Wireless LAN Device Retransmission Control via Coded Data Segmentation
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Solution Overview
Problem
Wireless LAN systems face challenges in reducing wasteful retransmission processing and improving communication channel efficiency due to difficulties in applying Hybrid Automatic Repeat Request (HARQ) techniques, especially with variable-length data, where retransmissions are not effectively controlled in units of Protocol Data Units (MPDUs).
Innovation Solution
The system divides MPDUs into fixed-length coded data blocks, adds sequence numbers, and aggregates them into physical layer frames, allowing for efficient retransmission control in units of coded data rather than MPDUs, using a physical layer header to manage block lengths and sequence information for error detection and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ is applied to wireless LAN systems with variable-length MPDUs, then retransmission processing can be performed, but it becomes difficult to control retransmissions in units of MPDUs due to fragment processing requirements
Solution Approach 1:
The patent segments the variable-length MPDU into multiple fixed-length coded data blocks (e.g., 2048 bytes each). Each block is independently numbered and can be individually retransmitted. This segmentation resolves the contradiction by enabling HARQ-style block-level retransmission control while avoiding the complexity of managing variable-length MPDU fragments, as each fixed block can be handled independently through simple sequence number tracking.
2Ease of operation
If retransmission control is performed in units of MPDUs, then sequence management is simplified, but wasteful retransmissions occur when only partial data is corrupted
Solution Approach 1:
By dividing the MPDU into multiple fixed-length coded blocks with individual sequence numbers, the system enables selective retransmission of only the corrupted blocks rather than retransmitting the entire MPDU. This segmentation achieves both goals: sequence management remains simple through sequential numbering, while retransmission efficiency improves by avoiding wasteful retransmission of intact data portions.
Solution Approach 2:
The patent applies local quality by treating each coded data block as an independent unit with its own error detection and retransmission status. This allows the system to apply retransmission resources selectively to only those blocks that require correction, rather than uniformly retransmitting the entire MPDU, thereby reducing overall retransmission overhead while maintaining simple sequence management through block-level tracking.
3Adaptability or versatility
If variable-length MPDUs are transmitted, then communication flexibility is improved, but fragment processing for predetermined access control becomes difficult
Solution Approach 1:
The patent segments variable-length MPDUs into fixed-length coded data blocks (e.g., 2048 bytes each) that can be independently managed. This segmentation resolves the contradiction by maintaining the adaptability of variable-length MPDU transmission while simplifying access control through uniform fixed-length block processing. Each block can be individually controlled and retransmitted without complex fragment management, as the fixed length enables predetermined access control mechanisms to work efficiently.
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AI summary
[Object] To make it possible to reduce wasteful retransmission processing and improve use efficiency of communication channels with regard to wireless LAN systems. [Solving Means] There is provided a wireless LAN communication apparatus including: a transmitter that transmits a data frame storing a plurality of fixed-length pieces of coded data for which it is possible to determine whether or not decoding is successfully performed; and a controller that controls retransmission processing in units of the pieces of coded data.