Signal Processing Apparatus for Peak-to-Average Power Ratio Reduction
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Solution Overview
Problem
Current signal transmission technologies face challenges in reducing peak-to-average power ratio (PAR) effectively, particularly in mobile communication systems, where higher order modulations require higher signal-to-noise ratios, and existing Crest Factor Reduction (CFR) algorithms introduce noise that needs to be balanced across carriers and resource blocks.
Innovation Solution
The proposed solution involves an apparatus and method that modify signals by generating a clipping pulse signal, converting it into narrowband signals, and controlling noise distribution using filter weights to achieve a desired error vector magnitude (EVM) or clipping noise distribution, which reduces the peak-to-average power ratio by preferentially distributing noise outside carriers, within guard bands, or among unused resource blocks, thereby optimizing noise levels for different modulation orders and MIMO ranks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Crest Factor Reduction (CFR) algorithms are used to reduce peak-to-average power ratio, then power consumption is reduced, but noise is introduced that degrades signal quality
Solution Approach 1:
The patent applies local quality by distributing clipping noise non-uniformly across different resource blocks and carriers. Filter weights are assigned to different frequency slices to control where noise is added, preferentially placing noise in resource blocks with lower modulation orders or in guard bands rather than uniformly across all resources. This allows local optimization of noise distribution to minimize overall signal quality degradation.
Solution Approach 2:
The patent changes parameters by dynamically adjusting filter weights based on modulation order, code rate, and MIMO rank of different resource blocks. The system modifies the noise distribution parameters adaptively, assigning different weight values to different frequency slices depending on their tolerance to noise, thereby optimizing the trade-off between PAR reduction and signal quality preservation.
2Productivity
If higher order modulations are used to increase data rate, then throughput is improved, but higher signal-to-noise ratio is required which increases power consumption
Solution Approach 1:
The patent enables local quality optimization by allowing different resource blocks to support different modulation orders based on their noise characteristics. High modulation orders (e.g., 256-QAM, 1024-QAM) can be used in resource blocks with low noise or high filter weights, while lower modulation orders are used in blocks with higher noise exposure. This allows the system to achieve high overall data rates without requiring all resources to support the highest modulation orders, thereby reducing power consumption.
3Device complexity
If clipping noise is distributed uniformly across all carriers, then implementation is simple, but signal quality degrades in high modulation order resource blocks
Solution Approach 1:
The patent implements local quality by assigning different filter weights to different frequency slices and resource blocks. Instead of uniform noise distribution, the system preferentially distributes clipping noise to resource blocks with lower modulation orders or in guard bands, while protecting resource blocks with high modulation orders from excessive noise. This selective noise distribution significantly reduces signal quality degradation in critical high-order modulation resources.
Solution Approach 2:
The system employs feedback mechanisms where the network determines desired EVM distribution and clipping noise distribution based on channel conditions, modulation schemes, and code rates. This feedback information is used to adjust filter weights dynamically, ensuring that noise is distributed in a way that maintains signal quality for high-order modulations while still achieving effective PAR reduction.
Data Source
AI summary
An apparatus, method and computer program is described comprising: receiving a first signal comprising one or more carrier signals comprising a plurality of resource blocks, wherein each resource block is assigned to a unique frequency and time slot of the respective carrier signal; generating a clipping pulse by modifying said first signal; converting the clipping pulse signal into a plurality of narrowband signals, wherein each narrowband signal is a frequency slice of the clipping pulse signal; modifying the plurality of narrowband signals to generate a plurality of modified narrowband signals, wherein said modifying is controlled based on filter weights that define a level of noise to be added to the respective narrowband signals in accordance with a desired error vector magnitude distribution or clipping noise distribution.