Intermittency Versus Path Loss in RIS-aided THz Communication: A Data Significance Approach

The transition to Terahertz (THz) frequencies, providing an ultra-wide bandwidth, is a key driver for future wireless communication networks. However, the specific properties of the THz channel, such as severe path loss and vulnerability to blockage, pose a significant challenge in balancing data rate and reliability. This work considers reconfigurable intelligent surface (RIS)-aided THz communication, where the effective exploitation of a strong, but intermittent line-of-sight (LoS) path versus a reliable, yet weaker RIS-path is studied. We introduce a mixed-criticality superposition coding scheme that addresses this trade-off from a data significance perspective. The results show that the proposed scheme enables reliable transmission for a portion of highly critical data without significantly impacting the overall achievable sum rate and queuing delay. Additionally, we gain insights into how the LoS blockage probability and the channel gain of the RIS-link influence the rate performance of our scheme.