LLR Quantization in Wireless Receivers Without Sample Collection
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Solution Overview
Problem
The existing wireless communication systems experience processing delays due to the need to collect sufficient samples of LLR values before quantization, which increases the processing time in LLR quantization.
Innovation Solution
A wireless communication system that calculates the variance of the log likelihood ratio based on channel information and uses this variance, along with the average value determined by the modulation scheme, to determine a statistical distribution for LLR quantization, allowing for immediate quantization without the need for sample collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sufficient samples of LLR values are collected before quantization, then the accuracy of statistical distribution determination is improved, but the processing delay increases
Solution Approach 1:
The patent pre-calculates and stores the relationship between signal-to-noise ratio (SNR) and the statistical distribution parameters (mean and variance) of LLR values. During actual operation, the system only needs to determine the current SNR and lookup the corresponding pre-computed distribution parameters, eliminating the need to collect sufficient LLR samples in real-time while maintaining accurate statistical distribution determination.
2Quantity of substance
If the number of quantization bits for LLR value is reduced, then the transmission amount between RRH and BBU is reduced, but the quantization error increases
Solution Approach 1:
The patent transforms the LLR quantization problem from fixed-bit quantization to adaptive quantization based on statistical distribution. By determining the mean and variance of LLR values and using these parameters to set quantization thresholds and levels, the system achieves optimal quantization performance with fewer bits. The quantization scheme adapts to the actual signal conditions, maintaining accuracy while reducing transmission overhead.
3Productivity
If LLR quantization is performed without sample collection, then the processing speed is improved, but the reliability of statistical distribution determination may deteriorate
Solution Approach 1:
The system pre-computes and stores the mapping between SNR values and the corresponding LLR statistical distribution parameters (mean and variance) across a range of possible conditions. During real-time operation, the system determines current SNR and retrieves the pre-computed parameters, achieving both high processing speed and reliable statistical distribution determination without needing to collect samples during the quantization process.
Data Source
AI summary
A wireless communication system includes an RF reception unit configured to receive a radio signal from a terminal; a channel estimation unit configured to estimate channel information of a wireless transmission path with respect to the terminal; a demodulation unit configured to perform soft decision demodulation on the radio signal; a quantization unit configured to quantize a log likelihood ratio obtained through soft decision demodulation in the demodulation unit, on the basis of a statistical distribution determined using an average value of the log likelihood ratio determined in accordance with a modulation scheme used in wireless communication with the terminal and a variance of a log likelihood ratio obtained on the basis of the channel information; and a decoding unit configured to perform a decoding process on the log likelihood ratio quantized by the quantization unit.