Adaptive FIR Precoding Tap Length for PAPR and Distortion Control
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Solution Overview
Problem
In single-carrier systems using FIR filters for precoding, fixed tap lengths lead to issues with peak-to-average power ratio (PAPR) and non-linear distortion due to varying channel states, affecting communication quality.
Innovation Solution
A wireless communication method and system that dynamically adjusts the tap length in FIR precoding based on feedback from the reception device, using a threshold value to control transmission power and minimize distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed tap length M is used in precoding, then the device complexity is reduced, but the communication quality deteriorates when channel state varies
Solution Approach 1:
The patent applies dynamics by making the tap length of the FIR filter variable rather than fixed. The tap length is dynamically adjusted based on channel conditions and the magnitude of tap coefficients. When channel state varies, the system can increase tap length to maintain communication quality, and when channel conditions are good, it can reduce tap length to lower complexity.
Solution Approach 2:
The patent changes the parameter of tap length from a fixed value to a variable parameter that adapts to channel conditions. By monitoring the magnitude of tap coefficients and channel state, the system adjusts the tap length parameter to optimize the balance between communication quality and device complexity in real-time.
2Reliability
If tap length is increased to handle large tap coefficients, then inter-stream interference is reduced, but PAPR increases causing non-linear distortion
Solution Approach 1:
The patent uses dynamics to adjust tap length based on the actual magnitude of tap coefficients. Instead of using a consistently long tap length, the system dynamically extends tap length only when necessary (when tap coefficients are large) and reduces it when tap coefficients are small, thereby suppressing inter-stream interference only when needed while avoiding unnecessary PAPR increase.
Solution Approach 2:
The patent changes the tap length parameter adaptively based on the statistical properties of channel coefficients. By monitoring coefficient magnitudes and adjusting tap length accordingly, the system optimizes the trade-off between interference suppression and PAPR control, preventing non-linear distortion while maintaining communication reliability.
3Object-generated harmful factors
If tap length is decreased to reduce PAPR, then non-linear distortion is reduced, but inter-stream interference increases
Solution Approach 1:
The patent applies dynamics by making tap length adaptive rather than static. The system continuously monitors channel conditions and tap coefficient magnitudes, adjusting tap length in real-time to maintain optimal performance. This dynamic adjustment ensures that inter-stream interference is suppressed when channel conditions require it, while avoiding excessive tap length that would cause non-linear distortion.
Solution Approach 2:
The patent changes the tap length parameter based on channel state information and coefficient statistics. By adaptively adjusting this parameter, the system achieves the optimal balance between reducing non-linear distortion and suppressing inter-stream interference, rather than being constrained by a fixed tap length that cannot adapt to varying channel conditions.
Data Source
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AI summary
A wireless communication method according to an embodiment includes a precoding step of precoding a stream of a transmission signal in a time domain by using an FIR filter, a transmission power control step of controlling a transmission power of the precoded stream, an amplification step of amplifying the precoded stream such that the controlled transmission power is obtained; and a tap length control step of performing control for changing a tap length in the precoding step such that the tap length is decreased in a case where a magnitude of a last tap coefficient in the precoding step is small and the tap length is increased in a case where the magnitude is large, with respect to a threshold value calculated on the basis of quality information of a received signal fed back from a reception device that has received the amplified stream or quality information of a received signal calculated by using at least characteristics of an amplification unit.