LDPC HARQ Retransmission Framing for Packet Combining in Wi‑Fi
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Solution Overview
Problem
Conventional IEEE 802.11 standards do not facilitate efficient packet combining during retransmissions, which hinders the improvement of reception Signal-to-Noise Ratio (SNR) and user throughput.
Innovation Solution
A communication apparatus and method that implement a Hybrid Auto Repeat reQuest (HARQ) scheme using Low Density Parity Check (LDPC) coding, where information blocks are encoded with a prescribed coding rate to generate parity bit sequences, divided into multiple parity blocks, and punctured to adapt to retransmissions, optimizing the number of bits for improved error correction and transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ratio of redundant bits occupying a codeword is increased to improve error correction capability, then the error correction capability is improved, but the amount of decoding processing increases and transmission efficiency is reduced
Solution Approach 1:
The patent divides the parity bit sequence into multiple parity blocks, where each block can be independently processed and combined. This segmentation allows the receiver to accumulate parity information from multiple transmissions without requiring complete retransmission, thereby improving error correction capability while maintaining transmission efficiency through incremental redundancy.
Solution Approach 2:
The patent performs preliminary encoding to generate multiple parity blocks in advance, associating each block with a specific retransmission count. This preliminary preparation enables the receiver to immediately combine received parity blocks without additional processing delay, improving both error correction capability and transmission efficiency.
2Reliability
If conventional IEEE 802.11 standards are used for error control, then ARQ retransmission is performed, but packet combining based on HARQ is not considered making efficient packet combining difficult
Solution Approach 1:
The patent introduces dynamic packet combining mechanisms where the receiver adaptively combines packets from multiple transmissions based on HARQ protocols. The system dynamically selects and combines parity blocks from different retransmissions, optimizing reception SNR while managing complexity through structured combining rules associated with retransmission counts.
Solution Approach 2:
The patent changes the parameter structure by associating each parity block with a specific retransmission count and organizing them in a structured manner. This parameter organization enables efficient packet combining by allowing the receiver to systematically accumulate and process parity information from multiple transmissions, improving reception SNR without excessive complexity.
3Productivity
If LDPC coding is used with multiple parity blocks for HARQ, then efficient packet combining is enabled, but the number of bits in parity blocks must be optimized to balance error correction and transmission efficiency
Solution Approach 1:
The patent optimizes the number of bits in each parity block by adjusting the coding rate and the association between parity blocks and retransmission counts. This parameter optimization ensures that each transmission carries the appropriate amount of redundant information, balancing error correction capability with transmission efficiency in HARQ operations.
Solution Approach 2:
The patent transmits multiple parity blocks with varying degrees of redundancy, where each block provides partial error correction capability. The receiver combines these partial contributions to achieve the required overall error correction performance, allowing flexible adaptation to channel conditions while maintaining transmission efficiency.
Data Source
AI summary
A communication apparatus includes a higher layer unit configured to configure a retransmission scheme, a physical layer frame generator configured to generate a frame using a codeword, and a radio transmitter configured to transmit the frame. In a case that a configuration of the retransmission scheme indicates a Hybrid Auto Repeat reQuest (HARQ), the physical layer frame generator encodes, at a prescribed coding rate, a Low Density Parity Check (LDPC) information block including information bits to generate a parity bit sequence, and divides the parity bit sequence into blocks the number of which is given by a coding rate indicated by a Modulation and Coding Scheme (MCS), to generate multiple parity blocks. Each of the parity blocks is associated with the number of retransmissions. The codeword is generated based on the information bits and one of the parity blocks.