Uplink LDPC FEC Encoding Aligned With PON Grant Granularity
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Solution Overview
Problem
Existing passive optical network (PON) technologies lack a method for uplink FEC encoding, leading to inefficiencies and bandwidth waste due to incomplete FEC codewords and varying grant granularities, particularly in high-speed PONs like the 50G PON.
Innovation Solution
Implement an LDPC coding scheme for uplink FEC encoding where the FEC codeword data and parity bits are divisible by the grant granularity, using a mother code matrix to ensure complete codewords and high code rates, and adjust grant granularities to match downlink encoding for compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If uplink FEC encoding is implemented without considering grant granularity alignment, then uplink data transmission can proceed, but incomplete FEC codewords are generated causing bandwidth waste and reduced transmission efficiency
Solution Approach 1:
The patent changes the parameter of FEC codeword length to be aligned with grant granularity. Specifically, it sets the LDPC codeword data bit length to 1760 bytes and grant granularity to 20 bytes, ensuring that the codeword length is an integer multiple of the granularity. This parameter alignment ensures complete codewords are always generated, eliminating bandwidth waste from incomplete codewords while maintaining high transmission efficiency.
2Adaptability or versatility
If downlink LDPC coding scheme is directly applied to uplink without modification, then encoding compatibility is achieved, but uplink-specific requirements for complete codewords and high code rates are not met
Solution Approach 1:
The patent applies local quality by making specific modifications to the downlink LDPC coding scheme to suit uplink requirements. It adjusts the LDPC codeword data bit length to 1760 bytes and sets the mother code matrix to 1760×1824, ensuring that uplink encoding produces complete codewords aligned with grant granularity. These localized modifications maintain compatibility with the downlink scheme while precisely meeting uplink performance requirements.
3Adaptability or versatility
If grant granularity is not aligned with FEC codeword length, then flexible resource allocation is possible, but varying grant granularities cause incomplete codewords and reduced overall code rate
Solution Approach 1:
The patent segments the uplink transmission resource into fixed-size grant units of 20 bytes each, and designs the LDPC codeword data bit length (1760 bytes) to be exactly 88 times the grant granularity. This segmentation approach ensures that any integer number of grants will always produce complete codewords, maintaining high overall code rates while preserving flexibility in allocating different numbers of grants to different users.
Data Source
AI summary
This application provides a method for uplink FEC encoding. On example method includes: obtaining a grant length of an uplink slot, where the grant length is equal to a product of a grant quantity of the uplink slot and a grant granularity, and the grant granularity is a grant granularity supported by a device to which the uplink slot belongs; and obtaining an FEC codeword of uplink data based on the grant length and an LDPC coding scheme, where the FEC codeword includes an LDPC codeword data bit, and in the LDPC coding scheme, N times the LDPC codeword data bit is divisible by the grant granularity, where N is a positive integer greater than or equal to 1.