Optimal beamforming and wave-form design for future THz communications networks

The increasing demands for high data rates in beyond (B5G) networks to support the emerging applications in these networks have spurred research on the enabling communication schemes to meet these requirements. Among these candidate schemes is Terahertz (THz) communications where the abundant bandwidth at these bands would enable achieving the 1 Tbps peak data rate, up to 10 Gbps experience data rate with good reliability for short-range applications in B5G networks. In the past, THz-band applications have been limited to sensing, imaging, and localization. This was due to the lack of compact high-power signal transmitters and high-sensitivity detectors at this band. Recent advancements in THz transceiver devices have paved the way for THz communications; however, the large path loss and sensitivity to line-of-sight (LOS) conditions at such high frequency bands require a clever design of the communication schemes at this band. This research project targets investigating the optimal multiple access, modulation, and cooperative beamforming schemes using the spectral efficiency and achievable rates as well as the energy efficiency metrics. The results obtained from this project will shed new light on the design, performance gains and trade-offs of these communication schemes in THz systems networks for full channel state information (CSI) and partial CSI depending on the adopted estimation algorithms. The tasks of this project will proceed in the following succession. In the first phase, related literature reviews have already been conducted in a previous work by the PI and his students; however, the review has to be updated to include the up-to-date work and to further focus on the optimal multiple access and cooperative/collaborative beamforming schemes (user cooperation and/or base station collaboration) to combat the high path loss and improve the energy efficiency. This will enable the development of novel contexts for such schemes in the THz band and then the analytical and/or numerical solutions of the resulting typically non- convex optimization problems using the appropriate methods. Ultimately, we aim to illustrate that, under sufficient network densification, multiple users can indeed be efficiently accommodated in the access domain of THz systems, despite the narrow THz beams and the limited communication distances. This second phase aims to study the interplay between the THz massive MIMO beamforming gains that can overcome the limitation in communication distances and the optional (yet significant) THz MIMO spatial/index modulation and multiplexing paradigms that further enhance spectral efficiency. The drawn conclusion will answer fundamental questions about the scalability and practicality of THz systems in future wireless communication standards.