Logarithm Domain Decoding for Non-Orthogonal Access
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Solution Overview
Problem
Existing decoding methods for non-orthogonal air interface access in LTE systems are complex and require high hardware complexity, limiting spectral efficiency and channel capacity.
Innovation Solution
A decoding method and apparatus that performs decoding in the logarithm domain, using initialization calculations and probability determination for codewords carried on multiple subcarriers, reducing algorithm complexity and hardware requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-orthogonal air interface access is implemented with multiple codewords superposed on one system resource block, then spectral efficiency and channel capacity are improved, but decoding complexity and hardware requirements increase significantly
Solution Approach 1:
The patent replaces the conventional maximum likelihood decoding approach with a message passing algorithm that operates in the logarithm domain. This substitution transforms the complex probabilistic calculations into simplified logarithmic operations, significantly reducing decoding complexity while maintaining the non-orthogonal multiple access capability that improves spectral efficiency
Solution Approach 2:
The patent changes the computational domain from linear probability space to logarithm space. By performing message passing operations in the logarithm domain, the algorithm simplifies complex multiplicative probability calculations into additive logarithmic operations, reducing hardware complexity while preserving the ability to decode multiple superposed codewords
2Quantity of substance
If multiple codewords are superposed on one system resource block for non-orthogonal transmission, then channel capacity is improved, but hardware requirements become excessively high
Solution Approach 1:
The patent substitutes the hardware-intensive maximum likelihood decoder with a message passing algorithm operating in logarithm domain. This replacement maintains the ability to handle multiple superposed codewords that increase channel capacity, while dramatically reducing the hardware complexity through simplified logarithmic computations instead of complex probabilistic calculations
3Reliability
If prior-art decoding methods are used for non-orthogonal air interface access, then decoding accuracy is maintained, but algorithm complexity and hardware requirements are excessively high
Solution Approach 1:
The patent transforms the decoding algorithm to operate in the logarithm domain rather than the conventional probability domain. This parameter change simplifies the mathematical operations from complex multiplicative probability calculations to additive logarithmic operations, reducing algorithm complexity while maintaining decoding accuracy through the message passing framework
Solution Approach 2:
The patent replaces the complex prior-art decoding algorithms with a message passing algorithm that operates in logarithm space. This substitution maintains decoding reliability by preserving the essential probabilistic relationships, while significantly reducing algorithm complexity through the use of simplified logarithmic operations
Data Source
AI summary
Embodiments of the present invention provide a decoding method and apparatus. The method includes: receiving K user signals by using N subcarriers, where one user signal is carried on at least two subcarriers of the N subcarriers, one subcarrier carries at least two user signals of the K user signals, and 2≤N<K; determining, from the N subcarriers, at least two target subcarriers that carry a target user signal, and performing initialization calculation on the target subcarriers, to obtain initialization calculation results; and determining, in a logarithm domain, a probability of each codeword in a codebook of the target user signal according to the initialization calculation results, to decode the target user signal. According to this method, decoding can be performed in the logarithm domain with low complexity.