Waveform Design Based on Subcarrier Optimization for Integrated Satellite-Terrestrial Sensing and Communication

Communication signal form-based waveforms are compatible with the existing communication networks, which significantly reduce system costs and improve engineering feasibility. Orthogonal Frequency Division Multiplexing (OFDM) waveform, known for their high spectral efficiency and capability to combat inter-symbol interference, has been widely applied. However, these existing ISAC waveform design methods are primarily focused on fixed subcarrier allocation schemes, and thus the potential benefits of flexible subcarrier partitioning in waveform optimization are neglected. To address this limitation, this paper proposes an ISAC waveform design optimization framework based on the joint degrees of freedom in subcarrier partitioning and sequence symbol optimization. On one hand, communication subcarriers and radar subcarriers are allocated within the frequency band. On the other hand, the sequence symbols optimization strategy is employed for integrated sensing and communication. On this basis, a subcarrier optimizationbased waveform design method is presented with regard to satellite-terrestrial networks. This method possesses a balanced trade-off among performance, cost, and feasibility in ISAC waveform design.