Characterization of 300 GHz Wireless Channels for Rack-to-Rack Communications in Data Centers

This paper presents characterization of 300 GHz channel with optical lenses for wireless rack-to-rack data center communications. Measurements are conducted in line-of-sight (LoS), obstructed-LoS (OLoS), reflected-non-LoS (RNLoS), and obstructed-RNLoS (ORNLoS) scenarios, which evaluate the impact of obstructions such as cables on THz propagation as well as possibility of using existing metal objects as reflectors that guide waves for non-LoS type of links that are prevalent in data centers. Since optical lenses are needed to extend the communication range beyond 1m, we have evaluated path loss in such an environment and estimated path loss model parameters. The results indicate that optical lenses create a waveguide-like environment with PLEs of 1.54 in the LoS link and 1.36 in the RNLoS link. Multiple reflections are observed in PDPs when lenses are used to extend the distance but they decay as the distance increases. Additionally, reflector in the RNLoS link preserves multiple reflections longer than traditional LoS link and thus limit the coherence bandwidth Bc. Finally, when obstructions are present, the ORNLoS link has lower pathloss at distance beyond 130 cm and has less multipath compared to the OLoS link. If obstructions caused by cables are unavoidable, ORNLoS link performs better than OLoS link.