Invited Article: Channel performance for indoor and outdoor terahertz wireless links

Abstract

One of the most exciting future applications of terahertz technology is in the area of wireless communications. As 5G systems incorporating a standard for millimeter-wave wireless links approach commercial roll-out, it is becoming clear that even this new infrastructure will not be sufficient to keep pace with the rapidly increasing global demand for bandwidth. One favorable solution that is attracting increasing attention for subsequent generations of wireless technology is to use higher frequencies, above 100 GHz. The implementation of such links will require significant advances in hardware, algorithms, and architecture. Although numerous research groups are exploring aspects of this challenging problem, many basic questions remain unaddressed. Here, we present an experimental effort to characterize THz wireless links in both indoor and outdoor environments. We report measurements at 100, 200, 300, and 400 GHz, using a link with a data rate of 1 Gbit/s. We demonstrate both line-of-sight and non-line-of-sight (specular reflection) links off of interior building walls. This work represents a first step to establish the feasibility of using THz carrier waves for data transmission in diverse situations and environments.

Indoor Wireless Channel Properties at Millimeter Wave and Sub-Terahertz Frequencies

“…Using the ǫ r = 6.4 of drywall at 140 GHz from Section II-B, a reflection loss of 7.25 dB is predicted (∼18.8% of the power is reflected), which is comparable to the reflected power (∼8 dB) measured in [18] at 100 GHz. In addition, as seen in Section III, 14.3% of the incident power is transmitted through drywall at 142 GHz (8.46 dB partition loss was measured).…”

“…Signals with larger incident angles were shown to experience less loss due to the combined effects of reflection, absorption, and scattering. The scattering loss of bare cinderblock walls at 400 GHz was shown to be negligible [18].…”

“…Work in [18] showed that absorption imposed a ∼8dB penalty to the reflection power (nearly 16% of the signal power imping on the reflection surface is reflected and about 84% of the power is absorbed) from an indoor painted cinderblock wall at 100 GHz and the effect of scattering from the painted cinderblock wall is significantly smaller than the effect of absorption. It is worth noting that the absorption mentioned in [18] includes the power penetrating through the wall and the power absorbed by the wall.…”

“…Maximum transmission rates of several tens of Gbps for line of sight (LOS) and several Gbps for non-LOS (NLOS) paths were shown to be achievable at 300-350 GHz [17]. Measurements at 100, 200, 300, and 400 GHz using a 1 GHz RF bandwidth channel sounder showed that both indoor LOS and NLOS links (specular reflection from interior building walls) could provide a data rate of 1 Gbps [18]. Signals with larger incident angles were shown to experience less loss due to the combined effects of reflection, absorption, and scattering.…”

THz Communication Technology in India Present and Future

“…2, inevitably lead us to formulate the strategic viability plan of THz application in communication. It can be seen, that, contrary to traditional approach of longrange front-end communication channel THz range, and especially the higher frequency range with the capability of supporting high data rate, is suitable for short-range to very-short-range communication 17 . In these short-links, the 'atmospheric attenuation' issue of THz range becomes negligible and the advantages of 'material transparency' and 'high metal reflectivity' would enable us to configure communication channels based on the use of selected THz frequency windows coupled with strategic placements of active and passive material components (like, waveguides, filters and optical amplifiers etc.)…”