Design of OTFS Signals with Pulse Shaping and Window Function for OTFS-Based Radar

We propose a pulse radar system that employs a generalized window function derived from the root raised cosine (RRC), which relaxes the conventional constraint that the window values are within the range [0, 1]. The proposed window allows both negative values and values exceeding 1, enabling greater flexibility in signal design. The system transmits orthogonal time frequency space (OTFS) signals intermittently, establishing a flexible input-output relationship that captures both fractional delays and Doppler shifts. By combining the generalized RRC window with a rectangular pulse, the resulting pilot signal achieves a sharp concentration in the ambiguity function over both the delay and Doppler domains. To enhance the estimation accuracy of fractional parameters, we apply frequency-domain interpolation based on the autocorrelation of the RRC window, which outperforms conventional linear interpolation by preserving the signal structure more effectively.

2D Sinc Interpolation-Based Fractional Delay and Doppler Estimation Using Time and Frequency Shifted Gaussian Pulses

An accurate delay and Doppler estimation method for a radar system using time and frequency-shifted pulses with pseudo-random numbers is proposed. The ambiguity function of the transmitted signal has a strong peak at the origin and is close to zero if delay and Doppler are more than the inverses of the bandwidth and time-width. A two-dimensional (2D) sinc function gives a good approximation of the ambiguity function around the origin, by which fractional delay and Doppler are accurately estimated.