Wireless real-time transmission of 101GHz terahertz signals over 19.6 km: fully solid-state prototype design and experimental validations

Abstract This study addresses the growing demand in modern military communications for high throughput, long-range transmission, with strong anti-eavesdropping capability. We design a spread spectrum-based terahertz (THz) wireless transmission system operating at 101 GHz, and conduct field trials over 10.9 km and 19.6 km. To address the key signal processing challenges, three tailored algorithms are introduced: (1) a stage-wise digital predistortion (DPD) method based on iterative learning architecture (ILA) to compensate for power amplifier (PA) nonlinearities; (2) a low-complexity energy aggregation strategy that enables robust synchronization of long spreading codes at low SNR; (3) a decision-directed least mean square (DD-LMS) algorithm to adaptively suppresses local oscillator (LO) induced phase noise. Field experiments demonstrate a stable over-the-air throughput of 2.25 Gbps over 19.6 km, while spread-spectrum processing enhances interference resilience. These results confirm that the proposed prototype offers a practical and effective solution for secure, long-distance THz communications, with strong potential for deployment in complex military scenarios.