Dual-Radio-Assisted (DRA) MAC Protocols for Distributed Terahertz Networks

Terahertz (THz) communication is envisioned as one of the key technologies to satisfy the high data rate demand of intelligent 6G networks. However, directional transmissions, as well as the peculiarities of the THz band, pose challenges on medium access control (MAC) design. In this paper, a dual-radio-assisted MAC protocol supporting concurrent transmission is proposed, in which 2.4/5 GHz omnidirectional radio is utilized for control signaling, while THz beamforming is adopted for data transmissions. The request-to-send (RTS-GHz)/test-to-transmit (TTT-THz) handshake is adopted for initial link establishment. Furthermore, the network table is constructed at each node recording receiver-oriented network allocation vector (RNAV) value, angle-of-departure (AoD) of DATA, and angle-of-arrival (AoA) of RTS-GHz. The RNAV record enables concurrent transmission without collision. The record of the first two dominant AoA paths alleviates the LoS blockage problem. The AoD record further decreases the link association delay by replacing RTS-THz with RTS-GHz. Network performances on the protocol are analytically and numerically investigated. Results indicate that the proposed DRA-MAC protocol with AoD memory can achieve 88.2%, 51.6%, and 50% improvement in average link delay, throughput, and LoS blockage alleviation respectively, compared with existing THz MAC protocols.