LDPC Rate Matching with Lifting-Size Bit Selection
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Solution Overview
Problem
Existing methods for rate matching in LDPC communication systems, particularly in high order modulation and fading channels, result in unstable data retransmission performance due to ineffective starting bit selection and processing techniques, leading to poor system performance.
Innovation Solution
A method for selecting starting bit locations based on redundancy versions and employing bit interleaving schemes, such as block interleaving with column permutations, to stabilize retransmission performance and improve transmission efficiency in LDPC coded data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing starting bit selection methods are used in rate matching, then the encoding process can be completed, but the retransmission performance becomes unstable
Solution Approach 1:
The patent changes the parameter of starting bit selection by introducing a new selection criterion based on the relationship between the starting bit position and the lifting size. Specifically, it selects the starting bit position such that it is an integer multiple of the lifting size, which stabilizes the retransmission performance by ensuring consistent alignment with the quasi-cyclic structure of the LDPC code.
Solution Approach 2:
The patent performs preliminary action by pre-determining the starting bit position in the rate matching process based on the lifting size parameter. This preliminary selection ensures that subsequent retransmissions will have stable performance by establishing the correct alignment before the actual transmission begins.
2Reliability
If conventional rate matching is applied without optimized starting bit selection, then transmission can proceed, but system performance deteriorates in high order modulation and fading channels
Solution Approach 1:
The patent addresses the harmful effects of channel fading and noise by changing the starting bit position parameter in a controlled manner. By selecting starting positions that are integer multiples of the lifting size, the system optimizes the distribution of transmitted bits across the channel, making the system more robust against fading and noise in high order modulation schemes.
3Ease of operation
If rate matching is performed without considering lifting size alignment, then the process is simpler, but retransmission performance varies significantly
Solution Approach 1:
The patent introduces a simple parameter change rule: select the starting bit position as an integer multiple of the lifting size. This rule adds minimal complexity to the rate matching process while significantly improving the consistency of retransmission performance, achieving a balance between ease of operation and reliability.
Data Source
AI summary
Methods and Apparatus for processing data encoded by low density parity check (LDPC) in a communication system are disclosed herein. In one embodiment, a method performed by a first node is disclosed. The method comprises: encoding an information bit sequence based on an LDPC coding scheme to obtain an encoded bit sequence; generating a master bit sequence based on the encoded bit sequence; selecting a subset of the master bit sequence according to a rate matching rule to obtain a rate matched bit sequence; interleaving the rate matched bit sequence according to a predetermined index sequence to obtain a to-be-transmitted bit sequence; and transmitting the to-be-transmitted bit sequence to a second node.