HARQ Retransmission Overhead Reduction via Bitmap Segmentation
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Solution Overview
Problem
In wireless local area networks (WLANs), the existing HARQ (Hybrid Automatic Repeat Request) technique faces challenges in efficiently determining the codeword to be retransmitted due to mismatched transmission units and encoded codewords, leading to increased overhead and complexity in error correction processes.
Innovation Solution
A method is proposed where the transmitting STA encodes at least one first codeword based on multiple data blocks, transmits it, and upon receiving an error detection signal, encodes a second codeword using the first data block and contiguous data blocks to minimize overhead by aligning the codeword transmission with the HARQ transmission unit, ensuring efficient retransmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the transmitting STA encodes multiple data blocks into a single codeword for HARQ retransmission, then the overhead is reduced and transmission efficiency is improved, but the complexity of determining which data blocks to retransmit increases
Solution Approach 1:
The patent segments the determination process by introducing a bitmap field that individually identifies each data block requiring retransmission. This allows the system to maintain segmented control over multiple data blocks while transmitting them as a unified codeword, resolving the contradiction between reduced overhead and increased complexity.
Solution Approach 2:
The receiving STA provides feedback through the bitmap field indicating which specific data blocks contain errors. This feedback mechanism enables the transmitting STA to precisely identify which data blocks need retransmission without increasing overall system complexity, as the bitmap provides clear, structured information about error locations.
2Loss of substance
If the transmitting STA uses a single CRC for the entire codeword instead of individual CRCs for each data block, then the overhead is minimized, but the precision of error detection for individual data blocks decreases
Solution Approach 1:
The patent applies segmentation by dividing the error detection function: the single CRC checks the entire codeword for overall integrity, while the bitmap field provides segmented identification of which specific data blocks contain errors. This segmentation maintains low overhead while preserving precise error detection capability.
Solution Approach 2:
The bitmap field acts as an intermediary between the single CRC check and the individual data blocks. It translates the overall codeword validation result into specific identification of erroneous blocks, enabling precise error detection without requiring multiple CRCs and thus minimizing overhead.
3Productivity
If the transmitting STA retransmits only the erroneous data block, then the transmission efficiency is improved, but the adaptability to handle multiple simultaneous errors decreases
Solution Approach 1:
The patent implements dynamics by making the retransmission content adaptive based on the error pattern indicated in the bitmap. The system dynamically determines which data blocks to retransmit by examining the bitmap, allowing it to handle any number of simultaneous errors efficiently while maintaining adaptability to different error scenarios.
Solution Approach 2:
The bitmap mechanism provides universality by enabling the system to handle various error patterns (single error, multiple errors, contiguous errors, non-contiguous errors) through a single unified approach. The same bitmap-based identification method works for all error scenarios, maintaining both efficiency and adaptability.
Data Source
AI summary
In a wireless local area network (LAN) system, a transmitting STA can encode at least one codeword on the basis of a plurality of data blocks. The transmitting STA can encode a second codeword on the basis of a first data block and a second data block that is continuous with the first data block, in response to a first data block transmission request signal from among the plurality of data blocks. The transmitting STA can transmit the encoded second codeword to a receiving STA.