Human Body Communication Interference Rejection via DDR Sampling
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Solution Overview
Problem
Human Body Communication (HBC) systems face interference issues due to the human body acting as an antenna at specific frequency bands, particularly in the FM range, leading to energy-inefficient implementations and security concerns, as existing methods like adaptive frequency hopping and fixed narrowband signaling fail to effectively suppress interference.
Innovation Solution
An adaptive broadband non-return-to-zero (NRZ) signaling scheme using a dual data rate (DDR) receiver with resettable integration, which integrates and samples signals to suppress interference, effectively canceling out FM interference and enhancing signal-to-interference ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adaptive frequency hopping or fixed narrowband signaling is used to avoid FM interference, then interference rejection is improved, but energy efficiency deteriorates and device complexity increases due to bulky filters
Solution Approach 1:
The patent changes the signaling scheme from narrowband to broadband non-return-to-zero (NRZ) signaling, fundamentally altering the frequency domain characteristics. This parameter change allows the system to occupy a wider bandwidth while maintaining interference rejection through the specific properties of NRZ signaling and dual-data-rate detection, eliminating the need for bulky narrowband filters and reducing energy consumption.
Solution Approach 2:
The patent employs dual-data-rate signaling where data is transmitted at twice the symbol rate, dynamically utilizing both even and odd samples. This dynamic approach allows the system to process interference differently across different time samples, achieving interference rejection without requiring energy-intensive adaptive frequency hopping or bulky filtering hardware.
2Object-affected harmful factors
If narrowband signaling is used to avoid FM interference, then interference rejection is improved, but device complexity increases due to bulky filters
Solution Approach 1:
The patent transitions from narrowband signaling to broadband NRZ signaling, fundamentally changing the frequency domain parameters. This eliminates the need for complex narrowband filters while maintaining interference rejection through the inherent properties of NRZ signaling combined with dual-data-rate detection that processes even and odd samples differently.
Solution Approach 2:
The patent extracts and utilizes only the necessary processing steps (dual-data-rate detection with different even/odd sample processing) while eliminating unnecessary components (bulky narrowband filters). By taking out the essential interference rejection mechanism and removing the complex filtering hardware, the system achieves simpler device complexity while maintaining interference rejection capability.
3Use of energy by moving object
If the human body is used as a conducting medium for HBC, then energy efficiency is improved, but interference susceptibility increases due to the body acting as an antenna at FM frequencies
Solution Approach 1:
The patent changes the signaling parameters from narrowband to broadband NRZ signaling, which fundamentally alters how the signal interacts with the body's resonant frequencies. This parameter change, combined with dual-data-rate detection, allows the system to maintain ultra-low power operation through the body as a conducting medium while achieving interference rejection by processing even and odd samples differently to cancel out FM band interference.
Data Source
AI summary
A communication interference rejection system, comprising a dual data rate (DDR) receiver operatively connected to a device connected to a body of a user. The DDR receiver is configured to receive a signal transmitted through the body of the user, with the signal comprising a relatively substantially small constant amplitude component and a relatively large sinusoidal or modulated interference component, said interference component due to human body antenna effect. The receiver integrates the signal and sample at a sampling time, with the sampling time defined as Ts=n/Finterference, wherein Finterference is the frequency of the modulated interference component and n is an integer.