LDPC Rate Matching Without Pre-FEC Padding in Wireless Networks
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Solution Overview
Problem
Existing mechanisms for performing rate matching in low-density parity check (LDPC) codes in wireless networks are complex and inefficient, often requiring pre-FEC padding, puncturing, shortening, and repetition, which increase redundancy and reduce performance.
Innovation Solution
A mechanism that omits pre-FEC padding by indicating the AMPDU payload size in a PHY-specific preamble, calculates the number of OFDM symbols and filler bits, and distributes filler bits as repeating bits to stabilize code word size, eliminating the need for puncturing and shortening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pre-FEC padding, puncturing, shortening, and repetition are used in rate matching, then the payload can be adjusted to fill OFDM symbols, but redundancy increases and performance decreases
Solution Approach 1:
The patent extracts and removes the pre-FEC padding step from the traditional rate matching process. By indicating the AMPDU payload size directly in the PHY-specific preamble, the system eliminates the need to add and subsequently remove padding bits, thereby reducing redundancy while maintaining rate matching capability.
Solution Approach 2:
The patent changes the parameter representation by indicating the exact AMPDU payload size in the PHY-specific preamble rather than using fixed padding schemes. This parameter change allows the system to adapt the code word size to the actual payload requirements, reducing unnecessary redundancy and improving transmission performance.
2Stability of the object's composition
If pre-FEC padding is used to fill OFDM symbols, then the payload can be aligned to symbol boundaries, but the code word size becomes unstable and requires additional processing
Solution Approach 1:
The patent performs preliminary action by indicating the AMPDU payload size in the PHY-specific preamble before the actual transmission processing. This allows the receiving end to pre-calculate the exact number of filler bits and OFDM symbols needed, eliminating the need for complex post-processing and stabilizing the code word size without requiring pre-FEC padding.
Solution Approach 2:
The patent introduces the PHY-specific preamble as an intermediary that carries the AMPDU payload size information. This intermediary enables both transmitting and receiving ends to agree on the exact payload parameters in advance, simplifying the rate matching process and stabilizing code word size without complex padding and unpadding operations.
3Stability of the object's composition
If filler bits are added to fill OFDM symbol boundaries, then the transmission structure is maintained, but redundancy increases and performance is reduced
Solution Approach 1:
The patent changes the approach to filler bits by calculating the exact number needed based on the indicated AMPDU payload size and distributing them as repeating bits at code word boundaries. This precise parameter control maintains OFDM symbol structure while minimizing redundancy and improving transmission performance compared to traditional pre-FEC padding methods.
Data Source
AI summary
This disclosure describes mechanisms for performing rate matching in low-density parity check (LPDC) codes in a wireless network. A device may generate an Aggregated Media Access (MAC) Protocol Data Unit (AMPDU) payload having an AMPDU payload size associated with a number of bits. The device may omit pre-Forward Error Correction (FEC) padding of the AMPDU payload at a MAC layer by indicating the AMPDU payload size in a physical layer (PHY)-specific preamble. The device may then generate the PHY-specific preamble comprising the AMPDU payload size without the pre-FEC padding. The device may also calculate a number of Orthogonal Frequency Division Multiplexing (OFDM) symbols for containing the number of bits and transmit the PHY-specific preamble and the number of OFDM symbols to a station device.