Sequential SCMA Detection Reducing Computational Complexity
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Solution Overview
Problem
Existing joint detection and decoding methods for SCMA signals face high computational complexity and burden due to iterative processes, which hinder achieving optimal bit error rate (BER) performance.
Innovation Solution
A sequential detection method and apparatus that selectively updates variable nodes based on the usage of function nodes, applying a weight to probability information, and performs channel decoding between function and variable node update processes to reduce complexity and iterative cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If joint detection and decoding is performed iteratively to improve BER performance, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the detection and decoding process into distinct stages: function node message updating, variable node message updating, and channel decoding. By separating these operations and performing them in a structured sequence rather than fully joint iteration, the computational complexity is reduced while maintaining BER performance through systematic message passing and probability updating.
2Reliability
If iterative detection and decoding is performed to obtain reliable estimation data, then reliability is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary message updating at function nodes before variable node updating, and conducts channel decoding at intermediate stages rather than waiting for complete iteration. This preliminary action structure allows reliable estimation data to be obtained earlier in the process, reducing the total number of iterative cycles required while maintaining data reliability.
3Device complexity
If sequential detection is performed for multiple users to reduce complexity, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent implements feedback mechanisms where detection results from earlier users and intermediate decoding results are fed back into the message passing process. The probability information and messages are continuously updated and refined through multiple passes, allowing sequential detection to achieve accuracy comparable to joint detection while maintaining lower computational complexity.
Data Source
AI summary
The present disclosure provides a method and apparatus for sequentially detecting and decoding multiuser sparse code multiple access (SCMA) signal. A detection method includes selecting a single variable node depending on how much the plurality of variable nodes each use function nodes that connect to updated variable nodes; updating messages passed to the single variable node, based on a function node input message passed to the plurality of function nodes and signals received by the plurality of function nodes through channels; mapping updated messages to a priori information of a channel decoder; inputting the priori information to the channel decoder and thereby obtaining probability information of a symbol for the single variable node; and updating messages passed from the single variable node to one of the plurality of function nodes by applying a weight to the probability information of the symbol for the single variable node.