A Spectrum Efficient Waveform Integrating OFDM and FMCW for Joint Communications and Sensing

Abstract

The main challenge of joint communications and sensing is how to integrate the two functions efficiently. Simple orthogonal coexistence cannot acquire integration gain, while using orthogonal frequency-division multiplexing (OFDM) to sense requires complex and costly in-band full-duplex. To solve these problems, this paper proposes a novel waveform named flexible sensing implanted OFDM (FSI-OFDM), where sensing resources can be flexibly allocated. FSI-OFDM is compatible with existing OFDM schemes, and the mapping principle is shown and proved. FSI-OFDM gains both super sensing range (SSR) and simple self-interference (SI) cancellation. Via random Doppler sampling, a sensing range and resolution as good as the sensing-only scheme can be achieved with much less sensing resources. FSI-OFDM can also utilize the cyclic prefix to gain super distance range. Furthermore, a receiving algorithm with simple analog SI cancellation is proposed. The simulation results show that FSI-OFDM gains a 4-time Doppler range or a 2-time distance range, compared with existing orthogonal coexistence schemes.