Orthogonal BPSK Modulation for Low PAPR Wireless Systems
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Solution Overview
Problem
Wireless communication systems face challenges in efficiently managing power consumption and peak-to-average power ratio (PAPR) for devices with limited power supply and infrequent data transmission, such as machine-type communication devices, which require tailored communication techniques that prioritize power conservation over spectral efficiency.
Innovation Solution
The implementation of orthogonal binary phase shift keying (BPSK) modulation techniques, where binary sequences are modulated on orthogonal axes of a complex plane, and optionally smoothed using a finite impulse response (FIR) filter, to reduce PAPR and improve power amplifier efficiency, while also applying an offset quadrature phase shift keying (OQPSK) modulation with cyclic prefix insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional modulation schemes are used, then spectral efficiency is maintained, but peak-to-average power ratio increases and power amplifier efficiency deteriorates
Solution Approach 1:
The binary sequence is divided into two separate binary sequences, with each sequence modulated on a different orthogonal axis (I-axis and Q-axis) using BPSK. This segmentation allows independent control of phase transitions on each axis, reducing peak power occurrences while maintaining spectral efficiency through the orthogonal structure.
2Use of energy by moving object
If filtering is applied to reduce PAPR, then power amplifier efficiency improves, but device complexity increases
Solution Approach 1:
The invention changes the modulation parameters by using orthogonal BPSK modulation on separated axes, which inherently reduces PAPR. This parameter change eliminates the need for complex filtering operations, as the orthogonal structure naturally limits peak power occurrences while maintaining signal integrity.
3Use of energy by moving object
If orthogonal BPSK modulation is applied, then peak-to-average power ratio is reduced, but modulation complexity increases
Solution Approach 1:
The binary sequence is divided into two separate binary sequences, with each sequence modulated on a different orthogonal axis (I-axis and Q-axis) using BPSK. This segmentation allows independent control of phase transitions on each axis, reducing peak power occurrences while maintaining spectral efficiency through the orthogonal structure.
Solution Approach 2:
The invention transitions from single-axis modulation to two-dimensional orthogonal modulation, where the first binary sequence modulates the in-phase component and the second binary sequence modulates the quadrature component. This dimensional expansion reduces PAPR by distributing power across orthogonal dimensions while maintaining overall data rate.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A transmitting device may modulate a first binary sequence using binary phase shift keying on a first axis of a complex plane. The device may modulate a second binary sequence using binary phase shift keying on a second plane of a complex axis. The first axis and the second axis may be orthogonal. The device may transmit the first binary sequence and the second binary sequence according to the modulation of the first binary sequence and the second binary sequence.