Orthogonal Chirp Division Multiplexing Waveform Design for 6G mmWave UAV Integrated Sensing and Communication

With the anticipation of sixth-generation (6G) networks escalating, the integrated sensing and communication (ISAC) and millimeter-wave (mmWave) unmanned aerial vehicle (UAV) communications emerge as the key focus areas. This paper presents an innovative approach to ISAC waveform design tailored for mmWave UAV communications. The orthogonal chirp division multiplexing (OCDM), characterized by a brunch of orthogonal chirp signals, is firstly introduced in UAV scenarios to offer dual sensing and communication functionalities.We propose an holistic waveform design which incorporates OCDM with the state-of-the-art mmWave frequency-modulated continuous wave (FMCW) radar. Specifically, one subcarrier in OCDM is chosen as the dedicated sensing signal to facilitate the FMCW processing at the UAV receiver, while the rest of OCDM subcarriers can be used to enhance communication data rate. Such OCDM-FMCW scheme significantly reduces the required hardware complexity, particularly in analog-to-digital converter, which provides an energy-efficient ISAC solution for the resource-constraint UAVs. Simulation results demonstrate the effectiveness and superiority of the proposed scheme. It can surpass traditional methods like OFDM and OTFS, by trading off the sensing performance, communication performance, and hardware complexity.