Polar Code Assistant Bit Allocation for Lower-Complexity Decoding
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Solution Overview
Problem
Polar codes in wireless communications face challenges in achieving efficient decoding due to impractical code lengths and channel capacity limitations, particularly in 5G New Radio (NR) applications, where existing decoding methods like SC and SCL decoding become complex and inefficient as code word length increases.
Innovation Solution
The proposed solution involves an apparatus and method for encoding and transmitting input bits using a sub-channel selector to allocate decoding assistant bits across non-adjacent segments with varying reliabilities, allowing for efficient encoding and transmission of code words, which assists in improving decoding performance by distributing assistant bits effectively across sub-channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SC or SCL decoding methods are used for polar codes, then decoding can be performed, but decoding complexity increases significantly as code word length increases
Solution Approach 1:
The code word is divided into multiple segments, each containing information bits and assistant bits. The decoding process is segmented into multiple stages, where each stage decodes one segment using soft information from previous stages. This segmentation reduces the overall decoding complexity by breaking down the large-scale decoding problem into smaller, more manageable sub-problems.
Solution Approach 2:
Assistant bits are inserted into each segment before decoding to provide preliminary error detection and correction capability. These assistant bits perform preliminary actions to simplify the main information bit decoding process, reducing the computational burden on the primary decoder by pre-processing error correction tasks.
2Reliability
If code length is increased to approach channel capacity, then error correction capability improves, but decoding efficiency decreases
Solution Approach 1:
By segmenting the long code word into smaller segments with assistant bits, the patent enables efficient decoding of long codes without requiring exponentially increasing computational resources. Each segment can be decoded independently with reduced complexity, maintaining productivity while achieving high error correction capability through the combined effect of multiple segments.
Solution Approach 2:
The patent changes the structural parameters of the code by inserting assistant bits at specific positions within segments. This parameter change transforms the decoding problem from an intractable large-scale problem into a series of smaller problems, improving decoding efficiency while maintaining the ability to correct errors in long code words.
3Reliability
If assistant bits are distributed across sub-channels, then decoding performance improves, but sub-channel allocation complexity increases
Solution Approach 1:
The patent segments the sub-channels into multiple groups, with each group associated with a specific segment of the code word. Assistant bits are allocated to specific sub-channel groups based on segment requirements, simplifying the allocation process by breaking down the complex global allocation problem into smaller, localized allocation decisions.
Solution Approach 2:
Different sub-channel allocation strategies are applied to different segments based on their specific requirements. Each segment receives assistant bits allocated according to its local characteristics and error probability, rather than applying a uniform allocation strategy across all sub-channels. This local quality approach optimizes decoding performance while reducing overall allocation complexity.
Data Source
AI summary
An assistant sub-channel to carry a decoding assistant bit, in input bits that are to be encoded, is selected from each of a plurality of non-adjacent segments. Each segment includes a subset of sub-channels with associated reliabilities. Some embodiments also involve grouping the sub-channels into the segments. After a target number of assistant sub-channels have been selected, the input bits are encoded to generate a codeword, and the codeword is transmitted. Assistant sub-channel selection could involve iterations to select assistant sub-channels at each iteration, until at least the target number of assistant sub-channels have been selected.