Abstract: ‍ ‍With the rapid development of wireless technology， wireless devices have shown an explosive growth trend， resulting in increasingly scarce spectrum resources and continuous overlap of radar and communication bands. To avoid the mutual interference between wireless communication and radar sensing， integrated sensing and communication technology has been widely studied in the academic community， and the orthogonal time frequency space （OTFS） signal has been a research hot spot. This signal has the potential to realize the integration of wireless communication and radar sensing； however， it is particularly sensitive to fractional Doppler. Nevertheless， fractional Doppler elevates the OTFS Doppler sidelobe and causes a Doppler dispersion effect， which not only generates major interference between communication data and radar data， but also leads to the flooding of weak targets by the strong target sidelobe. This then affects the radar probability of detection and the estimation accuracy of the communication channel， and deteriorates the overall performance. Aiming at solving the problem of OTFS performance degradation caused by fractional Doppler， a design method of OTFS integrated signal based on a prototype filter is proposed. The Doppler sidelobe is adjusted by the prototype filter， to suppress the Doppler dispersion effect and reduce the communication error rate without significant loss of Doppler resolution. Aiming at solving the problem of high computational complexity of the OTFS cross-correlation matched filter channel estimation algorithm， the idea of using constant false alarm rate （CFAR） detection for channel estimation is further proposed. While reducing the computational complexity， multiple targets with the same delay and different Doppler are robustly detected， which ensures the performance of channel estimation and target detection. According to theoretical analysis and simulation experiments， the technique presented in this paper can reduce the bit error rate of communication under fractional Doppler conditions by two orders of magnitude.