OFDM Carrier Mapping for PAPR Reduction
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Solution Overview
Problem
The existing OFDM communication systems face challenges in reducing Peak-to-Average Power Ratio (PAPR), which leads to increased manufacturing costs due to the need for expensive power amplifiers and potential signal distortion, especially in mobile terminals.
Innovation Solution
The method involves mapping input bit streams into transfer symbols and modifying the amplitudes and phases of specific sub-carrier groups using constellation modification information, allowing for the transmission of additional data without additional control information, thereby generating a new channel for data communication and reducing PAPR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OFDM transmission is used, then data communication is achieved, but PAPR increases leading to expensive power amplifiers and signal distortion
Solution Approach 1:
The patent segments the data transmission by creating multiple virtual carriers through DFT spreading, where each virtual carrier is assigned to specific physical subcarriers. This segmentation allows the signal to be distributed across multiple lower-power carriers, reducing the peak power requirement while maintaining data integrity and communication reliability.
2Reliability
If additional control information is transmitted to enable PAPR reduction, then signal quality improves, but transmission efficiency decreases
Solution Approach 1:
The patent merges the data transmission and PAPR control functions into a single process. The DFT spreading operation simultaneously achieves both objectives: it redistributes the signal energy to reduce PAPR while the resulting spread spectrum signal inherently provides the necessary control information for signal reconstruction, eliminating the need for separate control channels.
3Reliability
If expensive power amplifiers are used to handle high PAPR, then signal distortion is reduced, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive, high-linearity power amplifiers with cheaper, lower-linearity amplifiers by preprocessing the signal through DFT spreading. This technique reduces the PAPR requirement, allowing the use of cost-effective power amplifiers that would otherwise be unsuitable, thereby significantly reducing manufacturing costs while maintaining signal fidelity.
4Speed
If mobile terminals use high PAPR transmission, then communication range is extended, but terminal cost and power consumption increase
Solution Approach 1:
The patent changes the signal parameters by applying DFT spreading, which transforms the signal spectrum and reduces PAPR. This parameter transformation allows mobile terminals to achieve extended communication range through more efficient power utilization, reducing the peak power demands while maintaining or extending the effective communication distance, thereby lowering overall power consumption.
Data Source
AI summary
An apparatus for receiving signals includes a receiver for receiving a time domain signal from a transmitter, wherein at least one first information bit is mapped, resulting in at least one first mapped symbol; at least one second information bit is mapped, resulting in at least one second mapped symbol; the at least one second mapped symbol is multiplied by at least one third information bit; and the time domain signal is generated from the at least one first mapped symbol and the at least one second mapped symbol.