NeTS: Small: Design and Measurement of Random Reflectors to Boost Terahertz MIMO Performance

The next generation of wireless networks (cellular 6G and beyond) have the goal of providing very high data rates to support novel applications such as tele-presence and immersive reality. The terahertz (THz) frequency band, which ranges from 100 GHz to 3,000 GHz is being considered for these services as it is capable of supporting data rates in excess of terabit/sec.

However, these high frequencies are severely diminished by distance and any obstacles in their path. As a result, novel technologies are required that can enhance the propagation of these frequencies to achieve such high data rates. This proposal seeks to develop one such technology called random reflective surfaces.

When terahertz signals bounce off these reflectors, their ability to carry more information is enhanced. This work will build random reflectors and experimentally evaluate their properties. In addition, a theory of how these special reflective surfaces work will be developed.

The broad impact of this work includes furthering research in the field of terahertz communications as well as on the broader goal of enabling 6G technologies. This work will also provide internship opportunities for high-school students. These students will be exposed to the process for conducting research and will gain hands-on knowledge of this emerging field. Thus, the broader impacts on workforce development are significant.

The particular focus in this proposal is on improving the performance of terahertz MIMO (Multiple Input Multiple Output) channels in THz range. Due to the very poor propagation behavior, there is very limited multi-path possible and thus most of the connections will use LoS (Line of Sight) MIMO. A well-known problem with LoS MIMO is that the channel matrix becomes single rank in the far field, resulting in a drop in capacity since spatial multiplexing is not feasible.

This proposal presents an approach for artificially creating a rich multi-path environment using random reflective surfaces. The design of these reflectors is such that they produce multiple reflections of variable delays. This results in the reflected MIMO channel having high rank, which in turn means higher capacity.

This work will involve measurements of fabricated reflectors as well as theoretical development. The reflectors will be experimentally characterized for frequencies up to 700 GHz.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.