AFDM-enabled, photonics-aided fiber-wireless fronthaul system for integrated sensing and communication.

Integrated sensing and communication (ISAC) has been widely recognized as a cornerstone of sixth-generation (6G) networks. The prevalence of doubly dispersive channels (DSCs) in high-mobility and high-frequency scenarios has emerged as a critical bottleneck for 6G networks. Affine frequency division multiplexing (AFDM), capable of attaining full diversity gain even in DSC environments, has become a compelling candidate for next-generation ISAC waveforms. In this Letter, we demonstrate a photonics-aided fiber-wireless fronthaul system employing AFDM, which enables absolute range sensing. To our knowledge, this is the first demonstration of integrating AFDM with absolute distance sensing in a fiber-wireless ISAC system. Our experimental results demonstrate the communication and sensing capabilities of the AFDM waveform using 16-ary quadrature amplitude modulation (QAM) symbols with a net data rate of 6.63 Gbit/s and a ranging resolution of 7.5 cm. Under identical experimental conditions, AFDM achieves a bit-error-rate (BER) performance similar to that of conventional OFDM with a lower overhead. The sensing results demonstrate that AFDM significantly outperforms OFDM in both single-target and multi-target sensing scenarios. AFDM achieves accurate target localization with sharp peaks and low sidelobes, while OFDM suffers from severe false peaks and position deviations due to carrier frequency offset.