Geometric-Sequence-Decomposition-Based Joint Range and Velocity Estimation in OFDM Radar System for UAM Applications

Urban air mobility (UAM) technologies are evolving rapidly, accompanied by a growing demand for advanced sensing and communication systems to enhance environmental awareness. The orthogonal frequency-division multiplexing (OFDM) radar-based joint radar and communication (JRC) systems have emerged as a key solution. The utilization of these systems in UAM applications allows for efficient use of limited frequency bands and eliminates the need for extra hardware installations. However, employing communication protocols, such as long-term evolution, presents a challenge due to the diminished range and velocity resolution in the OFDM radar system. Thus, a method for accurate estimation of range and velocity is necessary for OFDM radars. In this study, a geometric sequence decomposition-based accurate range and velocity estimation method is introduced. This method decomposes the received data into a superposition of geometric sequences, where each geometric sequence contains the propagation delay and Doppler shift (i.e., range and velocity of the target). Multiple simulations were conducted to validate the efficacy of our proposed method. When the signal-to-noise ratio is over 8 dB, the difference between the true and estimated range and velocity was less than the +/- 1 m or +/- 1 m/s. Furthermore, air-to-everything communications efficacy is validated based on the bit error rate analysis. According to the results, utilizing the proposed method can enhance the performance of the JRC system for the application in UAM.