Abstract
Future networks are envisioned to create digital twin representations of the physical world, motivated by the integrated sensing and communication (ISAC). To meet the needs, millimetre wave (mmWave) and terahertz (THz) signals shine with outstanding performance in high-speed transmission and high-accuracy perception, but requiring narrow beamwidth to compensate for high path-loss. It in turn causes severe beam misalignment that induces link failures, leaving reliable inter-cell handovers and intra-cell beam switches crucial challenges for THz/mmWave networks. Exploiting the Synchronization Signal Block (SSB) specified for beam management, we propose a system-level beam alignment scheme utilizing SSB-based sensing to assist beam switches. To fully utilize limited sensing resource, we provide a closed-form optimal SSB time-frequency pattern design that complies with current configuration. Results show that proposed scheme reduces up to 70% beam misalignment probability in highway and urban cases. Thus, guaranteeing the same beam alignment quality, sensing-aided networks can use narrower beams to enlarge network coverage. Also, the optimal resource allocation for SSB pattern design is stable against changing node density and mobility.