OFDM Signal Modulation Using BPSK Phase Rotation for PAPR Control
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Solution Overview
Problem
The high peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems necessitates high power amplifiers with large linear dynamic ranges, increasing costs and reducing efficiency, and results in in-band distortion and out-of-band dispersion when peak values exceed the amplifier's range.
Innovation Solution
A signal modulating method that utilizes binary phase shift keying (BPSK) constellation point mapping, dual carrier modulation (DCM), and duplication (DUP) operations, with phase changes of 90 degrees or minus 90 degrees applied to specific groups of subcarriers, enabling both I and Q channels for enhanced diversity gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high power amplifier is used to handle large peak signal in OFDM system, then the linear dynamic range is sufficient, but the cost increases and efficiency decreases
Solution Approach 1:
The patent applies parameter changes by modifying the signal characteristics through phase rotation operations on specific subcarriers. By rotating phases of subcarriers at odd positions by 90 degrees or -90 degrees, the peak-to-average power ratio is reduced without changing the information content, thereby allowing the use of lower power amplifiers while maintaining linear dynamic range requirements.
2Reliability
If high power amplifier is used to handle large peak signal in OFDM system, then the linear dynamic range is sufficient, but the cost increases
Solution Approach 1:
The patent reduces the peak-to-average power ratio through parameter changes in the signal modulation process. By applying phase rotation to specific subcarriers, the signal peaks are reduced, which allows the system to use cost-effective amplifiers with lower power requirements while still meeting the linear dynamic range specifications.
3Power
If peak value exceeds the linear dynamic range of high power amplifier, then the amplification is sufficient, but in-band distortion and out-of-band dispersion are caused
Solution Approach 1:
The patent changes the signal parameters by applying phase rotation operations to reduce the peak-to-average power ratio before amplification. This ensures that the signal peaks remain within the linear dynamic range of the amplifier, preventing in-band distortion and out-of-band dispersion while maintaining sufficient signal amplification.
Solution Approach 2:
The patent performs preliminary phase rotation operations on the subcarriers before the signal enters the power amplifier. This preliminary action reduces the peak values in advance, ensuring that the subsequent amplification process operates within the linear dynamic range and avoids generating distortion and dispersion.
4Reliability
If phase change is applied to first data in first group of subcarriers, then diversity gain is enhanced, but the complexity of modulation increases
Solution Approach 1:
The patent applies local quality by selectively applying phase rotation only to specific subcarriers (those at odd positions) rather than all subcarriers. This localized approach enhances diversity gain for the affected subcarriers while minimizing the overall complexity increase, as only a portion of the modulation process requires additional phase rotation operations.
Data Source
AI summary
The technology of this disclosure relates to a signal modulating method, a signal demodulating method, a device, a storage medium, and a program product. In the signal modulating method according to a first aspect of this disclosure, a sending device modulates a bit sequence onto a plurality of subcarriers through binary phase shift keying (BPSK) constellation point mapping, dual carrier modulation (DCM), and a duplication (DUP) operation, where the plurality of subcarriers include a first group of subcarriers and a second group of subcarriers. Then, the sending device changes a phase of first data carried in the first group of subcarriers by 90 degrees or minus 90 degrees, and further generates a modulation signal based on the first data that is carried in the first group of subcarriers and whose phase has been changed and second data carried in the second group of subcarriers.