  Vehicle-to-everything (V2X) communication is expected to support many
promising applications in next-generation wireless networks. The recent
development of integrated sensing and communications (ISAC) technology offers
new opportunities to meet the stringent sensing and communication (S&C)
requirements in V2X networks. However, considering the relatively small radar
cross section (RCS) of the vehicles and the limited transmit power of the road
site units (RSUs), the power of echoes may be too weak to achieve effective
target detection and tracking. To handle this issue, we propose a novel
sensing-assisted communication scheme by employing an intelligent Omni-surface
(IOS) on the surface of the vehicle. First, a two-phase ISAC protocol,
including the S&C phase and the communication-only phase, was presented to
maximize the throughput by jointly optimizing the IOS phase shifts and the
sensing duration. Then, we derive a closed-form expression of the achievable
rate which achieves a good approximation. Furthermore, a sufficient and
necessary condition for the existence of the S&C phase is derived to provide
useful insights for practical system design. Simulation results demonstrate the
effectiveness of the proposed sensing-assisted communication scheme in
achieving high throughput with low transmit power requirements.
