Truly mobile sub-terahertz communications beyond 6G via just-in-time IMU-assisted beam management

Abstract Sub-Terahertz (sub-THz) communication is a candidate for beyond-sixth-generation (beyond 6G) networks, promising Terabit-per-second rates at microsecond latencies. However, the highly directional beams required to overcome severe path loss make beam alignment under mobility challenging. Existing reactive in-band and out-of-band sensor-assisted strategies often fail to prevent outages from unpredictable user motion. Progress is further limited by the absence of evaluation platforms jointly capturing realistic mobility, real-time sensor data, and sub-THz hardware. We introduce just-in-time (JIT), a hybrid proactive and reactive beam management algorithm that fuses RF and inertial measurement unit (IMU) data to realign the link before failure, and MobileTHz , an integrated simulation and hardware-in-the-loop platform for mobile sub-THz systems. Benchmarked against a hierarchical search and a reactive IMU-assisted algorithm, JIT improves mean capacity, reduces capacity variance, and increases link availability, while incurring signaling overhead below 0.4% of capacity. Together, JIT and MobileTHz advance truly mobile sub-THz communication beyond 6G.