LDPC Circular Buffer Rate Matching for HARQ Decoding Reliability
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Solution Overview
Problem
Existing rate matching methods in wireless communications systems, particularly in 5G mobile communications, result in poor Hybrid Automatic Repeat Request (HARQ) performance due to inefficient bit puncturing and repetition strategies for Low-Density Parity-Check (LDPC) codes, leading to suboptimal decoding performance and increased errors in data transmission.
Innovation Solution
The proposed method optimizes the selection of starting positions for output bit sequences in a circular buffer to improve decoding performance by adjusting the distribution of starting positions for retransmissions, ensuring reduced redundancy and skipped bits, thereby enhancing the reliability of HARQ operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing rate matching method is used, then implementation is simple, but HARQ performance is poor
Solution Approach 1:
The patent changes the parameter of starting position selection in rate matching from fixed/existing methods to optimized positions determined by decoding performance requirements. Specifically, it selects starting positions that minimize repeated and skipped bits in the circular buffer, thereby improving HARQ performance without fundamentally changing the rate matching mechanism complexity
Solution Approach 2:
The patent introduces dynamic adaptation in rate matching by adjusting starting positions based on decoding performance and transmission conditions. The starting positions are no longer static but are dynamically selected to optimize the distribution of bits in the circular buffer, reducing redundancy while maintaining implementation feasibility
2Productivity
If bit puncturing is performed to increase code rate, then code rate increases, but decoding performance deteriorates
Solution Approach 1:
The patent applies local quality optimization by selectively puncturing bits at specific positions in the circular buffer rather than uniformly puncturing. It identifies and protects critical bits (those least likely to be repeated or skipped) while allowing puncturing of less critical bits, thereby maintaining decoding performance while achieving the desired code rate
Solution Approach 2:
The patent performs preliminary selection of starting positions before rate matching to ensure that bit puncturing occurs at optimal locations. By pre-determining which positions should be starting points and which can be punctured, it prevents deterioration of decoding performance while achieving the required code rate adjustment
3Reliability
If bit repetition is performed to decrease code rate, then code rate decreases, but redundancy increases
Solution Approach 1:
The patent optimizes the parameter of repetition positioning by selecting starting positions that minimize redundant bit repetition. Instead of repeating bits at any position, it strategically chooses starting positions that ensure repeated bits are those most beneficial for decoding, thereby reducing unnecessary redundancy while maintaining the decreased code rate
4Reliability
If starting positions are not optimized, then implementation is straightforward, but repeated and skipped bits increase
Solution Approach 1:
The patent optimizes the starting position parameter by selecting positions that minimize repeated and skipped bits in the circular buffer. It changes from using default or fixed starting positions to using optimized positions determined by analyzing bit distribution and decoding requirements, thereby improving reliability while keeping the selection process manageable
Data Source
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AI summary
This application discloses a method and an apparatus for processing information, a communications device, and a communications system. The communications device is configured to obtain a starting position of an output bit sequence in a coded block in a circular buffer, and determine the output bit sequence in the coded block based on a length of the output bit sequence and the starting position. A value of the starting position is one of {p0, p1, p2..., pkmax-1}, where 0 ≤ pk < NCB, pk is an integer, k is an integer, 0 ≤ k < kmax, NCB is a size of the coded block, and kmax is an integer greater than or equal to 4. Because a bit sequence for an initial transmission or a retransmission is properly determined, decoding performance of a communications device at a receive end after receiving the bit sequence is improved, a decoding success rate is improved, and a quantity of retransmissions is further reduced.