Spectrum Shaping Filter Adaptation for Cellular PAPR Reduction
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Solution Overview
Problem
In cellular communication networks, especially in multicarrier systems, the Peak-to-Average Power Ratio (PAPR) can be high due to out-of-phase sub-carriers, leading to peak power reduction and transmission power limitations, which is a challenge for networks like LTE and 5G, where spectral shaping is needed to enhance performance.
Innovation Solution
The method involves determining and applying spectrum flatness requirements based on frequency domain resource allocations, such as the size and location of Physical Resource Blocks (PRBs), to optimize spectral shaping and reduce PAPR, ensuring good system performance even with small resource allocations by adjusting the maximum allowed ripple according to the resource allocation size and location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If spectral shaping is applied to reduce PAPR, then transmission power can be increased, but detection loss occurs in small resource allocations
Solution Approach 1:
The patent applies different spectral shaping filter characteristics to different resource allocation sizes. For small resource allocations (first size threshold or below), a first set of filter characteristics is used that prioritizes receiver performance. For large resource allocations (above threshold), a second set of filter characteristics is used that prioritizes PAPR reduction. This local differentiation resolves the contradiction by adapting the spectral shaping aggressiveness to the specific allocation size context.
Solution Approach 2:
The patent dynamically selects spectral shaping filter characteristics based on the resource allocation size parameter. The network node determines the appropriate filter characteristics from multiple available sets according to the actual resource allocation granted to the user equipment. This dynamic adaptation allows the system to optimize between PAPR reduction and receiver performance based on real-time conditions.
2Power
If aggressive spectral shaping is used to maximize PAPR reduction, then transmission power increases, but system performance degrades for small resource allocations
Solution Approach 1:
Different spectral shaping filter characteristics are applied locally based on resource allocation size. For small allocations, less aggressive filtering maintains system performance. For large allocations, more aggressive filtering maximizes PAPR reduction. This resolves the contradiction by making the spectral shaping intensity dependent on the specific operational context.
3Device complexity
If uniform spectral shaping requirements are applied to all resource allocations, then implementation is simplified, but performance is suboptimal for different allocation sizes
Solution Approach 1:
The patent implements dynamic spectral shaping where the filter characteristics are selected based on the resource allocation size. The network node receives an indicator from the UE about supported filter characteristics and selects the appropriate set based on the granted resources. This dynamic approach optimizes spectral efficiency for different allocation sizes while maintaining manageable implementation complexity through standardized filter characteristic sets.
Data Source
AI summary
According to an example aspect of the present invention, there is provided a method, comprising, receiving, by a user equipment, a resource allocation from a wireless network node, for transmission of at least one signal, wherein the resource allocation comprises at least a frequency domain resource allocation, determining, by the user equipment, at least one spectrum flatness requirement based at least on the frequency domain resource allocation and transmitting, by the user equipment, the at least one signal to the wireless network node according to the at least one spectrum flatness requirement.