OFDM Subcarrier Allocation for PAPR Reduction in PPDU Transmission
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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 sending a physical protocol data unit (PPDU) with resource unit allocation information that separates subcarrier sets, using one set for data and another for a sequence to reduce PAPR, and optionally using null, guard, or pilot subcarriers, or applying an adjustment factor to data subcarriers to lower PAPR without affecting data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM system uses multiple subcarriers for data transmission, then transmission capacity is improved, but PAPR increases causing power amplifier efficiency degradation
Solution Approach 1:
The patent divides the available subcarriers into two distinct sets: a first subcarrier set dedicated for data transmission and a second subcarrier set dedicated for PAPR reduction sequences. This segmentation allows independent optimization of data capacity and PAPR control without interference, resolving the contradiction between transmission capacity and power amplifier efficiency.
Solution Approach 2:
The patent extracts specific subcarriers (the second subcarrier set) from the overall subcarrier pool and assigns them a specialized function for PAPR reduction. By taking out these specific resources and dedicating them to PAPR control, the system maintains high transmission capacity on the remaining subcarriers while achieving effective PAPR reduction.
2Loss of energy
If PAPR is reduced by adjusting subcarrier values, then power amplifier efficiency is improved, but data transmission performance may be affected
Solution Approach 1:
The patent segments the subcarrier resources into functionally independent sets: first subcarriers for data and second subcarriers for PAPR reduction. This segmentation ensures that PAPR adjustment operations on the second subcarrier set do not interfere with data transmission on the first subcarrier set, maintaining both power amplifier efficiency and data transmission reliability.
Solution Approach 2:
The patent introduces a second subcarrier set as an intermediary element that mediates between the conflicting requirements of high transmission capacity and low PAPR. These intermediary subcarriers carry specialized sequences designed for PAPR reduction, allowing the system to achieve power amplifier efficiency improvement without compromising data transmission performance on the primary data subcarriers.
3Loss of energy
If resource units are allocated for PAPR reduction sequences, then PAPR is reduced, but available resources for data transmission decrease
Solution Approach 1:
The patent changes the parameter allocation of subcarrier resources by designating specific subsets (second subcarrier set) for PAPR reduction functions. By modifying the functional parameters of these resource units and assigning them to PAPR control, the system achieves effective PAPR reduction while the first subcarrier set maintains full capacity for data transmission, optimizing the overall resource utilization.
Data Source
Figure 1~2B
Figure 3
Figure 4A
AI summary
This application provides an information transmission method, and an apparatus, to reduce a PAPR. In the method, a first apparatus sends a 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.