Peak Reduction Tone Allocation for 5G Power Amplifier Efficiency
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Solution Overview
Problem
Power amplifiers in wireless communication systems, particularly those used in 5G NR, face inefficiency due to high peak-to-average-power ratio (PAPR) of OFDM signals, leading to non-linearity and distortion, which is exacerbated by the need for significant gain backoff to avoid saturation.
Innovation Solution
A peak reduction tone selection system that efficiently identifies a sequence of peak reduction tones using a cost function calculation, allowing for reduced PAPR by transforming the kernel to resemble a delta function, thereby minimizing sidelobes and enabling effective PAPR reduction without compromising data rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gain backoff is increased to avoid saturation in power amplifiers, then non-linearity and distortion are reduced, but transmitter efficiency deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal peak reduction tone sequences in lookup tables before transmission. The processor selects pre-computed tone sequences that will reduce PAPR without requiring real-time complex calculations, enabling efficient operation closer to saturation while maintaining signal quality.
Solution Approach 2:
The patent changes parameters by modifying specific tone sequences to reduce PAPR while preserving data integrity. By adjusting the peak reduction tones and using techniques like selective tone nulling and phase rotation, the system transforms the signal parameters to achieve lower PAPR, allowing reduced gain backoff and improved transmitter efficiency.
2Productivity
If OFDM resource block size is increased to achieve higher data rates, then productivity is improved, but PAPR increases rapidly
Solution Approach 1:
The patent segments the OFDM signal into multiple tone sequences, separating peak reduction tones from data-carrying tones. By dividing the frequency spectrum into distinct segments with specific functions (some tones for peak reduction, others for data), the system can manage PAPR independently while maintaining high data rates through efficient resource block utilization.
Solution Approach 2:
The patent introduces peak reduction tones as intermediary elements that mediate between the high PAPR problem and the data transmission requirement. These special tones act as a buffer or mediator that absorbs peak fluctuations, allowing the main data tones to carry information at high rates without being constrained by PAPR limitations.
3Loss of energy
If peak reduction tones are added to reduce PAPR, then transmitter efficiency is improved, but device complexity increases
Solution Approach 1:
The patent significantly reduces processing complexity by performing all complex peak reduction tone calculations in advance and storing results in lookup tables. During actual transmission, the processor only needs to perform simple table lookups and selections, avoiding real-time complex computations while still achieving PAPR reduction and improved transmitter efficiency.
Data Source
AI summary
A user equipment for wireless communications includes a memory configured to store a peak reduction tone (PRT) table and a processor configured to retrieve a plurality of PRT sequences from the PRT table. The plurality of PRT sequences includes a first PRT sequence based upon a first data rate and a second PRT sequence based upon a second data rate. The second data rate is larger than the first data rate, and the second PRT sequence is a subset of the first PRT sequence. The user equipment also includes a power amplifier operable to transmit data with the first PRT sequence according to the first data rate or with the second PRT sequence according to the second data rate.