HARQ Retransmission Coding with Vertical Parity Check Blocks
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Solution Overview
Problem
In wireless communication systems, existing Hybrid Automatic Repeat Request (HARQ) technologies face inefficiencies due to the need to retransmit additional bits for all code blocks, even if only some are in error, leading to unnecessary resource usage and inefficient feedback mechanisms.
Innovation Solution
The system employs vertical check blocks determined from columns of horizontal code blocks, allowing for improved log likelihood ratios and simplified feedback, enabling retransmissions without knowing which code blocks are in error, and using interleaving to reduce the transmission of correctly known bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If incremental redundancy bits are retransmitted for all code blocks, then decoding reliability is improved, but transmission efficiency deteriorates due to unnecessary retransmissions
Solution Approach 1:
The invention segments the code blocks into code block groups (CBGs) and processes them independently. Each CBG is assigned a separate identifier, allowing the receiver to identify and feedback only the specific groups that contain erroneous code blocks. This segmentation enables selective retransmission of only the problematic groups rather than retransmitting all code blocks, thereby improving transmission efficiency while maintaining decoding reliability.
2Productivity
If code block group indexing feedback is implemented, then retransmission efficiency is improved, but feedback complexity increases
Solution Approach 1:
The invention makes the code block group identifier serve multiple functions: it acts as both a grouping mechanism for organizing code blocks and as a feedback signal for indicating which groups contain errors. This multi-functionality eliminates the need for separate feedback mechanisms, reducing overall system complexity while maintaining retransmission efficiency.
3Productivity
If outer codes are used for error correction, then retransmission overhead is reduced, but error correction capability deteriorates when multiple code blocks fail
Solution Approach 1:
The invention combines inner codes (such as Turbo codes or LDPC codes) for initial error correction with outer codes (such as Reed-Solomon codes or BCH codes) for additional protection. This composite coding approach leverages the strengths of both coding schemes: the inner codes provide robust correction for single errors while the outer codes provide additional protection against multiple errors, achieving both low retransmission overhead and high error correction capability.
Data Source
AI summary
Systems and methods are disclosed for providing H-ARQ transmissions in respect of a set of horizontal code blocks are combined in a code. Retransmissions contain vertical parity check blocks which are determined from verticals from the set of horizontal code blocks. Once all the vertical parity check blocks have been transmitted, a new set may be determined after performing interleaving upon either the content of the horizontal code blocks, in the case of non-systematic horizontal code blocks, or over the content of encoder input bits in the place of systematic horizontal code blocks. The interleaving may be bitwise or bit subset-wise. The retransmissions do not contain any of the original bits. In the decoder, soft decisions are produced, and nothing needs to be discarded; decoding will typically improve with each retransmission.