Crest Factor Reduction Shaping Filter Spectrum Management
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Solution Overview
Problem
Current wireless communication systems face challenges in managing spectrum to reduce crest factor reduction (CFR) distortion, which affects signal quality and efficiency.
Innovation Solution
The method involves applying crest factor reduction to an input signal by using a shaping filter that distributes CFR noise within a transmission frequency band and outside of it in designated air interface resources, and transmitting the output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crest factor reduction is applied to reduce signal distortion, then signal quality improves, but CFR noise interferes with adjacent frequency bands
Solution Approach 1:
The patent segments the frequency spectrum into transmission frequency band and adjacent frequency bands, and further segments CFR noise into in-band noise and out-of-band noise. By applying different handling strategies to different segments (shaping filter for in-band, nulling for out-of-band), the system resolves the contradiction between maintaining signal quality and reducing noise interference.
Solution Approach 2:
The patent extracts out-of-band CFR noise from the transmission signal using a nulling operation that removes the noise component in adjacent frequency bands. This extraction separates the harmful out-of-band noise from the useful transmission signal, allowing the system to maintain both signal quality and reduce adjacent band interference.
2Object-affected harmful factors
If spectrum resources are allocated for CFR noise, then noise interference is reduced, but available transmission resources decrease
Solution Approach 1:
The patent changes the spectral distribution parameters of CFR noise by applying a shaping filter that modifies the noise power spectral density. Instead of uniform noise distribution, the shaping filter concentrates in-band noise and pushes out-of-band noise to adjacent bands where it can be nulled, thereby reducing overall harmful interference without requiring additional spectrum resources.
3Reliability
If shaping filter is applied to distribute CFR noise, then in-band noise is reduced, but out-of-band noise increases
Solution Approach 1:
The patent introduces a nulling operation as an intermediary step between the shaping filter and the transmitted signal. The shaping filter first redistributes CFR noise spectrally, then the nulling operation acts as a mediator to remove the resulting out-of-band noise component before transmission, thereby achieving both in-band noise reduction and out-of-band interference control.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a network node may apply a crest factor reduction (CFR) to an input signal to generate an output signal, the applying the CFR to the input signal including applying a shaping filter that distributes a first portion of CFR noise within a transmission frequency band of the output signal and a second portion of the CFR noise in at least one air interface resource that is outside of the transmission frequency band of the output signal. The network node may transmit the output signal. Numerous other aspects are described.