FMCW Slope Scrambling to Reduce Multi-Node RF Interference
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Solution Overview
Problem
FMCW-based RF sensing in wireless networks is vulnerable to interference due to the simplicity of its waveform, which hinders accurate scaling and implementation in environments with multiple sensing nodes.
Innovation Solution
Implement slope scrambling by randomizing the FMCW transmission sequence with a scrambling ID based on cell, UE ID, frame number, or symbol index, and using triangular waveforms to avoid frequency jumps, enabling efficient RF sensing across multiple devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FMCW waveform is used for RF sensing, then sensing function can be performed, but interference from multiple sensing nodes increases
Solution Approach 1:
The patent applies parameter changes by randomizing the FMCW transmission sequence through slope scrambling. Different sensing nodes are assigned different scrambling IDs (based on cell ID, UE ID, frame number, or symbol index) that modulate the chirp slope parameters. This transforms the simple FMCW waveform into a scrambled version with unique spectral characteristics for each node, allowing differentiation between multiple sensing nodes and reducing interference while maintaining sensing functionality.
2Device complexity
If simple FMCW waveform is used, then device complexity is reduced, but interference vulnerability increases
Solution Approach 1:
The patent implements dynamics by making the FMCW transmission sequence time-varying through slope scrambling. Instead of using a static simple chirp waveform, the system dynamically randomizes the slope parameters based on scrambling IDs that change over time (frame number, symbol index). This dynamic transformation maintains the basic FMCW structure for low complexity while introducing variability that prevents interference from multiple nodes, effectively resolving the contradiction between simplicity and interference resistance.
Data Source
AI summary
Frequency-modulated continuous wave (FMCW) slope scrambling for radio frequency (RF) sensing may be performed by a sensing node. The sensing node can receive a slope configuration from a configuring node of a wireless network, wherein the slope configuration includes one or more parameters indicative of a frequency slope value for each chirp of an FMCW transmission sequence to be used by the sensing node for RF sensing. The sensing node can further perform an RF sensing function in accordance with the slope configuration.