Adaptive Clipping Ratio for OFDM PAPR Reduction
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Solution Overview
Problem
MIMO-OFDM communication systems face challenges with high peak-to-average power ratio (PAPR) leading to non-linear distortion and power efficiency deterioration, particularly due to high power amplifiers, which are exacerbated by interference levels such as inter-cell and inter-carrier interference.
Innovation Solution
A method that estimates interference levels in the communication channel, determines a clipping ratio to minimize clipping distortion power below interference power, and clips and filters the OFDM signal accordingly, using parameters like inter-user and inter-cell interference, energy efficiency, and error vector magnitude to optimize power amplifier efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a clipping scheme is used to reduce PAPR, then power amplifier efficiency is improved, but clipping distortion degrades overall system performance
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the clipping ratio (CR) based on interference level measurements. The system measures the actual interference level in the communication channel and selects an optimal CR value from a predetermined set, thereby changing the clipping parameter adaptively to balance PAPR reduction and distortion minimization
Solution Approach 2:
The patent implements feedback by measuring the interference level in the communication channel and using this measurement to determine the appropriate clipping ratio. The system continuously monitors interference and adjusts the CR accordingly, creating a closed-loop control mechanism that optimizes the clipping process based on actual channel conditions
2Power
If a fixed high clipping ratio is used, then PAPR is reduced and power amplifier efficiency improves, but system performance degrades due to increased clipping distortion
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed clipping ratio to a dynamic, adaptive clipping ratio that changes based on channel conditions. The system measures interference levels and adjusts the CR in real-time, making the clipping process adaptive rather than static, thereby optimizing both power efficiency and performance under varying conditions
Solution Approach 2:
The patent changes the clipping ratio parameter dynamically based on measured interference levels. Instead of using a fixed high CR that always reduces PAPR but causes distortion, the system selects CR values from a predetermined set based on actual channel conditions, optimizing the trade-off between power efficiency and system performance
3Productivity
If adaptive clipping ratio adjustment based on interference level is implemented, then both PAPR reduction and system performance are optimized, but device complexity increases
Solution Approach 1:
The patent applies partial action by implementing adaptive CR adjustment only to the extent necessary for optimization. The system uses a predetermined set of CR values rather than continuous adjustment, and selects from this finite set based on interference measurements, thereby achieving optimization without full complexity of continuous adaptive control
Solution Approach 2:
The patent uses a predetermined set of clipping ratio values that can be stored in memory and selected based on conditions. This approach replaces complex real-time calculation of optimal CR with simple lookup and selection from pre-computed values, reducing computational complexity while maintaining adaptive optimization
Data Source
AI summary
Methods and apparatus for reducing a peak-to-average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) signal in an MIMO-OFDM communication system is provided, in which the method for reducing the PAPR of the OFDM signal may identify interference generated in an MIMO communication system, and adjust a clipping ratio (CR) for an effect of a clipping distortion to be less than an effect of interference.