Channel Modeling for Integrated Sensing and Communications in Vehicular Environments: Conceptualization and Challenges

Integrated sensing and communication (ISAC) is a novel design concept that seeks to provide dual communication and sensing (C&S) functionalities by employing the same transmission resources. An ISAC design is particularly appealing for connected and autonomous vehicles (CAVS) applications, where the synergy of the C&S technologies is fundamental to prevent accidents and make road navigation more efficient. The engineering of ISAC systems for CAVS relies on a proper understanding and characterization of the attributes of the vehicular radio channel that influences the joint performance of the C&S subsystems. However, channel modeling for ISAC remains an underexplored research topic. This article aims to reduce the gap by providing a systematical classification of ISAC channels for vehicular applications, considering three fundamental modes of sensing. For such sensing modes, a deconstructed model of the ISAC-oriented vehicular (ISAC-V) channel is devised as a benchmark for new developments. An overview of the recent advances on ISAC channel modeling is also given along with a summary of open problems and challenges that still need to be addressed.