Constant-Amplitude Biorthogonal Demodulation for Spectral Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing demodulation methods for constant-amplitude multi-code biorthogonal modulation systems face challenges in efficiently demodulating signals and maintaining high performance, particularly due to the wastage of spectrum and non-linearity issues in power amplifiers, which affect Bit Error Rate (BER) and spectral efficiency.
Innovation Solution
A demodulation method utilizing correlators and parity check results to select bit streams with higher correlation values, perform error correction using redundant bits, and optimize orthogonal codes and phases to generate a modulation signal with constant-amplitude characteristics, thereby improving demodulation performance and reducing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-code modulation is used to achieve higher spectral efficiency, then spectral efficiency is improved, but the system requires expensive power amplifiers with wide linearity regions to handle multi-level signals
Solution Approach 1:
The patent changes the amplitude parameter of the modulation signal from variable (multi-level) to constant (biorthogonal). By using biorthogonal modulation where signals have constant amplitude but varying phase and code combinations, the system achieves multi-code spectral efficiency without requiring power amplifiers to handle multi-level amplitude variations, thus resolving the linearity requirement conflict.
2Device complexity
If the linearity region of the power amplifier cannot cover the output levels of a multi-level signal, then device complexity is reduced, but the power amplifier introduces non-linearity that deteriorates system performance
Solution Approach 1:
The patent transforms the signal parameter from multi-level amplitude variation to constant amplitude with phase/code variation. This parameter change ensures that power amplifiers with narrow linearity regions can operate in their linear region without introducing distortion, thereby maintaining system performance while using simpler, less expensive amplifiers.
3Device complexity
If conventional demodulation methods are used for constant-amplitude multi-code biorthogonal signals, then device complexity is kept simple, but demodulation performance and reception quality are insufficient
Solution Approach 1:
The patent segments the demodulation process into distinct stages: correlation detection of biorthogonal signals, parity bit extraction, and systematic error correction. By dividing the demodulation task into these manageable segments with specific functions, the system achieves high demodulation performance through structured processing while keeping individual processing blocks relatively simple.
Solution Approach 2:
The patent performs preliminary correlation detection and parity bit extraction before final error correction. By preparing the signal in advance through correlation with orthogonal codes and extracting parity information early in the process, the system simplifies the final decision-making step and improves overall demodulation reliability through staged processing.
Data Source
AI summary
Disclosed is a demodulation method for enhancing decoding performance of information bits in a constant-amplitude multi-code biorthogonal modulation communication system, which performs encoding to cause the level of a transmission symbol to be constant.