Estimating Timing Advance for Sub-THz Distributed Systems from Sub-10 GHz Channel State Information

Abstract

Dual-band wireless architectures transmit the control information over the sub-10 GHz while reserving sub-THz for high data rate links, offering notable capacity gains. However, a critical bottleneck in such systems is timing synchronization. Due to the narrow beams of the sub-THz radio units (RUs), when the dual-band user equipment (UE) rotates or moves, it becomes necessary to switch the transmission between the sub-THz RUs. This switching requires recalibrating the timing of uplink (UL) and downlink (DL) transmissions to prevent communication disruptions. Moreover, for sub-THz RUs, the method introduces significant overhead and latency, especially when switches are frequent. Leveraging the reliable sub-10 GHz band offers greater resilience to UE mobility, making it suitable for control signalling. Thus, in this paper, we propose a deep learning-based algorithm that infers the propagation delay from the sub-THz RUs to the UE using sub-10 GHz channel characteristics. The inferred delay is used for calculating the timing advance for UL transmissions without the need for two-way synchronization. Simulation results show that the RU switch can be made seamless at the physical layer, without incurring any synchronization-related latency.