARQ feedback response from the plurality of STAs. The H-ARQ feedback may include a field to indicate that the H-ARQ feedback is a codeword (CW)/CW group (CWG) based acknowledgment. The H-ARQ feedback may include a packet identification (ID). The packet ID may be a HARQ transmission ID, a sequence number, a MPDU ID or a PPDU ID. The packet ID may be carried in a PLCP header. The H-ARQ feedback may be an aggregated CW/CWG acknowledgment. The H-ARQ feedback may be carried in a null data packet (NDP). A PLCP header of the NDP packet may include a wideband PLCP header and a narrow band PLCP header.