Experimental Demonstrations of High-Capacity THz-Wireless Transmission Systems for Beyond 5G

Using the concept of a "THz-wireless fiber extender," we can combine the flexibility of wireless networks with the high capacity of fiber optic communication. The availability of a large, contiguous bandwidth in the frequency band around 300 GHz creates the opportunity to seamlessly interconnect coherent THz-wireless and fiber optic transceiver frontends using a transparent, analog baseband interface. In this article, we discuss this concept in more detail and report on the recent demonstration of a real-time, short-range THz-wireless fiber extender with 100 Gb/s net capacity. This combined fiber optic/THz-wireless transmission system is operated by a high-speed fiber optic real-time modem, which is capable of compensating the channel impairments of both the optical and THz-wireless links. In addition, we discuss the potential of THz-wireless links to achieve long-range transmission distances by reporting on the operation of a 500-m-long line-of-sight THz-wireless outdoor link in Berlin, Germany. We analyze the effect of weather conditions on the transmission performance and determine the maximum physical layer net data rate of the system by means of various modulation formats and symbol rates. Finally, we summarize all of our recent high-capacity experiments using THz-wireless transmission, including a field trial with a 1-km-long link, and compare our results to theoretical limits and achieved data rates in the laboratory.