Sliding window-based LSTM scheme for PAM-4 photonics-assisted W-band ISAC systems

In this Letter, a sliding window-based long short-term memory (LSTM) network and a correlation-based ranging scheme are proposed for a 4-level pulse amplitude modulation (PAM-4) photonics-assisted W-band integrated sensing and communication (ISAC) system. Employing the proposed method, a single PAM-4 waveform is capable of implementing both communication and sensing simultaneously. Moreover, the sliding window-based LSTM network can effectively improve receiver sensitivity. By utilizing the correlation-based ranging scheme, the centimeter-level ranging resolution can be achieved. The experimental results show that, compared with Volterra Series-based Nonlinear Equalizer (VNE), a receiver sensitivity gain of 1.2 dB is obtained at the Soft-Decision Forward Error Correction (SD-FEC) limit. In addition, the ranging resolution reachs up to 1.875 cm, and the average ranging error is 0.43 cm.