SCL Decoder Buffer Updates for Low-Latency Path Sorting
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Solution Overview
Problem
Current Polar Code Successive Cancellation List (SCL) decoders face inefficiencies due to high latency in data exchange between processor stages, which affects their operational complexity and bit error performance, especially at longer block sizes.
Innovation Solution
The proposed solution involves selective replacement and deferred update techniques in buffer management, where only changed LLR statistics are updated, and in-place calculation of bit estimates are performed, reducing the need for extensive data copying and sorting, thereby minimizing latency and improving computational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional buffer management updates entire rows based on path metrics, then path metric accuracy is maintained, but data transfer overhead and latency increase significantly
Solution Approach 1:
The patent extracts and updates only the changed LLR statistics portions rather than entire rows. The buffer management identifies and updates only the specific statistics that have changed since the previous update cycle, removing the unnecessary data transfer overhead of copying entire rows while maintaining path metric accuracy.
Solution Approach 2:
The patent segments the buffer update operation into selective portions. Instead of treating each row as an indivisible unit that must be copied entirely, the update mechanism is segmented to modify only the specific LLR statistics that have changed, reducing data transfer latency while preserving accuracy.
2Productivity
If in-place calculation is used for bit estimate updates, then data copying overhead is reduced, but buffer management complexity increases
Solution Approach 1:
The patent inverts the conventional approach by performing in-place calculation of bit estimate updates directly in the buffer rather than calculating updates separately and then copying data. This reversal eliminates the need for extensive data copying and intermediate buffers, improving computational efficiency while the structured in-place update mechanism manages the complexity.
3Measurement precision
If extensive sorting and data copying is performed, then path metric accuracy is maintained, but processing bottlenecks increase
Solution Approach 1:
The patent extracts only the necessary path metric information that has changed and updates only those specific portions in the buffer. This selective extraction and update approach maintains path metric accuracy while eliminating the processing bottlenecks associated with sorting and copying entire rows of data.
Data Source
AI summary
Various embodiments are described of a system and method for improved SCL decoder operation. In particular, various embodiments are described which improve the efficiency of the buffer management based on updated path metric statistics. In some embodiments, the SCL decoder may perform selective replacement to limit the extent of LLR updates per row only to the statistics that have changed since the previous update cycle. In some embodiments, the SCL decoder may perform deferred updates, which may involves in-place calculation of both ûφ=0 and ûφ=1 bit estimate (LLR) updates based on the row from which the updated row will be derived.