OTFS Channel Estimation with Frequency Domain Spectral Shaping and Extension

The widely used embedded impulse pilot for channel estimation of orthogonal time frequency space modulation (OTFS) needs ample guard space between data and pilot symbols. This paper proposes a frequency domain pulse shaping with spectral extension to reduce the effective channel length, reduce the guard space, and improve the bandwidth efficiency of OTFS. We propose a two-stage channel estimation method exploring the delay-time and time-frequency domain channel properties. The proposed method extracts the impulse response in the delay-time domain and transforms it into the delay-Doppler domain. Pulse shaping with spectral extension reduces pilot data interactions and relaxes the strong pilot power required for channel estimation in traditional impulse-based methods. By reducing pilot power and applying spectral extension with shaping, the bit error rate improves by 2–8 dB across different modulation orders, along with a 3–4 dB reduction in PAPR.