Constant-Amplitude Modulation Using Weighted Gaussian Pulses
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Solution Overview
Problem
Current telecommunications systems using constant-amplitude modulations face complexity and performance degradation when increasing the number of states beyond two, particularly due to inter-symbol interference and increased modulation speed, which complicates receiver design and leads to significant noise interference.
Innovation Solution
A method and system for constant-amplitude and continuous-phase modulation that involves associating each symbol with a frequency pulse of adjustable length and phase variation, using a combination of weighted Gaussian pulses to minimize inter-symbol interference, and employing a single impulse response filter for demodulation, regardless of the number of states, to optimize signal transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of states in constant-amplitude modulation is increased beyond two to increase bit rate, then the useful bit rate is improved, but the receiver complexity and inter-symbol interference increase significantly
Solution Approach 1:
The frequency pulse associated with each symbol is segmented into a sum of L weighted Gaussian pulses, where L is an integer greater than or equal to 1. This segmentation allows the pulse to be constructed from simpler components that can be efficiently processed, reducing the computational burden on the receiver while maintaining the ability to convey multiple bits per symbol.
Solution Approach 2:
The invention changes the parameters of the frequency pulse by expressing it as a combination of Gaussian pulses with adjustable weights and time shifts. By optimizing these parameters, the system achieves reduced inter-symbol interference and simplified receiver design while maintaining high bit rates through multi-state modulation.
2Productivity
If the modulation speed is increased to convey more bits per symbol, then the useful bit rate is improved, but the inter-symbol interference and noise interference increase
Solution Approach 1:
The frequency pulse parameters are optimized by expressing the pulse as a sum of Gaussian functions with specific weights and time shifts. This parameterization allows for reduced inter-symbol interference while maintaining high modulation speeds, as the Gaussian components can be carefully tuned to minimize overlap between adjacent symbols.
3Measurement precision
If a complex receiver design is used to handle multi-state modulation, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The receiver design is simplified by segmenting the frequency pulse into Gaussian components, which allows for a more straightforward detection process. Instead of handling a complex multi-state modulation directly, the receiver can process the simpler Gaussian components, reducing overall receiver complexity while maintaining detection accuracy.
Data Source
AI summary
A constant-amplitude and continuous-phase modulation method for modulating digital data and for demodulating said modulated signal, said data taking the form of symbols a(n) that can take a number M of states at least equal to 2, the method including, in transmission, use of a voltage-controlled oscillator (VCO) for which the control is the sum of pulses he(a(n), t−n T), the form and the amplitude of which depends on the value of a(n); and, in reception, use of a single impulse response filter C0(t) regardless of the value of M in transmission, said functions he and C0 having a number of parameters that are optimized in the design of the system in order to obtain at the output of the filter C0 a constellation that is as close as possible to the theoretical constellation.