2D-NUC Demapper Lookup Table for O(1) LLR Calculation
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Solution Overview
Problem
Current demappers for 2D-NUC in wireless devices face high complexity, especially at high data rates, which hinders efficient reception performance due to the need for complex LLR calculations.
Innovation Solution
The method involves using a zero-forcing or minimum mean squared error equalizer to reduce demapper complexity by pre-calculating and storing LLR values in a lookup table, allowing for efficient LLR calculation and reducing the computational burden.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of constellation symbols N is decreased to reduce demapper complexity, then the computational complexity is reduced, but the demapper performance deteriorates
Solution Approach 1:
The patent pre-calculates LLR values for all possible combinations of equalized input information and channel state information before actual reception. These pre-calculated values are stored in a lookup table, so during reception, the demapper only needs to perform table lookups rather than complex real-time calculations. This preliminary action resolves the contradiction by preparing the complexity-reducing data structure in advance, allowing O(1) complexity during operation while maintaining accurate LLR values for high performance.
Solution Approach 2:
The patent creates a lookup table that is a pre-computed copy of all possible LLR calculation results. Instead of performing complex calculations during reception, the system copies the appropriate pre-calculated LLR value from the lookup table based on the current input and channel state. This copying approach eliminates real-time computational complexity while preserving the accuracy of the LLR values, thus resolving the contradiction between complexity reduction and performance maintenance.
2Reliability
If 2D-NUC is used to achieve reception performance gain, then the error vector magnitude is reduced, but the demapper complexity increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-calculating all LLR values for 2D-NUC constellation points considering all possible channel state information combinations. These results are stored in a lookup table organized by equalized input information and channel state information. During actual reception, the demapper simply performs table lookups based on the current inputs, avoiding the need for complex real-time 2D-NUC LLR calculations while maintaining the reception performance gains of 2D-NUC.
Solution Approach 2:
The lookup table serves as an intermediary between the complex 2D-NUC demapping requirements and the simple reception operation. The lookup table pre-processes the complex relationships between 2D-NUC constellation points and channel states, storing the results in an easily accessible format. This intermediary structure allows the system to benefit from 2D-NUC performance without directly implementing complex 2D-NUC demapping algorithms in real-time.
3Reliability
If LLR calculation is performed in real-time with high precision, then the reception performance is maintained, but the computational complexity and processing time increase
Solution Approach 1:
The patent performs the time-consuming LLR calculations in advance during system initialization or setup phase, storing the results in a lookup table. During actual reception operations, the system only needs to perform fast table lookups rather than complex real-time calculations. This separates the time-consuming computation from the time-sensitive reception operation, maintaining high reception performance while minimizing processing time loss.
Solution Approach 2:
The system creates a static copy of all possible LLR calculation results in the lookup table. During reception, instead of recalculating LLR values in real-time, the system copies the appropriate pre-calculated value from the lookup table based on the current equalized input information and channel state information. This copying operation is much faster than real-time calculation, thus maintaining performance while reducing processing time.
Data Source
AI summary
A method for supporting a receiving operation based on 2D-NUC performed by a first wireless device according to the present embodiment, comprises the steps of: receiving first and second input information from a second wireless device; performing equalization on the first and second input information; and generating LLR information on the basis of lookup table information predetermined for the equalized first and second input information and 2D-NUC.