We describe a measurement campaign conducted in a data center, a unique environment in which transceivers are positioned above the server racks. A total of 80 channel acquisitions, including small-scale measurements, were recorded using our 3D double-directional 60-GHz channel sounder with 0.5-ns delay resolution and 2° average angle error. For each acquisition, the channel multipath components were extracted in the delay-angle space and subsequently reduced to the parameters of the Quasi-Deterministic channel model: a stochastic map-based model that represents the scattering of incident waves off ambient reflectors as specular components, each surrounded by a cluster of diffuse components. The weaker diffuse components interfere with the stronger specular component, giving rise to small-scale fading. Only with super-resolution capabilities, such as that of our system, were we able to show how densely the diffuse components were packed, with 1/ns to 2/ns arrival rates and cluster angular spreads between 3° and 4°. Most importantly, we measured the diffuse power to be as high as 26% of the total cluster power, demonstrating that small-scale fading at mmWave frequencies can be significant.
IEEE Antennas and Wireless Propagation Letters
mmWave, millimeter-wave, wireless, server room