Signal Distortion Mitigation via Precoding
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Solution Overview
Problem
Existing communication systems face challenges in mitigating signal distortions at receivers due to peak-to-average power ratio (PAPR) reduction, especially in scenarios without detailed knowledge of the channel between transmitters and receivers, which limits the achievable signal-to-interference-and-noise ratio (SINR) and degrades power amplifier efficiency.
Innovation Solution
The method involves precoding signal distortions to spread them spatially, reducing their alignment with intended signals, thereby mitigating their impact at receivers without requiring detailed channel knowledge. This is achieved by determining distortion signals, precoding them using orthogonal precoders, and combining them constructively in directions other than those of the desired signals, allowing for PAPR reduction and spectrum shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If PAPR reduction techniques (clipping and filtering, pulse/peak cancellation) are applied to improve power amplifier efficiency, then power amplifier efficiency is improved, but signal distortion increases
Solution Approach 1:
The patent introduces an intermediary signal processing stage between the PAPR reduction block and the transmitter that processes the distorted signal to mitigate its harmful effects. The intermediary computes a distortion compensation signal based on the difference between the original and PAPR-reduced signals, then adds this compensation to the transmitted signal, thereby reducing the net distortion at the receiver while maintaining power amplifier efficiency.
Solution Approach 2:
The patent implements a feedback mechanism where the transmitter processes the distorted signal through an intermediary that calculates distortion compensation based on the actual distorted output. This feedback loop allows the system to measure the distortion introduced by PAPR reduction and actively compensate for it, resolving the contradiction between maintaining high power amplifier efficiency and minimizing signal distortion.
2Use of energy by moving object
If PAPR is reduced to improve power amplifier efficiency, then power amplifier efficiency is improved, but achievable SINR at receivers is limited
Solution Approach 1:
The intermediary signal processing stage acts as a mediator that preserves the benefits of PAPR reduction for power amplifier efficiency while actively working to maintain high SINR at receivers. By computing distortion compensation signals and adding them back to the transmitted signal, the intermediary ensures that the signal quality required for high SINR is maintained even with aggressive PAPR reduction applied.
3Object-generated harmful factors
If distortion compensation is applied to mitigate signal distortion, then signal distortion is reduced, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by computing and applying distortion compensation at the transmitter before signal transmission. The intermediary calculates the distortion compensation signal in advance based on the PAPR-reduced signal characteristics, then adds this compensation to the transmitted signal. This preliminary compensation approach reduces the need for complex receiver-side processing and overall system complexity while effectively mitigating signal distortion.
4Use of energy by moving object
If more aggressive PAPR reduction is applied to further improve power amplifier efficiency, then power amplifier efficiency is improved, but level of distortions increases
Solution Approach 1:
The feedback mechanism in the intermediary continuously monitors the distortion level resulting from aggressive PAPR reduction and dynamically adjusts the distortion compensation signal. This allows the system to apply aggressive PAPR reduction for high power amplifier efficiency while the feedback loop ensures that distortion levels are actively controlled and mitigated, preventing them from becoming excessive.
Solution Approach 2:
The intermediary serves as a mediator that enables the system to push PAPR reduction to more aggressive levels for improved power amplifier efficiency while simultaneously providing distortion mitigation. By processing the distorted signal through the intermediary and adding appropriate compensation, the system can achieve higher power amplifier efficiency without being constrained by excessive distortion levels.
Data Source
AI summary
A method for signal distortion mitigation in a communication device with at least one transmitter in a communication system, generating a signal for transmission for each of the at least one transmitter; performing Peak-to-Average Power Ratio (PAPR) reduction and spectrum shaping of each of the generated signal to provide a distorted signal for transmission; determining signal distortions of the distorted signals, and precoding the determined signal distortions. The method further generating a composite signal for transmission based on the precoded determined signal distortions and the generated signal for transmission, to provide a composite signal, and transmitting the composite signal to at least one receiving communication device, wherein the precoding enables mitigating the signal distortion impact on the at least one receiver.