EDGE Clipper Residual Filtering for Low-PAR Multicarrier Signals
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Solution Overview
Problem
Existing power amplifiers in mobile communication systems, such as EDGE systems, face inefficiencies due to high peak-to-mean amplitude ratios (PAR) in signals, which increase power consumption and require complex algorithms to reduce PAR, often compromising frequency and EVM requirements.
Innovation Solution
A method that generates a residual signal from a multicarrier signal by clipping it to a predetermined level, applies a least squares function to minimize the residual signal for each carrier, and combines it with the original signal, using complex filtering to meet frequency and EVM constraints, thereby reducing the peak-to-mean ratio without deteriorating time-domain properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If clipping algorithms are used to reduce PAR, then power amplifier efficiency is improved, but EVM of the transmitted signal increases
Solution Approach 1:
A residual signal is introduced as an intermediary component that compensates for the distortion caused by hard clipping. The residual signal is generated by subtracting the hard-clipped signal from the original signal, then processed through least squares filtering and combined with the clipped signal to produce the final output. This intermediary residual signal restores the EVM performance while maintaining the PAR reduction benefits of clipping.
Solution Approach 2:
The patent replaces simple hard clipping with a more sophisticated system that uses least squares filtering and residual signal processing. Instead of directly outputting the hard-clipped signal, the system substitutes a complex processing chain involving matrix operations, filtering, and signal combination to achieve both PAR reduction and EVM preservation.
2Stress or pressure
If hard clipping is applied to reduce PAR, then peak amplitude is reduced, but time-domain properties of the signal deteriorate rapidly
Solution Approach 1:
The patent replaces direct hard clipping with a substituted system using least squares filtering. The residual signal is processed through a least squares filter that minimizes the error between the clipped and original signals while preserving time-domain characteristics. This substitution maintains signal integrity in the time domain while achieving peak amplitude reduction.
Solution Approach 2:
The system uses feedback by continuously comparing the hard-clipped signal with the original signal to generate the residual signal. This residual signal is then processed and fed back into the output signal to correct the distortion. The least squares optimization provides a feedback mechanism that adjusts the residual signal to minimize time-domain deterioration.
3Use of energy by stationary object
If PAR reduction algorithms are applied, then power consumption is reduced, but frequency requirements and RMS EVM requirements may not be met
Solution Approach 1:
The patent substitutes simple clipping with a sophisticated least squares filtering system that processes the residual signal through matrix operations and filtering functions. This substitution ensures that frequency requirements and EVM requirements are met while maintaining power consumption benefits, as the least squares optimization explicitly constrains these parameters.
Solution Approach 2:
The system changes parameters by applying least squares optimization with specific constraints on frequency response and EVM. The filtering function and interpolation function adjust signal parameters to meet system requirements while maintaining the energy efficiency gains from PAR reduction. The matrix function transforms the residual signal to satisfy multiple simultaneous constraints.
Data Source
AI summary
A method of reducing the peak-to-mean ratio of a multi-carrier signal includes the steps of: generating a residual signal from the multicarrier signal, the residual signal representing the difference between the multicarrier signal and a hard-clipped multicarrier signal. The method also includes the steps of applying a least squares function to the residual signal for each carrier of the multi-carrier signal, thereby generating a minimized residual signal for each carrier and combining the minimized residual signals and the multicarrier signal.