5G NR LDPC Demodulation With Noise-Aware Channel Normalization
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Solution Overview
Problem
In 5G new radio (NR) channels, certain bandwidth portions are left blank without a reference sequence for channel estimation, leading to noise amplification during demodulation due to normalization by channel power alone, which is inefficient and can cause decoding failures, especially in low channel power conditions.
Innovation Solution
The method involves performing Fast Fourier Transform, determining the presence of a reference sequence, and demodulating OFDM symbols using the formula r bin * conj(H bin )/(norm(H bin )^2 + Noise_Power), which includes noise power estimation to prevent noise amplification, and using this approach for LDPC decoding to ensure accurate data recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If normalization is done by channel power alone (zero-forcing equalizer), then the number of bits needed to represent log-likelihood ratio is minimized, but noise gets amplified when channel power is low
Solution Approach 1:
The patent changes the normalization parameter from channel power alone to the sum of channel power and noise power. This parameter modification prevents noise amplification while maintaining efficient bit representation for log-likelihood ratio, resolving the contradiction between minimizing bit quantity and preventing noise amplification.
2Object-affected harmful factors
If noise power is added to channel power for normalization (MMSE equalizer), then noise amplification is prevented, but when channel power is high the scaling effect is minimal
Solution Approach 1:
The patent implements dynamic normalization where the scaling factor adapts based on the relative magnitudes of channel power and noise power. When channel power is low, noise power provides significant scaling to prevent amplification; when channel power is high, the scaling effect is naturally minimal. This dynamic approach maintains both noise prevention and decoding efficiency.
3Measurement precision
If FFT/IFFT gains are adjusted for different platforms, then noise power estimation accuracy is improved, but device complexity and implementation variability increase
Solution Approach 1:
The patent enables the system to self-calibrate noise power estimation by using actual received signals and channel estimates from each specific platform. Instead of requiring pre-configured platform-specific FFT gain values, the system automatically adapts to each implementation's characteristics through empirical measurement and adjustment, reducing device complexity while maintaining precision.
Data Source
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AI summary
A system and method for 5G new radio (NR) low-density low density parity check (LDPC) decoding comprising performing a Fast Fourier Transform using a Fast Fourier Transform algorithm. The system and method determines if a reference sequence is present and performing a channel estimate and a channel interpolate for the channel estimate if the reference sequence is present. The system and method demodulates at least one orthogonal frequency division multiplexing (OFDM) symbol according to rbin * conj(Hbin)/(norm(Hbin)2 + Noise_Power). The system and method decodes the demodulated at least one orthogonal frequency division multiplexing symbol, and determines if the decoded at least one orthogonal frequency division multiplexing symbol is correct.