QPSK Modulator Mapping for 16QAM Without Variable Weights
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current communication systems, such as WCDMA, face challenges in generating higher order modulations like 16QAM using existing QPSK modulators, as they require complex configurations with variable weights and Discontinuous Transmission (DTX) bits to form constellation points.
Innovation Solution
A method and system that utilize two QPSK modulators with constant weights and DTX bits to generate higher order modulations by mapping complex binary sequences to constellation points and summing their output signals, eliminating the need for new hardware and enabling flexible implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If QPSK modulators are used to generate higher order modulation (16QAM), then existing hardware can be utilized, but complex weight adjustments and variable DTX are required increasing system complexity
Solution Approach 1:
The patent changes the parameter of DTX bits from variable to constant values. By setting specific DTX bit patterns (e.g., first DTX bit=0, second DTX bit=1 for certain constellation points), the system eliminates the need for complex variable weight adjustments while maintaining the ability to generate all 16QAM constellation points using existing QPSK modulator hardware.
2Adaptability or versatility
If variable DTX bits are used to generate 16QAM constellation points, then all constellation points can be formed, but processing load increases
Solution Approach 1:
The patent transforms the DTX bit parameter from a dynamically variable state to a constant predetermined state for each constellation point. This eliminates the need for real-time variable DTX processing, reducing computational complexity and processing load while maintaining full 16QAM constellation generation capability through systematic mapping.
3Device complexity
If constant weights are used in QPSK modulators, then hardware implementation is simplified, but flexibility in generating different modulation schemes is reduced
Solution Approach 1:
The patent segments the 16QAM constellation generation into multiple QPSK modulator components, each handling specific constellation points with constant weights. By dividing the modulation process into discrete segments (different QPSK modulators for different constellation point groups), the system achieves simplified hardware implementation while maintaining flexibility through combinatorial mapping of segmented outputs.
Solution Approach 2:
The patent merges outputs from multiple QPSK modulators with constant weights to generate the complete 16QAM constellation. By combining the simplified constant-weight modulator outputs through appropriate mapping and summation, the system recovers the full flexibility of higher-order modulation while retaining the hardware simplicity of constant-weight implementation.
Data Source
AI summary
A method and system generates a higher order modulation, in which a complex sequence of binary digits corresponding to symbols of a higher order modulation is received. The symbols correspond to constellation points of the higher order modulation. First mapping means map the symbols of the higher order modulation to first constellation points of a first QPSK modulation and output an output signal of the first QPSK modulation corresponding to the first constellation points. Similarly, second mapping means map the symbols of the higher order modulation to second constellation points of a second QPSK modulation and output an output signal of the second QPSK modulation corresponding to the second constellation points. Adding means add the output signals of the first and second QPSK modulations, thereby generating the constellation points of the higher order modulation.