OFDM Sequence Design for CM and PAPR Reduction
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Solution Overview
Problem
In wireless communication systems, the high cubic metric (CM) and peak-to-average ratio (PAPR) of OFDM signals lead to signal distortion and increased error vector magnitude (EVM), which degrade demodulation performance, necessitating reduced transmit power and compromising link quality.
Innovation Solution
A signal transmission method where data and reference signals are carried on odd and even elements of a sequence, respectively, and mapped to subcarriers in a specific design to reduce CM/PAPR, improving link quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data and reference signals are transmitted using conventional OFDM methods, then the transmission capability is maintained, but the cubic metric and peak-to-average ratio increase causing signal distortion and increased EVM
Solution Approach 1:
The patent segments the sequence elements into different types (first sequence elements for data, second sequence elements for reference signals) and maps them to different subcarrier groups. This segmentation allows independent optimization of each group's properties, enabling the data-carrying elements to be designed with lower CM/PAPR characteristics while maintaining reference signal functionality separately.
Solution Approach 2:
The patent applies different mapping strategies to different parts of the frequency spectrum. Specifically, first sequence elements are mapped to a first group of subcarriers while second sequence elements are mapped to a second group of subcarriers. This local differentiation allows the system to optimize specific regions for low CM/PAPR performance while maintaining overall transmission capability.
2Object-generated harmful factors
If transmit power is reduced to lower EVM, then signal distortion decreases, but demodulation performance at the receive end deteriorates
Solution Approach 1:
The patent changes the structural parameters of the transmitted sequence by using specific mathematical formulations for generating the sequence elements. The first sequence elements are generated using one formula while second sequence elements use another formula, creating a structured sequence with controlled amplitude and phase characteristics that inherently produce lower CM/PAPR, allowing transmission at optimal power levels without excessive EVM.
3Power
If a high peak-to-average ratio is used to reduce transmit power requirements, then power amplifier linearity improves, but demodulation performance decreases
Solution Approach 1:
The patent introduces dynamic characteristics into the sequence design by using time-varying phase rotations and position-dependent mappings. The sequence elements incorporate dynamic phase terms that adapt to the specific element position and type, creating a more flexible signal structure that maintains power efficiency while improving demodulation robustness through controlled variations in the time-frequency domain.
Data Source
AI summary
This application relates to the field of wireless communications technologies, and in particular, to a data processing method, apparatus, and system. This application provides a data processing method. A transmit device uses a sequence to carry data and a reference signal. The transmit device carries the two channels of data on an odd element and an even element of the sequence, respectively. The transmit device successively maps the sequence that carries the two channels of data to allocated subcarriers, and then sends the data in an orthogonal frequency division multiplexing (OFDM) manner. This application is intended to decrease cubic metric (CM)/peak-to-average ratio of a transmitted signal of an orthogonal frequency division multiplexing OFDM system through sequence design and mapping of the two channels of data to subcarriers, thereby improving link quality of an entire transmission system.