Tone Allocation for OFDM Peak Reduction
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Solution Overview
Problem
Current wireless communication systems face challenges in managing peak-to-average power ratio (PAPR) in OFDM signals, leading to inefficient power amplifier operation and potential signal distortion, especially in 5G NR systems that use larger OFDM blocks, resulting in increased PAPR and inefficient resource usage.
Innovation Solution
The implementation of a tone reservation technique where reserved tones within an OFDM symbol are used for PAPR reduction, with the location of these tones selected based on signal-to-noise ratio (SNR) to minimize PAPR, allowing for efficient power amplifier operation and reduced distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If larger OFDM blocks are used in 5G NR systems, then system capacity and data rate are improved, but peak-to-average power ratio (PAPR) increases causing inefficient power amplifier operation and signal distortion
Solution Approach 1:
The patent extracts and separates peak power reduction tones from the regular data tones in the OFDM signal. By dedicating specific tones solely for peak reduction purposes, the system can independently control the amplitude and phase of these tones to cancel out peaks in the time-domain signal, thereby reducing PAPR without compromising the overall system capacity provided by the larger OFDM blocks.
Solution Approach 2:
The patent dynamically adjusts the amplitude and phase parameters of the peak reduction tones based on the instantaneous signal conditions. By changing these parameters adaptively, the system optimizes peak cancellation effectiveness while minimizing the impact on data transmission, thus resolving the contradiction between maintaining high system capacity and reducing harmful PAPR effects.
2Use of energy by moving object
If power amplifiers operate closer to saturation points to improve energy efficiency, then energy efficiency is improved, but signal distortion increases
Solution Approach 1:
The patent applies preliminary anti-action by pre-compensating for potential signal distortion through the peak reduction tones. Before the power amplifier operates near saturation, the reserved tones are configured to preemptively counteract peak excursions that would cause distortion, allowing the amplifier to safely operate closer to saturation while maintaining signal integrity.
Solution Approach 2:
The patent provides beforehand cushioning by introducing peak reduction tones that act as a protective buffer against signal peaks. These tones create a cushioning effect in the time domain, preventing the signal from exceeding the power amplifier's linear operating range, thus enabling efficient operation near saturation without distortion.
3Object-generated harmful factors
If reserved tones are used for PAPR reduction, then PAPR is reduced enabling efficient power amplifier operation, but available tones for data transmission decrease
Solution Approach 1:
The patent applies partial action by using only a subset of tones for peak reduction purposes rather than all tones. By selectively reserving only the necessary number of tones for PAPR control, the system achieves sufficient peak reduction while maximizing the remaining tones available for data transmission, thus balancing both requirements.
Data Source
AI summary
Aspects presented herein may improve the efficiency and performance of the tone reservation PAPR reduction technique by allocating peak reduction tone based at least in part on a channel condition, such as based on the signal to noise ratio of the channel. In some aspects, a transmitting device measures a signal to noise ratio for a plurality of tones within a frequency resource. The transmitting device selects a location of one or more reserved tones (e.g., peak reduction tones) among one or more tones based at least in part on an SNR for one or more tones. The transmitting device transmits data to a receiving device in a subset of the plurality of tones that does not include the one or more peak reduction tones. Other aspects and features are also disclosed.