Signal Spreading and Multiplexing Using Two-Level FEC Coding
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Solution Overview
Problem
Conventional CDMA encoding methods provide high coding rates but struggle to meet the increasing demands of next-generation wireless networks for higher coding rates while maintaining transmission flexibility and robustness against network impairments.
Innovation Solution
Implementing a two-level FEC encoding process involving binary and non-binary FEC codes, combined with sparse spreading and user-specific signal processing operations, to enhance signal spreading and multi-user signal multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CDMA encoding is used, then high coding rates are achieved, but the system cannot meet the increasing demands for even higher coding rates in next-generation wireless networks
Solution Approach 1:
The patent divides the single encoding stage into two sequential stages: first a binary FEC encoder processes the input bits to generate coded bits, then a non-binary FEC encoder processes these coded bits to generate final codewords. This segmentation allows each encoder to operate at optimal rates, achieving overall higher coding rates while maintaining the flexibility needed for next-generation wireless networks.
2Reliability
If signal spreading is performed to achieve higher diversity and robustness, then reliability improves, but system complexity increases
Solution Approach 1:
The patent extends the spreading operation from traditional time-domain or frequency-domain single dimensions to multiple dimensions by applying both binary and non-binary spreading sequences across different resource elements. This multi-dimensional spreading achieves higher diversity orders and robustness while the structured approach to multiple spreading layers helps manage system complexity through organized resource allocation.
3Reliability
If multiple FEC encoding levels are implemented, then reliability and robustness improve, but decoding complexity increases
Solution Approach 1:
The decoding process is segmented into two corresponding stages: first a binary FEC decoder processes the received signal to recover coded bits, then a non-binary FEC decoder processes these coded bits to recover the original information bits. This segmentation allows each decoder to use optimized algorithms appropriate for its specific code type, managing overall decoding complexity while maintaining the reliability benefits of dual-level FEC.
Solution Approach 2:
The binary FEC decoding is performed as a preliminary step before non-binary FEC decoding. This preliminary action reduces the complexity of the subsequent non-binary decoding by pre-processing the signal and eliminating some error sources early in the decoding chain, making the overall multi-level decoding process more manageable.
Data Source
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AI summary
Binary forward error correcting (FEC) encoding is applied to a stream of input bits, to generate a stream of coded bits. The coded bits are mapped to multiple binary streams. In some embodiments, at least one coded bit is mapped to more than one of the binary streams and none of the binary streams are identical to each other. Stream-specific modulations are applied to the binary streams. Non-binary FEC encoding could be applied after the stream-specific modulations.