HARQ Retransmission Using Non-Gaussian Interference Models
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Solution Overview
Problem
Current wireless communication systems, particularly those using the LTE standard, face performance degradation due to inter-cell interference (ICI) affecting reference signals, which is not adequately addressed by existing retransmission schemes in HARQ, leading to suboptimal channel decoding and reliability in OFDMA-based networks.
Innovation Solution
The proposed solution involves a method and apparatus for transmitting and receiving signals in a wireless communication system that considers interference characteristics and resource element grouping to optimize retransmissions in HARQ schemes, using feedback information to adjust retransmission strategies based on the reception scheme and interference patterns, thereby improving signal reliability and decoding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power boosting is applied to reference signals to reduce distortion from inter-cell interference, then reference signal reliability is improved, but non-Gaussian interference characteristics are introduced that degrade channel decoding performance
Solution Approach 1:
The patent changes the statistical model parameter from Gaussian to non-Gaussian (specifically using alpha-stable distribution with parameter alpha < 2) to match the actual interference characteristics caused by power-boosted reference signals. This allows the Log-Likelihood Ratio calculation to accurately reflect the interference environment, resolving the contradiction by adapting the mathematical model to the physical reality rather than forcing the physical system to conform to the mathematical model.
2Device complexity
If conventional HARQ retransmission schemes are used, then system complexity is maintained at acceptable levels, but decoding performance significantly degrades in the presence of power-boosted reference signal interference
Solution Approach 1:
The patent modifies only the statistical distribution parameter (using alpha-stable distribution instead of Gaussian distribution) in the Log-Likelihood Ratio calculation while keeping the overall HARQ framework intact. This minimal parameter change approach maintains system complexity at acceptable levels while significantly improving decoding performance in the presence of non-Gaussian interference from power-boosted reference signals.
3Power
If reference signals are power boosted to overcome inter-cell interference, then signal-to-noise ratio is improved, but the resulting non-Gaussian interference degrades log-likelihood ratio accuracy
Solution Approach 1:
The patent changes the statistical model parameter from Gaussian (alpha=2) to non-Gaussian (alpha<2) to match the interference characteristics. This allows the Log-Likelihood Ratio calculation to accurately measure signal quality despite the non-Gaussian interference environment created by power-boosted reference signals, thereby restoring measurement precision without reducing signal power.
Data Source
AI summary
The present disclosure relates to a pre-5th-generation (5G) or 5G communication system to be provided for supporting higher data rates beyond 4th-generation (4G) communication system such as a long term evolution (LTE). A method for transmitting a signal in transmitting apparatus in a wireless communication system supporting a hybrid automatic repeat request (HARQ) scheme is provided. The method includes transmitting a signal to a receiving apparatus; detecting there is a need for a retransmission operation for the signal; and performing the retransmission operation for the signal based on at least one of a reception scheme used in the receiving apparatus or an interference characteristic of an interference signal.