Symmetrical Phase-Shift Keying Modulation Bandwidth Optimization
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Solution Overview
Problem
Existing phase-shift keying (PSK) methods, such as BPSK and QPSK, require wider bandwidth due to sharp phase changes, leading to inefficient use of limited spectrum resources and potential communication quality degradation from interference with other signals.
Innovation Solution
The implementation of symmetrical phase-shift keying (SPSK) with a constellation diagram that divides the 2π phase space into 2n+1 directions, where 2n directions are default and the remaining 2n are complementary, allowing phase differences of π between corresponding directions, reducing the maximum phase change between symbols to π/2 and enabling more efficient bandwidth utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PSK methods (BPSK, QPSK) are used, then data transmission is achieved, but bandwidth efficiency deteriorates due to sharp phase changes requiring wider bandwidth
Solution Approach 1:
The patent applies asymmetry by introducing a reference phase that breaks the symmetry of conventional PSK constellations. Instead of treating all phase transitions equally, the method distinguishes between transitions relative to a reference phase and transitions relative to other phases, enabling more controlled phase changes that reduce bandwidth requirements while maintaining transmission reliability
Solution Approach 2:
The patent changes the phase parameter representation by using a reference phase as a baseline. The phase of each symbol is expressed relative to this reference, allowing the system to control and limit phase transitions to maximum π/2 rather than π, thereby reducing the spectral width and improving bandwidth efficiency
2Productivity
If larger phase differences between symbols are used, then more information can be transmitted per symbol, but pulse sharpness increases requiring broader spectrum
Solution Approach 1:
The patent transforms the phase parameter space by introducing a reference phase and expressing all symbol phases relative to it. This parameter transformation allows the system to achieve the same information transmission rate while limiting the actual phase transitions to π/2, thereby reducing spectral bandwidth requirements without sacrificing productivity
Data Source
AI summary
Methods and apparatuses employing symmetrical phase-shift keying (SPSK) for data modulation and demodulation. Each symbol in a transmission signal carries n-bit information and is transmitted with one of 2n+1 directions. Half directions among the 2n+1 directions are regarded as default directions and the remaining are regarded as complementary directions. Each default direction has a corresponding complementary direction with a phase difference of π and representing the same n-bit information as the default direction. The phase difference between any two successive symbols after modulation is less than or equal to π/2.