  The emergence of the fifth-generation (5G) New Radio (NR) technology has
provided unprecedented opportunities for vehicle-to-everything (V2X) networks,
enabling enhanced quality of services. However, high-mobility V2X networks
require frequent handovers and acquiring accurate channel state information
(CSI) necessitates the utilization of pilot signals, leading to increased
overhead and reduced communication throughput. To address this challenge,
integrated sensing and communications (ISAC) techniques have been employed at
the base station (gNB) within vehicle-to-infrastructure (V2I) networks, aiming
to minimize overhead and improve spectral efficiency. In this study, we propose
novel frame structures that incorporate ISAC signals for three crucial stages
in the NR-V2X system: initial access, connected mode, and beam failure and
recovery. These new frame structures employ 75% fewer pilots and reduce
reference signals by 43.24%, capitalizing on the sensing capability of ISAC
signals. Through extensive link-level simulations, we demonstrate that our
proposed approach enables faster beam establishment during initial access,
higher throughput and more precise beam tracking in connected mode with reduced
overhead, and expedited detection and recovery from beam failures. Furthermore,
the numerical results obtained from our simulations showcase enhanced spectrum
efficiency, improved communication performance and minimal overhead, validating
the effectiveness of the proposed ISAC-based techniques in NR V2I networks.
