Measurement-Based Indoor Millimeter Wave Blockage Models

Blockage is a substantial problem at millimeter wave (mmWave) frequencies, much more so than sub-6 GHz. Blockage events caused by objects such as cars and humans occur quickly and have substantial attenuation; typical attenuations in this work range from 11 to 22 dB, with a maximum of 32 dB. This problem is overcome with spatial diversity. During blockage events, mmWave transceivers can beamform towards an unblocked path. In this paper we explore this idea in depth: if the primary path is blocked, which alternate paths will be available? To answer this question, we have built a measurement system that uses 60 GHz phased arrays to rapidly obtain spatially resolved measurements of the channel. Scans are repeated every 3.2 ms, allowing us to observe blockage events that occur on the different paths in the channel. The design of this system is presented, and a description is given of three human-body blockage measurement campaigns. Paths are assigned states of blocked/unblocked, and each measurement is expressed as a time series of states which specify the status of each path. The evolution between states is described with a Markov model, and the measurement results are used to derive transition probabilities between states.