  Rampant mobile traffic increase in modern cellular networks is mostly caused
by large-sized multimedia contents. Recent advancements in smart devices as
well as radio access technologies promote the consumption of bulky content,
even for people in moving vehicles, referred to as vehicular heavy users. In
this article the emergence of vehicular heavy user traffic is observed by field
experiments conducted in 2012 and 2015 in Seoul, Korea. The experiments reveal
that such traffic is becoming dominant, captured by the 8.62 times increase in
vehicular heavy user traffic while the total traffic increased 3.04 times. To
resolve this so-called vehicular heavy user problem (VHP), we propose a cell
association algorithm that exploits user demand diversity for different
velocities. This user traffic pattern is discovered first by our field trials,
which is convex-shaped over velocity, i.e. walking user traffic is less than
stationary or vehicular user traffic. As the VHP becomes severe, numerical
evaluation verifies the proposed user convexity aware association outperforms a
well-known load balancing association in practice, cell range expansion (CRE).
In addition to the cell association, several complementary techniques are
suggested in line with the technical trend toward 5G.
