Wireless Transmitter FIR Precoding 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 non-linear 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 the magnitude of the last tap coefficient and channel conditions, allowing the precoding filter to adapt to varying channel states while maintaining manageable complexity through controlled adjustment rules
2Power
If the tap length is decreased when the last tap coefficient magnitude is small, then the PAPR is reduced, but the communication quality may deteriorate due to insufficient precoding
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the tap length parameter based on the magnitude of the last tap coefficient. When the coefficient magnitude is below a threshold, the tap length is reduced to lower PAPR; when above the threshold, the tap length is maintained or increased to preserve precoding effectiveness, thus adapting the system parameter to current channel conditions
3Reliability
If the tap length is increased when the last tap coefficient magnitude is large, then the precoding effectiveness is improved, but the PAPR increases causing non-linear distortion
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the tap length based on the last tap coefficient magnitude. When the coefficient exceeds a threshold, the tap length is increased to improve precoding effectiveness and suppress interference; when below the threshold, the tap length is decreased to reduce PAPR and avoid non-linear distortion, thus adapting to channel conditions
4Ease of operation
If a fixed tap length is used, then the ease of operation is improved, but the adaptability to channel state variations deteriorates
Solution Approach 1:
The patent applies dynamics by transitioning from a static fixed tap length to a dynamic adjustable tap length. The system automatically adjusts the tap length based on channel state indicators (last tap coefficient magnitude), providing adaptability while maintaining ease of operation through automated control rules that require minimal manual configuration
Data Source
AI summary
A wireless communication method according to an embodiment includes precoding a stream of a transmission signal in a time domain by using an FIR filter, controlling a transmission power of the precoded stream, amplifying the precoded stream such that the controlled transmission power is obtained; and performing control for changing a tap length in precoding such that the tap length is decreased in a case where a magnitude of a last tap coefficient in precoding 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 amplifier.