Dynamic Bit Allocation for HARQ Retransmission Throughput
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Solution Overview
Problem
In hybrid automatic repeat request (HARQ) schemes, particularly in OFDM and MIMO systems, the traditional bit allocation and interleaving methods do not effectively utilize bit significance during retransmissions, leading to suboptimal performance due to the mapping of high-significance coded bits to low-reliability positions.
Innovation Solution
A method and transmitter system that dynamically allocates and rearranges coded bits across groups based on significance and reliability levels, using a bit allocation controller and intra-symbol and inter-symbol interleavers to change the sequence of coded bits during retransmissions, optimizing bit mapping for improved throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional bit allocation and interleaving methods are used in HARQ schemes, then the system structure remains simple and easy to implement, but high-significance coded bits are mapped to low-reliability positions leading to suboptimal throughput performance
Solution Approach 1:
The patent implements dynamic bit allocation that adapts based on transmission type (initial transmission vs. retransmission) and HARQ scheme type (Type-I or Type-II). The bit allocation controller dynamically determines which coded bits to allocate to which bit positions based on current transmission conditions, allowing the system to optimize throughput performance while managing complexity through structured decision-making
Solution Approach 2:
The patent applies different bit allocation strategies to different groups of coded bits based on their significance. High-significance bits (such as systematic bits in Type-I HARQ or previously transmitted coded bits in Type-II HARQ) are allocated to high-reliability bit positions, while other bits are allocated to remaining positions. This localized optimization ensures that critical bits receive enhanced protection without unnecessarily complicating the entire system
2Reliability
If coded bits are consistently mapped to the same bit positions across retransmissions, then the implementation is straightforward, but error correction performance deteriorates due to repeated mapping of high-significance bits to low-reliability positions
Solution Approach 1:
The patent employs periodic retransmission strategies where the bit allocation pattern changes between initial transmission and retransmissions. For Type-II HARQ, the system alternates between transmitting different sets of coded bits in initial transmissions versus retransmissions, creating a periodic structure that improves error correction by varying which bits occupy which positions across transmission cycles
Solution Approach 2:
The patent performs preliminary identification and classification of coded bits by significance level before the actual mapping process. The bit allocation controller pre-determines which coded bits are high-significance (systematic bits, previously transmitted bits) and allocates them to high-reliability positions in advance, ensuring optimal error correction performance from the start of each transmission
Data Source
AI summary
A method for transmitting data represented by a plurality of coded bits includes: allocating the coded bits to a plurality of groups; rearranging, for a retransmission of the coded bits, ones of the coded bits allocated to a first one of the plurality of groups to a second one of the plurality of groups, and ones of the coded bits allocated to the second one of the plurality of groups to the first one or a third one of the plurality of groups; and changing, for the retransmission, a sequence of coded bits allocated to each of the plurality of groups after the rearranging.