Circular Buffer Start Positioning for LDPC HARQ Retransmissions
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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 suboptimal decoding performance 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 output bits to minimize 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 in the circular buffer for retransmission. By adjusting k0 to different values (e.g., k0=0 for initial transmission, k0=K for first retransmission, k0=2K for second retransmission), the system selects different portions of the coded bit sequence, thereby avoiding repeated and skipped bits and improving HARQ performance.
2Adaptability or versatility
If bit puncturing or repetition is performed during rate matching, then code rate is adjusted, but decoding performance deteriorates
Solution Approach 1:
The patent segments the coded bit sequence into multiple portions by using different starting positions k0 in the circular buffer. Each retransmission sends a different segment (e.g., first K bits, next K bits, etc.), allowing the receiver to combine diverse segments without excessive repetition, 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.