Millimeter-Wave and THz Integrated Sensing and Communication Systems: Architecture and Applications in Smart Cities and V2X

Abstract

Multi-band vehicle-to-everything integrated sensing and communication (ISAC) creates a decision conflict because the band that maximizes a direct communication link need not provide a reliable target echo. This paper proposes DSA-HISAC, a risk-aware heuristic for assigning a roadside unit and either 28 GHz or 142 GHz using conservative communication- and sensing-SNR estimates, predicted blockage, service risk, anticipated shared bandwidth, and frequency-band switching hysteresis. The method is evaluated at a four-way urban intersection with SUMO-generated motorized traffic and stochastic pedestrian crossings. The 28 GHz propagation model is 3GPP urban-microcell inspired, whereas 142 GHz uses measurement-derived outdoor exponents; both are simulation abstractions rather than claims of standards compliance. The revised campaign contains 120 matched runs across four traffic-demand levels and compares 13 methods, including joint-feasible, robust, and load-aware maximum-rate baselines. The primary equal-denominator metric assigns zero goodput when no link is selected or when either mandatory communication or sensing feasibility fails. DSA-HISAC attains a joint-feasibility fraction of 0.9467 and mean unconditional goodput of 2151.8 Mbit/s. Relative to load-aware robust max-rate, its changes are +1.19 percentage points in joint feasibility and +657.7 Mbit/s in unconditional goodput; the violation fraction among attempted selections changes from 1.283% to 0.022%. Compared with communication-only maximum-rate selection, DSA-HISAC changes joint feasibility by +12.94 percentage points and goodput by +899.5 Mbit/s. Risk-adaptive sensing reduces scheduled scan demand by 20.4% relative to fixed 10 Hz sensing, while information age is reset only after a valid sensing update. The results establish a controllable feasibility-goodput-overhead trade-off. They do not demonstrate end-to-end latency, packet reliability, beam tracking, standards compliance, or field safety.