  The millimeter wave (mmWave) bands and other high frequencies above 6~GHz
have emerged as a central component of Fifth-Generation (5G) cellular standards
to deliver high data rates and ultra-low latency. A key challenge in these
bands is blockage from obstacles, including the human body. In addition to the
reduced coverage, blockage can result in highly intermittent links where the
signal quality varies significantly with motion of obstacles in the
environment. The blockages have widespread consequences throughout the protocol
stack including beam tracking, link adaptation, cell selection, handover and
congestion control. Accurately modeling these blockage dynamics is therefore
critical for the development and evaluation of potential mmWave systems. In
this work, we present a novel spatial dynamic channel sounding system based on
phased array transmitters and receivers operating at 60 GHz. Importantly, the
sounder can measure multiple directions rapidly at high speed to provide
detailed spatial dynamic measurements of complex scenarios. The system is
demonstrated in an indoor home-entertainment type setting with multiple moving
blockers. Preliminary results are presented on analyzing this data with a
discussion of the open issues towards developing statistical dynamic models.
