Truly Mobile Sub-Terahertz Communications Beyond6G via Just-in-Time IMU-Assisted Beam Management

Sub-Terahertz (sub-THz) communication is a candidate technology for beyond-sixth-generation (beyond-6G) wireless networks, promising up to Terabit-per-second data rates and microsecond-level latencies. However, the highly directional sub-THz beams required to overcome severe path loss make maintaining reliable beam alignment under mobility extremely challenging. Existing reactive in-band and out-of-band sensor-assisted beam management strategies are often insufficient to prevent outages caused by unpredictable user motion. Progress is further challenged by the absence of comprehensive evaluation platforms that jointly account for: (a) realistic user mobility, (b) real-time sensor data, and (c) accurate characteristics of sub-THz hardware. To address these challenges, we introduce: (i) Just-in-Time (JIT), a hybrid proactive and reactive beam management algorithm that fuses RF and inertial measurement unit (IMU) data to preemptively realign the link before failure, and (ii) MobileTHz, an integrated simulation and Hardware-in-the-Loop platform for mobile sub-THz systems. Benchmarked against an in-band hierarchical search and a sensor-assisted reactive algorithm, JIT significantly improves mean capacity, reduces variance, and maximizes link availability while incurring a signaling overhead of less than 0.4% of the channel capacity. Together, JIT and MobileTHz advance efficient, resilient, and truly mobile sub-THz communication systems beyond 6G.