Smart HARQ for WiFi Reliability and Error Control
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Solution Overview
Problem
Current WiFi communication standards, such as 802.11, have inadequate error control mechanisms, leading to inefficiencies in data transmission reliability and error correction in wireless local area networks (WLANs).
Innovation Solution
Implementing Hybrid Automatic Repeat Request (HARQ) systems in WiFi devices, which use ACK/NACK information and redundancy versions to ensure correct data transmission by retransmitting packets with error correction codes, allowing for improved error control and reliability through Chase Combining and Incremental Redundancy schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ACK/NACK mechanisms are used in WiFi, then device complexity is reduced, but data transmission reliability is insufficient
Solution Approach 1:
The patent combines multiple error control functions into a unified HARQ mechanism that integrates error detection, error correction, and automatic retransmission requests. The receiver merges multiple transmissions of the same data packet using combining algorithms (soft combining, chase combining, or incremental redundancy) to improve decoding reliability without requiring separate error control subsystems.
Solution Approach 2:
The transmitter performs preliminary error correction encoding before transmission by adding redundancy bits to the data packet. The receiver performs preliminary error detection and correction attempts before requesting retransmission. This preliminary action reduces the need for multiple retransmissions and improves overall transmission reliability.
2Reliability
If retransmission mechanisms are implemented, then error correction capability is improved, but transmission time increases
Solution Approach 1:
The HARQ mechanism maintains continuous transmission by allowing the receiver to process and combine incoming packets in parallel while the transmitter continues sending data. The receiver performs error correction and decoding operations concurrently with packet reception, eliminating idle time between transmissions and maintaining continuous useful action throughout the communication process.
Solution Approach 2:
The system skips unnecessary retransmission delays by implementing fast HARQ feedback mechanisms where the receiver immediately sends ACK/NACK responses upon decoding success or failure. When errors are detected, the system rushes through the error correction process using pre-configured combining algorithms and redundancy information, minimizing the time spent on error handling.
3Reliability
If redundancy versions are used for retransmission, then error control is improved, but data transmission efficiency decreases
Solution Approach 1:
The system dynamically selects the appropriate error control strategy based on channel conditions and packet importance. The transmitter can switch between different redundancy versions (RV0, RV1, RV2, RV3) and combining methods (soft combining, chase combining, incremental redundancy) adaptively. This dynamic adjustment optimizes the balance between error control performance and transmission efficiency for different traffic types and channel states.
Solution Approach 2:
The HARQ mechanism changes key transmission parameters including redundancy version, coding rate, and modulation scheme based on feedback from previous transmissions. The system adjusts the amount of redundancy added to packets and the combining algorithm used based on observed error rates and channel conditions, optimizing the trade-off between error control and transmission efficiency through parameter adaptation.
Data Source
AI summary
Systems, methods, and instrumentalities are provided to implement a method of communicating a feedback in a wireless local area network (WLAN). A WLAN device may receive a data frame with a hybrid automatic repeat request (HARQ) data indicator in a frame header. The WLAN device may send an acknowledgement frame when the data frame is correctly received and decoded. The WLAN device may send a negative acknowledgement frame when the data frame is not correctly received and decoded.