arXiv:2606.19724v2 Announce Type: replace Abstract: Nonzero sidelobes in matched-filter pulse-compression distributed acoustic sensing (DAS) cause deterministic inter-range-bin leakage, termed spatial inter-symbol interference (ISI), and may produce false Rayleigh-backscatter responses. We propose a data-bearing cyclic-prefix orthogonal frequency-division multiplexing (CP-OFDM) DAS system for phase-sensitive optical time-domain reflectometry (phi-OTDR), using the same waveform for probing and forward communication. To our knowledge, this is the first formulation of distributed Rayleigh backscattering as a finite-memory sensing multipath channel. We rigorously prove that, when the useful OFDM and CP lengths cover the channel memory, the receiver reconstructs range-bin coefficients without deterministic waveform-induced spatial ISI. CP removal, one-tap frequency-domain equalization, and inverse discrete Fourier transform provide the reconstruction for subsequent gauge-differential phase demodulation. In a simulated 5.2-km link with ten simultaneous strong and weak events spaced 5.31-5.83 m within groups, CP-OFDM suppresses off-event spatial-ISI leakage. Phase-trace mean-square error improves by up to 29.55 dB over matched-filter pulse compression. A heterodyne coherent experiment over 5.2 km at a 111.984-MHz occupied bandwidth recovers 500-Hz vibrations near 80 m under 1- and 5-V piezoelectric transducer drives. Under identical probing conditions, CP-OFDM improves the vibration-to-background ratio by approximately 3.2 and 6.2 dB, respectively, over matched-filter linear frequency-modulated pulse compression while preserving local waveforms. The same probe recovers an image with zero measured bit-error rate and a median error vector magnitude of -23.14 dB. These results validate spatial-ISI-free DAS reconstruction and provide an initial demonstration of shared-waveform optical-fiber integrated sensing and communication (ISAC).