Temporal dynamics of mobile blocking in millimeter wave based wearable networks

Wireless channels in millimeter wave based wearable networks are particularly susceptible to environmental blockages and dynamics when there are humans/objects in motion. Such dynamics imply, not only physical layer overheads to discover and track viable transmission paths, but also MAC overheads to keep track of neighboring interferers, perform clustering and enable proper scheduling of transmissions. We shall focus on overheads at timescale associated with the latter. This paper introduces a stochastic geometric model to study the impact of mobility on overheads in such networks. We provide a complete characterization of the temporal dynamics of strong interference channels resulting from blocking in networks comprising both fixed and mobile nodes. We show the state of a channel, Line-of-Sight(LOS)/Non-LOS(NLOS), follows an on/off renewal process and derive the associated distributions. Our model further enables us to evaluate how the overall rate of change for the set of strong LOS interferers seen by a fixed user scales with user density and proportion of mobile users. The overhead to track the interference environment may in fact be limited with user density but increases with proportion of mobile users. In a highly mobile environment, the changes in channels are frequent and the overheads for coordination become high, with distant and/or mobile users requiring more overheads. Based on our results, we suggest fixed users may coordinate with close by neighbors while mobile users are better off resorting to simpler ad hoc MACs.