  The battlefield of the future will be densely populated by a variety of
entities ("things") -- some intelligent and some only marginally so --
performing a broad range of tasks: sensing, communicating, acting, and
collaborating with each other and human warfighters. We call this the Internet
of Battle Things, IoBT. In some ways, IoBT is already becoming a reality, but
20-30 years from now it is likely to become a dominant presence in warfare. To
become a reality, however, this bold vision will have to overcome a number of
major challenges. As one example of such a challenge, the communications among
things will have to be flexible and adaptive to rapidly changing situations and
military missions. In this paper, we explore this and several other major
challenges of IoBT, and outline key research directions and approaches towards
solving these challenges.
