Integrated THz/mmWave Transmission Method for Enhanced URLLC Communications

Ultra-Reliable and Low-Latency Communication (URLLC) is considered one of the key use cases in the current 5G and future 6G mobile communication networks. In this work, a hybrid transmission scheme is proposed to improve reliability in Terahertz (THz) bands employing adaptive diversity combining at the destination. The proposed scheme combines two links, the first link is a THz link (offering higher capacity but less reliable connectivity) as the main link, and the second link is a millimetre wave (mmWave) link (offering lower capacity but more reliable connectivity) as the backup link. The proposed scheme utilises both links dynamically exploiting the benefits of transmitting over both frequency bands by changing between the main link only and joint main/backup links based on the instantaneous quality of the channel for the main link. The received signals are combined at the destination using Selection Combining (SC) and Maximal Ratio Combining (MRC). The performance of the proposed scheme is evaluated analytically considering the Fluctuating Two-Ray (FTR) and α−μ models for the mmWave and THz links, respectively. The obtained results show that the proposed hybrid transmission scheme achieves the same reliability provided by the continuous dual-link transmission scheme, where both links (THz and mmWave links) are used continuously for transmission, thus making the proposed scheme an appropriate solution to provide URLLC applications in a resource-efficient manner.