ADR-002: Signal Processing Library Selection

Status

Accepted

Context

CSI signal processing requires FFT operations, complex number handling, and matrix operations. We need to select appropriate Rust libraries that provide Python/NumPy equivalent functionality.

Decision

We will use the following libraries:

Library	Purpose	Python Equivalent
ndarray	N-dimensional arrays	NumPy
rustfft	FFT operations	numpy.fft
num-complex	Complex numbers	complex
num-traits	Numeric traits	-

Key Implementations

1. Phase Sanitization: Multiple unwrapping methods (Standard, Custom, Itoh, Quality-Guided)
2. CSI Processing: Amplitude/phase extraction, temporal smoothing, Hamming windowing
3. Feature Extraction: Doppler, PSD, amplitude, phase, correlation features
4. Motion Detection: Variance-based with adaptive thresholds

Consequences

Positive

• Pure Rust implementation (no FFI overhead)
• WASM compatible (rustfft is pure Rust)
• NumPy-like API with ndarray
• High performance with SIMD optimizations

Negative

• ndarray-linalg requires BLAS backend for advanced operations
• Learning curve for ndarray patterns

References

• ndarray documentation
• rustfft documentation