PPDU Subcarrier Set Allocation for OFDM PAPR Reduction
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Solution Overview
Problem
The high peak to average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems affects system performance by reducing the efficiency of power amplifiers and signal-to-quantization-noise ratios, particularly in high-frequency scenarios.
Innovation Solution
The method involves allocating non-overlapping first and second subcarrier sets within a physical protocol data unit (PPDU) and using a sequence on the second set to reduce PAPR, with optional use of null, guard, and pilot subcarriers, and adjusting subcarrier values through guard intervals or coefficients to minimize PAPR without affecting data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM modulation is used to achieve high data transmission rates, then transmission capacity is improved, but PAPR increases causing power amplifier efficiency to deteriorate
Solution Approach 1:
The patent divides the frequency spectrum into multiple non-overlapping subcarrier sets (first subcarrier set for data, second subcarrier set for PAPR reduction sequences). This segmentation allows independent optimization of each subcarrier set, enabling PAPR reduction without compromising the data transmission capacity of the first subcarrier set.
Solution Approach 2:
The patent extracts the PAPR reduction function from the data transmission function by allocating a separate second subcarrier set dedicated to carrying PAPR reduction sequences. This extraction allows the PAPR reduction mechanism to operate independently while the first subcarrier set maintains optimal data transmission performance.
2Loss of energy
If PAPR is reduced by adjusting subcarrier values, then power amplifier efficiency is improved, but transmission performance may deteriorate
Solution Approach 1:
The patent segments the subcarriers into two distinct groups: the first subcarrier set that carries data and maintains transmission performance, and the second subcarrier set that carries PAPR reduction sequences. This segmentation ensures that adjustments to the second subcarrier set do not affect the integrity of data transmitted on the first subcarrier set.
Solution Approach 2:
The second subcarrier set acts as an intermediary mechanism for PAPR reduction. By carrying specifically designed PAPR reduction sequences, it mediates the conflict between maintaining high peak values (which improve power amplifier efficiency) and avoiding excessive PAPR (which protects transmission performance).
3Loss of energy
If subcarrier values are dynamically adjusted to reduce PAPR, then PAPR is reduced, but system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-designing and pre-allocation of the second subcarrier set for PAPR reduction sequences before data transmission begins. The resource unit allocation information预先 indicates the configuration of both subcarrier sets, allowing the receiver to prepare appropriate processing algorithms in advance, thereby reducing real-time computational complexity.
Solution Approach 2:
The patent introduces dynamics by allowing flexible configuration of the second subcarrier set parameters (such as null subcarriers, guard subcarriers, and pilot subcarriers) based on different transmission scenarios. This dynamic adaptability enables the system to optimize PAPR reduction effectiveness while managing complexity through scenario-specific configurations.
4Ease of operation
If resource unit allocation information is transmitted to indicate subcarrier sets, then receiver complexity is reduced, but overhead increases
Solution Approach 1:
The resource unit allocation information serves multiple functions simultaneously: it indicates the allocation of resource units to users, specifies the configuration of the first and second subcarrier sets, and provides the receiver with all necessary information for both data reception and PAPR reduction sequence processing. This multi-functionality reduces the need for separate signaling messages.
Solution Approach 2:
The patent utilizes parameter changes by encoding the subcarrier set configurations within the existing resource unit allocation information structure. By modifying parameters such as resource unit indices and allocation patterns, the system conveys additional information about the second subcarrier set without requiring a completely new signaling format, thereby managing overhead efficiently.
Data Source
AI summary
This application provides an information transmission method, and an apparatus, to reduce a peak to average power ratio (PAPR). In the method, a first apparatus sends a physical protocol data unit (PPDU) to a second apparatus. The PPDU includes resource unit allocation information, and the resource unit allocation information indicates one or more resource units. The resource unit allocation information further indicates that the one or more resource units include a first subcarrier set and a second subcarrier set, and the first subcarrier set and the second subcarrier set do not overlap. The PPDU includes first data sent on the first subcarrier set and a sequence sent on the second subcarrier set, and the sequence is used to reduce the PAPR. Based on the foregoing solution, the PAPR may be flexibly reduced by changing a value of each second subcarrier included in the second subcarrier set.