Integrating Low-Complexity and Flexible Sensing Into Communication Systems

• Published in: IEEE journal on selected areas in communications Vol. 40; no. 6; pp. 1873 - 1889
• Main Authors: Wu, Kai, Zhang, J. Andrew, Huang, Xiaojing, Guo, Y. Jay
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Communication; Communications systems; Complexity; DFT-spread OFDM; Discrete Fourier transforms; Doppler effect; dual-function radar communications (DFRC); Flexibility; Fourier transforms; Integrated sensing and communications (ISAC); joint communications and sensing (JCAS); OFDM; orthogonal time-frequency space (OTFS); range-Doppler map (RDM); Receivers; Sensors; Signal to noise ratio; Time-frequency analysis
• DOI: 10.1109/JSAC.2022.3156649
• ISSN: 0733-8716

Integrating sensing into standardized communication systems can potentially benefit many consumer applications that require both radio frequency functions. However, without an effective sensing method, such integration may not achieve the expected gains of cost and energy efficiency. Existing sensing methods, which use communication payload signals, either have limited sensing performance or suffer from high complexity. In this paper, we develop a novel and flexible sensing framework which has a complexity only dominated by a Fourier transform and also provides the flexibility in adapting to different sensing needs. We propose to segment a whole block of echo signal evenly into sub-blocks; adjacent ones are allowed to overlap. We design a virtual cyclic prefix (VCP) for each sub-block that allows us to employ two common ways of removing communication data symbols and generate two types of range-Doppler maps (RDMs) for sensing. We perform a comprehensive analysis of the signal components in the RDMs, proving that their interference-plus-noise (IN) terms are approximately Gaussian distributed. The statistical properties of the distributions are derived, which leads to the analytical comparisons between the two RDMs as well as between the prior and our sensing methods. Moreover, the impact of the lengths of sub-block, VCP and overlapping signal on sensing performance is analyzed. Criteria for designing these lengths for better sensing performance are also provided. Extensive simulations validate the superiority of the proposed sensing framework over prior methods in terms of signal-to-IN ratios in RDMs, detecting performance and flexibility.