Modem Chip SIR-Based LLR Modes for Low-Complexity Decoding
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Solution Overview
Problem
The complexity of calculating log likelihood ratios (LLR) increases with higher modulation orders and number of layers in wireless communication systems, leading to performance degradation.
Innovation Solution
A modem chip that reduces LLR complexity by determining the number of constellation points based on the signal-to-interference ratio (SIR) and selecting appropriate LLR calculation modes, using a linear detection matrix when SIR is high and a K-detection mode when SIR is low.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the modulation order and number of layers are increased to improve decoding accuracy, then the performance of signal reception is improved, but the complexity of calculating log likelihood ratio increases
Solution Approach 1:
The patent applies dynamics by making the number of constellation points adaptive rather than fixed. The processor dynamically determines the number of constellation points based on the calculated signal-to-interference ratio (SIR), allowing the system to adjust between high accuracy modes (more constellation points) and low complexity modes (fewer constellation points) depending on channel conditions
Solution Approach 2:
The patent changes the parameter of constellation point quantity based on SIR conditions. When SIR is high, the system uses more constellation points for accurate LLR calculation. When SIR is low, the system reduces the number of constellation points to lower calculation complexity, thus resolving the contradiction between accuracy and complexity
2Reliability
If more constellation points are used to calculate LLR for high modulation orders, then decoding accuracy is improved, but calculation complexity and power consumption increase
Solution Approach 1:
The system dynamically adjusts the number of constellation points based on real-time SIR measurement. During good channel conditions (high SIR), the system uses more constellation points for accurate decoding. During poor channel conditions (low SIR), the system reduces constellation point quantity to lower power consumption, thus resolving the contradiction between accuracy and energy efficiency
3Device complexity
If the number of constellation points is reduced to lower LLR calculation complexity, then power consumption and calculation time are reduced, but decoding accuracy deteriorates
Solution Approach 1:
The patent changes the parameter of constellation point quantity adaptively. The processor calculates SIR and selects an appropriate number of constellation points from pre-configured sets based on SIR thresholds. This allows the system to use fewer constellation points (lower complexity) when channel conditions permit, while switching to more constellation points (higher accuracy) when needed, thus resolving the contradiction between complexity and accuracy
Data Source
AI summary
A modem chip includes a radio frequency integrated circuit (RFIC) configured to receive a signal including channel state information, and a processor configured to determine a signal to interference ratio (SIR) of the received signal based on the channel state information. The processor selects a log likelihood ratio (LLR) calculation mode among at least two LLR calculation modes that differently calculate an LLR of the received signal, by comparing the SIR with at least one threshold, and decodes the received signal by calculating the LLR of the received signal based on the selected LLR calculation mode.