Unlike the Swiss company Stratxx, which targets civil applications, this annoucement from the US research organization RTI aims at military and homeland security applications. The other difference is that they are experimenting with paint-on antennas, which provide for weight savings. Not sure if that is indeed a substantial total weight saving since other equipment might be much heavier than the antennas. But payload is critical so they certainly look at everything. The other difference is that they seem to use off-the-shelf airships for these altitudes (21km). Other partners are NASA and a company that has gathered experience with Iridium already.