Intra-Gauge Rotated Vector Sum (IG-RVS) for Rayleigh Fading Mitigation in Coherent {\phi}-OTDR Systems

We propose Intra-Gauge Rotated Vector Sum (IG-RVS), a DSP-based fading mitigation method for coherent ${\varphi}$-OTDR. IG-RVS exploits spatial diversity within the gauge length by phase-aligning and coherently summing neighboring bins, thereby suppressing Rayleigh fading while preserving spatial resolution.