Demodulation Method Using Discrete State Index for Modulation Ambiguity
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Solution Overview
Problem
Existing demodulation methods for devices with modulation index range, such as Bluetooth, suffer from low performance due to ambiguity in modulation index, leading to errors in signal demodulation.
Innovation Solution
A demodulation method that uses a rational number within the modulation index range as a first modulation index to determine states, and a second modulation index to obtain practical accumulated phases, allowing for error correction and improved accuracy through branch metric calculation and survivor path determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If differential demodulation or matched filter bank demodulation is used to handle modulation index ambiguity, then demodulation can be performed, but demodulation performance is low
Solution Approach 1:
The patent changes the parameter representation by introducing a discrete state index instead of continuously tracking the ambiguous modulation index. The accumulated phase is quantized into discrete states, transforming the continuous parameter estimation problem into a discrete state tracking problem that can be solved using Viterbi algorithm for optimal path selection.
Solution Approach 2:
The patent introduces an intermediary accumulated phase parameter that bridges the received signal and the transmitted information bits. By tracking the accumulated phase through discrete states and using it as an intermediary to compute branch metrics, the system can resolve modulation index ambiguity without directly estimating the modulation index itself.
2Device complexity
If a fixed modulation index is assumed for demodulation, then the number of states can be controlled, but errors occur due to modulation index ambiguity
Solution Approach 1:
The patent makes the system dynamic by allowing the effective modulation index to vary within a range while maintaining a fixed nominal value for state definition. The actual accumulated phase computation uses a practical modulation index that can differ from the fixed value, enabling the system to adapt to modulation index variations without changing the state structure.
Solution Approach 2:
The patent segments the demodulation process into two independent parts: state definition based on a fixed modulation index (controlling complexity) and accumulated phase computation based on a practical modulation index (improving accuracy). This segmentation allows each part to optimize for its specific purpose without compromising the other.
Data Source
AI summary
The present disclosure relates to a demodulation method, apparatus, and device. Some embodiments of the present disclosure are beneficial to improving demodulation performance.