LDPC Rate Matching with Variable Buffer Start Positions for HARQ
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Solution Overview
Problem
Current rate matching methods in wireless communications systems, particularly in 5G mobile communication, result in poor Hybrid Automatic Repeat Request (HARQ) performance when using Low-Density Parity-Check (LDPC) codes, leading to decoding performance issues due to repeated and skipped bits during retransmissions.
Innovation Solution
The method involves determining a starting position k0 in a buffer sequence for output bit sequences or soft bit sequences, optimizing the selection of bits to reduce repeated bits and improve decoding performance by adjusting the starting position based on specific intervals and code rates, thereby enhancing HARQ performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing rate matching method is used, then code rate adjustment is achieved, but HARQ performance deteriorates due to repeated and skipped bits
Solution Approach 1:
The patent changes the starting position parameter k0 dynamically based on the redundancy version index rv and code block index cb using the formula k0 = (rv × NCB / 8) + (cb × K / NCB), where NCB is the circular buffer length and K is the information bit length. This parameter transformation ensures that each retransmission starts from a different position in the circular buffer, distributing the selection across different bit sequences and reducing the occurrence of repeated and skipped bits, thereby improving HARQ performance
2Productivity
If bit puncturing or repetition is performed during rate matching, then code rate is adjusted, but decoding performance deteriorates
Solution Approach 1:
The patent performs preliminary organization of coded bits into a circular buffer structure before rate matching and retransmission. By pre-arranging bits in a circular buffer and selecting starting positions based on redundancy versions, the system prepares the bit sequence in advance to minimize repeated and skipped bits during HARQ operations, thereby maintaining decoding performance while achieving code rate adjustment
Data Source
AI summary
An information processing method, an apparatus, a communications device, and a communications system are provided. The communications device is configured to: obtain a starting position in a buffer sequence W for an output bit sequence, and determine the output bit sequence from the buffer sequence W based on the starting position, where a value of the starting position is one element in {p0, p1, p2, . . . , pk<sub2>max</sub2>−1}, 0≤k<kmax, 0≤pk<NCB, pk is an integer, k is an integer, NCB is a length of the buffer sequence W, kmax is an integer greater than or equal to 4, and there are two or more different neighboring intervals in {p0, p1, p2, . . . , pk<sub2>max</sub2>−1}. A bit sequence for initial transmission or retransmission is properly determined, so that decoding performance of a communications device on a receive end after receiving the bit sequence is improved, a decoding success rate is enhanced, and a quantity of retransmission times is further reduced.