BICM Shaping Distribution Maintenance via Non-Shaping Bit Puncturing
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Solution Overview
Problem
The 5G NR coding scheme does not effectively combine shaping and coding, particularly when trying to implement bit-interleaved coded modulation (BICM), as it does not respect the shaping distribution, and puncturing systematic bits without care alters the target shaping distribution, making it difficult to achieve desired channel capacity.
Innovation Solution
A method that punctures non-shaping bits in a data transmitter to maintain the target shaping distribution, allowing for the implementation of a modified 5G NR coding scheme that respects the shaping performed by a distribution matcher, by puncturing systematic bits during rate matching and hybrid automatic repeat request (HARQ) processes without altering the target shaping distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If systematic bits are punctured in the 5G NR coding scheme, then the code rate is improved and transmission efficiency is increased, but the target shaping distribution is altered and channel capacity cannot be achieved
Solution Approach 1:
The patent segments the bit streams into shaping bits and non-shaping bits, allowing differential treatment during puncturing. Specifically, the coded bit sequence is divided into systematic shaping bits, systematic non-shaping bits, and parity bits. Only non-shaping bits are punctured while shaping bits are preserved, thus maintaining the shaping distribution while achieving rate matching.
Solution Approach 2:
The patent applies different quality requirements to different parts of the bit sequence. Shaping bits, which carry the non-uniform distribution information, are protected from puncturing to maintain local quality of the shaping distribution. Non-shaping bits, which carry uniform distribution information, are allowed to be punctured to achieve rate matching. This local differentiation resolves the contradiction between maintaining shaping accuracy and improving transmission efficiency.
2Reliability
If shaping and coding are combined using BICM scheme, then error correction capability is improved, but the implementation complexity increases and the 5G NR standard cannot be directly applied
Solution Approach 1:
The patent merges shaping and coding operations into a unified BICM framework. The distribution matcher generates shaped symbols from non-uniformly distributed bits, which are then encoded using 5G NR LDPC codes. The merging is achieved by processing shaping bits and non-shaping bits through the same coding pipeline with minor modifications, allowing error correction to protect both shaping information and data while maintaining standard compatibility.
Solution Approach 2:
The patent introduces dynamic rate matching by allowing flexible puncturing of non-shaping bits based on channel conditions and required code rates. The number of non-shaping bits to be punctured can be dynamically adjusted without affecting the shaping distribution, enabling adaptive modulation and coding while preserving the benefits of shaping.
3Ease of operation
If each symbol of the constellation is transmitted with equal probability, then the transmission process is simplified, but the channel capacity cannot be reached
Solution Approach 1:
The patent applies preliminary shaping action before transmission by using a distribution matcher to generate non-uniformly distributed bits from uniformly distributed source bits. This preliminary transformation creates the desired shaping distribution at the input of the channel encoder, enabling capacity-achieving transmission while keeping the actual transmission process simple through standard BICM operations.
Data Source
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AI summary
The invention relates to a method for transmitting symbols. A first signal, comprising a bit sequence representing a first data flow and a second data flow, is obtained. The first data flow comprises shaping bits. The second data flow comprises non-shaping bits, including quantification bits and/or a sign bit. At least part of the non-shaping bits of the second data flow are punctured, thusly obtaining incomplete bit streams. The symbols are obtained based at least on the incomplete bit streams and on the first data flow. The invention further relates to a corresponding data transmitter and to a corresponding computer program.