HARQ PDU Alignment in WLAN Systems

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Solution Overview

Problem

The implementation of Hybrid Automatic Repeat Request (HARQ) in wireless local area networks (WLANs) using IEEE 802.11 protocols is challenging due to difficulties in detecting protocol data units for correction and utilizing aggregated protocol data units for efficient transmission over wireless networks.

Innovation Solution

A method is introduced to align the sizes of Protocol Data Units (PDUs) with the lengths of corresponding information blocks of an error correction code by determining the information block length, inserting padding bits, and encoding the PDUs to ensure alignment with an integer multiple of the block length, facilitating efficient transmission and correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If HARQ capability is added to IEEE 802.11 WLAN protocols, then error correction and retransmission efficiency is improved, but protocol complexity and implementation difficulty increase

Engineering Contradiction:

Improveerror correction capabilityVSAvoidprotocol implementation complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the protocol design by separating HARQ-specific functions from the existing IEEE 802.11 framework. It introduces distinct HARQ indicator fields, separate buffering mechanisms, and dedicated retransmission management structures that operate alongside but independently from standard WLAN protocols, thereby adding reliability without overwhelming system complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary actions by pre-configuring HARQ processes including establishing buffer structures, defining indicator field formats, and setting up retransmission parameters before actual data transmission begins. This preparatory setup enables seamless error correction integration without requiring complex real-time decision-making during data flow

Inventive Principle:

Principle #10Preliminary action

2Productivity

If protocol data units are aggregated for efficient transmission, then transmission efficiency is improved, but detection and correction of individual PDUs becomes more difficult

Engineering Contradiction:

Improvetransmission efficiencyVSAvoidPDU detection difficulty

Core Design Contradiction:

ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces intermediary elements including PDU delimiters, individual PDU headers with sequence numbers, and HARQ-specific indicator fields that act as mediators between aggregated PDUs. These intermediaries enable the receiver to identify, detect, and manage individual PDUs within the aggregated stream, maintaining transmission efficiency while solving the detection difficulty

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies local quality by assigning unique identifiers, sequence numbers, and individual error detection fields to each PDU within the aggregated transmission. This allows selective detection and correction of specific PDUs rather than treating the aggregation as a single unit, thereby maintaining both efficiency and detectability

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If padding bits are inserted to align PDU sizes with error correction block lengths, then encoding efficiency is improved, but transmission overhead increases

Engineering Contradiction:

ImprovePDU size alignmentVSAvoidtransmission overhead

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The patent employs parameter changes by dynamically adjusting padding bit insertion based on the specific requirements of each error correction code block. Rather than using fixed padding, the system calculates the exact number of padding bits needed to align PDU sizes with code block lengths, minimizing overhead while achieving precise alignment for optimal encoding efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies partial action by inserting padding bits only where necessary to achieve alignment, rather than uniformly padding all PDUs. This selective approach ensures that padding is applied minimally and only to the extent required for error correction block alignment, reducing overall transmission overhead while maintaining encoding efficiency

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20230133677A1Physical (PHY) layer design for hybrid automatic repeat request (HARQ) in wireless local area network (WLAN) system

Publication Date: 2023.05.04 INTERDIGITAL PATENT HOLDINGS INC

AI summary

A method to transmit data from a wireless apparatus includes determining an information block length corresponding to an error correction code, inserting padding bits into at least one protocol data unit, PDU, of a plurality of PDUs such that a padded PDU size is an integer multiple of the determined information block length, and wherein each PDU in a frame of PDUs to be transmitted comprises a PDU size that is an integer multiple of the determined information block length, and transmitting the frame encoded by the error correction code with the determined information block length to a wireless receiver.