Impact of Modulation Schemes on Joint Estimation of Range and Velocity for UAV-to-Ground Scenarios

The emergence of new application scenarios has enabled integrated sensing and communication (ISAC) as one of the potential technologies of 6-th generation mobile communication (6G). To meet both communication efficiency and sensing efficiency, a satisfactory ISAC waveform is essential. In this paper, we primarily investigate the impact of different modulation schemes on sensing performance for UAV-to-ground scenarios. Firstly, we analyze the sensing performance differences of modulation schemes in the sensing algorithm based on orthogonal frequency division multiplexing (OFDM) systems. Secondly, we examine the periodic auto-correlation functions (PACFs) with different modulation schemes and modulation orders. We observe that the waveforms modulated by phase shift keying (PSK) exhibit the lower sidelobes compared to waveforms modulated by quadrature amplitude modulation (QAM). Finally, we simulate the probability of detection (Pd) with different modulation schemes for UAV-to-ground scenarios. Numerical results demonstrate that the modulated waveform with constant modulus exhibit superior sensing performance. For the modulated waveform with non-constant modulus, the higher modulation orders result in the poorer sensing performance. This inspires us to change the sensing performance by designing the power spectrum of the modulated waveform with non-constant modulus. This work is helpful for the waveform design and performance analysis of ISAC.