TAB-MAC: Assisted beamforming MAC protocol for Terahertz communication networks

Terahertz (THz) communication is envisioned as one of the key technologies to satisfy the increasing demand for higher-speed wireless communication networks. The very high path loss at THz frequencies and the power limitations of THz transceivers limit the communication distance in THz networks. Beamforming directional antennas are needed simultaneously in transmission and in reception to communicate over distances beyond a few meters. This results in many challenges at the link layer, which cannot be easily addressed with existing Medium Access Control (MAC) protocols. In this paper, an Assisted Beamforming MAC protocol for THz communication networks (TAB-MAC) is presented. The protocol exploits two different wireless technologies, namely, WiFi at 2.4 GHz and THz-band communication. In particular, nodes rely on the omnidirectional 2.4 GHz channel to exchange control information and coordinate their data transmissions (Phase 1), whereas the actual data transfer occurs at THz frequencies only after the nodes have aligned their beams (Phase 2). A mathematical framework is developed to analyze the performance of the TAB-MAC protocol in terms of packet delay and throughput, and theoretical upper bounds are derived as functions of total data size, data frame size, node density and data rate in THz band. Numerical results are provided to evaluate the performance of the proposed protocol under different scenarios and define the protocol design guidelines. The results show that the proposed protocol maximizes the THz channel utilization and achievable throughput. (C) 2016 Elsevier B.V. All rights reserved.